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H Deriaz

Publications and source records attributed to H Deriaz.

At least 19 recordsLinked to original sources
PubMed2000

Haemodynamic stability during moderate hypotensive anaesthesia for spinal surgery. A comparison between desflurane and isoflurane.

BACKGROUND: The aim of this study was to compare desflurane and isoflurane for spinal procedures requiring moderate levels of controlled arterial hypotension, when these agents were administered via a semi-closed circuit at 1 l x min(-1) fresh gas flow. METHODS: After ethics committee approval and written informed consent, 20 ASA I or II patients were randomly allocated to receive either desflurane (n=10) or isoflurane (n=10), in O2/ N2O (1:1) for maintenance of anaesthesia. Induction of anaesthesia, fentanyl dosing and volume loading were standardized. Blood pressure was invasively monitored and maintained within a target systolic blood pressure (SBP) range of 80 to 100 mmHg during the study period. Results were presented as medians and interquartiles, and non-parametric statistical methods were used. RESULTS: Patient demographic data, SBP and heart rate prior to surgery, and duration of the procedure were similar between the two groups. During the study period, tighter arterial blood pressure control was maintained with desflurane as compared with isoflurane. SBP was 21.2% (9.5-41.7) of time outside the range 80-100 mmHg with isoflurane and 5.1% (0.6-10.3) with desflurane (P<0.01). CONCLUSIONS: Desflurane, administered via a semi-closed circuit at 1 l x min(-1) fresh gas flow, maintained better haemodynamic stability in spinal surgery requiring moderate arterial hypotension than isoflurane.

Adolescent↗
PubMed1998

Comparative effects of desflurane and isoflurane on recovery after long lasting anaesthesia.

PURPOSE: Increasing the duration of exposure could lead to amplification of the pharmacokinetic differences between halogenated anaesthetic agents. The aim of our study was to compare anaesthesia recovery after desflurane and isoflurane, administered for more than three hours. METHODS: After informed consent, patients were randomly assigned to either desflurane (n = 15) or isoflurane (n = 15) groups. At the end of surgery, halogenated agents were discontinued and fresh gas flow was increased to 6 l.min-1 oxygen 100%. RESULTS: Mean anaesthesia duration was 292 +/- 63 and 304 +/- 91 min in the desflurane and isoflurane groups respectively. After desflurane and isoflurane discontinuation, the time to opening eyes was 12 +/- 7 and 24 +/- 11 min respectively (P < 0.001); to squeeze fingers at command was 17 +/- 11 and 35 +/- 19 min (P < 0.001); to extubation was 16 +/- 6 and 33 +/- 13 min (P < 0.001); to give their name was 22 +/- 12 and 43 +/- 21 min (P < 0.001); to achieve a Steward score of 6 was 28 +/- 16 and 57 +/- 33 min (P < 0.001), to be fit for discharge from the recovery room was 46 +/- 19 and 81 +/- 37 min (P < 0.003). Ranges of times to reappearance of recovery variables in the desflurane group were less than those after isoflurane (P < 0.05). CONCLUSION: After long duration anaesthesia lasting up to three hours, desflurane allowed recovery and extubation in approximately half the time required by isoflurane. Less variability in results suggests better predictability of recovery with desflurane.

Adolescent↗
PubMed1998

Duration of the pharmacodynamic interaction between pancuronium and mivacurium.

The aim of this study was to determine for how long the duration of action of increments of mivacurium can be influenced by previous pancuronium administration. Fifteen patients, ASA I or II, undergoing general anaesthesia for major abdominal surgery were investigated. The post-tetanic count (PTC) was measured at the adductor pollicis muscle. Pancuronium 0.1 mg kg-1 was injected first. At recovery of the 10th response of the PTC (PTC10), a second dose of pancuronium was injected (0.02 mg kg-1). On recovery to PTC10, a bolus of mivacurium (0.04 mg kg-1) was given and regularly repeated at recovery of PTC10 until the end of surgery. The mean duration of the second dose of pancuronium was 53 min (SD 13 min) and of the first dose of mivacurium, 66 min (SD 14 min) (P < 0.01). The duration of action of further mivacurium boluses decreased significantly until the fifth dose. It took 222 minutes (95% confidence interval 190, 253 min) after the second pancuronium dose before the duration of action of mivacurium returned to normal values and became constant and predictable.

Abdomen↗
PubMed1997

[Desflurane and errors of gas selection on vaporizer analyzer].

