Phillips Hallowell

Cardiovascular Response to Large Doses of Intravenous Morphine in Man

Abstract Large doses of intravenous morphine (0.5 to 3.0 mg per kilogram of body weight) were used alone or in combination with inhalation anesthetic agents for anesthesia in over 1100 patients undergoing open-heart surgery. Morphine, 1 mg per kilogram, was administered intravenously to seven subjects with aortic-valve disease and eight without major heart or lung disease. The cardiac subjects had higher control pulse rates and lower control stroke indexes than the normal subjects. In the cardiac but not in the normal subjects, significant increases in cardiac index, stroke index, central venous pressure, and pulmonary-artery pressure, and a significant decrease in systemic vascular resistance, were observed after morphine was administered, suggesting that large doses of morphine may be used with safety in patients with minimal circulatory reserve.

The Effect of Hemodilution with Albumin or Ringer's Lactate on Water Balance and Blood Use in Open-Heart Surgery

To determine the effect of intraoperative albumin administration on blood use, water balance, and postoperative clinical course, we studied two groups of adult cardiac surgical patients. Group I (30 patients) received 25 gm of albumin during withdrawal of 2 units of blood prior to cardiopulmonary bypass (CPB) and 50 gm of albumin in the oxygenator prime. Group II (32 patients) received no albumin prior to the end of CPB. No difference in clinical course could be identified, nor was there a significant difference in blood use. Group I patients had lower hematocrit values intraoperatively from the time of blood withdrawal until the conclusion of operation. Coronary artery bypass operations were associated with greater positive water balance than were heat valve operations. Forty-three percent of the patients having coronary artery bypass grafting had a positive water balance greater than 5 liters, whereas 50% of those undergoing valve procedures had a balance less than 3 liters. We conclude that the principal effect of withholding albumin under these circumstances is to increase net positive water balance. The greater positive water balance does not appear to be detrimental.

Arterial Oxygenation During Hypothermia

The aims of this stady were: to investigate a possible significant relation between the size of the tidal volume during constant volume ventilation and the rate of change of the alveolar-arterial oxygen tension gradient (AaDO2): to determine whether hypothermia significantly affects this relationship; and to test the accuracy of correction factors previously proposed for the effect of temperature on the oxygen tension of fully saturated blood. Ten patients were surface cooled to 30° C. for over 24 hours. Anesthesia consisted of pentobarbital sodium and d-tubocurarine. Constant volume pulmonary ventilation with 100 per cent oxygen was provided by a piston pump. A significant relationship (P < 0.01) was found between the size of the constant tidal volume and the rate of increase or decrease of the AaDO2. This relation showed little evidence of being affected by hypothermia per se. The accuracy of previously determined temperature correction factors for oxygen tension was confirmed.