Search PubMed⌕ Search

Biomedical subjects

D Chassard

Publications and source records attributed to D Chassard.

At least 73 records · Page 4Linked to original sources
PubMed1996

Cricoid pressure decreases lower oesophageal sphincter tone in anaesthetized pigs.

PURPOSE: Previous studies have shown a decrease of lower oesophageal sphincter (LOS) tone during stimulation of the upper oesophageal sphincter. Therefore, we hypothesized that during anaesthesia, cricoid pressure could result in a decrease in LOS pressure. METHODS: The LOS and oesophageal barrier pressures (BrP = LOSP minus gastric pressure) were obtained in 11 anaesthetized pigs with intraabdominal pressure of 15 mmHg using a manometric method (perfused catheters) before and during firm application of cricoid pressure. Reflux was assessed with concomitant recording of the lower oesophageal pH. RESULTS: Cricoid pressure decreased LOSP from 31.0 +/- 14.5 mmHg to 26.1 +/- 12.7 mmHg (P < 0.001) leading to a 35% reduction of oesophageal barrier pressure (9 +/- 10.3 mmHg vs 13.7 +/- 12.4 mmHg; P < 0.001). No episodes of reflux were recorded. CONCLUSIONS: This study shows that cricoid pressure decreases LOS tone in anaesthetized pigs. Although no gastrooesophageal reflux was recorded, this study suggests that, if cricoid pressure does not completely occlude the oesophagus, the decrease of oesophageal barrier pressure induced could favour the appearance of pulmonary aspiration.

Anesthesia↗
PubMed1996

[Effects of anesthesia on the lower sphincter of the esophagus].

The lower oesophageal sphincter (LOS) is the most important structure preventing regurgitation of gastric contents, with the risk of tracheobronchial aspiration, as it occurs in cases of laryngeal incompetence in connection with general anaesthesia. This article reviews anatomical data, means of assessment of the sphincter function, as well as the effects of anaesthetic agents and situations carrying a high risk of regurgitation and tracheobronchial aspiration.

Adjuvants, Anesthesia↗
PubMed1996

[Gynecologic laparoscopy with or without curare].

OBJECTIVE: To assess physiological changes and operating conditions during general anaesthesia with or without neuromuscular blockade in patients undergoing gynaecologic laparoscopy. STUDY DESIGN: Prospective, randomized, double-blind study. PATIENTS: Fifty non-obese patients, mean age 31 years, randomly allocated into either a group of 25 with curare (AC) or a group of 25 without curare (SC). METHODS: All patients were anaesthetized with propofol (2.5 mg.kg-1), sufentanil (0.4 microgram.kg-1) midazolam (2 mg) and N2O-O2. In addition, those of the AC group were given atracurium 0.25 mg.kg-1 for intubation, followed by additional boluses to maintain twitch height < 10% of the control value. Blood pressure, heart rate, peak airway pressure, end-tidal carbon dioxide pressure were recorded before and during pneumoperitoneum maintained at a pressure of 15 mmHg. Operating conditions were assessed at 10-min intervals, using a four point scale. RESULTS: In both groups, blood pressure and heart rate decreased following induction. The decrease in blood pressure was more important in the SC group at 5 min and before pneumoperitoneum (25 vs 15%); P < 0.05). The time course of PETCO2 and peak airway pressures were similar between groups. Operating conditions were not influenced by the muscle relaxant. CONCLUSIONS: Neuromuscular blockade influences neither most of the clinical haemodynamic and respiratory changes induced by pneumoperitoneum for gynaecologic laparoscopy not the operating conditions.

Adult↗
PubMed1996

Effect of pneumoperitoneum and Trendelenburg position on gastro-oesophageal reflux and lower oesophageal sphincter pressure.

We have measured the effect of pneumoperitoneum and the Trendelenburg position on lower oesophageal sphincter (LOSP) and barrier pressures (BrP) in 11 anaesthetized pigs while measuring the incidence of gastro-oesophageal reflux with a pH electrode. Propofol in combination with sufentanil had no effect on LOSP or BrP. Adoption of the Trendelenburg position with a pneumoperitoneum of 15 mm Hg resulted in a significant increase in LOSP (P < 0.002) and BrP (P < 0.001). However, in two of 11 pigs who had the lowest LOSP before induction, there was regurgitation.

