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Biomedical subjects

J H Gaudy

Publications and source records attributed to J H Gaudy.

At least 19 recordsLinked to original sources
PubMed1992

[The measurement of pH and gases in the blood using microanalysis: the effect of storage at 4 degrees C for an hour. A study in the rat].

The effects of one hour storage at 4 degrees C on micro blood gas samples (150 microliters) were studied for a wide range of values (pH: 7.11-7.58; PCO2: 26-97 mmHg; PO2: 31-503 mmHg) in 20 rats with indwelling carotid artery catheters. Blood gas values were modified by varying the composition of inspired gases: normoxia, hypocapnic hypoxia, hyperoxia, hypercapnia (in this case eight animals were anaesthetized with halothane 1.1%). One hundred and eight double micro-samples were taken. For each double sample, one was analysed immediately (H0) and compared with the second sample after one hr storage at 4 degrees C (H1). The Bland and Altman method was used for the statistical analysis of results. After one hr storage at 4 degrees C, the PCO2 was slightly higher than at H0 (mean difference +/- SD: +1.08 +/- 1.7 mmHg) and arterial pH was slightly lower (mean difference +/- SD: -0.016 upH +/- 0.011 upH). These results show that for these two variables, in the range studied, one hour storage at 4 degrees C had little effect. In contrast, for arterial PO2 the mean difference between all measurements between H1 and H0 was -17 +/- 25 mmHg. If results lower than 200 mmHg (56 double samples) are considered separately, the mean difference between values at H1 and H0 was only -0.98 +/- 5.3 mmHg. For PaO2 greater than 200 mmHg (52 double samples), the mean difference was -34 +/- 26.3 mmHg; this may be due to low reproducibility of measurements of elevated PO2 levels and to the effects of cellular metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia, Inhalation↗
PubMed1992

[Respiratory effects of moderate hypothermia (36 degrees C-28 degrees C) in dogs under halothane anesthesia].

Changes in systemic haemodynamic variables (mean arterial pressure, MAP; heart rate, HR; cardiac output, Qc), in oxygen consumption, VO2, and in ventilation (minute ventilation, V; respiratory frequency, f; tidal volume, VT; and arterial blood gases) with particular attention to respiratory times (duration of inspiration, TI; duration of expiration, TE; duration of the breathing cycle, TTOT), to respiratory timing (TI/TTOT) and respiratory drive (VT/TI) were studied during moderate progressive hypothermia (36 degrees C to 28 degrees C) during stable halothane anaesthesia (MAC = 1.5) in six dogs. MAP, HR and Qc decreased; V and f decreased, the decrease in f being correlated with that in temperature (r = 0.66; P < 0.01). Tidal volume did not change. The PaO2 and pHa decreased while PaCO2 increased slightly. The decrease in ventilation was related to changes in respiratory times (TI and TE) which increased (TE more than TI) and in respiratory drive (VT/TI which decreased due to the increase in TI). The relation between VT/TI and TI/TTOT changes was not constant during cooling. Changes in respiratory times and drive could be due to the effect of cold on medullar respiratory control.

Anesthesia, Inhalation↗
PubMed1990

[Respiratory effects of almitrine on various levels of the fraction of inspired oxygen. A study in the anesthetized dog].

The effects of intravenous almitrine under normoxic, hyperoxic, and hypoxic conditions were studied in 5 male beagle dogs (mean weight 15.2 +/- 5 kg) anaesthetized with thiopentone. Plasma concentrations of thiopentone were maintained constant at 27-29 mg.1(-1). Each animal underwent twice the three different experiments, with a lapse of a fortnight between each experiment: a) breathing room air, with intravenous administration of 1 mg.kg-1 almitrine over 30 s, b) breathing room air, then pure oxygen for 15 min, followed by an intravenous administration of 1 mg.kg-1 almitrine over 30 s with the dog still breathing pure oxygen, and c) breathing room air, then progressively less oxygen (FIO2 0.18, 0.16, 0.14, 0.12 for 5 min each), followed by an intravenous administration of 1 mg.kg-1 almitrine over 30 s with the dog still breathing a mixture with 12% oxygen. Tidal volume, respiratory rate, minute ventilation, inspiratory and expiratory duration, arterial pH, PaO2 and PaCO2 were measured respectively in room air, after 100% oxygen, in hypoxia (FIO2 = 0.12), before, 5 and 10 min after the injection of almitrine. Hyperoxia depressed ventilation (-21%), whilst hypoxia stimulated it (+126%), although significantly less than in the awake animal. Almitrine restored the respiratory response to hypoxia, but hyperoxia did not suppress respiratory stimulation due to the drug. It would therefore seem likely that almitrine acts on peripheral arterial chemoreceptors, but also on other structures. The results of this study suggest that almitrine may be useful in restoring the respiratory response to hypoxia during recovery from anaesthesia.