With monochromatic infrared gas spectrometers (MIS), the displayed concentration is computed from measured IR absorption and a gain factor specific for the selected volatile agent (VA). As MIS cannot detect which VA is actually present, the displayed concentration can be very different from the actual one. As bottles and vaporizers are very specific for desflurane, it is impossible to misfill a vaporizer; however an erroneous selection of VA on MIS remains possible. The aim of this study was to assess the displayed concentrations after erroneous vapour selection on the monitor. When either desflurane, or isoflurane or enflurane were delivered at constant concentrations, all VA measured by the MIS, namely desflurane, sevoflurane, isoflurane, enflurane and halothane were successively selected and the displayed concentrations compared with the actual vapour concentration using a Capnomac Ultima (Datex) monitor. Consequences of erroneous selection can be included in three categories: 1) dangerous error, when a displayed concentration is much lower than the actual one, e.g. desflurane or sevoflurane erroneously selected; 2) evident error, when displayed concentration is much higher than 10 vol%; 3) uncomfortable situation, when displayed and actual concentrations are similar, e.g. isoflurane erroneously selected instead of desflurane. This error can only be detected by a careful checking of the device.

Anesthetics, Inhalation↗
PubMed1997

Inhalation anesthesia. What to learn from modelisation?

Models describing pharmacokinetics of inhalational anesthetic agents have been developed, usually on Mapleson's description of the body as a collection of tissues characterised by their volume, local blood flow and anesthetic solubility. Such models are very useful to understand the use of inhalation agents and circle circuit, to compare consumption of different agents in different anesthetic practices, and to prepare the anesthetist to administer new products safely.

Anesthetics, Inhalation↗
PubMed1994

[Dysfunction of vaporizers and nitrous oxide: solubility or viscosity?].

Sudden switch of carrier gas from O2 to the N2O/O2 mixture results in an acute decrease in vapour output for a variable delay of time. This has been attributed to the dissolution of N2O in the volatile anaesthetic liquid. The final vapour concentration at steady state had been previously reported to be lower than the concentration dial setting: this was attributed to vaporizer design and to viscosity of carrier gas. When N2O/O2 flow is replaced by O2, the reverse changes occur. To test whether solubility or viscosity is the main factor of the acute changes in vaporizer output when changing the carrier gas, two experiments have been designed. Two types of vaporizers, Cyprane Mark 3 and Dräger Vapor 19, were used to deliver either halothane, or enflurane, or isoflurane. The delivered concentrations were measured in triplicate with an infrared analyzer, zero corrected for N2O, Datex Capnomac and recorded on a Gould polygraph. The analyzer was calibrated before each measure. All measures were obtained at the same dial setting and the same gas flow. To test the solubility hypothesis, the same enflurane Dräger Vapor 19 vaporizer was emptied, dried, saturated with enflurane, emptied and then filled with either 10 or 100 mL of liquid enflurane. To test the viscosity hypothesis, a model of a vaporizer was devised, in which the gas movements are described with the Poiseuille's law. In this model, the delivered concentration F depends on the vapour pressure, the input pressure of the gas flow, the viscosity of the carrier gas and the viscosity of the agent saturated gas.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1992

[Effect of hygrophobic filter or heated humidifier on peroperative hypothermia].

A study was carried out to find out whether the use of a hygrophobic filter (Pall, Ultipor) or of a heated humidifier (Dräger, Aquapor) during surgery had any effect on a patient's intraoperative core temperature and thermal balance. Seventy-five ASA I or II patients scheduled for gynaecological surgery were randomly assigned to three groups: group A (n = 25), where no warming device was used; and two groups (n = 25 for each) where inhaled gases were humidified and heated with either a hygrophobic filter set up between the endotracheal tube and the Y-piece (group B) or a heated humidifier set to 100% saturation at a temperature of 41.5 degrees C (group C). The patients were all anaesthetised with the same technique (thiopentone 5 mg.kg-1, dextromoramide 0.03 mg.kg-1 and 0.1 mg.kg-1 of either pancuronium or vecuronium, followed by enflurane with nitrous oxide in oxygen); the perfused fluids were not heated. Room, tympanic, rectal, oesophageal and four skin (thorax, arm, leg, thigh) temperatures were measured with calibrated Exacon thermistances, on arrival in the operating theatre, during induction, every ten minutes for two hours, and then every twenty minutes for two hours more. Ramanathan's and Burton's formulae were used to calculate mean skin temperature and heat loss respectively. In the recovery room, patients were warmed up with an electric blanket. Shivering was ranked from "0" to "+ +". There were no differences between groups as far as age, drug doses, perfusion volumes and room temperature were concerned.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1992

[Monochromatic infrared halogenated gas analyzer and handling errors].

