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The Coronavirus 2019 (COVID-19) pandemic has led to an unprecedented strain on the ICU resources. It is not known how the ICU resources employed in treating COVID-19 patients are related to inpatient characteristics, use of organ support or mortality.To investigate how the use of ICU resources relate to use of organ support and mortality in COVID-19 patients.A national register-based cohort study.All Swedish ICUs from March 2020 to November 2021.All patients admitted to Swedish ICUs with a primary diagnosis of COVID-19 reported to the national Swedish Intensive Care Register (SIR).Organ support (mechanical ventilation, noninvasive ventilation, high-flow oxygen therapy, prone positioning, surgical and percutaneous tracheostomy, central venous catheterisation, continuous renal replacement therapy and intermittent haemodialysis), discharge at night, re-admission, transfer and ICU and 30-day mortality.Seven thousand nine hundred and sixty-nine patients had a median age of 63 years, and 70% were men. Median daily census was 167% of habitual census, daily new admissions were 20% of habitual census and the median occupancy was 82%. Census and new admissions were associated with mechanical ventilation, OR 1.37 (95% CI 1.28 to 1.48) and OR 1.44 (95% CI 1.13 to 1.84), respectively, but negatively associated with noninvasive ventilation, OR 0.83 (95% CI 0.77 to 0.89) and OR 0.40 (95% CI 0.30 to 52) and high-flow oxygen therapy, OR 0.72 (95% CI 0.67 to 0.77) and OR 0.77 (95% CI 0.61 to 0.97). Occupancy above 90% of available beds was not associated with mechanical ventilation or noninvasive ventilation, but with high-flow oxygen therapy, OR 1.36 (95% CI 1.21 to 1.53). All measures of pressure on resources were associated with transfer to other hospitals, but none were associated with discharge at night, ICU mortality or 30-day mortality.Pressure on ICU resources was associated with more invasive respiratory support, indicating that during these times, ICU resources were reserved for sicker patients.

Background Fluid overload in ICU patients is associated with increased morbidity and mortality. Although studies report on optimisation of resuscitation fluids given to ICU patients, increasing evidence suggests that maintenance fluids and fluids used to administer drugs are important sources of fluid overload. Objectives We aimed to evaluate the volume of maintenance fluids and electrolytes on overall fluid balance and their relation to mortality in stabilised ICU patients. Design Multicentre retrospective observational study. Setting Six mixed surgical and medical ICUs in Sweden. Patients A total of 241 adult patients who spent at least 7 days in the ICU during 2018. Main outcome measures The primary endpoint was the volume of maintenance, resuscitation and drug diluent fluids administered on days 3 to 7 in the ICU. Secondary endpoints were to compare dispensed amounts of maintenance fluids and electrolytes with predicted requirements. We also investigated the effects of administered fluids and electrolytes on patient outcomes. Results During ICU days 3 to 7, 56.4% of the total fluids given were maintenance fluids, nutritional fluids or both, 25.4% were drug fluids and 18.1% were resuscitation fluids. Patients received fluids 1.29 (95% confidence interval 1.07 to 1.56) times their estimated fluid needs. Despite this, 93% of the cohort was treated with diuretics or renal replacement therapy. Patients were given 2.17 (1.57 to 2.96) times their theoretical sodium needs and 1.22 (0.75 to 1.77) times their potassium needs. The median [IQR] volume of fluid loss during the 5-day study period was 3742 [3156 to 4479] ml day-1, with urine output the main source of fluid loss. Death at 90 days was not associated with fluid or electrolyte balance in this cohort. Conclusion Maintenance and drug fluids far exceeded resuscitative fluids in ICU patients beyond the resuscitative phase. This excess fluid intake, in conjunction with high urinary output and treatment for fluid offload in almost all patients, suggests that a large volume of the maintenance fluids given was unnecessary. Trial registration ClinicalTrials.org NCT03972475.

