PubMed Health⌕ Search

Biomedical subjects

Y Nivoche

Publications and source records attributed to Y Nivoche.

17 recordsLinked to original sources
PubMed1992

[A study of 11 ventilators for anesthesia: laboratory testing].

Eleven anaesthesia ventilators were instrumentally tested under various conditions. They included: Excel and Modulus II Plus (Ohmeda); 710 and Servo anaesthesia circle 985 (Siemens); Jollytronic (Soxil) and Elsa (Engström); SA2 and Cicero (Dräger); ABT 4,300 (Kontron); Monnal A and the prototype Alys (Taema). The test circuit comprised a two compartment model lung, a pneumotachograph, a pressure gauge in the "airway". The volume was calculated as the integral of flow rate. Each machine was calibrated by the firms' technicians. Before each test, the pneumotachograph was calibrated using a 11 air syringe and the pressure gauge with a 5 cm water column. Each machine ventilated the model lung for 30 min before starting the tests. There were five tests: 1) reliability of the machine's spirometer, 2) reliability of the ventilation rate, 3) reliability of pressure measurements, 4) effect of increasing fresh gas flow on spirometry, 5) effect of increasing downstream resistances. In usual simulated ventilatory conditions, all the machines accurately delivered the setted ventilation and spirometric measurements were with minimal error only. Several ventilators (SA2, Excel, 710, Elsa, ABT 4,300) did not succeed in maintaining their performances when compliance was strongly decreased or resistance of the test lung notably increased. Resistance in the circuit during simulated spontaneous ventilation was < 3.6 cmH2O.l-1.s-1. Increasing fresh gas flow raised the minute volume delivered in six ventilators. It is concluded that, during extreme ventilatory conditions, the inspired volume must be adjusted so as to maintain the inspired tidal volume. However, ventilators which increase inspiratory time in response to an increased mechanical load cannot be adjusted by this way.

Anesthesia, Closed-Circuit↗
PubMed1991

[Anesthesia for heart catheterization in children. Comparison of 3 techniques].

A study was carried out to compare the haemodynamic and respiratory effects, as well as the quality of recovery, of anaesthesia with ketamine, sodium gamma-hydroxybutyrate (GOH) and etomidate in children undergoing cardiac catheterization. Thirty children, mean age 48 +/- 35 months, ranked ASA 2 or 3 on account of congenital heart disease, were assigned to one of three groups (n = 10). They were given: in group E1, a 0.3 mg.kg-1 bolus of etomidate, followed by 0.1 mg.kg-1.min-1 for 10 minutes, and 0.026 mg.kg-1.min-1 thereafter; in group G2, a 50 mg.kg-1 bolus of GOH, and in group K3, a 4 mg.kg-1 bolus of ketamine followed by a continuous infusion of 0.083 mg.kg-1.min-1. The patients breathed spontaneously. Monitoring included heart rate, systolic, diastolic and mean blood pressure, pulse oximetry, and capnography. Femoral venous or arterial catheterization was performed after local anaesthesia (with no more than 2 mg.kg-1 of lidocaine). Measurements were performed before induction, and then 1, 10, 30 and 60 minutes afterwards. The quality of anaesthesia was assessed according to Steward's scale. The investigation lasted between 50 and 100 min in all three groups. There were no significant differences in haemodynamic and respiratory parameters during the investigation between the groups. Recovery was shorter and of better quality in group E1. On the opposite, 30 minutes after the end of the catheterization, all the patients in group K3 were stuporous, with 5 of them displaying involuntary movements. The patients of the other two groups reacted correctly to stimuli, but those in group G2 went back to sleep very rapidly. There were no complications.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Intravenous↗
PubMed1991

[Pharyngolaryngeal fibroscopy under general anesthesia in children. Technique and indications in sleep apnea and hypopnea].

