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Biomedical subjects

H Gilly

Publications and source records attributed to H Gilly.

At least 55 records · Page 3Linked to original sources
PubMed1987

Effects of midbrain stimulation and iontophoretic application of serotonin, noradrenaline, morphine and GABA on electrical thresholds of afferent C- and A-fibre terminals in cat spinal cord.

We have used the single-fibre excitability testing method to investigate whether electrical stimulation in midbrain periaqueductal gray or lateral reticular formation, as well as intraspinal iontophoretic application of the suspected inhibitory neurotransmitters serotonin (5-hydroxytryptamine), noradrenaline, the opiate morphine, or gamma-aminobutyric acid (GABA), exert presynaptic actions at the central terminals of cutaneous afferent unmyelinated or myelinated fibres. Thresholds to antidromically excited 42 single unmyelinated and 18 myelinated fibres in the sural nerve by intraspinal microstimulation were determined before and during periaqueductal gray or lateral reticular formation stimulation (3 100 ms trains/s at 100 Hz; 100-900 microA) or intraspinal iontophoretic application (40-300 nA) of 5-hydroxytryptamine, noradrenaline, morphine or GABA from a multibarrel micropipette. Periaqueductal gray or lateral reticular formation stimulation had mixed effects on unmyelinated and myelinated fibre thresholds, with most threshold measurements within +/- 10% of control. There was a tendency for thresholds to increase more during periaqueductal gray than lateral reticular formation stimulation. Thresholds of unmyelinated fibres were predominantly raised during iontophoretic application of 5-hydroxytryptamine (20/29 fibres), noradrenaline (10/13) and morphine (15/21), while GABA had mixed effects; thresholds of nearly all myelinated fibres were raised by each drug. Both periaqueductal gray or lateral reticular formation stimulation and application of 5-hydroxytryptamine, noradrenaline or morphine tended to raise thresholds in the majority of the 53 unmyelinated and myelinated fibres tested. Methodological problems in interpreting the physiological significance of these results for presynaptic modulation are discussed.

Animals↗
PubMed1986

[Differences in the neuromuscular blockade of the larynx and thenar muscles following relaxation with vecuronium].

To objectivate the clinical impression of different neuromuscular depression in the larynx- and limb-musculature, an attempt was made in 5 patients to quantify laryngeal muscle relaxation by electromyographic recordings of evoked responses from the vocalis muscle during endolaryngeal microsurgery. Mechanographic and evoked electromyographic recordings of the thenar muscles were obtained simultaneously. Nearly total suppression of evoked responses at the peripheral muscle site was observed after a bolus dose of either 60 micrograms/kg or 100 micrograms/kg of the nondepolarising muscle relaxant Vecuronium. However, the vocalis muscle was not blocked completely. The neuromuscular depression ranged from 61 to 92% depending on the dose. In no case was the recommended intubating dose (ED 95) of 60 micrograms/kg sufficient for complete relaxation of the vocalis muscle. The present results do not support that the extent and/or time course of intrinsic laryngeal muscle relaxation correlates with peripheral neuromuscular depression in a quantitative manner. The different degree of relaxation achieved by Vecuronium in the hand and larynx is probably due to their different content of acetylcholine receptors.

Adult↗
PubMed1986

[The pharmacodynamics of vecuronium on the musculature of the vocal cords and the ball of the thumb. Preliminary report].

During endolaryngeal microsurgery, an attempt was made to quantify laryngeal muscle relaxation by electromyographic recording of evoked responses from the vocal cord musculature in 5 patients. Both mechanographic and electromyographic recordings from the adductor pollicis were obtained simultaneously. Following a bolus dose of vecuronium (60 micrograms/kg, n = 3, and 100 micrograms/kg, n = 2), nearly total (97%-100%) suppression of evoked responses at the peripheral muscle site was observed; the vocal cords, however, did not show complete neuromuscular (nm) blockade, but rather varying degrees of nm depression ranging from 61%-92%. The present results clearly show that quantitative information as to duration and degree of neuromuscular depression in the vocal musculature may be obtained by electromyographic recordings of evoked potentials in the clinical setting; it is impossible however, to quantitatively estimate the extent of intrinsic laryngeal muscle relaxation from peripheral nm depression. The pharmacodynamic differences observed might be due to the varying acetylcholine receptor density of the muscle groups studied.

Adult↗
PubMed1985

[Uptake and elimination of isoflurane and halothane by children and adults].

