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J E Wynands

Publications and source records attributed to J E Wynands.

At least 19 recordsLinked to original sources
PubMed1999

Profound hypoxemia during treatment of low cardiac output after cardiopulmonary bypass.

PURPOSE: To illustrate the multiple causes of hypoxemia to be considered following cardiopulmonary bypass and how therapy given to improve oxygen delivery may have contributed to a decrease in arterial oxygen saturation to life-threatening levels. CLINICAL FEATURES: A 61 yr old man with severe mitral regurgitation and chronic obstructive lung disease underwent surgery for mitral valve repair. A pulmonary artery catheter with the capacity to measure cardiac output and mixed venous oxygen saturation (SvO2) continuously was used. Two unsuccessful attempts were made to repair the valve which was finally replaced, requiring cardiopulmonary bypass of 317 min. Dobutamine 5 micrograms.kg-1.min-1 and sodium nitroprusside 1 microgram.kg-1.min-1 were used to increase cardiac output. Soon after, the SvO2 decreased progressively from 55 to 39%. The patient became cyanotic with a PaO2 of 39 mmHg. Sodium nitroprusside was stopped and amrinone 100 mg bolus followed by 10 micrograms.kg-1.min-1 was given in addition to adding PEEP to the ventilation. With these measures PaO2 could be maintained of safe levels but PEEP and high inspired oxygen concentrations were needed postoperatively until the trachea could be extubated on the third postoperative day. CONCLUSION: The profound hypoxemia in this case was likely due to a combination of intra- and extrapulmonary shunt, both augmented by sodium nitroprusside. The desaturation of mixed venous blood amplified the effect of these shunts in decreasing arterial oxygen saturation. The interaction of these factors are analyzed in this report.

Amrinone↗
PubMed1996

Pharmacodynamics of doxacurium during cardiac surgery with hypothermic cardiopulmonary bypass.

PURPOSE: To determine the characteristics of neuromuscular block produced by two and three times the 95% effective dose (ED95) of doxacurium in patients undergoing coronary artery surgery with hypothermic cardiopulmonary bypass. METHODS: In a prospective non randomized study, ten patients received doxacurium 0.05 mg.kg-1 (Group 1) and ten others received 0.075 mg.kg-1 (Group 2) with midazolam and sufentanil. The mechanomyographic response of the adductor pollicis muscle after supramaximal train-of-four (TOF) stimulation of the ulnar nerve was recorded intraoperatively and postoperatively. Additional doxacurium (10% of the initial dose) was administered until sternal closure whenever the first twitch (T1) had recovered to 25% of control. RESULTS: The onset time (time to maximal T1 depression) of doxacurium was 390 +/- 148 sec in Group 1 and 370 +/- 74 sec in Group 2 (P = 0.71). The clinical duration of neuromuscular block (time to 25% T1 recovery) was 165 +/- 90 min in Group 1 and 258 +/- 86 in Group 2 (P = 0.03). On arrival to recovery room the mean T1 was 57 +/- 23% in Group 1 and 24 +/- 21% in Group 2 (P = 0.003); the mean T4/T1 ratio was 0.25 +/- 0.15 for five patients of Group 1 with four responses to TOF stimulation and 0.10 for the only patient of Group 2 with four twitches. CONCLUSION: In contrast with findings in patients without cardiac disease, this study shows comparable onset times of doxacurium with doses of two and three times ED95. The clinical duration of doxacurium is 60 to 100% longer than previously reported in noncardiac surgery.

Aged↗
PubMed1996

The contribution of Canadian anaesthetists to the evolution of cardiac surgery.

PURPOSE: There have been great improvements in the management of patients with heart disease over the past 50 yr much of which has been due to the development of surgical procedures for the correction of acquired and congenital cardiac abnormalities. A great deal has been written about the surgeons and the innovative procedures they developed. They were undoubtedly courageous, imaginative, knowledgeable and skillful. Little is written about the anaesthetists who often worked in the laboratory with the surgeons and provided anaesthesia for patients having this surgery which, in the early days, was experimental. The purpose of this article is to present the contributions made by Canadian anaesthetists to the evolution of cardiac surgery. PRINCIPAL FINDINGS: The contributions have been important over five clearly discernable eras and have been identified through publications. Canadian anaesthetists wrote about their experience giving anaesthesia for mitral commissurotomy, relief of pulmonic stenosis, ligation of patent ductus arteriosus, resection of aortic coarctation, correction of simple congenital heart defects under hypothermia and myocardial revascularization. When open heart surgery was introduced, Canadian anaesthetists working both in the United States and Canada were amongst the first to publish on surgery supported by cardiopulmonary bypass and anaesthesia for these procedures. CONCLUSION: An analysis of the literature and personal, verbal and written communications with anaesthetists who experienced the trials and tribulations of anaesthesia for these early surgical procedures clearly indicates that Canadians were at the forefront in advancing anaesthesia for cardiac surgery.

