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Biomedical subjects

P Coriat

Publications and source records attributed to P Coriat.

At least 37 records · Page 2Linked to original sources

Fluoride ion toxicity in rabbit kidney thick ascending limb cells.

BACKGROUND AND OBJECTIVE: Some halogenated agents, especially methoxyflurane, because of a higher level of fluoride production, induce a renal concentrating defect that could be related to an ascending limb impairment. We investigated the mechanisms of fluoride toxicity on an immortalized cell line. METHODS: Cells were cultured for 2, 6 or 24 h in the presence of fluoride. Toxicity evaluation was based on: cell numbers, protein content, leucine-incorporation, lactate dehydrogenase (LDH) and N-acetyl-beta-glucosaminidase (NAG) releases, Na-K-ATPase and Na-K-2Cl activities, electron microscope studies. Infrared analysis and fluoride microdetermination allowed crystal components. RESULTS: At 5 mmol after 24 h, fluoride decreased cell numbers (-14%, *P < 0.05), protein content (-16%*), leucine incorporation (-54%*), Na-K-2Cl activity (-84%*), increased LDH (+145%*) and NAG release (+190%*). Na-K-ATPase was more sensitive and impaired from 1 mmol for 24h and after 2 h at 5 mmol. Crystal formation in mitochondria occurred after 6 h at 5 mmol. Infra-red analysis and fluoride microdetermination established that crystals contained sodium, phosphate and fluoride. CONCLUSIONS: The results suggest that the Na-K-ATPase pump is a major target for fluoride toxicity in Henle's loop.

Acetylglucosaminidase↗

Role of nitric oxide and cyclooxygenase pathways in the coronary vascular effects of halothane, isoflurane and desflurane in red blood cell-perfused isolated rabbit hearts.

BACKGROUND: The coronary vascular endothelium could mediate some of the coronary effects of halogenated anaesthetic agents. The role of the endothelial vasodilator substances nitric oxide (NO) and prostaglandins (PGs) in the coronary effects of halothane and isoflurane remains to be determined and has not been investigated for desflurane. In this study, the roles of NO and cyclooxygenase pathways in the coronary effects of halothane, isoflurane and desflurane were studied in isolated red blood cell-perfused rabbit hearts. METHODS: Rabbit hearts were perfused by a Langendorf technique with red blood cells mixed with modified Krebs-Henseleit buffer. Coronary blood flow (CBF), oxygen consumption and myocardial performance were evaluated during exposure to 0.5, 1 and 2 rabbit minimum alveolar concentrations of halothane, desflurane and isoflurane. Thereafter, the same protocol was applied with the addition of N(G)-nitro-L-arginine (L-NNA), indomethacin or a combination of both inhibitors. RESULTS: Similar and significant increases in CBF were observed with increasing concentrations of isoflurane and desflurane. In contrast, CBF did not change with halothane. The combination of the two antagonists abolished desflurane-induced vasodilation, whereas it did not change the isoflurane-mediated increase in CBF. Halothane-induced vasoconstriction was observed in the presence of a combination of indomethacin with L-NNA. CONCLUSIONS: Halothane and desflurane induce the release of vasodilating prostaglandins and NO in rabbit coronary arteries. In contrast, these mediators are not involved in the coronary vasodilating properties of isoflurane.

Anesthetics, Inhalation↗

Remifentanil compared with sufentanil during extra-corporeal shock wave lithotripsy with spontaneous ventilation: a double-blind, randomized study.

BACKGROUND: The pharmacokinetic properties of remifentanil may allow a rapid analgesic action during painful procedures and short lasting postoperative respiratory depression. METHODS: We carried out a randomized, blind, study in 60 patients to compare remifentanil (continuous i.v. infusion starting at 0.025 micro g kg(-1) min(-1)) and sufentanil (i.v. doses of 0.15 micro g kg(-1)) during extra-corporeal shock wave lithotripsy (ESWL). Pain was assessed using a numerical pain scale (0-100), and pain relief was defined as a score < or =30. Respiratory depression was defined as a ventilatory frequency less than10 breaths min(-1) on two occasions or a peripheral oxygen saturation < or =92%, or administration of naloxone. RESULTS: The quality of analgesia was similar in both groups, during and after ESWL. During ESWL, there was no significant difference in respiratory depression in the remifentanil and sufentanil groups (53 vs 73%, NS). The percentage of satisfied patients (73 vs 83%, NS) and satisfied surgeons (97 vs 100%, NS) did not significantly differ between groups. After the procedure patients given remifentanil had less respiratory depression (20 vs 53%, P<0.05) and less nausea and vomiting (3 vs 20%, P<0.05). CONCLUSION: A continuous i.v. infusion of remifentanil provided comparable analgesia and caused less respiratory depression and nausea and vomiting than i.v. boluses of sufentanil in patients undergoing extra-corporeal shock wave lithotripsy.

