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Biomedical subjects

M Pinaud

Publications and source records attributed to M Pinaud.

At least 109 records · Page 6Linked to original sources
PubMed1988

Effects of systemic morphine and epidural bupivacaine on postoperative oxygen consumption during rewarming.

The alterations in hemodynamics and oxygen consumption as a consequence of continuous epidural infusions of bupivacaine at room temperature and conventionally administered morphine were studied during recovery from general anesthesia for total hip replacement. Twenty-four patients were randomized to receive either bupivacaine or morphine in the recovery room. The bupivacaine group received from 6 to 12 ml per hour of 0.25% bupivacaine epidurally. Patients in the morphine group received 0.1 mg/kg of morphine intramuscularly no more frequently than every 4 hours. A pulmonary artery flotation catheter was inserted into each patient to determine hemodynamics and oxygen consumption at three instances: before analgesia, when pulmonary artery blood temperature reached 36 degrees C, and when it reached 37 degrees C. During the rewarming there was a decrease in mean arterial blood pressure and the systemic vascular resistance index and an increase in heart rate. The whole body oxygen consumption index increased in the bupivacaine group at the last measuring point but was stable in the morphine group. There was no effect on the arterial-venous oxygen content difference in either group. At 37 degrees C, the cardiac index and oxygen consumption index were significantly higher in the bupivacaine group than in the morphine group. In contrast to regional analgesia, systemic morphine administration can partially antagonize cardiovascular response to postoperative rewarming because it induces a stable oxygen demand.

Aged↗
PubMed1988

[Can isoflurane be advised for controlled hypotension?].

Since 1983, many papers tell of the usefulness of isoflurane for induced hypotension. It can induce and maintain stable arterial hypotension during neurosurgery, or any other surgical procedure requiring induced hypotension. Its use has proved to be simple. Although other hypotensive techniques are possible, especially if only moderate hypotension is required, the mechanism of action of isoflurane is very appealing: it reduces arterial pressure by reducing the peripheral resistances, without reducing the output, unlike halothane or trinitrin. Moreover, as it is anaesthetic, it reduces the overall oxygen consumption, such that if there were a fall in output one could assume that it was related to the level of oxygen consumption. When there is no severe hypocapnia, isoflurane, quite unlike sodium nitroprusside, lowers cerebral oxygen consumption without affecting cerebral blood flow rate. It does however increase intracranial pressure, like all the other hypotensive agents used. It does not increase filling pressures and has no effect on blood gas movements, unlike sodium nitroprusside and trinitrin which increase filling pressures and the intrapulmonary shunt. It is not toxic either, unlike sodium nitroprusside. The expensiveness of the drug is balanced by its many advantages, all the more so as this cost can be reduced by using a filter-system for some cases (e.g. middle ear surgery), or by using some drug combinations which need yet to be defined. However, there exist some disadvantages which may, in fact, be due to experimental conditions: failure of induced hypotension, coronary ischaemia, doubtful cerebral protection in case of focal areas of ischemia, different degrees of organ vasodilation.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebrovascular Circulation↗
PubMed1988

Pharmacokinetics and haemodynamic effects of prolonged methohexitone infusion.

1. The use of continuous infusion anaesthesia has only been of interest since the development of short-acting, less cumulative and less toxic drugs. 2. This study aimed to compare pharmacokinetics and haemodynamic effects during and after long time methohexitone constant rate infusion. Sixteen patients were given either 60 or 90 micrograms kg-1 min-1 methohexitone during 14 h. Blood samples were taken hourly during this time and 12 h following the end of infusion. 3. Infusion period was analysed by a single exponential model; post-infusion time showed a three compartment model, the intermediate phase parameters corresponding to those of the infusion period. 4. Methohexitone was haemodynamically well tolerated; prolonged infusion decreases oxygen consumption, mainly by a decrease in oxygen demand. 5. Many patients remained unconscious for unacceptably long periods of time after post-operative sedation by methohexitone.

