Adel A. El-Etr

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 < 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 < 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 patients 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.

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.

Anticoagulation Following Placement of Epidural and Subarachnoid Catheters: An Evaluation of Neurologic Sequelae

&NA; 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.

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 H2O PEEP (IMV5PEEP) were studied in 20 patients after aortocoronary bypass surgery. Significant increases in cardiac index (CI) and stroke volume index (SI) (p < 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 IMVSPEEP, 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 < 0.01) with an associated significant decrease in mean arterial pressure (MAP), CI, SI (p < 0.01). When these patients were placed on IMV5PEEP, the hemodynamic variables returned to the values obtained during CMV. We conclude that changing from CMV to IMV has salutory effects on the patients 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 IMV5 PEEP.

Convulsions: An Unusual Response to Intravenous Fentanyl Administration

Intravenous fentanyl in doses of 100 to 150 pg/kg are today being used in cardiac anesthesia (1). The popularity of this technique has been due in part to stability of the cardiovascular system during induction of anesthesia and to suppression of stress responses to surgery (2, 3). The few complications associated with fentanyl-oxygen anesthesia include chest rigidity during induction of anesthesia (4,s) a n d awareness and recall of the intraoperative events (6) in the postoperative period. Recently we encountered five cases of generalized seizures during the rapid intravenous administration of fentanyl and we report two of these cases.

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 μg/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 hypo-perfusion. 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 < 0.0001) in groups II and IV than in groups I and III. Gastric fluid pH was significantly higher (P < 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.

Enflurane anesthesia for surgical removal of pheochromocytoma.

Four cases describing the use of enflurane as the main anesthetic during surgical removal of pheochromocytoma (PCC) are presented and the preoperative preparation and intraoperative management of the patients are discussed. Serum levels of epinephrine and norepinephrine were measured in 3 of the reported cases. Intraoperative values were extremely elevated during tumor manipulation, but there was only 1 minor episode of arrhythmias. Criteria for choosing anesthetic agents for surgical removal of PCC are outlined. The authors conclude from their experience and that of others that enflurane is as safe and effective an anesthetic as any now available for PCC excision.

The effect of ketamine upon norepinephrine and dopamine levels in rabbit brain parts

SummaryKetamine (40 mg/kg, i.v.) significantly increased dopamine levels in the thalamus and hypothalamus brain areas, but not in the midbrain or caudate nucleus. The increase in dopamine occurred during the time when ketamine produced its maximal anesthetic action (10–30 min). Ketamine had no effect upon norepinephrine levels in whole brain or the select brain parts with the exception of caudate nucleus at any of the times studied. These results demonstrate an effect of ketamine upon dopamine levels in those brain regions previously suggested as the site of ketamines anesthetic action.

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 thiopen-tone 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 μg/1. Conversely, there was a significant reduction in systemic vascular resistance index, 3388 to 2260, and plasma norepinephrine, 1.10 to 0.88 μg//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 < 0.05). This study demonstrates significant catecholamine responses during isoflurane anaesthesia. The increase in plasma epinephrine paralleled 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.RésuméLes modifications hémodynamiques ainsi que celles des catécholamines plasmatiques survenant au cours d’anesthésies à l’isoflurane ont été évaluées chez dix patients soumis à des pontages aorto-coronariens. L’induction de Fanesthésie a été effectuée au thiopental et le maintien à l’isoflurane à une concentration de 1.5 à 2 pour cent. Après dix minutes d’anesthésie à l’isoflurane, on observait une augmentation significative de la fréquence cardiaque qui passait de 68 à 80/minute, du débit cardiaque qui passait de 3.75 à 4.6 μg/l, et de I’épinéphrine plasmatique qui passait de 0.80 à 1.33 (xg/1; concouramment, survenait une diminution significative de l’index de résistance vasculaire systémique qui passait de 3388 à 2260 dynes.sec. cm-5.m2, et de la norépinéphrine qui s’abaissait à 0.088 μg/1 en comparaison d’un taux de 1.1 μ.g/1 au départ.Vingt-cinq minutes plus tard, (après la sternotomie) la fréquence, le débit cardiaque et le taux plasmatique d’épinéphrine étaient encore élevés alors que l’index de résistance vasculaire périphćrique et le taux plasmatique de norépinéphrine demeuraient abaissés (p< 0.05). Cette étude démontre la présence d’une réponse significative des catécholamines au cours de I’anesthésie é l’isoflurance. L’élévation de l’épinéphrine plasmatique était parrallèle à l’augmentation de la fréquence et du débit cardiaque alors que la diminution du taux de la norépinéphrine coincidait avec la chute de la résistance vasculaire périphérique. A partir de ces résultats, nous concluons que les modifications des catécholamines contribuent à la production des modifications cardiaques et vasculaires périphériques observées au cours des anesthésies à l’isoflurane.