Author Response: Oxygenation Indices in Adult COVID ARDS Patients.

How to cite this article: Vadi SMR, Sanwalka N, Suthar D. Author Response: Oxygenation Indices in Adult COVID ARDS Patients. Indian J Crit Care Med 2024;28(9):889.

Utility of the oxygenation index in management of congenital diaphragmatic hernia: a report from a Thai University Surgical Centre.

BACKGROUND: Oxygenation index (OI) is associated with severity of newborn pulmonary hypertension (PH) in congenital diaphragmatic hernia (CDH). Higher OI may indicate worst degree(s) of PH. OBJECTIVES: This study reports OI dynamic(s) over the first 72 h of life and its correlation with (1) perioperative morbidity and (2) CDH mortality. METHODS: Medical records of inborn CDH babies during 2002-2022 were examined. OI on Days (s) 1-3 and perioperative OI trends were recorded. Operation (primary vs patch repair) and survival rates (%) were studied. RESULTS: Fifty-five CDH newborns (54.5% male: 45.5% female)-mean birth GA 37.5 ± 2.7 wks. had a mean birth weight 2813 ± 684 g with prenatal diagnosis in 32.7% cases. 52/55 (94.5%) were intubated at birth and HFOV deployed in 29 (55.8%). Those requiring HFOV had higher OI on DOL1 (24.8 ± 17 vs 10.3 ± 11.5; p < 0.05), DOL 2 (26.3 ± 22.9 vs 6.7 ± 12.1; p < 0.05) and DOL 3 (21.9 ± 33.8 vs 5.5 ± 9.3; p = 0.04). Operation was undertaken in 36/55 (65.5%). Preoperative mortality group had significant higher OI on DOL 2 (42.1 ± 21.0 vs 14.9 ± 9.3; p = 0.04). CDH defects were-Type A N = 27 (75%), Type B N = 7 (19.4%) and Type C N = 2 (5.6%). Overall mortality was 40% (22/55). Statistically significant OI trends were recorded in non-survival vs. survival groups on DOL 1 (31.6 ± 16.8. vs 10.5 ± 9.0; p < 0.05, DOL 2 (38.1 ± 21.9 vs 6.3 ± 7.1; p < 0.05), and DOL 3 (38.8 ± 39.4; p = 0.012). CONCLUSIONS: OI dynamics are highly predictive for accurate monitoring of CDH cardiorespiratory physiology and crucially may guide ventilatory management as well as timing of surgery.

Revisiting ARDS Classification: Are We There Yet?

How to cite this article: Mishra S. Revisiting ARDS Classification: Are We There Yet? Indian J Crit Care Med 2024;28(10):899-900.

Oxygenation Index, Oxygen Saturation Index vs PaO2/FiO2 *PEEP: A Secondary Analysis of OXIVA-CARDS Study.

Background: The classification of Berlin definition is based on the PaO2/FiO2 ratio, which has been found to have a poor association with mortality. Airway pressures reflect lung compliance and the settings of mechanical ventilators. In this study, we aimed to investigate the change in the severity of COVID-19-associated acute respiratory distress syndrome (ARDS) classification using [PaO2/FiO2 × PEEP] (P/FP) ratio compared to the traditional P/F ratio, and whether the P/FP ratio improves the predictive validity of in-hospital mortality. Methods: Our study sample included patients from the OXIVA-CARDS study. In this secondary analysis, we examined the oxygenation index and oxygen saturation index in relation to the P/FP ratio, as well as the risk of P/FP in mortality. We used Pearson's correlation to assess the relationships between various parameters. Receiver operating characteristic analysis with Youden's index was used to compare the prognostic value of the oxygenation index (OI), oxygen saturation index (OSI), P/F ratio, P/FP ratio, and SaO2/FiO2 ratio for predicting overall mortality. Multiple logistic regression was also performed to determine the impact of mean airway pressure (Pmean), S/F ratio, OI, and P/FP ratio on mortality. Results: A total of 201 patients (with 1543 measurements) were included in the analysis. Overall, 522 (34%) were reclassified into either more or less severe categories. Patients who were classified as having severe ARDS based on the P/FP ratio had significantly lower P/FP ratio, oxygenation index, and A-a O2 gradient as compared to those classified as having severe ARDS based on the P/F ratio (p < 0.05) at all levels of ARDS severity. On multivariate regression analysis, only the OI significantly impacted mortality (p < 0.05). Conclusion: We observed that the oxygen index and oxygen saturation index were more sensitive than the PaO2/FiO2 ratio and P/FP ratio. Additionally, only the oxygenation index had a significant impact on mortality. By including airway pressures in the calculation of the OI, its predictive ability is enhanced compared to using the S/F ratio, P/F ratio, or P/FP ratio. Highlights: The sensitivity of mortality by including Pmean is higher as compared to when only PEEP is taken into consideration. P/FP is a weak predictor of mortality as compared to OI and OSI. How to cite this article: Vadi SMR, Sanwalka N, Suthar D. Oxygenation Index, Oxygen Saturation Index vs PaO2/FiO2 *PEEP: A Secondary Analysis of OXIVA-CARDS Study. Indian J Crit Care Med 2024;28(10):917-922.

