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Biomedical subjects

O Bastien

Publications and source records attributed to O Bastien.

At least 19 recordsLinked to original sources
PubMed2006

Respiratory variations in pulse oximeter waveform amplitude are influenced by venous return in mechanically ventilated patients under general anaesthesia.

BACKGROUND AND OBJECTIVES: Respiratory variations in pulse oximetry plethysmographic waveform amplitude (DeltaPOP) are related to respiratory variations in arterial pulse pressure (DeltaPP) in the critical care setting. The aims of this study were to test the hypothesis that in mechanically ventilated patients undergoing general anaesthesia, DeltaPOP calculation is feasible and can detect changes in preload. METHODS: Twenty-five mechanically ventilated patients were studied immediately after induction of general anaesthesia. Haemodynamic data (mean arterial pressure [MAP], central venous pressure [CVP], DeltaPP and DeltaPOP) were recorded at baseline, before and after tilting the patient from anti-Trendelenburg to Trendelenburg position in order to induce preload changes. RESULTS: Change from anti-Trendelenburg to Trendelenburg position induced changes in MAP (58 +/- 9 to 67 +/- 10 mmHg, P < 0.05), CVP (4 +/- 4 to 13 +/- 5 mmHg, P < 0.05), DeltaPP (14 +/- 8 to 7 +/- 5%, P < 0.05) and DeltaPOP (17 +/- 12 to 9 +/- 5%, P < 0.05). There was a significant relationship between DeltaPOP in anti-Trendelenburg position and percent change in MAP after volume expansion (r = 0.82; P < 0.05). CONCLUSIONS: DeltaPOP can be determined in the operating room and is influenced by changes in preload. This new index has potential clinical applications for the prediction of fluid responsiveness.

Adult↗
PubMed2006

[Impact of the guidelines on clinical practice of artificial nutrition in intensive care unit after cardiovascular and thoracic surgery].

OBJECTIVE: To analyze the impact of an artificial nutrition program in post-anaesthesia intensive care unit. STUDY DESIGN: Observational study. PATIENTS AND METHODS: Patients with length of stay greater than 8 days after cardiovascular and thoracic surgery: Group 1: 34 patients (4-month period in 2000); group 2: 15 patients (2-month period in 2001); group 3: 40 patients (4-month period in 2003). Between these 3 periods, informations of physicians and written protocol in order to improve their nutritional knowledge. After analysis of variance (P<0.05). Newman-Keuls tests to compare themselves each groups. RESULTS: Anthropometric, demographic and clinical parameters were similar in the 3 groups. Energic intakes were less than 80% of basal energetic expenditures in 33%, 33 and 22% of patient, respectively (NS). Caloric and nitrogen intakes were less than recommended, respectively 19+/-6 (mean+/-SD), 21+/-7 and 21+/-8 kcal/kg/24 h and 102+/-32, 111+/-31 and 92+/-40 mg/kg/24 h (NS). However enteral nutrition was administered in 49, 40 and 100% of patients respectively (P<0.001). The glucid/lipid ratio improved from 0.47 in group 1 up to 0.68 in group 3 (P<0.0001). Vitamins, oligoelements and clinical and biological monitoring of artificial nutrition improved (P<0.001). CONCLUSION: A clinical audit demonstrated an improvement in artificial nutrition parameters but no significant change in others.

Aged↗
PubMed2006

Metabolomic, proteomic and biophysical analyses of Arabidopsis thaliana cells exposed to a caesium stress. Influence of potassium supply.

The incorporation and localisation of 133Cs in a plant cellular model and the metabolic response induced were analysed as a function of external K concentration using a multidisciplinary approach. Sucrose-fed photosynthetic Arabidopsis thaliana suspension cells, grown in a K-containing or K-depleted medium, were submitted to a 1 mM Cs stress. Cell growth, strongly diminished in absence of K, was not influenced by Cs. In contrast, the chlorophyll content, affected by a Cs stress superposed to K depletion, did not vary under the sole K depletion. The uptake of Cs was monitored in vivo using 133Cs NMR spectroscopy while the final K and Cs concentrations were determined using atomic absorption spectrometry. Cs absorption rate and final concentration increased in a K-depleted external medium; in vivo NMR revealed that intracellular Cs was distributed in two kinds of compartment. Synchrotron X-ray fluorescence microscopy indicated that one could be the chloroplasts. In parallel, the cellular response to the Cs stress was analysed using proteomic and metabolic profiling. Proteins up- and down-regulated in response to Cs, in presence of K+ or not, were analysed by 2D gel electrophoresis and identified by mass spectrometry. No salient feature was detected excepting the overexpression of antioxidant enzymes, a common response of Arabidopsis cells stressed whether by Cs or by K-depletion. 13C and 31P NMR analysis of acid extracts showed that the metabolome impact of the Cs stress was also a function of the K nutrition. These analyses suggested that sugar metabolism and glycolytic fluxes were affected in a way depending upon the medium content in K+. Metabolic flux measurements using 13C labelling would be an elegant way to pursue on this line. Using our experimental system, a progressively stronger Cs stress might point out other specific responses elicited by Cs.