The frequency of obstructive sleep apnea syndromes in children is not negligible. The diagnosis is based on the parents' answers and on sleep recordings. Radiographs sometimes help defining the site of obstruction. However, except when there is a considerable, clinically obvious tonsillar hypertrophy (which is fortunately the most frequent case), the exact location of the obstruction may be difficult to assess. In fact, it is far less obvious and more often multiple than in adults, especially in cases of craniofacial malformation. A pharyngolaryngeal exploration technique with a flexible endoscope under general anesthesia (GA) has been developed in our department. With natural ventilation, when a GA is induced with halothane through a mask, muscular relaxation similar to that of natural sleep is obtained. A thin flexible endoscope is then inserted through the mask to observe the obstructive structures at the nasal, rhino/oropharyngeal or pharyngolaryngeal levels. During the past two years, 17 children were examined with this technique, which allows an extremely accurate diagnosis of the site of the obstruction. Four children had a craniofacial malformation. The examination evidenced 9 cases of adenotonsillar hypertrophy, 4 cases of dynamic laryngeal obstruction, 3 cases of basilingual obstruction and one case of circular collapse of the oropharynx. The evolution under treatment confirm the merits of this endoscopic examination technique for the etiological diagnosis of respiratory obstruction.

Anesthesia, General↗
PubMed1989

[Treatment of malignant hyperthermia crisis during anesthesia].

Malignant hyperthermia (MH), triggered by anaesthesia, is a rare and potentially fatal condition. It requires immediate and specific treatment. This review focuses on anticipation and organisation of treatment. Anticipation means that dantrolene should be available, that an anaesthetic machine should be kept free from all vapours of halogenated anaesthetics, and methods of cooling should be planned. A prompt availability in all operating theatres of dantrolene and the required machines is emphasized. Treatment of a MH episode includes stopping the administration of triggering agents, administering dantrolene, correcting metabolic and respiratory acidosis, and cooling. Different aspects of the cardiovascular pharmacology of dantrolene are discussed. Other drugs are seldom required if proper treatment is started soon enough after the crisis. Complications may arise during a fulminant episode. They are difficult to treat, and may lead to sequelae. A rational approach to the treatment of hyperkalaemia, circulatory and renal failure is discussed. After the crisis, dantrolene should be continued for a short time. Finally, the nonspecific signs which can give the earliest diagnosis possible of MH are discussed: an early diagnosis and early treatment with dantrolene are essential in reducing the mortality of malignant hyperthermia.

Anesthesia, General↗
PubMed1989

[Comparison of nalbuphine and pentazocine in the treatment of postoperative pain by self-administration].

The side-effects of two opioid agonist-antagonists, nalbuphine and pentazocine, were assessed when used for patient-controlled postoperative analgesia. Forty ASA I or II patients scheduled for upper abdominal surgery were randomly allocated to two equal groups. The anaesthetic technique was the same for all the patients: premedication with atropine and diazepam, induction with thiopentone and suxamethonium and maintenance with fentanyl, pancuronium, nitrous oxide and halothane. Patient-controlled computer assisted analgesia (On-Demand Analgesia Computer) was started in the recovery room at least 2 h after the last administration of fentanyl. The parameters used were: a routine hourly dose (the half of that received during the previous hour), with on demand delivery of nalbuphine (15 micrograms.kg-1) or pentazocine (45 micrograms.kg-1) aliquots respectively, with a refractory period between two demands of 4 min and a total hourly maximum dose of 16 mg and 48 mg respectively. The following parameters were measured before the start of self-administration, and every hour afterwards for 24 h: systolic (Pasys) and diastolic blood pressures, heart rate, pressure-rate product (PRP), respiratory rate, end-tidal CO2 and pain (by way of a three point scale). Analgesia was assessed on a four-point scale every 6 h. The total doses of nalbuphine and pentazocine administered were 94 +/- 43 mg and 251 +/- 150 mg respectively. The only parameters significantly different between the two groups were Pasys and PRP, being higher in the pentazocine group. There were no significant differences in the side-effects (drowsiness, nausea, vomiting, headache, amnesia, logorrhoea and urine retention). All patients in both groups were satisfied with this technique.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1988

[Registration of peranesthetic cases of malignant hyperthermia in France. An update].