Differential impacts of body composition on oxygen kinetics and exercise tolerance of HFrEF and HFpEF patients.

This study aims to (1) compare the kinetics of pulmonary oxygen uptake (VO2p), skeletal muscle deoxygenation ([HHb]), and microvascular O2 delivery (QO2mv) between heart failure (HF) patients with reduced ejection fraction (HFrEF) and those with preserved ejection fraction (HFpEF), and (2) explore the correlation between body composition, kinetic parameters, and exercise performance. Twenty-one patients (10 HFpEF and 11 HFrEF) underwent cardiopulmonary exercise testing to assess VO2 kinetics, with near-infrared spectroscopy (NIRS) employed to measure [HHb]. Microvascular O2 delivery (QO2mv) was calculated using the Fick principle. Dual-energy X-ray absorptiometry (DEXA) was performed to evaluate body composition. HFrEF patients exhibited significantly slower VO2 kinetics (time constant [t]: 63 ± 10.8 s vs. 45.4 ± 7.9 s; P < 0.05) and quicker [HHb] response (t: 12.4 ± 9.9 s vs. 25 ± 11.6 s; P < 0.05). Microvascular O2 delivery (QO2mv) was higher in HFrEF patients (3.6 ± 1.2 vs. 1.7 ± 0.8; P < 0.05), who also experienced shorter time to exercise intolerance (281.6 ± 84 s vs. 405.3 ± 96 s; P < 0.05). Correlation analyses revealed a significant negative relationship between time to exercise and both QO2mv (ρ= -0.51; P < 0.05) and VO2 kinetics (ρ= -0.63). Body adiposity was negatively correlated with [HHb] amplitude (ρ= -0.78) and peak VO2 (ρ= -0.54), while a positive correlation was observed between lean muscle percentage, [HHb] amplitude, and tau (ρ= 0.74 and 0.57; P < 0.05), respectively. HFrEF patients demonstrate more severely impaired VO2p kinetics, skeletal muscle deoxygenation, and microvascular O2 delivery compared to HFpEF patients, indicating compromised peripheral function. Additionally, increased adiposity and reduced lean mass are linked to decreased oxygen diffusion capacity and impaired oxygen uptake kinetics in HFrEF patients.

Variable positive end-expiratory pressure in an experimental model of acute respiratory distress syndrome: an advanced ventilation modality.

Background: Introducing variability in tidal volume, ventilatory frequency, or both is beneficial during mechanical ventilation in acute respiratory distress syndrome (ARDS). We investigated whether applying cycle-by-cycle variability in the positive end-expiratory pressure (PEEP) exerts beneficial effect on lung function in a model of ARDS. Methods: Rabbits with lung injury were randomly allocated to receive mechanical ventilation for 6 h by applying a pressure-controlled mode with constant PEEP of 7 cm H2O (PC group: n=6) or variable PEEP (VEEP) with a coefficient of variation of 21.4%, range 4-10 cm H2O (PC-VEEP group; n=6). Lung oxygenation index (Pao2/FiO2) after 6 h of ventilation (H6) was the primary outcome and respiratory mechanics, lung volume, intrapulmonary shunt, and lung inflammatory markers were secondary outcomes. Results: After lung injury, both groups presented moderate-to-severe ARDS (Pao2/FiO2 <27 kPa). The Pao2/FiO2 was significantly higher in the PC-VEEP group than in the PC group at H6 (12.3 [sd 3.5] vs 19.2 [7.2] kPa, P=0.013) and a lower arterial partial pressure of CO2 at 1-3 h (P<0.02). The ventilation-induced increases in airway resistance and tissue elastance were prevented by PC-VEEP. There was no evidence for a difference in minute volume, driving pressure, end-tidal CO2, lung volumes, intrapulmonary shunt fraction, and cytokines between the ventilation modes. Conclusions: Prolonged mechanical ventilation with cycle-by-cycle VEEP prevents deterioration in gas exchange and respiratory mechanics in a model of ARDS, suggesting the benefit of this novel ventilation strategy to optimise gas exchange without increasing driving pressure and lung overdistension.

Radiographic scores as a predictor of oxygenation index in very low-birthweight infants.