Arabidopsis↗
PubMed2005

Identification and characterization of two genes (MIP-1beta, VE-CADHERIN) implicated in acute rejection in human heart transplantation: use of murine models in tandem with cDNA arrays.

BACKGROUND: Genes and mechanisms of action involved in human acute rejection after allogeneic heart transplantation remain to be elucidated. The use of a murine allograft model in tandem with cDNA arrays and quantitative real-time polymerase chain reaction (Q-PCR) can greatly help in identifying key genes implicated in human heart acute rejection. METHODS AND RESULTS: Hearts from Balb/c mice were either not transplanted or transplanted heterotopically in the abdomen of Balb/c (isografts) and C57BL/6 (allografts) mice. Histological analysis showed acute rejection only in allografts. Total RNA was extracted from isografts (n=3), allografts (n=4), and not transplanted hearts (n=4); reverse transcribed; and labeled with P32. Each probe was hybridized to cDNA macroarrays. Eight genes were overexpressed and 7 genes were underexpressed in allografts compared with isografts. Macrophage inflammatory protein-1beta (MIP-1beta), an overexpressed gene, and VE-cadherin, an underexpressed gene, were validated by immunohistochemistry and Q-PCR in the murine models. Genes of interest, validated in the 3 murine groups, were then investigated in human heart tissues. Immunohistochemistry and Q-PCR performed on endomyocardial biopsies after heart transplantation showing no rejection (n=10) or grade IB (n=10) or IIIA (n=10) rejection, according to International Society of Heart and Lung Transplantation criteria, confirmed the results obtained from the murine model. CONCLUSIONS: We have demonstrated that the upregulation of MIP-1beta and downregulation of VE-cadherin may strongly participate in human acute heart rejection.

Animals↗
PubMed2004

[Predictors of in-hospital mortality in the surgical management of acute type A aortic dissections: impact of anticoagulant therapies].

OBJECTIVE: The purpose of this investigation was to study the incidence and consequences of anticoagulant therapy in the surgical management of acute aortic dissections. STUDY DESIGN: Retrospective study. PATIENTS AND METHODS: We reviewed all acute type A aortic dissections that were surgically managed in our institution from 1 January 1990 to 31 December 2000. Survival outcome and characteristics potentially associated with survival were abstracted from patient records. We screened preoperative electrocardiograms (ECG) and anticoagulant therapy. RESULTS: ST segment elevation incidence was 14% and preoperative anticoagulant therapy occurred in 63 (20%) cases as follow: aspirin 12%, aspirin + heparin 6%, thrombolysis 1%. Overall mortality was 22%. Time between pain and surgery was not statistically different between anticoagulant therapy and standard group. Administration of antithrombotic agents before admission in -hospital increased significantly mortality (Odds ratio (OR) = 2.02; IC [1.1-3.71]; p = 0.023). Other risk factors for death were preoperative circulatory failure (OR = 8.28 [4.23-16.24], p < 0.0001), preoperative cardiac arrest (OR = 21.92 [7.16-67.14], p < 0.0001), preoperative circulatory arrest (OR = 2.79 [1.60-4.88], p = 0.0003), preoperative cerebral perfusion (OR = 2.45 [1.18-5.05], p = 0.016), postoperative circulatory failure (OR = 3.37 [1.85-6.17], p < 0.0001), postoperative cardiac arrest (OR = 9.92 [3.49-28.21], p < 0.0001), postoperative serum creatinine >150 micromol/l (OR = 4.55 [2.43-8.50], p < 0.0001), postoperative dialysis (OR = 5.63 [2.44-13.20], p < 0.0001), more than 7 days of post-operative ventilation (OR = 23.44 [12.0-45.7], p < 0.0001). DISCUSSION: In our experience, 20% of acute type A aortic dissections had received a preoperative anticoagulant therapy. This event is an independent risk factor of in-hospital death and is more frequent in case of ischaemic ECG abnormalities.

Aged↗
PubMed2004

[What can be expected from off-pump coronary artery surgery?].

