Nitroglycerin in the out-of-hospital treatment of chest pain

Adverse events after prehospital nitroglycerin administration in a nationwide registry analysis

OBJECTIVE

Nitroglycerin (NTG) is a vasodilator used in the prehospital setting with chest pain patients. Potential adverse effects include hypotension, bradycardia or tachycardia, and mental status change. However, it is unclear which factors, if any, are associated with patients having an adverse event after receiving NTG. The objective of this study was to determine demographic and clinical factors associated with adverse events after prehospital NTG administration.

METHODS

The ESO Data Collaborative (Austin, TX), containing records from 1322 EMS agencies, was queried for 911 encounters where NTG was administered to patients ≥18 years old by EMS. Adverse event outcomes were defined as a new systolic blood pressure (SBP) < 90, heart rate (HR) < 50 or > 120, mean arterial pressure (MAP) < 65, or change in mental status following NTG administration. Descriptive statistics and logistic regression models adjusting for age, sex, race, ethnicity, intravenous (IV) access, and initial vital signs were used to assess for adverse event-related factors.

RESULTS

Among 80,760 encounters, the mean age was 61 (IQR 50-72), with 52% males, 71% white race, and 7% Hispanic ethnicity. Adverse events occurred in 7% of encounters. Adverse events were found to be less common among Black patients (OR = 0.74, 95%CI:0.69-0.80). IV access obtained prior to NTG administration was associated with fewer adverse events (OR = 0.92, 95%CI:0.85-0.99). Increasing age (OR = 1.02, 95%CI:1.01-1.02) and HR (OR = 1.03, 95%CI:1.02-1.03) were associated with increased odds of adverse events while SBP (OR = 0.99, 95%CI:0.98-0.99) was inversely associated.

CONCLUSIONS

Adverse events following prehospital NTG administration were rare, especially in patients with an SBP > 110 and a HR < 100, and less frequent in those with existing IV access. Demographics were not found to be clinically significant.

Is pre-hospital treatment of chest pain optimal in acute coronary syndrome? The relief of both pain and anxiety is needed

BACKGROUND

Many patients who suffer from acute chest pain are transported by ambulance. It is not known how often treatment prior to hospital admission is optimal and how optimal pain-relieving treatment is defined. It is often difficult to delineate pain from anxiety.

AIM

To describe various aspects of chest pain in the pre-hospital setting with the emphasis on a) treatment and b) presumed acute coronary syndrome.

METHODS

In the literature search, we used PubMed and the appropriate key words. We included randomised clinical trials and observational studies.

RESULTS

Four types of drug appear to be preferred: 1) narcotic analgesics, 2) nitrates, 3) beta-blockers and 4) benzodiazepines. Among narcotic analgesics, morphine has been associated with the relief of pain at the expense of side-effects. Alfentanil was reported to produce more rapid pain relief. Nitrates have been associated with the relief of pain with few side-effects. Beta-blockers have been reported to increase the relief of pain when added to morphine. The combination of beta-blockers and morphine has been reported to be as effective as beta-blockers alone in pain relief, but this combination therapy was associated with more side-effects. Experience from anxiety-relieving drugs such as benzodiazepines is limited. It is not known how these 4 drugs should be combined. The results indicate that various pain-relieving treatments might modify the disease.

CONCLUSION

Our knowledge of the optimal treatment of chest pain and associated anxiety in the pre-hospital setting is insufficient. Recommendations from existing guidelines are limited. Large randomised clinical trials are warranted.