Effects of prehospital nitroglycerin on hemodynamics and chest pain intensity.

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.

Impact of interventions for patients refusing emergency medical services transport.

OBJECTIVE: To evaluate the effect of a documentation checklist and on-line medical control contact on ambulance transport of out-of-hospital patients refusing medical assistance. METHODS: Consecutive patients served by four suburban ambulance services who initially refused emergency medical services (EMS) transport to the hospital were prospectively enrolled. In phase 1 (control phase), all patients who initially refused medical attention or transport had an identifying data card completed. In phase 2 (documentation phase), out-of-hospital providers completed a similar data card that contained a checklist of high-risk criteria for a poor outcome if not transported. In phase 3 (intervention phase), a data card similar to that used in phase 2 was completed, and on-line medical control was contacted for all patients with high-risk criteria who refused transport. The primary endpoint was the percentage of patients transported to the hospital. RESULTS: A total of 361 patients were enrolled. Transport rate varied by phase: control, 17 of 144 (12%); documentation, 11 of 150 (7%); and intervention, 12 of 67 (18%) (chi-square, p = 0.023). Transport of high-risk patients improved with each intervention: control, two of 60 (3%); documentation, seven of 70 (10%); and intervention, 12 of 34 (35%) (chi-square, p = 0.00003). Transport of patients without high-risk criteria decreased with each intervention: control, 15 of 84 (18%); documentation, four of 80 (5%); and intervention, 0 of 33 (0%) (p = 0.0025). Of the 28 patients for whom medical control was contacted, 12 (43%) were transported to the hospital, and only three of these 12 patients (25%) were released from the ED. CONCLUSION: Contact with on-line medical control increased the likelihood of transport of high-risk patients who initially refused medical assistance. The appropriateness of the decreased transport rate of patients not meeting high-risk criteria needs further evaluation.

Colorimetric end-tidal CO2 detector for verification of endotracheal tube placement in out-of-hospital cardiac arrest.

OBJECTIVE: To evaluate the ability of a disposable, colorimetric end-tidal CO2 detector to verify proper endotracheal (ET) tube placement in out-of-hospital cardiac arrest, and to correlate semiquantitative CO2 measurements with the rate of return of spontaneous circulation (ROSC). METHODS: Prospective, observational study using a convenience sample of intubated out-of-hospital cardiac arrest patients. A disposable, colorimetric end-tidal CO2 detector was attached to the ET tube after intubation. In the absence of a colorimetric change, the paramedics reassessed the tube placement and could reintubate the patient. Tube placement was verified at the hospital. Paramedics were instructed to contact the base station and report the colorimetric change upon hospital arrival. ROSC was defined as restoration of a self-sustaining pulse until hospital arrival. RESULTS: Between December 1990 and May 1993, ET tubes were placed in 566 victims of out-of-hospital cardiac arrest. 541 of the 566 intubations (95.6%) were associated with a color change. In one case with a color change and out-of-hospital clinical evidence of proper tube placement, the tube was determined to be in the esophagus at the hospital. Correct placement of the remaining 565 of 566 (99.8%) tubes was verified. Of the 566 patients who had a colorimetric change, 91 (16%) had ROSC vs one of 25 (4%) patients who did not have a color change. In one subgroup (n = 179), the degree of color change was highly associated with ROSC (p = 0.004). CONCLUSIONS: A disposable, colorimetric end-tidal CO2 detector appears reliable in verifying proper ET tube placement in victims of out-of-hospital cardiac arrest. The degree of color change correlates with the probability of ROSC.

On-line telemetry: prospective assessment of accuracy in an all-volunteer emergency medical service system.

OBJECTIVE: To evaluate the need for on-line telemetry control in an all-volunteer, predominantly advanced emergency medical technician (A-EMT) ambulance system. METHODS: Emergency medical service (EMS) advanced life support (ALS) providers were asked to transmit the ECG rhythms of monitored patients over a six-month period in 1993. The ECG rhythm interpretations of volunteer EMS personnel were compared with those of the on-line medical control physician. All discordant readings were reviewed by a panel of physicians to decide whether the misdiagnosis would have resulted in treatment aberrations had transmission been unavailable. RESULTS: Patients were monitored and rhythms were transmitted in 1,825 cases. 1,642 of 1,825 rhythms were correctly interpreted by the EMS providers (90%; 95% CI 89-91%). The accuracy of the EMS providers was dependent on the patient's rhythm (chi-square, p < 0.00001), the chief complaint (chi-square, p = 0.0001), and the provider's level of training (chi-square, p = 0.02). Correct ECG rhythm interpretations were more common when the out-of-hospital interpretation was sinus rhythm (95%), ventricular fibrillation (87%), paced rhythm (94%), or agonal rhythm (96%). The EMS providers were frequently incorrect when the out-of-hospital rhythm interpretation was atrial fibrillation/flutter (71%), supraventricular tachycardia (46%), ventricular tachycardia (59%), or atrioventricular block (50%). Of the 183 discordant cases, 124 (68%) involved missing a diagnosis of, or incorrectly diagnosing, atrial fibrillation/flutter. Review of the discordant readings identified 11 cases that could have resulted in treatment errors had the rhythms not been transmitted, one of which might have resulted in an adverse outcome. CONCLUSIONS: In this all-volunteer, predominantly A-EMT ALS system, patients with a field interpretation of a sinus rhythm do not require ECG rhythm transmission. Field interpretations of atrial fibrillation/flutter, supraventricular tachycardia, ventricular tachycardia, and atrioventricular blocks are frequently incorrect and should continue to be transmitted.