J Korean Soc Emerg Med.  2021 Aug;32(4):281-289.

Predictors of intubation and mechanical ventilation in patients with acute respiratory failure treated with high flow nasal cannula in emergency room: the usefulness of arterial blood gas analysis

• Jang JG
• Park YS
• Park HY
• Hwang TS

Abstract

Objective
The use of a high flow nasal cannula (HFNC) might cover the gap between conventional oxygen therapy and mechanical ventilation in the management of acute respiratory failure patients and could be a significant factor in determining patient outcomes. Early predictors of HFNC failure may help a clinician decide whether to shift the patient to a mechanical ventilator. We aimed at identifying the predictors associated with HFNC failure and the application of a mechanical ventilator using arterial blood gas analysis (ABGA).
Methods
We retrospectively analyzed patients who were admitted to the emergency room at a single center with respiratory distress and a PaO₂/FiO₂ ratio (ratio of arterial partial pressure of oxygen to fraction of inspired oxygen) of less than 300. Comparing keeping and weaning HFNC groups with the escalation group, we sought to identify a few discriminating factors. Initial ABGA was done when the patients entered the emergency room and this was followed up within 2 hours after HFNC therapy.
Results
Two hundred and eighteen patients were enrolled and of these HFNC therapy succeeded in 153 and failed in 65. At baseline Glasgow Coma Scale, follow-up (F/U) pH, ΔpH, and F/U respiratory rate-oxygenation index were lower and pro-brain natriuretic peptide, initial lactate, F/U lactate, ΔPCO₂, heart rate, acidosis, consciousness, oxygenation, respiratory rate score, Acute Physiology And Chronic Health Evaluation score, Simplified Acute Physiology Score, and Sequential Organ Failure Assessment score were significantly higher in the HFNC failure group. The results of the multivariate analysis indicated that initial lactate (odds ratio [OR], 1.215; 95% confidence interval [CI], 1.081-1.366; P=0.001) and ΔpH (OR, 0.000; 95% CI, 0.000-0.018; P<0.001) were independently associated with the prediction of application of the mechanical ventilator.
Conclusion
Patients who had higher initial lactate levels and insufficiently corrected pH after HFNC therapy may need to be monitored carefully and escalation of oxygen therapy may need to be considered.

Keyword

High flow nasal cannula; Acute respiratory failure; Predictor; Arterial blood gas analysis