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Biomedical subjects

Pierre Coriat

Publications and source records attributed to Pierre Coriat.

50 records · Page 3Linked to original sources
PubMed2002

Detection of brain death onset using the bispectral index in severely comatose patients.

OBJECTIVES: To evaluate the accuracy of bispectral index (BIS) monitoring for the diagnosis of brain death in severely comatose patients. DESIGN: A prospective study in an intensive care unit of a university hospital. POPULATION: Fifty-six severely comatose patients (Glasgow Coma Score < or = 5) admitted to the ICU mainly because of intracerebral hemorrhage, head injury, or postanoxic coma. METHODS: BIS was recorded continuously during the hospitalization in the ICU. Where necessary, clinical brain death was confirmed by EEG or cerebral angiography. MEASUREMENTS AND RESULTS: Twelve patients were already clinically brain dead at the time of admission, and their individual BIS values were 0. In each of these 12 patients brain death was thereafter confirmed by EEG or cerebral angiography. Forty-four patients were not clinically brain-dead at the time of admission, and their individual BIS values were between 20 and 79. Twenty-seven of these patients became brain-dead, and their individual BIS values dropped to 0 in a few hours to a few days. In these 27 patients EEG or cerebral angiography was performed after the BIS value decreased to 0 and confirmed brain death in all cases. Seventeen patients who did not become brain dead during their hospitalization in the ICU had persistent electrocerebral activity on EEG, and their average BIS values remained above 35. CONCLUSION: BIS can be used in severely comatose patients as an assessment of brain death onset, enabling appropriate scheduling of either EEG or cerebral angiography to confirm brain death.

Brain Death↗
PubMed2002

The effect of universal leukodepletion of packed red blood cells on postoperative infections in high-risk patients undergoing abdominal aortic surgery.

UNLABELLED: We evaluated, by using a before-and-after study, the influence of leukoreduction by filtration on postoperative infections and adverse outcomes in patients undergoing elective major aortic surgery. From January 1995 to October 2000, all patients who underwent elective abdominal aortic surgery were included in the analysis. Before the introduction of systematic leukodepletion of packed red blood cells (RBCs), on April 1, 1998, 192 patients received standard or buffy-coat-depleted packed RBCs. Then, 195 patients were transfused with exclusively filtered leukodepleted packed RBCs. No major significant difference was observed between the groups of patients with regard to preoperative cardiac and pulmonary status, anesthetic and surgical techniques, or transfusion policy. No significant difference in mortality was observed between the two groups. The incidence of postoperative infections was 31% (95% confidence interval, 25%--38%) in the Control group versus 27% (95% confidence interval, 21%--33%) in the Leukodepleted group; severe infectious complications and pneumonia were not significantly different between the two groups of patients. Cardiovascular and respiratory outcomes were not significantly different between the groups. Data from this study suggest that the effect of using leukodepleted RBC on postoperative infections is not of obvious importance. IMPLICATIONS: We evaluated the influence of leukocyte reduction by filtration of packed red blood cells (RBC) on postoperative infections and adverse outcomes in patients undergoing elective major aortic surgery by comparing two epochs with and without filtration. Data from this study suggest that the effect of using filtered RBC on postoperative infections is not of obvious importance.

Adult↗
PubMed2002

Terlipressin-ephedrine versus ephedrine to treat hypotension at the induction of anesthesia in patients chronically treated with angiotensin converting-enzyme inhibitors: a prospective, randomized, double-blinded, crossover study.