Adult↗

Is morphine-induced sedation synonymous with analgesia during intravenous morphine titration?

BACKGROUND: Postoperative morphine titration frequently induces sedation. The assumption is made that patients sleep when their pain is relieved. Some patients complain of persistent pain when they awake. We studied the time-course of sedation and analgesia to understand the determinants of patients' sleep during morphine titration. METHODS: Seventy-three patients requiring morphine titration in a post-anaesthetic care unit after major surgery, were studied. Fifty-two patients slept (Sleep group) and 21 did not (Awake group). When a patient slept during titration, morphine was discontinued. Visual analogue pain scale (VAS), Ramsay score (RS), and the bispectral index (BIS) were recorded at the beginning of titration (STonset), at sleep onset (STsleep), then 5, 10, 20, and 30 min afterwards (ST4). RESULTS: In the Sleep group, mean (SD) RS increased from 1.7 (0.4) to 2.4 (0.6) (P<0.05 vs STonset) and BIS decreased from 95 (5.0) to 89.8 (10.2) between STonset and STsleep (P<0.05), RS remained stable thereafter. Conversely, RS and BIS remained unaltered in the Awake group. The reduction in VAS was comparable between groups (from 78 (17) to 39 (21), and from 64 (16) to 30.4 (11), respectively). Even though mean (SD) VAS was 39 (21) at ST4 in the Sleep group, 13 patients (25%) maintained a VAS above 50 mm. CONCLUSION: We observed dissociated effects of morphine on the time-course of sedation and analgesia with sedation occurring first, followed by analgesia. Therefore, morphine-induced sedation should not be considered as an indicator of an appropriate correct level of analgesia during i.v. morphine titration.

Adult↗

Effects of halothane and isoflurane on the contraction, relaxation and energetics of rat diaphragmatic muscle.

BACKGROUND: The inotropic effects of halogenated anaesthetics on diaphragmatic muscle remain a matter of debate. Their effects on its relaxation are poorly understood, although diaphragmatic relaxation is recognized as an important physiological process that may interfere with diaphragmatic performance, fatigue and arterial blood flow. METHODS: The effects of halothane and isoflurane (1 or 2 x minimum alveolar concentration [1 or 2 MAC]) on contraction and relaxation of rat diaphragm muscle strips (n = 40) were studied in vitro from force-velocity curves obtained at various loads from isotonic to isometric conditions. From these curves we determined the peak power output and the curvature. Data are mean (SD) percentage of baseline values. RESULTS: At I MAC, isoflurane and halothane induced no significant inotropic and lusitropic effects. At 2 MAC, isoflurane induced a negative inotropic effect (active force, 93(5)% of baseline). Halothane and isoflurane induced a significant decrease in the peak power output at 2 MAC (88(8) and 86(9)% of baseline; P < 0.05), without significant changes in the curvature of the force-velocity curve. At 2 MAC isoflurane under high loads and halothane under low loads induced moderate negative lusitropic effects. CONCLUSION: Halothane and isoflurane induced very moderate inotropic and lusitropic effects, suggesting that the decrease in diaphragm function observed in vivo is not related to a direct effect on diaphragmatic contractility.

Anesthetics, Inhalation↗

Initial imaging assessment of severe blunt trauma.

