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Bruno Riou

Publications and source records attributed to Bruno Riou.

69 records · Page 4Linked to original sources
PubMed2003

Postoperative morphine consumption in the elderly patient.

BACKGROUND: It has been suggested that the dose of intravenous morphine used during postoperative titration is not modified by aging. The authors therefore studied morphine requirements in patients undergoing total hip replacement. METHODS: Intravenous morphine titration was administered as boluses, then subcutaneous morphine was administered every 4 h over 24 h. Pain was assessed by use of the visual analog scale (0 to 100), and the threshold required to administer morphine was 30. Young and elderly (> or =70 yr old) patients were compared. Data are mean +/- SD or odds ratio (OR) [95% CI]. RESULTS: Two hundred twenty-four patients (68%) were young and 105 (32%) were elderly. The initial visual analog scale was not significantly different between groups. The dose of intravenous morphine in the postanesthesia care unit was not significantly different between young and elderly patients (0.15 +/- 0.11 vs. 0.14 +/- 0.10 mg/kg, P = NS), in contrast to the dose of subcutaneous morphine (0.18 +/- 0.18 vs. 0.11 +/- 0.11 mg/kg, P < 0.001) in the ward. Only severe pain (visual analog scale of 70 or greater; OR, 10.5 [4.5-24.8]) was significantly associated with a high dose (greater than 0.15 mg/kg) of intravenous morphine, whereas severe pain (OR, 2.5 [1.6-4.0]), age less than 60 yr (OR, 2.3 [1.4-3.8]), and absence of a nonsteroidal antiinflammatory drug (OR, 1.9 [1.2-3.1]) were significantly associated with a high dose (greater than 0.12 mg/kg) of subcutaneous morphine. CONCLUSIONS: The dose of intravenous morphine during titration is not modified in elderly patients, in contrast to the dose administered subcutaneously over a prolonged period.

Aged↗
PubMed2003

Short- and long-term prognostic value of postoperative cardiac troponin I concentration in patients undergoing coronary artery bypass grafting.

BACKGROUND: The value of postoperative cardiac troponin I (cTnI) has been shown to indicate a higher risk of in-hospital death after cardiac surgery. The authors therefore assessed the long-term prognostic value of cTnI in patients undergoing elective coronary artery bypass grafting. METHODS: Consecutive patients (n = 202) were included and divided into two groups according to the postoperative value of cTnI (< or >/= 13 ng/ml). In-hospital mortality and nonfatal cardiac events (delayed extubation > 24 h; postoperative requirement of inotropic agent; ventricular and supraventricular arrhythmia; postoperative myocardial infarction) were recorded. Survivors were then followed up over a 2-yr period. Data are median and odds ratio (95% confidence interval). RESULTS: Of all patients, 174 (86%) had a low cTnI (4.1 ng/ml; range, 1.1-12.6) and 28 (14%) had a high cTnI (23.8 ng/ml; range, 13.4-174.6). In-hospital mortality was not significantly different (4 vs. 2%), whereas long-term mortality (18 vs. 3%, P = 0.006) and mortality from cardiac cause (18 vs. 1%, P < 0.001) was greater in patients with a high cTnI. A high cTnI was a significant factor predicting death (odds ratio, 7.3 [2.0-27.1]) or death from cardiac causes (odds ratio, 37.4 [4.2-334.4]). Nonfatal cardiac events were also more frequent in the hospital (64 vs. 41%, P = 0.02) and within the 2-yr follow-up period (39% vs. 16%, P = 0.03) in patients with high cTnI. CONCLUSION: A high postoperative peak of cTnI is associated with increased risk of death, death from cardiac causes, and nonfatal cardiac events within 2 yr after coronary artery bypass grafting.

Aged↗
PubMed2003

A comparison of intrathecal opioid and intravenous analgesia for the incidence of cardiovascular, respiratory, and renal complications after abdominal aortic surgery.

