Comparison of Adsol and CPDA-1 blood preservatives during simulated massive resuscitation after hemorrhage in swine.

BACKGROUND: In recent years, there has been a change from the use of blood stored in CPDA-1 to the use of red cells (RBCs) stored in electrolyte mixtures, such as Adsol (AS-1 RBCs). However, because Adsol contains mannitol, as well as increased amounts of glucose relative to CPD and CPDA-1, concerns have been expressed as to possible harmful effects (recipient hyperglycemia, inappropriate osmotic diuresis) that it might induce under conditions of massive RBC transfusion. STUDY DESIGN AND METHODS: A hemorrhagic shock animal model was used to evaluate the effects of large-volume infusion of CPDA-1 or Adsol on glucose homeostasis and on urinary output under conditions that were devoid of extensive surgical manipulation. Hemorrhage was induced in 10 female Pitman-Moore mini-pigs to maintain mean arterial blood pressure at 55 mmHg for 90 minutes. After the return of autologous RBCs plus 1 L of 0.9-percent sodium chloride, the animals were given solution equivalent to the solute load in either 20 units of CPDA-1 whole blood (63 mL x 20 = 1260 mL) or 20 units of AS-1 RBCs (100 mL x 20 = 2000 mL) over a period of 90 minutes. Animals were monitored to determine physiologic and blood chemical responses to infusion of the solutions and to determine if there was hyperglycemia or inappropriate diuresis in the Adsol-treated group. RESULTS: Animals that received CPDA-1 developed significant hypocalcemia, arterial hypotension, and elevated blood glucose concentrations; two of five animals died of circulatory collapse. In contrast, glucose metabolism in the Adsol recipients was well-regulated, serum ionized calcium concentration was not significantly altered, and all animals survived. No evidence of inappropriate diuresis was observed. CONCLUSION: Administration of large amounts of Adsol was not associated with hyperglycemia or inappropriate osmotic duiresis in hemorrhaged and resuscitated minipigs. These data suggest that fewer physiologic changes may be associated with the massive transfusion of AS-1 RBCs than with that of CPDA-1 whole blood.

Cardiopulmonary gas transport and aging.

Pulmonary mechanics, ventilatory drive, and blood-oxygen transport are modified with age, but quantification of these changes and evaluation of their physiologic implications have been seriously limited. During acute and chronic physiologic stress, the respiratory and hemoglobin oxygen transport systems respond to facilitate tissue oxygenation. While these adaptive responses have been well documented in young adults, the level of their retention in the elderly is uncertain. Studies conducted to date have provided conflicting information. Some of this may have been the result of the limited number of subjects studied in each decade of life. Pulmonary and blood-biochemical changes occur gradually over many decades, necessitating evaluation of an appropriate population in order to establish optimal approaches for therapeutic treatment of the elderly and to develop a foundation for subsequent studies of the role of the cardiorespiratory system in the normal aging process. More studies of a longitudinal rather than cross-sectional nature are required before an adequate assessment of age-related alterations in function, capacity, or adaptative potential can be predicted.

Persistent myocardial ischemia following chronic hyperoxia in conscious dogs.

Following acute occlusion of the proximal left anterior descending (LAD) coronary artery, dogs were exposed continuously for 4 days in an environmental chamber to either 21% or 40% oxygen. Regional transmural myocardial blood flow was then determined by means of radioactive microspheres (8 to 10 microD) while each animal breathed room air (approximately equal to 21% oxygen). Blood flows in the anterolateral and apical regions of the left ventricle in normoxic animals (n = 5) averaged 0.95 +/- 0.03 and 0.69 +/- 0.13 ml/min X gm-1, respectively. In hyperoxic dogs (n = 5), blood flows in these regions were significantly lower, averaging 0.71 +/- 0.07 and 0.28 +/- 0.08 ml/min X gm-1, respectively in the anterolateral free wall, the greatest disparity in perfusion between experimental groups occurred in the subendocardial layers, and macroscopic evidence of necrosis was more widespread after hyperoxia.

Wandering atrial pacemaker associated with repetitive respiratory strain.

Electrocardiographic responses of body-builders and control subjects obtained during the performance of static and dynamic Valsalva maneuvers were studied to determine the causative stimulus for wandering pacemaker activity. The incidence of shifting or wandering pacemaker was nearly double in body-builders, suggesting that this is an occupational or activity-related arrhythmia. The causative mechanism is briefly discussed.

Reflex cardiac effects of local cutaneous cold exposure in dogs.

