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Biomedical subjects

D Benhamou

Publications and source records attributed to D Benhamou.

At least 19 recordsLinked to original sources
PubMed1992

Serum concentrations of local anaesthetics following intraperitoneal administration during laparoscopy.

The present study is a comparison of the pharmacokinetics of four local anaesthetics injected double blind in the right subdiaphragmatic area during outpatient laparoscopy performed under standard general anaesthesia in 28 young women. 80 ml of one of the following solutions was injected: Group A 0.5% plain lidocaine (n = 7), Group B 0.5% lidocaine with 1/320.000 adrenaline (n = 8), Group C 0.5% lidocaine with 1/800.000 adrenaline (n = 7), and Group D 0.125% bupivacaine with 1/800.000 adrenaline (n = 6). Blood samples were collected over 360 min from an iv catheter and serum concentrations were measured by gas chromatography. No adverse effects occurred in the study period. In Group A (plain lidocaine), Cmax was significantly higher and tmax significantly earlier than in Groups B and C (lidocaine with adrenaline). A toxic level was not found after either solution in any patient. The intraperitoneal use of doses of 400 mg lidocaine or 100 mg bupivacaine for perioperative analgesia was safe and solutions of lidocaine containing adrenaline appeared to pose even less risk than plain solutions.

Adult↗
PubMed1992

Comparison of hypertonic saline (5%), isotonic saline and Ringer's lactate solutions for fluid preloading before lumbar extradural anaesthesia.

We have compared the haemodynamic effects of fluid preloading performed before lumbar extradural anaesthesia with isotonic saline (NS), 5% hypertonic saline (HS) and Ringer's lactate (RL) solutions in 30 ASA I patients undergoing minor orthopaedic surgery, allocated randomly to the three groups. All patients received an equal amount of sodium (2 mmol kg-1). After fluid preloading, lumber extradural anaesthesia was performed (2% lignocaine 6 mg kg-1) and ephedrine was administered in order to maintain mean arterial pressure (MAP) > 80% of its control value. Both volume and duration of fluid preload were significantly less in group HS (160 (SD 25) ml, 8.8 (SD 2.9) min) than in the two other groups (NS: 903 (144) ml, 17.7 (3.3) min; RL: 932 (166) ml, 212 (6.0) min) (P < 0.05). The number of blocked segments and the total amount of ephedrine administered were similar in the three groups. Heart rate increased significantly in all groups immediately after the fluid preload and remained increased until the end of the study (90 min). MAP was not affected by any fluid preload and its maximal decrease after lumbar extradural anaesthesia was similar in all groups. Infusion of 5% HS 2.3 ml kg-1 was tolerated well and produced a significant (P < 0.05) but moderate hypernatraemia lasting 90 min after the end of fluid preloading. We conclude that HS may be useful when rapid fluid preloading is desired, in situations where excess free water administration is not desired.

Adult↗
PubMed1992

Ventilatory effects of epidural clonidine during the first 3 hours after caesarean section.

Many authors have shown the analgesic efficacy of 150-800 micrograms of epidural clonidine in the postoperative period. Its use as an analgesic after caesarean section has recently been studied with higher dosages (400-800 micrograms). Our study aimed at assessing the analgesic and ventilatory effects of two smaller doses of epidural clonidine (150 and 300 micrograms), which were compared to the effects of 10 mg of parenteral morphine (M) during the first 3 h after caesarean section. The duration of the analgesic effect was longest with 150 micrograms of epidural clonidine. Arterial blood pressure decreased from 30 min after the injection to the end of the study in both epidural clonidine groups. A marked sedation was observed in patients receiving 300 micrograms of epidural clonidine and was frequently associated with snoring, obstructive apnoea and episodes of arterial oxygen desaturation. We conclude that 150 micrograms of epidural clonidine provides better and longer analgesia after caesarean section than 10 mg of parenteral morphine, and seems preferable to higher doses (300 micrograms) in this setting, since 300 micrograms of epidural clonidine may produce unacceptable respiratory obstructive disturbances.

Analgesia, Epidural↗
PubMed1992

Respiratory effects of epidural sufentanil after cesarean section.