Almitrine↗
PubMed1990

Ventilatory effects of almitrine bismesilate in dogs breathing normoxic, hyperoxic and hypoxic mixtures.

The ventilatory effects of 1 mg.kg-1 i.v. almitrine were studied in five dogs anaesthetized with halothane 2% under conditions of normoxia, hyperoxia and hypoxia. Ventilation (minute ventilation, respiratory frequency, tidal volume, duration of inspiration and expiration, ratio TI/Ttot and VT/TI), Pao2, Paco2, pHa, systemic arterial pressure and heart rate were measured in air before and following almitrine; in air, after inhalation of pure oxygen and after almitrine in hyperoxia; in air, during hypoxia with Fio2 progressively decreased from 0.21 to 0.12 and after almitrine in hypoxia (FIO2 = 0.12). Halothane decreased ventilatory response to hypoxia. Almitrine stimulated ventilation irrespective of the level of oxygenation and restored the ventilatory response to hypoxia. Hyperoxia did not suppress ventilatory action of almitrine whose action is probably partly central. Hypoxia and almitrine did not induce major systemic haemodynamic modification.

Almitrine↗
PubMed1989

Effects of ketamine on isolated human bronchial preparations.

The bronchodilator effects of ketamine were examined in human bronchial preparations contracted maximally with histamine, acetylcholine, barium chloride or potassium chloride. Antagonism between ketamine and either histamine or acetylcholine was examined also. Ketamine caused bronchial relaxation irrespective of the constricting agent, and exerted a partial and non-competitive antagonism to histamine and acetylcholine. Propranolol and indomethacin did not inhibit the effect of ketamine, excluding the involvement of beta activation and of prostaglandins.

Acetylcholine↗
PubMed1988

Ventilatory effects of oxygen in the dog under thiopentone anaesthesia.

The ventilatory effects of prolonged oxygen administration were examined in seven dogs during thiopentone anaesthesia. Ventilation, tidal volume (VT), ventilatory rate (f), minute ventilation (VE), inspiratory time (TI), expiratory time (TE), period (Ttot), TI/Ttot and mean inspiratory flow (VT/TI) were measured during the inhalation of room air, after 30 min of oxygen inhalation, and finally after a return to breathing room air. Arterial blood-gas tensions were measured before and after 5, 10, 20 and 30 min of oxygen administration and 15 min after return to breathing room air. Oxygen administration produced an immediate, significant and persistent decrease in ventilation, principally from a decrease in ventilatory rate and changes in ventilatory times. This was in contrast to what occurred in awake animals. Modifications in ventilatory mechanics or suppression of an hypoxic stimulus to ventilation were probably not involved. Anaesthesia may modify centrally mediated ventilatory responses to hyperoxia.

Anesthesia, Intravenous↗
PubMed1987

[Evaluation of a protocol for selective ordering of preoperative tests in healthy subjects].

A protocol for selective ordering of 12 preoperative tests was prospectively evaluated during one year in a teaching hospital. 1600 consecutive healthy patients had an average of 2.4 tests each, but 270 of them had none. Usefulness of tests was assessed by taking into account not simply their abnormality yield, but also their impact on patient care during the whole hospital stay in the anaesthetist view. The possible value of tests omitted was assessed by anaesthetists at the end of hospital stay. As a consequence of test results, surgery was delayed in one patient, and a treatment was started or the anaesthetic management adapted in 16.7% of tests performed (279/3905) were found to be useful and 0.1% of tests not carried out (21/15295) would have been potentially useful. No complication inducing sequelae or death could be linked to tests not carried out. This study showed that routine preoperative investigations in healthy patients could be avoided without any adverse effects on patient care.

Adult↗
PubMed1987

Effects of increasing enflurane concentrations on intraocular pressure.

