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Biomedical subjects

H Gilly

Publications and source records attributed to H Gilly.

At least 37 records · Page 2Linked to original sources

Classification of malignant hyperthermia-equivocal patients by 4-chloro-M-cresol.

To clarify the contracture response to 4-chloro-m-cresol (4-CmC) in malignant hyperthermia (MH) equivocal (MHE) muscle, we studied the effect of cumulative concentrations of 4-CmC. In vitro contracture test (IVCT) was performed in 35 probands according to the European MH test protocol. Surplus muscle bundles were exposed to 4-CmC (25-200 micromol/L), maintaining each concentration for 4 and 8 min. After 4 min exposure, the contracture increase of MH susceptible (MHS) (n = 7) muscle specimens was significantly (P = 0.05) greater at 50 micromol/L compared with either MHE halothane sensitive (MHEh) (n = 13) or MH normal (MHN) (n = 15) classified patients. Statistically significant differences (P < 0.05) were also found at 75 micromol/L. Exposure for 8 min yielded significant differences at 50 micromol/L only between MHS and MHEh. MHEh muscles revealed a dose-response curve similar to that found in MHN specimens. MHS muscles showed a significantly higher sensitivity to 4-CmC than either MHEh or MHN, and, in the probands tested so far, MHEh and MHN muscles seem to identically respond to 4-CmC, which seems to indicate a normal response in MHEh probands, implying no MH susceptibility. Therefore, 4-CmC might reduce the frequency of MHEh diagnosis based on standard halothane-caffeine IVCT. However, since MHE individuals may also represent an aberrant genetic status, with MH causing defects linked to unknown mutations, it is premature to consider 4-CmC as a solution to the diagnostic uncertainty of the true status of MHE probands. Presently, 4-CmC may provide supplementary information for a more precise phenotypic categorization of MHE individuals.

Adolescent↗

Effects of cisatracurium on cerebral and cardiovascular hemodynamics in patients with severe brain injury.

BACKGROUND: For neuroanesthesia and neurocritical care the use of drugs that do not increase or preferentially decrease intracranial pressure (ICP) or change cerebral perfusion pressure (CPP) and cerebral blood flow (CBF) are preferred. The current study investigates the effects of a single rapid bolus dose of cisatracurium on cerebral blood flow velocity, ICP, CPP, mean arterial pressure (MAP) and heart rate (HR) in 24 mechanically ventilated patients with intracranial hypertension after severe brain trauma (Glasgow coma scale <6) under continuous sedation with sufentanil and midazolam. METHODS: Patients were randomly assigned to receive either 2xED95 (n=12) or 4xED95 (n=12) of cisatracurium as a rapid i.v. bolus injection. Before and after bolus administration mean cerebral blood flow velocity (BFV, cm/s) was measured in the middle cerebral artery using a 2-MHz transcranial Doppler sonography system, ICP (mm Hg) was measured using an extradural probe, and MAP (mm Hg) and HR (b/min) were measured during a study period of 20 min. Cerebral perfusion pressure (CPP=MAP-ICP) was also calculated. RESULTS: Our data show that a single bolus dose of up to 4xED95 cisatracurium caused no significant (P<0.05) changes in BFV, ICP, CPP, MAP and HR. Possible histamine-related events were not observed during the study. CONCLUSIONS: The results from this study suggest that cisatracurium is a safe neuromuscular blocking agent for use in adult severe brain-injured patients with increased ICP under mild hyperventilation and continuous sedation.

Adult↗

Determination of mivacurium in plasma by high-performance liquid chromatography.

An assay has been developed and validated for the routine monitoring of mivacurium in plasma. It consists of liquid-liquid extraction with dichloromethane and high-performance liquid chromatography with fluorometric detection (excitation and emission wavelengths 220 nm and 320 nm, respectively). A Spherisorb C, 5 microns column and a mobile phase containing acetonitrile, KH2PO4 and methanol are used. At a flow-rate of 1 ml/min, a concentration gradient is applied. The detection limit is approximately 1 ng/ml in plasma. For the separation of steroisomeres, the Spherisorb SCX 10 microns column and acetonitrile-Na2SO4 as a mobile phase can be used. The assay shows good linearity over the range 1-1000 ng/ml. The accuracy and precision allows the utilisation in clinical pharmacokinetic studies.

Chromatography, High Pressure Liquid↗

Rescuer's work capacity and duration of cardiopulmonary resuscitation.

Specific training in the techniques of cardiopulmonary resuscitation (CPR) has been the major aim of CPR education for both health care professionals and lay people over the past few decades. We performed a randomized trial to evaluate individual physiological parameters of 12 professional rescuers influencing duration and quality of standard CPR and active compression-decompression CPR. CPR duration was assessed according to individual work capacity after grouping rescuers as untrained and trained individuals, according to their work capacity of up to and including 100% and over 100%. The average work capacity of all the rescuers was determined by incremental exercise testing, resulting in 110.0 +/- 26.5% compared with data for the normal population. With 29.3 +/- 12.8 min duration, standard CPR was significantly longer than active compression-decompression CPR with 15.5 +/- 10.2 min duration (P = 0.009). No changes in the forces of compression and decompression were measured during active compression-decompression CPR, thus demonstrating maintenance of constant CPR quality. Duration of resuscitation was influenced by the CPR method performed and by the individual work capacity (P = 0.004 and P = 0.027, respectively). We conclude that the duration of CPR depends both on the method applied and the rescuers' individual work capacity and recommend improvement of work capacity by aerobic training especially for professional rescuers.