The rate of increase of alveolar concentrations (FA/FI) of isoflurane and halothane was studied in children and adults during general anaesthesia and controlled ventilation. After 30 min of body equilibrium, elimination curves of the volatile anaesthetics were determined by measurement of alveolar (FA/FA0; infrared technique) and venous concentrations (gas chromatography). The distribution and elimination half-times (t1/2 alpha, t1/2 beta), clearance (Cl), volume of central and peripheral compartment (V1, Vz) and the volume of distribution at steady state (Vss) were calculated from the intercepts and slopes of a two-compartment model. During the uptake of anaesthetic concentrations of isoflurane and halothane, the FA/FI ratio of each gas was found to rise significantly faster in children than in adults. The reason for the more rapid approach to equilibrium in children seems to be related to physiological differences. Irrespective of age, uptake of isoflurane was more rapid than that of halothane, as it is less soluble. Similarly, isoflurane was eliminated from the lung or blood faster than halothane. Moreover, anaesthetic wash-out in children differed from that in adults. In the paediatric age group t1/2 beta under isoflurane was shorter than in adults, whereas halothane excretion took longer in children. This could be accounted for by the larger volumes of distribution Vz and Vss in the young, due to higher organ affinity of halothane. From our data we conclude that age significantly affects uptake and elimination of volatile anaesthetics and the control of anaesthesia is easiest with isoflurane in paediatric patients.

Adult↗
PubMed1985

[Evaluation of the thermal technic for the quantitative measurement of extravascular lung water].

To evaluate the accuracy of the method, sequential measurements (n = 159) of extravascular lung water (EVLW) using the thermo-dye double-indicator dilution technique were performed in 22 critically surgical ill patients. Radiographic grading of lung water content served as clinical standard. Normal mean EVLW defined radiographically without evidence of pulmonary edema was 4.8 +/- 1.1 ml/kg. Early interstitial fluid accumulation was quite accurately detected with 6.9 +/- 2.1 ml/kg EVLW (p less than 0.001 vs normal lung water content). The mean EVLW present with definitive interstitial and alveolar edema was 11.5 +/- 3.8 ml/kg and 19.1 +/- 4.5 ml/kg, respectively. Despite some objections to the method (diffusion limitation of the thermal indicator, uneven regional lung perfusion), this technique for measuring EVLW reliably assesses the degree of pulmonary edema. Even when properly performed, chest roentgenograms only confirm gross changes in the lung water content.

Adolescent↗
PubMed1985

[Local anesthetic effects of morphine and naloxone].

The effects of both morphine (Mo) and naloxone (Nal), topically applied to the desheathed saphenous nerve, were studied in Sprague-Dawley rats during 22 min of superfusion at various concentrations (Mo: 0.086, 0.28, 0.86, 2.8, 8.6 mM/l; Nal: 0.1, 0.33, 1.0 mM/l) by recording single C-fibres. C-fibres were electrically stimulated and the latencies of action potentials were measured. Both drugs impaired nerve conduction in a dose-dependent, fully reversible manner. At high concentrations, conduction was blocked in 5 of 11 (Mo 2.8 mM/l) and 3 of 8 (Nal 1 mM/l) fibres. Mo (8.6 mM/l) instantly blocked all C-fibres investigated. Subsequent washing out of the drug resulted in complete recovery. The findings indicate that Mo and Nal also show local anaesthetic properties; a non-opiate receptor-specific mechanism is postulated. In spite of their blocking action, at present neither Mo nor Nal seems to provide distinct advantages over other agents that have been used successfully to induce reversible nerve blockade at peripheral sites. Due to the rather high dosage necessary (1-2 mg/ml), well-known side-effects of these opiates must also be taken into consideration.

Action Potentials↗
PubMed1984

Vascular reactions correlated with pain due to cold.

Psychophysical experiments with healthy volunteers were conducted to study the relationships between cold pain and blood perfusion of the skin. By means of a thermode the left middle finger was cooled to a constant temperature near 0 degrees C for 45 min. During this stimulation period, the subject regularly rated the pain on an electronically controlled visual analogue scale. Two variables of vascular reactions were measured: the finger photoplethysmogram of the cooled finger and the thermal flux at the skin surface of this finger. Cross correlograms computed between these noninvasive physiologic parameters of blood flow and the pain ratings revealed that pain intensity and degree of vasoconstriction were strongly correlated. The implications of these findings for the peripheral nociceptor mechanism of cold pain are discussed. We conclude that the nociceptors for this type of pain are most probably situated in deeper skin structures and that they are excited by temperatures ranging approximately from 3 to 20 degrees C.