Hemodynamics↗
PubMed1988

Impact of surgical stress on the haemodynamic profile of isoflurane-induced hypotension.

It has been suggested that stimulation of adrenoreceptors could be responsible for some of the haemodynamic effects of isoflurane. But there are no solid data demonstrating the role of sympatho-adrenal stimulation induced by pain during isoflurane administration. The impact of surgical stress on the haemodynamic profile of isoflurane-induced hypotension has been investigated in 28 patients (47-76 years), scheduled for total hip arthroplasty. After premedication with morphine hydrochloride (0.1 mg/kg), patients were randomly assigned to receive either no fentanyl (control group) or fentanyl (5 micrograms/kg before tracheal intubation, 5 micrograms/kg before skin incision, and 2 micrograms/kg each 15 min during the 1st hour). Isoflurane was given to maintain mean arterial blood pressure in the range 6.7-8 kPa in both groups. Haemodynamic data and blood samples for determination of plasma renin activity (PRA) and epinephrine (E) and norepinephrine (NE) levels were collected before and during hypotension. The fentanyl group and the control group differed significantly during hypotension: heart rate, cardiac index, oxygen consumption and E, NE and PRA were lower (P less than 0.01) in the fentanyl group than in control group. Fentanyl lowered the required concentration of isoflurane to achieve the same degree of hypotension (end-tidal concentration: 0.8 +/- 0.2% in the fentanyl group and 1.4 +/- 0.15% in the control group; P less than 0.001). Our results demonstrate that the cardiovascular effects of higher isoflurane concentrations in the absence of narcotic analgesia are counterbalanced by adrenergic stress stimulation of released epinephrine and norepinephrine. Among the likely reasons for catecholamine release during isoflurane administration, inadequate analgesia may be considered.

Aged↗
PubMed1987

Systemic haemodynamic and metabolic effects of deliberate hypotension with isoflurane anaesthesia or sodium nitroprusside during total hip arthroplasty.

Isoflurane (ISO) was examined as an alternative hypotensive agent to nitroprusside (SNP) in 16 patients (mean age: 60 years) anaesthetized for total hip arthroplasty. MAP was decreased to 50 per cent of the awake level by infusion of SNP in Group I (n = 8) and with ISO in Group II (n = 8). Fentanyl (10-16 micrograms X kg-1) was administered to both groups. Haemodynamic measurements were repeated in the lateral position before, during and after hypotension. Polygeline and fresh frozen plasma were infused throughout the study period in volumes sufficient to maintain pulmonary capillary wedge pressure in the 7-9 mmHg range. The MAP decrease was the same in both groups, as were perioperative blood replacement (mean 500 ml), and postoperative haematocrits. Total perioperative fluid replacement was higher (p less than 0.01) in Group I (mean 2500 ml) than in Group II (mean 1300 ml). Venous tone was more affected by SNP than by ISO. ISO decreased the systemic vascular resistance index and oxygen consumption (VO2) without any change in CI or in Qs/Qt, in contrast to SNP which increased CI, VO2 and Qs/Qt.

Adult↗
PubMed1987

[Effect of propofol on left ventricular function in the coronary patient. Combined isotopic and hemodynamic studies].