Anesthesia, General↗
PubMed1996

Calcium homeostasis during i.v. infusion of 1.5% glycine in anaesthetized pigs.

We have examined changes in plasma concentrations of calcium in seven anaesthetized pigs during i.v. infusion of irrigating fluid containing 1.5% glycine. Volumes infused were 875 ml at 20 min (22 ml kg-1), 1475 ml at 40 min and 2075 ml at 60 min (75 ml kg-1). Plasma concentrations of sodium decreased from 134.5 (SD 3.4) to 112.8 (6.7) mmol litre-1 at 60 min and correlated with the volume of glycine infused (r2 = 0.73; P < 0.0001). Changes in total calcium concentrations were not statistically significant. A decrease in ionized calcium concentration was observed at 40 min (1.12 (0.05) vs 1.24 (0.04) mmol litre-1; P < 0.05) and reached 1.11 (0.05) mmol litre-1 at 60 min (P < 0.01). However, when corrected for pH, this decrease was not statistically significant. These results suggest that changes in plasma concentrations of sodium rather than changes in calcium homeostasis are probably more important in the development of transurethral prostatic syndrome.

Anesthesia, General↗
PubMed1996

Extradural clonidine combined with sufentanil and 0.0625% bupivacaine for analgesia in labour.

We have studied the use of clonidine combined with low doses of sufentanil and bupivacaine in 45 parturients requiring extradural analgesia for the first stage of labour, in a double-blind, randomized study. We gave 0.0625% bupivacaine 10 ml containing 1:200,000 adrenaline and sufentanil 10 micrograms (1 ml) to which was added 0.9% saline, or clonidine 100 or 150 micrograms (1 ml). We compared the quality (VAS scores) and duration of analgesia, motor block, maternal haemodynamic state (mean arterial pressure and heart rate) and fetal and maternal side effects. Mean duration of anaesthesia was prolonged slightly: 105 (SD 21) min without clonidine, 130 (26) min with clonidine 100 micrograms (P < 0.05 vs control) and 144 (40) min with clonidine 150 micrograms (P < 0.01 vs control, ns vs 100 micrograms). There were no differences in VAS scores, onset times, heart rate, ventilatory frequency, motor block, sedation, pruritus or bradycardia between the groups. Analgesia was associated with a reduction in mean arterial pressure with clonidine. However, these adverse side effects were of minor clinical importance regardless of the extradural clonidine dose, except for a high incidence of fetal heart tracing abnormalities when clonidine 150 micrograms was used. These effects associated with a limited effect on analgesia may curtail the widespread use of clonidine as an adjunct to extradural 0.0625% bupivacaine with sufentanil 10 micrograms during labour.

Adrenergic alpha-Agonists↗
PubMed1996

Effect of halothane, isoflurane and desflurane on lower oesophageal sphincter tone.

We have studied the effects of volatile anaesthetics on lower oesophageal sphincter (LOS) tone in three groups of eight pigs allocated randomly to receive end-tidal concentrations of 0.5, 1.0 and 1.5 MAC of desflurane, isoflurane or halothane for 15 min. LOS and oesophageal barrier pressures (BrP = LOSP - gastric pressure) were measured using a manometric method. The decrease in BrP paralleled the decrease in LOS pressure and was significant at 0.5 MAC for isoflurane and at 1.0 MAC for halothane. At 1.5 MAC, BrP values were approximately 62% of baseline values for halothane, 37% for isoflurane and 83% for desflurane. Inter-group comparisons showed that BrP did not differ at baseline and at 0.5 MAC. At 1.0 MAC the effect of isoflurane on BrP was significantly different from desflurane (P < 0.001) and halothane (P < 0.02) whereas the effect of desflurane on BrP was not significantly different from halothane. At 1.5 MAC the effect of isoflurane on BrP was significantly different from desflurane (P < 0.01) and halothane (P < 0.05) whereas the effect of desflurane on BrP was not significantly different from halothane. We conclude that desflurane maintained BrP and this may be clinically important in patients at high risk of regurgitation.