Monochromatic infrared gas spectrometers cannot identify volatile agents. Such an analyser (Capnomac, Datex) was tested while performing two errors: a) erroneous selection of the agent on the analyser, the vaporizer being filled with the correct agent; b) total or partial filling of the vaporizer (Vapor 19, Dräger) with an incorrect agent, the analyser being set for the agent the vaporizer was specified for. Three agents were studied, halothane (H), enflurane (E) and isoflurane (I). Each experiment was made in triplicate, the vaporizer being dried out between each. In case of erroneous selection on the analyser, differences between E and I were very small. When H was erroneously selected, the concentration displayed was six times higher, and when E or I was selected instead of H, the concentration displayed was six times lower than expected. In the 3.3-3.5 m band, H transmittance was six times higher than those of E and I. The agent selection control changes the gain so as to correct for the selected agent (gain for H: 12.0, E: 2.24, I: 1.89). In case of erroneous filling of the vaporizer, the concentration displayed was always different from that expected. When E or I was delivered with an H vaporizer, the analyser being set on H, the concentration displayed was 3 to 9 times higher than the concentration that had been set. On the other hand, when H was delivered with an E or I vaporizer, the analyser being set to E or I, the concentration displayed was 4 to 8 times lower.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1992

[Physical modeling of inhalation anesthesia].

A new physical model simulating the pharmacokinetics of volatile anaesthetics is presented. It consists in a ventilator connected to a water manometer. Gas is removed from the gaseous part of this manometer with a constant rate pump. This gas flow is directed thereafter into three capacitances with valves and pumps: one capacitance only contains air, representing the lungs, and the other two olive oil, representing the visceral and muscle compartments. Halothane, enflurane and isoflurane (1 vol%) were administered to this model with different values of cardiac output and alveolar ventilation. There was good concordance between the values of FA/FI that were measured in this model and those calculated by computer simulation. No correction factor was required. Such a physical model may therefore be used to test new techniques of administration of volatile agents.

Anesthesia, Inhalation↗
PubMed1992

[Effects of nifedipine premedication on peroperative hypothermia].

The intraoperative time-course of core temperature in patients premedicated with nifedipine (n = 30) was compared to that of control patients (n = 30). Distal oesophageal temperature (TCORE) was recorded every five minutes during total hip replacement in 60 adults ranked ASA 1 to 2. Patients in the control group were only premedicated with 100 mg of oral hydroxyzine. The treatment group consisted of 30 patients taking nifedipine for blood pressure control or coronary insufficiency. They were given 10 mg sublingual nifedipine as well as the hydroxyzine premedication. Anaesthesia was induced with thiopentone, fentanyl and vecuronium, and maintained with nitrous oxide in oxygen and halothane in a semi-closed circuit. The slopes of the time-course for TCORE were established for each patient, using two linear regressions, between 0 and 0.5 h and from 1 to 2 h. The two groups did not differ in age, weight, ambient temperature, blood pressure, heart rate, and volume of unwarmed blood transfused. TCORE differed significantly from the 25th minute on until the end of the study period. Contrary to all expectation the TCORE at 2 h was higher in the nifedipine group (34.85 +/- 0.09 degrees C) than in the control group (34.01 +/- 0.14 degrees C, p < 0.001). TCORE decreased more rapidly in the control group during the first study interval (0 to 0.5 h), -1.50 +/- 0.60 degrees C.h-1 vs -2.34 +/- 1.02 degrees C.h-1 (p < 0.001). The second slopes did not differ particularly (-0.96 +/- 1.32 degrees C.h-1 vs -0.90 +/- 0.42 degrees C.h-1 respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

[Postoperative shivering: analysis of main associated factors].