UNLABELLED: In patients chronically treated with angiotensin converting-enzyme inhibitors (ACEI), typically selected doses of ephedrine do not always restore arterial blood pressure when anesthesia-induced hypotension occurs. We postulated that the administration of terlipressin, an agonist of the vasopressin system, with ephedrine more effectively restores pressure in this setting than the administration of ephedrine alone. This prospective, randomized, cross-over, double-blinded study compared terlipressin combined with ephedrine (n = 19) with ephedrine alone (n = 21) in treating hypotension at the induction of anesthesia in 40 ACEI-treated patients undergoing hypotension (mean arterial blood pressure [MAP] <65 mm Hg or <30% of baseline value) after standardized anesthetic protocol (target-controlled IV anesthesia with propofol). Data are mean +/- SD. Patient characteristics, MAP, and heart rate before and after the induction of anesthesia during hypotensive episodes were not significantly different between the two groups. After the first bolus, MAP was significantly greater in the Terlipressin-Ephedrine group (72 +/- 12 mm Hg versus 65 +/- 8 mm Hg, P < 0.05). The occurrence of a second hypotensive episode (5% versus 71%, P < 0.001), the duration (2 +/- 1 min versus 3 +/- 1 min, P < 0.01) of hypotensive episodes, and the median dose of ephedrine (3 versus 6 mg, P < 0.05) were significantly less in the Terlipressin-Ephedrine group. In conclusion, terlipressin combined with ephedrine is more effective than ephedrine alone for treating anesthesia-induced hypotension in ACEI-treated patients. We conclude that this patient population with a partially blocked endogenous response to hypotension may be good candidates for successful use of a vasopressin analog to counteract intraoperative refractory hypotension. IMPLICATIONS: Vascular surgical patients chronically treated with drugs that inhibit the functioning of the renin-angiotensin system may experience hypotension unresponsive to conventional therapy. This double-blinded, cross-over study demonstrated that in these patients the use of a vasopressin analog, terlipressin given with ephedrine, was effective in reversing intraoperative systemic hypotension refractory to ephedrine.

Aged↗
PubMed2002

The paradoxical positive inotropic effect of sevoflurane in healthy and cardiomyopathic hamsters.

UNLABELLED: We investigated the effects of sevoflurane (0.7 to 3.6 vol%) on inotropy and lusitropy in left ventricular papillary muscles of healthy hamsters and genetically induced cardiomyopathic (strain BIO 14.6) hamsters in vitro (29 degrees C, pH 7.40, Ca(2+) 2.5 mM, stimulation frequency three per minute) under low (isotony) and high (isometry) loads. Sevoflurane induced a moderate positive inotropic effect in healthy hamsters (maximum unloaded shortening velocity and isometric active force at 3.6 vol%: 115% +/- 12% and 128% +/- 21% of baseline values, respectively; P < 0.01) and in cardiomyopathic hamsters (maximum unloaded shortening velocity and isometric active force at 3.6 vol%: 115% +/- 20% and 124% +/- 31% of baseline values, respectively; P < 0.05). This positive inotropic effect did not differ between healthy and cardiomyopathic hamsters, even when sevoflurane concentrations were corrected for minimum alveolar anesthetic concentration values in each strain, and was unchanged after alpha- and beta-adrenoceptor blockade. After calcium-channel blockade, this positive inotropic effect was abolished in healthy hamsters but enhanced in cardiomyopathic hamsters. In both strains, sevoflurane induced a moderate negative lusitropic effect under low and high loads. IMPLICATIONS: A paradoxical moderate positive inotropic effect of sevoflurane was observed in hamster ventricular muscle. This effect was likely related to calcium channel interaction, because after calcium-channel blockade, it was abolished in healthy hamsters and enhanced in cardiomyopathic hamsters.

Administration, Inhalation↗
PubMed2002

Aprotinin versus placebo in major orthopedic surgery: a randomized, double-blinded, dose-ranging study.

UNLABELLED: We conducted a prospective, multicenter, double-blinded, dose-ranging study to compare the risk/benefit ratio of large- and small-dose aprotinin with placebo after major orthopedic surgery. Fifty-eight patients were randomized into three groups: Large-Dose Aprotinin (4 M kallikrein inactivator unit [KIU] bolus before surgery followed by a continuous infusion of 1 M KIU/h until the end of surgery), Small-Dose Aprotinin (2 M KIU bolus plus 0.5 M KIU/h), and Placebo. Bleeding was measured and calculated. Bilateral ascending venography was systematically performed on the third postoperative day. Measured and calculated blood loss decreased in the Large-Dose Aprotinin group (calculated bleeding, whole blood, hematocrit 30%, median [range], 2,023 mL [633-4,113] as compared with placebo, 3,577 mL [1,670-21,758 mL]). The total number of homologous and autologous units was also significantly decreased in the Large-Dose Aprotinin group (2 U [0-5 U] as compared with placebo, 4 U [0-42 U]). No increase in deep vein thrombosis or pulmonary embolism was observed in the aprotinin groups. Large-dose aprotinin was safe and effective in dramatically reducing the measured and calculated bleeding and the amount of transfused red blood cell units after major orthopedic surgery. IMPLICATIONS: Large doses of aprotinin decrease blood loss and transfusion amount in major orthopedic surgery.

