Awake prone positioning for non-intubated patients with COVID-19-related acute hypoxic respiratory failure: a systematic review based on eight high-quality randomized controlled trials.

BACKGROUND: Awake prone positioning has been widely used in non-intubated patients with acute hypoxic respiratory failure (AHRF) due to COVID-19, but the evidence is mostly from observational studies and low-quality randomized controlled trials (RCTs), with conflicting results from published studies. A systematic review of published high-quality RCTs to resolve the controversy over the efficacy and safety of awake prone positioning in non-intubated patients with AHRF due to COVID-19. METHODS: Candidate studies were identified through searches of PubMed, Web of Science, Cochrane, Embase, Scopus databases from December 1, 2019 to November 1, 2022. Literature screening, data extraction and risk of bias assessment were independently conducted by two researchers. RESULTS: Eight RCTs involving 2657 patients were included. Meta-analysis of fixed effects models showed that awake prone positioning did not increase mortality(OR = 0.88, 95%CI [0.72, 1.08]), length of stay in ICU (WMD = 1.14, 95%CI [-0.45, 2.72]), total length of stay (WMD = 0.11, 95%CI [-1.02, 1.23]), or incidence of adverse events (OR = 1.02, 95%CI [0.79, 1.31]) compared with usual care, but significantly reduced the intubation rate (OR = 0.72, 95%CI [0.60, 0.86]). Similar results were found in a subgroup analysis of patients who received only high flow nasal cannula (Mortality: OR = 0.86, 95%CI [0.70, 1.05]; Intubation rate: OR = 0.69, 95%CI [0.58, 0.83]). All eight RCTs had high quality of evidence, which ensured the reliability of the meta-analysis results. CONCLUSIONS: Awake prone positioning is safe and feasible in non-intubated patients with AHRF caused by COVID-19, and can significantly reduce the intubation rate. More studies are needed to explore standardized implementation strategies for the awake prone positioning. TRIAL REGISTRATION: CRD42023394113.

[Prognostic value of arterial lactate combined with central venous-to-arterial carbon dioxide difference to arterial-to-central venous oxygen content difference ratio in septic shock patients].

OBJECTIVE: To evaluate the prognostic value of arterial lactate (Lac) combined with central venous-to-arterial carbon dioxide difference to arterial-to-central venous oxygen content difference ratio (Pcv-aCO2/Ca-cvO2) in patients with septic shock following early fluid resuscitation. METHODS: A total of 97 patients with septic shock admitted to intensive care unit (ICU) of Lanzhou University Second Hospital from January 2017 to December 2019 were enrolled. The Pcv-aCO2/Ca-cvO2 ratio was calculated from blood gas analysis of radial artery and superior vena cava which was performed before resuscitation and at 6 hours of resuscitation at the same time. The patients were divided into death group and survival group according to the 28-day prognosis. The baseline data, acute physiology and chronic health evaluation II (APACHE II) score, sequential organ failure score (SOFA), clinical therapy, lactate clearance rate (LCR) at 6 hours, the length of ICU stay, hemodynamics and oxygen metabolism parameters before and after resuscitation were compared between the two groups. Risk factors were analyzed by multivariate Cox regression for 28-day mortality of patients with septic shock. The receiver operating characteristic (ROC) curve was plotted to assess the prognostic values of these factors for 28-day mortality. RESULTS: (1) Compared with the survival group, the patients in the death group showed significantly higher levels of APACHE II score (23.96±4.31 vs. 17.70±3.92) and SOFA score (12.74±2.80 vs. 9.23±2.43, both P < 0.01), significantly higher proportions of mechanical ventilation [85.2% (23/27) vs. 50.0% (35/70)] and continuous renal replacement therapy [CRRT; 51.9% (14/27) vs. 25.7% (18/70), both P < 0.05], a significantly more fluid replacement at 6 hours (L: 2.92±0.24 vs. 2.63±0.25, P < 0.01), a significantly lower level of LCR at 6 hours [(11.61±7.76)% vs. (27.67±13.71)%, P < 0.01], and a shorter length of ICU stay (days: 6.37±2.70 vs. 7.67±2.31, P < 0.05). (2) Compared with the survival group, the patients before resuscitation in the death group showed a significantly lower level of mean arterial pressure [MAP (mmHg, 1 mmHg = 0.133 kPa): 52.63±4.35 vs. 55.74±3.01, P < 0.01], significantly higher levels of Lac and Pcv-aCO2/Ca-cvO2 ratio [Lac (mmol/L): 7.13±1.75 vs. 5.22±1.36, Pcv-aCO2/Ca-cvO2 ratio: 1.67±0.29 vs. 1.48±0.22, both P < 0.01]; and the patients at 6 hours of resuscitation in the death group showed a significantly lower level of MAP (mmHg: 62.59±4.80 vs. 66.71±3.91, P < 0.01), significantly higher levels of central venous pressure (CVP), Lac, Pcv-aCO2 and Pcv-aCO2/Ca-cvO2 ratio [CVP (mmHg): 10.74±1.40 vs. 8.80±0.75, Lac (mmol/L): 6.36±1.86 vs. 3.90±1.95, Pcv-aCO2 (mmHg): 7.59±2.02 vs. 4.34±1.37, Pcv-aCO2/Ca-cvO2 ratio: 1.87±0.51 vs. 1.03±0.27, all P < 0.01]. (3) Multivariate Cox regression analysis showed that the independent risk factors for 28-day mortality in patients with septic shock were Lac and Pcv-aCO2/Ca-cvO2 ratio whether before or at 6 hours of resuscitation [Lac before resuscitation: relative risk (RR) = 1.434, 95% confidence interval (95%CI) was 1.070-1.922, P = 0.016; Lac at 6 hours of resuscitation: RR = 1.564, 95%CI was 1.202-2.035, P = 0.001; Pcv-aCO2/Ca-cvO2 ratio before resuscitation: RR = 2.828, 95%CI was 1.108-4.207, P = 0.038; Pcv-aCO2/Ca-cvO2 ratio at 6 hours of resuscitation: RR = 4.386, 95%CI was 2.842-5.730, P = 0.000]. (4) ROC curve analysis showed that Lac and Pcv-aCO2/Ca-cvO2 ratio at 6 hours of resuscitation had predictive value for the prognosis of patients with septic shock, the area under ROC curve (AUC) was 0.849 (95%CI was 0.762-0.914) and 0.905 (95%CI was 0.828-0.955), respectively. However, the predictive value of Lac combined with Pcv-aCO2/Ca-cvO2 ratio in patients with septic shock was significantly higher than Lac [AUC (95%CI): 0.976 (0.923-0.996) vs. 0.849 (0.762-0.914), Z = 3.354, P = 0.001], the sensitivity was 97.14%, and the specificity was 88.89%. CONCLUSIONS: Lac and Pcv-aCO2/Ca-cvO2 ratio are independent risk factors for predicting 28-day mortality in patients with septic shock. Lac combined with Pcv-aCO2/Ca-cvO2 ratio can assess the prognosis of patients with septic shock more accurately.