Anesthesiology↗
PubMed1995

The management of temperature during cardiopulmonary bypass: effect on neuropsychological outcome.

Laboratory studies demonstrate that mild degrees of brain cooling (2 degrees C to 5 degrees C) confer substantial protection from ischemic brain injury, and that mild elevation of brain temperature can be markedly deleterious. During hypothermic cardiopulmonary bypass (CPB) patients are made hypothermic and then rewarmed at a time when they are exposed to neurological insults. Our studies show that during rewarming, peak brain temperatures near 39 degrees C often are achieved inadvertently. We hypothesize that maintaining brain temperature < or = 34 degrees C during and after CPB will reduce the incidence of postoperative neuropsychological deficits. We present safety data from a study of 30 patients assigned either to conventional hypothermic CPB with rewarming or a protocol where brain temperature is raised only to 34 degrees C at the time of separation from CPB. There was no difference in bleeding, cardiac morbidity, or time to extubation between groups. We designed a neuropsychological test battery to detect postoperative neuropsychological deficits and tested its usefulness in a preliminary sample of 15 patients undergoing hypothermic CPB. We found patient acceptability and compliance were good. Sensitivity also seemed adequate in that 30% of patients were identified as having deteriorated at 1 week postoperatively compared to preoperatively, a result similar to that reported by others. Clinical trials of the efficacy of mild hypothermia in modulating brain injury in humans are needed before techniques of CPB can be designed to optimize neuroprotection.

Aged↗
PubMed1995

Effects of routine premedication for cardiac catheterization on sedation, level of anxiety and arterial oxygen saturation.

OBJECTIVE: To assess the efficacy and side effects of routine premedication in patients undergoing cardiac catheterization procedures in a tertiary cardiac care institute. The criteria used included: arterial hemoglobin oxygen saturation (%SaO2), level of sedation and level of anxiety before and after the procedure. Overall patient satisfaction was also quantified. DESIGN: Sixty-two adult patients scheduled for cardiac catheterization procedures were recruited for the study. They were premedicated with one of several premedication regimens: oral diazepam 5 to 10 mg; oral lorazepam 1 mg; oral diazepam 10 mg+oral promethazine 25 mg; or oral diazepam 10 mg+oral diphenhydramine 25 mg. No attempt was made to control the premedication the patients received; it was ordered by each patient's cardiologist according to personal preference. Patients underwent pulse oximetry and evaluation of sedation, anxiety and level of satisfaction before and after cardiac catheterization. RESULTS: All patients tested had values for mean precatheterization %SaO2 above 92%. No patient had postcatheterization %SaO2 readings below that defined as indicating clinically significant hypoxemia (%SaO2 less than 90%). Patients were awake or lightly sedated before and after cardiac catheterization. Thirteen per cent of patients suffered from high levels of anxiety before, and 16% during, cardiac catheterization. Twenty-three per cent of patients reported being dissatisfied with the premedication before, and 10% of patients reported being dissatisfied during, cardiac catheterization. CONCLUSIONS: Clinically significant hypoxemia and oversedation are not problems for most patients given the types and doses of precatheterization medication used in the study population. The premedication schedules followed in the study failed to provide satisfaction and anxiolysis in a significant number of those studied.

Aged↗
PubMed1994

The role of amrinone in treating heart failure during and after coronary artery surgery supported by cardiopulmonary bypass.

Amrinone and dobutamine compare favorably in the treatment of chronic congestive heart failure. There is increasing evidence that amrinone alone or in combination with a catecholamine may be used with considerable success in treating patients who are difficult to wean from cardiopulmonary bypass or who have a low cardiac output syndrome after coronary artery bypass grafting surgery. Amrinone increases intramyocardial cyclic adenosine monophosphate and exerts positive inotropic activity in addition to being a potent vasodilator. It may also improve diastolic function by increasing sarcoplasmic reticulum reuptake of calcium during diastole. It has been administered to patients prior to weaning from cardiopulmonary bypass and has improved hemodynamics and oxygen transport. When compared with dobutamine as primary treatment for depressed myocardial function in patients being weaned from cardiopulmonary bypass after coronary artery bypass grafting surgery, it was more effective in achieving primary treatment objectives. Patients given dobutamine had a higher incidence of myocardial infarction, ventricular fibrillation, supraventricular tachyarrhythmias, sinus tachycardia, and hypertension compared to those given amrinone. It is concluded that amrinone compares favorably with dobutamine and may even be superior when used as primary treatment for treating myocardial depression in patients having coronary artery surgery supported by cardiopulmonary bypass.

