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Biomedical subjects

V Piat

Publications and source records attributed to V Piat.

6 recordsLinked to original sources
PubMed1999

Changes in electroencephalogram and autonomic cardiovascular activity during induction of anesthesia with sevoflurane compared with halothane in children.

BACKGROUND: This study was design to assess clinical agitation, electroencephalogram (EEG) and autonomic cardiovascular activity changes in children during induction of anesthesia with sevoflurane compared with halothane using noninvasive recording of EEG, heart rate, and finger blood pressure. METHODS: Children aged 2-12 yr premedicated with midazolam were randomly assigned to one of three induction techniques: 7% sevoflurane in 100% O2 (group SevoRAPID); 2%, 4%, 6%, and 7% sevoflurane in 100% O2 (group SevoINCR); or 1%, 2%, 3%, and 3.5% halothane in 50% N2O-50% O2 (group HaloN2O). An additional group of children who received 7% sevoflurane in 50% N2O-50% O2 (group SevoN2O) was enrolled after completion of the study. Induction was videotaped. EEG, heart rate, and finger blood pressure were continuously recorded during induction until 5 min after tracheal intubation and analyzed in frequency domain using spectral analysis. RESULTS: Agitation was more frequent when anesthesia was induced with 100% O2 compared to the mixture of oxygen and nitrous oxide. No seizures were recorded in any group. In the four groups, induction of anesthesia was associated with an increase in EEG total spectral power and a shift toward the low-frequency bands. Sharp slow waves were present on EEG tracings of the three sevoflurane groups, whereas slow waves and fast rhythms (spindles) were observed in the halothane group. Sevoflurane induced a greater withdrawal of parasympathetic activity than halothane and a transient relative increase in sympathetic vascular tone at loss of eyelash reflex. CONCLUSIONS: Agitation observed during sevoflurane induction was not associated with seizures. Sevoflurane induction induced a marked inhibition of parasympathetic control of heart rate.

Anesthesia, Inhalation↗
PubMed1999

Comparison of three techniques for induction of anaesthesia with sevoflurane in children.

This study was designed to evaluate the clinical characteristics of three induction techniques using sevoflurane in children scheduled for tonsillectomy: incremental induction with sevoflurane(2,4,6,7%) in 100% O2 (group IC-O2; n=23); induction with high concentration of sevoflurane in 100% O2 (group HC-O2; n=22); and induction with high concentration of sevoflurane in a mixture of O2:N2O(50:50) (group HC-N2O; n=20). Induction was well accepted and well tolerated in most children. The addition of nitrous oxide resulted in faster loss of consciousness (P< 0.001) compared to the other induction techniques and in a tendency for reduced excitement compared with the same rapid technique without nitrous oxide (P=0.053). Time to tracheal intubation was identical in the three groups and intubation conditions were scored as good in most children. During the early induction phase, an increase in SAP and HR was observed in the three groups. Changes were maximal at two min after the beginning of induction in the three groups. SAP and HR values were back to baseline values at the time of tracheal intubation. In conclusion, the addition of nitrous oxide to a high sevoflurane concentration decreases the time to loss of eyelash reflex, tends to reduce the incidence of excitement and is not associated with an increased incidence of respiratory complications even in patients with obstructive airway.

Analysis of Variance↗
PubMed1995

[Sevoflurane].

Sevoflurane, a methylethylether halogenated solely with fluorine, is characterized by a low blood/gas solubility (blood/gas partition coefficient = 0.65). This feature allows in a more rapid uptake and elimination than with more soluble agents. MAC is about 2 vol% in young adults and 2.5 vol% in children of more than 6 months of age. It undergoes degradation by soda lime in various components. Among them, compound A (an olefin) produces renal toxicity in rats. Total sevoflurane metabolism represents about 5% of inhaled dose and produces inorganic fluorides. However no renal toxic effects has been reported up to now in animals and in patients. The effects on central nervous and cardiovascular systems are close to those of isoflurane. It decreases cerebral vascular resistances and cerebral oxygen consumption, but does not cause convulsive activity. It decreases myocardial contractility, systolic arterial pressure and systemic vascular resistances, but heart rate remains basically unchanged up to 1 MAC. It does not sensitize the myocardium to catecholamines. It depresses ventilation in a dose-dependent fashion, this effect being more pronounced than that of halothane but less than that of both isoflurane and enflurane. It is not irritant for the airways and has some bronchodilatory effect. In adults, recovery is more rapid than with isoflurane. In children, sevoflurane seems a promising agent owing to its good acceptance for mask induction, as well as its favourable haemodynamic profile. However due to its rapid elimination, analgesic drugs should be administered early enough to decrease the incidence of postoperative pain.