BACKGROUND: Very low birthweight infants (VLBWIs) often undergo chest radiographic examinations without standardization or objectivity. This study aimed to assess the association of two radiographic scores, the Brixia and radiographic assessment of lung edema (RALE), with oxygenation index (OI) in ventilated VLBWIs and to determine the optimal cutoff values to predict hypoxic respiratory severity. METHODS: VLBWIs who received invasive respiratory support with arterial lines between January 2010 and October 2023 were enrolled in this study (n = 144). The correlation between the Brixia or RALE scores and OI was investigated. Receiver operating characteristic curve analysis was performed to determine the optimal cutoff points of the two radiographic scores for predicting OI values (OI ≥5, ≥10, and ≥15). RESULTS: The enrolled infants had a median gestational age of 27 weeks (interquartile range [IQR], 25-28 weeks) and a median birthweight of 855 g (IQR, 684-1003 g). Radiographic scoring methods correlated with the OI (Brixia score: r = 0.79, p < 0.001; RALE score: r = 0.72, p < 0.001). The optimal cutoff points for predicting OI values were as follows: Brixia score: OI ≥5, 10; OI ≥10, 13; OI ≥15, 15; RALE score: OI ≥5, 22; OI ≥10, 31; and OI ≥15, 40. CONCLUSIONS: Brixia and RALE scores are useful predictive markers of the oxygenation status in intubated VLBWIs with stable hemodynamics. These scores are easy to use and promising tools for clinicians to identify patients with a higher risk of hypoxic respiratory failure.

Oxygenation Index and Oxygen Saturation Index for Predicting Postoperative Outcome in Patients Undergoing Emergency Surgery: A Prospective Cohort Study.

Background: The OI was originally evaluated as a prognostic tool for acute hypoxemic respiratory failure in children and was an independent predictor for mortality in adult patients with acute respiratory distress syndrome (ARDS). Methods: Oxygenation index and OSI of 201 adult patients undergoing emergency surgery were evaluated at different time points. The primary objective of this study was to find the correlation between OI and OSI. The secondary objectives were to find the prognostic utility of OI and OSI for postoperative mechanical ventilation and mortality. Results: Significant statistical correlation was found between OI and OSI both at the beginning (r 2 = 0.61; p < 0.001) and immediately after surgery (r 2 = 0.47; p < 0.001). Oxygen saturation index at the beginning [area under the receiver operating characteristics curve (AUROC) (95% CI) 0.76 (0.62-0.89); best cutoff 3.9, sensitivity 64% and specificity 45%] and immediately after surgery [AUROC (95% CI) 0.82 (0.72-0.92); best cutoff 3.57, sensitivity 79%, and specificity 62%] were reasonable predictors of the requirement of invasive ventilatory support. Exploratory analysis reported that older age (p = 0.02), higher total leukocyte count (p = 0.002), higher arterial lactate (p = 0.02), and higher driving pressure (p < 0.001) were independently associated with hospital mortality. Conclusion: In adult patients undergoing emergency laparotomy under general anesthesia, OI and OSI were found to be correlated. Both metrics demonstrated reasonable accuracy in predicting the need for invasive ventilatory support beyond 24 hours and hospital mortality. How to cite this article: Thakuria R, Ernest EE, Chowdhury AR, Pangasa N, Kayina CA, Bhattacharjee S, et al. Oxygenation Index and Oxygen Saturation Index for Predicting Postoperative Outcome in Patients Undergoing Emergency Surgery: A Prospective Cohort Study. Indian J Crit Care Med 2024;28(7):645-649.

Relationship between neonatal respiratory distress syndrome pulmonary ultrasonography and respiratory distress score, oxygenation index, and chest radiography grading.

BACKGROUND: Accurate condition assessment is critical for improving the prognosis of neonatal respiratory distress syndrome (RDS), but current assessment methods for RDS pose a cumulative risk of harm to neonates. Thus, a less harmful method for assessing the health of neonates with RDS is needed. AIM: To analyze the relationships between pulmonary ultrasonography and respiratory distress scores, oxygenation index, and chest X-ray grade of neonatal RDS to identify predictors of neonatal RDS severity. METHODS: This retrospective study analyzed the medical information of 73 neonates with RDS admitted to the neonatal intensive care unit of Liupanshui Maternal and Child Care Service Center between April and December 2022. The pulmonary ultrasonography score, respiratory distress score, oxygenation index, and chest X-ray grade of each newborn before and after treatment were collected. Spearman correlation analysis was performed to determine the relationships among these values and neonatal RDS severity. RESULTS: The pulmonary ultrasonography score, respiratory distress score, oxygenation index, and chest X-ray RDS grade of the neonates were significantly lower after treatment than before treatment (P < 0.05). Spearman correlation analysis showed that before and after treatment, the pulmonary ultrasonography score of neonates with RDS was positively correlated with the respiratory distress score, oxygenation index, and chest X-ray grade (ρ = 0.429-0.859, P < 0.05). Receiver operating characteristic curve analysis indicated that pulmonary ultrasonography screening effectively predicted the severity of neonatal RDS (area under the curve = 0.805-1.000, P < 0.05). CONCLUSION: The pulmonary ultrasonography score was significantly associated with the neonatal RDS score, oxygenation index, and chest X-ray grade. The pulmonary ultrasonography score was an effective predictor of neonatal RDS severity.

