Median PaO2 Research Articles

Pulmonary Events in ICU patients with hyperoxia: is it possible to relate arterial partial pressure of oxygen to coded diseases? A retrospective analysis

ObjectiveOxygen has been used liberally in ICUs for a long time to prevent hypoxia in ICU- patients. Current evidence suggests that paO2 >300 mmHg should be avoided, it remains uncertain whether an “optimal level” exists. We investigated how “mild” hyperoxia influences diseases and in-hospital mortality. DesignThis is a retrospective study. Setting112 mechanically ventilated ICU-patients were enrolled. Patients or participants112 ventilated patients were included and categorized into two groups based on the median paO2 values measured in initial 24 h of mechanical ventilation: normoxia group (paO2 ≤ 100 mmHg, n = 43) and hyperoxia group patients (paO2 > 100 mmHg, n = 69). InterventionsNo interventions were performed. Main variables of interestThe primary outcome was the incidence of pulmonary events, the secondary outcomes included the incidence of other new organ dysfunctions and in-hospital mortality. ResultsThe baseline characteristics, such as age, body mass index, lactate levels, and severity of disease scores, were similar in both groups. There were no statistically significant differences in the incidence of pulmonary events, infections, and new organ dysfunctions between the groups. 27 out of 69 patients (39.1%) in the “mild” hyperoxia group and 12 out of 43 patients (27.9%) in the normoxia group died during their ICU or hospital stay (p = 0.54). The mean APACHE Score was 29.4 (SD 7.9) in the normoxia group and 30.0 (SD 6.7) in the hyperoxia group (p = 0.62). ConclusionsWe found no differences in pulmonary events, other coded diseases, and in-hospital mortality between both groups. It remains still unclear what the "best oxygen regime" is for intensive care patients.

Predictive Hypoxemic Threshold for Tolerating the Apnea Test While Assessing Death by Neurological Criteria

Abstract Background The apnea test (AT) plays a vital role in diagnosing brain death by evaluating the absence of spontaneous respiratory activity. It entails disconnecting the patient from mechanical ventilation to raise the CO2 partial pressure and lower the pH. Occasionally, the AT is aborted because of safety concerns, such as hypoxemia and hemodynamic instability, to prevent worsening conditions. However, the exact oxygen partial pressure level needed before commencing AT, indicating an inability to tolerate the test, is still uncertain. This study seeks to determine pre-AT oxygen levels linked with a heightened risk of test failure. Methods We conducted a retrospective cohort study involving patients suspected of having brain death at the Tel Aviv Medical Center from 2010 to 2022. The primary outcome was defined as an arterial partial O2 pressure (PaO2) level of 60 mmHg or lower at the conclusion of the AT. This threshold is significant because it marks the point at which the saturation curve deflects, potentially leading to rapid deterioration in the patient’s oxygen saturation. Results Among the 70 patients who underwent AT, 7 patients met the primary diagnostic criteria. Patients with a PaO2 ≤ 60 mmHg at the conclusion of the AT exhibited a significantly lower initial median PaO2 of 243.7 mmHg compared with those with higher pre-AT PaO2 levels of 374.8 mmHg (interquartile range 104.65–307.00 and interquartile range 267.8–444.9 respectively, P value = 0.0041). Pre-AT PaO2 levels demonstrated good discriminatory ability for low PaO2 levels according to the receiver operating characteristic (ROC) curve, with an area under the curve of 0.76 (95% confidence interval 0.52–0.99). Conclusions PaO2 values at the conclusion of the AT are closely associated with PaO2 values at the beginning of the test. Establishing a cutoff value of approximately 300 mmHg PaO2 at the onset of AT may assist in avoiding saturation drops below 90%.

Pulmonary Events in ICU patients with hyperoxia: is it possible to relate arterial partial pressure of oxygen to coded diseases? A retrospective analysis

ObjectiveOxygen has been used liberally in ICUs for a long time to prevent hypoxia in ICU- patients. Current evidence suggests that paO2 >300 mmHg should be avoided, it remains uncertain whether an “optimal level” exists. We investigated how “mild” hyperoxia influences diseases and in-hospital mortality. DesignThis is a retrospective study. Setting112 mechanically ventilated ICU-patients were enrolled. Patients or participants112 ventilated patients were included and categorized into two groups based on the median paO2 values measured in initial 24 h of mechanical ventilation: normoxia group (paO2 ≤ 100 mmHg, n = 43) and hyperoxia group patients (paO2 > 100 mmHg, n = 69). InterventionsNo interventions were performed. Main variables of interestThe primary outcome was the incidence of pulmonary events, the secondary outcomes included the incidence of other new organ dysfunctions and in-hospital mortality. ResultsThe baseline characteristics, such as age, body mass index, lactate levels, and severity of disease scores, were similar in both groups. There were no statistically significant differences in the incidence of pulmonary events, infections, and new organ dysfunctions between the groups. 27 out of 69 patients (39.1%) in the “mild” hyperoxia group and 12 out of 43 patients (27.9%) in the normoxia group died during their ICU or hospital stay (p = 0.54). The mean APACHE Score was 29.4 (SD 7.9) in the normoxia group and 30.0 (SD 6.7) in the hyperoxia group (p = 0.62). ConclusionsWe found no differences in pulmonary events, other coded diseases, and in-hospital mortality between both groups. It remains still unclear what the "best oxygen regime" is for intensive care patients.