OBJECTIVES: Total body computed tomography (CT) scan is increasingly used in traumatised patients, but the need for an initial rapid imaging assessment beforehand remains unknown. To address this problem, we assessed the value of an initial imaging assessment (chest X-ray, pelvic X-ray, abdominal ultrasonography) in severely traumatised patients in a prospective study. DESIGN AND SETTING: Prospective study of a cohort in a level 1 trauma centre of an university teaching hospital. PATIENTS AND INTERVENTIONS: 400 patients with severe blunt trauma. Within 30 min of arrival in the hospital, these patients underwent a rapid imaging assessment at the bedside, including chest and pelvic X-ray, and an abdominal ultrasonography. The decision taken for each imaging technique (chest drainage or thoracotomy, pelvic angiography, and laparotomy, respectively) was judged as appropriate or inappropriate. MEASUREMENTS AND RESULTS: Emergency chest drainage or thoracotomy was performed in 78 cases (78 appropriate), pelvic angiography in 8 cases (5 appropriate) and immediate laparotomy in 48 cases (47 appropriate). Emergency treatment was decided in 108 patients, and the decisions were considered appropriate in 392 (98%, 95% CI: 97%-99%) cases. Three variables (heart rate, systolic arterial pressure and Glasgow Coma Scale) were independent predictors of the need for an emergency decision, but among patients who had none of these criteria, 16% required an emergency decision. CONCLUSIONS: A simple and rapid initial imaging assessment enabled appropriate emergency decisions before further imaging assessment was performed. We recommend that every patient with severe blunt trauma receive this initial assessment.

Abdominal Injuries↗

[Anesthesia in coronary disease].

Patients undergoing non-cardiac surgery and who have coronary artery disease run a high risk of myocardial infarct. Diagnosis and postoperative management is presently based on assessment of cardiac troponin I. Associated with optimal postoperatory management, several approaches can limit the occurrence of postoperatory coronary complications and improve the life expectancy of surgical patients with high cardiovascular risk. They include the possibility of preoperatory myocardial revascularisation and the prophylactic, postoperatory administration of cardiovascular medications (non-steroidal anti-inflammatory drugs, beta-blockers and alpha 2 receptor agonists).

Adrenergic beta-Antagonists↗

Validation of a software designed for computed tomographic (CT) measurement of lung water.

OBJECTIVE: The in-vitro validation of a computed tomographic (CT) software specifically designed for quantifying the volume of water contained in the lung. DESIGN: An in-vitro, ex-vivo study. In 1993, a postmortem left pneumonectomy was performed in a patient who died from acute respiratory distress syndrome. The lung was fixed, inflated and dried according to a technique proposed by Markarian and Dailey in 1975 aimed at producing a lung specimen spongy in texture and suitable for radiography. MEASUREMENTS AND RESULTS: In 1999, 13 CT scans of this lung specimen were performed corresponding to different bronchial instillations of known volumes of water and albumin 4%. The different lung weights resulting from the successive bronchial instillations were calculated using a specially designed software, Lungview, adapted for CT measurements and compared with the actual lung weight measured by an electronic scale. The increase in lung weight measured by Lungview was closely correlated with the actual increase in lung weight resulting from bronchial instillation of water and albumin (y = 0.99x - 23, r = 1 for water and y = x - 17, r = 1 for albumin 4%) and the precision of the bias was 7 g for water and 3 g for albumin 4%. CONCLUSIONS: This study shows that the CT software Lungview accurately measured the volume of lung water present within an air-dried exsanguine human lung.

Aged↗

Assessment of PEEP-induced reopening of collapsed lung regions in acute lung injury: are one or three CT sections representative of the entire lung?

OBJECTIVES: To study whether PEEP-induced reopening of collapsed lung regions--defined as the decrease in nonaerated lung volume measured on a single or three computerized tomographic (CT) sections--is representative of the decrease in overall nonaerated lung volume. DESIGN: Review of 39 CT scans obtained in consecutive patients with Acute Lung Injury. SETTINGS: Fourteen-bed surgical intensive care unit of a University Hospital. MEASUREMENTS AND RESULTS: PEEP-induced decrease in nonaerated lung volume was measured in 39 patients with ALI on a single juxtadiaphragmatic CT section, on three CT sections--apical, hilar, and juxtadiaphragmatic--and on contiguous apex-to-diaphragm CT sections. The percentage of decrease in nonaerated lung volume following PEEP, was compared between one, three and all CT sections using a linear regression analysis and Bland and Altman's method. The decrease in nonaerated lung volume measured on a single and three CT sections was significantly correlated with the decrease in nonaerated lung volume measured on all CT sections: R=0.83, P<0.0001 for one CT section and R=0.92, P<0.0001 for three CT sections. However, measurements performed on a single CT section were poorly representative of the overall lung: bias -6%, limits of agreement ranging between -37% and +25%. Measurements performed on three CT sections overestimated by 11% the overall decrease in nonaerated lung volume: bias -11%, limits of agreement ranging between -29% and +7%. CONCLUSIONS: PEEP-induced reopening of collapsed lung regions measured on a single or three CT sections sensibly differs from the reopening of collapsed lung regions measured on the overall lung. The inhomogeneous distribution of PEEP-induced reopening of collapsed lung regions along the cephalocaudal axis probably explains these discrepancies.

