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Biomedical subjects

M Pinaud

Publications and source records attributed to M Pinaud.

At least 73 records · Page 4Linked to original sources
PubMed1993

[Is urapidil a venodilator?].

This study aimed to assess and compare the effects of urapidil and clonidine on right ventricular volumes and function in 20 physical status ASA III patients, with a borderline untreated essential hypertension and with or without chronic coronary artery disease. The patients were randomly assigned to two equal groups to receive either urapidil (0.4 mg.kg-1) or clonidine (2.5 micrograms.kg-1). Neither patient had congestive heart failure, valvular heart disease, previous myocardial infarction, nor was any being treated with beta-blocking agents or with amiodarone. Usual anti-anginal medication (nifedipine and isosorbide) was maintained up to the time of the procedure. Monitoring was obtained from ECG, Swan-Ganz catheter fitted out with a fast response-thermistor, and radial artery cannula. Blood samples were withdrawn for plasma atrial natriuretic factor determination. Thirty minutes after catheter insertion, baseline data were collected in supine and 45 degrees head-up tilt positions. Following urapidil or clonidine i.v. injection, three series of measurements (3, 8 and 13 min) were made in supine and tilt positions according to a randomized sequence. The two groups were similar with regard to age, weight, height, coronary artery disease and treatment. Urapidil and clonidine elicited a similar decrease in mean arterial pressure of 14% in supine position and 20% in head-up tilt position, combined with an exclusive decrease in systolic index i.e. not associated with a change in peripheral vascular resistances. Despite the decrease in arterial pressure, heart rate remained unchanged. Right ventricular ejection fraction was maintained after both urapidil and clonidine, however end-diastolic and end-systolic volumes decreased, with no modification by tilting.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial Natriuretic Factor↗
PubMed1993

Plasma concentrations of midazolam after i.v., nasal or rectal administration in children.

Midazolam is used frequently for premedication in children, preferably by non-parenteral administration. We have compared plasma concentrations of midazolam after nasal, rectal and i.v. administration in 45 children (aged 2-9 yr; weight 10-30 kg) undergoing minor urological surgery. General anaesthesia consisted of spontaneous respiration of halothane and nitrous oxide in oxygen via a face mask. After administration of atropine and fentanyl i.v., children were allocated randomly to receive midazolam 0.2 mg kg-1 by the nasal, rectal or i.v. route. In the nasal group, children received 50% of the dose of midazolam in each nostril. In the rectal group, midazolam was given rectally via a cannula. Venous blood samples were obtained before and up to 360 min after administration of the drug. Plasma concentrations of midazolam were measured by gas chromatography and electron capture detection. After nasal and rectal administration, midazolam Cmax was 182 (SD 57) ng ml-1 within 12.6 (5.9) min, and 48 (16) ng ml-1 within 12.1 (6.4) min, respectively. Rectal administration resulted in smaller plasma concentrations. In the nasal group, a plasma concentration of midazolam 100 ng ml-1 occurred at about 6 min. After 45 min, the concentration curves after i.v. and nasal midazolam were similar.

Administration, Intranasal↗
PubMed1993

Diltiazem reduces the dose requirement for nitroprusside-induced hypotension.

The efficacy of diltiazem, a calcium channel blocker, for reducing the dose requirement for nitroprusside-induced hypotension was studied in 20 healthy patients during spine fusion for scoliosis. Anesthesia included methohexital (3 mg/kg followed by 3 mg.kg-1.h-1 intravenously), nitrous oxide, and alfentanil (40 micrograms/kg, followed by 0.7 microgram.kg-1.min-1 intravenously). Patients were assigned randomly to two groups, receiving either nitroprusside alone or nitroprusside and diltiazem (bolus of 80 micrograms/kg with two consecutive infusions of 4.5 micrograms.kg-1.min-1 during the first 30 min and then 1.3 micrograms.kg-1.min-1). Nitroprusside was used to maintain mean arterial pressure at 55-60 mm Hg in both groups. Hypotension was obtained in similar times, 4 min in the group receiving nitroprusside alone (range, 1-8 min) and 2 min in the group receiving nitroprusside and diltiazem (range, 1-8 min). Nitroprusside administration lasted 186 +/- 17 min (mean +/- SEM) in the group receiving nitroprusside alone and 214 +/- 26 min (mean +/- SEM) in the other group (NS). After hypotension, arterial blood pressure returned to its initial value in a time of 7 min in the group receiving nitroprusside alone (range, 5-9 min) and 9 min in the group receiving nitroprusside and diltiazem (range, 7-13 min) (NS). Cumulative doses of nitroprusside were larger in the group receiving nitroprusside alone (0.47 +/- 0.07 mg/kg; mean +/- SEM) than in the other group (0.24 +/- 0.05 mg/kg; mean +/- SEM) (P < 0.01). Significant increase in plasma thiocyanate concentration, cardiac index, and heart rate was observed only in the group receiving nitroprusside alone, but no intergroup differences were found.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

