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Query: UMLS:C0278134 (anesthesia)
 110,339 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Elevated catecholamines and beta-adrenergic receptor hyporesponsiveness (or desensitization) have been demonstrated in failing human myocardium, but the role of the alpha-adrenergic receptor remains unclear. The authors tested the hypothesis that alpha 1-adrenergic responsiveness decreases in patients with impaired ventricular function undergoing coronary artery revascularization. Impaired ventricular function was defined prospectively by left ventricular ejection fraction less than or equal to 40% (group I, n = 12), and normal ventricular function by ejection fraction greater than 40% (group II, n = 22). Phenylephrine (Phe) pressor dose-response curves were established prior to anesthesia, during fentanyl anesthesia, and during fentanyl anesthesia plus hypothermic cardiopulmonary bypass at the time of aortic cross-clamp (anes + CPB/AXC). Polynomial regression of the Phe dose response curve estimated the Phe dose required to increase mean arterial blood pressure 20%, designated PD20. Although pre-anesthesia PD20 and anes + CPB/AXC PD20 values were not affected by ejection fraction, significant differences in PD20 (P less than 0.05) between groups occurred during fentanyl anesthesia (group I = 2.28 +/- 1.60 micrograms.kg-1, group II 1.57 +/- 0.98 micrograms.kg-1; mean +/- SD). Anes + CPB/AXC was associated with a significant reduction in PD20 in both groups compared with pre-anesthesia (P less than 0.01). Our results suggest impairment of alpha 1-adrenergic responsiveness occurs during fentanyl anesthesia in patients with ejection fractions less than or equal to 40% (evidenced by greater PD20 values). Although this impairment may be due to altered Phe pharmacokinetics, these results also support the possible existance of alpha 1-adrenergic receptor desensitization in this group. Reduction in PD20 during anes + CPB/AXC in all patients points to more powerful effects than fentanyl anesthesia alone; such influencing effects may include hemodilution, hypothermia, elevated plasma catecholamines, exclusion of the pulmonary circulation, or altered Phe pharmacokinetics.
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PMID:alpha 1-Adrenergic responsiveness during coronary artery bypass surgery: effect of preoperative ejection fraction. 284 91

This study was undertaken to assess the effects of propofol (versus enflurane, fentanyl, and thiopental) on hemodynamic stability and recovery characteristics when used for maintenance of anesthesia during elective coronary artery bypass grafting (CABG) procedures. Ninety premedicated patients scheduled for elective coronary revascularization had anesthesia induced with fentanyl 25 micrograms/kg intravenously (i.v.). When the mean arterial blood pressure (MAP) increased 10% above preoperative baseline values, patients were randomized to receive one of four anesthetic treatments: enflurane, 0.25-2.0%; fentanyl, 10-20 micrograms/kg i.v. bolus doses; propofol, 50-250 micrograms.kg-1.min-1 i.v.; or thiopental, 100-750 micrograms.kg-1.min-1 i.v.. The maintenance anesthesia was titrated to achieve hemodynamic stability (i.e., maintain the MAP within 10% of the baseline values and heart rate [HR] within 20% of the baseline values). After bypass, anesthetic and cardiovascular drugs were titrated to maintain the MAP > 65 mm Hg and the cardiac index (CI) > 2.3 L.min-1.m-2. Recovery was assessed by noting the times at which patients first opened their eyes, responded to verbal communication, correctly responded to specific commands, underwent tracheal extubation, and were discharged from the intensive care unit (ICU). Although less intraoperative hypertension was noted in the propofol-treated patients (19 +/- 11 min vs 38 +/- 26 min, 30 +/- 24 min, and 30 +/- 23 min in the enflurane, fentanyl, and thiopental groups, respectively) (P = 0.04), the incidence of hypotension did not differ significantly among the groups. Vasopressor drugs were required more often during the prebypass period in fentanyl and propofol patients (4/22 and 5/23, respectively) compared to the thiopental group (0/21) (P < 0.05). During CPB, fentanyl-treated patients required vasoconstrictors more often than patients in the other three treatment groups (14/22 vs 6/24, 4/23, and 5/21 in the enflurane, propofol, and thiopental groups, respectively) (P < 0.01). Although fentanyl-treated patients had significantly greater requirements for inotropic support during weaning from CPB than propofol-treated patients (14/22 vs 7/23) (P < 0.038), there were no significant differences among the groups in the postbypass or ICU periods. Propofol-treated patients responded to verbal stimuli (2.1 +/- 1.3h vs 4.0 +/- 3.5h, 4.7 +/- 2.7h, and 5.6 +/- 3.6h in the enflurane, fentanyl, and thiopental groups, respectively) (P = 0.01) and followed commands earlier (propofol 7.3 +/- 5.2h vs enflurane 12.5 +/- 5.7h, fentanyl 13.1 +/- 6.6h, and thiopental 12.8 +/- 6.7 h) (P = 0.01).(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:The effects of anesthetic technique on the hemodynamic response and recovery profile in coronary revascularization patients. 748 74

