Biomedical subjects
Publications and source records attributed to W A Lell.
IMPLICATIONS: Hereditary angioedema is a disease associated with acute complement-mediated inflammation and swelling of the airway and other vital organs. This case describes the impact of hereditary angioedema and cardiopulmonary bypass on hemostasis as assessed by thrombelastography.
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The use of etomidate for induction of anesthesia in patients requiring urgent coronary artery surgery provides good cardiovascular stability. However, long-term etomidate infusions may cause transient signs of adrenocortical suppression. The purpose of this study was to determine whether an induction bolus dose of etomidate would cause clinically relevant endocrine dysfunction in urgent coronary artery bypass patients. With institutional review board approval, 11 patients were prospectively randomized to a diazepam (control) or etomidate rapid sequence induction. The diazepam group (n=6; mean, 69 years) received 0.4 mg/kg of diazepam. The etomidate group (n=5; mean, 54 years) received 0.3 mg/kg of etomidate. Maintenance anesthesia included nitrous oxide, oxygen, pancuronium, and fentanyl in increments up to 32 microg/kg. Hemodynamics, cortisol, epinephrine, and norepinephrine were measured both intraoperatively and postoperatively. The only significant difference between the two groups in hemodynamic parameters was a higher heart rate in the etomidate group. Both agents adequately controlled the stress response to intubation as judged from the levels of epinephrine, norepinephrine. and cortisol. However, in both groups epinephrine and norepinephrine increased between intubation and removal of the aortic cross-clamp. Cortisol also increased from the time of cross-clamp removal to 12 and 24 hours post-bypass. During anesthesia and surgery in the pre-bypass period, there was a decrease in cortisol over time in the etomidate group, and there was an increase with diazepam. Thus, etomidate provided stable hemodynamics, possible mild intraoperative adrenocortical suppression, a depressed hormonal stress response to intubation, and a normal hormonal reaction to the later part of surgery and the postoperative period.
We studied the cardiovascular effects of esmolol, a newly synthesized beta-adrenocepter antagonist, in anesthetized humans. Forty patients (four groups of 10 each) with ischemic heart disease and normal ventricular function were anesthetized with diazepam, pancuronium, and N2O in O2. Esmolol was given by continuous infusion in cumulative doses of 1100 micrograms/kg (group 1), 2000 micrograms/kg (group 2), and 2700 micrograms/kg (group 3); a control group received no esmolol. Infusion of esmolol was begun 3 min prior to and ended 4 min after tracheal intubation. All three doses of esmolol significantly (P less than 0.001) attenuated the heart rate responses to intubation. Rate-pressure products were significantly (P less than 0.001) lower in esmolol-treated patients than in controls after intubation, but ST-segment changes compatible with ischemia occurred in one patient in each group. Increases in heart rate were associated with significant increases in plasma norepinephrine levels (r = 0.45, P = 0.02) in the control group, but not in esmolol-treated patients, a demonstration that esmolol antagonizes the beta-adrenergic effects of norepinephrine. The effect of esmolol on heart rate was absent 5 min after cessation of infusion, and plasma levels of esmolol were undetectable in 26 of 30 treated patients 15 min after the termination of esmolol infusion. Esmolol has a rapid onset and short duration of effect. It can be used safely during anesthesia in patients with normal ventricular function to attenuate cardiac response to sympathetic stimulation.
Over the past six years there has been a 15-fold increase in the number of patients requiring reoperation coronary artery bypass grafting (RCABG) surgery at the University of Alabama in Birmingham. To determine the perioperative risk, a retrospective chart survey of one calendar year's (1981) experience was made comparing the 58 RCABG patients with 59 cohorts undergoing primary operation. All patients were anaesthetized with diazepam, fentanyl and halothane or enflurane anaesthesia. Preoperative evaluation revealed by history that the incidence of unstable angina and digoxin use were greater (p = 0.05) in the RCABG patients. Cardiac catheterization revealed a higher incidence (26 vs 89 percent) of left main coronary disease in controls and similar indices of left ventricular function (wall abnormalities, ejection fraction and LVEDP). Operating and bypass times were longer (p less than 0.01) for RCABG patients and there was a trend for greater (p = 0.08) use of dopamine in the RCABG patients. CK-MB release was significantly (p less than 0.05) greater in RCABG patients. Serious postoperative complications (CK-MB greater than or equal to 15 IU/L, low cardiac output, and death) were significantly (p = 0.02) greater in the RCABG group. It is concluded that RCABG patients represent a greater risk of complications and that new strategies for improving myocardial protection need to be developed to reduce the risk.
Hydroxyethyl starch or hetastarch (HES), a synthetic colloid for intravascular volume expansion, was compared with albumin after coronary artery operations in 30 patients (15 in each study group). Cardiac index, atrial pressures, heart rate, and systolic blood pressure were similar in both groups. There were no differences in cumulative urine output at 24 hours or in weight change during the first 7 postoperative days. Values for colloid osmotic pressure, as well as for this variable minus left atrial pressure, were lowest soon after bypass but returned to baseline within 4 hours, with no difference between groups in the first 24 hours or 7 days after operation. Coagulation variables were similar, but prothrombin and partial thromboplastin times were higher 12 hours postoperatively and fibrinogen level was lower 7 days postoperatively in the patients receiving HES. There was no clinical evidence of excessive bleeding, although cumulative chest drainage at 12 and 24 hours was slightly higher in the HES group (p = 0.09 and 0.08, respectively). We conclude that hetastarch is a safe and effective colloid to use following coronary operations.