The present study investigated the effects of propofol (P) as sole anaesthetic agent of left ventricular (LV) function using gated radionuclide ventriculography (RNV) in unpremedicated patients with chronic coronary arterial disease (CAD). After informed consent, seven ASA 111 patients (51-74 yr) undergoing major urologic surgery took part in this study. All patients suffered from documented angina pectoris secondary to CAD. None gave a history of congestive heart failure or valvular heart disease. No patients were premedicated, but all received their chronic medications (nifedipine and isosorbide) up to and including the morning of surgery. The study was performed in the Nuclear Medicine Laboratory just before surgery. Heart rate (HR) was obtained from standard limb lead II of the ECG. A 7.5 F thermodilution Swan-Ganz catheter and a radial artery cannula were inserted under local anaesthesia. All patients were studied by RNV using red blood cells (RBC) labelled in vivo with 99m-technetium (Tc). A first RBC-Tc preparation containing 2-3 mCi f Tc was counted 10 cm from a gamma-camera. A first-pass study was carried out in the left anterior oblique position following the bolus i.v. injection of the source, allowing the evaluation of the isotopic dilution cardiac output (COiso) and the attenuation factor (F). Then, a second RBC-Tc preparation containing 20-25 mCi of Tc was injected intravenously. At equilibrium, 16 ECG-synchronized frames were acquired by computer for processing. Mean end-diastolic (ED) and end-systolic (ES) counts, left ventricular-end diastolic and systolic areas and ejection fraction (EF) were calculated every 1.5 min.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1987

[Hemodynamic monitoring in microneurosurgical excision by sub- and retro-sinus approach in seated position in acoustic neurinoma].

Haemodynamic data (thermodilution Swan-Ganz catheter and radial artery cannula) were collected in 17 patients (52.4 +/- 8 yr) during retrosigmoid approach for removal of an acoustic tumour in the seated position. Measurements were made before stimulation of posterior fossa structures (period 1) and during tumour dissection along the brain stem (period 2). Significant increases in systolic, diastolic and mean blood pressures, in pulmonary capillary wedge pressure, in cardiac index and in stroke index were observed during period 2, whereas heart rate, right atrial pressure and systemic vascular resistances were unaffected. The greater the size of the tumour and the difficulties in dissection, the greater were these intraoperative haemodynamic changes. In addition, the pulmonary arterial blood temperature and the noradrenaline plasma concentrations (double isotope enzymatic assay) increased significantly during period 2. In conclusion, the prolonged microsurgical technique of acoustic tumour dissection through the retrosigmoid approach may modify left ventricular loading conditions and may lead to pulmonary oedema, even if intravascular volume expansion was minimal and ventricular function was near normal.

Adult↗
PubMed1987

Vecuronium and atracurium in patients with end-stage renal failure. A comparative study.

Twenty patients with end-stage renal failure, undergoing kidney transplantation, were assigned randomly to receive either vecuronium or atracurium under evoked twitch tension control. The cumulative-dose technique was used to obtain 95% twitch depression (vecuronium: initial bolus 15 micrograms kg-1, increments 6 micrograms kg-1; atracurium: initial bolus 100 micrograms kg-1, increments 40 micrograms kg-1). Using ED95 values derived from the log-probit dose-response curves, vecuronium was 4.6 times more potent than atracurium. The durations of action of the initial cumulative-doses (from end of injection of the last increment to 25% recovery) were 11.1 +/- 3.3 min for vecuronium and 16.2 +/- 3.9 min for atracurium (P less than 0.05). In terms of duration of action of the maintenance doses (vecuronium one-quarter of the total incremental dose; atracurium one-third) some cumulation was observed with vecuronium (interaction time X treatment; cumulation ratio 1.46 +/- 0.31 v. 0.98 +/- 0.10 for atracurium, P less than 0.001). After 2 h of surgery, the mean recovery times (25% to 75% twitch height) did not differ (18.5 +/- 2.8 min and 16.7 +/- 4.4 min). It is concluded that vecuronium might be less safe than atracurium in patients with end-stage renal failure undergoing prolonged operations.

Adult↗
PubMed1987

A reappraisal of norepinephrine therapy in human septic shock.

The effectiveness and safety of iv infused norepinephrine (0.5 to 1 microgram/kg X min) were evaluated in 12 hyperdynamic vasodilated septic patients, who remained hypotensive despite iv volume expansion and antimicrobial and dopamine therapy. During norepinephrine infusion, mean arterial pressure and systemic vascular resistance index increased (p less than .001) and heart rate decreased (p less than .02). Cardiac index either increased or was unchanged in ten patients and decreased slightly in the remaining two patients. Urine flow increased (p less than .01) and was more than 0.5 ml/min when a critical renal perfusion pressure was reached if renal damage was not overwhelming. We conclude that norepinephrine may improve arterial BP and urine flow when volume replacement and dopamine therapy have failed to reverse the hypotension of septic shock.

