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Background: Limited data exist to guide oxygen administration during one-lung ventilation for thoracic surgery. We hypothesised that high intraoperative inspired oxygen fraction during lung resection surgery requiring one-lung ventilation is independently associated with postoperative pulmonary complications (PPCs)., Methods: We performed this retrospective multicentre study using two integrated perioperative databases (Multicenter Perioperative Outcomes Group and Society of Thoracic Surgeons General Thoracic Surgery Database) to study adult thoracic surgical procedures using one-lung ventilation. The primary outcome was a composite of PPCs (atelectasis, acute respiratory distress syndrome, pneumonia, respiratory failure, reintubation, and prolonged ventilation >48 h). The exposure of interest was high inspired oxygen fraction (FiO 2 ), defined by area under the curve of a FiO 2 threshold > 80%. Univariate analysis and logistic regression modelling assessed the association between intraoperative FiO 2 and PPCs., Results: Across four US medical centres, 141/2733 (5.2%) procedures conducted in 2716 patients (55% female; mean age 66 yr) resulted in PPCs. FiO 2 was univariately associated with PPCs (adjusted OR [aOR]: 1.17, 95% confidence interval [CI]: 1.04-1.33, P=0.012). Logistic regression modelling showed that duration of one-lung ventilation (aOR: 1.20, 95% CI: 1.03-1.41, P=0.022), but not the time-weighted average FiO 2 (aOR: 1.01, 95% CI: 1.00-1.02, P=0.165), was associated with PPCs., Conclusions: Our results do not support limiting the inspired oxygen fraction for the purpose of reducing postoperative pulmonary complications in thoracic surgery involving one-lung ventilation., (Copyright © 2024 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.)

The operating room is a unique environment where surgery exposes patients to non-physiological changes that can compromise lung mechanics. Therefore, raising clinicians' awareness of the potential risk of ventilator-induced lung injury (VILI) is mandatory. Driving pressure is a useful tool for reducing lung complications in patients with acute respiratory distress syndrome and those undergoing elective surgery. Driving pressure has been most extensively studied in the context of single-lung ventilation during thoracic surgery. However, the awareness of association of VILI risk and patient positioning (prone, beach-chair, park-bench) and type of surgery must be raised., Competing Interests: Conflict-of-interest statement: The authors declare that they have no conflict of interest., (©The Author(s) 2024. Published by Baishideng Publishing Group Inc. All rights reserved.)

Mean airway pressure (MAP) is the mean pressure generated in the airway during a single breath (inspiration + expiration), and is displayed on most anaesthesia and intensive care ventilators. This parameter, however, is not usually monitored during mechanical ventilation because it is poorly understood and usually only used in research. One of the main determinants of MAP is PEEP. This is because in respiratory cycles with an I:E ratio of 1:2, expiration is twice as long as inspiration. Although MAP can be used as a surrogate for mean alveolar pressure, these parameters differ considerably in some situations. Recently, MAP has been shown to be a useful prognostic factor for respiratory morbidity and mortality in mechanically ventilated patients of various ages. Low MAP has been associated with a lower incidence of 90-day mortality, shorter ICU stay, and shorter mechanical ventilation time. MAP also affects haemodynamics: there is evidence of a causal relationship between high MAP and low perfusion index, both of which are associated with poor prognosis in mechanically ventilated patients. Elevated MAP values have also been associated with high central venous pressure and lactate, which are indicative of ventilator-associated right ventricular failure and tissue hypoperfusion, respectively. MAP, therefore, is an important parameter to measure in clinical practice. The aim of this review has been to identify the determinants of MAP, the pros and cons of using MAP instead of traditional protective ventilation parameters, and the evidence that supports the use of MAP in clinical practice., (Copyright © 2024 Sociedad Española de Anestesiología, Reanimación y Terapéutica del Dolor. Publicado por Elsevier España, S.L.U. All rights reserved.)

Background: The successful implementation of assisted ventilation depends on matching the patient's effort with the ventilator support. Pressure muscle index (PMI), an airway pressure based measurement, has been used as noninvasive monitoring to assess the patient's inspiratory effort. The authors aimed to evaluate the feasibility of pressure support adjustment according to the PMI target and the diagnostic performance of PMI to predict the contribution of the patient's effort during ventilator support., Methods: In this prospective physiological study, 22 adult patients undergoing pressure support ventilation were enrolled. After an end-inspiratory airway occlusion, airway pressure reached a plateau, and the magnitude of change in plateau from peak airway pressure was defined as PMI. Pressure support was adjusted to obtain the PMI which was closest to -1, 0, +1, +2, and + 3 cm H 2 O. Each pressure support level was maintained for 20 min. Esophageal pressure was monitored. Pressure-time products of respiratory muscle and ventilator insufflation were measured, and the fraction of pressure generated by the patient was calculated to represent the contribution of the patient's inspiratory effort., Results: A total of 105 datasets were collected at different PMI-targeted pressure support levels. The differences in PMI between the target and the obtained value were all within ±1 cm H 2 O. As targeted PMI increased, pressure support settings decreased significantly from a median (interquartile range) of 11 (10-12) to 5 (4-6) cm H 2 O ( p  < 0.001), which resulted in a significant increase in pressure-time products of respiratory muscle [from 2.9 (2.1-5.0) to 6.8 (5.3-8.1) cm H 2 O•s] and the fraction of pressure generated by the patient [from 25% (19-31%) to 72% (62-87%)] ( p  < 0.001). The area under receiver operating characteristic curves for PMI to predict 30 and 70% contribution of patient's effort were 0.93 and 0.95, respectively. High sensitivity (all 1.00), specificity (0.86 and 0.78), and negative predictive value (all 1.00), but low positive predictive value (0.61 and 0.43) were obtained to predict either high or low contribution of patient's effort., Conclusion: Our results preliminarily suggested the feasibility of pressure support adjustment according to the PMI target from the ventilator screen. PMI could reliably predict the high and low contribution of a patient's effort during assisted ventilation. Clinical trial registration: ClinicalTrials.gov, identifier NCT05970393., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Gao, Zhou, Yang, Xu, Zhou, Zhang and Miao.)

Background: Lung- and diaphragm-protective (LDP) ventilation may prevent diaphragm atrophy and patient self-inflicted lung injury in acute respiratory failure, but feasibility is uncertain. The objectives of this study were to estimate the proportion of patients achieving LDP targets in different modes of ventilation, and to identify predictors of need for extracorporeal carbon dioxide removal (ECCO 2 R) to achieve LDP targets., Methods: An in silico clinical trial was conducted using a previously published mathematical model of patient-ventilator interaction in a simulated patient population (n = 5000) with clinically relevant physiological characteristics. Ventilation and sedation were titrated according to a pre-defined algorithm in pressure support ventilation (PSV) and proportional assist ventilation (PAV+) modes, with or without adjunctive ECCO 2 R, and using ECCO 2 R alone (without ventilation or sedation). Random forest modelling was employed to identify patient-level factors associated with achieving targets., Results: After titration, the proportion of patients achieving targets was lower in PAV+ vs. PSV (37% vs. 43%, odds ratio 0.78, 95% CI 0.73-0.85). Adjunctive ECCO 2 R substantially increased the probability of achieving targets in both PSV and PAV+ (85% vs. 84%). ECCO 2 R alone without ventilation or sedation achieved LDP targets in 9%. The main determinants of success without ECCO 2 R were lung compliance, ventilatory ratio, and strong ion difference. In silico trial results corresponded closely with the results obtained in a clinical trial of the LDP titration algorithm (n = 30)., Conclusions: In this in silico trial, many patients required ECCO 2 R in combination with mechanical ventilation and sedation to achieve LDP targets. ECCO 2 R increased the probability of achieving LDP targets in patients with intermediate degrees of derangement in elastance and ventilatory ratio., (© 2024. The Author(s).)

