Effect of Extended Prone Positioning in Intubated COVID-19 Patients with Acute Respiratory Distress Syndrome: A Systematic Review and Meta-Analysis.

INPLASY REGISTRATION NUMBER: INPLASY202390072.

Ketamine-based Sedation Use in Mechanically Ventilated Critically Ill Patients with COVID-19: A Multicenter Cohort Study.

Backgrounds: Ketamine possesses analgesia, anti-inflammation, anticonvulsant, and neuroprotection properties. However, the evidence that supports its use in mechanically ventilated critically ill patients with COVID-19 is insufficient. The study's goal was to assess ketamine's effectiveness and safety in critically ill, mechanically ventilated (MV) patients with COVID-19. Methods: Adult critically ill patients with COVID-19 were included in a multicenter retrospective-prospective cohort study. Patients admitted between March 1, 2020, and July 31, 2021, to five ICUs in Saudi Arabia were included. Eligible patients who required MV within 24 hours of ICU admission were divided into two sub-cohort groups based on their use of ketamine (Control vs. Ketamine). The primary outcome was the length of stay (LOS) in the hospital. P/F ratio differences, lactic acid normalization, MV duration, and mortality were considered secondary outcomes. Propensity score (PS) matching was used (1:2 ratio) based on the selected criteria. Results: In total, 1,130 patients met the eligibility criteria. Among these, 1036 patients (91.7 %) were in the control group, whereas 94 patients (8.3 %) received ketamine. The total number of patients after PS matching, was 264 patients, including 88 patients (33.3 %) who received ketamine. The ketamine group's LOS was significantly lower (beta coefficient (95 % CI): -0.26 (-0.45, -0.07), P = 0.008). Furthermore, the PaO2/FiO2 ratio significantly improved 24 hours after the start of ketamine treatment compared to the pre-treatment period (6 hours) (124.9 (92.1, 184.5) vs. 106 (73.1, 129.3; P = 0.002). Additionally, the ketamine group had a substantially shorter mean time for lactic acid normalization (beta coefficient (95 % CI): -1.55 (-2.42, -0.69), P 0.01). However, there were no significant differences in the duration of MV or mortality. Conclusions: Ketamine-based sedation was associated with lower hospital LOS and faster lactic acid normalization but no mortality benefits in critically ill patients with COVID-19. Thus, larger prospective studies are recommended to assess the safety and effectiveness of ketamine as a sedative in critically ill adult patients.

Parasternal intercostal thickening at hospital admission: a promising indicator for mechanical ventilation risk in subjects with severe COVID-19.

We aimed to evaluate the ability of parasternal intercostal thickening fraction (PIC TF) to predict the need for mechanical ventilation, and survival in subjects with severe Coronavirus disease-2019 (COVID-19). This prospective observational study included adult subjects with severe COVID-19. The following data were collected within 12 h of admission: PIC TF, respiratory rate oxygenation index, [Formula: see text] ratio, chest CT, and acute physiology and chronic health evaluation II score. The ability of PIC TF to predict the need for ventilatory support (primary outcome) and a composite of invasive mechanical ventilation and/or 30-days mortality were performed using the area under the receiver operating characteristic (AUC) analysis. Multivariate analysis was done to identify the independent predictors for the outcomes. Fifty subjects were available for the final evaluation. The AUC (95% confidence interval [CI]) for the right and left PIC TF ability to predict the need for ventilator support was 0.94 (0.83-0.99), 0.94 (0.84-0.99), respectively, with a cut off value of > 8.3% and positive predictive value of 90-100%. The AUC for the right and left PIC TF to predict invasive mechanical ventilation and/or 30 days mortality was 0.95 (0.85-0.99) and 0.90 (0.78-0.97), respectively. In the multivariate analysis, only the PIC TF was found to independently predict invasive mechanical ventilation and/or 30-days mortality. In subjects with severe COVID-19, PIC TF of 8.3% can predict the need to ventilatory support with a positive predictive value of 90-100%. PIC TF is an independent risk factor for the need for invasive mechanical ventilation and/or 30-days mortality.

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.

Evaluation of the Daily Change in PaO2/FiO2 Ratio as a Predictor of Abnormal Chest X-rays in Intensive Care Unit Patients Post Mechanical Ventilation Weaning: A Retrospective Cohort Study.