This is a non-final version of an article published in final form in Lipcsey, Tenhunen, Pischke, Kuitunen, Flaatten, De Geer, Sjölin, Frithiof, Chew, Bendel, Kawati, Larsson, Mollnes, Tønnessen, Rubertsson. Endotoxin removal in septic shock with the Alteco LPS Adsorber was safe but showed no benefit compared to placebo in the double-blind randomized controlled trial - the Asset Study. Shock. 2020;54(2):224-231. Purpose: Lipopolysaccharides (LPS) are presumed to contribute to the inflammatory response in sepsis. We investigated if extracorporeal Alteco LPS Adsorber for LPS removal in early gram-negative septic shock was feasible and safe. Also, effects on endotoxin level, inflammatory response, and organ function were assessed. Methods: A pilot, double-blinded, randomized, Phase IIa, feasibility clinical investigation was undertaken in six Scandinavian intensive care units aiming to allocate 32 septic shock patients with abdominal or urogenital focus on LPS Adsorber therapy or a Sham Adsorber, therapy without active LPS binding. The study treatment was initiated within 12 h of inclusion and given for 6 h daily on first 2 days. LPS was measured in all patients. Results: The investigation was terminated after 527 days with eight patients included in the LPS Adsorber group and seven in the Sham group. Twenty-one adverse effects, judged not to be related to the device, were reported in three patients in the LPS Adsorber group and two in the Sham group. Two patients in the Sham group and no patients in the LPS Adsorber group died within 28 days. Plasma LPS levels were low without groups differences during or after adsorber therapy. The changes in inflammatory markers and organ function were similar in the groups. Conclusions: In a small cohort of patients with presumed gram-negative septic shock, levels of circulating endotoxin were low and no adverse effects within 28 days after LPS adsorber-treatment were observed. No benefit compared with a sham device was seen when using a LPS adsorber in addition to standard care.

Hyperosmolality is common in critically ill patients during body fluid volume reduction. It is unknown whether this is only a result of decreased total body water or an active osmole-producing mechanism similar to that found in aestivating animals, where muscle degradation increases urea levels to preserve water. We hypothesized that fluid volume reduction in critically ill patients contributes to a shift from ionic to organic osmolytes similar to mechanisms of aestivation. We performed a post-hoc analysis on data from a multicenter observational study in adult intensive care unit (ICU) patients in the postresuscitative phase. Fluid, electrolyte, energy and nitrogen intake, fluid loss, estimated glomerular filtration rate (eGFR), and estimated plasma osmolality (eOSM) were registered. Contributions of osmolytes Na+, K+, urea, and glucose to eOSM expressed as proportions of eOSM were calculated. A total of 241 patients were included. eOSM increased (median change 7.4 mOsm/kg [IQR−1.9–18]) during the study. Sodium's and potassium's proportions of eOSM decreased (P ClinicalTrials.org Identifier: NCT03972475.

BACKGROUND Iatrogenic fluid overload is associated with increased mortality in the intensive care unit (ICU). Decisions on fluid therapy may, at times, be based on other factors than physiological endpoints. We hypothesized that because of psychological factors volume of available fluid bags would affect the amount of resuscitation fluid administered to ICU patients. METHODS We performed a prospective intervention cross-over study at 3 Swedish ICUs by replacing the standard resuscitation fluid bag of Ringer's Acetate 1000 mL with 500 mL bags (intervention group) for 5 separate months and then compared it with the standard bag size for 5 months (control group). Primary endpoint was the amount of Ringer's Acetate per patient during ICU stay. Secondary endpoints were differences between the groups in cumulative fluid balance and change in body weight, hemoglobin and creatinine levels, urine output, acute kidney failure (measured as the need for renal replacement therapy, RRT) and 90-day mortality. RESULTS Six hundred and thirty-five ICU patients were included (291 in the intervention group, 344 in the control group). There was no difference in the amount of resuscitation fluid per patient during the ICU stay (2200 mL [1000-4500 median IQR] vs 2245 mL [1000-5630 median IQR]), RRT rate (11 vs 9%), 90-day mortality (11 vs 10%) or total fluid balance between the groups. The daily amount of Ringer's acetate administered per day was lower in the intervention group (1040 (280-2000) vs 1520 (460-3000) mL; P = .03). CONCLUSIONS The amount of resuscitation fluid administered to ICU patients was not affected by the size of the available fluid bags. However, altering fluid bag size could have influenced fluid prescription behavior.