CPB produces changes in the blood-gas partition coefficient dependent on the prime used and temperature. Fortunately, the overall effect for hypothermic CPB and a crystalloid prime is only +2%. A volatile agent started during hypothermic CPB takes longer to equilibrate and agents already in use need to re-equilibrate, potentially changing the depth of anaesthesia, until equilibration is complete. As these agents are metabolized to a small degree and washout is fast, the duration of action is not prolonged after CPB.
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PMID:Pharmacokinetics of analgesics, sedatives and anaesthetic agents during cardiopulmonary bypass. 754 56

A 73-year-old female patient was admitted for myocardial infarction. Conventional treatment with heparin was started, intraaortic balloon assistance was required for several days, together with heparin. The platelet counts decreased progressively, from 288 G.l-1 on admission to 41 G.l-1 on the 16th day, despite the use of low molecular weight heparin. The in vitro heparin platelet aggregation test remained positive. This aggregation ended on adding iloprost, an analogue of prostacyclin, to the platelet culture bath. A coronary aortic bypass graft was required. An infusion of iloprost was started just after induction of anaesthesia. The initial dose of 0.5 ng.kg-1 x min-1 was gradually increased to 20 ng.kg-1 x min-1. Heparin (400 IU.kg-1) was thereafter added. To maintain a mean blood pressure of a least 50 mmHg, an infusion of up to 10 micrograms.kg-1 x min-1 of phenylephrine was given. As it was insufficient, an infusion of up to 1 microgram.kg-1 x min-1 noradrenaline was required. The iloprost infusion was gradually stopped 15 min before the end of CPB, together with that of noradrenaline. Platelet aggregation tests were positive after protamine had been given, whereas they had been negative during the infusion of iloprost. There was no abnormal postoperative bleeding. An infusion of 2 ng.kg-1 x min-1 was started at the sixth postoperative hour for 48 h, until the coumarin-like agent had started taking its effects. It is concluded that iloprost might be useful for carrying out cardiac surgery in patients with heparin-induced thrombocytopaenia.
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PMID:[Iloprost (Ilomedine) and extracorporeal circulation with conventional heparinization in a patient with heparin-induced thrombocytopenia]. 768 35