UNLABELLED: Major surgery evokes a stress response that can produce deleterious consequences, especially in a population at high risk for those complications. We tested the hypothesis that decreasing or eliminating one of the sources of stress by providing intense analgesia in the immediate postoperative period via application of neuraxial opioids would decrease major nonsurgical complications. Two-hundred-seventeen patients scheduled to undergo abdominal aortic surgery were randomly allocated to receive either general anesthesia alone (control) or general anesthesia combined with intrathecal opioid (1 micro g/kg sufentanil with 8 micro g/kg preservative-free morphine injected at the L4-5 interspace). Postoperative care was identical in the two groups, including patient-controlled analgesia. Each patient provided an assessment of postoperative pain using a visual analog scale. Postopera-tive complications were recorded according to criteria established a priori. The administration of intrathecal opioid provided more intense analgesia than patient-controlled analgesia during the first 24 h postoperatively (P < 0.05). There was no difference between groups for the incidence of combined major cardiovascular, respiratory, and renal complications (P > 0.05) or mortality (P > 0.05). The incidence of myocardial damage or infarction, as defined by abnormal plasma concentration of troponin I, did not differ between the two groups (P > 0.05). In patients undergoing major abdominal vascular surgery, decrease of one contributor to postoperative stress, by provision of intense analgesia for the intraoperative and initial postoperative period, via application of neuraxial opioid, does not alter the combined major cardiovascular, respiratory, and renal complication rate. IMPLICATIONS: Provision of intense analgesia for the initial postoperative period after major abdominal vascular surgery, via the administration of neuraxial opioid, does not alter the combined incidence of major cardiovascular, respiratory, and renal complications.

Aged↗
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

Aortic vasoreactivity during prolonged hypoxia and hypoxia-reoxygenation in senescent rats.

To determine the effects of prolonged hypoxia and hypoxia-reoxygenation in senescent blood vessels, isolated aortic rings from 4- and 24-month-old (mo) Wistar rats were submitted to prolonged hypoxia (50 min) or hypoxia/reoxygenation (20 min/30 min) and contractile function recorded. Phenylephrine-induced contraction and sodium nitroprusside- and acetylcholine-induced relaxations were measured after hypoxia or after hypoxia/reoxygenation. In 24 mo group, prolonged hypoxia increased (+83%, P<0.01) and prolonged initial hypoxic contraction, while hypoxic relaxation and delayed contraction were unchanged. Relaxation to acetylcholine was more reduced than in 4 mo group while contraction to phenylephrine and relaxation to sodium nitroprusside were similarly impaired. During reoxygenation, contraction was of same amplitude at both ages and the relaxation to acetylcholine was impaired but to a similar extent in both groups. In conclusion, hypoxic stress induces a greater endothelium-injury in senescent aorta, and increased transient hypoxic contraction, without aggravation of late hypoxic contraction. Aging does not exacerbate the impairment of aortic vasoreactivity after hypoxia-reoxygenation, especially endothelium-dependent relaxation, in sharp contrast to prolonged hypoxia. These age-related changes in vascular sensitivity to oxygen deprivation are different from those observed in coronary arteries, indicating that vasoreactivity during such pathological stress strongly depends on the type of vessel, especially during aging.

Acetylcholine↗
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

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

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

Brain death assessment using instant spectral analysis of heart rate variability.

OBJECTIVE: Confirmation of brain death requires an urgent diagnosis to allow rapid vital organ removal for transplantation. Evaluation of forebrain functions is commonly performed through electroencephalogram. Nevertheless, there are, for the moment, no methods that allow for an instantaneous evaluation of brainstem functions. During acute brain injury, heart rate variability is an independent neurologic prognosis indicator resulting from a close relationship between brain stem and cardiac autonomic nervous system. This study aims to evaluate a new heart rate variability spectral analysis method, on a beat-to-beat basis, continuously over the time, during brain death. DESIGN: Prospective, nonrandomized, observational study. SETTING: Intensive care unit. SUBJECTS: Ten patients (age range 25-64 yrs, mean age 41 yrs) with acute brain injury leading to brain death. INTERVENTION: No intervention beyond standard of care MEASUREMENTS AND MAIN RESULTS: Heart rate, arterial blood pressure, heart rate variability in time and frequency domains method, which included calculation of the instant center frequency of spectrum. Brain death was associated with tachycardia (R-R interval 703 +/- 69 vs. 551 +/- 34 msec, p <.05), dramatic reduction of the global spectral power (44.919 +/- 31.511 vs. 3.204 +/- 1.469 msec(2), p <.05), and an abrupt shift of instant center frequency to a higher frequency range (0.17 +/- 0.01 vs. 0.26 +/- 0.03 Hz, p <.05). CONCLUSIONS: Such a method allows an instant, noninvasive determination of brainstem death based on a time and frequency domain analysis of heart rate variability.

Adult↗
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↗