Coronary artery bypass surgery with beating heart (off-pump) has become more common in the last ten years allowing seven randomized studies with at least 60 patients, comparing off-pump and on-pump coronary bypass. Anaesthesia, monitoring and haemodynamic complications are described. Randomized studies concluded to less elevation of biochemical markers of myocardial and renal injury, less hydric inflation, less cerebral microemboli, reduction of homologous blood transfusions, of hospital stay and global costs. However in low risk patients no reduction in myocardial infarction, atrial fibrillation, stroke, acute renal failure, early reoperation, surgical site infection and mortality were observed. Non-randomized studies suggest a benefit in stroke and mortality in elderly patients but the possibility of incomplete revascularization remains.

Anesthesia↗
PubMed2003

Alteration of the left ventricular contractile reserve in heart transplant patients: a dobutamine stress strain rate imaging study.

BACKGROUND: Strain rate imaging (SRI), a recently developed Doppler-derived process, allows quantification of myocardial systolic function. We investigate whether SRI quantifies the contractile reserve during dobutamine stress tests in heart transplant patients (HT), when compared with normal individuals. METHODS: An incremental dobutamine test (5 to 40 microg/kg per minute) was performed in 10 HT and 15 control subjects, all of whom displayed normal coronary angiography. Gray-scale and color myocardial Doppler data were acquired in standard B-mode views at baseline, low-dose, peak, and recovery. Longitudinal SR was processed from the myocardial velocities for each segment. The changes in maximal systolic SR were used to quantify myocardial contractile reserve. RESULTS: Dobutamine infusion failed to induce clinical symptoms or electrocardiographic (ECG) changes in either group. Visually determined wall motion score was considered normal in all segments for each stage of the dobutamine stress. Heart rate was augmented similarly in both groups during dobutamine infusion. In controls, systolic SR increased gradually with incremental dobutamine dose and returned to baseline values upon recovery. Conversely, in HT patients, the increase in systolic SR was blunted at peak dobutamine, at which point it was significantly different vs controls. CONCLUSIONS: Quantitative assessment of myocardial function using SRI during dobutamine stress revealed an impaired contractile reserve in HT patients with normal coronary angiography. These subtle changes in regional myocardial function could not be identified using visual wall motion scoring. Additional studies are necessary to evaluate whether SR imaging detection of contractile reserve impairment will improve clinical efficiency or event prediction in this population.

Adrenergic beta-Agonists↗
PubMed2003

Evaluation of the estimation of midazolam concentrations and pharmacokinetic parameters in intensive care patients using a bayesian pharmacokinetic software (PKS) according to sparse sampling approach.

The aim of the study was to assess the performance of a bayesian program (PKS System, Abbott) for predicting midazolam concentrations and pharmacokinetic parameters in intensive care patients by comparing the pharmacokinetic parameters estimated by PKS to those calculated according to rich data. The study involved 42 patients receiving midazolam infusion for two hours or for several days. The program was used to predict plasma midazolam concentrations after feedback of 1, 2 or 3 concentrations. High correlation between observed and estimated concentrations was shown (r(2) > 0.992). Mean prediction error, mean absolute prediction error and root mean squared error were low for the patients of the reference and validation groups. From two or three feedback concentrations, midazolam pharmacokinetic parameters estimated by PKS were statistically comparable with those obtained using a rich pharmacokinetic analysis (P > 0.05 paired Wilcoxon test). Thus, PKS is useful for predicting midazolam concentrations and pharmacokinetic parameters when at least two feedback concentrations are known. This software seems to be appropriate for providing significant help to the clinician for midazolam dosage adjustment, according to midazolam concentrations and clinical sedation.

Area Under Curve↗
PubMed2002

[Antibiotic prophylaxis in cardiac surgery: practice patterns].

OBJECTIVE: To assess the prescription patterns in French and foreign centres for antibiotic prophylaxis in cardiac surgery. MATERIAL AND METHODS: Phone and written surveys concerned 64 French and 70 foreign centres. It focused on the first injection, the duration of treatment and the recommended agents. RESULTS: 87% of the French centres and 67% of the foreign centres answered the questionnaire. The first injection took place at anaesthesia induction in all French centres but during administration of premedication in 11% of foreign centres (p < 0.05). The duration of prophylaxis was restricted to the intraoperative period only in 20% and 15% of centres, respectively (ns), as specified by the recommendations. No French centres carried on the antibiotics more than 48 h versus 11% of foreign centres (p < 0.05). Cephalosporines of the second generation were prescribed in 84 and 49% of centres, respectively (p < 0.05). The combination of two antibiotics was less frequent in France than in foreign countries (5 versus 17%, p < 0.01). In absence of betalactamin allergy glycopeptides were not utilized in France versus 8% in foreign countries (p < 0.05). In case of allergy vancomycin was used in 66% of French and 42% of foreign centres. CONCLUSION: The French recommendations may have influenced favourably the antibiotic choice but the prophylaxis duration was too long in most of the non French European centres.