Adult↗
PubMed1987

Hemodynamic effects of continuous norepinephrine infusion in dogs with and without hyperkinetic endotoxic shock.

We compared, at constant preload maintained by polygeline (gelatin) infusion, the hemodynamic effects of continuous infusion of norepinephrine (0.5, 1, and 1.5 micrograms/kg X min) in anesthetized dogs with and without hyperdynamic endotoxic shock. In both groups, norepinephrine infusion increased systolic, diastolic and mean aortic BP, cardiac index, stroke index, index of myocardial contractility, and mean pulmonary artery pressure. No significant change in right atrial pressure, left ventricular end-diastolic pressure, heart rate, systemic vascular resistance, or pulmonary vascular resistance was observed. Oxygen consumption index and oxygen extraction ratio remained unchanged. Increases in systolic aortic BP were dose-related, whereas maximal effects on other variables were obtained at 0.5 to 1 microgram/kg X min. The rise in aortic pressure resulted from an increased cardiac index but not from an increased systemic vascular resistance. Stroke index increased as contractility improved. The slight alpha-adrenergic effect of continuous, low-dose norepinephrine infusion did not impede the beneficial effects of the marked beta-adrenergic stimulation on cardiac function. The combination of these two effects improved hemodynamic disturbances of hyperdynamic endotoxic canine shock.

Animals↗
PubMed1987

Peroperative hypothermia prevention.

Peroperative thermal losses were studied in 28 patients (mean age 64 years) operated for a total hip prosthesis under controlled hypotension. The patients were split into four groups according to the method of hypothermia prevention used: reflective blanket, heating humidifier of inhaled gases, combination of both techniques or no prevention at all. The thermal loss was quicker and more intense in the last group. The superiority of one prevention method over another could not be demonstrated, but the urgency of its implementation proved to be essential.

Humans↗
PubMed1986

Hypotensive actions of diltiazem and nitroprusside compared during fentanyl anaesthesia for total hip arthroplasty.

The potential for inducing hypotension during fentanyl anaesthesia by administering either diltiazem (n = 7) or sodium nitroprusside (n = 7) was investigated during total hip arthroplasty. Haemodynamic variables were obtained in the lateral position before, during and after administration of the hypotensive agent. Diltiazem 0.15 mg X kg-1 given as an IV bolus followed by a 12.5 +/- 3 micrograms X kg-1 X min-1 continuous infusion decreased mean arterial pressure (MAP) from 77 +/- 11 mmHg to 63 +/- 16 mmHg (p less than 0.05) while other haemodynamic parameters showed only minor and insignificant changes. Hypotension continued for at least 30 min after the cessation of diltiazem. With sodium nitroprusside MAP decreased immediately from 81 +/- 11 mmHg to 59 +/- 9 mmHg (p less than 0.01) and rapidly returned to its control value after cessation of the infusion. CI and Qs/Qt rose significantly (p less than 0.05) while the systemic vascular resistance index (SVRI) (p less than 0.01) and pulmonary vascular resistance index (PVRI) (p less than 0.05) fell significantly. The haemodynamic profile was significantly different between hypotensive agents for MAP (p less than 0.02), heart rate (HR) (p less than 0.01), SVRI (p less than 0.05), and PVRI (p less than 0.05). HR was lower with diltiazem than with nitroprusside. A bradycardia less than 50 beats/min was observed in five patients in the diltiazem group. MAP, SVRI and PVRI were lower with nitroprusside than with diltiazem. Diltiazem can induce and maintain moderate hypotension without tachycardia and decreased cardiac output in humans during fentanyl anaesthesia but the modulation of the level of arterial pressure and the depression of atrioventricular conduction are unpredictable.

Aged↗