Prediction of Extubation Failure in COVID-19

Prognostic value of the oxygenation index measured during mechanical ventilation and weaning. A retrospective cohort study

The aim of this study was to investigate the predictive value of the ratio of oxygen saturation (ROX) index calculated during mechanical ventilation (MV) and the weaning period in evaluating readiness to weaning and the success of the spontaneous breathing trial (SBT), extubation, and mortality. We also compared the results of the ROX index calculated with partial arterial oxygen pressure (PaO2), arterial oxygen saturation (SaO2%), and probe oxygen saturation (SpO2%). In this retrospective cohort study, the ROX index was calculated by SpO2%, PaO2, and SaO2% separately using the ROX index formula (PaO2 or SaO2 or SpO2 /FiO2)/respiratory rate. ROX was calculated during the first three days of MV treatment and the weaning period daily (SBT). Positive end-expiratory pressure and peak inspiratory pressure values were also recorded during these measurements. These ROX values were used to analyze whether they predict weaning readiness, SBT, extubation failure (EF), and mortality. The study included 107 mechanically ventilated patients. Weaning could be tried in 64 (60%) of the 107 patients; 44 (69%) of the 64 patients succeeded, and extubation was performed. 19 (43%) of 44 patients had EF. ROX values calculated with PaO2 during MV and SBT predicted readiness to wean, EF, and mortality better than ROX values calculated with SaO2 and SpO2. ROX values calculated with PaO2 during the third day of MV had the highest sensitivity and specificity for EF (sensitivity: 81%, specificity: 70% for the ROX<11 value). The results of this study suggest that the calculation of ROX index, not only with SpO2% but also with arterial blood gas PaO2 and SaO2% values, may be helpful in predicting the weaning readiness evaluation, SBT, and extubation success and mortality. Further studies with more patients are necessary to verify and standardize these results.

Response of patients with acute respiratory failure caused by COVID-19 to awake-prone position outside the intensive care unit based on pulmonary involvement

OBJECTIVES

Since there are difficulties in establishing effective treatments for COVID-19, a vital way to reduce mortality is an early intervention to prevent disease progression. This study aimed to evaluate the performance of patients with COVID-19 with acute hypoxic respiratory failure according to pulmonary impairment in the awake-prone position, outside of the intensive care unit (ICU).

METHODS

A prospective observational cohort study was conducted on COVID-19 patients under noninvasive respiratory support. Clinical and laboratory data were obtained for each patient before the treatment and after they were placed in the awake-prone position. To identify responders and non-responders after the first prone maneuver, receiver operating characteristic curves with sensitivity and specificity of the PaO2/FiO2 and SpO2/FiO2 indices were analyzed. The maneuver was considered positive if the patient did not require endotracheal intubation for ventilatory assistance.

RESULTS

Forty-eight patients were included, and 64.6% were categorized as responders. The SpO2/FiO2 index was effective for predicting endotracheal intubation in COVID-19 patients regardless of lung parenchymal damage (area under the curve 0.84, cutoff point 165, sensitivity 85%, specificity 75%). Responders had better outcomes with lower hospital mortality (hazard ratio [HR]=0.107, 95% confidence interval [CI]: 0.012-0.93) and a shorter length of stay (median difference 6 days, HR=0.30, 95% CI: 0.13-0.66) after adjusting for age, body mass index, sex, and comorbidities.

CONCLUSIONS

The awake-prone position for COVID-19 patients outside the ICU can improve oxygenation and clinical outcomes regardless of the extent of pulmonary impairment. Furthermore, the SpO2/FiO2 index discriminates responders from non-responders to the prone maneuver predicting endotracheal intubation with a cutoff under or below 165.