Biomedical subjects

J Y Dupuis

Publications and source records attributed to J Y Dupuis.

7 recordsLinked to original sources

PubMed1992

Intravenous nifedipine for prevention of myocardial ischaemia after coronary revascularization.

We sought to determine the pharmacokinetic and pharmacodynamic behaviour of a continuous infusion of nifedipine given for prevention of myocardial ischaemia following coronary artery bypass graft (CABG) surgery. Patients scheduled for elective CABG, who had good left ventricular function, were included. Only normotensive patients who did not require treatment with vasoactive drugs and were bleeding less than 100 ml.hr-1 following surgery were included. The patients were randomly distributed into two groups: a control group not receiving any treatment and a treated group receiving a bolus (3 micrograms.kg-1.min-1 for 5 min) and maintenance (0.2 micrograms.kg-1.min-1) infusion of nifedipine, starting upon arrival in the recovery room and continuing for four hours. Patients given nifedipine were compared with control patients in order to determine the effects of nifedipine on haemodynamic function and on the postoperative incidence of hypotension, hypertension, myocardial ischaemia and infarction. Continuous 2-lead Holter monitoring was used to detect myocardial ischaemia. Infarction was diagnosed by 12-lead ECGs and by assessment of the MB-isoenzyme creatine kinase. The infusion of nifedipine rapidly achieved and maintained plasma concentrations between 30 and 40 ng.ml-1. The pharmacokinetic studies revealed a systemic clearance of nifedipine of 0.371 +/- 0.101 L.hr-1.kg-1, an apparent volume of distribution of 0.764 +/- 0.288 L.kg-1 and an elimination half-life of 1.4 +/- 0.6 hr. No correlation was found between plasma concentration of nifedipine and mean arterial pressure (MAP). The incidence of postoperative hypotension (MAP < 70 mmHg) and hypertension (MAP > 100 mmHg) was comparable between the groups. All haemodynamic variables were similar in both groups during the study period. Of 23 patients who received nifedipine, none showed evidence of ischaemia within six hours of starting the infusion. During the same period, five of 24 patients in the control group had ST-segment deviation suggestive of myocardial ischaemia (P = 0.05, Fisher's exact test). Three patients in the control group and none in the nifedipine group suffered perioperative myocardial infarction (P = NS). In conclusion, the continuous infusion of nifedipine used in this study is safe and reduces the incidence of myocardial ischaemia in normotensive patients with good left ventricular function following CABG. Further studies of larger number of patients are required to determine the role of calcium entry blockers following coronary artery surgery.

Blood Pressure↗

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↗

PubMed1990

Clinical, electrical and mechanical correlations during recovery from neuromuscular blockade with vecuronium.

In order to determine correlations between electromyographic (EMG), mecanomyographic (MMG) and clinical criteria of adequate recovery from neuromuscular blockade with vecuronium, seven young healthy conscious volunteers were given subparalysing doses of vecuronium. During recovery from neuromuscular blockade, vital capacity, negative inspiratory pressure, peak expiratory flow rate and five-second head lift were assessed. Neuromuscular monitoring included the evoked EMG response of the adductor digiti minimi and the simultaneous evoked MMG response of the adductor pollicis on the same side. We found that all subjects maintained head lift for five seconds at EMG T4T1 of 0.70, and they achieved normal respiratory tests at EMG T4/T1 of 0.90. The MMG T4/T1 needed for the subjects to perform normal respiratory tests was found to be 0.50, at which time six of the seven subjects were able to perform adequately the head lift test.

Adult↗

PubMed1990

Clinical assessment of the muscular response to tetanic nerve stimulation.

The study was undertaken in order to determine clinical tactile evaluation of tetanic nerve stimulation (50 Hz, 5 sec) as a means of detecting fade and possible residual curarization. Forty-four patients were studied and 128 clinical evaluations by eight different observers were performed at various levels of neuromuscular blockade. Tetanic fade was detected reliably by clinical evaluation only when high degrees of fade (tetanic fade ratio of 0.3 or less) were detected with a force-displacement transducer. We conclude that the clinical tactile assessment of the response to tetanic stimulation is not accurate except at very high degrees of fade and that its usefulness in monitoring neuromuscular recovery is doubtful.

Adult↗

PubMed1989

Atracurium and vecuronium interaction with gentamicin and tobramycin.

Drug interactions between the aminoglycosides (tobramycin and gentamicin) and atracurium and vecuronium were studied prospectively in 44 patients. Twenty-two patients had therapeutic serum levels of tobramycin or gentamicin and 22 served as controls. Onset time, clinical duration, and time to spontaneous recovery of T4/T1 ratio of 0.70 after atracurium or vecuronium injection were measured. No statistically significant differences were found in onset time, but clinical duration and time to recovery were significantly longer in patients receiving tobramycin or gentamicin and paralyzed with vecuronium than for controls (P less than 0.01 for clinical duration and P less than 0.0005 for recovery). The neuromuscular block produced by atracurium was not significantly influenced by the presence of therapeutic serum levels of tobramycin or gentamicin. We conclude that for patients treated with these antibiotics, atracurium may present some advantages over vecuronium when a prolonged block is not desired.

Adult↗

PubMedDate not supplied

Regional anesthesia for pacemaker insertion.

Four local or regional anesthesia techniques for the insertion of cardiac pacemaker were studied prospectively in 40 patients. The four techniques studied were: local anesthesia, field block of the supraclavicular nerves, interscalene block at C4, and interscalene block at C6. The three goals of the study were to find the technique that gave the best quality of analgesia, the incidence of complications related to each technique, and the area of sensory innervation of C4. No technique was found to be superior to the others with regard to the quality of analgesia. Interscalene blocks at C4 and C6 were associated with complications and side effects more often than the two other techniques. The authors also suggest that the dermatome of C4 is not under the clavicle but above the clavicle. It was concluded that local anesthesia infiltration at the site of cardiac pacemaker insertion or field block of the supraclavicular nerves are the best techniques for cardiac pacemaker insertion.

Aged↗