[Hemodynamic effects of bathing in severe burnt patients].

Repeated water immersion is currently used in France in the treatment of severe burn injury. A prospective study was carried out to assess the haemodynamic effects of immersing such patients in a half sitting position in water, the temperature of which was kept at 35 degrees C. The burn exceeded 50% of body surface area (BSA), with at least 30% being third degree burns. The study was carried out during the first bath, three days after the injury. The patients were immersed up to the clavicles. They were sedated with 2 mg.h-1 of both flunitrazepam and phenoperidine, and were mechanically ventilated. The following haemodynamic parameters were monitored: heart rate, arterial blood pressure (the transducer being level with the arterial catheter), right atrial and pulmonary arterial pressures (the transducer being level with the right atrium, level which had been marked on the chest before immersion and placed two intercostal spaces higher after immersion because of the change in position of the heart). The cardiac output was measured using the thermodilution method. The patient's temperature was monitored with the thermistance of the Swan-Ganz catheter. Values were obtained before immersion, after 15 and 30 minutes of immersion, and 5 minutes after the end of the bath. Nine patients were included, 2 women and 7 men, aged between 24 and 45 years, weighing 73.7 kg on average. Burn size was 78% of BSA (range 64 to 95%). Water immersion was maintained for 34 +/- 3 min. The right atrial, mean pulmonary arterial, and wedge pressures, and the cardiac and systolic indices increased.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Long-term hypotensive technique with nicardipine and nitroprusside during isoflurane anesthesia for spinal surgery.

Short-term infusion of nicardipine can be used to induce deliberate hypotension but may result in plasma drug accumulation. To assess long-term nicardipine administration for deliberate hypotension in 10 patients in a moderately hemodiluted state who were undergoing spinal surgery, hemodynamics and plasma nicardipine concentrations were concomitantly measured before and 20, 80, and 140 min after starting nicardipine, at drug discontinuation, and 20 and 80 min later. A dose of 6.2 +/- 0.9 mg (mean +/- SEM) of nicardipine was initially required to obtain mean arterial blood pressures at 55-60 mm Hg. Maintenance doses of nicardipine were 3-5 mg/h. The duration of nicardipine administration was 270 +/- 20 min (mean +/- SEM). Hypotension was associated with decreased systemic and pulmonary vascular resistances, increased cardiac index, and decreased arteriovenous difference in O2 contents. Only two patients required homologous blood transfusion. Plasma nicardipine concentrations peaked at 110 +/- 21 ng/mL (mean +/- SEM) and then decreased to 38 +/- 11 ng/mL (mean +/- SEM) without changes in arterial blood pressure. After vasodilator discontinuation, hypotension was observed during a mean time of 43 min (range 27-88 min) despite plasma concentrations less than 20 ng/mL. No relationship was found between plasma nicardipine concentrations and hemodynamics. These findings suggest that an increasing effect of nicardipine over time may occur during prolonged administration. Because the reasons for this hysteresis remain unclear, use of nicardipine infusion during major surgery and anesthesia requires particular caution.

Adult↗
PubMed1991

[Effects of Diprivan on cerebral blood flow, intracranial pressure and cerebral metabolism in head injured patients].