Adult↗
PubMed2002

Hemodynamic and hormonal responses to the sudden interruption of caval flow: insights from a prospective study of hepatic vascular exclusion during major liver resections.

UNLABELLED: Hepatic vascular exclusion (HVE) combines portal triad clamping and occlusion of the inferior vena cava. Although HVE has been performed for major liver resections during the last 2 decades, little is known about the mechanisms that explain its satisfactory hemodynamic tolerance. Consequently, we performed a comprehensive study of both hemodynamic and hormone responses to HVE. Twenty-two patients who underwent liver resection for secondary tumors developed in noncirrhotic livers were prospectively studied. Heart rate, arterial blood pressure, pulmonary artery pressure, mixed venous saturation, cardiac output, and left ventricular dimensions determined by transesophageal echocardiography were monitored in HVE patients. Blood concentrations of arginine vasopressin (AVP), epinephrine, norepinephrine, dopamine, and atrial natriuretic peptide and plasma renin activity (PRA) were measured before clamping; 5, 15, and 30 min after clamping; and 15 min after unclamping. Hemodynamic response to HVE was characterized by a significant (P < 0.05) decrease in left ventricular dimensions, fractional area change, and pulmonary artery pressure. We also observed a marked decrease in cardiac output (50%) and an increase in heart rate and systemic vascular resistance. After unclamping, there was peripheral vasodilation, assessed by a significant decrease in systemic vascular resistance from the preclamping value to unclamping. An acute and sustained increase in AVP and norepinephrine that returned to baseline after unclamping and the absence of modification in PRA concentrations were noted. The marked decrease in venous return that characterizes HVE is compensated for by an increase in vascular resistance secondary to an important activation of the AVP and sympathetic systems. The PRA system does not play an important role in maintaining arterial blood pressure during HVE. IMPLICATIONS: Hemodynamic and hormonal responses to the acute interruption of caval venous return to the heart were investigated in patients undergoing liver resection with hepatic vascular exclusion. A compensatory role for arginine vasopressin and sympathetic systems that provoked increased vascular resistance was demonstrated.

Aged↗
PubMed2002

Postoperative titration of intravenous morphine in the elderly patient.

BACKGROUND: Intravenous morphine titration is used to obtain rapid and complete postoperative pain relief. Whether this titration can be safely administered in the elderly patients remains a matter for debate. METHODS: Intravenous morphine titration was administered as a bolus of 2 (body weight < or = 60 kg) or 3 (body weight > 60 kg) mg. The interval between each bolus was 5 min. There was no limitation in the number of boluses given until pain relief or severe adverse effect occurred. The visual analog scale threshold required to administer morphine was 30 mm, and pain relief was defined as a visual analog scale score of 30 mm or less. Patients were divided into two groups: young and elderly (age > or = 70 yr) patients. Data were expressed as mean +/- SD. RESULTS: Eight hundred seventy-five patients (83%) were young and 175 patients (17%) were elderly. At the end of morphine titration, the visual analog scale score and the number of patients with pain relief were not significantly different between groups. The total dose of morphine per kilograms of body weight administered was not significantly different between groups (0.15 +/- 0.10 vs. 0.14 +/- 0.09 mg/kg, not significant). No significant differences were observed in the incidence of morphine-related adverse effects (13 vs. 14%, not significant), the number of sedated patients (60 vs. 60%, not significant), and the number of patients whose titration had to be stopped (2 vs. 2%, not significant). CONCLUSION: Intravenous morphine titration can be safely administered to elderly patients. Because titration is adapted to individual pain, the same protocol can be applied to young and elderly patients.

Adult↗
PubMed2002

Brachial plexus nerve block exhibits prolonged duration in the elderly.