Exposure to hyperoxemia and mortality in cardiac intensive care unit patients

Abstract Funding Acknowledgements None. Background Hyperoxemia (a high PaO2, i.e. >200-300 mmHg) has been associated with adverse outcomes in general critical care settings as well as in acute cardiovascular care conditions. The association between hyperoxemia and mortality has not been characterized in the heterogeneous population admitted to the cardiac intensive care unit (CICU). We aimed to examine the association between hyperoxemia on CICU admission with in-hospital mortality. Methods We retrospectively analyzed Mayo Clinic CICU patients from January 2007 to April 2018. PaO2 closest on admission was analyzed as a continuous variable (per 100 mmHg) and categorized as: 60-100 mmHg (51.9%), 101-150 mmHg (28.6%), 151-200 mmHg (10.6%), 201-300 mmHg (6.4%), and >300 mmHg (2.5%). Those without PaO2 on admission and those with hypoxemia were excluded. The primary outcome was all-cause in-hospital mortality evaluated using logistic regression, after adjusting for age, Charlson Comorbidity Index, M-CARS, and use of IMV and NIPPV. Results A total of 3,368 patients were included (median 70.3 years, 39.4% women). Admission diagnoses included ACS (37.0%, with 19.8% STEMI), HF (67.8%), shock (33.0%) and cardiac arrest (25.3%). Median admission PaO2 was 99 (IQR 78, 136) mmHg, with no difference in median PaO2 between hospital survivors and inpatient deaths (99 versus 98, p = 0.38). A J-shaped relationship was observed between admission PaO2 and in-hospital mortality (Figure A), with slightly higher mortality below 100 mmHg and incrementally higher mortality above this threshold (esp. at >200 mmHg). The incremental association between higher PaO2 and mortality (adjusted OR 1.17 per 100 mmHg higher, 95% CI 1.01-1.34, P = 0.03) was focused in the highest PaO2 group (i.e., >300 mmHg; Figure B). Conclusion Hyperoxia (esp. PaO2 >300 mmHg) on CICU admission is associated with increased in-hospital mortality, demonstrating a J-shaped association with an inflection point of lowest mortality around 100 mmHg. Further studies are warranted to assess if specific oxygen targets influence outcomes in critically ill cardiac patients.

Pa o2 and Mortality in Neonatal Extracorporeal Membrane Oxygenation: Retrospective Analysis of the Extracorporeal Life Support Organization Registry, 2015-2020.

Extracorporeal life support can lead to rapid reversal of hypoxemia but the benefits and harms of different oxygenation targets in severely ill patients are unclear. Our primary objective was to investigate the association between the Pa o2 after extracorporeal membrane oxygenation (ECMO) initiation and mortality in neonates treated for respiratory failure. Retrospective analysis of the Extracorporeal Life Support Organization (ELSO) Registry data, 2015-2020. Newborns supported by ECMO for respiratory indication were included. None. Pa o2 24 hours after ECMO initiation (H24 Pa o2 ) was reported. The primary outcome was 28-day mortality. We identified 3533 newborns (median age 1 d [interquartile range (IQR), 1-3]; median weight 3.2 kg [IQR, 2.8-3.6]) from 198 ELSO centers, who were placed on ECMO. By 28 days of life, 731 (20.7%) had died. The median H24 Pa o2 was 85 mm Hg (IQR, 60-142). We found that both hypoxia (Pa o2 < 60 mm Hg) and moderate hyperoxia (Pa o2 201-300 mm Hg) were associated with greater adjusted odds ratio (aOR [95% CI]) of 28-day mortality, respectively: aOR 1.44 (95% CI, 1.08-1.93), p = 0.016, and aOR 1.49 (95% CI, 1.01-2.19), p value equals to 0.045. Early hypoxia or moderate hyperoxia after ECMO initiation are each associated with greater odds of 28-day mortality among neonates requiring ECMO for respiratory failure.

Pre-oxygenation with high-flow oxygen through the nasopharyngeal airway compared to facemask on carbon dioxide clearance in emergency adults: a prospective randomized non-blinded clinical trial