Twenty-four patients undergoing elective coronary artery bypass surgery were studied. Either the angiotensin-converting enzyme (ACE) inhibitor enalaprilat, 0.06 mg/kg, (n = 12), or saline solution (= control group; n = 12), was randomly and blindly administered intravenously when the mean arterial blood pressure (MAP) increased to 90 mmHg after induction of anesthesia. Cardiorespiratory parameters were studied before injection, during the subsequent 30 minutes, precardiopulmonary bypass (CPB), post-CPB, and at the end of surgery. MAP was significantly reduced 5 minutes after administration of enalaprilat. The peak reduction of blood pressure was observed after 30 minutes (from 98 +/- 4 to 68 +/- 8 mmHg). Even immediately before CPB (112 +/- 12 minutes after injection of enalaprilat), MAP and systemic vascular resistance were significantly lower than baseline values. Heart rate remained almost unchanged in both groups. Cardiac index increased slightly in the enalaprilat patients (maximum: +0.75 L/min/m2 20 minutes after injection). Filling pressures (central venous pressure, pulmonary capillary wedge pressure) were also significantly reduced by enalaprilat. There were no differences from the control patients with regard to changes in right ventricular hemodynamics (right ventricular ejection fraction, right ventricular end-diastolic volume, right ventricular end-systolic volume), pulmonary gas exchange (PaO2), or intrapulmonary right-to-left shunting (Qs/Qt). VO2 increased only in the enalaprilat patients (from 179 +/- 28 to 230 +/- 30 mL/min) (p < 0.05). Cardiorespiratory parameters did not differ between the two groups post-CPB.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cardiorespiratory response of intravenous angiotensin-converting enzyme inhibitor enalaprilat in hypertensive cardiac surgery patients. 771 54

Metabolic responses during recovery from cardiac operations for various congenital heart defects were studied in 30 mechanically ventilated pediatric patients in two groups: infants 1 year or less (group I) and children more than 1 year old (group II). Oxygen consumption (VO2) and carbon dioxide production (VCO2) were measured using a pediatric metabolic monitor intermittently after induction of anesthesia, after skin closure, 2 to 4 hours postoperatively, and on the first postoperative morning in the pediatric intensive care unit. Energy expenditure and respiratory quotient were determined from respiratory gas measurements. Rectal and skin temperatures and hemodynamic variables were recorded at the same time. VO2 increased during rewarming 2 to 4 hours after the operation by 12 +/- 15% in group I and by 24 +/- 19% in group II, while rectal temperature increased by 2.0 +/- 1.2 degrees C and 1.8 +/- 1.4 degrees C, respectively. No further increase in VO2 occurred until the first postoperative morning. A hypermetabolic response was not seen in all cases despite marked thermal changes. High-dose fentanyl anesthesia partly explains the low responses. On the other hand, low cardiac output may also compromise oxygen supply. Sixty-three percent of infants were treated for cardiac failure before surgery and 75% needed inotropic support immediately after the operation. Low central venous oxyhemoglobin saturation values (ScvO2 < 60%) were observed during rewarming, indicating an increase in oxygen extraction secondary to an increased oxygen demand in the brain during recovery from anesthesia, and a low cardiac output or delayed restoration of cerebral blood flow after CPB and deep hypothermia.
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PMID:Oxygen consumption following pediatric cardiac surgery. 788 Sep 92

Total intravenous anesthesia (TIVA) using alfentanil and propofol was used in 10 patients undergoing coronary artery bypass grafting. In an attempt to diminish unwanted side effects, lower doses were chosen than if either drug had been used alone. Anesthesia was induced with alfentanil, 75 micrograms/kg, followed by a sleep dose of propofol (mean dose 0.5 mg/kg). Maintenance in the precardiopulmonary bypass (CPB) period was achieved by infusions of propofol (6 mg/kg/h) and alfentanil (100 micrograms/kg/h). These were decreased by two thirds on commencement of CPB, and increased to half the initial rate on rewarming to 32 degrees C. Additional boluses of alfentanil were used to control breakthrough hypertension. The mean arterial pressure (MAP) and left ventricular stroke work index (LVSWI) fell significantly on induction. MAP but not LVSWI returned to baseline levels at skin incision. The cardiac index (CI) was maintained. A degree of myocardial depression was suggested by a fall in LVSWI despite maintaining preload, and by the failure of CI to increase in the presence of a reduced SVR. Anesthesia was satisfactory in all but one patient who developed breakthrough hypertension on sternotomy with transient ST segment depression, and awareness after CPB despite a plasma alfentanil concentration of 450 ng/mL. Mean time to wakening was 55 minutes. The study indicated that TIVA using propofol and alfentanil in the dosages described provides satisfactory basal anesthesia for coronary artery bypass surgery in patients with good left ventricular function, but requires additional pharmacologic manipulation, particularly with boluses of alfentanil, to control breakthrough hypertension.
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PMID:Total intravenous anesthesia using propofol and alfentanil for coronary artery bypass surgery. 806 Dec 61