Background: Airway opening pressure (AOP) detection and measurement are essential for assessing respiratory mechanics and adapting ventilation. We propose a novel approach for AOP assessment during volume assist control ventilation at a usual constant-flow rate of 60 L/min., Objectives: To validate the conductive pressure (P cond ) method, which compare the P cond -defined on the airway pressure waveform as the difference between the airway pressure level at which an abrupt change in slope occurs at the beginning of insufflation and PEEP-to resistive pressure for AOP detection and measurement, and to compare its respiratory and hemodynamic tolerance to the standard low-flow insufflation method., Methods: The proof-of-concept of the P cond method was assessed on mechanical (lung simulator) and physiological (cadavers) bench models. Its diagnostic performance was evaluated in 213 patients, using the standard low-flow insufflation method as a reference. In 45 patients, the respiratory and hemodynamic tolerance of the P cond method was compared with the standard low-flow method., Measurements and Main Results: Bench assessments validated the P cond method proof-of-concept. Sensitivity and specificity of the P cond method for AOP detection were 93% and 91%, respectively. AOP obtained by P cond and standard low-flow methods strongly correlated (r = 0.84, p < 0.001). Changes in SpO 2 were significantly lower during P cond than during standard method (p < 0.001)., Conclusion: Determination of P cond during constant-flow assist control ventilation may permit to easily and safely detect and measure AOP., (© 2023. The Author(s).)

Objective: To evaluate the impact of the novel P/FP E index to classify ARDS severity on mortality of patients with ARDS., Design: A retrospective cohort study., Setting: Twelve-bed medical and surgical intensive care unit from January 2018 to December 2020., Patients: A total of 217 ARDS patients managed with invasive mechanical ventilation >48h., Interventions: None., Variables: ARDS severity on day 1 and day 3 was measured based on PaO 2 /FiO 2 ratio and P/FP E index [PaO 2 /(FiO 2 ×PEEP)]. Primary outcome was the hospital mortality., Results: Hospital mortality rate was 59.9%. Relative to PaO 2 /FiO 2 ratio, 31.8% of patients on day 1 and 77.0% on day 3 were reclassified into a different category of ARDS severity by P/FP E index. The level of PEEP was lower by P/FP E index-based ARDS severity classification than by using PaO 2 /FiO 2 ratio. The performance for predicting mortality of P/FP E index was superior to PaO 2 /FiO 2 ratio in term of AROC (day 1: 0.72 vs. 0.62; day 3: 0.87 vs. 0.68) and CORR (day 1: 0.370 vs. 0.213; day 3: 0.634 vs. 0.301). P/FP E index improved prediction of risk of death compared to PaO 2 /FiO 2 ratio as showed by the qNRI (day 1: 72.0%, p<0.0001; day 3: 132.4%, p<0.0001) and IDI (day 1: 0.09, p<0.0001; day 3: 0.31, p<0.0001)., Conclusions: Assessment of ARDS severity based on P/FP E index seems better than PaO 2 /FiO 2 ratio for predicting mortality. The value of P/FP E index for clinical decision-making requires confirmation by randomized controlled trials., (Copyright © 2022 Elsevier España, S.L.U. and SEMICYUC. All rights reserved.)

Respiratory failure occurs with some frequency in seriously burned patients, driven by a combination of inflammatory and infection factors. Inhalation injury contributes to respiratory failure in some burn patients via direct mucosal injury and indirect inflammation. In burn patients, respiratory failure leading to acute respiratory distress syndrome, with or without inhalation injury, is effectively managed using principles evolved for non-burn critically ill patients., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Mechanical ventilation is an essential component in the treatment of patients with acute respiratory distress syndrome. Prompt adaptation of the settings of a ventilator to the variable needs of patients is essential to ensure personalised and protective ventilation. Still, it is challenging and time-consuming for the therapist at the bedside. In addition, general implementation barriers hinder the timely incorporation of new evidence from clinical studies into routine clinical practice., Results: We present a system combing clinical evidence and expert knowledge within a physiological closed-loop control structure for mechanical ventilation. The system includes multiple controllers to support adequate gas exchange while adhering to multiple evidence-based components of lung protective ventilation. We performed a pilot study on three animals with an induced ARDS. The system achieved a time-in-target of over 75 % for all targets and avoided any critical phases of low oxygen saturation, despite provoked disturbances such as disconnections from the ventilator and positional changes of the subject., Conclusions: The presented system can provide personalised and lung-protective ventilation and reduce clinician workload in clinical practice., (© 2023. The Author(s).)

Background: A protective or ultra-protective tidal volume strategy is widely applied to patients with acute respiratory distress syndrome (ARDS). The use of very low tidal volume has the potential to further redece ventilation-induced lung injury (VILI) comparde with a "normal" lung protective management. Plus, cardiogenic pulmonary edema (CPE) caused by hydrostatic mechanisms in patients with cardiogenic shock has similar respiratory mechanics to those found in patients with ARDS. And no consensus exists on mechanical ventilation parameter settings in patients with VA-ECMO. The study aimed to investigate the impact of an ultra-protective tidal volume strategy on the 28-day ventilator-free day (VFD) number in VA-ECMO-supported patients with refractory cardiogenic shock, including cardiac arrest., Methods: The Ultra-ECMO trial is a randomized controlled, open-label, single-center prospective superiority trial. At the onset of ECMO initiation, we will divide patients randomly into an intervention group and a control group in a 1:1 ratio. The control group will adopt protective ventilation settings [initial tidal volume: 6 ml/kg of predicted body weight (PBW)] for ventilation, and the intervention group will adopt ultra-protective ventilation settings (initial tidal volume: 4 ml/kg of PBW) for ventilation. The procedure is expected to last 72 h, after which the ventilator settings will be at the intensivists' discretion. The primary outcome is the VFD number at 28 days after inclusion. The secondary outcomes will include respiratory mechanics; analgesic/sedation dosage; lung ultrasound score; interleukin-6, interleukin-8, and monocyte chemotactic protein-1 levels in broncho-alveolar lavage fluid at the moment of enrollment (T0), 24, 48, and 72 h (T1, T2, and T3, respectively) after ECMO initiation; total time (in days) required for ECMO weaning; length of stay in the intensive care unit; total cost of hospitalization; amounts of resuscitative fluids; and in-hospital mortality., Discussion: VA-ECMO-treated patients without ARDS possess abnormal lung function. CPE, thoracic compliance reduction, and poor pulmonary blood perfusion are frequently present, and these patients can more easily progress to ARDS. It seems that targeting the protective tidal volume can lower adverse outcome incidence rates, even in patients without ARDS. This trial seeks to answer the question of whether adopting an ultra-protective tidal volume strategy can lead to superior primary and secondary outcomes compared to adopting a protective tidal volume strategy in patients treated by VA-ECMO. The Ultra-ECMO trial will provide an innovative mechanical ventilation strategy for VA-ECMO-supported patients for improving treatment outcomes at biological and potentially clinical levels., Clinical Trial Registration: ChiCTR2200067118., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (© 2023 Li, Chen, Hu, Sun, Zhang, Zhang, Dong, Lv, Mei and Chen.)

Purpose: This quality improvement project evaluated interventions implemented to enhance individual adherence to a lung-protective ventilation strategy and its triad: low tidal volume, PEEP ≥ 5, recruitment manoeuvres., Methods: For two years, nine anaesthesia workstations were connected to an automated cloud-based analytics software tool, which automatically recorded ventilation parameters as soon as a new patient case was opened. Four quality improvement periods were determined over the first year: baseline, intervention, no intervention, intervention + digital. In the second year, the digital strategy was continued for nine months, followed by a final "overtime" period. Baseline and no intervention periods included no training. The intervention period included both conventional and educational programs. The digital period included pop-up messages, which automatically appeared on the screen of the anaesthesia data management system when patients were intubated. The primary endpoint was provider adherence to the recommended triad., Results: From October 2018 to December 2020, 12,883 procedures were performed. Data were available for 8968 procedures: baseline (n = 2361), intervention (n = 2423), no intervention (n = 1064), intervention + digital (n = 1862), overtime (n = 1258). Age, Predicted Body Weight, ASA score, type of surgery and airway management were similar between periods. At baseline, 75.2% of procedures reported low tidal volume but only 6.9% involved the complete triad. At over time, Triad was 22% (p < 0.001). Over study period, each parameter of the Triad (RM, Vt and Peep) increased (p < 0.001 vs. baseline), driving pressure decreased although EtCO 2 and plateau pressure had not changed., Conclusion: Training with the help of digital apps improved LPV adherence over time., (Copyright © 2022 Société française d'anesthésie et de réanimation (Sfar). Published by Elsevier Masson SAS. All rights reserved.)

