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Biomedical subjects

P J Dauchot

Publications and source records attributed to P J Dauchot.

At least 19 recordsLinked to original sources
PubMed1996

Sufentanil with and without diazepam for coronary artery bypass graft surgery.

We studied the sufentanil-sparing effect of diazepam for anesthesia induction and compared stress responses (hemodynamics, plasma catecholamine levels) and sufentanil and diazepam plasma levels during sufentanil anesthesia with or without diazepam. Sixteen aortocoronary bypass surgery patients were randomly assigned to receive diazepam (D) 100 micrograms/kg (Group DS) or not (Group S), then sufentanil (Sf) infused at 150 micrograms/min until unconsciousness (U). After tracheal intubation, the Sf dose for U (Sfu) was repeated, preceded in Group DS by D 150 micrograms/kg. Group DS patients require lower Sfu doses (2.01 +/- 0.23 micrograms/kg vs 4.87 +/- 0.63 micrograms/kg (P < 0.05) and plasma Sf levels (236 +/- 47 ng/100 ml vs 593 +/- 118 ng/100 ml (P < 0.01) and had similar or lower heart rate, systolic and diastolic blood pressure, rate-pressure product, and plasma norepinephrine levels than S patients. Linear regression of mean plasma norepinephrine and sufentanil levels gave correlation coefficients of -0.205 in S and -0.90 in DS (p < 0.05).

Anesthetics, Intravenous↗
PubMed1991

Epinephrine-aminophylline-induced arrhythmias after midazolam or thiopentone in halothane-anaesthetized dogs.

The purpose of this study was to evaluate epinephrine-aminophylline-induced arrhythmias during halothane anaesthesia after induction with thiopentone or midazolam. Ten mongrel dogs were studied during 1 MAC halothane and 50% N2O:O2 anaesthesia while maintaining constant acid-base status. The minimal arrhythmogenic infusion rate of epinephrine (MAIRE) and the corresponding plasma concentration of epinephrine (MAPC) required to produce ventricular arrhythmias before and after aminophylline were higher following induction of anaesthesia with midazolam than with thiopentone (P less than 0.05); the MAIREs decreased stepwise with aminophylline (P less than 0.05). The correlation coefficient between individual MAIREs and MAPCs was 0.93 (P less than 0.001). Epinephrine alone and in combination with aminophylline was less arrhythmogenic after induction with midazolam than with thiopentone.

Aminophylline↗
PubMed1989

Effect of calcium entry and beta blockade during infrarenal aortic clamping.

Clamping and declamping during aortic surgery produce a hemodynamically significant myocardial stress. The cardiovascular (CV) response to this stress may be adversely altered by calcium antagonists and beta-adrenoreceptor blockade employed to control symptomatic coronary artery disease. This study evaluated the effect of verapamil (V), propranolol (P), and their combination (P + V) on the CV response to infrarenal abdominal aortic cross-clamping and declamping in anesthetized dogs. Six dogs received P as a bolus of 0.5 mg/kg 20 min before clamping. Six additional dogs received V as a 300 micrograms/kg bolus followed by a V infusion of 6 micrograms/kg/min for 20 min before clamping. A third group of six dogs received the P bolus followed 20 min later by the V regimen (P + V). In both the V and P + V groups, 6 micrograms/kg/min V was infused throughout the clamping and declamping sequence. A fourth group of six control dogs received no cardioactive drugs during the experiment. Heart rate, mean aortic blood pressure, left ventricular end-diastolic pressures, peak rate of rise of left ventricular pressure, cardiac output, and systemic vascular resistance were measured in all animals before aortic cross-clamping, at 5 and 40 min after clamping, and 5 min after declamping. The results demonstrated additive negative chronotropic and inotropic properties of P + V therapy with a more significantly adverse effect than that of either drug alone. The implications of this study warrant added caution when patients treated with these drugs undergo abdominal aortic surgery.

Adrenergic beta-Antagonists↗
PubMed1989

Effects of nifedipine on the hemodynamic response to clamping and declamping of the abdominal aorta in dogs.

Clamping and declamping of the infrarenal abdominal aorta may adversely affect cardiovascular function, particularly in the presence of heart disease. This effect may be further altered by drugs used in the treatment of symptomatic coronary artery disease. The effect of nifedipine on the hemodynamic response to aortic clamping and declamping was determined in 12 dogs anesthetized with 50% nitrous oxide and 0.6% end-tidal isoflurane and monitored with aortic, left ventricular (LV), and thermodilution pulmonary artery catheters. Six dogs received a nifedipine bolus of 100 micrograms/kg followed by an infusion of 4 micrograms/kg/min. Six dogs did not receive any nifedipine and served as controls. Before clamping, nifedipine produced immediate decreases in arterial pressure, systemic vascular resistance (SVR), and LV dP/dt, and a modest increase in cardiac output (CO). During aortic clamping, nifedipine-treated dogs demonstrated marked increases in heart rate (HR), dP/dt, and CO while maintaining a low SVR. There were no significant changes upon declamping. The nifedipine-treated animals maintained a high CO and low SVR. Thus, nifedipine greatly altered the hemodynamic responses to aortic clamping and declamping. Awareness of these alterations is important when caring for patients being treated with nifedipine who are undergoing aortic surgery.