The ventilatory response to CO2 was measured to evaluate the degree of respiratory depression after epidural sufentanil. After cesarean section performed with bupivacaine epidural anesthesia, 14 patients received either 30 micrograms (n = 7) or 50 micrograms (n = 7) of epidural sufentanil. Respiratory measurements were made before and 15, 45, and 120 min after sufentanil injection. The presence and severity of sedation and other nonrespiratory side effects were evaluated throughout the study. Plasma sufentanil assays were performed on blood samples obtained at frequent intervals during the first 2 h. Although changes in resting ventilation did not occur, both sufentanil doses depressed the ventilatory response to CO2. After sufentanil 30 micrograms, the slope of the CO2 response curve decreased significantly at 45 and 120 min (control value, 2.33 +/- 0.3 L.min-1.mm Hg-1 [mean +/- SEM] vs 1.61 +/- 0.24 and 1.72 +/- 0.15, respectively, P less than 0.05). After sufentanil 50 micrograms, significant decreases occurred at 15 and 45 min (control value, 2.84 +/- 0.71 vs 1.81 +/- 0.48 and 1.48 +/- 0.31 L.min-1.mm Hg-1, respectively). The mean maximal decrease in the slope occurred at 45 min and was more pronounced after 50 micrograms (-42.3% +/- 7.4%) than after 30 micrograms (-27.4% +/- 9.9%). Analgesia was similar in both groups. Side effects, particularly sedation, were more severe with the 50-micrograms dose. We conclude that 30 micrograms of epidural sufentanil is preferable to the higher dose with regard to both respiratory and nonrespiratory side effects. Even with the lower dose, monitoring of ventilation is advisable for a minimum of 2 h.

Adult↗
PubMed1992

Nasal mask ventilation in acute respiratory failure. Experience in elderly patients.

Nasal mask ventilation (NMV) has been used successfully in chronic restrictive respiratory failure and more recently in acute exacerbations of chronic obstructive pulmonary disease (COPD). This study aimed to evaluate the possible role of NMV in acute respiratory failure (ARF) episodes when mechanical ventilation with endotracheal intubation is questionable. Thirty patients (age, 76 +/- 8.1 years) were treated by NMV during ARF episodes (COPD, 20; other chronic respiratory failure [CRF], 5; chronic heart failure [CHF], 4). All patients were hypoxemic (PaO2, 5.85 +/- 1.62 kPa) and hypercapnic (PaCO2, 8.63 +/- 1.89 kPa) with respiratory acidosis (pH, 7.29 +/- 0.08). In all cases, clinical or physiologic parameters indicated the need for mechanical ventilation, but endotracheal intubation was either not applied because of the age and the physiologic condition of the patients (17 cases) or was postponed (13 cases). NMV was performed using a volume-cycled ventilator and a customized nasal mask. Ventilation was continuous during the first 12 hours and the following nights and was then intermittent during the day. Twenty-one patients improved clinically, within a few hours. Progressive correction of arterial blood gases was observed: PaO2 increased during the first hour, but PaCO2 decreased more slowly. Eighteen patients were able to be successfully weaned from NMV. Twelve patients failed to improve despite NMV: eight of them died and four required endotracheal intubation. There was no difference in the success rate between patients in whom endotracheal ventilation was contraindicated or postponed. Clinical tolerance was satisfactory in 23 patients and poor in seven patients. A return to the respiratory condition was observed in the surviving patients with subsequent discharge from hospital. NMV therefore successfully treated respiratory distress initially in 60 percent of the 30 patients. These results suggest that NMV could be a possible alternative in the treatment of ARF, even in very ill patients, when endotracheal ventilation is controversial or not immediately required.

Acute Disease↗
PubMed1992

[The shielded bronchial brush and transcutaneous tracheal puncture].