Anesthetics, Inhalation↗
PubMed1996

The effect of increase in end-tidal carbon dioxide on lower esophageal sphincter tone.

The lower esophageal sphincter is composed of smooth muscles and is the main barrier against regurgitation during anesthesia. As smooth muscles are usually sensitive to CO2, we investigated the response of lower esophageal sphincter pressure to varying concentrations of CO2 in six anesthetized pigs using a manometric method. CO2 was increased by increasing the dead space at the Y piece of the ventilator. Basal values for ETCO2 were 35 +/- 2 mm Hg, reaching 62 +/- 1 mm Hg at the end of the study (P < 0.03). In response to the increase in ETCO2, no change in lower esophageal sphincter pressure was noted (12 +/- 3 mm Hg vs 13 +/- 4 mm Hg). These findings indicate that the lower esophageal sphincter is not affected by CO2 in the range usually encountered in clinical practice.

Anesthesia↗
PubMed1996

The effects of neuromuscular block on peak airway pressure and abdominal elastance during pneumoperitoneum.

Administration of muscle relaxants is considered as necessary to prevent high intraabdominal and peak inspiratory pressures induced by pneumoperitoneum during laparoscopy. In the present study, we hypothesized that neuromuscular block does not alter pulmonary or abdominal elastic properties in pigs receiving general anesthesia. To test this hypothesis, changes in peak airway pressure and abdominal elastance during intraabdominal CO(2), insufflation from 0 to 15 mm Hg were recorded in anesthetized pigs, with or without muscle relaxants. A 100% increase in peak inspiratory airway pressure was obtained. This was unaffected by neuromuscular block induced by atracurium (13.2 +/- 5.0 mm Hg vs 25.0 +/- 4.8 mm Hg for the control group and 12.6 +/- 5.0 mm Hg vs 23.5 +/- 6.2 mm Hg for the paralyzed group). Abdominal pressure/volume relationships were independent of muscle relaxant administration (calculated elastance was 3.98 +/- 1.56 mm Hg/L without muscle relaxant vs 3.86 +/- 1.37 mmHg/L in the atracurium group). We conclude that high peak inspiratory airway pressures and intraabdominal pressures during laparoscopy are not affected by neuromuscular block. These findings also question the necessity of muscle relaxants in clinical anesthetic practice during laparoscopic surgery.

Abdomen↗
PubMed1996

Cytokine and hormonal changes after cholecystectomy. Effect of ibuprofen pretreatment.

OBJECTIVE: Surgical stress induces hormonal and cytokine responses proportional to the extent of the injury. Therefore, the authors assessed the effect of ibuprofen pretreatment on metabolic and hormonal changes after surgery. SUMMARY BACKGROUND DATA: Postoperative administration of cyclo-oxygenase inhibitor reduces cytokine production and nitrogen losses. METHODS: The authors studied the plasma hormones and metabolic and cytokines changes after perioperative ibuprofen administration in 22 patients undergoing cholecystectomy under inhalational anesthesia. Suppositories containing ibuprofen (500 mg) or placebo were administered 12 and 2 hours before surgery, and every 8 hours until the third postoperative day. Blood samples were collected 24 and 2 hours before surgery and 2, 4, 6, 24, 48, and 72 hours after surgery for glucose, C-reactive protein, leukocytes, adrenocorticotropic hormone (ACTH), cortisol, tumor necrosis factor, and interleukin-1 and interleukin-6 determinations. RESULTS: In both groups, plasma cortisol levels remained elevated for 3 days, whereas plasma ACTH levels returned to the basal level at day 1. The ACTH (p < 0.01), cortisol (p < 0.01), and glucose changes (p < 0.001) were smaller in the ibuprofen group and their duration was shorter. The interleukin-6 levels increased gradually after skin incision until the sixth hour and were significantly lower (p < 0.05) in the ibuprofen group. CONCLUSION: Ibuprofen pretreatment in perioperative course is able to reduce the endocrine response and cytokine release. Therefore, ibuprofen may be useful in decreasing the stress response in severely surgical patients.