Adult↗

Postoperative titration of intravenous morphine.

BACKGROUND AND OBJECTIVE: Intravenous morphine titration is used to obtain postoperative pain relief, but few studies have assessed the appropriate regimen. In a quality programme, we performed a prospective non-randomized study of morphine titration in a postanaesthesia care unit (PACU). METHODS: Four regimens of morphine titration were studied: every 10 (group 1, n = 400) or 5 min (group 2, n = 400) with a maximum of five intravenous boluses; every 5 min, without any limitation in the number of boluses (groups 3 and 4, n = 400 each); in groups 1, 2, and 3, subcutaneous morphine was administered 4 h after titration. In group 4, administration of subcutaneous morphine was allowed only 2 h after titration. A visual analogue pain scale (VAPS) > 30 mm was required to administer morphine and pain relief was defined as a VAPS < or = 30 mm. RESULTS: After morphine titration, VAPS was lower and the number of patients with pain relief was greater in patients from groups 3 and 4. Patients from group 4 had the lowest VAPS (26 +/- 17 mm) and the highest percentage of pain relief (73%) at the end of the PACU period. The number of sedated patients increased in groups 3 (62%) and 4 (61%) compared with group 1 (27%). No significant differences in morphine-related adverse effects were observed. CONCLUSION: Intravenous morphine titration every 5 min with an unlimited number of boluses and early subcutaneous administration provided the best analgesic regimen.

Adult↗

Endovascular treatment of abdominal aortic aneurysms: is there a benefit regarding postoperative outcome?

BACKGROUND AND OBJECTIVE: The endovascular treatment of abdominal aortic aneurysms has raised great interest amongst vascular surgeons. The aim of this study was to compare the postoperative morbidity and mortality rates of endovascular treatment with those of open surgery, from the anaesthesiologist's standpoint. METHODS: From January 1997 to June 2000, 425 consecutive patients with abdominal aortic aneurysms were referred for regular surgery. Thirty-nine patients who needed a visceral or renal artery revascularization, or a nephrectomy were excluded. The remaining 386 patients were studied in a prospective manner. Aneurysms were evaluated with spiral computerized tomography scanning and calibrated aortography. After informed consent, only those patients with a suitable vascular anatomy underwent endovascular treatment (n = 193). All other patients underwent open surgery and are considered as a control group (n = 193). Endovascular treatment was performed by a femoral or an iliac retroperitoneal route. All stent-grafts were made to measure using auto-expandable stainless-steel stents covered with a standard polyester prosthetic graft. RESULTS: Six patients in the endovascular treatment group needed to be converted to the open surgical technique (during the same operation) because of rupture of the iliac bifurcation (1 patient), a large endoleak (2 patients), or technical problems (3 patients). CONCLUSION: The amount of bleeding and the need for blood products were significantly lower in the endovascular treatment group. Despite the absence of significant differences regarding cardiac complications and mortality, there was a lesser incidence of pneumonia, acute respiratory and renal failure. Patients in the endovascular treatment group spent less time in the intensive care unit and in the Hospital.

Age Factors↗

S-100beta protein levels do not correlate with stroke in patients undergoing carotid endarterectomy under general anesthesia.