BACKGROUND: Upper limb trauma occurs frequently in elderly patients for whom peripheral nerve blocks are often preferred for anesthesia. The characteristics of such regional blocks have, however, never been described in an elderly population. Therefore, the authors assessed prospectively the onset and duration of upper extremity peripheral nerve block (the mid-humeral block) in elderly and young patients undergoing emergency upper extremity surgery. METHODS: Consecutive patients aged > 70 yr or < 70 yr received a mid-humeral block with a small volume of ropivacaine, 0.75%. Five milliliters was injected onto each of the musculocutaneous, radial, ulnar, and median nerves. Time to complete sensory and motor block and durations of complete sensory and motor block were assessed. Results are shown as median and its 95% confidence interval. RESULTS: Median ages were 77 yr (95% CI, 72-81 yr) and 39 yr (95% CI, 27-46 yr) in the two groups. Both groups had similar times to complete sensory blockade. The elderly group had longer durations of complete sensory (390 min [range, 280-435 min] vs.150 min [range, 105-160 min]; P< 0.05) and motor (357 min [range, 270-475 min] vs. 150 min [range, 90-210 min]; P< 0.05) blockade. Duration of complete sensory block was significantly correlated with age (rho = 0.56; P< 0.05). CONCLUSIONS: Age is a major determinant of duration of complete motor and sensory blockade with peripheral nerve block, perhaps reflecting increased sensitivity to conduction failure from local anesthetic agents in peripheral nerves in the elderly population.

Adult↗
PubMed2002

Use of perflubron emulsion to decrease allogeneic blood transfusion in high-blood-loss non-cardiac surgery: results of a European phase 3 study.

BACKGROUND: This single-blind randomized study in general surgery evaluated the efficacy of perflubron emulsion (PFC) as an artificial oxygen carrier being used to augment preoperative acute normovolemic hemodilution to reduce and avoid transfusion of both allogeneic erythrocytes and erythrocytes from preoperative autologous donation compared with standard of care. METHODS: Subjects (N = 492) with hemoglobin concentrations of 12-15 g/dl undergoing noncardiac surgical procedures with 20 ml/kg or greater expected blood loss were randomized into two groups. Control patients were transfused intraoperatively at a hemoglobin concentration less than 8.0 +/- 0.5 g/dl or at protocol-defined, physiologic triggers. PFC-treated patients first underwent acute normovolemic hemodilution to hemoglobin of 8.0 +/- 0.5 g/dl, followed by dosing with perflubron emulsion (1.8 g/kg). When hemoglobin reached less than 6.5 +/- 0.5 g/dl, an additional 0.9-g/kg dose was given. PFC patients were transfused at hemoglobin less than 5.5 +/- 0.5 g/dl or at predefined physiologic triggers. After surgery, hemoglobin was maintained at 8.5 +/- 0.5 g/dl or greater in all patients until discharge. Efficacy endpoints included the number of allogeneic and preoperative autologous donation units transfused and the percentage of subjects avoiding transfusion. RESULTS: Both groups had similar hemoglobin concentrations at screening (13.5 +/- 1.0 g/dl) and at discharge: 10.8 +/- 1.2 g/dl (PFC) and 11.1 +/- 1.3 g/dl (control). At 24 h, more patients in the PFC group avoided allogeneic and preoperative autologous donation erythrocyte transfusions (53% vs. 43%, < 0.05), and fewer erythrocytes were transfused (1.5 +/- 4.8 vs. 2.1 +/- 3.9 units; median, 0 vs. 1 unit; P = 0.013). By day of discharge, these differences were not significant in the intent-to-treat population, but overall there were less allogeneic and preoperative autologous donation erythrocyte transfusions in the PFC group (696 vs. 846 units). In the protocol-defined target population (n = 330 subjects with blood loss > or = 20 ml/kg), significantly greater avoidance of any erythrocyte transfusion was maintained through day of hospital discharge (26% vs. 16% in the PFC and control groups, respectively; P < 0.05), and there was also a significant reduction in the number of erythrocyte units transfused (3.4 +/- 2.9 vs. 4.9 +/- 2.4 units; median 2 vs. 4 units; P < 0.001). Adverse events rates were similar in the PFC (86%) and control (81%) groups; however, more serious adverse events were reported in the PFC group (32%) than in controls (21%; P < 0.05). Overall mortality was 3%, and the difference between groups (PFC, 4% vs. controls, 2%) was not statistically significant. CONCLUSIONS: Augmented acute normovolemic hemodilution with PFC reduces transfusion needs in patients undergoing noncardiac surgical procedures with blood loss 20 ml/kg or greater.