Adult↗
PubMed1996

Influence of body compartments on propofol induction dose in female patients.

BACKGROUND: For induction of anaesthesia, drugs such as propofol are commonly administered according to a per weight basis. However, drugs are primarily distributed to the fat-free mass. This study was undertaken to determine the relationship between propofol requirement for induction and body mass determined by bioimpedance analysis (BIA) or by body mass index (BMI). METHODS: Twenty-one ASA 1 female patients scheduled for gynaecologic surgery received propofol for induction at 133 mg.min-1. Stepwise regression analysis was used to describe the relationships between propofol requirement for loss of consciousness and age, body weight, and lean body mass measured by BIA and BMI (independent variables). RESULTS: Loss of consciousness was obtained with a propofol dose (Mean (SEM)) of 2.17 +/- 0.10 mg.kg-1. Stepwise analysis showed that propofol requirement (total dose) was not proportional to weight or age but related to lean body mass as determined by BIA and to body mass index (r2 = 0.447; global P- value < 0.007). BMI was the only regressor variable when the propofol dose was expressed in mg.kg-1 (r2 = 0.661; P < 0.001). CONCLUSIONS: Our results indicate that propofol requirements for induction are proportional to the lean body mass rather than total body weight.

Adult↗
PubMed1994

[Gastroduodenal tolerance of methylprednisolone. Study of oral versus intravenous administration in healthy volunteers].

OBJECTIVES: To endoscopically evaluate the tolerance of gastroduodenal mucosa to methylprednisolone given orally and intravenously. METHODS: Thirty two healthy volunteers (age range 18-39 years) were divided randomly into two groups of 16 each (8 males and 8 females). All were Caucasians, gave their informed consent and were considered normal after a complete clinical and laboratory work-up including gastroduodenal fibroscopy. Methylprednisolone (500 mg) was administered for three consecutive days at 9 a.m., orally in one group and intravenously in the second group. No other drugs were being taken and alcohol and smoking were prohibited from day 0 to day 11. Tolerance was evaluated on days 4 and 11 based on clinical examination, blood pressure, heart rate, oral temperature, body weight, blood and urine chemistry and by video-recorded gastroduodenal endoscopy. Two independent endoscopists, uninformed of the patient's regimen, scored lesions from 0 (normal) to 5 (more than 25 lesions including at least 2 erosions). In case of abnormal findings, follow-up was continued to normalization. RESULTS: Endoscopically detectable lesions (stage I) attributed to corticosteroid therapy were observed in 4 subjects in the oral group and in 5 in the intravenous group. All regressed spontaneously. Duodenal lesions were observed only after oral administration while lesions of gastric mucosa were mostly found after intravenous administration. Systemic effects included abdominal pain after oral intake, 1 case of insomnia and bitter taste in the mouth after intravenous administration. CONCLUSIONS: These findings suggest that the effect of corticosteroid therapy, on the gastric mucosa, is basically systemic, and on the duodenal mucosa, basically local. No severe manifestations were observed after high-dose methylprednisolone given orally or by intravenous injection.

Administration, Oral↗
PubMed1994

Pharmacokinetics of sparfloxacin in humans after single oral administration at doses of 200, 400, 600, and 800 mg.

The pharmacokinetics of sparfloxacin at oral doses of 200, 400, 600, and 800 mg were studied in 12 healthy volunteers in a randomized double-blind crossover study. Each dose administration was separated by a 1-week washout period. Plasma and urine samples were collected up to 120 hours postdosing, for determination of free and total (free plus glucurono-conjugated) sparfloxacin levels by high-performance liquid chromatography assay and ultraviolet detection. Mean Cmax values ranged from 705 +/- 158 to 1966 +/- 620 ng/mL for the 200 to 800 mg doses, at median tmax ranging from 4 to 5 hours. A slight decrease of sparfloxacin bioavailability with increasing dose was observed because AUC was 87% to 88% of the expected area when the dose was doubled. The elimination half-life values were constant over the dose range (with values ranging from 18 to 21 hours) as well as the renal clearance. The metabolic ratio conjugated/free drug was not modified by increasing dose.