Analysis of Variance↗
PubMed1986

Glycation of skin collagen in type I diabetes mellitus. Correlation with long-term complications.

Nonenzymatic glycosylation (glycation) of collagen was measured by boronate affinity chromatography in skin biopsies from 41 type I diabetics with mean duration of diabetes of 25 yr (range 20-40 yr) and from 25 age-matched controls. Mean level of Amadori products was significantly increased in diabetic [7.85 +/- 1.78 (SD) nmol/mg collagen] versus control subjects [3.34 +/- 1.06 (SD) nmol/mg collagen, P less than .001] but did not correlate with age, diabetes duration, or severity of retinopathy, nephropathy, arterial stiffness, and joint stiffness. Similarly, mean collagen content per biopsies was 42% increased in diabetic versus control subjects (P less than .001) but did not correlate with age, diabetes duration, or severity of complications. A weak but positive correlation between glycohemoglobin level and glycation of skin collagen was observed. These results indicate that Amadori products cannot explain by themselves the pathogenesis of diabetic complications unless individual tissue response to glycation is different in subjects with and without complication. They do not exclude a role for the late stages of the Maillard reaction, nonenzymatic browning, in the formation of some of these complications.

Adult↗
PubMed1985

The self-tuning controller: comparison with human performance in the control of arterial pressure.

A self-tuning controller was implemented for the automated infusion of sodium nitroprusside to lower mean arterial pressure in anesthetized dogs. The system incorporated a recursive least-squares parameter identifier and a modified minimum-variance controller. The onset delay was estimated on-line, the performance criterion included the cost of control, and requested step-changes were automatically translated into five successive smaller steps to reduce overshoot. The performance of the system in lowering mean arterial pressure was quantitatively compared with that of a well-trained anesthesiologist. In 10 runs in four animals, the automated system performed as well as the physician who devoted 100% of his attention to the task. Since the stability of the self-tuning controller cannot be guaranteed, such a system should be operated only in the presence of appropriate supervisory algorithms.

Anesthesia↗
PubMed1985

Effectiveness of sodium nitroprusside as a function of total peripheral resistance in the anesthetized dog.

To determine the influence of background vasomotor tone on the effectiveness of sodium nitroprusside in decreasing total peripheral resistance, experiments were performed on 12 open-chest dogs under halothane anesthesia. In the first experiment, the vasomotor condition of six dogs was changed by altering the background infusion rate of phenylephrine (0,40, and 0 microgram/min). Increasing background phenylephrine infusion from 0 to 40 micrograms/min significantly enhanced the effectiveness of nitroprusside in decreasing total peripheral resistance. In contrast, the effectiveness of nitroprusside in decreasing arterial pressure was not altered significantly. In a second experiment on six other dogs, phenylephrine was infused continuously at 40 micrograms/min, and the vasomotor condition was changed by the infusion of phentolamine (0, 60-100, 0 microgram/min). Phentolamine significantly diminished the effectiveness of nitroprusside in decreasing peripheral resistance. In contrast, the effectiveness of nitroprusside in decreasing arterial pressure was not altered significantly. Stepwise linear regression analysis indicated that the background peripheral resistance was the hemodynamic variable that could account partially for the changes in nitroprusside effectiveness. Increasing background total peripheral resistance significantly enhanced the effectiveness of nitroprusside in decreasing total peripheral resistance.

Anesthesia, Inhalation↗
PubMed1985

Noninvasive assessment of electroconvulsive-induced changes in cardiac function.

Systolic time intervals were used to noninvasively evaluate the cardiac effects of electroconvulsive therapy (ECT) in eight psychiatric patients. ECT produced a hyperdynamic cardiac state in which there was a significant increase in blood pressure, a shortening of the pre-ejection period (PEP), and an increase in rate pressure product (RPP). Changes in the PEP and the RPP are compatible with increased cardiac contractility and oxygen consumption, respectively. These effects were apparently mediated by an ECT-induced increase in circulating catecholamines, particularly epinephrine.

Adolescent↗
PubMed1983

Activated coagulation and activated partial thromboplastin times in assessment and reversal of heparin-induced anticoagulation for cardiopulmonary bypass.

