Evaluation of Out-of-Hospital Use of a Valsalva Assist Device in the Emergency Treatment of Supraventricular Tachycardia

Abstract

Study objectives: A simple device might help patients perform a more effective Valsalva maneuver for the treatment of supraventricular tachycardia (SVT) and reduce the need for further emergency treatment. We aimed to determine whether the availability of the device within an out-of-hospital emergency medical (ambulance) service reduced the percentage of patients, treated for SVT, conveyed to hospital.

Methods: We conducted a pragmatic, stepped wedge cluster randomized trial in adult patients treated with a Valsalva maneuver for suspected SVT by an ambulance service in the United Kingdom. The intervention was the availability of a simple Valsalva device for use by the ambulance service during usual care. Clusters were ambulance stations, and the study had 5 time periods, each of 4 months' duration. Eighty clusters were randomized to 1 of 4 sequences that determined the point that they crossed from the control to the intervention condition. The primary outcome was conveyance to hospital.

Results: Between July 1, 2022, and February 29, 2024, 865 eligible participants were recruited. A total of 430 participants were treated by clinicians in the intervention condition and 435 in the standard treatment control condition. There was no evidence that the availability of a Valsalva device reduced conveyance to hospital: adjusted odds ratio (95% confidence interval; P-value) was 1.37 (0.75 to 2.49; P=.30).

Conclusion: The availability of this device did not reduce conveyance to hospital in this study. We cannot rule out potential benefits in different settings but did not find sufficient evidence to support ongoing routine device availability in this ambulance service.

Keywords: Cluster randomized trial; Emergency care; Stepped wedge trial; Supraventricular tachycardia; Valsalva maneuver.