BACKGROUND In a previous study, we found a rebound of arterial carbon dioxide tension (PaCO2 ) after stopping THAM buffer administration. We hypothesized that this was due to reduced pulmonary CO2 elimination during THAM administration. The aim of this study was to investigate this hypothesis in an experimental porcine hypercapnic model. METHODS In seven, initially normoventilated, anesthetized pigs (22-27 kg) minute ventilation was reduced by 66% for 7 h. Two hours after commencing hypoventilation, THAM was infused IV for 3 h in a dose targeting a pH of 7.35 followed by a 2 h observation period. Acid-base status, blood-gas content and exhaled CO2 were measured. RESULTS THAM raised pH (7.07 ± 0.04 to 7.41 ± 0.04, P < 0.05) and lowered PaCO2 (15.2 ± 1.4 to 12.2 ± 1.1 kPa, P < 0.05). After the infusion, pH decreased and PaCO2 increased again. At the end of the observation period, pH and PaCO2 were 7.24 ± 0.03 and 16.6 ± 1.2 kPa, respectively (P < 0.05). Pulmonary CO2 excretion decreased from 109 ± 12 to 74 ± 12 ml/min (P < 0.05) during the THAM infusion but returned at the end of the observation period to 111 ± 15 ml/min (P < 0.05). The estimated reduction of pulmonary CO2 elimination during the infusion was 5800 ml. CONCLUSIONS In this respiratory acidosis model, THAM reduced PaCO2 , but seemed not to increase the total CO2 elimination due to decreased pulmonary CO2 excretion, suggesting only cautious use of THAM in hypercapnic acidosis.

Background Low positive end-expiratory pressure (PEEP) can result in alveolar derecruitment, and high PEEP or high tidal volume (VT) in lung overdistension. We investigated cardiogenic oscillations (COS) in the airway pressure signal to investigate whether these oscillations can assess unfavourable intratidal events. COS induce short instantaneous compliance increases within the pressure-volume curve, and consequently in the compliance-volume curve. We hypothesised that increases in COS-induced compliance reflect non-linear intratidal respiratory system mechanics. Methods In mechanically ventilated anaesthetised pigs with healthy (n=13) or atelectatic (n=12) lungs, pressure-volume relationships and the ECG were acquired at a PEEP of 0, 5, 10, and 15 cm H2O. During inspiration, the peak compliance of successive COS (CCOS) was compared with intratidal respiratory system compliance (CRS) within incremental volume steps up to the full VT of 12 ml kg−1. We analysed whether CCOS variation corresponded with systolic arterial pressure variation. Results CCOS-volume curves showed characteristic intratidal patterns depending on the PEEP level and on atelectasis. Increasing CRS- or CCOS-volume patterns were associated with intratidal derecruitment with low PEEP, and decreasing patterns above 6 ml kg−1 and high PEEP showed overdistension. CCOS was not associated with systolic arterial pressure variations. Conclusions Heartbeat-induced oscillations within the course of the inspiratory pressure-volume curve reflect non-linear intratidal respiratory system mechanics. The analysis of these cardiogenic oscillations can be used to detect intratidal derecruitment and overdistension and, hence, to guide PEEP and VT settings that are optimal for respiratory system mechanics.