Adult↗
PubMed1983

Comparative investigations on the cardiovascular effects of Org NC45 and pancuronium in dogs.

Cardiovascular effects of Org NC 45 and pancuronium were examined in seven anaesthetized dogs. Systemic circulatory effects were measured after increasing doses administered as a single i.v. bolus. Cardiac effects were measured after intracoronary (i.c.) injection of the equivalent dose of the respective neuromuscular blocking agent, which produced 90% neuromuscular blockade. Org NC 45 i.v. did not cause any significant cardiovascular changes, whereas pancuronium i.v. produced significant and dose-related increases in heart rate, left ventricular (LV) dP/dtmax and cardiac output (CO). After i.c. injection of equipotent doses, neither drug induced any significant change in haemodynamic measurements. This implies that neither drug exerted a direct influence on cardiac contractility, the increases in LV dP/dt max and CO following pancuronium being dependent on heart rate.

Animals↗
PubMed1983

Importance of myocardial loading conditions in determining the effects of enflurane on left ventricular function in the intact and isolated canine heart.

The effect of enflurane (2% and 4% inspired) on left ventricular (LV) function were examined in chronically instrumented dogs, both intact and after isolation of their hearts and lungs from the systemic circulation. Enflurane in the intact dogs increased heart rate (32 +/- 5% with 2% and 41 +/- 4% with 4%) and elicited striking, dose-dependent decreases in LV stroke shortening (-30 +/- 3% and -41 +/- 4%), the maximum velocity of LV fiber shortening, dD/dt, (-23 +/- 2%) and -40 +/- 2%), LV systolic pressure (-25 +/- 3% and -33 +/- 2%), the maximum rise of LV-pressure, dP/dt (-33 +/- 5% and -55 +/- 3%), and mean aortic pressure (-27 +/- 2% and -37 +/- 1%). However, the LV diastolic performance was impaired little, i.e., even with the higher concentration the LV end-diastolic pressure rose only moderately (32 +/- 4%), while the LV end-diastolic dimensions failed to change significantly; both LV end-diastolic pressure and LV end-diastolic diameter were decreased with the low concentration. Enflurane, after beta-adrenergic blockade alone or after combined beta-adrenergic and cholinergic blockades, or with spontaneous ventilation instead of controlled ventilation, had similar effects. By contrast, in the hearts that were isolated from the systemic circulation and the complex neurohumoral environment, enflurane increased both LV end-diastolic pressure (116 +/- 32% and 492 +/- 58%) and LV end-diastolic diameter (13 +/- 3% and 28 +/- 7%). In intact dogs with aortic pressure artificially increased to conscious control levels, enflurane likewise caused a distinct depression of the LV diastolic performance. Thus, LV systolic unloading appears to be mandatory in order to prevent acute myocardial failure from higher doses of enflurane. The observed changes in LV function with enflurane are largely independent of cardiac rate, adrenergic and cholinergic influences, and the hemodynamic consequences of intermittent positive-pressure ventilation.

Animals↗
PubMed1982

[A thermodynamic model to predict oxygen consumption and peripheral blood flow in the newborn infant. II. Its validity under steady-state conditions].

A thermodynamic model, which allows to predict oxygen consumption and peripheral blood flow from temperature measurements, was tested for its validity in newborn infants. This model is based on the close relation between 1) oxygen consumption and heat production and 2) between circulation and heat convection. In this model 3 temperatures on the patient, 2 temperatures in the environment and geometrical variables (weight, length) are measured and known physiological relations used to calculate oxygen consumption (VO2) and peripheral blood flow (pBF). In 15 newborns the VO2 was synchroneously determined by means of the flow-trough method and the thermomodel. The VO2 and the VO2/kg bodyweight respectively correlated significantly (p less than 0.01) with the directly measured VO2 (correlation coefficients r 0.89 and 0.66 respectively). In 12 newborns the peripheral blood flow was synchroneously determined by means of the impedance plethysmography and the thermomodel. The directly measured peripheral blood flow correlated significantly (p less than 0.001) with the peripheral heat flow (r = 0.73, 34 measurements) and with the peripheral blood flow (r = 0.86, 34 measurements) both obtained from the thermomodel. The values of VO2 and pBF obtained by direct measurement and by the thermomodel are as closely correlated as values which were obtained comparing two conventional methods. These results demonstrate the validity of the theoretical model being suitable for clinical use to continuously predict VO2 and pBF.

