Calcium: limited indications, some danger.

Calcium chloride has been advocated since the 1920s for the resuscitation of asystole, electromechanical dissociation (EMD), and ventricular fibrillation. Reports of side effects and complications have been numerous. Studies of calcium assays following American Heart Association recommended dosages have shown dangerously elevated serum levels. Large retrospective clinical studies in Milwaukee and Tampa have found no evidence of improved survival with calcium chloride in asystole and EMD. A prospective randomized double-blind study comparing calcium chloride and saline controls in the Milwaukee Paramedic system for asystole and EMD using standard AHA protocols showed no statistically significant difference in resuscitation rates or long-term survival between the calcium and no-calcium groups for the rhythm of asystole. Although patients with EMD had statistically improved resuscitation rates when calcium chloride was given, only one of the patients survived to hospital discharge. Because of the low rates of resuscitation and long-term survival in patients presenting in asystole and EMD, proving that calcium chloride does not enhance survival would require large multicenter trials. However, since no controlled study has ever documented significant benefit, its routine use in asystole and EMD cannot be supported. Calcium has long been used in medical treatment of hypocalcemic and hyperkalemic states and should be administered in moribund patients who have the proper clinical history and clinical signs of hypocalcemia.

Lack of effectiveness of calcium chloride in refractory asystole.

The effectiveness of calcium chloride in asystole has been challenged; retrospective studies have not supported its use. We conducted a prospective, randomized, blinded study comparing the effectiveness of calcium chloride with saline in the prehospital paramedic setting. Seventy-three patients who had received epinephrine, bicarbonate, and atropine and were in refractory asystole were included in the study, which was conducted from October 1982 to October 1983. Traumatic and pediatric arrests were excluded. The successful resuscitation rate was three of 39 in the calcium group versus one of 34 in the saline group (P less than .37). A successful resuscitation was defined as the conveyance of a patient with a pulse and a rhythm to an emergency department. Groups were analyzed for sex, age, and witnessed arrests. There was no statistically significant difference between the groups. No patient who was resuscitated successfully in the field was discharged from the hospital alive. We conclude that calcium chloride is not of value in resuscitating patients from refractory asystole in the prehospital cardiac arrest setting.

The effectiveness of calcium chloride in refractory electromechanical dissociation.

The effectiveness of calcium in electromechanical dissociation (EMD) has been challenged. Retrospective studies have been contradictory. To determine its effectiveness a prospective, randomized, blinded study comparing calcium chloride and saline in refractory EMD was carried out in the pre-hospital setting from October 1982 to October 1983. Only patients who had received epinephrine and bicarbonate and were refractory were entered in the study. All trauma and pediatric arrests were excluded. Ninety patients presented in refractory EMD. Overall, eight of 48 who received calcium were resuscitated successfully in the field; two of 42 who received saline were resuscitated successfully (P less than .07). A successful resuscitation was defined as the conveyance of a patient with a pulse and a rhythm to an emergency department. Patients were analyzed for age, sex, and witnessing of arrest. There was no statistical difference in demographic data. When the group of EMD patients was broken down into subgroups based on the width of QRS, it was noted that patients with a QRS width less than 0.12 did not respond to calcium, whereas the successfully resuscitated in the group with widened QRS or ischemic changes (N = 70) was eight of 39, compared with one of 31 not receiving calcium (P less than .028). Only one patient who was resuscitated successfully was discharged from the hospital alive. Calcium has been shown to be effective in the cardiac resuscitation of patients in refractory EMD. There may be a subset of patients with widened QRS complexes or ischemic changes who will benefit to a greater extent from the use of calcium chloride.

Atropine in asystole: human studies.

Current research supporting the use of atropine for asystole is limited. Reported in the literature are the cases of 26 patients who presented with a rhythm of asystole. Of these, only eight were clearly in refractory asystole after epinephrine and sodium bicarbonate, only seven were prehospital patients, and only two were delineated as being intubated. Despite such limited data, atropine has been advocated for asystole, and use of the drug is included in the recommendations of the American Heart Association. We undertook a retrospective review of our prehospital experience with refractory asystole for a four-year period from January 1979 to December 1982. All patients with trauma or poisoning and all pediatric arrests were excluded. All patients who received calcium chloride during resuscitation also were excluded. One hundred seventy patients presented in cardiorespiratory arrest with an initial rhythm of asystole. Of these, 84 remained in refractory asystole after receiving epinephrine and sodium bicarbonate. Forty-three patients in this group received atropine. The successful resuscitation rate in the atropine group was 14% (6/43), while in the control group it was 0% (0/41) (P less than .04). A successful resuscitation was defined as conveyance of a patient with a rhythm and a pulse to an emergency department. Patients were compared for age, sex, witnessing of arrest, cardiac history, and cardiac drugs. No other significant differences were noted between groups. No patient who received atropine for refractory asystole was discharged alive.

Calcium chloride: reassessment of use in asystole.

Calcium chloride has been advocated since the 1920s for resuscitation of asystole and ventricular fibrillation. Most reports have been anecdotal, and have failed to substantiate its effectiveness. In two large retrospective series with a collective experience of 181 patients, investigators reviewed the effectiveness of calcium chloride in asystole and did not support its use. A prospective, randomized, double-blind study comparing calcium chloride with saline in the prehospital setting was done. Patients with trauma or pediatric arrests were excluded. During the period from October 1982 to October 1983, a total of 32 patients with witnessed arrests presented with a rhythm of asystole and were refractory to epinephrine, bicarbonate, and atropine. The rate of successful resuscitation in the calcium group was 5.6% (1/18), and there were no successful resuscitations (0/14) in the saline group (P = .37). A successful resuscitation was defined as conveyance of a patient with a rhythm and pulse to an emergency department. Groups were analyzed for sex, age, cardiac history, and cardiac drugs, and there were no statistically significant differences. No patient who was successfully resuscitated in the field was discharged alive from the hospital. Calcium chloride is of no value in resuscitating refractory asystole in the prehospital cardiac arrest setting.