Amrinone↗
PubMed1994

Pure opioid versus opioid-volatile anesthesia for coronary artery bypass graft surgery: a prospective, randomized, double-blind study.

This study was designed to assess, in a prospective, randomized, blinded fashion, the hemodynamic effects of different anesthetics used in the prebypass period during coronary artery bypass grafting (CABG) and the effect on incidence of ischemia. Seventy-five patients were randomly assigned to receive sufentanil increments, isoflurane, or enflurane after a standard premedication and anesthetic induction with sufentanil 5 micrograms/kg. Myocardial ischemia was monitored intraoperatively by the anesthesiologist with electrocardiogram (ECG) leads V5(CB5) and II, and by a Holter monitor of the same leads from which recordings were analyzed postoperatively by a cardiologist. A continuous recording of the blood pressure was analyzed to determine the duration of hypertensive responses. Arterial blood pressure control was best in the patients supplemented with anesthetic vapors; patients receiving beta-adrenergic blockers or those receiving isoflurane were less likely to require treatment for tachycardia. All episodes of myocardial ischemia occurred within 5 min of induction-intubation and were diagnosed more frequently by the anesthesiologist than on the Holter monitor (29% vs 9%), with no difference between groups. There were five perioperative myocardial infarctions with no difference between groups. After anesthetic induction with sufentanil 5 micrograms/kg, isoflurane or enflurane given during CABG provides better hemodynamic control than increments of sufentanil and is associated with a similar incidence of prebypass ischemia and perioperative infarction.

Coronary Artery Bypass↗
PubMed1994

Pancuronium or vecuronium for treatment of shivering after cardiac surgery.

This randomized double-blind study compared the hemodynamic and metabolic effects of pancuronium and vecuronium during treatment of shivering after cardiac surgery with hypothermic cardiopulmonary bypass. Thirty sedated and pain-free patients who shivered after cardiac surgery were treated with pancuronium (n = 15) or vecuronium (n = 15) 0.08 mg/kg. Baseline values of heart rate (HR), mean arterial pressure, arterial and venous blood gases, total body oxygen consumption indexed to body surface area (VO2-I), and pressure work index (PWI, an estimate of myocardial oxygen consumption) were measured on arrival in the intensive care unit, at onset of shivering, and repeatedly for 2 h after treatment. Continuous ST segment analysis of leads II and V5 were used for detection of myocardial ischemia. Treatment of shivering with pancuronium decreased VO2-I by 32% (P = 0.0001). This was accompanied by a 14% increase in HR (P = 0.001) and a 10% increase in PWI (P = 0.03). Vecuronium decreased VO2-I by 36% (P = 0.003) with a 4% decrease in HR (P = 0.04) and a 6% decrease in PWI (P = 0.06). Myocardial ischemia (n = 3) and ventricular arrhythmias (n = 3) occurred in five patients treated with pancuronium. Only one patient treated with vecuronium had ventricular arrhythmia (P = 0.08). Seven patients treated with pancuronium and eight treated with vecuronium were taking beta-adrenergic blockers preoperatively which was associated with lower HR (96 +/- 16 vs 109 +/- 15 bpm; P = 0.025) and lower PWI (8.8 +/- 1.2 vs 10.7 +/- 1.92 mL.min-1 x 100 g-1; P = 0.003) at onset of shivering. However, beta-adrenergic blockers did not attenuate the relative HR increase induced by pancuronium. No relationship was found between hypercapnia and tachycardia or hypertension. These results suggest that, when compared to pancuronium for treatment of postoperative shivering, vecuronium may be advantageous because it does not increase myocardial work. The disproportionate relationship between VO2-I and PWI after treatment with muscle relaxants indicates that increased VO2-I does not contribute significantly to the hemodynamic disturbances associated with shivering. These disturbances are more likely the results of increased adrenergic activity related to pain and recovery from anesthesia. Shivering and its associated hemodynamic disturbances appear to be concomitant but independent signs of awakening.