Objective . Protective ventilation should be based on lung mechanics and transpulmonary driving pressure (ΔPTP), as this 'hits' the lung directly. Approach . The change in end-expiratory lung volume (ΔEELV) is determined by the size of the PEEP step and the elastic properties of the lung (EL), ΔEELV/ΔPEEP. Consequently, EL can be determined as ΔPEEP/ΔEELV. By calibration of tidal inspiratory impedance change with ventilator inspiratory tidal volume, end-expiratory lung impedance changes were converted to volume changes and lung P/V curves were obtained during a PEEP trial in ten patients with acute respiratory failure. The PEEP level where ΔPTP was lowest (optimal PEEP) was determined as the steepest point of the lung P/V curve. Main results . Over-all EL ranged between 7.0-23.2 cmH 2 O/L. Optimal PEEP was 12.9 cmH 2 O (10-16) with ΔPTP of 4.1 cmH 2 O (2.8-7.6). Patients with highest EL were PEEP non-responders, where EL increased in non-dependent and dependent lung at high PEEP, indicating over-distension in all lung. Patients with lower EL were PEEP responders with decreasing EL in dependent lung when increasing PEEP. Significance . PEEP non-responders could be identified by regional lung P/V curves derived from ventilator calibrated EIT. Optimal PEEP could be determined from the equation for the lung P/V curve., (Creative Commons Attribution license.)

Background and aim Acute respiratory distress syndrome (ARDS) is a severe complication of COVID-19 and traditional ventilation strategies using ARDSNet protocol, including low tidal volumes, appear to cause barotrauma in COVID-19 patients at a higher rate than non-COVID-19 ARDS patients. The purpose of our study was to determine if COVID-19 patients with ARDS undergoing mechanical ventilation at St. Joseph's Medical Center (SJMC) developed barotrauma at a higher rate than non-COVID-19 ARDS patients. Methods and materials This study was a retrospective chart review of all patients admitted to critical care units at SJMC with COVID-19 infection and requiring mechanical ventilation from March 1, 2020 to September 30, 2020. The sample included adult patients (aged 18 and above) with the International Classification of Diseases (ICD) 10 code for COVID-19 (U07.1) and patients who were placed on mechanical ventilation for longer than 24 hours, from March 1, 2020 to September 30, 2020. Barotrauma was confirmed via radiographic imaging including chest X-ray, CT, or CT angiography (CTA).  Results One hundred and forty COVID-19 patients underwent mechanical ventilation for longer than 24 hours from March 1, 2020 to September 30, 2020 at our facility. Twenty-six COVID-19 patients (18.6%) met our inclusion criteria (development of barotrauma during hospital admission) of which 25 patients (17.9%) underwent mechanical (invasive and/or non-invasive) ventilation prior to the development of barotrauma. Around 80% of the patients were on non-invasive mechanical ventilation prior to intubation and invasive mechanical ventilation. The categorical breakdown of barotrauma was as follows: pneumothorax 65.4%, subcutaneous emphysema 61.5%, pneumomediastinum 34.6%, and pneumoperitoneum 7.7%. None of the included patients had any previous history of documented barotrauma. Prior to the time of barotrauma, 17 patients were on volume control, seven were on pressure control, and one was not on mechanical ventilation. Of the 17 patients on volume control, only one patient was above the ARDSNet guideline of 6-8 mL/kg ideal body weight (IBW). In comparison to ARDS patients at SJMC in 2019, only two out of 28 patients (7.14%) developed barotrauma during mechanical ventilation.  Conclusions Patients with COVID-19 who underwent mechanical ventilation developed barotrauma at a higher rate than traditional non-COVID-19 patients with ARDS., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2022, Mudhar et al.)

To determine whether end-expiratory lung volume measured with volumetric capnography (EELV CO2 ) can individualize positive end-expiratory pressure (PEEP) setting during laparoscopic surgery. We studied patients undergoing laparoscopic surgery subjected to Fowler (F-group; n = 20) or Trendelenburg (T-group; n = 20) positions. EELV CO2 was measured at 0° supine (baseline), during capnoperitoneum (CP) at 0° supine, during CP with Fowler (head up + 20°) or Trendelenburg (head down - 30°) positions and after CP back to 0° supine. PEEP was adjusted to preserve baseline EELV CO2 during and after CP. Baseline EELV CO2 was statistically similar to predicted FRC in both groups. At supine and CP, EELV CO2 decreased from baseline values in F-group [median and IQR 2079 (768) to 1545 (725) mL; p = 0.0001] and in T-group [2164 (789) to 1870 (940) mL; p = 0.0001]. Change in body position maintained EELV CO2 unchanged in both groups. PEEP adjustments from 5.6 (1.1) to 10.0 (2.5) cmH 2 O in the F-group (p = 0.0001) and from 5.6 (0.9) to 10.0 (2.6) cmH 2 O in T-group (p = 0.0001) were necessary to reach baseline EELV CO2 values. EELV CO2 increased close to baseline with PEEP in the F-group [1984 (600) mL; p = 0.073] and in the T-group [2175 (703) mL; p = 0.167]. After capnoperitoneum and back to 0° supine, PEEP needed to maintain EELV CO2 was similar to baseline PEEP in F-group [5.9 (1.8) cmH 2 O; p = 0.179] but slightly higher in the T-group [6.5 (2.2) cmH 2 O; p = 0.006]. Those new PEEP values gave EELV CO2 similar to baseline in the F-group [2039 (980) mL; p = 0.370] and in the T-group [2150 (715) mL; p = 0.881]. Breath-by-breath noninvasive EELV CO2 detected changes in lung volume induced by capnoperitoneum and body position and was useful to individualize the level of PEEP during laparoscopy.Trial registry: Clinicaltrials.gov NCT03693352. Protocol started 1st October 2018., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)

Purpose: To explore the feasibility of long-term application of ultraprotective ventilation with low flow ECCO 2 R support in moderate-severe ARDS patients and the reduction of mechanical power (MP) compared to lung protective ventilation., Material and Methods: ARDS patients with PaO 2 /FiO 2 < 200, PEEP of 10 cmH 2 O, tidal volume 6 ml/Kg of predicted body weight (PBW), plateau pressure > 24 cmH 2 O, MP > 17 J/min were prospectively enrolled. After 2 h tidal volume was reduced to 4-5 ml/kg, respiratory rate (RR) and PEEP were changed to maintain similar minute ventilation and mean airway pressure (MAP) to those obtained at baseline. After 2 h, ECCO 2 R support was started, RR was decreased and PEEP was increased to maintain similar PaCO 2 and MAP, respectively., Results: The only reduction of tidal volume with the increase in RR did not decrease MP. The application of low flow ECCO 2 R support allowed a reduction of RR from 25 [24-30] to 11 [9-14] bpm and MP from 18 [13-23] to 8 [7-11] J/min. During the following 5 days no changes in mechanics variables and gas exchange occurred., Conclusions: The application of low flow ECCO 2 R support with ultraprotective ventilation was feasible minimizing the MP without deterioration in oxygenation in ARDS patients., Competing Interests: Declaration of Competing Interest None., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Background: Prolonged spinal surgery in the prone position may lead to postoperative pulmonary complications (PPCs). We aimed to compare the effects of driving pressure-guided ventilation versus conventional protective ventilation on postoperative pulmonary complications in patients undergoing spinal surgery in the prone position. We hypothesized that driving pressure-guided ventilation would be associated with a decreased incidence of PPC., Methods: We enrolled 78 patients into this single-center, double-blind, randomized controlled trial. The driving pressure (DP) group (n = 40) received a tidal volume of 6 ml/kg of predicted body weight, individualized positive end-expiratory pressure (PEEP) which produced the lowest driving pressure (plateau pressure-PEEP), and a recruitment maneuver. The protective ventilation (PV) group (n = 38) received the same tidal volume and recruitment maneuver but with a fixed PEEP of 5 cm H 2 O. Our primary outcome was postoperative pulmonary complications based on Lung Ultrasound Scores (LUS) at the end of the surgery and the simplified Clinical Pulmonary Infection Score (sCPIS) on postoperative days (POD) 1 and 3., Results: DP patients had lower LUS and POD1 sCPIS than the PV group ( p  < 0.01). DP patients had lower driving pressure during the surgery than PV patients ( p  < 0.01). Perioperative arterial blood gases and hemodynamic parameters were comparable between the two groups ( p  > 0.05). The visual pain score (VAS) in postoperative days, drainage, and lengths of stay (LOS) were also similar between the two groups ( p  > 0.05)., Conclusions: Driving pressure-guided ventilation during spinal surgery with a prolonged prone patient position may reduce the incidence of early postoperative pulmonary complications, compared with conventional protective ventilation.