Can Noninvasive Oxygen Saturation Index Match Invasive Oxygenation Index to Monitor Respiratory Disease in Critically Ill Children?-A Prospective Study.

Respiratory illnesses are common indications for mechanical ventilation in children. The adequacy of ventilatory support for oxygenation is measured using arterial blood gas analysis and calculation of oxygenation index (OI). Due to invasive nature of arterial blood sampling needed to calculate OI, several researchers have replaced blood gas-derived partial pressure of oxygen values with oxygen saturation (SpO 2 ) obtained from pulse oximetry. This noninvasive index called oxygen saturation index (OSI) is found to be useful in neonates. Studies in pediatric population are lacking. In this prospective study on mechanically ventilated children, both OI and OSI were determined and compared against alveolar-arterial oxygen difference (AaDO 2 ). A total of 29 children were studied. Both OSI and OI had good correlation of 0.787 and 0.792 with AaDO 2 , respectively. OSI of 7.3 and 9.4 had good sensitivity and specificity for AaDO 2 cutoffs of 344 and 498, which represents moderate and severe respiratory illness, respectively. The correlation coefficients of both OSI and OI are similar against AaDO 2 . OSI can be used instead of OI for constant monitoring of children on mechanical ventilation. Arterial blood gas analysis and calculation of OI can be reserved for situations where SpO 2 measurement is unreliable.

The utility of the respiratory rate-oxygenation index as a predictor of treatment response in dogs receiving high-flow nasal cannula oxygen therapy.

Objective: This study aims to evaluate the respiratory rate-oxygenation index (ROX) and the ratio of pulse oximetry saturation (SpO2) to the fraction of inspired oxygen (FiO2) (SpO2/FiO2, [SF]) to determine whether these indices are predictive of outcome in dogs receiving high-flow nasal cannula oxygen therapy (HFNOT). Design: This is a prospective observational study. Setting: This study was carried out at two university teaching hospitals. Animals: In total, 88 dogs treated with HFNOT for hypoxemic respiratory failure due to various pulmonary diseases were selected. Measurements and main results: The ROX index was defined as the SF divided by the respiratory rate (RR). ROX and SF were calculated at baseline and for each hour of HFNOT. The overall success rate of HFNOT was 38% (N = 33/88). Variables predicting HFNOT success were determined using logistic regression, and the predictive power of each variable was assessed using the area under the receiver operating curve (AUC). ROX and SF were adequately predictive of HFNOT success when averaged over 0-16 h of treatment, with similar AUCs of 0.72 (95% confidence interval [CI] 0.60-0.83) and 0.77 (95% CI 0.66-0.87), respectively (p < 0.05). SF showed acceptable discriminatory power in predicting HFNOT outcome at 7 h, with an AUC of 0.77 (95% CI 0.61-0.93, p = 0.013), and the optimal cutoff for predicting HFNC failure at 7 h was SF ≤ 191 (sensitivity 83% and specificity 76%). Conclusion: These indices were easily obtained in dogs undergoing HFNOT. The results suggest that ROX and SF may have clinical utility in predicting the outcomes of dogs on HFNOT. Future studies are warranted to confirm these findings in a larger number of dogs in specific disease populations.

Body Size, Cerebral Blood Flow, Ambient Temperature, and Relative Brain Temperatures in Newborn Infants under Incubator Care.

Subtle changes in body temperature affect the outcomes of ill newborns. However, the temperature profile of neonatal brains remains largely unknown. In open-cot care, increased cerebral perfusion is correlated with higher superficial brain temperatures. This study investigated the dependence of brain temperature (relative to rectal temperature) on ambient temperature, body size, cerebral perfusion, and metabolism in infants receiving incubator care. Rectal, scalp, and brain temperatures, superior vena cava flow, and brain oxygenation were assessed using echocardiography, thermo-compensatory temperature monitoring, and near-infrared spectroscopy in 60 newborns. These infants had a mean postconceptional age of 36.9 (2.2) weeks and weighed 2348 (609) g at the time of evaluation. The ambient temperature was maintained at 30.0 (1.0) °C. A higher rectal temperature was associated with greater postconceptional age (p = 0.002), body weight (p < 0.001), and head circumference (p < 0.001). Relative scalp, superficial brain, and deep brain temperatures were associated with smaller head circumference (p < 0.001, p = 0.030, and p = 0.015, respectively) and superior vena cava flow (p = 0.002, p = 0.003, and p = 0.003, respectively). In infants receiving incubator care, larger head sizes and increased brain perfusion were associated with lower relative scalp and brain temperatures. When considered alongside previous reports, cerebral perfusion may contribute to maintaining stable cerebral tissue temperature against ambient temperature changes.

