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Biomedical subjects

J E Wynands

Publications and source records attributed to J E Wynands.

At least 37 records · Page 2Linked to original sources
PubMed1989

Amrinone: is it the inotrope of choice?

In the treatment of acute heart failure, conventional therapy with epinephrine, norepinephrine, dopamine, and dobutamine may be used effectively to treat inotropic abnormalities. However, the addition of a vasodilator to catecholamine therapy may be needed to help improve lusitropic function. Because it seems to exert positive inotropic and lusitropic effects, the phosphodiesterase inhibitor amrinone may be a valuable addition to the anesthesiologist's armamentarium for the treatment of acute heart failure. When used as adjunctive therapy with catecholamines, amrinone has been shown to exert a significant additive and synergistic effect. Amrinone may also be the inotrope of choice in patients who are refractory to therapy with conventional inotropes, due to its positive inotropic and lusitropic effects, combined with its vasodilating effects. Because of its broad pharmacodynamic spectrum, amrinone may effectively control all of the major elements involved in myocardial performance--preload, afterload, contractility, and heart rate.

Amrinone↗
PubMed1989

The incidence of myocardial ischemia during anesthesia for coronary artery bypass surgery in patients receiving pancuronium or vecuronium.

This study was performed to compare the incidence of prebypass myocardial ischemia in patients receiving fentanyl and enflurane for anesthesia along with either pancuronium or vecuronium. Ninety-eight patients with normal left ventricular function were randomly allocated to receive either pancuronium 0.15 mg.kg-1 or vecuronium 0.15 mg.kg-1 in a double-blind manner after fentanyl 40 micrograms.kg-1 for induction of anesthesia for elective coronary artery bypass grafting (CABG). Premedication included diazepam 0.15 mg.kg-1 po, morphine 0.10 mg.kg-1, and scopolamine 0.005 mg.kg-1 im. Two lead Holter monitor recordings (leads V6 and V9) from the time of arrival in the operating suite to institution of cardiopulmonary bypass were analyzed for ischemia by a cardiologist blinded to the choice of muscle relaxant. Intraoperatively, heart rates greater than 90 beats.min-1 and systolic blood pressure +/- 20% of ward values were treated with propranolol, enflurane, or phenylephrine. Nitroglycerin was infused for ECG signs of ischemia or pulmonary hypertension. After induction of anesthesia the heart rate and cardiac index were consistently decreased in patients receiving vecuronium and also lower in these patients compared with those receiving pancuronium. Thirty-two per cent of patients receiving pancuronium received propranolol for heart rates greater than 90 beats.min-1 versus 7% of those who received vecuronium (P approximately 0.01). Eight patients developed 13 episodes of ischemia after administration of the muscle relaxant: four who received pancuronium (n = 44; 9%) and four receiving vecuronium (n = 54; 7%). Four episodes occurred at induction or tracheal intubation, two in each group. There were four perioperative myocardial infarctions as determined by ECG and CPK-MB levels, two in each group.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1988

The effects of shivering on oxygen consumption and carbon dioxide production in patients rewarming from hypothermic cardiopulmonary bypass.

Oxygen consumption (VO2), carbon dioxide production (VCO2), end-tidal carbon dioxide partial pressure (PETCO2), mixed venous oxygen saturation (SvO2) and haemodynamic variables were recorded every 30 min for four hours in 15 patients recovering from hypothermic cardiopulmonary bypass (CPB). All patients had been anaesthetised with fentanyl 40 micrograms.kg-1, supplemented with isoflurane, and pancuronium 0.15 mg.kg-1 for muscle relaxation. Three of the 15 patients (20 per cent) shivered, defined as intermittent or continuous, vigorous movements of chest or limb muscles. Patients who shivered had a VO2 of 159 +/- 16.4 ml.min-1.m-2 on arrival in the ICU which rose to a maximum value of 254 +/- 28.3 ml.min-1.m-2 by 150 min post-CPB. In contrast, patients who did not shiver had a significantly lower VO2 of 93.1 +/- 6.9 ml.min-1.m-2 on arrival in the ICU which rose to a maximal value of only 168 +/- 11.5 ml.min-1.m-2 by 180 min post-CPB. Maximal VO2 in both groups was reached when the nasopharyngeal temperature (NPT) was approaching normal. VCO2 paralleled the increase in VO2 in both groups. By four hours there was no significant difference between the two groups; however, the VO2 in both groups (160.5 +/- 21.3 ml.min-1.m-2 and 173.9 +/- 12.3 ml.min-1.m-2 respectively) was approximately twice values commonly measured in anaesthetized patients. Patients who shivered had a significantly higher heart rate and cardiac index and significantly lower SvO2. We conclude that the high VO2 and VCO2 associated with shivering causing increased myocardial work may be detrimental to patients who have impaired cardiac function post-coronary artery surgery (CAS).

Aged↗
PubMed1988

The incidence of prebypass dysrhythmias in patients undergoing coronary artery surgery.

