Objective: To assess the effects of prehospital nitroglycerin (NTG) on vital signs and chest pain intensity.
Methods: A retrospective review of advanced life support (ALS) run sheets was performed in a suburban volunteer emergency medical services (EMS) system receiving 8,000 annual ALS calls. All consecutive patients who were administered NTG by EMS were included. Standardized forms were used to collect data on patient demographics, history, and physical exam. Patients assessed their chest pain (CP) before and after NTG on a verbal numeric scale of 0-10 from least to most severe. The presence of syncope, dysrhythmias, or profound hypotension [loss of peripheral pulses, a systolic blood pressure (SBP) of <90 mm Hg after NTG, or a drop of >100 mm Hg in BP] was noted. Results. One thousand six hundred sixty-two patients received NTG over 18 months, their mean age was 66 years, and 48% were female. Indications for NTG included CP (83%), dyspnea (45%), and congestive heart failure (20%). After NTG administration, the CP score decreased from 6.9 to 4.4 (mean difference = 2.6; 95% CI = 2.4 to 2.8). The CP completely resolved in 10% of the patients. Mean decreases in SBPs and diastolic BPs were 11.8 mm Hg (95% CI = 10.7 to 13.0) and 4.0 mm Hg (95% CI = 2.9 to 5.1). The mean pulse rate increased by 2.7 beats/min (95% CI = 0.6 to 4.9). There were 12 patients with adverse events [0.7% (95% CI = 0.4% to 1.3%)], including profound bradycardia and hypotension (1), transient drop in SBP of 100 mm Hg responding to fluids (6), post-NTG SBP <90 mm Hg (4), and syncope (1). There were no deaths in the prehospital setting.
Conclusions: Use of prehospital NTG appears safe. While NTG reduces CP, most patients have residual pain.