IntroductionBefore tracheal intubation, it is essential to provide sufficient oxygen reserve for emergency patients with full stomachs. Recent studies have demonstrated that high-flow nasal oxygen (HFNO) effectively pre-oxygenates and prolongs apneic oxygenation during tracheal intubation. Despite its effectiveness, the use of HFNO remains controversial due to concerns regarding carbon dioxide clearance. The air leakage and unknown upper airway obstruction during HFNO therapy cause reduced oxygen flow above the vocal cords, possibly weaken the carbon dioxide clearance.MethodsPatients requiring emergency surgery who had fasted < 8 h and not drunk < 2 h were randomly assigned to the high-flow group, who received 100% oxygen at 30–60 L/min through nasopharyngeal airway (NPA), or the mask group, who received 100% oxygen at 8 L/min. PaO2 and PaCO2 were measured immediately before pre-oxygenation (T0), anesthesia induction (T1), tracheal intubation (T2), and mechanical ventilation (T3). The gastric antrum’s cross-sectional area (CSA) was measured using ultrasound technology at T0, T1, and T3. Details of complications, including hypoxemia, reflux, nasopharyngeal bleeding, postoperative pulmonary infection, postoperative nausea and vomiting (PONV), and postoperative nasopharyngeal pain, were recorded. The primary outcomes were PaCO2 measured at T1, T2, and T3. The secondary outcomes included PaO2 at T1, T2, and T3, CSA at T1 and T3, and complications happened during this trial.ResultsPre-oxygenation was administered by high-flow oxygen through NPA (n = 58) or facemask (n = 57) to 115 patients. The mean (SD) PaCO2 was 32.3 (6.7) mmHg in the high-flow group and 34.6 (5.2) mmHg in the mask group (P = 0.045) at T1, 45.0 (5.5) mmHg and 49.4 (4.6) mmHg (P < 0.001) at T2, and 47.9 (5.1) mmHg and 52.9 (4.6) mmHg (P < 0.001) at T3, respectively. The median ([IQR] [range]) PaO2 in the high-flow and mask groups was 404.5 (329.1–458.1 [159.8–552.9]) mmHg and 358.9 (274.0–413.3 [129.0–539.1]) mmHg (P = 0.007) at T1, 343.0 (251.6–428.7 [73.9–522.1]) mmHg and 258.3 (162.5–347.5 [56.0–481.0]) mmHg (P < 0.001) at T2, and 333.5 (229.9–411.4 [60.5–492.4]) mmHg and 149.8 (87.0–246.6 [51.2–447.5]) mmHg (P < 0.001) at T3, respectively. The CSA in the high-flow and mask groups was 371.9 (287.4–557.9 [129.0–991.2]) mm2 and 386.8 (292.0–537.3 [88.3–1651.7]) mm2 at T1 (P = 0.920) and 452.6 (343.7–618.4 [161.6–988.1]) mm2 and 385.6 (306.3–562.0 [105.5–922.9]) mm2 at T3 (P = 0.173), respectively. The number (proportion) of complications in the high-flow and mask groups is shown below: hypoxemia: 1 (1.7%) vs. 9 (15.8%, P = 0.019); reflux: 0 (0%) vs. 0 (0%); nasopharyngeal bleeding: 1 (1.7%) vs. 0 (0%, P = 1.000); pulmonary infection: 4 (6.9%) vs. 3 (5.3%, P = 1.000); PONV: 4 (6.9%) vs. 4 (7.0%, P = 1.000), and nasopharyngeal pain: 0 (0%) vs. 0 (0%).ConclusionsCompared to facemasks, pre-oxygenation with high-flow oxygen through NPA offers improved carbon dioxide clearance and enhanced oxygenation prior to tracheal intubation in patients undergoing emergency surgery, while the risk of gastric inflation had not been ruled out.Trial registrationThis trial was registered prospectively at the Chinese Clinical Research Registry on 26/4/2022 (Registration number: ChiCTR2200059192).

Prehospital Advanced Airway Management and Ventilation for Out-of-Hospital Cardiac Arrest with Prehospital Return of Spontaneous Circulation: A Prospective Observational Cohort Study in Japan

Background The relationship among advanced airway management (AAM), ventilation, and oxygenation in patients with out-of-hospital cardiac arrest (OHCA) who achieve prehospital return of spontaneous circulation (ROSC) has not been validated. This study was designed to evaluate ventilation and oxygenation for each AAM technique (supraglottic devices [SGA] or endotracheal intubation [ETI]) using arterial blood gas (ABG) results immediately after hospital arrival. Methods This observational cohort study, using data from the Japanese Association for Acute Medicine OHCA Registry, included patients with OHCA with prehospital and hospital arrival ROSC between July 1, 2014, and December 31, 2019. The primary outcomes were the partial pressure of carbon dioxide in the arterial blood (PaCO2) and partial pressure of oxygen in the arterial blood (PaO2) in the initial ABG at the hospital for each AAM technique (SGA or ETI) performed by paramedics. The secondary outcome was favorable neurological outcome (cerebral performance category [CPC] 1 or 2) for specific PaCO2 levels, which were defined as good ventilation (PaCO2 ≤45 mmHg) and insufficient ventilation (PaCO2 >45 mmHg). Results This study included 1,527 patients. Regarding AAM, 1,114 and 413 patients were ventilated using SGA and ETI, respectively. The median PaCO2 and PaO2 levels were 74.50 mmHg and 151.35 mmHg in the SGA group, while 66.30 mmHg and 173.50 mmHg in the ETI group. PaCO2 was significantly lower in the ETI group than in the SGA group (12.55 mmHg; 95% CI 15.27 to 8.20, P-value < 0.001), while no significant difference was found in PaO2 by multivariate linear regression analysis. After stabilizing inverse probability of weighting (IPW), the adjusted odds ratio for favorable neurological outcome at 1 month was significant in the good ventilation group compared to the insufficient ventilation cohort (adjusted odds ratio = 2.12, 95%CI: 1.40 to 3.19, P value < 0.001). Conclusion The study showed that in OHCA patients with prehospital ROSC, the PaCO2 levels in the initial ABG were lower in the group with AAM by ETI than in the SGA group. Furthermore, patients with prehospital ROSC and PaCO2 ≤45 mmHg on arrival had an increased odds of favorable neurological outcome after stabilized IPW adjustment.