Administration, Oral↗
PubMed1994

[In vitro effects of the alkalinization of 0.25% bupivacaine and 2% lidocaine].

Recent clinical studies have suggested that alkalinization of local anaesthetic agents may shorten the onset time and lengthen their duration of action. In clinical practice, sodium bicarbonate 1.4 and 4.2% are often added to local anaesthetic agents to obtain these effects. We evaluated pH changes of 4 local anaesthetic solutions commonly used for obstetrical epidural anaesthesia, in order to develop titration curves with sodium bicarbonate 1.4 and 4.2%. Local anaesthetic agents tested included lidocaine 2% and bupivacaine 0.25% with and without epinephrine. Each one was divided in 10 mL aliquots, and supplemented with 25 micrograms of sufentanil (1 mL). The pH measurement were made with a pH-meter P 500 with a combined electrode (TBC 12/HS) in the standard solution and after incremental addition of 0.5 mL of 1.4 or 4.2% sodium bicarbonate. The percentage of the free form of local anaesthetic was calculated for each step, using the Henderson-Hasselbalch equation. Results showed that alkalinization is not beneficial with epinephrine free solutions. Increasing volumes of sodium bicarbonate, buffered the acidic effect of sodium bisulfite present in solutions containing epinephrine, and increased the percentage of the free form of local anaesthetic to the level of epinephrine free solutions. From this pH point upwards, the gain is poor and precipitates are generated. This study suggests that 1 mL of 4.2% sodium bicarbonate for 10 mL of local anaesthetic solution is the best theorical choice for alkalinization of a local anaesthetic associated with epinephrine.

Adult↗
PubMed1994

Pharmacokinetics and metabolism of amopyroquin after administration of two doses of 6 mg/kg im 24 h apart to healthy volunteers.

Twelve healthy volunteers received two doses of amopyroquin 6 mg/kg im 24 h apart. Blood and plasma concentrations of amopyroquin and two metabolites were assayed by HPLC from 0 to 48 h. Half-life values for amopyroquin, calculated from 0 to 48 h whole-blood and plasma samples were 13.9 +/- 9.1 and 18.3 +/- 6.8 h respectively. Two metabolites were detected in blood and they had very low in-vitro activity against Plasmodium falciparum compared with the parent drug. Neither hypotension nor lengthening of QRS complex were observed in any volunteers and hepatic enzymes remained in the normal range despite a transitory increase. These results confirm that unchanged amopyroquin accounts for antimalarial activity in vivo and that two doses of 6 mg/kg are well tolerated.

Adult↗
PubMed1994

Effects of intravenous medium-chain triglycerides on pulmonary gas exchanges in mechanically ventilated patients.

OBJECTIVE: In mechanically ventilated patients, pulmonary gas exchange was investigated during the administration of total parenteral nutrition containing medium-chain triglycerides or long-chain triglycerides as fat emulsions. DESIGN: Prospective, randomized, crossover trial (two lipid infusion periods of 8 hrs). SETTING: Intensive care unit in a university hospital. PATIENTS: Six mechanically ventilated patients, using the pressure-support mode. INTERVENTIONS: Total caloric intake was adapted according to measured energy expenditure. Fat emulsion provided 50% of the energy expenditure. Patients were infused with 50% medium-chain/50% long-chain triglycerides or 100% long-chain triglycerides in a random sequence. MEASUREMENTS AND MAIN RESULTS: Oxygen consumption, CO2 production, and minute ventilation were measured by indirect calorimetry. PaO2 and PaCO2 were determined in blood samples. Medium-chain triglycerides increased oxygen consumption by 27.8% and minute ventilation by 14.3% at the end of the protocol. CO2 production, PaO2, and PaCO2 were not different between groups. CONCLUSIONS: Medium-chain triglycerides cause an increase in metabolic demand in mechanically ventilated patients when they are infused over a short period. Postoperative or intensive care unit patients with a low pulmonary reserve should receive infusions of medium-chain triglycerides over a more prolonged period than long-chain triglycerides.

Aged↗