The effects of propofol on cerebral blood flow, intracranial pressure (ICP) and cerebral oxygen consumption (CMRO2) were assessed in ten severely head-injured patients undergoing surgery for limb fractures. The patients, aged between 15 and 40 years, were in deep coma, scored 6-7 on the Glasgow coma score. They were mechanically ventilated and sedated with 1 mg.h-1 phenoperidine. Anaesthesia was carried out with a 2 mg.kg-1 intravenous bolus of propofol, immediately followed by a 150 micrograms.kg-1.min-1 infusion, which lasted for a mean time of 41.4 +/- 7.3 min. Data were collected 5 min before any propofol was given, 15 min after the start of the infusion, and 15 min after its end. A radial artery cannula, a 7.5 Fr thermodilution flow-directed pulmonary arterial catheter, a cerebral intraventricular catheter and a catheter in the jugular venous bulb were used for this purpose. Carotid arterial injection of 133Xenon was used to determine regional cerebral blood flow (rCBF). Anaesthetic blood concentrations of propofol (3 to 5 micrograms.ml-1) were associated with a decrease in all the parameters studied: cerebral perfusion pressure, from 82 +/- 14 mmHg to 59 +/- 7 mmHg (p less than 0.001); rCBF, from 35 +/- 6 ml.100 g-1.min-1 to 26 +/- 5 ml.100 g-1.min-1 (p less than 0.01); ICP from 11.3 +/- 2.6 mmHg to 9.2 +/- 2.5 mmHg (p less than 0.001); CMRO2 from 1.63 +/- 0.38 mlO2 +/- 100 g-1.min-1 to 1.18 +/- 0.38 mlO2.100 g-1.min-1 (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1991

[Hemodynamic effects of dobutamine in hyperkinetic septic shock treated with norepinephrine].

A prospective study of the haemodynamic effects of dobutamine was carried out in six men and four women suffering from hyperkinetic septic shock, already treated with noradrenaline and dopamine. All ten patients had septic shock, defined as a mean arterial blood pressure of less than 70 mmHg and an urine output under 15 ml.h-1, persisting despite fluid loading, associated with positive blood cultures, increased white blood cell counts, and a septic area. Initial treatment consisted in fluid loading, so as to increase cardiac output whilst keeping pulmonary wedge pressure (Ppw) between 8 and 10 mmHg. Dopamine was then added, up to a dose of 15-20 micrograms.kg-1.min-1, in an attempt to improve coronary and renal blood flows. In patients in whom this failed, the amounts of dopamine were then decreased, down to 3 micrograms.kg-1.min-1, and replaced by noradrenaline. When patients had as steady cardiac index (CI) greater than 3 l.min-1.m-2 and a systemic arterial resistance index (RsaI) of less than 1,800 dyn.s.cm-5.m-2 for more than 60 min, they were included in the protocol. Dopamine was then replaced by increasing doses of dobutamine (0, 5, 7.5, 10, 15 and again 0 micrograms.kg-1.min-1). The usual haemodynamic parameters were measured and calculated once a steady state had been obtained at each dose (within 20 to 30 min). Ppw was kept between 8 and 10 mmHg by fluid loading with a 4% albumin solution. At the beginning of the study, patients had a mean blood pressure of 78 +/- 6 mmHg, a CI of 4.8 +/- 1.5 l.min-1.m-2 and a RsaI of 1,285 +/- 341 dyn.s.cm-5.m-2 RsaI.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

[Comparative effects of diazepam, ranitidine , sodium citrate and enprostil on pH and gastric volume in preanesthetic medication].

A study was designed to assess the efficacy of oral premedication with diazepam or enprostil in preventing the gastric aspiration syndrome in fasted patients scheduled for elective surgery, and to compare the results with those obtained with ranitidine and sodium citrate. The study included 120 consecutive patients undergoing urological or plastic surgery, randomly assigned to four groups of 30. Two hours before anaesthesia, the patients from three groups were given, with 30 ml of water, either 10 mg diazepam, or 150 mg ranitidine, or 35 micrograms enprostil. Those in the fourth group were given 30 ml of 0.5 M sodium citrate, ten minutes before induction. Anaesthesia consisted in the administration of thiopentone, fentanyl, vecuronium and nitrous oxide in oxygen. After endotracheal intubation, a gastric tube was inserted. The stomach fluid content was completely aspirated, and then again 60 and 120 min after induction, as well as at the end of surgery. Age, weight and duration of surgery were comparable in the four groups. Mean pH in the diazepam group was much lower than that in the other groups, both just after induction (2.3 +/- 1.54; p less than 0.001 vs. ranitidine and sodium citrate; p less than 0.01 vs. enprostil) and at the end of surgery (3.2 +/- 2.03; p less than 0.01 vs. ranitidine and sodium citrate; p less than 0.05 vs. enprostil). There was more than 0.4 ml.kg-1 gastric juice in the sodium citrate group.(ABSTRACT TRUNCATED AT 250 WORDS)

Antacids↗
PubMed1991

[Effects of intravenous clonidine on postoperative shivering].