The effects of mechanical versus bag-valve ventilation on gas exchange during cardiopulmonary resuscitation in emergency department patients: A randomized controlled trial (CPR-VENT)

IntroductionEffective ventilation is crucial for successful cardiopulmonary resuscitation (CPR). Previous studies indicate that higher arterial oxygen levels (PaO2) during CPR increase the chances of successful resuscitation. However, the advantages of mechanical ventilators over bag-valve ventilation for achieving optimal PaO2 during CPR remain uncertain. MethodWe conducted a randomized trial involving non-traumatic adult cardiac arrest patients who received CPR in the ED. After intubation, patients were randomly assigned to ventilate with a mechanical ventilator (MV) or bag valve ventilation (BV). In MV group, ventilation settings were: breath rate 10/minute, tidal volume 6–7 ml/kg, inspiratory time 1 second, positive end-expiratory pressure 0 cm water, inspiratory oxygen fraction (FiO2) 100%. The primary outcome was to compare the difference in PaO2 from arterial blood gases (ABG) obtained 4–10 minutes later during CPR between both groups. ResultsSixty patients were randomized (30 in each group). The study population consisted of: 57% male, median age 62 years, 37% received bystander CPR, and 20% had an initial shockable rhythm. Median time from arrest to intubation was 24 minutes. The median PaO2 was not significantly different in the BV compared to MV [36.5 mmHg (14.0–70.0) vs. 29.0 mmHg (15.0–70.0), P = 0.879]. Other ABG parameters and rates of return of spontaneous circulation and survival were not different. ConclusionsIn ED patients with refractory cardiac arrest, arterial oxygen levels during CPR were comparable between patients ventilated with MV and BV. Mechanical ventilation is at least feasible and safe during CPR in intubated cardiac arrest patients.

EXPLORING THE ROLE OF CENTRAL VENOUS OXYGEN SATURATION IN THE EVALUATION AND MANAGEMENT OF SEVERE HYPOXEMIA IN MECHANICALLY VENTILATED PATIENTS.

Background: Although central venous oxygen saturation (ScvO 2 ) has been used as an endpoint for the treatment of circulatory shock, its role in guiding the evaluation and treatment of patients with severe hypoxemia remains to be assessed. The aim of this study was to assess the incidence of low ScvO 2 in a cohort of hypoxemic patients and the association of this finding with differences in clinical management and patient outcomes. Methods: Retrospective review of data from adult intensive care unit patients with hypoxemia who required invasive mechanical ventilation for over 24 h and had at least one ScvO 2 measured within 6 h of a PaO 2 /FiO 2 ratio <200. Results: Of 442 mechanically ventilated patients with severe hypoxemia, 249 (56%) had an ScvO 2 <70%. When compared with patients with ScvO 2 ≥70%, those with low ScvO 2 had worse systemic oxygenation and hemodynamic parameters and were more likely to receive red blood cell transfusions (31.7% vs. 18.1%, P = 0.001), epinephrine (27.3% vs. 16.6%, P = 0.007), and inodilators. Outcomes such as median intensive care unit length of stay (7.5 vs. 8.3 days, P = 0.337) and hospital mortality (39.8% vs. 35.7%, P = 0.389) were not different between groups. When stratified by the central venous-to-arterial CO 2 difference (∆PCO 2 ), patients with a low ScvO 2 and normal ∆PCO 2 had lower median PaO 2 and hemoglobin levels and received more red blood cell transfusions, whereas those with an increased ∆PCO 2 had a lower pulse pressure and cardiac index and were more likely to receive epinephrine and milrinone. Conclusion: Low ScvO 2 is frequently observed in mechanically ventilated patients with severe hypoxemia, and these patients receive different interventions. Clinicians often use therapies targeting systemic oxygen delivery to correct low ScvO 2 . Prospective research is needed to identify patients with severe hypoxemia that might benefit from interventions targeting systemic oxygen delivery.

Use of bi-caval cannulae for veno-venous ECMO in neonates and children

PurposeVeno-arterial ECMO remains the most common mode of extracorporeal support in infants and children, and despite increases in overall ECMO numbers the utilisation of veno-venous ECMO in neonates appears to be decreasing. We report here outcomes of neonatal and paediatric patients managed with veno-venous ECMO via bi-caval cannulae over a 10-year period in a tertiary referral ICU.MethodsRetrospective single-centre case series of veno-venous ECMO cases using dual lumen cannulae over a 10-year period at a tertiary referral paediatric hospital with a low volume ECMO program.ResultsIn the 10-year period 2013–2022, 33 patients required ECMO with 23 receiving veno-arterial ECMO and 10 managed with veno-venous cannulation - 8 with bi-caval cannulae and 2 with multi-site cannulation. Overall survival was 23/33 (69.6%) and in the veno-venous group survival was 7/10 (70%). Median oxygenation index prior to veno-venous cannulation in the 8 patients undergoing bi-caval cannulation was 48 (range 34–54) and median PaO2 was 42 mmHg (range 34–59 mmHg). Duration of ECMO ranged from 7 to 14 days (median 9 days). Complications included migration of the cannula into the hepatic vein, minor and major bleeding, and compromised blood flow secondary to pneumomediastinum.ConclusionsVeno-venous ECMO can be reliably established via a single bi-caval cannula in the majority of patients. Outcomes in this small series from a low volume centre are broadly comparable to those reported from the ELSO database.