Background and Objectives: The routine daily chest X-ray (CXR) strategy is no longer recommended in intensive care unit (ICU) patients. However, it is difficult for intensivists to collectively accept the on-demand CXR strategy because of the ambiguous clinical criteria for conducting CXRs. This study evaluated the predictive value of the change in PaO2/FiO2 (PF ratio) for abnormal CXR findings in ICU patients after mechanical ventilation (MV). Materials and Methods: A retrospective cohort study was conducted between January 2016 and March 2021 on ICU patients with MV who had at least 48 h of MV, and stayed at least 72 h in the ICU post-MV. Routine daily CXRs and daily changes in the PF ratios were investigated during the three days post-MV. Results: The 186 patients included in the study had a median age of 77 years (interquartile range: 65-82), and 116 (62.4%) were men. One hundred and eight (58.1%) patients had abnormal CXR findings, defined as one or more abnormal CXRs among the daily CXRs during the three days post-extubation. The reintubation rate was higher in the abnormal CXR group (p = 0.01). Of the 558 CXRs (normal = 418, abnormal = 140) and PF ratios, the daily change in PF ratio had a significant predictive accuracy for abnormal CXR findings (AUROC = 0.741, p < 0.01). Conclusions: The change in PF ratio (the Youden index point: ≤-23) had a sensitivity of 65.7%, and a specificity of 79.9%. Based on these results, the daily change in the PF ratio could be utilized as a predictive indicator of abnormal CXRs in ICU patients after MV treatment.

Prediction of Noninvasive Ventilation Failure in a Mixed Population Visiting the Emergency Department in a Tertiary Care Center in India.

Background: Noninvasive ventilation (NIV) is an established first-line treatment of acute respiratory failure both in emergency departments (ED) and intensive care unit (ICU) settings. It is however not always successful. Materials and methods: Prospective, observational study was done among patients above 18 years presenting with acute respiratory failure initiated on NIV. Patients were placed in one of two groups covering successful NIV treatment and NIV failure. Two groups were compared on four variables: initial respiratory rate (RR), initial high-sensitivity C-reactive protein (hs-CRP), PaO2/FiO2 ratio (p/f ratio), and heart rate, acidosis, consciousness, oxygenation, and respiratory rate (HACOR) score at the end of 1 hour of initiation of NIV. Results: A total of 104 patients fulfilling the inclusion criteria were included in the study, of which 55 (52.88%) were exclusively treated with NIV (NIV success group), and 49 (47.11%) required endotracheal intubation and mechanical ventilation (NIV failure group). Noninvasive ventilation failure group had a higher mean initial RR compared with NIV success group (40.65 ± 3.88 vs 31.98 ± 3.15, p <0.001). Mean initial PaO2/FiO2 ratio was also significantly lower in the NIV failure group (184.57 ± 50.33 vs 277.29 ± 34.70, p <0.001). Odds ratio for successful NIV treatment with a high initial RR was 0.503 (95% confidence interval (CI), 0.390-0.649) and with a higher initial PaO2/FiO2 ratio was 1.053 (95% CI: 1.032-1.071 and with a HACOR score of >5 at the end of 1 hour of initiation of NIV was highly associated with NIV failure (p <0.001). A high initial level of hs-CRP was 0.949 (95% CI: 0.927-0.970). Conclusion: Noninvasive ventilation failure could be predicted with information available at presentation in ED, and unnecessary delay in endotracheal intubation could possibly be prevented. How to cite this article: Mathen PG, Kumar KPG, Mohan N, Sreekrishnan TP, Nair SB, Krishnan AK, et al. Prediction of Noninvasive Ventilation Failure in a Mixed Population Visiting the Emergency Department in a Tertiary Care Center in India. Indian J Crit Care Med 2022;26(10):1115-1119.

Baseline characteristics of COVID-19 Italian patients admitted to Desio Hospital, Lombardy: a retrospective study.