Sixty-two suspected crises of anaesthetic malignant hyperthermia (MH) were collected between 1969 and 1988 by a retrospective inquiry which lasted four years. 33 patients (53%) died whilst 29 survived. 20 cases were confirmed to be MH, either directly or indirectly by way of muscle biopsy and halothane and caffeine contracture tests carried out according to the European MH group protocol by two laboratories. This group included 11 of the deaths, one family member of whom, at least, is sensitive (MHS), 7 MHS survivors and 2 survivors too young to undergo muscle biopsy but belonging to MHS families. 21 cases were highly suspect of MH: 15 of the deaths which occurred in a typical way, and 6 patients of three different families who have suffered from anaesthetic deaths which, clinically, suggested MH. Another 15 were possible MH cases, all survivors, including one case of Steinert's disease and a brother of a case of central core disease. 2 cases were still being debated, because they had equivocal results for the caffeine test (MHEc); the last 4 had negative muscle biopsies and were excluded. 33 close relatives of the MH patients were diagnosed as MHS. 44 others were found to be free from the genetic predisposition. It was strongly recommended to yet 11 others that they carry the MHS card because they were MHEc. The clinical, surgical and anesthetic pictures were always as described in the literature. The anaesthetic protocols included inhalational agents in 90% of cases; these were combined with suxamethonium in 55% of cases. Dantrolene was only used in 32% of cases, and then at inadequate doses and very often too late; this probably explains the large number of treatment failures. The number of severe forms of MH was also very high in this series (70%). The need to increase the means of prevention and screening for MH in France is stressed.

Adolescent↗
PubMed1988

Complications related to anaesthesia in infants and children. A prospective survey of 40240 anaesthetics.

A prospective survey of anaesthesia-related mortality and morbidity in infants and children was carried out in a representative sample of anaesthetics performed in 440 institutions chosen at random in France. A total of 40240 anaesthetics were administered to patients younger than 15 yr, 2103 (5%) involving infants (younger than 1 yr). Twenty-seven major complications related to anaesthesia occurred during or within 24 h of the anaesthesia--an incidence of 0.7 per 1000 anaesthetics. Nine, of which four were associated with cardiac arrest, were observed in infants, whereas in children there were 18 complications of which eight were associated with cardiac arrest, one with fatal outcome. The risk of complications was significantly higher (P less than 0.001) in infants (4.3 per 1000) than in children (0.5 per 1000). Accidents observed in infants mainly occurred during maintenance of anaesthesia and were the result of respiratory failure. In children, circulatory failure was as frequent as respiratory failure and complications were observed almost equally during induction and maintenance and on recovery. The rate of complications increased significantly with the ASA score and the number of co-existing diseases. The incidence was also higher when a previous history of anaesthesia was present, when the procedure was an emergency, and when the duration of preoperative fasting was less than 8 h.

Adolescent↗
PubMed1987

[Capnography].

Explore the source record for details and available documents.

Anesthesia↗
PubMed1987

The effects of halothane on the human beta-adrenergic receptor of lymphocyte membranes.

The effects of halothane on beta-adrenergic receptor antagonist interaction were studied using the membranes of human lymphocytes as a model. Membrane preparations of lymphocytes were obtained from blood samples withdrawn from seven healthy young volunteers. Beta-receptor studies were performed using (-)125I iodocyanopindolol (125ICP) binding. Non-specific binding was determined in the presence of (-)isoproterenol. Beta-receptor density (Bmax) and the dissociation constant (KD) for 125ICP were determined from saturation curves. Beta-receptor affinity for agonists evaluated by the IC50 (the concentration of isoproterenol required to inhibit 50% of specific 125ICP binding) and the dissociation constant (KL) for isoproterenol was established from competition curves. The effect of halothane 1%, in an air oxygen mixture (oxygen fraction: 0.3) administered by tonometry during ligand membrane incubation, on beta-adrenergic receptor, was compared to that of control experiments not exposed to halothane. Halothane produced a moderate but significant decrease of Bmax (-10%) and a significant increase in non-specific binding (+30%), while KD, IC50, and KL were unchanged. The authors conclude that halothane, in vitro, decreases beta-adrenergic receptor density. This effect could be mediated by an alteration of the receptor in the membrane due to action of halothane on the lipid phase of the membrane.