The correlation between lung ultrasound scores and outcomes of high-flow nasal cannula therapy in infants with severe pneumonia.

OBJECTIVE: The study aimed to explore the effectiveness of bedside lung ultrasound (LUS) combined with the PaO2/FiO2 (P/F) ratio in evaluating the outcomes of high-flow nasal cannula (HFNC) therapy in infants with severe pneumonia. METHODS: This retrospective study analyzed the clinical data of 150 infants diagnosed with severe pneumonia and treated with HFNC therapy at our hospital from January 2021 to December 2021. These patients were divided into two groups based on their treatment outcomes: the HFNC success group (n = 112) and the HFNC failure group (n = 38). LUS was utilized to evaluate the patients' lung conditions, and blood gas results were recorded for both groups upon admission and after 12 h of HFNC therapy. RESULTS: At admission, no significant differences were observed between the two groups in terms of age, gender, respiratory rate, partial pressure of oxygen, and partial pressure of carbon dioxide. However, the P/F ratios at admission and after 12 h of HFNC therapy were significantly lower in the HFNC failure group (193.08 ± 49.14, 228.63 ± 80.17, respectively) compared to the HFNC success group (248.51 ± 64.44, 288.93 ± 57.17, respectively) (p < 0.05). Likewise, LUS scores at admission and after 12 h were significantly higher in the failure group (18.42 ± 5.3, 18.03 ± 5.36, respectively) than in the success group (15.09 ± 4.66, 10.71 ± 3.78, respectively) (p < 0.05). Notably, in the success group, both P/F ratios and LUS scores showed significant improvement after 12 h of HFNC therapy, a trend not observed in the failure group. Multivariate regression analysis indicated that lower P/F ratios and higher LUS scores at admission and after 12 h were predictive of a greater risk of HFNC failure. ROC analysis demonstrated that an LUS score > 20.5 at admission predicted HFNC therapy failure with an AUC of 0.695, a sensitivity of 44.7%, and a specificity of 91.1%. A LUS score > 15.5 after 12 h of HFNC therapy had an AUC of 0.874, with 65.8% sensitivity and 89.3% specificity. An admission P/F ratio < 225.5 predicted HFNC therapy failure with an AUC of 0.739, 60.7% sensitivity, and 71.1% specificity, while a P/F ratio < 256.5 after 12 h of HFNC therapy had an AUC of 0.811, 74.1% sensitivity, and 73.7% specificity. CONCLUSION: Decreased LUS scores and increased P/F ratio demonstrate a strong correlation with successful HFNC treatment outcomes in infants with severe pneumonia. These findings may provide valuable support for clinicians in managing such cases.

Novel Oxygenation and Saturation Indices for Mortality Prediction in COVID-19 ARDS Patients: The Impact of Driving Pressure and Mechanical Power.

Background: The oxygenation index (OI) and oxygen saturation index (OSI) are proven mortality predictors in pediatric and adult patients, traditionally using mean airway pressure (Pmean). We introduce novel indices, replacing Pmean with DP (ΔPinsp), MPdyn, and MPtot, assessing their potential for predicting COVID-19 acute respiratory distress syndrome (ARDS) mortality, comparing them to traditional indices. Methods: We studied 361 adult COVID-19 ARDS patients for 7 days, collecting ΔPinsp, MPdyn, and MPtot, OI-ΔPinsp, OI-MPdyn, OI-MPtot, OSI-ΔPinsp, OSI-MPdyn, and OSI-MPtot. We compared these in surviving and non-surviving patients over the first 7 intensive care unit (ICU) days using Mann-Whitney U test. Logistic regression receiver operating characteristic (ROC) analysis assessed AUC and CI values for ICU mortality on day three. We determined cut-off values using Youden's method and conducted multivariate Cox regression on parameter limits. Results: All indices showed significant differences between surviving and non-surviving patients on the third day of ICU care. The AUC values of OI-ΔPinsp were significantly higher than those of P/F and OI-Pmean (P values .0002 and <.0001, respectively). Similarly, AUC and CI values of OSI-ΔPinsp and OSI-MPdyn were significantly higher than those of SpO2/FiO2 and OSI-Pmean values (OSI-ΔPinsp: P < .0001, OSI-MPdyn: P values .047 and .028, respectively). OI-ΔPinsp, OSI-ΔPinsp, OI-MPdyn, OSI-MPdyn, OI-MPtot, and OSI-MPtot had AUC values of 0.72, 0.71, 0.69, 0.68, 0.66, and 0.64, respectively, with cut-off values associated with hazard ratios and P values of 7.06 (HR = 1.84, P = .002), 8.04 (HR = 2.00, P ≤ .0001), 7.12 (HR = 1.68, P = .001), 5.76 (HR = 1.70, P ≤ .0001), 10.43 (HR = 1.52, P = .006), and 10.68 (HR = 1.66, P = .001), respectively. Conclusions: Critical values of all indices were associated to higher ICU mortality rates and extended mechanical ventilation durations. The OI-ΔPinsp, OSI-ΔPinsp, and OSI-MPdyn indices displayed the strongest predictive capabilities for ICU mortality. These novel indices offer valuable insights for intensivists in the clinical management and decision-making process for ARDS patients.