Association of Conventional Ultrafiltration on Postoperative Pulmonary Complications

BackgroundPostoperative pulmonary complications increase mortality after cardiac surgery. Conventional ultrafiltration may reduce pulmonary complications by removing mediators of bypass-induced inflammation and countering hemodilution. We tested the primary hypothesis that conventional ultrafiltration reduces postoperative pulmonary complications, and secondarily, improves early pulmonary function assessed by the ratio of PaO2 to fractional inspired oxygen concentration. MethodsThis retrospective analysis compared the incidence of postoperative pulmonary complications in adult patients who underwent cardiac surgery, with and without the use of conventional ultrafiltration, by using logistic regression with adjustment for confounding variables. The primary outcome was a composite of reintubation, prolonged ventilation, pneumonia, or pleural effusion. Secondarily, we examined early postoperative lung function using a quantile regression model. We also explored whether red blood cell transfusion differed between groups. ResultsOf 8026 patients, 1043 (13%) received conventional ultrafiltration. After adjustment for confounding variables, the incidence of the composite primary outcome was higher in the conventional ultrafiltration group (12.1% vs 9.9%; P = .03), with an estimated odds ratio of 1.25 (95% CI, 1.02-1.53; P = .03). The median (quantiles) PaO2–to–fractional inspired oxygen concentration ratio was 373 (303-433) vs 368 (303-428), with the estimated adjusted difference in medians of 5 (95% CI, −5.9 to 16; P = .37). The estimated odds ratio of intraoperative transfusion was 1.38 (95% CI, 1.19-1.60; P < .0001) and for postoperative transfusion was 1.30 (95% CI, 1.14-1.49; P = .0001). ConclusionsUse of conventional ultrafiltration was not associated with a reduction in the composite of postoperative pulmonary complications or improved early pulmonary function. We found no evidence of benefit from use of conventional ultrafiltration during cardiac surgery.

Supraglottic airway devices are associated with asphyxial physiology after prolonged CPR in patients with refractory Out-of-Hospital cardiac arrest presenting for extracorporeal cardiopulmonary resuscitation

BackgroundMultiple randomized clinical trials have compared specific airway management strategies during ACLS with conflicting results. However, patients with refractory cardiac arrest died in almost all cases without the availability of extracorporeal cardiopulmonary resuscitation (ECPR). Our aim was to determine if endotracheal intubation (ETI) was associated with improved outcomes compared to supraglottic airways (SGA) in patients with refractory cardiac arrest presenting for ECPR. MethodsWe retrospectively studied 420 consecutive adult patients with refractory out-of-hospital cardiac arrest due to shockable presenting rhythms presenting to the University of Minnesota ECPR program. We compared outcomes between patients receiving ETI (n = 179) and SGA (n = 204). The primary outcome was the pre-cannulation arterial PaO2 upon arrival to the ECMO cannulation center. Secondary outcomes included neurologically favorable survival to hospital discharge and eligibility for VA-ECMO based upon resuscitation continuation criteria applied upon arrival to the ECMO cannulation center. ResultsPatients receiving ETI had significantly higher median PaO2 (71 vs. 58 mmHg, p = 0.001), lower median PaCO2 (55 vs. 75 mmHg, p < 0.001), and higher median pH (7.03 vs. 6.93, p < 0.001) compared to those receiving SGA. Patients receiving ETI were also significantly more likely to meet VA-ECMO eligibility criteria (85% vs. 74%, p = 0.008). Of patients eligible for VA-ECMO, patients receiving ETI had significantly higher neurologically favorable survival compared to SGA (42% vs. 29%, p = 0.02). ConclusionsETI was associated with improved oxygenation and ventilation after prolonged CPR. This resulted in increased rate of candidacy for ECPR and increased neurologically favorable survival to discharge with ETI compared to SGA.

Influenza Season and Outcome After Elective Cardiac Surgery: An Observational Cohort Study

BackgroundAn asymptomatic respiratory viral infection during cardiac surgery could lead to pulmonary complications and increased mortality. For elective surgery, testing for respiratory viral infection before surgery or vaccination could reduce the number of these pulmonary complications. The aim of this study was to investigate the association between influenzalike illness (ILI) seasons and prolonged mechanical ventilation and inhospital mortality in a Dutch cohort of adult elective cardiac surgery patients. MethodsCardiac surgery patients who were admitted to the intensive care unit between January 1, 2014, and February 1, 2020, were included. The primary endpoint was the duration of invasive mechanical ventilation in the ILI season compared with baseline season. Secondary endpoints were the median Pao2 to fraction of inspired oxygen ratio on days 1, 3, and 7 and postoperative inhospital mortality. ResultsA total of 42,277 patients underwent cardiac surgery, 12,994 (30.7%) in the ILI season, 15,843 (37.5%) in the intermediate season, and 13,440 (31.8%) in the baseline season. No hazard rates indicative of a longer duration of invasive mechanical ventilation during the ILI season were found. No differences were found for the median Pao2 to fraction of inspired oxygen ratio between seasons. However, inhospital mortality was higher in the ILI season compared with baseline season (odds ratio 1.67; 95% CI, 1.14-2.46). ConclusionsPatients undergoing cardiac surgery during the ILI season were at increased risk of inhospital mortality compared with patients in the baseline season. No evidence was found that this difference is caused by direct postoperative pulmonary complications.

