Biomedical subjects
Publications and source records attributed to B D Amey.
Calcium is recommended by American Heart Association standards for the resuscitation of patients with electromechanical dissociation (EMD). Until recently, only anecdotal case reports were offered to support this recommendation. Recent studies examining the question of whether calcium is useful in resuscitating hearts in EMD are reviewed.
Bretylium tosylate is recommended by the American Heart Association Standards for Advanced Cardiac Life Support for refractory ventricular fibrillation after countershock, sodium bicarbonate, and epinephrine. According to this protocol, paramedics gave five to six milligrams per kilogram of intravenous bretylium by bolus in 96 patients with refractory fibrillation over a 24-month period. A positive response was defined as the presence of a palpable pulse following bretylium and countershock. Thirty-five percent of patients (34/96) responded following bretylium. Twenty-one percent (20/96) responded only temporarily with a rhythm and pulse. Fifteen percent (14/96) maintained a stable rhythm and vital signs on admission to the hospital, but only five patients, 5% of the total population, (5/96), were eventually discharged home. Clinical variables were similar in non-responders, temporary responders, and those admitted, but the times from the onset of Advanced Cardiac Life Support to receiving bretylium were 23.5 min, 20.3 min, and 14.3 min respectively. We conclude that about one-third of patients in refractory ventricular fibrillation respond following bretylium and countershock and that earlier bretylium use may give better results.
All records of cardiac arrest patients presenting to the Tampa EMS system for the 24-month period of January, 1980, through December, 1982, were reviewed. Paramedics were given direct orders or standing orders to administer calcium intravenously or intracardiac in patients in ventricular fibrillation, asystole, or electromechanical dissociation. Of the 480 patients receiving calcium for the above conditions, only patients with electromechanical dissociation responded to calcium. Twenty-seven EMD patients responded positively with the immediate return of blood pressure and pulse. Fourteen of these patients arrived at the emergency department with stable vital signs; there were three long-term survivors. Adverse rhythm or rate changes were not noted following calcium use, and arrhythmias associated with digitalis excess were not seen in a small group of patients taking digoxin. Although long-term survivors are limited in this group of patients, positive hemodynamic responses were seen following calcium chloride administration in 10% of EMD patients and not at all in patients with asystole or ventricular fibrillation.
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The effects of 50% nitrous oxide and 50% oxygen and of 30% nitrous oxide and 70% oxygen were evaluated in 88 patients with significant pain while in the prehospital setting. Under the telemetry physicians' supervision, EMT-Ps directed patients in the technique of self-administration of the analgesic gas. Fifty percent (36/72) reported complete or almost complete amelioration of pain; all but 15% (11/72) reported some degree of relief. No patients experienced clinically deleterious side effects, although 48% (41/85) reported side effects, of which 90% were mild. The analgesic properties, lack of complications, quick onset and short duration of action, and acceptance by patients, physicians, and paramedics make N2O a nearly ideal analgesic agent for advanced life support use in the prehospital relief of significant pain.
The incidence of echocardiographically determined pericardial effusion was assessed in the early postmanual cardiopulmonary resuscitation (CPR) period in a group of patients resuscitated by advanced emergency medical technicians (EMT-P) from the Rescue Division of the Tampa Fire Department. The survival rate from out-of-hospital sudden death is comparable to that reported in other series. Twenty-six survivors of out-of-hospital sudden death had echocardiograms performed an average of 2.5 days (range 0-10) postCPR to determine the amount of pericardial effusion. Eight of the 26 (31%) patients had received intracardiac drugs during CPR administered by the EMT-Ps when physician-directed by radio. Of the 26, three (12%) were found to have very minimal pericardial effusions; all deemed insignificant. All three had alternate explanations for physiological or pathological causes of their effusions. One had received intracardiac drugs, but the pericardial effusion could be explained by congestive cardiomyopathy. Another had congestive cardiomyopathy, and the third had sustained a severe steering wheel injury to the chest. Thus, manual CPR with or without the use of intracardiac drugs does not appear to cause significant pericardial effusions in survivors of sudden cardiac death.
The intracardiac administration of medications in cardiac arrest is advocated when an intravenous route cannot be established. Although warnings of complications of this mode of therapy are reiterated throughout the literature, their careful documentation is lacking. Paramedics were trained to administer intracardiac medications, under strict criteria, in patients with prehospital sudden cardiac death. Long-term survivors who received intracardiac medications from paramedics were compared to a control group resuscitated by paramedics with intravenous medications alone. By far, the patients who received intracardiac medications were more nearly refractory to resuscitation because of the criteria for intracardiac medication use. Potential complications of the intracardiac route were identified and sought. However, complications were no more common in this group of patients than in the control group. Paramedics can successfully administer intracardiac medications when indicated.
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Since the inception of mobile coronary care units (MCCU), patients with sudden cardiac death (SCD) saved by advanced emergency medical technicians (EMT-A) can be studied retrospectively and prospectively. Forty-eight cases of SCD found in ventricular fibrillation (VF) were successfully resuscitated. Only 32% had a myocardial infarction. Most survivors were New York Heart Association (NYHA) class I or II. All class IV survivors with severe congestive heart failure died within 45 days. All class II survivors had angina as the limiting factor. Of all patients with VF, 23% survived. Eighty percent of survivors were class I or II and have resumed previous lifestyles. No clear cut symptom complex was identified. Rescue response time was generally less than five minutes. Intracardiac medications were administered without complications. Empirical administration of sodium bicarbonate correlated poorly with arterial blood gas determinations.
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