Mechanical ventilation is a life-saving technology, but it can also inadvertently induce lung injury and increase morbidity and mortality. Currently, there is no easy method of assessing the impact that ventilator settings have on the degree of lung inssflation. Computed tomography (CT), the gold standard for visually monitoring lung function, can provide detailed regional information of the lung. Unfortunately, it necessitates moving critically ill patients to a special diagnostic room and involves exposure to radiation. A technique introduced in the 1980s, electrical impedance tomography (EIT) can non-invasively provide similar monitoring of lung function. However, while CT provides information on the air content, EIT monitors ventilation-related changes of lung volume and changes of end expiratory lung volume (EELV). Over the past several decades, EIT has moved from the research lab to commercially available devices that are used at the bedside. Being complementary to well-established radiological techniques and conventional pulmonary monitoring, EIT can be used to continuously visualize the lung function at the bedside and to instantly assess the effects of therapeutic maneuvers on regional ventilation distribution. EIT provides a means of visualizing the regional distribution of ventilation and changes of lung volume. This ability is particularly useful when therapy changes are intended to achieve a more homogenous gas distribution in mechanically ventilated patients. Besides the unique information provided by EIT, its convenience and safety contribute to the increasing perception expressed by various authors that EIT has the potential to be used as a valuable tool for optimizing PEEP and other ventilator settings, either in the operative room and in the intensive care unit. The effects of various therapeutic interventions and applications on ventilation distribution have already been assessed with the help of EIT, and this document gives an overview of the literature that has been published in this context., (© 2022. The Author(s).)

Background: Whether targeting the driving pressure (∆P) when adjusting the tidal volume in mechanically ventilated patients with the acute respiratory distress syndrome (ARDS) may decrease the risk of ventilator-induced lung injury remains a matter of research. In this study, we assessed the effect of a ∆P-guided ventilation on the mechanical power., Methods: We prospectively included adult patients with moderate-to-severe ARDS. Positive end expiratory pressure was set by the attending physician and kept constant during the study. Tidal volume was first adjusted to target 6 ml/kg of predicted body weight (PBW-guided ventilation) and subsequently modified within a range from 4 to 10 ml/kg PBW to target a ∆P between 12 and 14 cm H 2 O. The respiratory rate was then re-adjusted within a range from 12 to 40 breaths/min until EtCO 2 returned to its baseline value (∆P-guided ventilation). Mechanical power was computed at each step., Results: Fifty-one patients were included between December 2019 and May 2021. ∆P-guided ventilation was feasible in all but one patient. The ∆P during PBW-guided ventilation was already within the target range of ∆P-guided ventilation in five (10%) patients, above in nine (18%) and below in 36 (72%). The change from PBW- to ∆P-guided ventilation was thus accompanied by an overall increase in tidal volume from 6.1 mL/kg PBW [5.9-6.2] to 7.7 ml/kg PBW [6.2-8.7], while respiratory rate was decreased from 29 breaths/min [26-32] to 21 breaths/min [16-28] (p < 0.001 for all comparisons). ∆P-guided ventilation was accompanied by a significant decrease in mechanical power from 31.5 J/min [28-35.7] to 28.8 J/min [24.6-32.6] (p < 0.001), representing a relative decrease of 7% [0-16]. With ∆P-guided ventilation, the PaO 2 /FiO 2 ratio increased and the ventilatory ratio decreased., Conclusion: As compared to a conventional PBW-guided ventilation, a ∆P-guided ventilation strategy targeting a ∆P between 12 and 14 cm H 2 O required to change the tidal volume in 90% of the patients. Such ∆P-guided ventilation significantly reduced the mechanical power. Whether this physiological observation could be associated with clinical benefit should be assessed in clinical trials., (© 2022. The Author(s).)

Objectives: Cardiopulmonary bypass generates a systemic inflammatory response. This inflammatory response is reduced if patients are ventilated during bypass, as evidenced by lower levels of postoperative circulating inflammatory mediators. However, this does not appear to make much clinical difference in adults, at least not consistently, but, to our knowledge, has never been assessed in paediatric cardiac surgery, which is the objective of this study., Methods: This is a prospective clinical study of 12 consecutive neonates operated for the correction of either transposition of the great arteries ± ventricular septal defect or aortic arch hypoplasia ± ventricular septal defect, who were ventilated during cardiopulmonary bypass. These were compared to 11 neonates with the same malformations, who had undergone the same operations but without being ventilated during bypass (historical control group)., Results: One patient from the control group died on the 15th postoperative day due to sepsis and multi-organ failure. Bypass times and cross-clamp times were similar in the 2 groups. Ventilation on bypass was associated with significantly lower postoperative serum concentrations of C-reactive protein, shorter mechanical ventilation and lower vasoactive-inotropic score. Duration of stay on intensive care unit (ICU) showed a tendency to be shorter in patients who were ventilated on bypass, but this did not reach statistical significance. There were no differences between the 2 groups with respect to postoperative mixed venous oxygen saturations and serum concentrations of lactate and troponin I., Conclusions: Mechanical ventilation during cardiopulmonary bypass in neonates improves postoperative outcome., (© The Author(s) 2022. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

Thirty years ago, the traditional approach to mechanical ventilation consisted of the normalization of PaCO2 and pH at the expense of using a tidal volume (VT) of 10-15 mL kg-1. But then, the use of 6-8 mL kg-1 became a dogma for ventilating patients either with acute respiratory distress syndrome (ARDS) or without lung disease in the operating theatre. It is currently recognized that even low tidal volumes may be excessive for some patients and insufficient for others, depending on its distribution in the aerated lung parenchyma. To carry out intraoperative protective mechanical ventilation, medical literature has focused on positive end expiratory pressure (PEEP), plateau pressure (Paw plateau), and airway driving pressure (ΔPaw). However, considering its limitations, other parameters have emerged that represent a better reflection of isolated lung stress, such as transpulmonary pressure (PL) and transpulmonary driving pressure (ΔPL). These parameters are less generalized in clinical practice due to the requirement of an oeso-phageal balloon for their measurement and therefore their cumbersome application in the operating theatre. However, its study helps in the interpretation of the rest of the ventilator pressures to optimize intraoperative mechanical ventilation. This article defines and develops protective ventilation parameters, breaks down their determinants, mentions their limitations, and offers recommendations for their use intraoperatively.