Adult↗

Effects of rocuronium and vecuronium on intracranial pressure, mean arterial pressure and heart rate in neurosurgical patients.

We have evaluated the effects of a single bolus dose of rocuronium 0.6 mg kg-1 (group 1, n = 10) or vecuronium 0.1 mg kg-1 (group 2, n = 10) on intracranial pressure (ICP), mean arterial pressure (MAP), cerebral perfusion pressure (CPP) and heart rate (HR) in 20 neurosurgical patients undergoing mechanical ventilation of the lungs during continuous sedation with sufentanil and midazolam. Before and after neuromuscular block using twice the ED90 of the blockers, ICP, MAP, CPP and HR were recorded continuously for 15 min. Treatment caused no significant changes in ICP, CPP or MAP and there was no evidence of histamine release. Mean maximum block in the rocuronium group was slightly less than that in the vecuronium group (95.9 (3.1)% vs 100%; ns) The difference between the two groups in onset time (rocuronium 142 (62) s, vecuronium 192 (64) s; P = 0.04) was significant. Patients in the rocuronium group showed a slight (7(4)%) but significant (P = 0.003) increase in heart rate.

Adult↗

Compression characteristics of CPR manikins.

We evaluated the force-depth compression characteristics of 8 different CPR manikins during mechanical cardiopulmonary resuscitation by a thumper. The force required to compress the manikin's thorax of 1, 2, 3, 4 and 5 cm was measured. It ranged between 6.3 and 14 kp at a depth of 1 cm, 11.6-30 kp at 2 cm, 17-38 kp at 3 cm, 22.5-54 kp at 4 cm and 28.5-69 kp at 5 cm. The manikins with a spring in the thorax (Ambu Man, Ambu MultiMan, Dräger CPR-Max, Laerdal Resusci Anne) as well as one without (Ambu CPR Pal) showed a rather linear relationship between depth and force required to compress the chest. Ambu Man, set at 'High', Laerdal Resusci Anne and Dräger CPR-Max revealed a slight increase in resistance, whereas 2 manikins without a spring (Laerdal Little Anne, Laerdal Family Trainer) and 1 manikin with a plastic spring-like construction (Actar 911) exhibited less resistance with increasing depth. According to our results, the manikins are not uniform in their compression characteristics; some become nonlinear when 3 cm of compression is exceeded. For correct CPR it is of utmost importance that the CPR trainee learns to compress in a sufficiently strong manner, but simultaneously to avoid an exceedingly high depth of compression irrespective of the thorax resistance. In order to prepare the CPR student for the varying chest resistances of the human body, we recommend to train CPR on manikins with different chest resistances.

Cardiopulmonary Resuscitation↗

Pharmacodynamics, pharmacokinetics, and intubation conditions after priming with three different doses of vecuronium.

The effects of three different priming doses of vecuronium on pharmacokinetics, pharmacodynamics, and endotracheal intubation conditions were investigated. Forty-two patients were studied in two parts. In each part, 21 patients were allocated into three groups (n = 7/group) receiving 10, 15, or 20 micrograms/kg vecuronium as a priming dose, followed by a 50- micrograms/kg intubating dose 6 min later. In Part I, Train-of-Four (TOF) ratios and serum concentrations after priming were measured every minute up to the sixth minute. Onset time [from injection of the intubating dose to maximum depression of the first twitch (T1)], clinical duration (T1 return from maximum block to 25% of control), and recovery index (T1 recovery from 25% to 75% of control) were calculated and serum concentrations were determined up to 6 h after injection of the intubating dose. In Part II, the intubating dose was injected 4 min after priming, onset time was determined, and intubation conditions were scored. TOF ratio was significantly lower after priming with 20 micrograms/kg at the fifth and sixth minutes (0.59 +/- 0.29 and 0.56 +/- 0.32; mean +/- 1 SD) compared with the first minute (0.95 +/- 0.1). Recovery index was significantly increased after priming with 20 micrograms/kg (13.2 +/- 6.6 min, P < 0.05) compared with 10 micrograms/kg (9.2 +/- 4.8 min) and 15 micrograms/kg (6.7 +/- 1.5 min). Between groups no differences in onset time, clinical duration, and pharmacokinetic variables were found. In Part II, onset time and intubating scores showed no significant differences between the groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗

Effects of nimodipine on regional blood flow in heart and brain during cardiopulmonary resuscitation in pigs.

