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Biomedical subjects

Benoit Vallet

Publications and source records attributed to Benoit Vallet.

8 recordsLinked to original sources
PubMed2003

Multicenter randomized comparison of the efficacy and safety of xenon and isoflurane in patients undergoing elective surgery.

BACKGROUND: All general anesthetics used are known to have a negative inotropic side effect. Since xenon does not have a negative inotropic effect, it could be an interesting future general anesthetic. The aim of this clinical multicenter trial was to test the hypothesis of whether recovery after xenon anesthesia is faster compared with an accepted, standardized anesthetic regimen and that it is as effective and safe. METHOD: A total of 224 patients in six centers were included in the protocol. They were randomly assigned to receive either xenon (60 +/- 5%) in oxygen or isoflurane (end-tidal concentration, 0.5%) combined with nitrous oxide (60 +/- 5%). Sufentanil (10 mcirog) was intravenously injected if indicated by defined criteria. Hemodynamic, respiratory, and recovery parameters, the amount of sufentanil, and side effects were assessed. RESULTS: The recovery parameters demonstrated a statistically significant faster recovery from xenon anesthesia when compared with isoflurane-nitrous oxide. The additional amount of sufentanil did not differ between both anesthesia regimens. Hemodynamics and respiratory parameters remained stable throughout administration of both anesthesia regimens, with advantages for the xenon group. Side effects occurred to the same extent with xenon in oxygen and isoflurane-nitrous oxide. CONCLUSION: This first randomized controlled multicenter trial on the use of xenon as an inhalational anesthetic confirms, in a large group of patients, that xenon in oxygen provides effective and safe anesthesia, with the advantage of a more rapid recovery when compared with anesthesia using isoflurane-nitrous oxide.

Adjuvants, Anesthesia↗
PubMed2003

Gastric capnometry with air-automated tonometry predicts outcome in critically ill patients.

CONTEXT: Contrary to tonometer gastric intramucosal pH, there is currently no validated threshold prognostic value for Pco2 gap (tonometer gastric mucosal Pco2 minus arterial Pco2) in the critically ill patient. OBJECTIVE: To demonstrate a relationship between Pco2 gap and mortality in mechanically ventilated patients. DESIGN AND SETTING: Inception cohort study from a 9-month prospective survey of 95 consecutively ventilated critically ill patients in a teaching hospital. PATIENTS: All the ventilated patients of the intensive care unit were included at their admission. MEASUREMENTS AND MAIN RESULTS: Gastric Pco2 using regional capnometry with air-automated tonometry, arterial gas, lactate, and organ system failure score were measured at admission and after 6, 12, 24, 48, 72, 96, and 120 hrs. For the entire population, the 28-day mortality was 44%. In multivariate analysis, independent predictors of death were organ system failure score (odds ratio, 2.12; 95% confidence interval, 1.02-3.14), 24-hr Pco2 gap (odds ratio, 1.57; 95% confidence interval, 1.10-2.24), and 24-hr lactate (odds ratio, 1.48; 95% confidence interval, 1.06-2.05). We found a threshold value of 20 mm Hg for Pco2 gap and 2.5 mmol/L for lactate, which was associated with a sensitivity of 0.70 and 0.72, respectively, and a specificity of 0.72 and 0.73, respectively. CONCLUSION: The Pco2 gap is a marker of mortality in ventilated patients in the intensive care unit.

Adult↗
PubMed2002

Dobutamine and gastric-to-arterial carbon dioxide gap in severe sepsis without shock.

OBJECTIVES: To evaluate the effect of an early dobutamine infusion on gastrointestinal perfusion in patients with severe sepsis. DESIGN: Prospective, randomized, controlled, multicenter clinical study. SETTING: Six medical and/or surgical intensive care units (ICU) of teaching hospitals. PATIENTS: Forty-two patients with severe sepsis. INTERVENTIONS: Patients were divided into two groups according to gastric-to-arterial CO2 gap (DeltaCO2) [normal DeltaCO2 group ( n=17): DeltaCO2 < or = 8 mmHg; increased DeltaCO2 group ( n=25): DeltaCO2 > 8 mmHg]. Patients within each group were then randomized to receive either dobutamine (5 microg/kg per min) or saline for 72 h. MEASUREMENTS AND MAIN RESULTS: SAPS II was similar in both groups [group 1: 44.0 (33.0-56.5); group 2: 48.5 (40.5-59.0), p=0.27]. At ICU admission, mean arterial pressure was lower in the high DeltaCO2 group [73.0 (67.0-79.5) mmHg, p=0.03] than in the normal DeltaCO2 group [84.0 (73.7-104.0) mmHg] while blood lactate [normal DeltaCO2 group: 1.6 (0.8-2.3); high DeltaCO2 group: 1.6 (1.1-1.9) mmol/l] was similar for the two groups. DeltaCO2 was significantly lower in the normal DeltaCO2 group [5.0 (2.0-6.0) mmHg)] than in the high DeltaCO2 group [11.0 (10.0-19.0) mmHg]. Dobutamine infusion did not significantly change hemodynamics, blood lactate concentration or tonometric parameters in any group within the first 72 h and had no particular beneficial effect in this population. CONCLUSIONS: An early infusion of dobutamine at a fixed dose of 5 microg/kg per min during the first 72 h of severe sepsis does not influence gastric DeltaCO2.

