Feasibility of preclinical cardiac output and systemic vascular resistance in HEMS in thoracic pain—the ultrasonic cardiac output monitor

Abstract 

Background

Cardiac output (CO) and systemic vascular resistance (SVR) are important hemodynamic parameters in emergency patients and for clinical early goal-directed therapy. This study evaluated the feasibility of CO and SVR determination using preclinical continuous wave Doppler ultrasound in a helicopter emergency medical service (HEMS) on emergency patients presenting with or without thoracic pain as a pilot observational study.

Methods

Forty-four consecutive medical emergency patients (62.8 ± 22 years of age, 23 males) were classified at the scene as with (15 patients, 69 ± 14 years of age, 40% male) or without (29 patients, 60 ± 25 years of age, 59% male) thoracic pain by an emergency physician. Hemodynamic parameters were determined based on continuous wave Doppler noninvasively (USCOM, Sydney, Australia): stroke volume (SV), CO, cardiac index (CI), minute distance (MD), and SVR.

Results

Noninvasive SV, MD, CO, CI, and SVR determination is feasible using preclinical ultrasound in HEMS. Thoracic pain patients had higher SVR (2,709 ± 891 vs 1,499 ± 661 dyne*sec*cm-5) and lower CO/CI (3.37 ± 1.1 vs 5.06 ± 2.9 L/min, CI: 1.67 ± 0.58 vs 3.18 ± 1.34 L/min/m2) as well as a reduced aortic minute distance (11.2 ± 3.3 m/min vs 19.1 ± 8 m/min, P = .001) than patients without thoracic pain. Highest cardiac outputs were measured during and within 30 minutes after seizures (n = 5, 7.5 ± 3.05 L/min). The range of CO measured in six cardiopulmonary resuscitation patients was 2.7 to 12 L/min; the level of CO was not associated with the establishing of sustained circulation.

Conclusions

Determining SV, CO/CI, and SVR in different emergency situations in HEMS using rapid CW Doppler ultrasound is feasible. Thoracic pain patients have increased SVR and lower CO/CI and reduced aortic minute distance than do non–thoracic pain patients in the preclinical setting.