The correlation of clinical, radiological and laboratory findings of patients at admission in the Emergency Department (ED) with clinical severity and risk of mortality was investigated. Adult coronavirus disease 2019 (COVID-19) patients hospitalized in March 2020 in Desio Hospital, Lombardy, were retrospectively included in the study, and categorized in terms of disease severity and adverse outcome. Out of the 175 patients enrolled, 79% presented one or more comorbidities, with cardiovascular disease being the most frequent (62%). More than half of the patients showed lymphocytopenia and 20% thrombocytopenia. The patients in the severe group presented higher absolute neutrophil count (ANC), C-reactive protein (CRP), AST, LDH, procalcitonin (PCT) and BUN values compared to the non-severe group (p < .05). Increased odds of mortality associated with older age (OR = 22.43; 95% CI 5.22-96.27), partial pressure of oxygen (PaO2)/fraction of inspired oxygen (FIO2) ratio < 200 (OR = 4.97; 95% CI 1.55-15.84), clinical severity (OR = 21.32; 95% CI 2.27-200.13), creatinine > 106.08 µmol/L (OR = 2.87; 95% CI 1.04-7.92) and creatine kinase > 2.90 µkat/L (OR = 3.80; 95% CI 1.31-10.9) were observed on admission (p < .05). The above findings may contribute to identify early risk factors of poor prognosis, and to select the most appropriate management for patients.

Correlation of Oxygen Index, Oxygen Saturation Index, and PaO2/FiO2 Ratio in Invasive Mechanically Ventilated Adults.

BACKGROUND: With the oxygen saturation index (OSI) being a noninvasive surrogate for oxygen index (OI) and P/F ratio, examining the correlation between PaO2/FiO2 (P/F ratio), OI, and OSI in mechanically ventilated adults will benefit in those settings where arterial blood gas monitoring is not readily accessible. MATERIALS AND METHODS: Data were collected for patients ≥18 years who were under invasive (endotracheal intubation) mechanical ventilation at medical or surgical wards in a tertiary care hospital. RESULTS: After natural log transformation, the correlations between P/F ratio and OI (r = -0.94) and OI and OSI (r = 0.82) were strong, but weaker between P/F ratio and OSI (r = -0.69). CONCLUSION: Future bigger studies are needed to evaluate whether monitoring OSI and/or OI over P/F ratio will impact treatment outcomes. HOW TO CITE THIS ARTICLE: Vadi S. Correlation of Oxygen Index, Oxygen Saturation Index, and PaO2/FiO2 Ratio in Invasive Mechanically Ventilated Adults. Indian J Crit Care Med 2021;25(1):54-55.

Helmet NIV in Acute Hypoxemic Respiratory Failure due to COVID-19: Change in PaO2/FiO2 Ratio a Predictor of Success.

In acute respiratory failure due to severe coronavirus disease 2019 (COVID-19) pneumonia, mechanical ventilation remains challenging and may result in high mortality. The use of noninvasive ventilation (NIV) may delay required invasive ventilation, increase adverse outcomes, and have a potential aerosol risk to caregivers. Data of 30 patients were collected from patient files and analyzed. Twenty-one (70%) patients were weaned successfully after helmet-NIV support (NIV success group), and invasive mechanical ventilation was required in 9 (30%) patients (NIV failure group) of which 8 (26.7%) patients died. In NIV success vs failure patients, the mean baseline PaO2/FiO2 ratio (PFR) (147.2 ± 57.9 vs 156.8 ± 59.0 mm Hg; p = 0.683) and PFR before initiation of helmet (132.3 ± 46.9 vs 121.6 ± 32.7 mm Hg; p = 0.541) were comparable. The NIV success group demonstrated a progressive improvement in PFR in comparison with the failure group at 2 hours (158.8 ± 56.1 vs 118.7 ± 40.7 mm Hg; p = 0.063) and 24 hours (PFR-24) (204.4 ± 94.3 vs 121.3 ± 32.6; p = 0.016). As predictor variables, PFR-24 and change (delta) in PFR at 24 hours from baseline or helmet initiation (dPFR-24) were significantly associated with NIV success in univariate analysis but similar significance could not be reflected in multivariate analysis perhaps due to a small sample size of the study. The PFR-24 cutoff of 161 mm Hg and dPFR-24 cutoff of -1.44 mm Hg discriminate NIV success and failure groups with the area under curve (confidence interval) of 0.78 (0.62-0.95); p = 0.015 and 0.74 (0.55-0.93); p = 0.039, respectively. Helmet interface NIV may be a safe and effective tool for the management of patients with severe COVID-19 pneumonia with acute respiratory failure. More studies are needed to further evaluate the role of helmet NIV especially in patients with initial PFR <150 mm Hg to define PFR/dPFR cutoff at the earliest time point for prediction of helmet-NIV success. How to cite this article Jha OK, Kumar S, Mehra S, Sircar M, Gupta R. Helmet NIV in Acute Hypoxemic Respiratory Failure due to COVID-19: Change in PaO2/FiO2 Ratio a Predictor of Success. Indian J Crit Care Med 2021;25(10):1137-1146.

