Systolic Blood Pressure Threshold for HEMS-Witnessed Arrests

Comparison of Changes in Vital Signs During Ground and Helicopter Emergency Medical Services and Hospital Interventions

OBJECTIVE

Few studies have evaluated the effects of helicopter emergency medical services (HEMS) alone. This single-center study compared the changes in vital signs during ground emergency medical services (GEMS), HEMS, and hospital interventions to assess the impact of HEMS interventions.

METHODS

This retrospective observational study included 168 trauma patients older than 18 years of age who received HEMS. Patients with cardiac arrest or those who received medical attention before HEMS were excluded. We assessed 3 intervention phases (GEMS, HEMS, and hospital). The changes in heart rate, systolic blood pressure, respiratory rate, and shock index in response to interventions were calculated and divided by the intervention time, and the changes observed during the interventions were compared.

RESULTS

No changes in vital signs were observed when receiving GEMS. Systolic blood pressure increased and shock index decreased after HEMS, whereas systolic blood pressure decreased and shock index increased during hospital interventions. Heart rate showed no significant change (P = .12), and respiratory rate showed very little change. Systolic blood pressure increased significantly during HEMS compared with the pre- and postintervention periods.

CONCLUSION

Changes in vital signs differed according to the intervention. Systolic blood pressure increased during HEMS but not with GEMS or hospital interventions.

Vital sign patterns before shock-related cardiopulmonary arrest

OBJECTIVE

Traditional vital sign thresholds reflect an increased risk of mortality, which may occur hours, days, or weeks following illness/injury, limiting immediate clinical significance to guide rescue therapy to avoid arrest. Our objective is to explore vital sign patterns prior to arrest due to shock.

DESIGN

This retrospective observational analysis utilized physiological data from adult helicopter patients suffering provider-witnessed arrest. Pre-arrest values for systolic blood pressure (SBP), mean arterial pressure (MAP), heart rate (HR), shock index, and end-tidal carbon dioxide (EtCO2) were modeled against time using polynomial linear regression. The "terminal inflection point" beyond which arrest was imminent was identified where slope equals 1.0 (shock index) or -1.0 (SBP, MAP, HR, EtCO2) and was then compared to initial values.

SETTING

Air ambulance services.

PATIENTS

70 helicopter patients over age fourteen suffering cardiac arrest.

RESULTS

SBP and MAP demonstrated a gentle decline followed by acceleration beyond the inflection point (SBP 80.7 mmHg, MAP 61.9 mmHg). HR demonstrated an increase followed by a terminal drop, but inflection point values fell within normal range. Shock index increased gradually from a mean of 0.9 to the inflection point of 1.1. Initial EtCO2 values declined gradually from normal (34.4 mmHg) to the inflection point (24.7 mmHg), then dropped precipitously into arrest. All inflection points occurred 2-5 min prior to arrest.

CONCLUSIONS

Vital sign patterns were defined for SBP, MAP, HR, shock index, and EtCO2 with clear inflection points identified 2-5 min prior to arrest. These patterns may help guide therapy to reverse deterioration and prevent arrest.

Push Dose Epinephrine Use in the Management of Hypotension During Critical Care Transport

Introduction: Hypotension is a critical event during the transport of critically ill patients. Push dose vasopressor use, though widely adopted by anesthesiologists, has only recently found use in the field of emergency medicine and may have utility in the management of out-of-hospital hypotension. This study aimed to characterize the hemodynamic effects and adverse events that occur following push dose epinephrine (PDE) administration by critical care transport (CCT) providers to correct documented hypotension. Methods: We performed a retrospective observational study of patients transported by a regional critical care transport service and who received PDE during transport to correct documented hypotension. Per protocol, 10-20 µg of 1:100,000 epinephrine was given intravenously every 2 min until: (1) the systolic blood pressure (SBP) was at least 90 mmHg, or (2) the mean arterial pressure (MAP) was 65 mmHg or greater. All patients were over 18 years of age and were transported between January 1, 2015 and December 31, 2016. Primary outcomes of interest were the primary diagnoses associated with PDE use, hemodynamic outcomes of the intervention, and adverse events. Results: During the study period 100 doses of push dose epinephrine were given during the transport of 58 patients. Of these, 94 (94.0%) were found to be appropriately dosed and indicated per protocol. The most common diagnoses associated with PDE use were: post-cardiac arrest (n = 24), sepsis (n = 9), altered mental status (n = 7), and cardiogenic shock (n = 3). The median increase in MAP across all doses was 13.0 (5.0-34.0) mmHg, and the heart rate increase was 2.0 (-1.0-9.3) beats per minute. Hypotension was resolved in 55 of 94 instances (58.5%). A single episode of transient extreme hypertension occurred after one PDE dose and did not result in patient harm. Conclusions: Push dose epinephrine may be an effective method of temporarily resolving hypotension during the CCT of critically ill patients. In the cases where PDE was administered, there was close adherence to the established protocol and adverse events were found to be rare directly following PDE administration. Further research is needed to validate these findings, establish optimal dosing, and evaluate use in non-CCT prehospital settings.