Cardiovascular responses initiated by local cutaneous cooling were evaluated in 16 anesthetized dogs of which 8 were pretreated with propranolol. Heart rate, cardiac index (CI), and indices of ventricular contractility were significantly elevated in untreated animals during cold stimulation. Myocardial oxygen uptake (MVo2) and left ventricular work (LVW) were also increased, and cardiac mechanical efficiency was significantly reduced. Total peripheral vascular resistance remained unchanged. In the propranolol group, heart rate decreased by 12 beats/min, but CI was maintained constant during cold by a rise in stroke index. Left ventricular dP/dtmax was reduced and ventricular preload elevated, but LVW, MVo2, and cardiac efficiency were unchanged. These data indicate that local cutaneous cooling increases myocardial oxygen demand by reflexly elevating heart rate and cardiac contractility rather than by increasing cardiac afterload. The response is completely eliminated by beta-adrenergic blockade. The significance of these observations in regard to the cold-intolerant individual with coronary disease is discussed.

Complications of jejunoileal bypass related to the excluded segment.

Dogs having a jejunoileal bypass, with the distal end of the bypassed segment being exteriorized as an ileal stoma, were compared with a control group having a Payne type jejunoileal bypass. In both groups, approximately 83 percent of the small intestine was bypassed. All except one dog survived the full six months of the study. During the first four months after the jejunoileal bypass, the dogs having an ileal stoma had more stable food consumption, less weight loss and higher levels of serum albumin than did those of the control group. During this period the bypassed segment in dogs of the control group usually contained bacteroides, whereas, after ileostomy, the segments were usually free of these organisms. At six months after jejunoileal bypass, there was no significant difference in the two groups with regard to nutrition, weight and the presence of bacteroides in the excluded segment. The hepatic structure and function was unaffected by both bypass procedures. Following a jejunoileal bypass in the dog, the complications associated with the excluded segment can be lessened by exteriorizing the distal end of the segment as a cutaneous ileal stoma.

Transcutaneous, noninvasive PO2 monitoring in adults during exercise and hypoxemia.

A new, commercially available, transcutaneous (tc) PO2 monitor was tested in adult females and in laboratory animals to assess its applicability in measuring arterial oxygen tension during physiological stress. Observed values on dogs correlated well with direct measurements of arterial PO2 and with previous data obtained from measurements of arterial blood during exercise and hypoxemia. In our female subjects the unit responded rapidly to changes in inspired ambient oxygen and electrical stability was excellent during maximal exercise tests. Transcutaneous PO2 decreased to an average of 87.8 Torr during maximum exercise breathing 20.9% O2, and to 32 Torr while breathing 12.6% O2 at maximum work. Two distinct patterns of response to tc PO2 were observed during hypoxic and normoxic exercise. The technique appears to have substantial future application both in clinical and physiological investigation involving adult subjects.

Blood volume and plasma constituent changes in splenectomized dogs consequent to exercise.

To assess the effects of submaximal exercise on fluid balance and blood constituents, changes in plasma volume, hematocrit, hemoglobin, plasma protein, serum osmolality, and serum electrolytes were measured in splenectomized dogs during treadmill work and recovery. During exercise approximating 32 and 50% of Vo2max, plasma volume did not significantly change. During recovery, plasma volume tended to increase by the same amount at both levels of exercise. Both total circulating plasma protein content and protein concentration increased during exercise. Serum osmolality increased abruptly during exercise and returned to the pre-exercise level immediately after cessation of work. Plasma volume changes calculated from both hematocrit and hemoglobin concentrations correlated well with direct measurements using labelled erythrocytes, but values calculated from hematocrit alone averaged 12% higher.

Effects of acute prolonged hypoxia on cardiovascular dynamics in dogs.

Intact anesthetized dogs were exposed for 75 min to either 5.75, 9.0, or 12.0% oxygen in nitrogen. Although pulmonary artery pressures were significantly elevated in all hypoxic exposures, systemic hypertension occurred only at the onset of severe hypoxia(5.75% O2). Coronary blood flow increased from an average of 130 during normoxia to a peak of 400 ml/100 g per min during inhalation of 5.75% O2, and coronary sinus oxygen tensions of 8 Torr and oxygen contents of 1.1 ml/100 ml were sustained for 75 min without biochemical, functional, or electrophysiological evidence of myocardial ischemia. Cardiac index (CI) increased significantly only during severe hypoxia (5.75% O2) with the greatest elevation after 30 min. Subsequently, CI decreased concomitantly with a 27% elevation in arterial hemoglobin concentration and oxygen-carrying capacity. It is concluded that the hypoxic threshold for significant elevations of cardiac output is between 6.0 and 9.0% O2.