The authors reviewed their experience with combined aortic valve replacement and coronary artery bypass grafting using a standardized cold cardioplegic technique for intraoperative myocardial protection in 54 consecutive patients during a 5-year interval ending in May 1982. Calcific aortic stenosis was the most common indication for aortic valve replacement. Thirty-seven patients (69%) had greater than 50-60% stenoses in at least two of the three major coronary arterial systems. No patient with combined aortic valvular and coronary artery disease had only valve replacement during the study interval, and no patient was refused operation. The mean number of arteries grafted was 2.4. There was one hospital death (1.9%), and one patient (1.9%) had electrocardiographic evidence for perioperative myocardial infarction. One additional patient required postoperative intra-aortic balloon pumping. There have been four late deaths in the followup period extending to 65 months. Survival at 3 years for the entire group was 87%, for the patients with aortic stenosis was 95%, and for the patients with aortic regurgitation or mixed lesions was 65%. There were no cardiac-related deaths among the patients with aortic stenosis and one non-fatal myocardial infarction in the follow-up period. The results with this technique of intraoperative myocardial protection are superior to those reported with previously employed methods (coronary perfusion, hypothermic ischemic arrest) and indicate that coronary artery bypass grafting should be performed in all patients with coexisting aortic valvular and coronary artery disease who require valve replacement. A substantial benefit (increased survival, decreased late myocardial infarction) may exist for the subgroup of patients with aortic stenosis.
Labeled microspheres, 15 microns in diameter, were used to determine cardiac output and regional blood flow response to cross-clamping of the midthoracic aorta and subsequent sodium nitroprusside (SNP) infusion in 11 dogs. During aortic cross-clamping, mean arterial pressure above the occlusion (MAPa) increased 30% to 35%, mean arterial pressure below the occlusion (MAPb) decreased 87%, cardiac index decreased 12% to 14%, left atrial pressure (LAP) doubled, and renal and spinal cord (lower part) blood flows decreased substantially (85% to 94%). SNP infusion returned MAPa to baseline values, decreased MAPb by half, and substantially and further decreased renal blood flow (to 3% to 5% of baseline values). Myocardial and cerebral blood flows increased substantially (up to 250% to 400%). An increase in preload (fluid load) was accompanied by an increase in LAP, cardiac index, and myocardial blood flow only but not in renal or spinal cord flow. There was a strong association between cortical renal blood flow and MAPb (r2 = 0.92; p less than 0.0001), which suggests that blood flow through organs and tissues below the occlusion is pressure dependent. The data show that SNP infusion during thoracic aortic cross-clamping improves systemic and regional circulation above the occlusion but decreases MAPb and therefore blood flow below the occlusion. SNP infusion should be used with caution during aortic cross-clamping, since arterial hypotension of any degree may be deleterious to organs below the cross-clamp.
Fifty patients undergoing isolated coronary artery bypass grafting procedures using a clear, cold cardioplegic solution, topical hypothermia, and reduced systemic flow for intraoperative myocardial protection were evaluated for myocardial injury by serial plasma creatine kinase-MB isoenzyme (CK-MB) measurements and electrocardiograms. Forty-one (82%) of the patients had three-vessel disease. Preoperative left ventricular contractility determined angiographically was normal in 13 patients (26%), mildly abnormal in 26 (52%), and moderately or severely abnormal in 11 (22%). The number of arteries grafted ranged from 2 to 6 (mean, 3.5). The mean duration of aortic clamping was 38.6 +/- 1.6 minutes. There were no hospital deaths. Enzymatic and electrocardiographic (ECG) evidence of myocardial infarction occurred in 1 patient. Nonspecific ECG changes occurred in 16 patients (32%), and th electrocardiograms were unchanged in the remaining 33 patients (66%). In the 49 patients without ECG evidence of infarction, the mean peak plasma CK-MB value, which occurred 6 hours after the onset of cardiopulmonary bypass, was 7.9 +/- 0.8 IU/L (standard error of the mean) and the mean integrated area 158 +/- 19.5 IU/L X hours. There was no correlation between these CK-MB values and the extent of disease, number of arteries grafted, or the duration of myocardial ischemia. These data document a low incidence of perioperative myocardial injury with this technique, and can serve as a baseline for comparison with other techniques for intraoperative myocardial protection in this setting.
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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.
One hundred four consecutive patients undergoing open heart surgery were studied to determine the duration of intubation and ICU stay associated with an anesthetic management protocol designed to avoid prolonged postoperative respiratory depression. The results document the feasibility and safety of early extubation and shortened ICU stay in patients having operations for ischemic and acquired valvular heart disease. Patients with complex congenital heart defects require significantly longer periods of respiratory support and intensive care.
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