Association between SpO2/FiO2 Ratio and PaO2/FiO2 Ratio in Different Modes of Oxygen Supplementation.

BACKGROUND: Acute hypoxemic respiratory failure (AHRF) is a major factor for increased mortality in the intensive care unit (ICU). We hypothesized that the noninvasive index SpO2/FiO2 (SF) ratio can be used as a surrogate to invasive index PaO2/FiO2 (PF) as SF ratio correlates with PF ratio in all modes of oxygen supplementation. PATIENTS AND METHODS: Patients with acute respiratory failure admitted to the intensive care unit were enrolled in this retrospective cross-sectional study. Fraction of inspired oxygen (FiO2), method of oxygen supplementation, and partial pressure of arterial oxygen (PaO2) were noted from the ABG reports in the medical records. The corresponding SpO2 was noted from the nurse's chart. The calculated SF and PF ratios were recorded, and correlation between the same was noted in different methods of oxygen administration. RESULTS: A total of 300-sample data were collected. Pearson's correlation was used to quantify the relationship between the variables. The study showed a positive correlation, r = 0.66 (p <0.001), between PF ratio and SF ratio. SF threshold values were 285 and 323 for corresponding PF values of 200 and 300 with a sensitivity and specificity in the range of 70 to 80%. In addition, SF and PF could also be used interchangeably irrespective of the mode of oxygen supplementation, as the median values of PF ratio (p = 0.06) and SF ratio (p = 0.88) were not statistically significant. CONCLUSION: In patients with AHRF, the noninvasive SF ratio can be used as a surrogate to invasive index PF in all modes of oxygen supplementation. HOW TO CITE THIS ARTICLE: Babu S, Abhilash KPP, Kandasamy S, Gowri M. Association between SpO2/FiO2 Ratio and PaO2/FiO2 Ratio in Different Modes of Oxygen Supplementation. Indian J Crit Care Med 2021;25(9):1001-1005.

A novel concept for evaluation of pulmonary function utilizing PaO2/FiO2 difference at the distinctive FiO2 in cellular ex vivo lung perfusion-an experimental study.

For more accurate lung evaluation in ex vivo lung perfusion (EVLP), we have devised a new parameter, PaO2 /FiO2 ratio difference (PFD); PFD1-0.4  = P/F ratio at FiO2 1.0 - P/F ratio at FiO2 0.4. The aim of this study is to compare PFD and transplant suitability, and physiological parameters utilized in cellular EVLP. Thirty-nine human donor lungs were perfused. At 2 h of EVLP, PFD1-0.4 was compared with transplant suitability and physiological parameters. In a second study, 10 pig lungs were perfused in same fashion. PFD1-0.4 was calculated by blood from upper and lower lobe pulmonary veins and compared with lobe wet/dry ratio and pathological findings. In human model, receiver operating characteristic curve analysis showed PFD1-0.4 had the highest area under curve, 0.90, sensitivity, 0.96, to detect nonsuitable lungs, and significant negative correlation with lung weight ratio (R2  = 0.26, P < 0.001). In pig model, PFD1-0.4 on lower and upper lobe pulmonary veins were significantly associated with corresponding lobe wet/dry ratios (R2  = 0.51, P = 0.019; R2  = 0.37, P = 0.060), respectively. PFD1-0.4 in EVLP demonstrated a significant correlation with lung weight ratio and allowed more precise assessment of individual lobes in detecting lung edema. Moreover, it might support decision-making in evaluation with current EVLP criteria.

The predictive value of PaO2/FIO2 and additional parameters for in-hospital mortality in patients with acute pulmonary embolism: an 8-year prospective observational single-center cohort study.