Acute Improvements of Oxygenation with Cpap and Clinical Outcomes in Severe COVID-19 Pneumonia: A Multicenter, Retrospective Study.

It is not known if the degrees of improvement in oxygenation obtained by CPAP can predict clinical outcomes in patients with COVID-19 pneumonia. This was a retrospective study conducted on patients with severe COVID-19 pneumonia treated with CPAP in three University hospitals in Milan, Italy, from March 2020 to March 2021. Arterial gas analysis was obtained before and 1 h after starting CPAP. CPAP failure included either death in the respiratory units while on CPAP or the need for intubation. Two hundred and eleven patients (mean age 64 years, 74% males) were included. Baseline median PaO2, PaO2/FiO2 ratio (P/F), and the alveolar-arterial (A-a) O2 gradient were 68 (57−83) mmHg, 129 (91−179) mmHg and 310 (177−559) mmHg, respectively. Forty-two (19.9%) patients died in the respiratory units and 51 (24.2%) were intubated. After starting CPAP, PaO2/FiO2 increased by 57 (12−113; p < 0.001) mmHg, and (A-a) O2 was reduced by 68 (−25−250; p < 0.001) mmHg. A substantial overlap of PaO2, P/F, and A-a gradient at baseline and during CPAP was observed in CPAP failures and successes; CPAP-associated improvements in oxygenation in both groups were similar. In conclusion, CPAP-associated improvements in oxygenation do not predict clinical outcomes in patients with severe COVID-19 pneumonia.

ARTERIAL HYPEROXIA AND MORTALITY IN PATIENTS UNDERGOING VENOARTERIAL EXTRACORPOREAL MEMBRANE OXYGENATION.

Background: Venoarterial extracorporeal membrane oxygenation (VA-ECMO) can easily lead to supranormal oxygenation. The impact of hyperoxygenation beyond the early VA-ECMO support phase is unexplored. We sought to investigate its association with short- and long-term mortality. Methods: A total of 10,615 arterial blood gases of 179 patients undergoing VA-ECMO between 2013 and 2018 in our cardiosurgical tertiary center were analyzed for partial pressure of oxygen (PaO2) and its association with in-hospital, 90-day, and 1-year mortality. Patients were stratified into terciles (T) based on PaO2. Results: The median systemic PaO2 during VA-ECMO was 122 mm Hg (Q1-Q3, 111-158 mm Hg) and was significantly higher in 90-day nonsurvivors versus survivors (134 mm Hg [Q1-Q3, 114-175 mm Hg] vs. 114 mm Hg [Q1-Q3, 109-136 mm Hg]; P < 0.001). The incidence of mortality increased at all time points tested after VA-ECMO implantation along with the increasing terciles of PaO2. The lowest mortality rates were noted for patients with median PaO2 values of <115 mm Hg (T1), whereas patients with median PaO2 values of >144 mm Hg (T3) had the highest mortality rates. Bonferroni multiple testing analysis found the T3 of PaO2 to be a predictor of decreased 90-day survival in comparison with T1 (P < 0.001) and T2 (P = 0.002). Multivariable Cox regression analyses for in-hospital, 90-day, and 1-year mortality showed a significant association of the T3 compared with the T2 and the T1 of PaO2 to mortality across all endpoints. Conclusion: Hyperoxygenation during VA-ECMO might be associated with increased all-cause mortality. The results of our study further document the known toxicity of hyperoxygenation in general critical care patients and mark the need to focus specifically on VA-ECMO patients.

High arterial oxygen levels and supplemental oxygen administration in traumatic brain injury: insights from CENTER-TBI and OzENTER-TBI

