Influence of patient body weight on the probability of return of spontaneous circulation following out-of-hospital cardiac arrest: an exploratory analysis.

INTRODUCTION

In addition to key interventions, including bystander CPR and defibrillation, successful resuscitation of out-of-hospital cardiac arrest (OHCA) is also associated with several patient-level factors, including a shockable presenting rhythm, younger age, Caucasian race and female sex. An additional patient-level factor that may influence outcomes is patient weight, yet this attribute has not been extensively studied within the context of OHCA, despite globally increasing obesity rates.

OBJECTIVE

To assess the relationship between patient weight and return of spontaneous circulation (ROSC) during OHCA.

METHODS

This retrospective study included adult patients from a national emergency medical services (EMS) patient record, with witnessed, non-traumatic OHCA prior to EMS arrival from January to December 2020. Logistic regression was used to evaluate the relationship between patient weight and ROSC.

RESULTS

Complete records were available for 9096 patients, of which 64.3% were males and 25.3% were ethnic minorities. The mean age of the participants was 65.01 years (SD = 15.8), with a mean weight of 93.52 kg (SD = 31.5). Altogether, 81.8% of arrests were of presumed cardiac aetiology and 30.3% presented with a shockable rhythm. Bystander CPR and automated external defibrillator (AED) shock were performed in 30.6% and 7.3% of cases, respectively, and 44.0% experienced ROSC. ROSC was less likely with patient weight >100 kg (OR = 0.709, p <0.001), male sex (OR = 0.782, p <0.001), and increasing age and EMS response time (OR = 0.994 per year, p <0.001 and OR = 0.970 per minute, p <0.001, respectively). Patients with shockable rhythms were more likely to achieve ROSC (OR = 1.790, p <0.001), as were patients receiving bystander CPR (OR = 1.170, p <0.001) and defibrillation prior to EMS arrival (OR = 1.658, p <0.001). Although the mean first adrenaline dose (mg/kg) followed a downward trend due to its non-weight-based dosing scheme, the mean total adrenaline dose administered to achieve ROSC demonstrated an upward linear trend of 0.05 mg for every 5 kg of body weight.

CONCLUSIONS

Patient weight was negatively associated with ROSC and positively associated with the total adrenaline dose required to attain ROSC.