HyperOxic Therapy OR NormOxic Therapy after out-of-hospital cardiac arrest (HOT OR NOT): a randomised controlled feasibility trial

Abstract

Aims: To investigate the feasibility of delivering titrated oxygen therapy to adults with return of spontaneous circulation (ROSC) following out-of-hospital cardiac arrest (OHCA) caused by ventricular fibrillation (VF) or ventricular tachycardia (VT).

Methods: We used a multicentre, randomised, single blind, parallel groups design to compare titrated and standard oxygen therapy in adults resuscitated from VF/VT OHCA. The intervention commenced in the community following ROSC and was maintained in the emergency department and the Intensive Care Unit. The primary end point was the median oxygen saturation by pulse oximetry (SpO2) in the pre-hospital period.

Results: 159 OHCA patients were screened and 18 were randomised. 17 participants were analysed: nine in the standard care group and eight in the titrated oxygen group. In the pre-hospital period, SpO2 measurements were lower in the titrated oxygen therapy group than the standard care group (difference in medians 11.3%; 95% CI 1.0-20.5%). Low measured oxygen saturation (SpO2<88%) occurred in 7/8 of patients in the titrated oxygen group and 3/9 of patients in the standard care group (P=0.05). Following hospital admission, good separation of oxygen exposure between the groups was achieved without a significant increase in hypoxia events. The trial was terminated because accumulated data led the Data Safety Monitoring Board and Management Committee to conclude that safe delivery of titrated oxygen therapy in the pre-hospital period was not feasible.

Conclusions: Titration of oxygen in the pre-hospital period following OHCA was not feasible; it may be feasible to titrate oxygen safely after arrival in hospital.

Keywords: Cardiac arrest; Hyperoxia; Oxygen therapy.