PurposeThe effect of high arterial oxygen levels and supplemental oxygen administration on outcomes in traumatic brain injury (TBI) is debated, and data from large cohorts of TBI patients are limited. We investigated whether exposure to high blood oxygen levels and high oxygen supplementation is independently associated with outcomes in TBI patients admitted to the intensive care unit (ICU) and undergoing mechanical ventilation.MethodsThis is a secondary analysis of two multicenter, prospective, observational, cohort studies performed in Europe and Australia. In TBI patients admitted to ICU, we describe the arterial partial pressure of oxygen (PaO2) and the oxygen inspired fraction (FiO2). We explored the association between high PaO2 and FiO2 levels within the first week with clinical outcomes. Furthermore, in the CENTER-TBI cohort, we investigate whether PaO2 and FiO2 levels may have differential relationships with outcome in the presence of varying levels of brain injury severity (as quantified by levels of glial fibrillary acidic protein (GFAP) in blood samples obtained within 24 h of injury).ResultsThe analysis included 1084 patients (11,577 measurements) in the CENTER-TBI cohort, of whom 55% had an unfavorable outcome, and 26% died at a 6-month follow-up. Median PaO2 ranged from 93 to 166 mmHg. Exposure to higher PaO2 and FiO2 in the first seven days after ICU admission was independently associated with a higher mortality rate. A trend of a higher mortality rate was partially confirmed in the OzENTER-TBI cohort (n = 159). GFAP was independently associated with mortality and functional neurologic outcome at follow-up, but it did not modulate the outcome impact of high PaO2 and FiO2 levels, which remained independently associated with 6-month mortality.ConclusionsIn two large prospective multicenter cohorts of critically ill patients with TBI, levels of PaO2 and FiO2 varied widely across centers during the first seven days after ICU admission. Exposure to high arterial blood oxygen or high supplemental oxygen was independently associated with 6-month mortality in the CENTER-TBI cohort, and the severity of brain injury did not modulate this relationship. Due to the limited sample size, the findings were not wholly validated in the external OzENTER-TBI cohort. We cannot exclude the possibility that the worse outcomes associated with higher PaO2 were due to use of higher FiO2 in patients with more severe injury or physiological compromise. Further, these findings may not apply to patients in whom FiO2 and PaO2 are titrated to brain tissue oxygen monitoring (PbtO2) levels. However, at minimum, these findings support the need for caution with oxygen therapy in TBI, particularly since titration of supplemental oxygen is immediately applicable at the bedside.

Adaptive Support Ventilation and Lung-Protective Ventilation in ARDS.

Adaptive support ventilation (ASV) is a partially closed-loop ventilation mode that adjusts tidal volume (VT) and breathing frequency (f) to minimize mechanical work and driving pressure. ASV is routinely used but has not been widely studied in ARDS. The study was a crossover study with randomization to intervention comparing a pressure-regulated, volume-targeted ventilation mode (adaptive pressure ventilation [APV], standard of care at Beth Israel Deaconess Medical Center) set to VT 6 mL/kg in comparison with ASV mode where VT adjustment is automated. Subjects received standard of care (APV) or ASV and then crossed over to the alternate mode, maintaining consistent minute ventilation with 1-2 h in each mode. The primary outcome was VT corrected for ideal body weight (IBW) before and after crossover. Secondary outcomes included driving pressure, mechanics, gas exchange, mechanical power, and other parameters measured after crossover and longitudinally. Twenty subjects with ARDS were consented, with 17 randomized and completing the study (median PaO2 /FIO2 146.6 [128.3-204.8] mm Hg) and were mostly passive without spontaneous breathing. ASV mode produced marginally larger VT corrected for IBW (6.3 [5.9-7.0] mL/kg IBW vs 6.04 [6.0-6.1] mL/kg IBW, P = .035). Frequency was lower with patients in ASV mode (25 [22-26] breaths/min vs 27 [22-30)] breaths/min, P = .01). In ASV, lower respiratory-system compliance correlated with smaller delivered VT/IBW (R2 = 0.4936, P = .002). Plateau (24.7 [22.6-27.6] cm H2O vs 25.3 [23.5-26.8] cm H2O, P = .14) and driving pressures (12.8 [9.0-15.8] cm H2O vs 11.7 [10.7-15.1] cm H2O, P = .29) were comparable between conventional ventilation and ASV. No adverse events were noted in either ASV or conventional group related to mode of ventilation. ASV targeted similar settings as standard of care consistent with lung-protective ventilation strategies in mostly passive subjects with ARDS. ASV delivered VT based upon respiratory mechanics, with lower VT and mechanical power in subjects with stiffer lungs.

Prognostic Value of Mid-Region Proadrenomedullin and In Vitro Interferon Gamma Production for In-Hospital Mortality in Patients with COVID-19 Pneumonia and Respiratory Failure: An Observational Prospective Study.

Coagulopathy and immune dysregulation have been identified as important causes of adverse outcomes in coronavirus disease (COVID-19). Mid-region proadrenomedullin (MR-proADM) is associated with endothelial damage and has recently been proposed as a prognostic factor in COVID-19. In non-COVID-19 immunocompromised patients, low in vitro interferon gamma (IFNγ) production correlates with infection risk and mortality. This prospective, monocentric, observational study included adult patients consecutively admitted with radiologic evidence of COVID-19 pneumonia and respiratory failure. MR-proADM and in vitro IFNγ production were measured at T0 (day 1 from admission) and T1 (day 7 from enrollment). One hundred patients were enrolled. Thirty-six percent were females, median age 65 (Q1–Q3 54.5–75) years, and 58% had ≥1 comorbidity. Only 16 patients had received COVID-19 vaccination before hospitalization. At admission, the median PaO2:FiO2 ratio was 241 (157–309) mmHg. In-hospital mortality was 13%. MR-proADM levels differed significantly between deceased and survivors both at T0 (1.41 (1.12–1.77) nmol/L vs. 0.79 (0.63–1.03) nmol/L, p < 0.001) and T1 (1.67 (1.08–1.96) nmol/L vs. 0.66 (0.53–0.95) nmol/L, p < 0.001). In vitro IFNγ production at T0 and T1 did not vary between groups. When only the subset of non-vaccinated patients was considered, both biomarkers at T1 resulted significantly associated with in-hospital mortality. AUROC for MR-proADM at T0 to predict in-hospital mortality was 0.87 (95%CI 0.79–0.94), with the best cut-off point at 1.04 nmol/L (92% sensitivity, 75% specificity and 98% negative predictive value). In patients with COVID-19 pneumonia and different degrees of respiratory failure, MR-proADM at admission and during hospitalization resulted strongly associated with in-hospital mortality. Low in vitro IFNγ production after the first week of hospitalization was associated with mortality in non-vaccinated patients possibly identifying the subgroup characterized by a higher degree of immune suppression.

