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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 (ECCO2R) 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 ECCO2R, and using ECCO2R 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 ECCO2R substantially increased the probability of achieving targets in both PSV and PAV+ (85% vs. 84%). ECCO2R alone without ventilation or sedation achieved LDP targets in 9%. The main determinants of success without ECCO2R 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 ECCO2R in combination with mechanical ventilation and sedation to achieve LDP targets. ECCO2R increased the probability of achieving LDP targets in patients with intermediate degrees of derangement in elastance and ventilatory ratio.

Introduction The primary objective of this study was to evaluate the association between the U.S. Air Force Critical Care Air Transport (CCAT) provider operational experience with compliance for lung protective ventilation (LPV) volumes recommended by Acute Respiratory Distress Syndrome Clinical Network guidelines. Materials and Methods We performed a retrospective cohort study of CCAT providers transporting combat casualties requiring mechanical ventilation from the Middle East to Germany from 2007 to 2012. We reviewed CCAT medical records from 2007 to 2012 for the total number of patient transports by CCAT physicians and respiratory care practitioners (RCPs). Center for Sustainment of Trauma and Readiness Skills Cincinnati process improvement questionnaire data described provider demographics and clinical backgrounds. We linked these data to patient demographics and in-flight ventilation management from a prior CCAT cohort study. Patient inclusion criteria included transport by CCAT from the Middle East to Germany for traumatic injury requiring mechanical ventilation between 2007 and 2012. We excluded patients with no documented height or tidal volume. LPV compliance was defined as tidal volumes ≤8 mL/kg of predicted body weight during en route critical care transport. We performed a logistic regression analysis. This study was reviewed and approved by the 59th Medical Wing institutional review board (IRB). Results We analyzed 491 patient transports conducted by 71 (RCPs and 84 physicians. Patients had a median age of 25 years (IQR 22-30), 98% were male, median injury severity score was 24 (IQR 17-34), and median preflight PaO2/FiO2 was 285 (IQR 220-365). Median experience was 26 missions (IQR 13-40) for RCPs and 23 missions (IQR 12-38) for physicians. All in-flight tidal volumes were LPV compliant in 58.3% of missions. Unadjusted analysis showed higher LPV compliance for RCPs with in-garrison critical care experience. Multivariate models did not find an association between missions flown and LPV compliance but did demonstrate a positive association with physician specialty of medical intensivist (OR 3.0, 95% CI 1.6-5.7) and a negative association with flights in 2008 (OR 0.4, 95% CI 0.2-0.7) for LPV compliance. Conclusion No association was found between number of missions flown by CCAT providers and lung protective tidal volume compliance. Linkage of multiple data sources enabled investigation of clinical and operational currency associations with a care quality metric compliance in the combat en route care environment. Future studies should evaluate the impact of ongoing CCAT training and quality improvement interventions on LPV compliance. [ABSTRACT FROM AUTHOR]

Abstract 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 (ECCO2R) 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 ECCO2R, and using ECCO2R 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 ECCO2R substantially increased the probability of achieving targets in both PSV and PAV+ (85% vs. 84%). ECCO2R alone without ventilation or sedation achieved LDP targets in 9%. The main determinants of success without ECCO2R 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 ECCO2R in combination with mechanical ventilation and sedation to achieve LDP targets. ECCO2R increased the probability of achieving LDP targets in patients with intermediate degrees of derangement in elastance and ventilatory ratio.

Abstract Mechanical ventilation is an important life-saving therapy for general anesthesia and critically ill patients, but ventilation itself may be accompanied with lung injury. Ventilator-induced lung injury (VILI) exacerbates pre-existing lung disease, leading to poor clinical outcomes. Especially for patients undergoing cardiothoracic surgery and receiving one-lung ventilation (OLV), optimizing the parameters of OLV is closely related to their prognosis. It is not clear what is the best strategy to minimize VILI through adjusting ventilation parameters, including tidal volume, positive end expiratory pressure and driving pressure, etc. Different parameters, in combination, are responsible for VILI. Protective ventilation strategies, aiming to reduce postoperative pulmonary complications, have been discussed in many clinical studies and different opinions have been raised. This review addresses the pathogenesis of VILI and focus on the OLV management and better protective OLV strategies during thoracic surgery.