The aim of the study was to investigate the frequency and outcome of prolonged intensive care unit (ICU) length of stay (LOS) after abdominal aortic aneurysm (AAA) repair in the endovascular era.All patients operated on for AAA between 1999 and 2013 at Uppsala University hospital were identified. Data were retrieved from the Swedish Vascular registry, the Swedish Intensive Care registry, the National Population registry, and case records. Prolonged ICU LOS was defined as ≥ 48 h during the primary hospital stay. Patients surviving ≥ 48 h after AAA surgery were included in the analysis.A total of 725 patients were identified, of whom 707 (97.5%) survived ≥ 48 h; 563 (79.6%) underwent intact AAA repair and 144 (20.4%) ruptured AAA repair. A total of 548 patients (77.5%) required 48 h of intensive care, 115 (16.3%) 2-6 days and 44 (6.2%) ≥ 7 days. The rate of prolonged ICU LOS declined considerably over time, from 41.4% of all AAA repairs in 1999 to 7.3% in 2013 (p .001) whereas the use of endovascular aortic repair (EVAR) increased from 6.9% in 1999 to 78.0% in 2013 (p .001). The 30 day survival rate was 98.2% for those with48 h ICU stay versus 93.0% for 2-6 days versus 81.8% for ≥ 7 days (p .001); the corresponding 90 day survival was 97.1% versus 86.1% versus 63.6% (p .001) respectively. For patients surviving 90 days after repair, there was no difference in long-term survival between the groups.During the period of progressively increasing use of EVAR, a simultaneous significant reduction in frequency of prolonged ICU LOS occurred. Although prolonged ICU LOS was associated with a high short-term mortality, long-term outcome among those surviving the initial 90 days was less affected.

Spontaneous breathing (SB), when allowed during mechanical ventilation (MV), improves oxygenation in different models of acute lung injury. However, it is not known whether oxygenation is improved during mechanically unsupported SB. Therefore, we compared SB without any support with controlled MV at identical tidal volume (VT) and respiratory rate (RR) without positive end-expiratory pressure in a porcine lung collapse model.In 25 anesthetized piglets, stable lung collapse was induced by application of negative pressure, and animals were randomized to either resume SB or to be kept on MV at identical VT (5 mL/kg; 95% confidence interval: 3.8 to 6.4) and RR (65 per minute [57 to 73]) as had been measured during an initial SB period. Oxygenation was assessed by blood gas analysis (n=15) completed by multiple inert gas elimination technique (n=8 of the 15) for shunt measurement. In addition, possible lung recruitment was studied with computed tomography of the chest (n=10).After induction of lung collapse, PaO2/FIO2 decreased to 90 mm Hg (76 to 103). With SB, PaO2/FIO2 increased to 235 mm Hg (177 to 293) within 15 minutes, whereas MV at identical Vt and RR did not cause any improvement in oxygenation. Intrapulmonary shunt by 45 minutes after induction of lung collapse was lower during SB (SB: 27% [24 to 30] versus MV: 41% [28 to 55]; P=0.017). Neither SB nor MV reduced collapsed lung areas on computed tomography.SB without any support improves oxygenation and reduces shunt in comparison with MV at identical settings. This seems to be achieved without any major signs of recruitment of collapsed lung regions.

Background For mechanical ventilation to be lung-protective, an accepted suggestion is to place the tidal volume (V(T)) between the lower and upper inflection point of the airway pressure-volume relation. The drawback of this approach is, however, that the pressure-volume relation is assessed under quasistatic, no-flow conditions, which the lungs never experience during ventilation. Intratidal nonlinearity must be assessed under real (i.e., dynamic) conditions. With the dynamic gliding-SLICE technique that generates a high-resolution description of intratidal mechanics, the current study analyzed the profile of the compliance of the respiratory system (C(RS)). Methods In 12 anesthetized piglets with lung collapse, the pressure-volume relation was acquired at different levels of positive end-expiratory pressure (PEEP: 0, 5, 10, and 15 cm H(2)O). Lung collapse was assessed by computed tomography and the intratidal course of C(RS) using the gliding-SLICE method. Results Depending on PEEP, C(RS) showed characteristic profiles. With low PEEP, C(RS) increased up to 20% above the compliance at early inspiration, suggesting intratidal recruitment; whereas a profile of decreasing C(RS), signaling overdistension, occurred with V(T) > 5 ml/kg and high PEEP levels. At the highest volume range, C(RS) was up to 60% less than the maximum. With PEEP 10 cm H(2)O, C(RS) was high and did not decrease before 5 ml/kg V(T) was delivered. Conclusions The profile of dynamic C(RS) reflects nonlinear intratidal mechanics of the respiratory system. The SLICE analysis has the potential to detect intratidal recruitment and overdistension. This might help in finding a combination of PEEP and V(T) level that is protective from a lung-mechanics perspective.