Background: During general anesthesia, mechanical ventilation can cause pulmonary damage through mechanism of ventilator-induced lung injury, which is a major cause of post-operative pulmonary complications, which varies between 5 and 33% and increases the 30-day mortality of the surgical patient significantly., Objective: The aim of this review is to analyze different variables which played a key role in the safe application of mechanical ventilation in the operating room and emergency setting., Methods: Also, we wanted to analyze different types of the population that underwent intraoperative mechanical ventilation like obese patients, pediatric and adult population and different strategies such as one lung ventilation and ventilation in trendelemburg position. The peer-reviewed articles analyzed were selected according to PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) from Pubmed/Medline, Ovid/Wiley and Cochrane Library, combining key terms such as: "pulmonary post-operative complications", "protective ventilation", "alveolar recruitment maneuvers", "respiratory compliance", "intraoperative paediatric ventilation", "best peep", "types of ventilation". Among the 230 papers identified, 150 articles were selected, after title - abstract examination and removing the duplicates, resulting in 94 articles related to mechanical ventilation in operating room and emergency setting that were analyzed., Results: Careful preoperative patient's evaluation and protective ventilation (i.e., use of low tidal volumes, adequate PEEP and alveolar recruitment maneuvers) has been shown to be effective not only in limiting alveolar de-recruitment, alveolar overdistension and lung damage, but also in reducing the onset of Pulmonary Post-operative Complications (PPCs)., Conclusion: Mechanical ventilation is like "Janus Bi-front" because it is essential for surgical procedures, for the care of critical care patients and in life-threatening conditions, but it can be harmful to the patient if continued for a long time and where an excessive dose of oxygen is administered into the lungs. Low tidal volume is associated with a minor rate of PPCs and other complications and every complication can increase the length of Stay, adding cost to NHS between 1580 € and 1650 € per day in Europe and currently the prevention of PPCS is the only weapon that we possess., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Objectives : In the context of COVID-19 pandemic, the aim of this manuscript is to provide a standard of care of patients with ARDS for non-emergency medicine trained physicians who are not customary with mechanical ventilation. Methods : We conducted a systematic review of the literature to investigate the best practice recommendations regarding the mechanical ventilation of patients with ARDS. Conclusion : We summarized the principal strategies for lung-protective ventilation of patients with ARDS. This focus is particularly addressed to physicians who are not experienced in the invasive respiratory management of ARDS patients. Nevertheless, it remains fundamental to acknowledge that new insights concerning this quickly spreading illness become available on a regular base.

Introduction : INTELLiVENT-Adaptive Support Ventilation (INTELLiVENT-ASV), an advanced closed-loop ventilation mode for use in intensive care unit (ICU) patients, is equipped with algorithms that automatically adjust settings on the basis of physiologic signals and patient's activity. Here we describe its effectiveness, safety, and efficacy in various types of ICU patients. Areas covered : A systematic search conducted in MEDLINE, EMBASE, the Cochrane Central register of Controlled Trials (CENTRAL), and in Google Scholar identified 10 randomized clinical trials. Expert opinion : Studies suggest INTELLiVENT-ASV to be an effective automated mode with regard to the titrations of tidal volume, airway pressure, and oxygen. INTELLiVENT-ASV is as safe as conventional modes. However, thus far studies have not shown INTELLiVENT-ASV to be superior to conventional modes with regard to duration of ventilation and other patient-centered outcomes. Future studies are needed to test its efficacy.

Positive end-expiratory pressure and tidal volume may have a key role for the outcome of patients with acute respiratory distress syndrome. The variety of acute respiratory distress syndrome phenotypes implies personalization of those settings. To guide personalized positive end-expiratory pressure and tidal volume, physicians need to have an in-depth understanding of the physiologic effects and bedside methods to measure the extent of these effects. In the present article, a step-by-step physiologic approach to select personalized positive end-expiratory pressure and tidal volume at the bedside is described., Data Sources: The present review is a critical reanalysis of the traditional and latest literature on the topic., Study Selection: Relevant clinical and physiologic studies on positive end-expiratory pressure and tidal volume setting were reviewed., Data Extraction: Reappraisal of the available physiologic and clinical data., Data Synthesis: Positive end-expiratory pressure is aimed at stabilizing alveolar recruitment, thus reducing the risk of volutrauma and atelectrauma. Bedside assessment of the potential for lung recruitment is a preliminary step to recognize patients who benefit from higher positive end-expiratory pressure level. In patients with higher potential for lung recruitment, positive end-expiratory pressure could be selected by physiology-based methods balancing recruitment and overdistension. In patients with lower potential for lung recruitment or in shock, positive end-expiratory pressure could be maintained in the 5-8 cm H 2 O range. Tidal volume induces alveolar recruitment and improves gas exchange. After setting personalized positive end-expiratory pressure, tidal volume could be based on lung inflation (collapsed lung size) respecting safety thresholds of static and dynamic lung stress. Positive end-expiratory pressure and tidal volume could be kept stable for some hours in order to allow early recognition of changes in the clinical course of acute respiratory distress syndrome but also frequently reassessed to avoid crossing of safety thresholds., Conclusions: The setting of personalized positive end-expiratory pressure and tidal volume based on sound physiologic bedside measures may represent an effective strategy for treating acute respiratory distress syndrome patients., (Copyright © 2021 The Authors. Published by Wolters Kluwer Health, Inc. on behalf of the Society of Critical Care Medicine.)

Background: It is uncertain whether the association of the intraoperative driving pressure (ΔP) with postoperative pulmonary complications (PPCs) depends on the surgical approach during abdominal surgery. Our primary objective was to determine and compare the association of time-weighted average ΔP (ΔP TW ) with PPCs. We also tested the association of ΔP TW with intraoperative adverse events., Methods: Posthoc retrospective propensity score-weighted cohort analysis of patients undergoing open or closed abdominal surgery in the 'Local ASsessment of Ventilatory management during General Anaesthesia for Surgery' (LAS VEGAS) study, that included patients in 146 hospitals across 29 countries. The primary endpoint was a composite of PPCs. The secondary endpoint was a composite of intraoperative adverse events., Results: The analysis included 1128 and 906 patients undergoing open or closed abdominal surgery, respectively. The PPC rate was 5%. ΔP was lower in open abdominal surgery patients, but ΔP TW was not different between groups. The association of ΔP TW with PPCs was significant in both groups and had a higher risk ratio in closed compared to open abdominal surgery patients (1.11 [95%CI 1.10 to 1.20], P <  0.001 versus 1.05 [95%CI 1.05 to 1.05], P <  0.001; risk difference 0.05 [95%CI 0.04 to 0.06], P <  0.001). The association of ΔP TW with intraoperative adverse events was also significant in both groups but had higher odds ratio in closed compared to open abdominal surgery patients (1.13 [95%CI 1.12- to 1.14], P <  0.001 versus 1.07 [95%CI 1.05 to 1.10], P <  0.001; risk difference 0.05 [95%CI 0.030.07], P <  0.001)., Conclusions: ΔP is associated with PPC and intraoperative adverse events in abdominal surgery, both in open and closed abdominal surgery., Trial Registration: LAS VEGAS was registered at clinicaltrials.gov (trial identifier NCT01601223 ).

Background: Limiting tidal volume (V T ), plateau pressure, and driving pressure is essential during the acute respiratory distress syndrome (ARDS), but may be challenging when brain injury coexists due to the risk of hypercapnia. Because lowering dead space enhances CO 2 clearance, we conducted a study to determine whether and to what extent replacing heat and moisture exchangers (HME) with heated humidifiers (HH) facilitate safe V T lowering in brain-injured patients with ARDS., Methods: Brain-injured patients (head trauma or spontaneous cerebral hemorrhage with Glasgow Coma Scale at admission < 9) with mild and moderate ARDS received three ventilatory strategies in a sequential order during continuous paralysis: (1) HME with V T to obtain a PaCO 2 within 30-35 mmHg (HME1); (2) HH with V T titrated to obtain the same PaCO 2 (HH); and (3) HME1 settings resumed (HME2). Arterial blood gases, static and quasi-static respiratory mechanics, alveolar recruitment by multiple pressure-volume curves, intracranial pressure, cerebral perfusion pressure, mean arterial pressure, and mean flow velocity in the middle cerebral artery by transcranial Doppler were recorded. Dead space was measured and partitioned by volumetric capnography., Results: Eighteen brain-injured patients were studied: 7 (39%) had mild and 11 (61%) had moderate ARDS. At inclusion, median [interquartile range] PaO 2 /FiO 2 was 173 [146-213] and median PEEP was 8 cmH 2 O [5-9]. HH allowed to reduce V T by 120 ml [95% CI: 98-144], V T /kg predicted body weight by 1.8 ml/kg [95% CI: 1.5-2.1], plateau pressure and driving pressure by 3.7 cmH 2 O [2.9-4.3], without affecting PaCO 2 , alveolar recruitment, and oxygenation. This was permitted by lower airway (- 84 ml [95% CI: - 79 to - 89]) and total dead space (- 86 ml [95% CI: - 73 to - 98]). Sixteen patients (89%) showed driving pressure equal or lower than 14 cmH 2 O while on HH, as compared to 7 (39%) and 8 (44%) during HME1 and HME2 (p < 0.001). No changes in mean arterial pressure, cerebral perfusion pressure, intracranial pressure, and middle cerebral artery mean flow velocity were documented during HH., Conclusion: The dead space reduction provided by HH allows to safely reduce V T without modifying PaCO 2 nor cerebral perfusion. This permits to provide a wider proportion of brain-injured ARDS patients with less injurious ventilation.