Mechanical ventilation is an important life-saving therapy for general anesthesia and critically ill patients, but ventilation itself may be accompanied with lung injury. Ventilator-induced lung injury (VILI) exacerbates pre-existing lung disease, leading to poor clinical outcomes. Especially for patients undergoing cardiothoracic surgery and receiving one-lung ventilation (OLV), optimizing the parameters of OLV is closely related to their prognosis. It is not clear what is the best strategy to minimize VILI through adjusting ventilation parameters, including tidal volume, positive end expiratory pressure and driving pressure, etc. Different parameters, in combination, are responsible for VILI. Protective ventilation strategies, aiming to reduce postoperative pulmonary complications, have been discussed in many clinical studies and different opinions have been raised. This review addresses the pathogenesis of VILI and focus on the OLV management and better protective OLV strategies during thoracic surgery. [ABSTRACT FROM AUTHOR]

Background: Cardiopulmonary bypass (CPB) is a crucial component of cardiac surgery, yet it often leads to postoperative pulmonary dysfunction (PPD). Various modes of ventilation during CPB have been employed, but their comparative effects on PPD remain unclear. Materials and Methods: This study aimed to compare different modes of ventilation--namely, conventional ventilation (CV) and protective ventilation (PV)--during CPB and assess their impact on PPD. A total of 100 patients undergoing cardiac surgery were randomly assigned to either the CV group or the PV group. Demographic data, intraoperative variables, and postoperative outcomes were recorded. PPD was assessed through pulmonary function tests (PFTs) postoperatively. Results: In the CV group, PPD was observed in 45% of patients, with a mean reduction in forced vital capacity (FVC) of 25% and forced expiratory volume in one second (FEV1) of 30%. Contrastingly, in the PV group, PPD occurred in only 20% of patients, with a mean reduction in FVC of 15% and FEV1 of 20%. The incidence of pneumonia was also significantly lower in the PV group (p < 0.05). Conclusion: Protective ventilation during CPB appears to mitigate the incidence and severity of postoperative pulmonary dysfunction compared to conventional ventilation. Employing protective ventilation strategies may contribute to improved postoperative outcomes and reduced pulmonary complications following cardiac surgery. [ABSTRACT FROM AUTHOR]

BackgroundThe 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.MethodsIn 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 H2O. 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.ResultsA 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 H2O. As targeted PMI increased, pressure support settings decreased significantly from a median (interquartile range) of 11 (10–12) to 5 (4–6) cm H2O (p

Abstract 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

Abstract 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.

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 (Pcond) method, which compare the Pcond—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 Pcond 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 Pcond method was compared with the standard low-flow method. Measurements and main results: Bench assessments validated the Pcond method proof-of-concept. Sensitivity and specificity of the Pcond method for AOP detection were 93% and 91%, respectively. AOP obtained by Pcond and standard low-flow methods strongly correlated (r = 0.84, p < 0.001). Changes in SpO2 were significantly lower during Pcond than during standard method (p < 0.001). Conclusion: Determination of Pcond during constant-flow assist control ventilation may permit to easily and safely detect and measure AOP. [ABSTRACT FROM AUTHOR]