Humans↗
PubMed1981

Endorphins: mechanism of acupuncture analgesia.

Discharges were recorded from spinal dorsal horn neurons in response to noxious skin heating (50 degrees C) in anesthetized cats. Repetitive electrical stimulation of the superficial peroneal (SP) and posterior tibial (PT) nerves inhibited these nociceptive discharges as well as systemic administration of met-enkephalinamide (synthetic endorphin). The inhibitory effects of electro-stimulation as well as administration of synthetic endorphin were partially but significantly antagonized by naloxone, thus arguing in favor of endogenous morphine release as the basis for the mechanism of acupuncture analgesia. However, non-responding neuronal units to the administration of enkephalin were also observed in the present study. These non-responding units may explain why acupuncture is not effective in some individuals.

Acupuncture Therapy↗
PubMed1981

[Haemodynamic changes during intracoronary infusion of norepinephrine. A study of the halothane-induced circulatory depression (author's transl)].

The haemodynamic effects of halothane (0.9 vol% = 1 MAC) and of intracoronary infusion of norepinephrine (14.28 +/- 3.28 ng/kg/min) were investigated in anesthetized dogs (n=6). During inhalation of halothane the left ventricular (LV) stroke volume was diminished while heart rate and total peripheral resistance exhibited no significant changes. In spite of this cardiodepressive action, by means of a decrease in both LV-end-diastolic pressure and LV-end-diastolic volume, a backward heart failure could be excluded. Intracoronary infusion of norepinephrine increased the contractility of the left ventricle leading to an increase in LV-dP/dtmax to control values. However, in comparison to the original level, cardiac output and mean arterial blood pressure remained decreased. Thus, selective inotropic stimulation failed to antagonize the halothane-induced circulatory depression. In a second series of experiments performed on chronically instrumented dogs (n=5) the haemodynamic effects of piritramide (0.3 mg/kg/h i.v.), i.e. the anaesthetic used for preparation of the animals in the acute experiments, were studied during anaesthesia with halothane (1 MAC). While dipidolor failed to elicit significant changes under these conditions, haemodynamic side effects cannot generally be excluded since there is evidence that narcotic analgesics interfere with the neural control of the cardiovascular system.

Anesthesia↗
PubMed1981

[Clinical monitoring of colloid osmotic pressure; a comparison of the performance of two oncometers].

The increasing importance of repeated measurements of colloid osmotic pressure, particularly in intensive care units and and anaesthesiology, is briefly outlined. The results of comparative measurements with two commercially available oncometers (Knauer Membran-Osmometer No. 1 and IL-186 Weil Oncometer No.2) are reviewed. In-vitro testing of the two apparatus with a 6.7 per cent albumin solution produced practically identical results. Measurements in the sera of patients after haemodilution differed slightly, the values being lower with No.2. Although this oncometer is faster and easier to operate certain draw-backs (related to calibration etc.) at present preclude its routine use by the untrained clinician.

Humans↗
PubMed1980

[Cardiovascular effects of two synthetic enkephalin analogues following intracoronary administration in dogs (author's transl)].

Haemodynamic changes following intracoronary injection of two synthetic Met5-enkephalin analogues (FK 33-824 and DALA) with prolonged action as compared with "natural" enkephalines were investigated in anaesthetized dogs (n = 5; dosage; 200, 400, 600 micrograms of both substances i. cor.). DALA led to a shortlasting (5 minutes) rise in heart rate associated with an increase in cardiac output and left ventricular dp/dt max. Besides, a fall in mean arterial blood pressure was noted. No alterations in the pulmonary circulation were encountered. FK 33-824 elicited similar, but unpronounced changes. Direct influences on baroreceptor activity or endogenous release of vasoactive substances as the cause of circulatory effects occuring primarily under DALA were discussed. It is concluded that the cardiovascular effects of synthetic opioids resemble those of morphine and its related compounds.

Animals↗
PubMed1979

[Functional evaluation of "tekatest", a test equipment for halothane-vaporizers (author's transl)].

The results of investigations on the reliability of a commericially available test equipment for anaesthetic vaporizers based on the Rotameter principle (s.c. "Tekatest") are reported. In prototype devices scattered differences up to 27% between the results obtained by the Tekatest and those derived from gas chromatography and mass-spectrometry were noted; in a somewhat improved version an unidirectional error of about 24% became evident. Up to now, therefore, this test equipment cannot be recommended for recalibration of vaporizers in clinical use.

Anesthesia, General↗