Predictors of success of high-flow nasal cannula in the treatment of acute hypoxemic respiratory failure

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.

Value of Rox Index to Predict Intubation and Intensive Care Unit Outcome in Patients with Respiratory Failure

BACKGROUND

Recent literature suggests that the respiratory rate oxygenation (ROX) index may be a useful parameter in predicting intubation indication in hypoxemic patients.

OBJECTIVE

In this study, we evaluated the accuracy of the ROX index in predicting intubation, length of stay in the ICU, and mortality in ICU patients with hypoxemic respiratory failure with and without hypercapnia.

METHODS

Single-centre retrospective cohort study of 290 patients, with a preliminary diagnosis of respiratory failure, who were treated with low flow oxygen systems. Demographics, medical history, clinical, laboratory, treatment, and prognostic data were obtained from the electronic records of the hospital. The ROX index was calculated at the time of ICU admission.

RESULTS

Thirty-seven percent of non-hypercapnic and 69% of hypercapnic patients were intubated (p:0.005). In hypercapnic patients, ROX: 6.9 had highest sensitivity (81%) and specificity (65%) values for intubation (p:0.005). In non-hypercapnic patients, ROX: 6.2 had the highest sensitivity (81%) and specificity (40%) values. While 11% of hypercapnic patients and 30% of non-hypercapnic patients were died (p:0.05), 22% of hypercapnic patients and 33% of non-hypercapnic patients stayed in the ICU longer than 14 days (p:0.044). The highest sensitivity and specificity values were found for mortality in hypercapnic patients; for ROX value of 5.94 (sensitivity:86%, specificity:61%) and for ICU stay longer than 14 days; for ROX value of 7.4 (sensitivity:71%, specificity:68%).

CONCLUSION

Results of our study suggest that ROX index calculated during ICU admission can be helpful in predicting intubation indication and length of ICU stay in patients with respiratory failure and hypercapnia may influence the cutoff values.