OBJECTIVE: This study aimed to evaluate the lung protection effect of an individualized protective ventilation strategy based on lung impedance tomography (EIT) technology in patients with partial pulmonary resection. PATIENTS AND METHODS: Eighty patients of any gender, American Society of Anesthesiologists (ASA) classification I-II, age 30-64 years and body mass index (BMI) 18-28 kg/m² who underwent elective thoracoscopic partial lung resection were selected and divided into 2 groups (n=40) using the random number table method: [positive end-expiratory pressure (PEEP) by electrical impedance tomography (EIT)] PEEPEIT group (experimental group) and control group. The PEEPEIT group used volume-controlled ventilation after one-lung ventilation, setting a tidal volume of 6 ml/kg and titrating the optimal PEEP value by EIT. Group C used volume-controlled ventilation after one-lung ventilation, setting a tidal volume of 6 ml/kg and a PEEP of 5 cm H2O. Clinical data were collected and recorded at 5 min after double lung ventilation (T0), single lung ventilation, 30 min after PEEP setting (T1), 60 min after PEEP setting (T2), the end of surgery, 10 min after resumption of double lung ventilation (T3) and 10 min after removal of the tracheal tube (T4), and serum surface active substance-associated protein-A (SP-A) concentrations were measured at T0, T3 and 1 d after surgery (T5). RESULTS: PEEP values were higher in the PEEPEIT group than in the control group at T1 and T2 (p-value <0.05); oxygenation index (OI) was higher in the PEEPEIT group compared to the control group at T2 and T3 (p-value <0.05); pulmonary dynamic compliance (Cdyn) was higher in the PEEPEIT group compared to the control group at T1 and T2 (p-value <0.05); intrapulmonary shunt rate (Qs/Qt) was lower in the PEEPEIT group compared to the control group at T1, T2 and at T3, the intrapulmonary shunt rate (Qs/Qt) was reduced in the PEEPEIT group compared to group C (p-value <0.05); at T5, the SP-A protein was reduced in the PEEPEIT group compared to group C. There was no statistically significant difference in the incidence of postoperative pulmonary complications between the two groups (p-value >0.05). CONCLUSIONS: The EIT-guided individualized protective ventilation strategy has a lung-protective effect in patients undergoing thoracoscopic partial lung resection. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Purpose Open abdominal surgeries are associated with an increased risk of postoperative pulmonary complications, especially in obese patients, which seem to be related directly to intraoperative mechanical ventilation. The present study aimed to compare the effect of using conventional protective ventilation (CPV) [low tidal volume and fixed positive end expiratory pressure (PEEP)] with open lung approach (OLA) (recruitment maneuver followed by personalized PEEP) on postoperative pulmonary complications. Patients and methods A total of 56 obese patients undergoing open abdominal surgery under general anesthesia were enrolled and randomly assigned to either the CPV group in which they received a tidal volume of 7 ml/kg with fixed PEEP level of 5 cmH2O or the OLA group in which they had alveolar recruitment maneuver followed by individualized PEEP. The primary outcome was the early postoperative pulmonary complications during the first 5 days after surgery. Secondary outcomes included lung mechanics, gas exchange, and hemodynamics during the intraoperative period as well as length of hospital stay, postoperative extrapulmonary complications, and intrahospital mortality. Results Postoperative pulmonary complications in the first 5 days were significantly higher in the CPV than in the OLA group. During the intraoperative period, the static compliance, the PEEP, and plateau pressure were significantly higher in the OLA group than the CPV group. On the contrary, driving pressure was significantly lower in the OLA group. Better oxygenation was observed in the OLA group in the intraoperative period and postoperative days 1 and 3. Pulmonary function tests were significantly better among patients who received the OLA on the first and third postoperative days. Conclusion The OLA may be used as an acceptable alternative to CPV as it was associated with less postoperative pulmonary complications, better intraoperative and postoperative oxygenation, and better postoperative pulmonary functions. [ABSTRACT FROM AUTHOR]

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 oeso­phageal 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 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 H2O. 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 0.05). 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.

With a rapid development of one-lung ventilation ( OLV) technology in children, its applications are gradually gaining popularity in pediatric thoracic surgery. It may prevent cross-infection from another lung and provide better operating space and vision. This review summarized the latest researches of pediatric OL V and intraoperative ventilation. [ABSTRACT FROM AUTHOR]

BackgroundA 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.MethodsThe 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.DiscussionVA-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 RegistrationChiCTR2200067118.

Abstract 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 H2O. The respiratory rate was then re-adjusted within a range from 12 to 40 breaths/min until EtCO2 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

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 cmH2O/L. Optimal PEEP was 12.9 cmH2O (10–16) with ΔPTP of 4.1 cmH2O (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. [ABSTRACT FROM AUTHOR]

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. 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 H2O. 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. 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). 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. [ABSTRACT FROM AUTHOR]