The incidence of dysrhythmias during the prebypass period of coronary artery surgery has not been accurately reported. Using Holter monitoring of the electrocardiogram, this study was undertaken to determine the incidence of dysrhythmias and ischemia and their relationship to specific events during the prebypass period. The role of preoperative calcium entry blockers (CEB), beta-adrenergic blockers (BB), or both on the incidence of dysrhythmias and ischemia was also studied. One hundred thirty-eight patients were premedicated with morphine, scopolamine, and diazepam. Anesthesia was induced with fentanyl or sufentanil followed by either pancuronium or vecuronium and maintained with sufentanil or enflurane. All 138 patients experienced a dysrhythmia during the prebypass period. Seventy-five percent of the patients had at least one episode of a supraventricular dysrhythmia (SVD), 39% had a sinus bradycardia, and 20% had a conduction abnormality. Ninety-two percent of the patients had premature ventricular contractions (PVC) and, surprisingly, 76% had non-sustained ventricular tachycardia. One patient developed ventricular fibrillation and one had ventricular tachycardia. The peak incidence of dysrhythmias occurred at insertion of the pulmonary artery (PA) catheter and at aortic dissection. The incidence of prebypass ischemia was 18%, but these patients did not have a higher incidence of ventricular dysrhythmias. Preoperative CEBs and BBs did not influence the incidence of ischemia or dysrhythmias with the exception of SVD; there was a significantly lower incidence at PA catheterization in patients taking CEBs preoperatively (P < .05). It can be concluded that dysrhythmias are very common during the prebypass period. The low rate of progression to life-threatening dysrhythmias may be related to the fact that the majority occurred during mechanical stimulation and that patients were chronically taking CEBs and/or BBs preoperatively.

Adrenergic beta-Antagonists↗
PubMed1987

The relationship between central venous pressure and pulmonary capillary wedge pressure during aortic surgery.

Twenty-three ASA physical status II-III patients scheduled for elective abdominal aortic surgery were studied preoperatively with multiple unit gated acquisition angiography (MUGA) scan to determine the resting left ventricular and right ventricular ejection fractions (LVEF and RVEF respectively). Intraoperatively pulmonary capillary wedge pressure (PCWP) and central venous pressure (CVP) were measured in each patient at five different time periods in the horizontal, 24 degrees head up, and 24 degrees head down table tilt positions. The correlation between absolute values and changes in PCWP and CVP, and the degree to which preoperative knowledge of LVEF and RVEF predicted these correlations were examined. Resting LVEF ranged from 0.1 to 0.84. Thirteen of the 23 patients failed to show significant correlation (p less than 0.05) between the absolute values of PCWP and CVP either before and/or after aortic crossclamp. When the correlation coefficients from this analysis were ranked against LVEF, there was a weak but significant correlation before aortic crossclamp (r = 0.41), but not after. The correlation between a change in PCWP and a change in CVP was significant for the 23 patients at all time intervals, before and after aortic crossclamp. However, the prediction of a change of PCWP value from a known change of CVP value ranged in accuracy from +/- 3 mmHg to +/- 12.5 mmHg. The study suggests that if the filling pressures of both ventricles need to be assessed during aortic surgery, then the PCWP and CVP must be independently measured.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1987

The role of intrathecal morphine in the anesthetic management of patients undergoing coronary artery bypass surgery.

The study was undertaken to assess the effects of intrathecal morphine (ITM) on perioperative hemodynamics, and anesthetic and postoperative analgesic requirements in patients anesthetized with fentanyl/enflurane undergoing coronary artery bypass surgery. Forty patients were randomized in a double-blind fashion to receive either intrathecal morphine or saline. Nineteen patients received ITM, 0.02 mg/ kg, and 21 intrathecal saline (ITS) after induction of anesthesia. Anesthesia included fentanyl, 40 microg/kg, and pancuronium, 0.15 mg/kg, and was supplemented with enflurane when systolic blood pressure was 20% higher than ward pressure. Intrathecal morphine did not improve hemodynamic stability or reduce enflurane requirements perioperatively. No significant difference was found between ITM and ITS groups for postoperative requirements of morphine (3.5 +/- 0.5 v 4.5 +/- 0.6 mg), diazepam (5.6 +/-1.25 v 3.9 +/- 1.26 mg), and vasodilators (6 v 13 patients), respectively. Comparable and significant reductions of peak expiratory flow rates (PEFR), forced vital capacity (FVC), and forced expiratory volume (FEV1) occurred in both groups postextubation when compared with preoperative values. Intrathecal morphine at the dose of 0.02 mg/kg does not offer any clear benefit to patients anesthetized with fentanyl, 40 microg/kg, for coronary artery bypass surgery.

Adjuvants, Anesthesia↗
PubMed1987

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Anesthesiology↗
PubMed1987

Hemodynamic variables and the incidence of prebypass ischemia during sufentanil/O2/pancuronium anesthesia in patients undergoing coronary artery surgery.

