Qualitative evaluation of coronary flow during anesthetic induction using thallium-201 perfusion scans.

Qualitative distribution of coronary flow using thallium-201 perfusion scans immediately postintubation was studied in 22 patients scheduled for elective coronary artery bypass surgery. Ten patients received a thiopental (4 mg/kg) and halothane induction. Twelve patients received a fentanyl (100 micrograms/kg) induction. Baseline thallium-201 perfusion scans were performed 24 h prior to surgery. These scans were compared with the scans performed postintubation. A thallium-positive scan was accepted as evidence of relative hypoperfusion. Baseline hemodynamic and ECG data were obtained prior to induction of anesthesia. These data were compared with the data obtained postintubation. Ten patients developed postintubation thallium-perfusion scan defects (thallium-positive scan), even though there was no statistical difference between their baseline hemodynamics and hemodynamics at the time of intubation. There was no difference in the incidence of thallium-positive scans between those patients anesthetized by fentanyl and those patients anesthetized with thiopental-halothane. The authors conclude that relative hypoperfusion, and possibly ischemia, occurred in 45% of patients studied, despite stable hemodynamics, and that the incidence of these events was the same with two different anesthetic techniques.

Metoclopramide and cimetidine to reduce gastric fluid pH and volume.

Eighty female patients undergoing outpatient laparoscopy were divided into four equal groups to investigate the effect of cimetidine and metoclopramide on the gastric fluid volume and pH. Group I patients received two placebo tablets. Group II patients were given metoclopramide, 10 mg, and one placebo tablet. Group III patients received cimetidine, 300 mg, and one placebo tablet. Group IV patients received metoclopramide, 10 mg, and cimetidine, 300 mg. Gastric fluid volume in group I patients was 83.9 +/- 2.3 ml; in group II patients, 11.1 +/- 0.63 ml; in group III patients, 51 +/- 2.33 ml; and in group IV patients, 12.05 +/- 0.79 ml. Gastric fluid pH was 1.38 +/- 0.12, 2.6 +/- 0.21, 4.04 +/- 0.32, and 4.64 +/- 0.28 in groups I through IV, respectively. Gastric fluid volume was significantly less (P less than 0.0001) in groups II and IV than in groups I and III. Gastric fluid pH was significantly higher (P less than 0.0001) in groups III and IV than in groups I and II. It is concluded that administration of metoclopramide and cimetidine two hours prior to induction of anesthesia significantly decreases the gastric fluid volume and increases gastric fluid pH, thereby decreasing both the likelihood of aspiration of gastric contents and the likelihood of severe pulmonary reaction, should aspiration occur.

A review of pulmonary artery catheterization in 6,245 patients.

From July 1977 to December 1982, 6,245 patients requiring cardiac and noncardiac operations had pulmonary artery (PA) catheterizations for perioperative monitoring. Their ages ranged from 4 to 94 years. PA catheters were inserted through the external or internal jugular vein in 6,146 patients, while arm veins were used in 99 patients. Complications included persistent PVCs requiring therapy in 193 (3.1%), right bundle branch blocks in three (0.048%), left bundle branch and complete heart block each in one patient (0.016%), intrapulmonary hemorrhage in four (0.064%), minor pulmonary infarcts in four (0.064%), perforation of right ventricle in one (0.016%), and death from uncontrollable pulmonary hemorrhage in one patient (0.016%). This investigation reveals a low incidence of morbidity associated with PA catheterization.

Reinfarction following anesthesia in patients with myocardial infarction.

The authors studied the incidence of and factors related to recurrent perioperative myocardial infarction retrospectively during 1973-1976 (Group 1) and prospectively during 1977-1982 (Group 2). Reinfarction occurred in 28 of 364 (7.7%) patients in Group 1 and 14 of 733 (1.9%) in Group 2 (P less than 0.005). When the previous infarction was 0-3 and 4-6 months old, perioperative reinfarction occurred in 36% and 26% of Group 1 patients, respectively, and only 5.7% and 2.3% of Group 2 patients, respectively, (P less than 0.05). In both groups, patients with associated congestive heart failure had a higher reinfarction rate. Patients who had intraoperative hypertension and tachycardia or hypotension develop had a higher incidence of reinfarction in both groups. The results suggest that preoperative optimization of the patient's status, aggressive invasive monitoring of the hemodynamic status, and prompt treatment of any hemodynamic aberration may be associated with decreased perioperative morbidity and mortality in patients with previous myocardial infarction. Which of these factors, if any, contributed to the improved outcome was not determined in this study.