Specific bacteriological diagnosis is the first condition for optimal treatment in bacterial pneumonias. Despite many attempts to improve its reliability, bacteriological examination of the sputum is a non-sensitive and non-specific examination. Transtracheal aspiration (TTA) and bronchoscopic protected brush (BPB) are more reliable examinations but their practice is limited because of their invasive characteristic. Then treatment of non-critical pneumonia is often based on the probable organism. BPB is carried out using a protected brush with a double catheter which is introduced into the bronchial tree under fiberscopic control. Although easy, such a technique must be accurate in its performance. Even if good reliability of this method is well establish in in vitro and in vivo studies, it remains that false positive results have been described in clinical studies, so that quantitative cultures are needed. Results are evident in non-intubated patients without bronchial disease in which identifying the responsive germ is the only purpose. But in intubated ventilated patients two problems are faced: firstly on establishing a positive diagnosis of bacterial pneumonia and secondly on identifying the responsive germ. TTA technique prevents pollution of the specimen with oropharyngeal flora: bronchial secretions are aspirated by a catheter introduced into the trachea via percutaneous route through crico-thyroid membrane. Its performance is easy, quick and severe complications are very rare when usual contraindications are taken into account (severe hypoxia, hemostatic disorders). Being of good sensitivity, the TTA shows false positive results in patients with chronic bronchial diseases. On a bacteriological point of view, these protected techniques have to be used only when pyogenic bacteria are suspected. Invasive techniques are needed when there are factors of specific severity or other risk factors. The choice (TTA or PBP) depends mostly on medical habits and material availability.

Bacteria↗
PubMed1991

Ventilatory effects of premedication with clonidine.

Clonidine has been proposed as a premedication before surgery because of its beneficial effects on hemodynamics, especially in patients with a high cardiovascular risk. However, reports on the effects of clonidine on ventilation are conflicting. Accordingly, eight fasting ASA physical status I volunteers received in a double-blind randomized order 300 micrograms of oral clonidine, the effects of which were compared with placebo given in a crossover design. Hypotension, bradycardia, and sedation were significantly more profound and of longer duration after clonidine. Clonidine did not decrease minute ventilation more than the placebo, and separate analysis of tidal volume and respiratory rate changes also showed the absence of a significant difference between the two groups. However, clonidine produced episodes of obstructive pattern associated with moderate decreases in oxygen saturation, which were not observed with placebo. We conclude that the potential detrimental effects of these obstructive airway patterns of clonidine should be taken into account when prescribing this drug for premedication.

Administration, Oral↗
PubMed1990

Stability of epinephrine in alkalinized solutions.

STUDY OBJECTIVE: Increasing the pH of an epinephrine solution favors its oxidation and may result in a decrease in its biological activity. It is therefore generally assumed that epinephrine and sodium bicarbonate should not be infused in the same IV line during CPR. The aim of this study was to determine the validity of this widely accepted proposition. DESIGN AND SETTING: Two different commercial solutions of epinephrine differing only in the concentration of sodium metabisulfite (0.46% and 0.02%) were studied. Two dosages of each solution type (1 mg/1 mL and 10 mg/10 mL) were diluted in 250 mL of 8.4% sodium bicarbonate. MEASUREMENTS AND MAIN RESULTS: The concentration of epinephrine was measured at different times for two weeks. It was found that the concentration of epinephrine decreased slowly to zero after two weeks, and was approximately at 70% and 100% of control values at 30 minutes after alkalinization. CONCLUSION: It was concluded that epinephrine in an alkaline solution is effectively oxidized but has a slow reaction that may not be clinically relevant over short periods of time.

Bicarbonates↗
PubMed1990

[Postoperative analgesia after cesarean section: sublingual buprenorphine versus subcutaneous morphine].