Aim: To describe the correlation between the inspiratory esophageal and transdiaphragmatic pressure swings (ΔPes and ΔPdi), easily measured indices of inspiratory effort, with the gold-standard, the transdiaphragmatic pressure time product (PTP Pdi /min), and assess the accuracy of swing pressures in predicting very high or low effort., Method: Retrospective analysis of data from patients enrolled in four previous studies. ROC curves of ΔPes and ΔPdi values for specific PTP Pdi /min thresholds (50, 150, 200 cmH 2 O × sec/min) were constructed, and the diagnostic accuracy of different thresholds of swing values were computed., Results: A threshold of inspiratory ΔP<7cmH 2 O can be used to identify most patients with low effort, as lower ΔP thresholds have low sensitivity. Thresholds of inspiratory ΔP>14-18cmH 2 O can be used to identify patients with very high inspiratory effort (PTP Pdi /min> 200 cmH 2 O × sec/min)., Conclusions: The results of this study can help clinicians better select and interpret thresholds of ΔP to evaluate inspiratory effort., (Copyright © 2020 Elsevier B.V. All rights reserved.)

Neuromuscular blocking agents (NMBAs) inhibit patient-initiated active breath and the risk of high tidal volumes and consequent high transpulmonary pressure swings, and minimize patient/ ventilator asynchrony in acute respiratory distress syndrome (ARDS). Minimization of volutrauma and ventilator-induced lung injury (VILI) results in a lower incidence of barotrauma, improved oxygenation and a decrease in circulating proinflammatory markers. Recent randomized clinical trials did not reveal harmful muscular effects during a short course of NMBAs. The use of NMBAs should be considered during the early phase of severe ARDS for patients to facilitate lung protective ventilation or prone positioning only after optimising mechanical ventilation and sedation. The use of NMBAs should be integrated in a global strategy including the reduction of tidal volume, the rational use of PEEP, prone positioning and the use of a ventilatory mode allowing spontaneous ventilation as soon as possible. Partial neuromuscular blockade should be evaluated in future trials.

Background: Ensuring that lung-protective ventilation is achieved at scale is challenging in perioperative practice. Fully automated ventilation may be more effective in delivering lung-protective ventilation. Here, we compared automated lung-protective ventilation with conventional ventilation after elective cardiac surgery in haemodynamically stable patients., Methods: In this single-centre investigator-led study, patients were randomly assigned at the end of cardiac surgery to receive either automated (adaptive support ventilation) or conventional ventilation. The primary endpoint was the proportion of postoperative ventilation time characterised by exposure to predefined optimal, acceptable, and critical (injurious) ventilatory parameters in the first three postoperative hours. Secondary outcomes included severe hypoxaemia (Spo 2 <85%) and resumption of spontaneous breathing. Data are presented as mean (95% confidence intervals [CIs])., Results: We randomised 220 patients (30.4% females; age: 62-76 yr). Subjects randomised to automated ventilation (n=109) spent a 29.7% (95% CI: 22.1-37.4) higher mean proportion of postoperative ventilation time receiving optimal postoperative ventilation after surgery (P<0.001) compared with subjects receiving conventional postoperative ventilation (n=111). Automated ventilation also reduced the proportion of postoperative ventilation time that subjects were exposed to injurious ventilatory settings by 2.5% (95% CI: 1-4; P=0.003). Severe hypoxaemia was less likely in subjects randomised to automated ventilation (risk ratio: 0.26 [0.22-0.31]; P<0.01). Subjects resumed spontaneous breathing more rapidly when randomised to automated ventilation (hazard ratio: 1.38 [1.05-1.83]; P=0.03)., Conclusions: Fully automated ventilation in haemodynamically stable patients after cardiac surgery optimised lung-protective ventilation during postoperative ventilation, with fewer episodes of severe hypoxaemia and an accelerated resumption of spontaneous breathing., Clinical Trial Registration: NCT03180203., (Copyright © 2020 British Journal of Anaesthesia. Published by Elsevier Ltd. All rights reserved.)

Background This is a retrospective case series, and the main objective is to describe the epidemiology, clinical features, and outcomes of pediatric acute respiratory distress syndrome in patients at moderate altitude. Methods Children from the Pediatric Intensive Care Unit (PICU) at the Fundación Cardioinfantil, hospitalized with acute respiratory distress syndrome, were prospectively enrolled from March 2009 to March 2014. We evaluated the demographic data, mechanical ventilation, gas exchange, hemodynamics, and multiorgan dysfunction. Results During the study period, 88 patients met the inclusion criteria. Bronchiolitis and pneumonia were the most common causes of acute respiratory distress syndrome. The overall mortality rate was 19.5%. At the beginning of the study, the average relation between blood pressure and the fraction of inspired oxygen (Pa/Fi) was 130.3 ± 52.2; tidal volume was 7.94 ± 1.7 ml/kg, the plateau pressure 25.3 ± 5.09 cmH 2 O, and positive end-expiratory pressure was 7.2 ± 3.2 cmH 2 O. After 24 hours, the mortality rate in the group with severe acute respiratory distress syndrome (Pa/Fi <100) was 46.7%, in the moderate acute respiratory distress syndrome group (Pa/Fi 100-200) it was 11.9%, and finally in the mild acute respiratory distress syndrome group (Pa/Fi 200-300) the mortality was 25%. This study found a relation between serum lactate value and positive end-expiratory pressure and mortality (p = 0.02 and 0.0013). Conclusions This study shows that pediatric acute respiratory distress syndrome patients at moderate altitudes have similar clinical behavior, including mortality rate, to those at low altitudes. However, Pa/Fi is not a good predictor of mortality for patients with mild and moderate acute respiratory distress syndrome., Competing Interests: The authors have declared that no competing interests exist., (Copyright © 2020, Chacón et al.)

SARS-coV2 infection may induce a severe pneumonia that may lead to an acute respiratory distress syndrome. Hypoxaemia is the key symptom of the disease but other features are different such as pulmonary compliance that is most of the time initially normal. The mechanisms of the pulmonary damage are not completely understood. A new ventilation strategy has been set up to prevent ventilator induced lung injury (VILI)., (© 2020 Published by Elsevier Masson SAS.)