Acid-Base Equilibrium↗
PubMed1993

Oxygen transport.

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Biological Transport↗
PubMed1992

Amrinone before termination of cardiopulmonary bypass: haemodynamic variables and oxygen utilization in the postbypass period.

One hundred patients were randomly allocated to receive saline or amrinone, 0.75 mg.kg-1, ten minutes before separation from cardiopulmonary bypass (CPB) after elective coronary artery bypass grafting, in order to determine the effects of this agent on haemodynamic variables and O2 utilization. Anaesthesia and CPB were managed in a standard fashion. Before induction of anaesthesia, at pericardiotomy, then at 1, 10, 20 and 30 min after CPB, haemodynamic profiles, haematocrit, and O2 saturation of arterial and mixed venous blood were measured. Incremental doses of ephedrine or phenylephrine, or an infusion of norepinephrine with phentolamine were administered when required. The groups were demographically similar and surgical variables were also similar. Haemodynamic measurements were similar between groups at all times; however, a higher dose of phenylephrine was given immediately before weaning from CPB in the amrinone group, and more patients in this group received phenylephrine in the first 30 min after CPB. Mixed venous saturation (SvO2) was higher in the amrinone patients at all times after CPB, leading to lower calculated oxygen consumption (VO2) (P less than 0.05). Insufficient dosage may explain the lack of haemodynamic effect, while possible reasons for the higher SvO2 and lower VO2 are either reduced whole body VO2 or peripheral shunting.

Amrinone↗
PubMed1992

Amrinone and dobutamine as primary treatment of low cardiac output syndrome following coronary artery surgery: a comparison of their effects on hemodynamics and outcome.

This study was undertaken in order to compare the effectiveness of amrinone and dobutamine as primary treatment of a low cardiac output (CO) after coronary artery bypass graft (CABG) surgery. Thirty patients with preoperative left ventricular dysfunction participated in this open-label randomized study. Patients were included if they failed to separate from cardiopulmonary bypass (CPB) without inotropic support or if they had a cardiac index (CI) less than 2.4 L/min/m2 after CPB regardless of the blood pressure, in the presence of adequate filling pressures. The treatment objectives were to separate from CPB and achieve a CI > or = 2.4 L/min/m2 and a mean arterial pressure > or = 70 mmHg. Patients treated with amrinone received 0.75 mg/kg followed by 10 micrograms/kg/min; when the objectives were not achieved within five minutes, another 0.75 mg/kg was given. Patients treated with dobutamine received an initial infusion of 5 micrograms/kg/min increased stepwise to 15 micrograms/kg/min if necessary. Eleven of 15 amrinone versus 6 of 15 dobutamine patients achieved the predefined treatment objectives with the test drug alone (P = NS). Comparisons of hemodynamics in patients treated solely with amrinone (n = 7) or dobutamine (n = 6) after CPB showed no significant differences between the treatment groups. The incidence of myocardial ischemia as detected by Holter monitor was 36% with amrinone and 33% with dobutamine. Two patients suffered ventricular fibrillation and two had significant supraventricular tachyarrhythmias (heart rate > 130/min) during treatment with dobutamine alone, whereas no significant arrhythmias occurred in the amrinone group (P = NS). Six dobutamine patients (40%) had postoperative myocardial infarction (MI) as opposed to none among the amrinone patients (P = 0.017). These results indicate that amrinone compares favorably with dobutamine as a primary treatment of low CO after CABG. Further study in a larger number of patients will be required in order to determine if the lower incidence of MI in the amrinone group was due to the treatment drug.

Amrinone↗
PubMed1991

Clinical application of cardiac risk indices: how to avoid misleading numbers.

Perioperative cardiac complications are associated with a high mortality rate. During the preoperative assessment the anaesthetist must determine if the patient is at risk so that appropriate interventions can be made to ensure the best possible outcome. Over the past three decades several indices have been proposed to identify the surgical patient at risk of cardiac morbidity or mortality. These indices can be thought of as diagnostic tests which determine the likelihood of perioperative cardiac complication. In this article the authors review the epidemiological basis of diagnostic tests and apply this theory to three currently available indices of perioperative risk: the American Society of Anesthesiologists physical status classification, the Goldman multifactorial cardiac risk index and a modified version devised by Detsky. A case history describing a surgical patient with unstable angina is first presented to show how different indices can lead to different predictions. These indices are then analysed as if they were diagnostic tests to predict cardiac complications after surgery. The characteristics of diagnostic tests such as sensitivity, specificity, positive and negative predictive values, and receiver operating characteristic curves are described and applied to the indices. Basic principles such as odds ratio, likelihood ratio and their relation to prevalence and post-test probability are also presented. This overview will help the anaesthetist to understand the limitations of risk indices as predictors of adverse cardiac outcome and to apply these scales more effectively to individual patients at different institutions.