It has been suggested that sufentanil is a superior anesthetic to fentanyl for patients undergoing myocardial revascularization. This study was performed to determine the incidence of prebypass myocardial ischemia using sufentanil, 20 micrograms/kg for patients undergoing coronary artery bypass grafting (CABG). Twenty-seven patients with normal left ventricular function, scheduled for elective CABG, were studied. Anesthesia was induced with sufentanil, 10 micrograms/kg; and pancuronium, 0.1 mg/kg, was given for muscle relaxation. Further increments of sufentanil, 5 micrograms/kg, were given before skin incision and sternotomy. All patients had ECG leads V6 and V9 recorded continuously with a Holter monitor from arrival in the operating room until the start of bypass. Hemodynamic profiles were recorded at specific intervals in the prebypass period. Seven patients (25.9%) developed prebypass myocardial ischemia, three at intubation, and three at aortic dissection. Fourteen patients developed hypertension and 14 had hypotension, defined as increases or decreases greater than 20% from baseline values, respectively. Only five patients had neither hypotension nor hypertension. Three patients (11.1%) had perioperative myocardial infarctions, two of whom had prebypass myocardial ischemia. It is concluded that the incidence of prebypass ischemia with sufentanil anesthesia approximates 26%, which is similar to other studies using sensitive ECG monitoring techniques for the detection of ST segment changes. Hemodynamic instability, in the form of bradycardia, hypertension and hypotension, but not tachycardia, may have contributed to the incidence of prebypass ischemia.

Aged↗
PubMed1985

Early extubation after high-dose fentanyl anaesthesia for aortocoronary bypass surgery: reversal of respiratory depression with low-dose nalbuphine.

To investigate the possibility of selective reversal of narcotic-induced respiratory depression following fentanyl anaesthesia, we studied 20 patients after aortocoronary bypass surgery. All patients were anaesthetized with fentanyl, 40 micrograms . kg-1 and oxygen, with isoflurane as indicated. In a random double blind fashion either incremental doses of nalbuphine, or normal saline were administered approximately four hours after cardiopulmonary bypass. Respiratory depression was evaluated using blood gas and end tidal CO2 (PETCO2) measurement, and in addition, a ventilatory response to CO2 was obtained preoperatively and at selected intervals postoperatively. Despite randomization, patients with more respiratory depression were assigned to nalbuphine. There appeared to be a reversal of respiratory depression with nalbuphine, indicated by a fall in the resting PETCO2 value. This apparent reversal of respiratory depression was associated with a significant increase in pain, requiring treatment in three patients. We conclude that low-dose nalbuphine is not an acceptable method of antagonism of respiratory depression in this group of patients. Many patients who did not receive nalbuphine were able to breathe adequately at an earlier stage than was previously suspected. Close monitoring of the respiratory system may permit earlier extubation without the requirement of a narcotic antagonist after this dose of fentanyl.

Anesthesia, General↗
PubMed1985

Site of temperature monitoring and prediction of afterdrop after open heart surgery.

To determine which of the commonly used "core" temperature sites, remote from the brain, best indicates total body rewarming, the temperatures in the rectum (RT), urinary bladder (UBT) and the pulmonary artery (PAT) at the termination of cardiopulmonary bypass (CPB) were correlated with the decrease in nasopharyngeal temperature (NPT) after CPB (afterdrop) in 29 patients. The amount of afterdrop is inversely related to the adequacy of total body rewarming, smaller values indicating better rewarming. All patients had uncomplicated cardiac surgery and received high pump flows during rewarming on CPB. The UBT showed the best correlation with afterdrop (p less than 0.001) compared with the other temperature sites, the durations of CPB and rewarming during CPB, and the time that the NPT was greater than 37 degrees C during rewarming. The urinary bladder is a simple, non-invasive monitoring site when a urinary catheter is required and our results indicated that the UBT is a better monitor of the adequacy of total body rewarming on CPB than NPT alone. The study also suggested that rewarming to a UBT in excess of 36.2 degrees C prior to the termination of CPB is unlikely to further reduce afterdrop.

Adult↗
PubMed1985

Improvement in resting ventricular performance following coronary bypass surgery.

To assess the changes in resting left ventricular (LV) function following coronary bypass surgery, technetium 99m-labeled multiple equilibrated blood pool gated scans were performed in 53 consecutive patients at rest, before operation, and at 24 hours and 1 week after operation. Left ventricular ejection fraction (LVEF) and end-diastolic volume (EDV) were measured. The LVEF increased significantly from a preoperative value of 49 +/- 2% to 56 +/- 2% at 24 hours after operation (p less than 0.05) and 56 +/- 2% at 1 week following operation (p less than 0.05 compared with the preoperative value). The EDV also exhibited significant changes, decreasing from a preoperative value of 148 +/- 8 ml to 91 +/- 11 ml at 24 hours (p less than 0.001) and 114 +/- 9 ml at 1 week (p less than 0.01 compared with the preoperative value). When the patients were divided into two groups according to the preoperative LVEF (Group 1, LVEF of greater than or equal to 50%; Group 2, LVEF of less than 50%), the observed changes were similar. This study demonstrates significant improvement in resting LV function 24 hours following coronary bypass surgery. This improvement persists at 1 week and is not related to the degree of preoperative impairment. We conclude that the combination of successful revascularization and optimal myocardial protection can result in significant improvement of LV function at rest.

Adult↗