Background: The lungs of pediatric patients are subjected to tidal derecruitment during mechanical ventilation and in contrast to adult patients this unfavorable condition cannot be resolved with small c increases. This raises the question if higher end-expiratory pressure increases or recruitment maneuvers may resolve tidal derecruitment in pediatric patients., Aims: We hypothesized that higher PEEP resolves tidal derecruitment in pediatric patients and that recruitment maneuvers between the pressure changes support the improvement of respiratory system mechanics., Methods: The effects of end-expiratory pressure changes from 3 to 7 cmH 2 O and vice versa without and with intermediate recruitment maneuvers on respiratory system mechanics and regional ventilation were investigated in 57 mechanically ventilated pediatric patients. The intratidal respiratory system compliance was determined from volume and pressure data before and after PEEP changes and categorized to indicate tidal derecruitment., Results: Tidal derecruitment occurred comparably frequently at PEEP 3 cmH 2 O without (13 out of 14 cases) and with recruitment maneuver (14 out of 14 cases) and at PEEP 7 cmH 2 O without (13 out of 14 cases) and with recruitment maneuver (13 out of 15 cases)., Conclusions: We conclude that contrary to our hypothesis, PEEP up to 7 cmH 2 O is not sufficient to resolve tidal derecruitment and that recruitment maneuvers may be dispensable in mechanically ventilated pediatric patients., (© 2020 The Authors. Pediatric Anesthesia published by John Wiley & Sons Ltd.)

Background: The driving pressure of the respiratory system is a valuable indicator of global lung stress during passive mechanical ventilation. Monitoring lung stress in assisted ventilation is indispensable, but achieving passive conditions in spontaneously breathing patients to measure driving pressure is challenging. The accuracy of the morphology of airway pressure (Paw) during end-inspiratory occlusion to assure passive conditions during pressure support ventilation has not been examined., Methods: Retrospective analysis of end-inspiratory occlusions obtained from critically ill patients during pressure support ventilation. Flow, airway, esophageal, gastric, and transdiaphragmatic pressures were analyzed. The rise of gastric pressure during occlusion with a constant/decreasing transdiaphragmatic pressure was used to identify and quantify the expiratory muscle activity. The Paw during occlusion was classified in three patterns, based on the differences at three pre-defined points after occlusion (0.3, 1, and 2 s): a "passive-like" decrease followed by plateau, a pattern with "clear plateau," and an "irregular rise" pattern, which included all cases of late or continuous increase, with or without plateau., Results: Data from 40 patients and 227 occlusions were analyzed. Expiratory muscle activity during occlusion was identified in 79% of occlusions, and at all levels of assist. After classifying occlusions according to Paw pattern, expiratory muscle activity was identified in 52%, 67%, and 100% of cases of Paw of passive-like, clear plateau, or irregular rise pattern, respectively. The driving pressure was evaluated in the 133 occlusions having a passive-like or clear plateau pattern in Paw. An increase in gastric pressure was present in 46%, 62%, and 64% of cases at 0.3, 1, and 2 s, respectively, and it was greater than 2 cmH 2 O, in 10%, 20%, and 15% of cases at 0.3, 1, and 2 s, respectively., Conclusions: The pattern of Paw during an end-inspiratory occlusion in pressure support cannot assure the absence of expiratory muscle activity and accurate measurement of driving pressure. Yet, because driving pressure can only be overestimated due to expiratory muscle contraction, in everyday practice, a low driving pressure indicates an absence of global lung over-stretch. A measurement of high driving pressure should prompt further diagnostic workup, such as a measurement of esophageal pressure.

Protective ventilation is a prevailing ventilatory strategy these days and is comprised of small tidal volume, limited inspiratory pressure, and application of positive end-expiratory pressure (PEEP). However, several retrospective studies recently suggested that tidal volume, inspiratory pressure, and PEEP are not related to patient outcomes, or only related when they influence the driving pressure. Therefore, this review introduces the concept of driving pressure and looks into the possibility of driving pressure-guided ventilation as a new ventilatory strategy, especially in thoracic surgery where postoperative pulmonary complications are common, and thus, lung protection is of utmost importance.

The prevention of ventilator-associated lung injury (VALI) and postoperative pulmonary complications (PPC) is of paramount importance for improving outcomes both in the operating room and in the intensive care unit (ICU). Protective respiratory support includes a wide spectrum of interventions to decrease pulmonary stress-strain injuries. The motto 'low tidal volume for all' should become routine, both during major surgery and in the ICU, while application of a high positive end-expiratory pressure (PEEP) strategy and of alveolar recruitment maneuvers requires a personalized approach and requires further investigation. Patient self-inflicted lung injury is an important type of VALI, which should be diagnosed and mitigated at the early stage, during restoration of spontaneous breathing. This narrative review highlights the strategies used for protective positive pressure ventilation. The emerging concepts of damaging energy and power, as well as pathways to personalization of the respiratory settings, are discussed in detail. In the future, individualized approaches to protective ventilation may involve multiple respiratory settings extending beyond low tidal volume and PEEP, implemented in parallel with quantifying the risk of VALI and PPC.

Objectives: Stroke volume variation (SVV) has been used to predict fluid responsiveness. The authors hypothesized the changes in SVV induced by passive leg raising (PLR) might be an indicator of fluid responsiveness in patients with protective ventilation after cardiac surgery., Design: A prospective single-center observational study., Setting: A single cardiac surgery intensive care unit at a tertiary hospital., Participants: A total of 123 patients undergoing cardiac surgery with hemodynamic instability. Tidal volume was set between 6 and 8 mL/kg of ideal body weight., Interventions: PLR maneuver, fluid challenge., Measurements and Main Results: SVV was continuously recorded using pulse contour analysis before and immediately after a PLR test and after fluid challenge (500 mL of colloid given over 30 min). Sixty-three (51.22%) patients responded to fluid challenge, in which PLR and fluid challenge significantly increased the SV and decreased the SVV. The decrease in SVV induced by PLR was correlated with the SV changes induced by fluid challenge. A 4% decrease in the SVV induced by PLR-discriminated responders to fluid challenge with an area under the curve of 0.90. The gray zone identified a range of SVV changes induced by PLR (between -3.94% and -2.91%) for which fluid responsiveness could not be predicted reliably. The gray zone included 15.45% of the patients. The SVV at baseline predicted fluid responsiveness with an area under the curve of 0.72., Conclusions: Changes in the SVV induced by PLR predicted fluid responsiveness in cardiac surgical patients with protective ventilation., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objective: Ventilation strategies aiming at prevention of ventilator-induced lung injury (VILI), including low tidal volumes (V T ) and use of positive end-expiratory pressures (PEEP) are increasingly used in critically ill patients. It is uncertain whether ventilation practices changed in a similar way in burn patients. Our objective was to describe applied ventilator settings and their relation to development of VILI in burn patients., Data Sources: Systematic search of the literature in PubMed and EMBASE using MeSH, EMTREE terms and keywords referring to burn or inhalation injury and mechanical ventilation., Study Selection: Studies reporting ventilator settings in adult or pediatric burn or inhalation injury patients receiving mechanical ventilation during the ICU stay., Data Extraction: Two authors independently screened abstracts of identified studies for eligibility and performed data extraction., Data Synthesis: The search identified 35 eligible studies. V T declined from 14 ml/kg in studies performed before to around 8 ml/kg predicted body weight in studies performed after 2006. Low-PEEP levels (<10 cmH 2 O) were reported in 70% of studies, with no changes over time. Peak inspiratory pressure (PIP) values above 35 cmH 2 O were frequently reported. Nevertheless, 75% of the studies conducted in the last decade used limited maximum airway pressures (≤35 cmH 2 O) compared to 45% of studies conducted prior to 2006. Occurrence of barotrauma, reported in 45% of the studies, ranged from 0 to 29%, and was more frequent in patients ventilated with higher compared to lower airway pressures., Conclusion: This systematic review shows noticeable trends of ventilatory management in burn patients that mirrors those in critically ill non-burn patients. Variability in available ventilator data precluded us from drawing firm conclusions on the association between ventilator settings and the occurrence of VILI in burn patients., (Copyright © 2019 Elsevier Ltd and ISBI. All rights reserved.)