Anesthesia↗
PubMed1991

Bolus administration of esmolol for controlling the haemodynamic response to tracheal intubation: the Canadian Multicentre Trial.

A multicentre trial was designed to determine the dose-response and side-effects of esmolol when administered as a single iv bolus prior to induction of anaesthesia for controlling the haemodynamic response to tracheal intubation. Five hundred and forty-eight patients from 12 university-affiliated centres across Canada were randomized prospectively to receive either placebo (PLAC) or esmolol (E) in a dose of 100 mg (E100) or 200 mg (E200). Study medication was given immediately before induction of anaesthesia with thiopentone 3-5 mg.kg-1 and succinylcholine 1.5 mg.kg-1. Low-dose narcotic (fentanyl 2-3 micrograms.kg-1 or sufentanil 0.3 micrograms.kg-1) or moderate dose narcotic (fentanyl 4-7 micrograms.kg-1) was also given at five of the participating centres, whereas patients in the remaining seven centres received no narcotic. Patients who received PLAC and no narcotic had greater HR and SBP values after tracheal intubation than patients who received either E100 or E200 (P less than 0.005). The proportion of patients whose maximum HR exceeded 110 min-1 was also greater in the PLAC group (22/180) than in either the E100 (10/187) or E200 (9/181) groups (P less than 0.05), but was not different when comparing E100 with E200. Esmolol was less effective in controlling blood pressure, but, in combination with low-dose narcotic, esmolol suppressed the SBP response to tracheal intubation. In the presence of moderate-dose narcotic, however, a decrease in SBP occurred in all three groups following induction of anaesthesia (P less than 0.003), with the largest decrease (17 +/- 4%) occurring in patients who had received E200. The overall incidence of hypotension (SBP less than 90 mmHg) was greater in the E200 group (33%) than either the E100 (25%) or PLAC (16%) groups (P less than 0.05). Other side-effects, such as bradycardia, bronchospasm or pain on injection, occurred no more frequently in either esmolol group than with placebo. It is concluded that a 100 mg bolus of esmolol is safe and effective for controlling the haemodynamic response to tracheal intubation. This dose of esmolol combined with a low dose of narcotic (fentanyl 2-3 micrograms.kg-1 or equivalent) results in effective control of both heart rate and blood pressure, while avoiding important side-effects.

Adrenergic beta-Antagonists↗
PubMed1990

Pharmacokinetics of alfentanil and clinical responses during cardiac surgery.

This study assessed the pharmacokinetic and pharmacodynamic behaviour of alfentanil during and after coronary artery bypass grafting (CABG). Twenty-eight patients with good ventricular function having CABG were divided into three groups and premedicated with morphine 0.1 mg.kg-1 IM, scopolamine 0.005 mg.kg-1 IM and diazepam 0.1 mg.kg-1 PO. Group I patients received an infusion of 250 micrograms.kg-1 of alfentanil over one hour coincidental with a second infusion at 2.5 micrograms.kg-1.min-1 which was continued to the end of surgery. Patients in group II received 300 micrograms.kg-1 and 3.0 micrograms.kg-1.min-1 and patients in group III 350 micrograms.kg-1 and 3.5 micrograms.kg-1.min-1. The tracheas of all patients were intubated after receiving alfentanil 96 micrograms.kg-1 and pancuronium 0.15 micrograms.kg-1. Haemodynamic responses to intubation and surgical stimuli (greater than or equal to 20 per cent increase in heart rate and/or systolic blood pressure from control) were treated with isoflurane, one to two per cent inspired, until abolished. Blood samples were taken during and after surgery for plasma alfentanil concentrations which were determined by radioimmunoassay. After surgery the times to awakening and extubation, and alfentanil elimination half-life (t1/2B = 0.693/-k) were determined for each patient. Haemodynamic responses occurred in 20 patients. There were no significant differences in any variable among the groups. The times to awakening and extubation for all patients were 3.2 +/- 0.6 and 8.8 +/- 1.2 hr (mean +/- SEM) respectively. The elimination half-life for all patients was 5.1 +/- 1.0 hr (mean +/- SEM).(ABSTRACT TRUNCATED AT 250 WORDS)

Alfentanil↗