Prone position ventilation for the relief of acute respiratory distress syndrome through improved pulmonary ventilation: Efficacy and safety.

BACKGROUND: At present, there is a preliminary clinical consensus that prone position ventilation (PPV) is beneficial to the treatment of acute respiratory distress syndrome (ARDS), and further research on the details of treatment and patients' benefits will help to assess its effectiveness and safety. AIM: To evaluate the timing, efficacy, and safety of different mechanical ventilation positions (MVP) in treating ARDS. STUDY DESIGN: The results of clinical trials were directly or indirectly compared by network meta-analysis to compare the effects of different MVP. Two authors independently searched the papers published in PubMed, Embase, Cochrane Library, China Knowledge Infrastructure (CNKI), China Biomedical Discs (CBM), WanFang, and VIP database from January 2000 to August 2022. The outcome indicators were oxygenation index, mechanical ventilation time, ICU hospitalization time, in-hospital mortality, and incidence of adverse events. Two authors independently screened the literature, evaluated the quality of the studies, and completed the data extraction. Stata 14.0 was used to conduct a network Meta-analysis, and the intervention measures were ranked according to the surface under the cumulative ranking curve (SUCRA). Funnel plots were drawn to evaluate publication bias. RESULTS: According to the inclusion and exclusion criteria, 75 studies (including 6333 patient data) were finally included. According to the analysis results, PPV was the best for improving the oxygenation index. The SUCRA values of mechanical ventilation time, ICU hospitalization time, and in-hospital mortality were ranked as PPV > lateral position ventilation (LPV) > supine position ventilation (SuPV) > semireclining position ventilation (SePV). The SUCRA values in the incidence of adverse events were ranked as LPV > PPV > SuPV > SePV. All outcome measures had good consistency and low statistical heterogeneity. Funnel plot analysis shows that papers reported within three days of mechanical ventilation time, over five days of mechanical ventilation time, and in-hospital mortality were more likely to have publication bias. CONCLUSIONS: PPV has the best effect on improving the oxygenation index, reducing mechanical ventilation time, shortening ICU hospitalization time, and reducing in-hospital mortality. Early and long-term use of PPV to improve pulmonary ventilatory function will be the key to improving patients' survival and quality of life with ARDS. RELEVANCE TO CLINICAL PRACTICE: PPV significantly affects patients with ARDS, which can shorten the treatment time and reduce hospital costs. During the treatment, nursing observation should be strengthened to prevent adverse events.

Effect of different hypoxic and hypobaric interventions on blood gas and erythrocyte-related indicators in rats. / ä¸åŒç¼ºæ°§å¹²é¢„å¯¹ä½ŽåŽ‹ä½Žæ°§æ¨¡åž‹é¼ è¡€æ°”åŠçº¢ç»†èƒžç›¸å ³æŒ‡æ ‡çš„å½±å“.