Adolescent↗
PubMed1994

Induction and recovery characteristics and hemodynamic responses to sevoflurane and halothane in children.

The present study was designed to compare induction and recovery characteristics of sevoflurane and halothane anesthesia in children, and to assess the hemodynamic profile of both anesthetics during induction and maintenance of anesthesia. Thirty-four children (aged 9 mo-9 yr) scheduled for ambulatory surgery were allocated randomly to groups to receive either halothane (HALO, n = 17) or sevoflurane (SEVO, n = 17) in a mixture of O2 and N2O (40:60) for mask induction and maintenance of anesthesia. The inspired concentrations used for inhalation via a mask were increased every five breaths and were successively 1%, 2%, 3%, and 3.5% for HALO and 2%, 4%, 6%, and 7% for SEVO. After tracheal intubation, expired concentration was maintained at 1 minimum alveolar anesthetic concentration (MAC) corrected for age until skin closure. Analgesia was provided by epidural anesthesia using a mixture of plain 1% lidocaine and 0.25% bupivacaine. Induction and recovery characteristics as well as hemodynamic data were recorded. The two groups were identical in age, weight, and duration of anesthesia and surgery. Time to intubation was the same between groups. In the SEVO group, five children exhibited mild excitement, while in the HALO group, one mild laryngospasm and one transient cardiovascular deterioration were observed. In the SEVO group, a significant increase in heart rate (HR) was observed before tracheal intubation, but during maintenance of anesthesia HR and systolic arterial pressure (SAP) did not change compared to control values. In the HALO group, HR did not change throughout the study, whereas SAP remained significantly below control values throughout both induction and maintenance of anesthesia.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗
PubMed1993

[Anesthesia in the management of pyloric stenosis. Evaluation of the combination of propofol-halogenated anesthetics].

This study was aimed at evaluating haemodynamic changes during an anaesthetic sequence for full stomach, using propofol as induction agent and volatile anaesthetics for maintenance of anaesthesia in infants scheduled for surgical cure of hypertrophic pyloric stenosis. After correction of preoperative blood electrolyte and metabolic disturbances with appropriate i.v. hydrating solutions, anaesthesia was induced with propofol and suxamethonium. Infants were divided in two groups according to the volatile anaesthetic agent used for maintenance of anaesthesia after tracheal intubation: halothane (n = 16) or isoflurane (n = 15). The two groups were identical regarding weight (4.28 +/- 0.6 vs 4.14 +/- 0.76 kg), age (1.6 +/- 0.9 vs 1.5 +/- 0.6 months), preinduction heart rate (155 +/- 22 vs 151 +/- 22 b.min-1) and systolic-diastolic arterial pressure (96 +/- 18/58 +/- 12 vs 105 +/- 16/67 +/- 15 mmHg). Propofol and suxamethonium doses were identical, 3.9 +/- 1 mg.kg-1 and 1.3 +/- 0.6 mg.kg-1 respectively in halothane group, vs 4.3 +/- 0.8 mg.kg-1 and 1.3 +/- 0.4 mg.kg-1 in isoflurane group. Heart rate did not change after induction of anaesthesia, while arterial blood pressure decreased significantly (p < 0.001). However, blood pressure remained within the normal range for age throughout the procedure. Mean duration of surgery was shorter in halothane group (64 +/- 16 vs 79 +/- 17 min, p < 0.05), however time-interval from the end of surgery to tracheal extubation (12 +/- 6 vs 15 +/- 8 min) was short and identical in the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, General↗