Evaluating the use of the respiratory-rate oxygenation index as a predictor of high-flow nasal cannula oxygen failure in COVID-19.

BACKGROUND: It can be challenging for clinicians to predict which patients with respiratory failure secondary to coronavirus disease 2019 (COVID-19) will fail on high-flow nasal cannula (HFNC) oxygen and require escalation of therapy. This study set out to evaluate the association between the respiratory rate-oxygenation index (ROX) and HFNC failure in such patients and to assess whether ROX trajectory correlates with treatment failure. METHODS: This was a single-centre, retrospective, observational study of patients with COVID-19 requiring HFNC, conducted over a 3-month period. ROX was calculated as "pulse-oximetry oxygen saturation (SpO2) over the fractional inspired oxygen concentration (FiO2)/respiratory rate" for each patient at 2, 4, and 12 hours from starting HFNC. HFNC failure was defined as escalation to continuous positive airway pressure ventilation or invasive mechanical ventilation (IMV). Time-to-event analyses were performed to account for the longitudinal data set and time-dependent variables. RESULTS: We included 146 patients. Ninety-three (63.7%) experienced HFNC failure, with 53 (36.3%) requiring IMV. Higher ROX values were associated with a lower subhazard of HFNC failure on time-to-HFNC failure analysis (subhazard ratio, 0.29; 95% confidence interval [CI], 0.18-0.46; P<0.001). This remained true after controlling for informative censoring. Median ROX values changed differentially over time, increasing in the HFNC success group (0.06 per hour; 95% CI, 0.05-0.08; P<0.001) but not in the HFNC failure group (0.004 per hour; 95% CI, -0.05 to 0.08; P=0.890). CONCLUSIONS: A higher ROX is associated with a lower risk of HFNC failure. Monitoring ROX trajectory over time may help identify patients at risk of treatment failure. This has potential clinical applications; however, future prospective studies are required.

Lund University Cardiac Assist System Induced Liver Laceration and Anterior Cord Infarction After Cardiac Arrest: A Case Report.

We describe a hepatic laceration and subsequent anterior spinal artery syndrome in a 21-year-old man, secondary to prolonged cardiopulmonary resuscitation with a Lund University Cardiac Assist System (LUCAS2) mechanical cardiac compression device. We briefly review the current literature pertaining to hepatic injury from trauma due to cardiopulmonary resuscitation. The etiology of the anterior spinal artery syndrome in this patient is discussed. This case highlights that intra-abdominal causes of hypotension should be considered in patients after a prolonged resuscitation attempt. Extending focused cardiac ultrasound to exclude intra-abdominal free fluid should be routinely considered in these patients.