OBJECTIVE: To establish the S-100beta protein profile during carotid artery surgery to show a possible correlation between postoperative stroke and this biochemical marker. DESIGN: Prospective, nonrandomized study. SETTING: Departments of anesthesiology, biochemistry, and vascular surgery in a single university hospital. PARTICIPANTS: One hundred patients consecutively scheduled for carotid endarterectomy. MEASUREMENTS AND MAIN RESULTS: Postoperative neurologic complications were defined as major, occurrence of a postoperative permanent stroke, or minor, occurrence of a new postoperative transient ischemic attack lasting < 2 hours. Serum samples were obtained before induction, before carotid artery cross-clamping, after declamping, at the end of surgery, during recovery, and on the first postoperative day. Concentrations of S-100beta were analyzed using a commercially available kit (LIA-mat S300 analyzer, Byk-Sangtec Medical, Bromma, Sweden). Ninety-five patients awoke without a neurologic defect. Three patients experienced a permanent stroke, and 2 patients had a transient ischemic attack. S-100 basal values were unrelated to preoperative status, including hypertension, neurologic status, renal function, and degree of the carotid lesion. S-100 concentration increased slightly but significantly at the end of surgery and remained stable until the first postoperative day. S-100 profile during the procedure was independent of the duration of carotid artery cross-clamping and the need for a shunt. S-100 serum level was not significantly different in the patients with a postoperative ischemic event in comparison with the entire group. The S-100 profile was not increased in 2 of 3 patients with a permanent stroke and in 1 of 2 patients with a transient ischemic attack in comparison with the 95 patients with uneventful recovery. CONCLUSION: S-100 concentration slightly increased at the end of surgery and remained high until the first postoperative day in all patients. S-100 was not significantly different in the patients with postoperative stroke. S-100 did not serve as a marker for postoperative stroke after carotid artery surgery. This fact must be taken into account during further investigations of S-100.

Aged↗

Should the angiotensin II antagonists be discontinued before surgery?

UNLABELLED: Angiotensin II antagonists (AIIA) are part of a new rational treatment of hypertension. Because adverse circulatory effects during anesthesia can occur in patients chronically treated with angiotensin-converting enzyme inhibitors, some clinicians discontinue them at least 24 h before operation. No data are available concerning AIIA administration in patients scheduled for vascular surgery performed under general anesthesia. The aim of this prospective randomized study was to compare hemodynamics during induction of anesthesia in patients chronically treated with AIIA and those of patients not receiving this drug on the morning before operation. Thirty-seven patients chronically treated with AIIA for hypertension were randomly assigned to two groups: Group I: AIIA discontinued on the day before surgery (n = 18); Group II: AIIA given 1 h before anesthesia (n = 19). Patients received sufentanil 0.4 microg/kg, propofol 1.5 mg/kg, and atracurium 0.5 mg/kg. During the procedure, the anesthesiologist was required to maintain systolic blood pressure and heart rate within 30% of baseline values using intravascular fluid administration and vasoconstric- tors (e.g. , ephedrine, phenylephrine, or terlipressin). Hemodynamic variables were recorded each 1 min. Hemodynamic study ended at incision. The number and duration of hemodynamic events were collected, and total doses of vasoactive drugs were noted in each group. Systolic arterial pressure was significantly decreased in Group II at 5, 15 and 23 min after induction of anesthesia (*P < 0.05). In this group, the decrease in systolic arterial pressure was associated with more frequent episodes of hypotension (AIIA withdrawn: 1 +/- 1; AIIA given: 2 +/- 1; P < 0.01), with a larger number of patients developing at least 1 episode of hypotension (AIIA withdrawn: 12; AIIA given: 19; P < 0.01), and a longer duration of an episode of hypotension (AIIA withdrawn: 3 +/- 4 min; AIIA given: 8 +/- 7 min; P < 0.01), and an increased need for vasoactive drugs. In conclusion, blockade of the renin-angiotensin system increases the potential hypotensive effect of anesthetic induction. A severe hypotensive episode, requiring vasoconstrictor treatment, occurs after induction of general anesthesia in patients chronically treated with AIIA. Recommendations to discontinue AIIA drugs on the day before the surgery may be justified. IMPLICATIONS: This prospective randomized study demonstrated that more severe hypotensive episodes, requiring vasoconstrictor treatment, occur after induction of general anesthesia in patients chronically treated with AIIA and receiving this drug on the morning before operation, in comparison with those in whom AIIA were discontinued on the day before operation. Recommendations to discontinue these drugs on the day before the surgery may be justified.

Aged↗

Extracellular calcium modulates the effects of protamine on rat myocardium.