A study was designed to assess the possible effects of intravenous clonidine on postoperative shivering. Fifty patients undergoing spinal fusion under isoflurane anaesthesia were randomly assigned to two groups (n = 25). Patients in one group were given intravenous clonidine (5 micrograms.kg-1 during the first hour, and 0.3 microgram.kg-1.h-1 thereafter) or placebo. Shivering intensity (rated from 0 to 2) and pulmonary artery blood temperature (theta) was recorded every ten minutes for two hours. Haemodynamic and metabolic data were obtained by way of a Swan-Ganz catheter prior to administering the test drug, and then after 1 and 2 hours. On arrival at the recovery room, theta was 36.2 +/- 0.3 degrees C in the clonidine group, and 36.5 +/- 0.2 degrees C in the placebo group. There were no significant differences in shivering between the two groups. Clonidine significantly decreased blood pressure, heart rate, cardiac output and whole body oxygen consumption. The patients in these series were free from any cardiac disease. Further studies are required to assess the possible beneficial effects of clonidine on postoperative oxygen consumption in patients suffering from heart failure.

Adult↗
PubMed1991

Ketamine and midazolam neurotoxicity in the rabbit.

Ketamine and midazolam can produce analgesia following intrathecal administration in rabbits. However, neurotoxicity studies are required before these agents can be considered safe for clinical use. The aim of this study was to evaluate by histologic and blood-brain barrier (BBB) studies whether ketamine or midazolam could be used as an alternative to local anesthetics or opioids to produce spinal analgesia. Forty white New Zealand rabbits were randomly assigned to four groups of 10. In the conscious animal, 0.3 ml 0.9% saline solution, 1% lidocaine, 1% ketamine, or 0.1% midazolam was intrathecally injected intracisternally using a modification of the technique of Yaksh et al. Light and fluorescence microscopy were performed on transverse spinal cord sections by a neuropathologist unaware of the administered agents. All spinal cord section slides were scored within four zones: upper cervical, lower cervical, median thoracic, and lumbar segments. Spinal cord homogeneous lesions with higher scores than those of lidocaine-treated animals were considered abnormal. The BBB study showed evidence of neurotoxicity for ketamine, whereas light microscopy indicated no significant differences in comparison with saline and lidocaine. Midazolam-treated rabbits showed significant changes in both BBB and light microscopy studies. In view of these results, the intrathecal use of midazolam should be avoided in humans. Lesions observed following ketamine suggest the need for further experimental studies of the solvent and different ketamine enantiomers to establish definitively the safety of intrathecal free ketamine in humans.

Animals↗
PubMed1991

Postoperative analgesia by intravenous clonidine.

Clonidine, an alpha 2 adrenoreceptor agonist, has nonopiate antinociceptive properties, which might be an alternative for postoperative analgesia free of opioid-induced side effects. To document the analgesic properties of intravenous clonidine during the postoperative period, 50 ASA physical status 1 patients, immediately after spinal fusion, were randomly assigned to two groups, blindly administered either clonidine (5 micrograms/kg infused the 1st h and then 0.3 microgram-1.kg-1.h-1 during 11 h) or a placebo. A visual analog scale graded from 0 (no pain) to 100 mm was used to assess pain before clonidine or placebo administration (T0), at the end of the loading dose (T1) and then every 2 h (T3, T5, T7, T9, and T11). Morphine (0.1 mg/kg) was administered intramuscularly after each pain measurement if the score was greater than 50 mm. No morphine was given at T0. Hemodynamics, blood gases and plasma clonidine concentrations were measured each time the pain score was measured. The pain score decreased from 42 +/- 5 to 26 +/- 3 mm (mean +/- standard error) in the clonidine group whereas it was unchanged in the placebo group despite a greater morphine requirement (dose for each patient: 3.8 +/- 1 vs. 10.8 +/- 1.2 mg). Clonidine delayed the onset of pain and the first request for morphine injection. Mean arterial pressure decreased to 74 +/- 2 mmHg in the clonidine group (-26 +/- 2 vs. -15 +/- 2% in the placebo group at T11) despite a significant increase in the cumulative fluid volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Clonidine↗
PubMed1991

Effects of oral clonidine premedication and postoperative i.v. infusion on haemodynamic and adrenergic responses during recovery from anaesthesia.