This study aimed to compare the efficacy and side-effects of sublingual buprenorphine, a synthetic opioid agonist antagonist, with those of subcutaneous morphine. Fifty ASA class 1 patients were included in the study after having given their informed consent. Caesarean section was carried out under epidural block with 0.5% bupivacaine; no opioids were used during the procedure. The first dose of opioid was given 2 h after the first dose of bupivacaine. Patients were randomly given either 10 mg morphine (n = 25) or 0.4 mg buprenorphine (n = 25), followed by the same dose every 6 h for 36 h. When analgesia was insufficient, tablets containing dextropropoxyphene and paracetamol were given. No attempt was made to blind the study to the patient, but the investigator assessing pain was unaware of the drug given to the patient. Pain intensity was assessed before, and 2 h after each dose of opioid with a 100 mm visual scale, as well as systolic, diastolic and mean arterial blood pressures, heart and breathing rates, and SpO2. Side-effects (pruritus, nausea, vomiting, drowsiness) were also noted. In 2 patients in each group, the protocol was stopped before the 36th h, but after the fourth dose, either because of side-effects, or at the patient's request. Results were similar in both groups of patients, whether for degree of pain relief, or physiological effects. There was no clinically detectable respiratory depression. Duration and intensity of episodes of arterial oxygen desaturation, and the incidence of nausea, were similar in the 2 groups; pruritus was more common in the morphine group.(ABSTRACT TRUNCATED AT 250 WORDS)

Administration, Buccal↗
PubMed1990

Effects of age on plasma protein binding of sufentanil.

The plasma protein binding of sufentanil has been studied in newborns, infants (0.5 +/- 0.3 yr), children (6.8 +/- 3.0 yr), and adults (39.5 +/- 9.0 yr). Binding of sufentanil was determined in vitro by equilibrium dialysis, and radioactive tritiated sufentanil was used for the determination of drug concentrations in plasma and buffer. The free fraction of sufentanil was significantly higher in the newborn (19.5 +/- 2.7%; P less than 0.01) than in the other age groups. The free fraction was also significantly higher in infants (11.5 +/- 3.2%; P less than 0.01) than in children (8.1 +/- 1.4%) or in adults (7.8 +/- 1.5%) but did not differ significantly between children and adults. The free fraction of sufentanil was strongly correlated with the alpha 1-acid glycoprotein plasma concentration (r = -0.73; P less than 0.001) whereas it was weakly correlated with albumin plasma concentration (r = -0.35; P less than 0.05). These data suggest that the lower concentration of alpha 1-acid glycoprotein in newborns and infants probably accounts for the decrease in protein binding of sufentanil in these age groups when compared with that in older children or adults. The increased free fraction in the neonate might contribute to the enhanced effects of lipophilic opioids in the neonate.

Adult↗
PubMed1990

Factors influencing precipitation of pH-adjusted bupivacaine solutions.

Solutions of bupivacaine precipitate when bicarbonate is added. This limits the clinical use of pH-adjustment in optimizing bupivacaine activity. In this study four different bupivacaine solutions were studied with the addition of sodium bicarbonate at 4 degrees C or 20 degrees C. Bupivacaine concentrations remained unchanged after pH-adjustment. Least crystallization was observed with bupivacaine solutions containing a small amount of sodium bicarbonate and stored at 4 degrees C.

Bicarbonates↗
PubMed1988

Chemical stability of bupivacaine in pH-adjusted solutions.

Recent clinical studies have suggested that alkalinization of bupivacaine may shorten the time to onset and lengthen its duration of action. However, addition of sodium bicarbonate to commercially manufactured bupivacaine can rapidly produce precipitation. This study was performed to study the stability and precipitation of bupivacaine solutions 0.25% and 0.50% with and without epinephrine 1:200,000 after alkalinization. The results indicate that alkalinization does not increase precipitation above recommended limits and that the concentration of bupivacaine in solutions is maintained at least 6 h after alkalinization.

Bupivacaine↗
PubMed1988

Chemical stability of lignocaine (lidocaine) and adrenalin (epinephrine) in pH-adjusted parenteral solutions.

Recent clinical studies have shown that alkalinizing lignocaine (lidocaine) solutions is an effective way of shortening the time of onset and increasing the duration of anaesthesia. However, alkalinizing lignocaine solutions raises the problem of the stability of these preparations. Moreover, the adrenalin usually associated with it is unstable in alkalinized solutions designed for peridural injection. This study was performed to define the range of pH over which lignocaine and adrenalin in commercial solution is stable. The results indicate that it is possible to alkalinize lignocaine solutions and that the solutions prepared are stable for at least 6 h.

Drug Combinations↗