APACHE↗
PubMed2002

Small intestine intramucosal PCO(2) and microvascular blood flow during hypoxic and ischemic hypoxia.

OBJECTIVE: To determine whether small intestine intramucosal PCO(2) and mucosal blood flow changes would be different between ischemic and hypoxic hypoxia. DESIGN: Randomized animal experiment. SETTING: Research laboratory. SUBJECTS: Anesthetized, mechanically ventilated, and surgically instrumented pigs. INTERVENTIONS: Systemic oxygen delivery was lowered in a stepwise manner to decrease it beyond critical oxygen delivery by lowering either FIO(2) or blood volume. MEASUREMENTS AND MAIN RESULTS: In hypoxic hypoxia pigs (n = 6), arterial oxygen concentration and oxygen delivery decreases were achieved by progressively reducing arterial PO(2) while cardiac index remained unchanged. In ischemic hypoxia pigs (n = 5), oxygen delivery reduction was achieved by progressively reducing cardiac index while arterial PO(2) remained unchanged. In control pigs, oxygen delivery remained unchanged. The lowest oxygen delivery measured in both hypoxia and ischemia experiments was 3.60 +/- 0.26 vs. 2.93 +/- 0.77 mL x kg(-1) x min(-1), respectively (p =.23). At the lowest oxygen delivery level, differences between ischemic hypoxia and hypoxic hypoxia experiments were observed for arterial lactate concentration (468 +/- 308 vs. 1070 +/- 218 mmol/L, respectively; p =.03), mixed venous arterial PCO(2) difference (10 +/- 7 vs. 4 +/- 2 torr, respectively; p =.04), and small intestine mucosal blood flow (6.2 +/- 2.1 vs. 15.7 +/- 7.4 perfusion units, respectively; p =.02). Small intestine intramucosal-arterial difference was higher in ischemic hypoxia than in hypoxic hypoxia (52 +/- 15 vs. 31 +/- 12 torr, respectively; p =.03). CONCLUSION: Small intestine intramucosal PCO(2) increases may indicate systemic oxygen uptake supply limitation in ischemic and hypoxic hypoxia related to conditions of mucosal flow stagnation and CO(2) generation.

Analysis of Variance↗
PubMed2002

Endothelial cell dysfunction and abnormal tissue perfusion.

OBJECTIVE: To determine the precise role of the myoendothelial regulatory unit in improved tissue perfusion and metabolic regulation. DATA SOURCES AND STUDY SELECTION: A review of the published literature (MEDLINE and other original articles and reviews) on endothelial cells, vascular reactivity, and tissue perfusion. DATA EXTRACTION AND SYNTHESIS: According to the concept of intrinsic metabolic regulation, vasodilation in tissues with relatively high metabolic rates competes with sympathetic vasoconstrictor tone, thereby adjusting the balance between local tissue oxygen supply and demand. Although the nature of the oxygen-sensitive structures acting at the local tissue level is not completely understood, endothelial cells in direct contact with blood have a number of properties that confer the potential to act as effective oxygen sensors. The endothelium and smooth muscle of arteries and arterioles seem to be coupled both structurally and functionally. Sensing involves local depolarization and hyperpolarization of the capillary endothelial cell, and communication is achieved by an electronic spread via endothelium-smooth muscle cell-to-cell gap junctions. Therefore, during hypoxic challenge, the ability of a tissue to extract oxygen-and to minimize shunting through areas with a high rate of perfusion relative to their oxygen uptake-may be considered an integrative test of endothelium function and microcirculatory coordination. CONCLUSION: Endothelial cells seem to play a central role in coordinating the microcirculatory system and promoting tissue perfusion and oxygen supply. In a pathologic situation such as sepsis, abnormal interendothelial cell coupling and an abnormal arteriolar conducted response may account for impaired tissue perfusion and abnormal oxygen extraction.

Animals↗