OBJECTIVES: To explore the effects of hypoxic and hypobaric conditions on blood gas and erythrocyte-related indicators in rats. METHODS: SD male rats were exposed to low-pressure hypoxic conditions simulating an altitude of 6500 m in a small or a large experimental cabin. Abdominal aortic blood samples were collected and blood gas indicators, red blood cells (RBCs) count, and hemoglobin (Hb) content were measured. The effects of exposure to different hypoxia times, different hypoxia modes, normal oxygen recovery after hypoxia, and re-hypoxia after hypoxia preconditioning on blood gas indicators, RBCs count and Hb content were investigated. RESULTS: The effect of blood gas indicators was correlated with the length of exposure time of hypoxia and the reoxygenation after leaving the cabin. Hypoxia caused acid-base imbalance and its severity was associated with the duration of hypoxia; hypoxia also led to an increase in RBCs count and Hb content, and the increase was also related to the time exposed to hypoxia. The effects of reoxygenation on acid-base imbalance in rats caged in a small animal cabin were more severe that those in a large experimental cabin. Acetazolamide alleviated the effects of reoxygenation after leaving the cabin. Different hypoxia modes and administration of acetazolamide had little effect on RBCs count and Hb content. Normal oxygen recovery can alleviate the reoxygenation and acid-base imbalance of hypoxic rats after leaving the cabin and improve the increase in red blood cell and hemoglobin content caused by hypoxia. The improvement of hypoxia preconditioning on post hypoxia reoxygenation is not significant, but it can alleviate the acid-base imbalance caused by hypoxia in rats and to some extent improve the increase in red blood cell and hemoglobin content caused by hypoxia. CONCLUSIONS: Due to excessive ventilation and elevated RBCs count and Hb content after hypoxia reoxygenation, oxygen partial pressure and other oxygenation indicators in hypoxic rats are prone to become abnormal, while blood gas acid-base balance indicators are relatively stable, which are more suitable for evaluating the degree of hypoxia injury and related pharmacological effects in rats.

Correlation and Prognostic Significance of Oxygenation Indices in Invasively Ventilated Adults (OXIVA-CARDS) with COVID-19-associated ARDS: A Retrospective Study.

Background: Oxygenation index [OI = (MAP × FiO2 × 100)/PaO2] assesses the severity of hypoxic respiratory failure. Oxygen saturation index [OSI = (MAP × FiO2 × 100)/SpO2] is a noninvasive method to assesses the severity of hypoxic respiratory failure. Conventionally used PaO2/FiO2 (P/F) ratio to measure the severity of ARDS requires arterial blood gas (ABG) sampling. It tenders limited prognostic information mandating the need for better markers. Oxygenation index (needs arterial sampling) and OSI (a noninvasive method) are substitutes to provide mortality information in ARDS patients. We evaluated the correlation between P/F, OI, and OSI in invasively ventilated COVID-19 ARDS patients (C-ARDS) and looked at its relationship with mortality. Patients and methods: A retrospective study of invasively ventilated C-ARDS >18 years of age managed in COVID ICU. Ventilator settings (FiO2, mean airway pressure), pulse oximetry (SpO2), and ABG values (PaO2) were simultaneously noted at the time of sample collection. Patient outcomes (alive and deceased) were documented. Differences in parameters between survivors and nonsurvivors were assessed using independent sample t-test. Receiver operating characteristic (ROC) analysis with Youden's index was used to identify cutoff values to determine survival. Results: A total of 1557 measurements for 203 patients were collected over the maximum duration of 21 days after ventilation. About 147 (72.4%) were males and 56 (27.6%) were females. On day one of ventilation, 161 (79.3%) had P/F ratio <200, 28 (13.8%) had P/F ratio between 200 and 300, and 14 (6.9%) had P/F ratio >300. There was a linear relationship between P/F ratio and OSI (r = -0.671), P/F and OI (r = -0.753), and OSI and OI (r = 0.893) (p < 0.001). After natural log transform, the correlation between these factors became stronger [P/F ratio and OSI (r = -0.797), PF and OI (r = -0.949), and OSI and OI (r = 0.902) (p < 0.001)]. About 74 (36.5%) patients survived. Survivors had significantly higher P/F ratio as compared with nonsurvivors (p < 0.05). Oxygen saturation index and OI were significantly lower in survivors as compared with nonsurvivors. Based on day-1 reading, a higher OSI (AUC = 0.719, 95% CI = 0.648-0.790) and OI (AUC = 0.752. 95% CI = 0.684-0.819) significantly can predict mortality. On the other hand, a higher P/F ratio can predict survival (AUC = 0.734, 95% CI = 0.664-0.805). P/F ratio of 160 on day 1 can predict survival. Oxygen saturation index values above 10.4% and OI above 13.5% were the cutoff derived for day 1 values to predict mortality. Conclusion: Noninvasive OSI can be used to assess the severity of hypoxic respiratory failure in C-ARDS without arterial access in resource-limited settings. Oxygen saturation index can noninvasively provide prognostic information in invasively ventilated C-ARDS patients. How to cite this article: Vadi S, Suthar D, Sanwalka N. Correlation and Prognostic Significance of Oxygenation Indices in Invasively Ventilated Adults (OXIVA-CARDS) with COVID-19-associated ARDS: A Retrospective Study. Indian J Crit Care Med 2023;27(11):801-805.

Evaluation of placental oxygenation by near-infrared spectroscopy in relation to ultrasound maturation grade in physiological term pregnancies.