UNLABELLED: We studied the effects of protamine (10-300 microg. mL(-1)) as well as its interaction with heparin in rat left ventricular papillary muscles in vitro at calcium concentrations of 0.5 and 1 mM under low (isotony) and high (isometry) loads. Protamine induced a negative inotropic effect that was less pronounced at calcium 0.5 mM (active force at protamine 300 microg/mL, 84 +/- 20 vs 57 +/- 15% of baseline, P: < 0.05); whereas at calcium 1 mM there was a marked contracture of the muscle. For the smallest concentrations of protamine and at calcium 0.5 mM, we observed a moderate positive inotropic effect that was suppressed by nifedipine. Protamine induced a negative lusitropic effect under low load and decreased postrest potentiation, suggesting an impairment in the functions of the sarcoplasmic reticulum. Heparin was able to inhibit and reverse the negative inotropic effect of protamine. The negative inotropic effect of protamine is enhanced by an increase in extracellular calcium concentration. This negative inotropic effect is probably related to calcium overload and impairment in sarcoplasmic reticulum functions, and heparin can block these effects. IMPLICATIONS: The negative inotropic effect of protamine is enhanced by an increase in extracellular calcium concentration. This negative inotropic effect is probably related to calcium overload and impairment in sarcoplasmic reticulum functions, and heparin can block these effects.

Animals↗

Voluven, a lower substituted novel hydroxyethyl starch (HES 130/0.4), causes fewer effects on coagulation in major orthopedic surgery than HES 200/0.5.

UNLABELLED: Hydroxyethyl starch (HES) solutions are effective plasma volume expanders. Impairment of coagulation occurs with large HES volumes infused perioperatively. Therefore, a lower substituted novel HES (Voluven; Fresenius Kabi, Bad Homburg, Germany) was developed to minimize hemostatic interactions, and was compared with HAES-steril (Fresenius Kabi) (pentastarch) regarding safety and efficacy. We performed a prospective, randomized, double-blinded study in 100 major orthopedic surgery patients. Because the 95% confidence interval (-330 mL; +284 mL) for the treatment contrast Voluven-HAES-steril was entirely included in the predefined equivalence range (+/- 500 mL), comparable efficacy was established. Voluven interfered significantly less than HAES-steril with coagulation factor VIII levels and partial thromboplastin time postoperatively. Total amounts of red blood cells transfused were comparable between the Voluven and HAES-steril groups, but a significantly reduced need for homologous red blood cells was observed in the Voluven group. We conclude that in large-blood-loss surgery, Voluven has a comparable efficacy with HAES-steril and may reduce coagulation impairment, possibly leading to a smaller number of allogeneic blood transfusions. IMPLICATIONS: Hydroxyethyl starches are common plasma volume expanders, but may interfere with coagulation at large doses. We tested a novel hydroxyethyl starch specification (Voluven; Fresenius Kabi, Bad Homburg, Germany) which was developed to reduce hemostatic interactions while preserving its efficacy in restoring plasma volume in comparison to HAES-steril (pentastarch; Fresenius Kabi) in major orthopedic surgery.

Adolescent↗

Hemostatic changes in patients receiving hydroxyethyl starch: the influence of ABO blood group.

Hydroxyethyl starches (HES) interfere with coagulation because of their molecular structure and the amount infused during surgery. Coagulation defects include platelet dysfunction and a decrease of the VIII/von Willebrand factor complex (VIII/vWF). We examined the effects of 6% HES 200/0.6 on hemostasis by using an in vitro platelet function analyzer, the usual coagulation tests, the VIII/vWF complex assessment, and TEG analysis in patients undergoing abdominal surgery. The influence of the blood group was investigated. HES infusion induced primary hemostasis alterations, assessed by a prolonged platelet function analyzer closure time in the presence of epinephrine and adenosine diphosphate, which was not correlated with the platelet count. The decrease in VIII/vWF complex was proportional to the volume of infused HES (20 and 30 mL/kg) and was more pronounced in patients of the O blood group. The preoperative hypercoagulability status assessed by TEG analysis was reversed 24 h after HES infusion. In conclusion, 6% HES 200/0.6 induced immediate hemostasis alterations. Patients of the O blood group were likely to develop a von Willebrand-like syndrome after HES infusion. We conclude that intraoperative use of 6% HES 200/0.6 should be restricted in patients of the O blood group undergoing surgical procedures with high risk for bleeding.

ABO Blood-Group System↗