Prediction of survival in infants with congenital diaphragmatic hernia and the response to inhaled nitric oxide

The use of inhaled nitric oxide (iNO) in treating pulmonary hypertension in infants with congenital diaphragmatic hernia (CDH) is controversial. Our aims were to identify factors associated with survival in CDH infants and whether this was influenced by the response to iNO. Results of CDH infants treated in a tertiary surgical and medical perinatal centre in a ten year period (2011–2021) were reviewed. Factors affecting survival were determined. To assess the response to iNO, blood gases prior to and 30 to 60 min after initiation of iNO were analysed and PaO2/FiO2 ratios and oxygenation indices (OI) calculated. One hundred and five infants were admitted with CDH; 46 (43.8%) infants died. The CDH infants who died had a lower median observed to expected lung to head ratio (O/E LHR) (p < 0.001) and a higher median highest OI on day 1 (HOId1) (p < 0.001). HOId1 predicted survival after adjusting for gestational age, Apgar score at 5 min and O/E LHR (odds ratio 0.948 (95% confidence intervals 0.913–0.983)). Seventy-two infants (68.6%) received iNO; 28 survived to discharge. The median PaO2 (46.7 versus 58.8 mmHg, p < 0.001) and the median PaO2/FiO2 ratio (49.4 versus 58.8, p = 0.003) improved post iNO initiation. The percentage change in the PaO2/FiO2 ratio post iNO initiation was higher in infants who survived (69.4%) compared to infants who died (10.2%), p = 0.018.Conclusion: The highest OI on day 1 predicted survival. iNO improved oxygenation in certain CDH infants and a positive response was more likely in those who survived.What is Known:• The use of iNO is controversial in infants with CDH with respect to whether it improves survival.What is New:• We have examined predictors of survival in CDH infants including the response to iNO and demonstrated that the highest oxygenation index on day 1 predicted survival (AUCROC =0.908).• Certain infants with CDH responded to iNO and those with a greater response were more likely to survive.

Mechanical ventilation in patients with cardiogenic shock complicating acute myocardial infarction

Abstract Funding Acknowledgements Type of funding sources: None. Introduction Invasive mechanical ventilation (IMV) provides up to a 30% reduction in cardiac output requirements and is frequently used in patients with cardiogenic shock following acute myocardial infarction (AMICS). However, practice of IMV in the setting of AMICS is sparsely described. Purpose The aim was to evaluate the use of IMV in a contemporary cohort of patients with AMICS. Methods Between 2010 and 2017, all adult AMICS patients admitted to two tertiary heart centres, providing AMICS care for two thirds of the Danish population, were individually identified through patient records. Temporal changes in application of IMV were registered as well as patient characteristics. Real-time electronic ICU data were available for a subset of mechanically ventilated ICU patients (n=566), and were retrieved for the first 24 hours of IMV, following ICU admission, and described in relation to 30-day survival and the presence of out-of-hospital cardiac arrest (OHCA). Results A total of 1716 AMICS patients were retrospectively identified, of which 1274 (74%) received IMV during ICU admission (IMV-ICU). The proportion of IMV increased from 70% in 2010 to 78% in 2017. IMV-ICU patients were younger (67 vs 76 years), more frequently male (79% vs 61%), and more likely to have OHCA (54% vs 3%) and higher lactate at diagnosis of cardiogenic shock (5.8 vs 4.1 mmol/L) compared with non-intubated patients (p for all&amp;lt;0.001). Among IMV-ICU patients, 69% were intubated in the prehospital setting, of which three quarters presented with OHCA. Median PaO2 and PCO2 were both within normal ranges among 30-day survivors and non-survivors. However, non-survivors required 10-25% higher median fraction of inspired oxygen (p&amp;lt;0.001; FiO2), positive-end-expiratory pressure (p=0.002; PEEP), and minute ventilation (p&amp;lt;0.001; MV). Differences in IMV settings were mainly driven by non-survivors without OHCA (see table). Conclusion In a contemporary cohort of patients with AMICS, use of IMV increased during the observation period from 2010 to 2017. Observations did not reveal any association between 30-day mortality and IMV parameters in OHCA-patients, whereas FiO2, PEEP, and MV were significantly elevated in 30-day non-survivors without OHCA.