BACKGROUND: Rapid stratification and appropriate treatment on admission are critical to saving lives of patients with acute pulmonary embolism (PE). None of the clinical prediction tools perform well when applied to all patients with acute PE. It may be important to integrate respiratory features into the 2014 European Society of Cardiology model. First, we aimed to assess the relationship between the arterial partial pressure of oxygen/fraction of inspired oxygen (PaO2/FIO2) ratio and in-hospital mortality, determine the optimal cutoff value of PaO2/FIO2, and determine if this value, which is quick and easy to obtain on admission, is a predictor of in-hospital mortality in this population. Second, we aimed to evaluate the potential additional determinants including laboratory parameters that may affect the in-hospital mortality. We hypothesized that the PaO2/FiO2 ratio would be a clinical prediction tool for in-hospital mortality in patients with acute PE. METHODS: A prospective single-center observational cohort study was conducted in Beijing Hospital from January 2010 to November 2017. Arterial blood gas analysis data captured on admission, clinical characteristics, risk factors, laboratory data, imaging findings, and in-hospital mortality were compared between survivors and non-survivors. The area under the receiver operating characteristic curve (AUC) for in-hospital mortality based on the PaO2/FiO2 value was determined, and the association between the parameters and in-hospital mortality was analyzed by using logistic regression analysis. RESULTS: Body mass index, history of cancer, PaO2/FiO2 value, pulse rate, cardiac troponin I level, lactate dehydrogenase level, white blood cell count, D-dimer level, and risk stratification measurements differed between survivors and non-survivors. The optimal cutoff value of PaO2/FiO2 for predicting mortality was 265 (AUC = 0.765, P < 0.001). Only a PaO2/FiO2 ratio < 265 (95% confidence interval [CI] 1.823-21.483, P = 0.004), history of cancer (95% CI 1.161-15.927, P = 0.029), and risk stratification (95% CI 1.047-16.957, P = 0.043) continued to be associated with an increased risk of in-hospital mortality of acute PE. CONCLUSION: A simple determination of the PaO2/FiO2 ratio at <265 may provide important information on admission about patients' in-hospital prognosis, and PaO2/FiO2 ratio < 265, history of cancer, and risk stratification are predictors of in-hospital mortality of acute PE.

Hypoxia preconditioning attenuates lung injury after thoracoscopic lobectomy in patients with lung cancer: a prospective randomized controlled trial.

BACKGROUND: Hypoxic preconditioning (HPC) may protect multiple organs from various injuries. We hypothesized that HPC would reduce lung injury in patients undergoing thoracoscopic lobectomy. METHODS: In a prospective randomized controlled trial, 70 patients undergoing elective thoracoscopic lobectomy were randomly allocated to the HPC group or the control group. Three cycles of 5-min hypoxia and 3-min ventilation applied to the nondependent lung served as the HPC intervention. The primary outcome was the PaO2/FiO2 ratio. Secondary outcomes included postoperative pulmonary complications, pulmonary function, and duration of hospital stay. RESULTS: HPC significantly increased the PaO2/FiO2 ratio compared with the control at 30 min after one-lung ventilation and 7 days after operation. Compared with the control, it also significantly improved postoperative pulmonary function and markedly reduced the postoperative hospital stay duration. No significant differences between groups were observed in the incidence of pulmonary complications or overall postoperative morbidity. CONCLUSIONS: HPC improves postoperative oxygenation, enhances the recovery of pulmonary function, and reduces the duration of hospital stay in patients undergoing thoracoscopic lobectomy. TRIAL REGISTRATION: This study was registered in the Chinese Clinical Trial Registry (ChiCTR-IPR-17011249) on April 27, 2017.

ICU mortality is increased with high admission serum osmolarity in all patients other than those admitted with pulmonary diseases and hypoxia.

BACKGROUND AND OBJECTIVE: High serum osmolarity has been shown to be lung protective. There is lack of clinical studies evaluating the impact on outcomes such as mortality. We aimed to examine the effect of serum osmolarity on intensive care unit (ICU) mortality in critically ill patients METHODS: Data from January 2000 to December 2012 was accessed using the Australian and New Zealand Intensive Care Society (ANZICS) Clinical Outcomes and Resource Evaluation (CORE) database. A total of 509 180 patients were included. Serum osmolarity was calculated from data during the first 24 h of ICU admission. Predefined subgroups (Acute Physiology and Chronic Health Evaluation (APACHE) III diagnostic codes), including patients with acute pulmonary diagnoses, were examined. The effect of serum osmolarity on ICU mortality was assessed with analysis adjusted for illness severity (serum sodium, glucose and urea component removed) and year of admission. Results are presented as OR (95% CI) referenced against a serum osmolarity of 290-295 mmol/L. RESULTS: The ICU mortality was elevated at each extremes of serum osmolarity (U-shaped relationship). A similar relationship was found in various subgroups, with the exception of patients with pulmonary diagnoses in whom ICU mortality was not influenced by high serum osmolarity and was different from other non-pulmonary subgroups (P < 0.01). Any adverse associations with high serum osmolarity in pulmonary patients were confined to patients with a PaO2 /FiO2 ratio > 200. CONCLUSION: High admission serum osmolarity was not associated with increased odds for ICU death in pulmonary patients, unlike other subgroup of patients, and could be a potential area for future interventional therapy.