This study was carried out in 75 female patients, ranked ASA 1 or 2, during recovery from balanced general anaesthesia. It aimed to find out the main determinants of postoperative shivering and its thermal effects. Skin and oesophageal temperature were recorded every ten minutes. Mean skin and body temperatures, and the intraoperative energy balance were calculated. There was no additional source of heating. Shivering was ranked from 0 to 2. Statistical analysis showed that the starting mean core and body temperatures were the only factors correlated with shivering and its intensity, whereas mean skin temperatures, age and opioid doses were not. Between 33.5 and 36.5 degrees C, there was a linear relationship between the oesophageal temperature at the end of anaesthesia and the incidence of shivering. A decrease of 1 degrees C in core temperature increased the probability of shivering by 33%. At 35.4 degrees C, 50% of patients shivered. There was a homogenous group of patients whose oesophageal temperature at the end of anaesthesia was between 35 and 36 degrees C. In this group, there was no significant difference between starting skin temperatures, whether the patient shivered or not. However, the core temperature of those within that group that did shiver returned to normal levels more quickly than in those that did not shiver. These data underlined the essential role played by core temperature at the end of anaesthesia in postoperative shivering and its intensity, as well as the heat producing value of shivering. It would therefore seem logical to prevent postoperative shivering by avoiding intraoperative hypothermia.

Adult↗
PubMed1989

[A mistake in the filling of a vaporizer detected by an infrared analyser of halogenated anesthetic agents].

An anaesthetic pitfall related to an incorrectly filled vaporizer, without harmful effects on the patient, is reported. A halothane specific vaporizer has been accidentally partially filled with enflurane. The incident was suspected when the Datex Normac infrared analyser, calibrated for halothane, displayed an inspired concentration of 0.83% v/v, whereas the Dräger Vapor 19 vaporizer dial was set to deliver 0.4% v/v with a fresh gas flow of 2.7 l.min-1 to a circle system. The analyser uses infrared gas spectrometry, in the 3.3 to 3.5 microns band which contains the absorption peaks of halothane, enflurane, isoflurane and methoxyflurane. The four agents have different transmittances, with halothane the greatest. The agent selection control changes the gain to correct for the selected agent. The measurements are only accurate when only one agent is present at a time. In the reported case, the displayed concentration was very high because the high gain of halothane (12.0) was applied to enflurane (enflurane gain: 2.24). An in vitro experiment measuring the values of different enflurane/halothane mixtures, carried out with the involved vaporizer, showed that it contained, at the time of the incident, a mixture of 20% enflurane and 80% halothane. It may therefore be possible to detect a vaporizer filling error when the values "measured" by the analyser are not in concordance with those set on the vaporizer. Filling an enflurane vaporizer with halothane is more dangerous, as it results in a high halothane output with a Normac "enflurane" inspired concentration remaining very low. The indexed pin safety system remains the best means of avoiding wrong vaporizer filling.

Anesthesia, General↗
PubMed1989

Vascular occlusions for liver resections. Operative management and tolerance to hepatic ischemia: 142 cases.

The intra- and early postoperative courses of 142 consecutive patients who underwent liver resections using vascular occlusions to reduce bleeding were reviewed. In 127 patients, the remnant liver parenchyma was normal, and 15 patients had liver cirrhosis. Eighty-five patients underwent major liver resections: right, extended right, or left lobectomies. Portal triad clamping (PTC) was used alone in 107 cases. Complete hepatic vascular exclusion (HVE) combining PTC and occlusion of the inferior vena cava below and above the liver was used for 35 major liver resections. These 35 patients had large or posterior liver tumors, and HVE was used to reduce the risks of massive bleeding or air embolism caused by an accidental tear of the vena cava or a hepatic vein. Duration of normothermic liver ischemia was 32.3 +/- 1.2 minutes (mean +/- SEM) and ranged from 8 to 90 minutes. Amount of blood transfusion was 5.5 +/- 0.5 (mean +/- SEM) units of packed red blood cells. There were eight operative deaths (5.6%). Overall, postoperative complications occurred in 46 patients (32%). The patients who experienced complications after surgery had received more blood transfusion than those with an uneventful postoperative course (p less than 0.001). The length of postoperative hospital stay was also correlated with the amount of blood transfused during surgery (p less than 0.001). On the other hand, there was no correlation between the durations of liver ischemia of up to 90 minutes and the lengths of postoperative hospital stay. The longest periods of ischemia were not associated with increased rates of postoperative complications, liver failures, or deaths. There was no difference in mortality or morbidity after major liver resections performed with the use of HVE as compared with major liver resections carried out with PTC alone, although the lesions were larger in the former group. It is concluded that the main priority during liver resections is to reduce operative bleeding. Vascular occlusions aim at achieving this goal and can be extended safely for up to 60 minutes.

Aged↗