The effects of enflurane at various concentrations on intraocular pressure (IOP) were studied. In 15 healthy patients, intubated and mechanically ventilated, IOP was measured the day before surgery, after premedication and during anaesthesia, after administration of 0.5%, 1.0% or 1.5% enflurane. Enflurane in combination with general anaesthesia and controlled ventilation (PCO2 4.7-5.3 kPa) caused a significant decrease in IOP. The decrease was more marked (44%) with 1% enflurane than with 0.5% enflurane (21%). The change in IOP was comparable with 1.0% and 1.5% enflurane; however, systolic arterial pressure decreased more with enflurane 1.5%. Increasing the inspired concentration of enflurane from 1% to 1.5% did not appear to be associated with any further decrease in IOP.

Adult↗
PubMed1986

Evaluation of a protocol for selective ordering of preoperative tests.

A protocol for selective ordering of 12 preoperative tests, according to clinical status and type of surgery, was prospectively tested for one year in a teaching hospital. 3866 consecutive surgical patients had an average of about 4 tests each. The possible value of tests that were omitted was assessed in the light of events during and after operation. According to predetermined criteria, 0.4% of non-ordered tests would have been potentially useful; but in the opinion of the anaesthetists, only 0.2% would actually have been useful. The protocol therefore had little adverse effect on patient care and was acceptable to clinicians.

Adult↗
PubMed1986

Ventilatory response of the conscious or anesthetized cat to oxygen breathing.

In conscious intact cats, oxygen breathing for up to 1 h does not modify ventilation, and the ventilatory response to CO2 in hyperoxia is not consistently decreased. However, oxygen breathing induces sustained hyperventilation in conscious cats after carotid body denervation. In anesthetized cats, oxygen breathing provokes a hypoventilation which is transient under light anesthesia but more sustained under deeper levels of anesthesia. At all levels of anesthesia, the ventilatory response to CO2 is decreased in hyperoxia as compared with normoxia. These results suggest that: the effects of hyperoxia include a central stimulating component, seen only in conscious animals, which offsets the decreased ventilatory drive from peripheral chemoreceptors; this central component is sensitive to anesthesia, thus allowing an explanation for the permanent decrease in ventilation and decrease in ventilatory response to CO2 observed when oxygen is given during deep anesthesia; and anesthesia may help to purposefully unmask factors involved in the control of breathing, but it markedly alters the normal functioning of the respiratory network.

Anesthesia↗
PubMed1986

Ventilatory recovery from hypothermia in anesthetized cats.

Ventilation and breathing pattern were recorded in a group of seven anesthetized cats during rewarming from 24 to 38 degrees C of esophageal temperature. It was found that at 24 degrees C, ventilation was very much depressed accounting for an alveolar hypoventilation resulting in hypoxia and hypercapnia. During rewarming, ventilation increased steadily; this was caused by sequential changes in central inspiratory activity (VT/Ti) and Ti/Tt ratio reflecting breath timing. Changes in VT/Ti have been initially attributed to an improvement in chemoresponsiveness and subsequently, to an involvement of supra-pontine thermoregulatory control areas during rewarming. Marked changes in breath timing, especially observed between 28 and 34 degrees C, have been attributed to a direct effect of rewarming upon the brain stem respiratory network. It has the result, that during hypothermia, several components of the respiratory control system are differently affected causing marked changes in breathing pattern and ventilation. They are accompanied by modifications in arterial blood pressure and heart rate.

Animals↗
PubMed1978

Changes in ventilatory pattern induced by intravenous anesthetic agents in human subjects.

The tidal volume-inspiratory duration relationship was studied during air breathing and rebreathing in conscious and anesthetized human subjects using three different intravenous agents. The results observed have been compared with similar experiments carried out in cats. Its has been shown that anesthesia provokes an increase in breathing rate associated with a decrease in tidal volume in human subjects; an opposite effect on breathing rate was observed in cats. Thus, the tidal volume-inspiratory duration relationship, although very similar in the conscious cat or human subject, is very different under anesthesia. The results were quite consistent in a given species whatever the nature of the drug used. It is suggested that modifications of the breathing rate by anesthesia, related to animal species, are caused by central effects of the drug. These effects are probably mediated by different actions on inputs to the inspiratory "off-switch" mechanisms in the two species.

Alfaxalone Alfadolone Mixture↗
PubMed1978

[Allergy to suxamethonium. Case report].

The authors describe a clinical case of an allergy to suxamethonium (succinylcholine) chloride which prompted--a posteriori--an allergological work-up. This, in turn, demonstrated all the factors favoring histamine-release: atopic predisposition, tendency of nonspecific histamine-release, and real allergy to the muscle relaxant. This study has enabled the induction of anaesthesia without any problems, by avoiding the allergens through preventive therapy.

Adult↗