The effects of clonidine, a central alpha 2-adrenoreceptor agonist, on haemodynamic and catecholamine changes were assessed during emergence from anaesthesia, a period which is associated with increased sympathetic nervous discharge, hypertension and tachycardia. According to a double-blind randomized design, 32 patients received either clonidine, preoperatively given by oral route (3.5 micrograms.kg-1) and postoperatively by i.v. infusion (0.3 microgram.kg-1.h-1), or a placebo. Perioperative management was similar in both groups. Measurements were made in the recovery room, before starting clonidine or placebo infusions for evaluation of clonidine premedication, and then during infusion as follows: when core temperature reached 37 degrees C; then 2 h, and 6 h later. Prior to starting infusions, mean blood pressure (88 +/- 15 vs 103 +/- 14 mmHg) (11.7 +/- 2.0 vs 13.7 +/- 1.9 kPa), heart rate (67 +/- 8 vs 87 +/- 17 beats.min-1) and plasma norepinephrine levels (462 +/- 393 vs 615 +/- 361 pg.ml-1) were lower in the clonidine group. Only at the latest measurement (6 h after core temperature reached 37 degrees C) did clonidine elicit significant effects. The values during clonidine infusion compared to placebo were at this time: mean blood pressure (73 +/- 10 vs 86 +/- 13 mmHg) (9.7 +/- 1.3 vs 11.5 +/- 1.7 kPa), heart rate (71 +/- 6 vs 93 +/- 13 beats.min-1) and plasma norepinephrine levels (240 +/- 224 vs 451 +/- 111 pg.ml-1). Our results suggest that: 1) preoperative clonidine may improve the haemodynamic profile associated with anaesthetic discontinuation, but 2) i.v. infusion (0.3 microgram.kg-1.h-1) did not prolong this effect during the early postoperative period in the face of the sympathetic nervous discharge of recovery.

Administration, Oral↗
PubMed1991

Deliberate hypotension with nicardipine or nitroprusside during total hip arthroplasty.

To induce deliberate hypotension during anesthesia, nicardipine was administered to patients undergoing total hip arthroplasty and was randomly compared with nitroprusside. Hemodynamic measurements were performed before and 10, 20, 30, and 60 min after starting to administer either nicardipine (n = 12) or nitroprusside (n = 12) (B, T1, T2, T3, and T4, respectively); at the end of drug infusion (T5); and 10, 20, and 60 min later (T6, T7, and T8, respectively). Plasma renin activity and catecholamine levels were measured at B, T1, T5, T6, and T7. In addition, plasma nicardipine concentration was measured in five patients at T1, T2, T5, T7, and T8. As with nitroprusside, nicardipine administration (1-3 micrograms.kg-1.min-1, after a titration dose of 4.7 +/- 1.5 mg) resulted in hypotension (up to -34% +/- 3%), a decrease in systemic vascular resistances (up to -49% +/- 4%), and increases in heart rate (up to +17% +/- 6%), cardiac index (up to +37% +/- 8%), plasma norepinephrine (up to +63% +/- 17%) and epinephrine (up to +232% +/- 68%) levels, and plasma renin activity (up to +336% +/- 207%). Ten and 20 minutes after discontinuation of the hypotensive drug, nicardipine led to persistent vasodilation and hypotension, which differed significantly from the hypertensive rebound observed after nitroprusside discontinuation, despite a similar increase in plasma renin activity and catecholamine levels. Our results indicate that after the infusion was terminated, the nicardipine-induced vasodilation was opposed to the vasoconstrictive effects of angiotensin II and catecholamines, thus avoiding hypertensive rebound.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