In 22 adult patients, activated coagulation times (ACT) were compared to activated partial thromboplastin times (aPTT) before, during, and after cardiopulmonary (CP) bypass surgery. After intravenous heparin (150 units/kg), mean ACT increased from 131 +/- 14 (mean +/- SD) to 362 +/- 72 s (P less than 0.001). With 1.5 units of heparin/ml added to the priming solution of the pump, ACT ranged from 230 to 541 s and aPTT was always 300 s or longer. Activated PTT appears to be less sensitive to changing plasma heparin levels than ACT. Heparin neutralization with a protamine/heparin ratio of 1.0 returned ACT and aPTT to preheparin levels. No abnormal bleeding tendency was seen during the recovery period, and ACT and aPTT remained at preheparin levels. In 10 infants and children undergoing open-heart surgery, ACT was measured in response to the same heparin and protamine regimen. Baseline (113 +/- 14 s) and post-heparin (297 +/- 90 s) ACT were shorter in children than in adults (P less than 0.01). After protamine, ACT was still longer than baseline (134 v 113 s, P less than 0.05). Infants and children seem to require more heparin/kg body weight than adults to achieve comparable ACT levels.

Aged↗
PubMed1979

Management of aortocaval fistula due to abdominal aortic aneurysm.

Anasarca and intractable congestive heart failure were the presenting signs of an abdominal aortic aneurysm with aortocaval fistula. Management with careful monitoring of cardiovascular function using a Swan-Ganz catheter before, during, and after surgery resulted in an uneventful recovery.

Aged↗
PubMed1978

Cardiac function and hypercarbia.

In 12 patients with heart disease, hypercarbia was induced for carotid endarterectomy. Anesthesia was maintained with nitrous oxide in oxygen and methoxyflurane. In addition to intra-arterial measurements of blood pressure, cardiac output, systolic time intervals (STI), and pressure time indices (PTI) were determined in order to assess cardiovascular responses in these patients. Internal carotid stump blood pressure was measured in five patients before and after induction of hypercarbia. Mild elevation of the Paco2 level affected systolic time intervals but not heart rate and blood pressure. When Paco2 levels reached 56 to 65 torr, systolic but not diastolic blood pressure rose significantly, heart rate and cardiac output increased, while the shortening in the preejection period (PEP), left ventricular ejection time (LVET), and the decrease in the PEP/LVET ratio signified increased mechanical cardiac activity. Hypercarbia caused intense sympathetic stimulation as demonstrated by twofold to threefold increases in plasma catecholamine levels. Stump blood pressure was elevated. Cardiac oxygen demand was significantly increased, while coronary filling time was shortened, as indicated by the increase in the tension time index and shortening in the diastolic time. This signified a relative myocardial underperfusion. Thus, while hypercarbia to levels of 66 to 70 torr increased internal carotid artery stump pressure, it also caused increased cardiac mechanical activity and concomitant unfavorable balance between myocardial oxygen consumption and supply. The measurement of STI and the computation of PTI provided early detection of alterations in cardiac function.

Aged↗
PubMed1978

Cardiac function during induction and early anesthesia with methoxyflurane. An evaluation using systolic time intervals and pressure time indices.

In addition to the standard monitoring of heart rate and blood pressure, the Systolic Time Intervals were used to evaluate cardiac performance, and the Pressure Time Indices (tension time index = TTI; diastolic pressure time index = DPTI) were used to estimate myocardial oxygen balance. Twelve patients with known heart disease were studied during induction with thiopental, intubation, and early anesthesia with methoxyflurane. Cardiac performance diminished after thiopental; and during methoxyflurane it was reflected in increases in pre-ejection period (PEP) and the ratio PEP/LVET. Intubation resulted in a hyperactive state of the heart, as shown by maximal decreases in PEP and PEP/LVET. Myocardial oxygen balance--estimated from the supply/demand ratio (DPTI/TTI)--was impaired after thiopental. After intubation, DPTI/TTI decreased to its lowest value due to an excess of myocardial oxygen demand (TTI) over myocardial oxygen supply (DPTI), signifying a transitory underperfusion of the subendocardium. During methoxyflurane the oxygen balance was gradually restored towards control value. The Systolic Time Intervals and the Pressure Time Indices provided valuable information on cardiac function not available from standard monitoring alone.

Adult↗
PubMed1977

Radial artery cannulation in 1,000 patients: precautions and complications.

A review of 1,000 radial artery cannulations performed over a 2-year period showed that, with careful selection of patients, by means of the Allen test and Doppler studies, and with the apparatus used, only two serious complications were encountered; embolectomy was necessary in one and arterial reconstruction in another. Twenty-four percent of patients had evidence of diminution of flow, but in none did it persist for more than 2 weeks. Critical factors in reducing complications were a short period of cannulation, use of a Teflon catheter, and a continuous arterial line flush system.

Arm↗