If peak inspiratory airway pressure (Ppeak) is used to monitor airway patency, progressive obstruction of the endotracheal tube (ETT) resulting from secretions can go undetected for a prolonged period. The reason is that any increase in Ppeak depends not only on the degree of narrowing but also on the inspiratory flow () rate. Although the impact of narrowing on low inspiratory is small, its decelerating effect on the high expiratory is pronounced and, hence, easily detectable. Dividing the volume-flow curve of a passive expiration into five consecutive segments (slices) and calculating the time constants (tau(Epsilon)) of these slices allows for analyzing whether and how expiratory is impeded by a partial obstruction. In nine piglets, during volume-controlled ventilation, three grades of ETT obstruction were created with an external clamp. In all animals the tau(E) increased with ETT obstruction (mean for the first slice: 550 ms with unobstructed ETT; grade 1: 661; grade 2: 877; and grade 3: 1563 ms, respectively) and this increase was significant with grade 2 and 3 obstruction. Ppeak, by contrast, did not increase significantly (base: 13, grade 1: 14, grade 2: 15 cm H(2)O) until the most severe (grade 3: 20 cm H(2)O) obstruction was created. We conclude that partial obstruction of the ETT can be reliably monitored with the expiratory V signal and has the potential of monitoring ETT narrowing in ventilator-dependent patients independent of the inspiratory pattern applied.

Feeding tubes are used frequently in the intensive care unit to provide enteral nutrition. For critically ill patients, enteral nutrition is preferable to parenteral in terms of cost, complication and gut mucosal maintenance. Fine bore feeding tubes are always preferred because their soft, flexible construction and narrow diameter enables these tubes to be well tolerated by patients and they rarely contribute to sinus infections or obstruction of breathing. On the other hand it is not uncommon that these tubes are misplaced in the tracheobronchial tree or the pleural cavity, especially in high-risk patients, i.e. sedated patients, patients with weak cough reflex, endotracheally intubated patients and agitated patients (1–3). Malpositioning in the peritoneal cavity or the mediastinum through gastric or esophageal perforation is also possible ( 1, 4–7); even intravascular ( 8, 9) and intracranial misplacement have been reported (10–13). The incidence of misplacement of a feeding tube is difficult to estimate because few studies have been performed. The largest study of 1100 such tubes revealed an overall malposition rate of 1.3% ( 1), but it should be mentioned that this study included only radiographically detected misplacements. Other researchers estimate the occurrence of accidental misplacement and migration out of position as high as 13% to 20% in high-risk patients ( 14, 15).

Part of the energy produced by the heartbeat is transferred to the lung and promotes intrapulmonary gas mixing. It is likely that this transmission in the form of local mechanical disturbances affects and reflects respiratory mechanics. The effects of the cardiogenic oscillations were studied in seven piglets during 7 h of monotonous mechanical ventilation. During the 1st h of ventilation, every heartbeat triggered a noticeable transient increase in lung volume of 14 ml (95% confidence interval = 10-17 ml). After 7 h, the increase in lung volume due to heartbeat significantly decreased to 7 ml (95% confidence interval = 2-9 ml, P < 0.05). During the course of ventilation, overall lung compliance and gas exchange were progressively compromised. We conclude that 1) sufficient mechanical energy is transferred from the beating heart to the lung to increase lung volume, and 2) the ability of the heartbeats to help increase lung volume is reduced during long-term ventilation, which reflects the changes in lung compliance.

Background Tracheal pressure (Ptr) is required to measure the resistance of the tracheal tube and the breathing circuit. Ptr can either be measured with a catheter or, alternatively, calculated from the pressure–flow data available from the ventilator. Methods Calculated Ptr was compared with measured Ptr during controlled ventilation and assisted spontaneous breathing in 18 healthy and surfactant-depleted piglets. Their lungs were ventilated using different flow patterns, tidal volumes (VT) and levels of positive end-expiratory pressure. Results In terms of the root mean square error (RMS), indicating the average deviation of calculated from measured Ptr, the difference between calculated and measured Ptr was 0.6 cm H2O (95%CI 0.58–0.65) for volume-controlled ventilation; 0.73 cm H2O (0.72–0.75) for pressure support ventilation; and 0.78 cm H2O (0.75–0.80) for bi-level positive airway pressure ventilation. Conclusion The good agreement between calculated and measured Ptr during varying conditions, suggests that calculating Ptr could help setting the ventilator and choosing the appropriate level of support.