Early pulmonary compliance increase during cardiac surgery predicted post-operative lung dysfunction.

INTRODUCTION: Lung dysfunction following cardiac surgery is currently viewed as the consequence of atelectasis and lung injury. While the mechanism of atelectasis has been largely detailed, the pathogenesis of lung injury after cardiopulmonary bypass is still unclear. Based upon clinical and experimental studies, we hypothesized that lungs could be injured through a mechanical phenomenon. METHODS: We recorded pulmonary compliance at six key moments of a heart operation in 62 adult patients undergoing elective cardiac surgery. We focused on the period lasting from anesthetic induction to aorta unclamping. We calculated the variation of static and dynamic pulmonary compliance caused by thorax opening; ΔCstat1 and ΔCdyn1 and that caused by cardiopulmonary bypass, ΔCstat2 and ΔCdyn2. Blood gases were performed under standardized ventilation after anesthetic induction and after surgical closure. The PaO2/FiO2 ratio was calculated. ∆PaO2/FiO2 was the criterion for lung dysfunction. We compared ΔCstat1 and ΔCdyn1 with both ∆PaO2/FiO2 and, respectively, ΔCstat2 and ΔCdyn2. RESULTS: Static and dynamic compliance increased with the opening of the thorax and decreased with the start of cardiopulmonary bypass. The PaO2/FiO2 ratio diminished after surgery. ΔCstat1 and ΔCdyn1 were negatively correlated with both ∆PaO2/FiO2 (r=-0.42; p<0.001 and r=-0.44; p<0.001) and, respectively, with ΔCstat2 and ΔCdyn2 (r=-0.59; p<0.001 and r=-0.53; p<0.001). CONCLUSIONS: Increased pulmonary compliance induced by the opening of the thorax is correlated with worsened intrapulmonary shunt after cardiopulmonary bypass. A mechanical phenomenon could be partly responsible for post-operative hypoxemia.

Comparison of intraoperative volume and pressure-controlled ventilation modes in patients who undergo open heart surgery.

Respiratory problems occur more frequently in patients who undergo open heart surgery. Intraoperative and postoperative ventilation strategies can prevent these complications and reduce mortality. We hypothesized that PCV would have better effects on gas exchange, lung mechanics and hemodynamics compared to VCV in CABG surgery. Our primary outcome was to compare the PaO2/FiO2 ratio. Patients were randomized into two groups, (VCV, PCV) consisting of 30 individuals each. Two patients were excluded from the study. I/E ratio was adjusted to 1:2 and, RR:10/min fresh air gas flow was set at 3L/min in all patients. In the VCV group TV was set at 8 mL/kg of the predicted body weight. In the PCV group, peak inspiratory pressure was adjusted to the same tidal volume with the VCV group. PaO2/FiO2 was found to be higher with PCV at the end of the surgery. Time to extubation and ICU length of stay was shorter with PCV. Ppeak was similar in both groups. Pplateau was lower and Pmean was higher at the and of the surgery with PCV compared to VCV. The hemodynamic effects of both ventilation modes were found to be similar. PVC may be preferable to VCV in patients who undergo open heart surgery. However, it would be convenient if our findings are supported by similar studies.

Prediction of inspired oxygen fraction for targeted arterial oxygen tension following open heart surgery in non-smoking and smoking patients.

Simple and accurate expressions describing the PaO2-FiO2 relationship in mechanically ventilated patients are lacking. The current study aims to validate a novel mathematical expression for accurate prediction of the fraction of inspired oxygen that will result in a targeted arterial oxygen tension in non-smoking and smoking patients receiving mechanical ventilation following open heart surgeries. One hundred PaO2-FiO2 data pairs were obtained from 25 non-smoking patients mechanically ventilated following open heart surgeries. One data pair was collected at each of FiO2 of 40, 60, 80, and 100% while maintaining same mechanical ventilation support settings. Similarly, another 100 hundred PaO2-FiO2 data pairs were obtained from 25 smoking patients mechanically ventilated following open heart surgeries. The utility of the new mathematical expression in accurately describing the PaO2-FiO2 relationship in these patients was assessed by the regression and Bland-Altman analyses. Significant correlations were seen between the true and estimated FiO2 values in non-smoking (r2 = 0.9424; p < 0.05) and smoking (r2 = 0.9466; p < 0.05) patients. Tight biases between the true and estimated FiO2 values for non-smoking (3.1%) and smoking (4.1%) patients were observed. Also, significant correlations were seen between the true and estimated PaO2/FiO2 ratios in non-smoking (r2 = 0.9530; p < 0.05) and smoking (r2 = 0.9675; p < 0.05) patients. Tight biases between the true and estimated PaO2/FiO2 ratios for non-smoking (-18 mmHg) and smoking (-16 mmHg) patients were also observed. The new mathematical expression for the description of the PaO2-FiO2 relationship is valid and accurate in non-smoking and smoking patients who are receiving mechanical ventilation for post cardiac surgery.

