Marcel Boulanger

Fentanyl-Oxygen Anaesthesia for Coronary Artery Surgery: Cardiovascular and Antidiuretic Hormone Responses

This study demonstrates that large doses of fentanyl, as the sole anaesthetic with ventilation with oxygen, produces complete anaesthesia and minimal changes in cardiovasuclar dynamics in patients with coronary artery disease. It also indicates that high dose fentanyl anaesthesia blocks the increase in plasma anti-diuretic hormone and cardiovascular dynamics which are so common with morphine and other anaesthetic techniques during tracheal intubation and surgical stimulation in patients with coronary artery disease. Our findings suggest that fentanyl-oxygen anaesthesia is an attractive technique in patients with coronary artery disease.

Coronary Artery Spasm and Perioperative Cardiac Arrest

There has been increasing interest in coronary artery spasm as etiopathogenic mechanism for various syndromes associated with myocardial ischemia. A case with documented organic coronary artery disease is presented, in which coronary artery spasm was the probable cause of intraoperative and early postoperative cardiac arrest. We recommend that coronary spasm be considered in the differential diagnosis of perioperative cardiac arrest.

Hemodynamics during Diazepam Induction of Anesthesia for Coronary Artery Bypass Grafting

The hemodynamics during induction of anesthesia were studied in ten patients with ischemic heart disease about to have coronary artery bypass grafting. Intravenous diazepam, 0.5 mg/kg (with 50% N2O in oxygen inspired and pancuronium IV), was used to induce anesthesia. Compared to awake baseline, induction caused statistically significant decreases in the mean arterial pressure, rate pressure product, stroke index, and left and right ventricular stroke work indexed. Although statistically significant, the hemodynamic changes were small and transient and required no modifying treatment. This anesthetic induction technic is safe, efficient, and well tolerated by patients having myocardial revascularization surgery.

Postoperative Respiratory Care: A Controlled Trial of Early and Late Extubation following Coronary-Artery Bypass Grafting

Sequelae of early versus late extubation of the trachea in patients following coronary-artery bypass grafting were compared prospectively in 38 patients randomly assigned to one of the two groups. The times to extubation were 2 ± 2 and 18 ± 3 hours after operation for the two groups. Comparisons were made between groups for the following five variables: time spent in the intensive care unit; drug utilization in the intensive care unit; cardio-pulmonary morbidity; hemodynamic performance; patient stress (plasma norepinephrine levels). The anesthetic technique consisted of induction with thiopental, nitrous oxide, and halothane, followed by maintenance with nitrous oxide and halothane. Pancuronium was the only muscle relaxant administered. Patients whose tracheas were extubated early had muscle relaxants reversed prior to the application of extubation criteria. There was no significant difference between the groups in times spent in the intensive care unit, hemodynamic performances, or plasma norepinephrine levels; however, the patients whose tracheas were extubated early received less morphine and diazepam and suffered significantly less cardio-pulmonary morbidity

Pharmacologic Antagonism of Beta-Adrenergic Blockade in Dogs. I. Hemodynamic Effects of Isoproterenol, Dopamine, and Epinephrine in Acute Propranolol Administration

Hemodynamic effects of isoproterenol, dopamine, and epinephrine were studied before and after acute beta-adrenergic blockade in 16 open-chest, anesthetized mongrel dogs. Beta blockade was induced with 1 mg. per kilogram of intravenous propranolol. Cardiac output measurements were obtained by thermal dilution, and pressure recordings were obtained in the right ventricle, pulmonary artery, left atrium, left ventricle, and aorta. Derived parameters included stroke volume, pulmonary and systemic vascular resistances, and peak left ventricular dP/dt. In the presence of propranolol, epinephrine became a lethal drug in large doses and did not increase cardiac output in standard doses. Dopamine, in 25 to 50 mcg. per kilogram per minute doses, increased arterial pressure and systemic resistance; cardiac output was diminished compared with dopamine, 10 mcg. per kilogram per minute, prior to propranolol, as a result of increased resistance and decreased LV contractility. Isoproterenol, 0.6 to 0.9 mcg. per kilogram per minute, 15 to 20 times standard dosages, had moderately positive inotropic effects and increased cardiac output. Left ventricular systolic pressure with isoproterenol after propranolol was reduced when compared with effects of smaller doses prior to propranolol. These observations suggest that none of the catecholamines studied would be optimal for circulatory support in heart failure in the presence of propranolol. The present results define a pharmacologic basis for design of appropriate drug combinations for circulatory support in beta-blocked animals.

REGIONAL MYOCARDIAL FUNCTION IN THE CONSCIOUS DOG DURING ACUTE CORONARY OCCLUSION AND RESPONSES TO MORPHINE, PROPRANOLOL, NITROGLYCERIN, AND LIDOCAINE

Regional myocardial function following occlusions of the circumflex coronary artery was studied in unanesthetized dogs using miniature ultrasonic crystal pairs implanted subendocardially within the left ventricle for measurement of control, marginal, and ischemic lengths. As early as five beats after coronary occlusion, reduced function was apparent in ischemic zones, and an increase in heart rate occurred (78 to 115 beats/min) at an average of 25 sec. In the control zones, shortening initially increased from a constant end-diastolic length, but later end-diastolic length also increased by 7.5%. Shortening in the marginal zones was reduced by 50% at 90 sec as holosystolic expansion developed in the ischemic zones. On reperfusion, systolic function returned to normal within a few minutes while protodiastolic abnormalities persisted for up to 45 min. With coronary occlusions longer than two minutes most dogs exhibited arousal and further tachycardia; this reaction was prevented by morphine. During two minute occlusions morphine also decreased the heart rate increase by 37%, and marginal segment shortening was improved by 40%. Prior administration of propranolol also decreased heart rate during coronary occlusion and produced similar improvement in marginal segment function; however, in contrast to morphine, there was depression of contraction in the control segments. Nitroglycerin given during coronary occlusion caused decreases in end-diastolic length of all segments and increased shortening in the marginal segment by 28%. Lidocaine administered during coronary occlusion produced a mild depression of myocardial function in all regions of the heart.

NITROUS OXIDE AS AN ANALGESIC IN ACUTE MYOCARDIAL INFARCTION

Nitrous oxide in a concentration of 35% has been shown to ameliorate the pain of acute myocardial infarction. This conclusion was reached on the basis of a double-blind study in 69 patients and a clinical study in an additional 42 patients. The use of nitrous oxide was not accompanied by hemodynamic changes or significant adverse reactions.