Objective The aim of the study was to investigate the frequency and outcome of prolonged intensive care unit (ICU) length of stay (LOS) after abdominal aortic aneurysm (AAA) repair in the endovascular era. Methods All patients operated on for AAA between 1999 and 2013 at Uppsala University hospital were identified. Data were retrieved from the Swedish Vascular registry, the Swedish Intensive Care registry, the National Population registry, and case records. Prolonged ICU LOS was defined as ≥ 48 h during the primary hospital stay. Patients surviving ≥ 48 h after AAA surgery were included in the analysis. Results A total of 725 patients were identified, of whom 707 (97.5%) survived ≥ 48 h; 563 (79.6%) underwent intact AAA repair and 144 (20.4%) ruptured AAA repair. A total of 548 patients (77.5%) required

Fat embolism to the systemic circulation in polytrauma patients is very common. The fat embolism syndrome (FES), however, is a rare condition. We describe a case of traumatic femur fracture with FES that was presented as acute tonsillar herniation (coning) and brain death postoperatively. We believe that in this case the prone position and moderate hypercapnia contributed to the acute coning.

The beating heart can be interpreted as an inborn natural oscillator generating mechanical energy. With the ventilated lung in close anatomical neighborhood the generated energy is partially transferred from the heart to the lung and further on propagated towards the airway opening inducing so called cardiogenic oscillations (CGO). During mechanical ventilation CGOs can be recognized as small fluctuations superimposed to the respiratory pattern applied by the respirator. We hypothesize that CGOs reflect the mechanical properties of the lung, especially changes in compliance. We analyzed 25 mechanically ventilated piglets during volume controlled ventilation, 13 of them healthy and 12 with pure oxygen produced initial atelectasis, at different PEEP levels (0, 5, 10 and 15 mbar). Compliances of the respiratory system (RS) were determined from CGO (CCGO) using first order polynomial fit and by SLICE method (CSLICE), both based on inspiratory pressure and flow signal. Resulting volume-compliance relationships of each method separately were utilized as supporting points for cubic spline interpolation. The resulting intratidal compliance tracks of both methods were compared to each other.

Only extreme degrees of endotracheal tube (ETT) narrowing can be detected with monitoring of tidal volume (V(T)) during pressure-controlled ventilation (PCV). To assess the degree of ETT obstruction in PCV and to compare it to V(T) monitoring, we produced 3 levels of partial ETT obstruction in 11 healthy anesthetized piglets using ETTs of 4 different inner diameters (IDs 9.0, 8.0, 7.0, and 6.0 mm). An expiratory flow over volume ((e)-V) curve was plotted and the time constant (tau(e)) at 15% of expiration time (T(e)) was calculated. We also calculated the fractional volume expired during the first 15% of T(e) (V(ex fract,15)) and compared those variables to full expiratory V(T) for each of the 3 obstructions. V(T) monitoring failed to detect ETT narrowing. By contrast, V(ex fract,15) decreased and tau(e) increased significantly with increasing ETT narrowing (for IDs 9.0, 8.0, 7.0, and 6.0, mean V(ex fract,15) was 195, 180, 146, and 134 mL respectively and mean tau(e) was 380, 491, 635, 794 ms for IDs 9.0, 8.0, 7.0, and 6.0 respectively). We conclude that when the elastic recoil that drives (e) is appropriately considered, analysis of (e) and V(ex fract,15) detects partial ETT obstruction during PCV.

Heartbeats transfer mechanical energy to the lungs causing flow and pressure disturbances that appear as cardiogenic oscillations (COS) at the airway opening. Here we adopt a new approach for analyzing respiratory system mechanics. We consider the beating heart as a natural intrathoracic mechanical oscillator transferring mechanical energy to the lungs that travels across the lung parenchyma. COS therefore convey information on the mechanical conditions of the lung parenchyma that they cross.