Increased heparin requirements with autotransfusion.

This study shows that heparin requirements are increased by withdrawing heparinized autologous blood before bypass for later autotransfusion.

Haemodynamic and catecholamine response to isoflurane anaesthesia in patients undergoing coronary artery surgery.

Haemodynamic and plasma catecholamine responses were evaluated during isoflurane anaesthesia in ten patients undergoing coronary artery bypass surgery. Following thiopentone induction the patients were anaesthetized with isoflurane 1.5-2.0 per cent in oxygen. The results show that after 10 minutes of isoflurane anaesthesia there was a significant increase from baseline in heart rate, 68 to 80; cardiac output, 3.75 to 4.61; and plasma epinephrine, 0.80 to 1.33 microgram/l. Conversely, there was a significant reduction in systemic vascular resistance index, 3388 to 2260, and plasma norepinephrine, 1.10 to 0.88 microgram/l. Twenty-five minutes later, after sternotomy, heart rate, cardiac output and the level of plasma epinephrine were still elevated, and systemic vascular resistance index and plasma norepinephrine remained lowered (p less than 0.05). This study demonstrates significant catecholamine responses during isoflurane anaesthesia. The increase in plasma epinephrine parallelled the increase in heart rate and cardiac output, and the decrease in plasma norepinephrine paralleled the decrease in systemic vascular resistance. Based upon these findings we conclude that catecholamine responses contribute to the cardiac and peripheral cardiovascular changes observed with isoflurane anesthesia.

Epidural triamcinolone and adrenal response to hypoglycemic stress in dogs.

The effect of an epidural steroid injection (triamcinolone) on plasma cortisol levels was studied in twelve beagle dogs following an insulin-induced hypoglycemic stress. The control group (n = 6) received epidural bupivacaine only. This group consistently increases their plasma cortisol values in response to the hypoglycemic stress induced by 0.6 units of insulin/kg administered intravenously. Dogs in the study group (n = 6) received epidural bupivacaine plus 2 mg/kg of triamcinolone. This group was unable to increase their plasma cortisol values in response to similar insulin-induced hypoglycemic stress for four weeks. Return to normal function occurred five weeks following epidural triamcinolone. The authors hypothesize that the inability of the dogs to respond to hypoglycemic stress by increasing their plasma cortisol may interfere with homeostasis and decrease their tolerance to other types of stress up to 4 weeks following epidural triamcinolone administration.

Hemodynamic response to changes in ventilatory patterns in patients with normal and poor left ventricular reserve.

Hemodynamic effects of controlled mechanical ventilation (CMV), intermittent mandatory ventilation (IMV), and intermittent mandatory ventilation with 5 cm H20 PEEP (IMV 5 peep) were studied in 20 patients after aortocoronary bypass surgery. Significant increases in cardiac index (CI) and stroke volume index (SI) (p less than 0.01) resulted in patients with normal left ventricular end-diastolic pressure (LVEDP) and ejection fraction (EF) changing from CMV to IMV. With a change from IMV to IMV 5 peep, the CI and SI returned to CMV values. However, in patients with increased LVEDP with an EF of less than 0.6, suggesting poor ventricular function and reserve, when the mode of ventilation was changed from CMV to IMV, right atrial pressure (RAP) and pulmonary artery occlusion pressure (PAOP) significantly increased (p less than 0.01) with an associated significant decrease in mean arterial pressure (MAP), CI, SI (p less than 0.01). When these patients were placed on IMV 5 peep, the hemodynamic variables returned to the values obtained during CMV. We conclude that changing from CMV to IMV has salutory effects on the patient's hemodynamic values with normal left ventricular function. But in patients with failing left ventricle, volume overload of right ventricle which occurs with the institution of spontaneous respiration during IMV has deleterious effects on the hemodynamic variables. These deleterious effects can be effectively negated by the application of IMV 5 peep.

Anticoagulation following placement of epidural and subarachnoid catheters: an evaluation of neurologic sequelae.

The incidence of neurologic complications arising from anticoagulant therapy, following epidural and subarachnoid catheterization in 3,164 and 847 patients, respectively, was determined. Twenty patients experienced minor neurologic complications or low back pain which was self-limiting and resolved with time. There was no incidence of peridural hematoma leading to spinal cord compression. This investigation shows that the occurrence of symptomatic hematomas following anticoagulation in patients with epidural or subarachnoid catheters is a very rare complication, assuming proper patient selection, an atraumatic technique, and appropriate monitoring of anticoagulant activity.