To determine whether end-expiratory lung volume measured with volumetric capnography (EELVCO2) 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. EELVCO2 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 EELVCO2 during and after CP. Baseline EELVCO2 was statistically similar to predicted FRC in both groups. At supine and CP, EELVCO2 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 EELVCO2 unchanged in both groups. PEEP adjustments from 5.6 (1.1) to 10.0 (2.5) cmH2O in the F-group (p = 0.0001) and from 5.6 (0.9) to 10.0 (2.6) cmH2O in T-group (p = 0.0001) were necessary to reach baseline EELVCO2 values. EELVCO2 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 EELVCO2 was similar to baseline PEEP in F-group [5.9 (1.8) cmH2O; p = 0.179] but slightly higher in the T-group [6.5 (2.2) cmH2O; p = 0.006]. Those new PEEP values gave EELVCO2 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 EELVCO2 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. [ABSTRACT FROM AUTHOR]

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 H2O. The respiratory rate was then re-adjusted within a range from 12 to 40 breaths/min until EtCO2 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 PaO2/FiO2 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 H2O 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. [ABSTRACT FROM AUTHOR]

Open in new tab Download slide Open in new tab Download slide 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. [ABSTRACT FROM AUTHOR]

Abstract 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 (ΔPTW) with PPCs. We also tested the association of ΔPTW 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 ΔPTW was not different between groups. The association of ΔPTW 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

Abstract 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 cmH2O, 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.

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 warrants 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.

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.

Abstract 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 PaO2/FiO2 with a significant decrease in PaCO2, Pplat, phase 3 slope of the volumetric capnography, PetCO2, 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 PaO2/FiO2 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 (NCT 02816190) ( https://clinicaltrials.gov/ct2/show/NCT02816190?term=propocap&rank=1 ).

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.)

Abstract 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.

Introduction: A lot of clinical studies have shown that during prolonged surgery protective ventilation strategy, including low tidal volume, PEEP and recruitment maneuvers (RM) can reduce the rate of postoperative pulmonary complications, which are the second most common cause for postoperative mortality. Therefore, it is important to investigate clinical methods for preventing them. The strategy of protective ventilation is easy and safe for the patients and inexpensive for application during prolonged surgery.

Abstract Background During passive mechanical ventilation, the driving pressure of the respiratory system is an important mediator of ventilator-induced lung injury. Monitoring of driving pressure during assisted ventilation, similar to controlled ventilation, could be a tool to identify patients at risk of ventilator-induced lung injury. The aim of this study was to describe driving pressure over time and to identify whether and when high driving pressure occurs in critically ill patients during assisted ventilation. Methods Sixty-two patients fulfilling criteria for assisted ventilation were prospectively studied. Patients were included when the treating physician selected proportional assist ventilation (PAV+), a mode that estimates respiratory system compliance. In these patients, continuous recordings of all ventilator parameters were obtained for up to 72 h. Driving pressure was calculated as tidal volume-to-respiratory system compliance ratio. The distribution of driving pressure and tidal volume values over time was examined, and periods of sustained high driving pressure (≥ 15 cmH2O) and of stable compliance were identified and analyzed. Results The analysis included 3200 h of ventilation, consisting of 8.8 million samples. For most (95%) of the time, driving pressure was

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 (ΔPTW) with PPCs. We also tested the association of ΔPTW 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 ΔPTW was not different between groups. The association of ΔPTW 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 ΔPTW 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). [ABSTRACT FROM AUTHOR]

Background: Limiting tidal volume (VT), 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 CO2 clearance, we conducted a study to determine whether and to what extent replacing heat and moisture exchangers (HME) with heated humidifiers (HH) facilitate safe VT 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 VT to obtain a PaCO2 within 30–35 mmHg (HME1); (2) HH with VT titrated to obtain the same PaCO2 (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] PaO2/FiO2 was 173 [146–213] and median PEEP was 8 cmH2O [5–9]. HH allowed to reduce VT by 120 ml [95% CI: 98–144], VT/kg predicted body weight by 1.8 ml/kg [95% CI: 1.5–2.1], plateau pressure and driving pressure by 3.7 cmH2O [2.9–4.3], without affecting PaCO2, 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 cmH2O 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 VT without modifying PaCO2 nor cerebral perfusion. This permits to provide a wider proportion of brain-injured ARDS patients with less injurious ventilation. [ABSTRACT FROM AUTHOR]