Increased weight in patients with time-sensitive diagnosis is associated with longer prehospital on-scene times

Obesity is a growing epidemic associated with higher rates of metabolic disease, heart disease and all-cause mortality. Heavier patients may require more advanced resources and specialized equipment. We hypothesize that increasing patient weight will be associated with longer prehospital on-scene times.

We reviewed electronic patient care records for patients transported by two urban 9-1-1 emergency medical services (EMS) agencies. We collected age, sex, estimated patient weight, vital signs (systolic blood pressure, heart rate, pulse oximetry), provider impression, method of moving patient to ambulance, and on-scene times. We selected patients with time-sensitive diagnoses of stroke, ST-segment elevation myocardial infarction (STEMI), and trauma and compared on-scene times for patients who weighed above or below 300 pounds. We performed descriptive statistics, Mann-Whitney U tests for continuous variables and Chi-square tests for discrete variables. We constructed a generalized linear model to determine the effect of patient weight adjusted for covariates.

For a three-year period (May 1, 2018 to April 30, 2021) 48,203 patients were transported with an EMS impression of stroke, ST-segment elevation myocardial infarction (STEMI), and trauma. 23,654 (49.1%) patients were female, and the median age was 52 (IQR 34-68) years. The median weight was 175.0 (IQR 150.0-205.0) pounds. Patients above a dichotomous weight categorization of 300 pounds experienced a longer median scene time with any time-sensitive diagnosis (12.6 versus 11.9 min p < 0.001), STEMI (16.0 versus 13.1 min, p = 0.014) and blunt trauma (12.6 versus 11.9 min, p < 0.001)). They were more likely to be hypoxic (p < 0.001) and more likely to experience cardiac arrest (p < 0.001). They were less likely to walk to the ambulance (22.1% versus 32.2%, p < 0.001).

Patient weight above 300 pounds was associated with significantly longer on-scene time. These patients were more likely to be hypoxic, sustain a cardiac arrest, and less likely to walk to the ambulance.