Background: Prone position (PP) is highly recommended in moderate-to-severe ARDS. However, the optimal duration of PP sessions remains unclear. We searched to evaluate the time required to obtain the maximum physiological effect, and to search for parameters related to patient survival in PP., Methods and Results: It was a prospective, monocentric, physiological study. We included in the study all prone-positioned patients in our ICU between June 2016 and January 2018. Pulmonary mechanics, data from volumetric capnography and arterial blood gas were recorded before prone positioning, 2 h after proning, before return to a supine position (SP) and 2 h after return to SP. Dynamic parameters were recorded before proning and every 30 min during the session until 24 h. 103 patients (ARDS 95%) were included performing 231 PP sessions with a mean length of 21.5 ± 5 h per session. They presented a significant increase in pH, static compliance and P a O 2 /F i O 2 with a significant decrease in P a CO 2 , P plat , phase 3 slope of the volumetric capnography, P et CO 2 , V D /V T-phy and ΔP. The beneficial physiological effects continued after 16 h of PP and at least up to 24 h in some patients. The evolution of the respiratory parameters during the first session and also during the pooled sessions did not find any predictor of response to PP, whether before, during or 2 h after the return in SP., Conclusions: PP sessions should be prolonged at least 24 h and be extended in the event that the P a O 2 /F i O 2 ratio at 24 h remains below 150, especially since no criteria can predict which patient will benefit or not from it. Trial registration The trial has been registered on 28 June 2016 in ClinicalTrials.gov (NCT02816190) (https://clinicaltrials.gov/ct2/show/NCT02816190?term=propocap&rank=1).

Invasive and non-invasive mechanical ventilation (MV) continues to be the most significant life support method. It is, however, coupled with many risks. Historically, concepts of MV did focus on improving the arterial blood gas results rather than preventing harmful side-effects of positive pressure ventilation. Since then, multiple studies exploring this matter emerged and led to the protective MV concept. The golden mean between assuring the best oxygenation and limiting the ventilator-induced lung injury (VILI) is still a matter of debate. These considerations are especially impactful while treating patients with adult respiratory distress syndrome (ARDS), where the limitation of MV's negative effect is specifically important. This paper explores the protective ventilation concept and clinical implications of the latter.

Patients undergoing emergency surgery may present with the acute respiratory distress syndrome (ARDS) or develop this syndrome postoperatively. The incidence of ARDS in the postoperative period is relatively low, but the impact of ARDS on patient outcomes and healthcare costs is relevant Aakre et.al (Mayo Clin Proc 89:181-9, 2014).The development of ARDS as a postoperative pulmonary complication (PPC) is associated with prolonged hospitalisation, longer duration of mechanical ventilation, increased intensive care unit length of stay and high morbidity and mortality Ball et.al (Curr Opin Crit Care 22:379-85, 2016). In order to mitigate the risk of ARDS after surgery, the anaesthetic management and protective mechanical ventilation strategies play an important role. In particular, a careful integration of general anaesthesia with neuraxial or locoregional techniques might promote faster recovery and reduce opioid consumption. In addition, the use of low tidal volume, minimising plateau pressure and titrating a low-moderate PEEP level based on the patient's need can improve outcome and reduce intraoperative adverse events. Moreover, perioperative management of ARDS patients includes specific anaesthesia and ventilator settings, hemodynamic monitoring, moderately restrictive fluid administration and pain control.The aim of this review is to provide an overview and evidence- and opinion-based recommendations concerning the management of patients at risk of and with ARDS who undergo emergency surgical procedures.

Background: Introducing mathematically derived variability (MVV) into the otherwise monotonous conventional mechanical ventilation has been suggested to improve lung recruitment and gas exchange. Although the application of a ventilation pattern based on variations in physiological breathing (PVV) is beneficial for healthy lungs, its value in the presence of acute respiratory distress syndrome (ARDS) has not been characterized. We therefore aimed at comparing conventional pressure-controlled ventilation with (PCS) or without regular sighs (PCV) to MVV and PVV at two levels of positive end-expiratory pressure (PEEP) in a model of severe ARDS., Methods: Anesthetised rabbits ( n = 54) were mechanically ventilated and severe ARDS (PaO 2 /FiO 2 ≤ 150 mmHg) was induced by combining whole lung lavage, i.v. endotoxin and injurious ventilation. Rabbits were then randomly assigned to be ventilated with PVV, MVV, PCV, or PCS for 5 h while maintaining either 6 or 9 cmH 2 O PEEP. Ventilation parameters, blood gas indices and respiratory mechanics (tissue damping, G, and elastance, H) were recorded hourly. Serum cytokine levels were assessed with ELISA and lung histology was analyzed., Results: Although no progression of lung injury was observed after 5 h of ventilation at PEEP 6 cmH 2 O with PVV and PCV, values for G (58.8 ± 71.1[half-width of 95% CI]% and 40.8 ± 39.0%, respectively), H (54.5 ± 57.2%, 50.7 ± 28.3%), partial pressure of carbon-dioxide (PaCO 2 , 43.9 ± 23.8%, 46.2 ± 35.4%) and pH (-4.6 ± 3.3%, -4.6 ± 2.2%) worsened with PCS and MVV. Regardless of ventilation pattern, application of a higher PEEP improved lung function and precluded progression of lung injury and inflammation. Histology lung injury scores were elevated in all groups with no difference between groups at either PEEP level., Conclusion: At moderate PEEP, variable ventilation based on a pre-recorded physiological breathing pattern protected against progression of lung injury equally to the conventional pressure-controlled mode, whereas mathematical variability or application of regular sighs caused worsening in lung mechanics. This outcome may be related to the excessive increases in peak inspiratory pressure with the latter ventilation modes. However, a greater benefit on respiratory mechanics and gas exchange could be obtained by elevating PEEP, compared to the ventilation mode in severe ARDS.

The incidence of intra-abdominal hypertension (IAH) is high and still underappreciated by critical care physicians throughout the world. One in four to one in three patients will have IAH on admission, while one out of two will develop IAH within the first week of Intensive Care Unit stay. IAH is associated with high morbidity and mortality. Although considerable progress has been made over the past decades, some important questions remain regarding the optimal ventilation management in patients with IAH. An important first step is to measure intra-abdominal pressure (IAP). If IAH (IAP > 12 mmHg) is present, medical therapies should be initiated to reduce IAP as small reductions in intra-abdominal volume can significantly reduce IAP and airway pressures. Protective lung ventilation with low tidal volumes in patients with respiratory failure and IAH is important. Abdominal-thoracic pressure transmission is around 50%. In patients with IAH, higher positive end-expiratory pressure (PEEP) levels are often required to avoid alveolar collapse but the optimal PEEP in these patients is still unknown. During recruitment manoeuvres, higher opening pressures may be required while closely monitoring oxygenation and the haemodynamic response. During lung-protective ventilation, whilst keeping driving pressures within safe limits, higher plateau pressures than normally considered might be acceptable. Monitoring of the respiratory function and adapting the ventilatory settings during anaesthesia and critical care are of great importance. This review will focus on how to deal with the respiratory derangements in critically ill patients with IAH.

Extracorporeal CO 2 removal (ECCO 2 R) is intended to facilitate lung protective ventilation in patients with hypercarbia. The combination of continuous renal replacement therapy (CRRT) and minimal-flow ECCO 2 R offers a promising concept for patients in need of both. We hypothecated that this system is able to remove enough CO 2 to facilitate lung protective ventilation in mechanically ventilated patients. In 11 ventilated patients with acute renal failure who received either pre- or postdilution CRRT, minimal-flow ECCO 2 R was added to the circuit. During 6 h of combined therapy, CO 2 removal and its effect on facilitation of lung-protective mechanical ventilation were assessed. Ventilatory settings were kept in assisted or pressure-controlled mode allowing spontaneous breathing. With minimal-flow ECCO 2 R significant decreases in minute ventilation, tidal volume and paCO 2 were found after one and three but not after 6 h of therapy. Nevertheless, no significant reduction in applied force was found at any time during combined therapy. CO 2 removal was 20.73 ml CO 2 /min and comparable between pre- and postdilution CRRT. Minimal-flow ECCO 2 R in combination with CRRT is sufficient to reduce surrogates for lung-protective mechanical ventilation but was not sufficient to significantly reduce force applied to the lung. Causative might be the absolute amount of CO 2 removal of only about 10% of resting CO 2 production in an adult as we found. The benefit of applying minimal flow ECCO 2 R in an uncontrolled setting of mechanical ventilation might be limited.