The effect of nimodipine on organ blood flow during cardiopulmonary resuscitation (CPR) was studied in 26 anesthetized pigs. After 5 min of ventricular fibrillation circulatory arrest and 5 min of external CPR, all animals received 50 micrograms/kg of epinephrine and either nimodipine (10 micrograms/kg, followed by 1 microgram.kg-1.min-1 until termination of the experiment) or placebo. Organ blood flow was measured using radioactive-labeled microspheres. The rate of resuscitability in nimodipine-treated pigs (11 of 12) was significantly higher (P < 0.05) than in placebo-treated animals (7 of 14). In pigs receiving epinephrine and nimodipine, left ventricular blood flow after restoration of spontaneous circulation (ROSC) was approximately twice as high as in pigs receiving epinephrine and placebo (P < 0.01). In nimodipine-treated pigs, total cerebral blood flow 10 min after ROSC was significantly higher than baseline values (P < 0.01) and in hypophysis, cerebellum, and medulla the blood flows were significantly higher than in placebo-treated pigs (P < 0.05). We conclude that, in our pig model, high doses of nimodipine given during CPR caused significant enhancements in left ventricular blood flow and significantly improved the rate of resuscitation.

Animals↗

Porcine model for studying the passage of non-depolarizing neuromuscular blockers through the blood-brain barrier.

A method has been developed for blood-brain barrier disruption to provide reproducible access to the cerebrospinal fluid of the cerebello-medullary cistern. The technique was used successfully to investigate transfer of pancuronium to the cerebral CSF compartment in pigs. After osmotic disruption of the blood-brain barrier, pancuronium concentrations increased significantly in the cerebrospinal fluid.

Animals↗

Anaesthetic uptake and washout characteristics of patient circuit tubing with special regard to current decontamination techniques.

The amounts of halothane and isoflurane trapped after exposure for up to 3 h at 2 MAC in commonly used anaesthesia circuit tubing were quantitated by gas chromatography. The decontaminating effects of procedures such as flushing with oxygen, thermal disinfection and/or routine storage were assessed in a similar way. After halothane exposure, anaesthetic content was highest in silicone (398 +/- 55 mg 100 g-1). Lower quantities were found in all other tubings investigated (electrically conductive latex: 64 +/- 4, conductive rubber: 62 +/- 4, polyethylene-vinyl-acetate (PEVA): 293 +/- 10 and 149 +/- 17 for non-conductive corrugated and spiral tubes, respectively, polysulfone (Hytrel): 155 +/- 10 mg 100 g-1). The isoflurane contents were substantially lower (silicone: 278 +/- 23; others: 55 +/- 7, 61 +/- 6, 163 +/- 9 and 86 +/- 8, 74 +/- 4 mg 100 g-1). The tubings' content did not correlate with the material's partition coefficient as full saturation was not achieved during exposure. Decontamination procedures reduced the content of volatile anaesthetics to a variable extent. Conductive latex and rubber showed the highest residual content, even after thermal disinfection and subsequent storage. Twenty-minute flushing with oxygen (8 l min-1) decreased effluent gas concentrations below 5 p.p.m. in all tubings. With silicone, after 1 h flushing, halothane concentrations still exceeded 10 p.p.m. (isoflurane: 8 p.p.m.). It is concluded that urgent decontamination by a 20-min flush warrants the safe re-use of previously 'contaminated' conductive rubber and latex as well as polysulfone tubings in critical situations, e.g. in malignant hyperthermia patients if disposable tubing is not immediately available.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗

[Anesthetic gas contamination in the operating room--an unsolved problem? Results of our own studies].

Ambient air concentrations of nitrous oxide (N2O) and volatile anesthetics were assessed under routine conditions in a total of 41 surgical suites located at seven Vienna hospitals. Continuous measurements were performed by means of infrared trace gas analyzers throughout a period of approximately 450 h. Additional analyses of ventilation facilities (if installed) revealed no essential deficiencies; however, anesthetic gas scavenging (AGS) systems yielded insufficient flow rates in 32% (less than 25 l/min). In surgical suites without mechanical ventilation or scavenging systems (2 out of 41), maximum occupational threshold limits (i.e., 100 ppm N2O; 5 ppm halothane) were exceeded continuously and to considerable degrees throughout the duration of anesthesia. During measurements conducted in operating rooms (ORs) in otolaryngology departments, extreme peaks (greater than 2600 ppm N2O, greater than 150 ppm halothane) of several minutes duration were documented when open-circuit anesthesia was performed. In the general surgical ORs equipped with modern ventilation facilities ambient air contamination was lowest, time-weighted average (TWA) values ranging from 8 to 15 ppm (mean 11 +/- 3 ppm) for N2O and 0.1 to 0.6 ppm (mean 0.3 +/- 0.2 ppm) for the halogenated anesthetic. Despite good ventilation and scavenging in the gynecological ORs, distinctly higher concentrations (mean 83 +/- 49, range 24-211 ppm N2O; mean 0.75 +/- 0.3, range 0.3 to 1.3 ppm volatile agent) were measured in cases where anesthesia was delivered by mask. TWA values exceeding currently established maximum workplace concentrations were found in an unscavenged but ventilated urological OR. At present, short-term concentration peaks seem to be inevitable even under optimal OR ventilation conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Air Pollution, Indoor↗