Adult↗
PubMed1987

Different effects of halothane on diaphragm and hindlimb muscle in rats.

The effects of halothane administration on diaphragm and tibialis anterior (TA) muscle were investigated in 30 anesthetized mechanically ventilated rats. Diaphragmatic strength was assessed in 17 rats by measuring the abdominal pressure (Pab) generated during supramaximal stimulation of the intramuscular phrenic nerve endings at frequencies of 0.5, 30, and 100 Hz. Halothane was administered during 30 min at a constant minimum alveolar concentration (MAC): 0.5, 1, and 1.5 MAC in three groups of five rats. For each MAC, Pab was significantly reduced for all frequencies of stimulation except at 100 Hz during 0.5 MAC halothane exposure. The effects of halothane (0.5, 1, and 1.5 MAC) on diaphragmatic neuromuscular transmission were assessed in five other rats by measuring the integrated electrical activity of the diaphragm (Edi) during electrical stimulation of the phrenic nerve. No change in Edi was observed during halothane exposure. In five other rats TA contraction was studied by measuring the strength of isometric contraction of the muscle during electrical stimulation of its nerve supply at different frequencies (0.5, 30, and 100 Hz). Muscle function was unchanged during administration of halothane in a cumulative fashion from 0.5 to 1.5 MAC. These results demonstrate that halothane does not affect hindlimb muscle function, whereas it had a direct negative inotropic effect on rat diaphragmatic muscle.

Animals↗
PubMed1979

Halothane biotransformation in anesthetists.

Serum bromide levels were measured in 115 anesthetists by use of x-ray fluorescence spectrometry. Bromide levels peaked at 184 +/- 21 micron in anesthetists regularly exposed to halothane (n = 20), at 58 +/- 4 micron in anesthetists sporadically exposed to halothane (n = 71), and at 46 +/- 3 micron in nonexposed anesthetists (n = 24). Kinetic studies were carried out in five other anesthetists after ten days of exposure to halothane. Average daily halothane concentration was 19.2 +/- 3.2 ppm; duration of exposure was 3.8 +/- 0.2 hours/day. Mean serum bromide level increased from 40 +/- 4 micron before exposure to 220 +/- 36 micron on the last day of exposure. Serum bromide half-life was 14 +/- 1.7 days. The study demonstrates that anesthetists debrominate halothane in a dose-related fashion. Serum bromide levels achieved, however, were far below those reported to result in clinical bromism.

Anesthesiology↗
PubMedDate not supplied

Can the extent of halothane debromination be predicted preoperatively?

In an attempt to predict the extent of halothane debromination, antipyrine metabolic clearance rate was measured preoperatively in 22 surgical patients, then correlated with percent hours of subsequent halothane exposure and postoperative serum bromide levels. There was a significant correlation (r = 0.78, p less than 0.001) between peak bromide level and anesthetic exposure but no correlation between peak bromide levels and antipyrine metabolic clearance rate. Thus, antipyrine is of no value for predicting the extent of halothane debromination. Mean peak bromide level 0.97 +/- 0.09 mM occurred on day 3 after anesthesia. This value is well below the psychoactive range. The data, therefore, also suggest that there is not a causal relationship between halothane biotransformation and the clinical syndrome of bromism.

Adult↗
PubMedDate not supplied

[Pediatric anesthesia in France. Which patients? What reasons?].

The population undergoing anaesthesia and the reasons for such a procedure were studied in children (under 15 years of age), through data collected in an INSERM national survey on anaesthesia. This survey was representative of the whole anaesthetic activity performed yearly in France. 750,000 anaesthesias are performed each year in paediatrics, giving an annual rate of 6.4 anaesthesias per 100 children. The highest rate was observed at the age of 4 years, and the higher percentage of boys exists at any age. The main fields of intervention are ENT surgery (30.9%), digestive surgery (25.2%), orthopedic and trauma surgery (12,2%) and surgery on male genitalia (8.9%). The most common procedure is appendectomy which accounts for one fifth of all procedures in children (153,000 each year).

Adolescent↗