A prospective observational study (ClinicalTrial ID: NCT05771415) was conducted to compare placental oxygenation in low-risk, uncomplicated term pregnancies measured by near-infrared spectroscopy (NIRS) in relation to the placental maturity grade determined by ultrasound assessment according to the Grannum scale. We included 34 pregnancies divided into two groups according to placental maturation. For each pregnancy, measurements were taken at the site above the central part of the placenta (test) and at the site outside of the placenta on the lower abdomen (control). Student's t-test was used to compare tissue oxygenation index (TOI) values among the study groups. The normality of distribution was proven by the Kolmogorov‒Smirnov test. In women with low placental maturity grade, the mean TOI value above the placenta was 70.38 ± 3.72, which was lower than the respective value in women with high placental maturity grade (77.99 ± 3.71; p < 0.001). The TOI values above the placenta and the control site were significantly different in both groups (70.38 ± 3.72 vs 67.83 ± 3.21 and 77.99 ± 3.71 vs 69.41 ± 3.93; p < 0.001). The results offer a new perspective on placental function based on specific non-invasive real-time oxygenation measurements. Unfortunately, and because of technical limitations, NIRS cannot yet be implemented as a routine clinical tool.

Predictive Factors of Oxygen Therapy Failure in Patients with COVID-19 in the Emergency Department.

Background: Most patients with coronavirus disease 2019 (COVID-19) pneumonia require oxygen therapy, including standard oxygen therapy and a high-flow nasal cannula (HFNC), in the Emergency Department (ED), and some patients develop respiratory failure. In the COVID-19 pandemic, the intensive care unit (ICU) was overburdening. Therefore, prioritizing patients who require intensive care is important. This study aimed to find predictors and develop a model to predict patients at risk of requiring an invasive mechanical ventilator (IMV) in the ED. Methods: We performed a retrospective, single-center, observational study. Patients aged ≥18 years who were diagnosed with COVID-19 and required oxygen therapy in the ED were enrolled. Cox regression and Harrell's C-statistic were used to identifying predictors of requiring IMV. The predictive model was developed by calculated coefficients and the ventilator-free survival probability. The predictive model was internally validated using the bootstrapping method. Results: We enrolled 333 patients, and 97 (29.1%) had required IMV. Most 66 (68.0%) failure cases were initial oxygen therapy with HFNC. Respiratory rate-oxygenation (ROX) index, interleukin-6 (IL-6) concentrations ≥20 pg/mL, the SOFA (Sequential Organ Failure Assessment) score without a respiratory score, and the patient's age were independent risk factors of requiring IMV. These factors were used to develop the predictive model. ROX index and the predictive model at 2 hours showed a good performance to predict oxygen therapy failure; the c-statistic was 0.814 (95% confidence level [CI] 0.767-0.861) and 0.901 (95% CI 0.873-0.928), respectively. ROX index ≤5.1 and the predictive model score ≥8 indicated a high probability of requiring IMV. Conclusion: The COVID-19 pandemic was limited resources, ROX index, IL-6 ≥20 pg/mL, the SOFA score without a respiratory score, and the patient's age can be used to predict oxygen therapy failure. Moreover, the predictive model is good at discriminating patients at risk of requiring IMV and close monitoring.

Construction and application of prone position ventilation management scheme for severe COVID-19 patients.

Background: Prone position ventilation (PPV) can significantly improve oxygenation index and blood oxygen saturation in most (70%-80%) patients with acute respiratory distress syndrome. However, although PPV is not an invasive procedure, there are many potential PPV-related complications, such as nerve compression, crush injury, venous stasis (e.g., facial oedema), pressure sores, retinal damage, vomiting, and arrhythmia, with an incidence of up to 56.9%. Nursing managers have focused on reducing the occurrence of PPV-related complications and improving safety. Objective: To construct a prone ventilation management scheme for patients with severe coronavirus disease 2019 (COVID-19) and analyse its application effect. Methods: Based on a previous evidence-based study combined with the COVID-19 Diagnosis and Treatment Protocol (Trial Edition 9), a prone ventilation management protocol for severe COVID-19 was formulated and applied to COVID-19 patients in the intensive care unit of a designated hospital. A prospective self-control study was used to compare changes in the oxygenation index and other outcome indicators before and after the intervention. Results: The oxygenation index of patients after intervention (321.22 ± 19.77 mmHg) was significantly higher (p < 0.05) than before intervention (151.59 ± 35.49 mmHg). The difference in oxygenation index in different prone position ventilation durations was statistically significant (p < 0.05). Nursing quality evaluation indicators showed that the implementation rate of gastric residual volume assessment was 100% and the incidence of occupational exposure and cross-infection was 0%; the incidences of pressure ulcers, drug extravasation, and facial oedema were 13.64% (3/22), 4.54% (1/22), and 4.54% (1/22), respectively. The incidence of unplanned extubation, aspiration, and falls/falls was 0%.