Effect of priming volume on serum catecholamines during cardiopulmonary bypass.

Several theories have been proposed to explain the transient hypotension which occurs upon the initiation of cardiopulmonary bypass. The present study investigated the possibility that addition of the lactated Ringer's solution pump priming volume to the circulation causes dilution of circulating catecholamines leading to the hypotension. Circulating epinephrine and norepinephrine levels were measured during cardiopulmonary bypass in patients anaesthetized with halothane. The results demonstrate dilution of circulating catecholamines at the start of bypass in conjunction with the observed hypotension. During the bypass period, mean blood pressure graudally recovered to normotensive levels even though circulating catecholamine levels remained significantly lowered, indicating a mechanism for the recovery of blood press which is not sympathoadrenal. The results obtained from this study demonstrate a temporal relationship between catecholamine dilution by the pump priming volume and the observed hypotension. Whether catecholamine dilution is the sole factor causing the hypotension remains to be determined.

Nitroglycerin and the neuromuscular blockade produced by gallamine, succinylcholine, d-tubocurarine, and pancuronium.

The finding in cats of prolonged pancuronium neuromuscular blockade in conjunction with intravenous infusion of nitroglycerin was previously reported by this laboratory. To expand on this finding the present study compared the effects of nitroglycerin on neuromuscular blockade produced by gallamine, d-tubocurarine, succinylcholine, and pancuronium, and further characterized the nitroglycerin-pancuronium interaction. The results indicate that of the relaxants studied only pancuronium neuromuscular blockade is prolonged, and that the prolongation is not due to altered plasma elimination of pancuronium. In vitro pancuronium blockade was not affected by nitroglycerin, suggesting the involvement of a metabolite in the block prolongation response. Reversibility of the prolonged pancuronium block by neostigmine is not influenced by nitroglycerin.

Prolongation of pancuronium-induced neuromuscular blockade by intravenous infusion of nitroglycerin.

Based upon clinical observation of undue prolongation of pancuronium-induced blockade in the presence of intravenous infusion of nitroglycerin, neuromuscular blockades produced by pancuronium, succinylcholine and d-tubocurarine were studied in 51 cats using the sciatic-gastrocnemius nerve-muscle preparation. Pancuronium-induced blockade was found to be significantly prolonged (P less than 0.1) in the presence of a nitroglycerin infusion of 1 microgram/kg/min (65 vs. 127 min). Less, but still significant, prolongation occurred when nitroglycerin, 0.5 microgram/kg/min, was infused. The intravenous infusion of nitroglycerin must be started prior to the pancuronium injection for the block to be prolonged. Neuromuscular blocks produced by succinylcholine and d-tubocurarine were not altered by nitroglycerin. In experiments using the isolated rat diaphragm preparation, the depth of pancuronium-induced block was found not to be changed by nitroglycerin, suggesting an effect of nitroglycerin on the process of recovery from blockade. These findings indicate a selective pancuronium-nitroglycerin interaction.

Serum epinephrine and norepinephrine during valve replacement and aorta-coronary bypass.

A comparison of the levels of serum epinephrine, norepinephrine and blood pressure was made in 25 patients undergoing aorta-coronary bypass or valve replacement who were anaesthetized with a nitrous oxide-narcotic technique. Serum epinephrine and norepinephrine were measured in arterial samples drawn pre-induction, post-induction, before cardiopulmonary bypass, two and eight minutes after initiation of cardiopulmonary bypass, 20 minutes before termination and after termination of cardiopulmonary bypass. In both patient groups significant increases in epinephrine and norepinephrine occurred befored cardiopulmonary bypass, with accompanying increase of blood pressure in the valve replacement patients. During cardiopulmonary bypass an initial hypotensive response (p less than 0.001) was recorded, followed by a significant increase in blood pressure and epinephrine in both groups. After cardiopulmonary bypass, aorta-coronary bypass patients had epinephrine, norepinephrine and blood pressure equal to levels before cardiopulmonary bypass. In contrast, serum epinephrine continued to rise in the valve replacement patients, with a gradual recovery of blood pressure to pre-bypass levels. These findings demonstrate significant differences in blood pressure and catecholamine response in patients with valvular disease from patients with coronary artery disease.