Mechanical ventilation strategies for intensive care unit patients without acute lung injury or acute respiratory distress syndrome: a systematic review and network meta-analysis.

BACKGROUND: It has been shown that the application of a lung-protective mechanical ventilation strategy can improve the prognosis of patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). However, the optimal mechanical ventilation strategy for intensive care unit (ICU) patients without ALI or ARDS is uncertain. Therefore, we performed a network meta-analysis to identify the optimal mechanical ventilation strategy for these patients. METHODS: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library, EMBASE, MEDLINE, CINAHL, and Web of Science for studies published up to July 2015 in which pulmonary compliance or the partial pressure of arterial oxygen/fraction of inspired oxygen (PaO2/FIO2) ratio was assessed in ICU patients without ALI or ARDS, who received mechanical ventilation via different strategies. The data for study characteristics, methods, and outcomes were extracted. We assessed the studies for eligibility, extracted the data, pooled the data, and used a Bayesian fixed-effects model to combine direct comparisons with indirect evidence. RESULTS: Seventeen randomized controlled trials including a total of 575 patients who received one of six ventilation strategies were included for network meta-analysis. Among ICU patients without ALI or ARDS, strategy C (lower tidal volume (VT) + higher positive end-expiratory pressure (PEEP)) resulted in the highest PaO2/FIO2 ratio; strategy B (higher VT + lower PEEP) was associated with the highest pulmonary compliance; strategy A (lower VT + lower PEEP) was associated with a shorter length of ICU stay; and strategy D (lower VT + zero end-expiratory pressure (ZEEP)) was associated with the lowest PaO2/FiO2 ratio and pulmonary compliance. CONCLUSIONS: For ICU patients without ALI or ARDS, strategy C (lower VT + higher PEEP) was associated with the highest PaO2/FiO2 ratio. Strategy B (higher VT + lower PEEP) was superior to the other strategies in improving pulmonary compliance. Strategy A (lower VT + lower PEEP) was associated with a shorter length of ICU stay, whereas strategy D (lower VT + ZEEP) was associated with the lowest PaO2/FiO2 ratio and pulmonary compliance.

Predictors of survival in critically ill patients with acute respiratory distress syndrome (ARDS): an observational study.

BACKGROUND: Currently there is no ARDS definition or classification system that allows optimal prediction of mortality in ARDS patients. This study aimed to examine the predictive values of the AECC and Berlin definitions, as well as clinical and respiratory parameters obtained at onset of ARDS and in the course of the first seven consecutive days. METHODS: The observational study was conducted at a 14-bed intensive care unit specialized on treatment of ARDS. Predictive validity of the AECC and Berlin definitions as well as PaO2/FiO2 and FiO2/PaO2*Pmean (oxygenation index) on mortality of ARDS patients was assessed and statistically compared. RESULTS: Four hundred forty two critically-ill patients admitted for ARDS were analysed. Multivariate Cox regression indicated that the oxygenation index was the most accurate parameter for mortality prediction. The third day after ARDS criteria were met at our hospital was found to represent the best compromise between earliness and accuracy of prognosis of mortality regarding the time of assessment. An oxygenation index of 15 or greater was associated with higher mortality, longer length of stay in ICU and hospital and longer duration of mechanical ventilation. In addition, non-survivors had a significantly longer length of stay and duration of mechanical ventilation in referring hospitals before admitted to the national reference centre than survivors. CONCLUSIONS: The oxygenation index is suggested to be the most suitable parameter to predict mortality in ARDS, preferably assessed on day 3 after admission to a specialized centre. Patients might benefit when transferred to specialized ICU centres as soon as possible for further treatment.