The authors examined the effects of clonidine, a preferential alpha-adrenergic agonist, upon myocardial oxygen balance and pulmonary function during the perioperative period in patients undergoing CABG surgery. Anesthesia was provided by fentanyl infusion reaching the final dose of 100 micrograms.kg.min-1 in 10 minutes before skin incision. Ten patients received clonidine 0.125 mg intravenously after induction of anesthesia; a group of 10 patients was managed identically except for nitroglycerin infusion during the pre-CPB period, in order to keep the aortic pressure in the normal range. Intergroup differences in hemodynamics, respiratory data, rewarming time, post-operative ST-tract pattern and enzyme values were evaluated. Results are suggestive (in the clonidine group) for ameliorating myocardial oxygen balance by reducing oxygen consumption indexes (systolic aortic pressure, cardiac index, rate pressure product) and increasing coronary blood flow [coronary perfusion pressure (p < 0.01)] at the end of the surgery and intensive care. Global oxygen consumption reduction, recorded in the clonidine group patients, the oxygen available being unchanged, ameliorated the total oxygen balance mainly after sternotomy (p < 0.05) and at the end of bypass (p < 0.05). Cardiac index was greater during the awakening and rewarming period in intensive care and the ventilatory/perfusion ratio was improved, allowing a minor minute ventilation required in clonidine group patients, specially during admission to intensive care.
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PMID:[Effects of clonidine vs trinitroglycerin on myocardial oxygen balance and on pulmonary gas exchange after myocardial revascularization]. 835 64

The effect of low-dose dopexamine and dopamine on gastric intramucosal pH (pHi) during cardiac surgery and 16 hours postoperatively was studied in 35 adults patients (coronary artery bypass grafting and/or valve replacement). The patients were assigned randomly to treatment groups with either dopexamine (1 microgram.kg-1.min-1 (n = 12), dopamine 2.5 micrograms.kg-1.min-1 (n = 11) or to a control group (n = 12). The infusions were started after induction of anaesthesia and were continued until 16 hours after CPB. pHi and arterial pH (pHa) did not differ between groups and remained unchanged during cardiopulmonary by-pass and for the first four postoperative hours. Both the carbon dioxide tension of arterial blood (PaCO2) and of the saline in the tonometer (PtonCO2) changed in parallel with a decrease during CPB and an increase after CPB and surgery with maximal values 12 hours after termination of CPB. A significant correlation was noted between pHi and pHa and between arterial and tonometric PCO2. It is concluded that low dose dopexamine and dopamine have no influence on pHi during and after cardiac surgery. The observed changes in pHi and PtonCO2 were due to changes in pHa and in PaCO2 and not a sign of gastric mucosal ischemia.
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PMID:Dopexamine and dopamine in the prevention of low gastric mucosal pH following cardiopulmonary by-pass. 860 11

The purpose of this study was to examine retrospectively the effect of amrinone on platelet counts and blood transfusion volume during CABG. Patients were divided into two groups. Amrinone group included 40 patients and for comparison another group included 33 patients who had undergone CABG without amrinone. Anesthesia and surgical procedures were standardized and similar for all patients. Platelet counts and hematocrit levels were measured in the arterial blood before CPB, at the end of CPB (after treatment with amrinone in amrinone group), 1 day, 3 days, and 7 days after surgery. Time course of changes in platelet counts was the same between the groups at the following points: before CPB, after CPB, 1 day, 3 days, and 7 days after surgery. We administered amrinone to patients who underwent CABG. The titrated dose of amrinone (about 29mg.kg-1) has not affected the time course of changes in platelet counts and blood transfusion volume.
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PMID:[Amrinone administration exerts no deleterious effect on platelet counts and blood transfusion volume during CABG]. 884 93


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