Antibiotic Prophylaxis↗
PubMed2002

[Sedation induced by midazolam in intensive care: pharmacologic and pharmacokinetic aspects].

OBJECTIVE: Review on midazolam in order to optimize drug utilisation and therapeutic monitoring. DATA SOURCES: Research of English or French articles published until August 2001, using Medline database. The key words were: midazolam, pharmacokinetics, pharmacodynamic, sedation, drug interaction. STUDY SELECTION: Original articles, clinical cases and letters to the Editor were selected. Animal studies were excluded. DATA EXTRACTION: The articles were analysed according to their interest in midazolam clinical practice. DATA SYNTHESIS: Midazolam is a benzodiazepine widely used in intensive care unit, as a sedative, anxiety-relieving, and amnesic drug. Midazolam could be used in patients with cardiac, or respiratory failure, and in neurosurgery. A great interindividual variability on pharmacokinetic and pharmacodynamic response was observed. In intensive care patients, elimination half-life is known to be widely increased. Midazolam is metabolised by hepatic microsomes. The major metabolite is the 1-hydroxymidazolam, which is pharmacologically active. A prolonged sedation due to an accumulation of conjugated metabolite was observed in renal failure patients. Enzymatic inductors or inhibitors could influence pharmacokinetics and pharmacodynamic effects of midazolam. CONCLUSION: According to midazolam pharmacokinetic and pharmacodynamic variability, an individual dosage adjustment is essential for long-term sedation. Target controlled sedation could be a mean to limit the variability and to reach quickly the pharmacodynamic effect.

Critical Care↗
PubMed2002

[Use of midazolam in postoperative sedation of patients with multiple organ failure treated with hemodiafiltration. Clinical study and pharmacokinetics].

OBJECTIVES: Evaluate the risk of accumulation of midazolam and conjugated 1-hydroxy-midazolam in high-risk ICU patients treated by continuous veno-venous haemofiltration. STUDY DESIGN: A prospective pharmocokinetic and clinical evaluation in 11 patients, with hepatic and renal failure. METHODS: Midazolam and metabolites were dosed in plasma and ultratiltration liquid by chromatography. Sedation was assessed by a simplified Ramsay score (EDS) with 4 levels. RESULTS: The mean duration of continuous infusion was 11 +/- 6 days. Peak plasma levels were over 150 ng ml-1 during the first 3 days, but normalized after that, only by drug adjustment based on scoring and clinical observation. There was no progressive accumulation of OH-midazolam, in spite of high levels (> 1000 ng ml-1). The Sieving coefficient (S) was 0.11 +/- 0.10 and 0.44 +/- 0.15 for midazolam and conjugated OH-midazolam respectively. A significant clearance (9.6 +/- 1.9 ml min-1) was observed for the conjugated products. T 1/2 beta was 11 h and was correlated with the mean time of recovery. A significant correlation was found between sedation score and both midazolam (r = 0.47) and OH-midazolam (r = 0.32). CONCLUSION: OH-midazolam risk of accumulation and significant clearance by haemodiafiltration should be taken into account in the drug adjustment in patients treated by continuous veno-venous haemofiltration.

Adjuvants, Anesthesia↗
PubMed2002

Pharmacological preconditioning: comparison of desflurane, sevoflurane, isoflurane and halothane in rabbit myocardium.

BACKGROUND: Recent investigations showed that isoflurane can induce pharmacological preconditioning. The present study aimed to compare the potency of four different halogenated anaesthetics to induce preconditioning. METHODS: Anaesthetized open-chest rabbits underwent 30 min of coronary artery occlusion followed by 3 h of reperfusion. Before this, rabbits were randomized into one of five groups and underwent a treatment period consisting of either no intervention for 45 min (control; n = 10), or 30 min of 1 MAC halogenated anaesthetic inhalation followed by 15 min of washout. End-tidal concentrations of halogenated agents were 3.7% for sevoflurane (n = 11), 1.4% for halothane (n = 9), 2.0% for isoflurane (n = 11), and 8.9% for desflurane (n = 11). Area at risk and infarct size were assessed by blue dye injection and tetrazolium chloride staining. RESULTS: Mean (SD) infarct size was 54 (18)% of the risk area in untreated controls and 40 (18)% in the sevoflurane group (P > 0.05, ns). In contrast, mean infarct size was significantly smaller in the halothane, isoflurane, and desflurane groups: 26 (18)%, 32 (18)% and 16 (17)%, respectively (P < 0.05 vs control). CONCLUSIONS: Halothane, isoflurane and desflurane induced pharmacological preconditioning, whereas sevoflurane had no significant effect. In this preparation, desflurane was the most effective agent at preconditioning the myocardium against ischaemia.

Anesthetics, Inhalation↗