Adult↗
PubMed2002

Myocardial effects of halothane and isoflurane in senescent rats.

BACKGROUND: Aging is associated with marked alterations in myocardial contraction and relaxation, whereas halogenated anesthetics depress myocardial contractility. However, their effects on aging myocardium are unknown. METHODS: Mechanical variables of left ventricular papillary muscles from adult and senescent rats (29 degrees C; pH 7.40; Ca2+ 1.0 or 0.5 mM; stimulation frequency, 12 pulses/min) were studied. The expression of genes coding for the alpha and beta-myosin heavy chain (MHC) and Ca2+ -ATPase of the sarcoplasmic reticulum (SR) were studied. The effects of halothane and isoflurane were studied. The inotropic effects were compared under low and high loads, using the maximum unloaded shortening velocity (Vmax) and maximum isometric active force (AF). The lusitropic effects were compared in isotonic and isometric conditions. RESULTS: Senescent rats had a decrease in contraction and relaxation velocities, associated with a reexpression of beta-MHC mRNAs and a decrease in SR Ca2+ -ATPase mRNAs. Halothane induced a lower negative inotropic effect in senescent rats (1.5 vol%, AF: 53 +/- 14% vs. 39 +/- 12% of baseline values; P < 0.01) whereas isoflurane induced a similar negative inotropic effect (1.5 vol%, AF: 81 +/- 7% vs. 87 +/- 7% of baseline values; NS). Halothane induced a negative lusitropic effect in isotonic conditions in adult, but not in senescent, rats. CONCLUSIONS: The inotropic and lusitropic effects of halothane were less important in senescent than in adult rats, whereas the effects of isoflurane were similar. These differences are probably related to differences in SR function and in the effects of halogenated anesthetics on the SR.

Aging↗
PubMed2002

Effects of postnatal maturation on energetics and cross-bridge properties in rat diaphragm.

The effects of maturation on cross-bridge (CB) properties were studied in rat diaphragm strips obtained at postnatal days 3, 10, and 17 and in adults (10-12 wk old). Calculations of muscle energetics and characteristics of CBs were determined from standard Huxley equations. Maturation did not change the curvature of the force-velocity relationship or the peak of mechanical efficiency. There was a significant increase in the total number of CBs per cross-sectional area (m) with aging but not in single CB force. The turnover rate of myosin ATPase increased, the duration of the CB cycle decreased, and the velocity of CBs decreased significantly only after the first week postpartum. There was a linear relationship between maximum total force and m (r = 0.969, P < 0.001), and between maximum unloaded shortening velocity and m (r = 0.728, P < 0.001). When this study in the rat and previous study in the hamster are compared, it appears that there are few species differences in the postnatal maturation process of the diaphragm.

Actomyosin↗
PubMedDate not supplied

An unusual case of painful phantom-limb sensations during regional anesthesia.

OBJECTIVE: The objective of this article is to describe a late-onset phantom-limb pain during a continuous analgesic popliteal nerve block after foot surgery and its alleviation and recurrence when stopping and resuming the local anesthetic infusion. CASE REPORT: A 29-year-old woman undergoing a left hallux valgus repair received a continuous popliteal sciatic nerve block for postoperative analgesia. Postoperatively, 6 hours after the commencement of a ropivacaine 0.2% infusion, she reported feelings of tingling, clenching pain, and missing-limb sensation below the ankle. The surgical site remained painless. Sensation elicited by touch and propioception were normally perceived. Only sensations for pinprick and heat were impaired. The ropivacaine infusion was stopped, followed 2.5 hours later by the complete regression of any abnormal sensation. Meanwhile, pain at the surgical site was scored at 50 mm on a 100-mm visual analogic scale. As the infusion of ropivacaine was resumed, the abnormal sensations reappeared. The catheter was removed, and abnormal sensations again disappeared. The patient was discharged from hospital without further complications. CONCLUSIONS: This observation suggests that phantom-limb pain can be of late-onset and might occur during a continuous infusion of low-concentration local anesthetic responsible only for an analgesic block, as shown by the fact that only thermal and pinprick sensations, known to depend on Adelta-fibers and C-fibers, were altered. Therefore, this case contradicts the usual belief that a profound block is necessary to elicit phantom-limb pain.

Adult↗