The Effects of Changes of Posture and Anaesthesia on Cardiopulmonary Function in Man and Horses

Littlejohn, A.; Mitchell, B.

doi:10.1111/j.1467-2995.1972.tb00209.x

Cited by 8 publications

(5 citation statements)

References 25 publications

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“…The observations made in the animals under halothane/oxygen anaesthesia, but not subjected to expiratory resistance, were similar to those reported previously (Hall, Gillespie and Tyler, 1968;Gillespie, Tyler and Hall, 1969;de Moor and van den Hende, 1972;Littlejohn and Mitchell, 1972) and there can be little doubt that under this type of anaesthesia hypoventilation is usual. The further decrease in ventilation associated with the imposition of both 10 cm and 20 cm H 2 O resistance to expiration is clearly unwelcome.…”

Section: Discussionsupporting

confidence: 89%

“…In horses large alveolar-arterial oxygen tension differences occur during halothane/oxygen anaesthesia with either spontaneous breathing or intermittent positive pressure ventilation (Hall, Gillespie and Tyler, 1968;Gillespie, Tyler and Hall, 1969;de Moor and van den Hende, 1972;Littlejohn and Mitchell, 1972). Various observations led to the suggestion (Hall, 1971) that gas trapping consequent upon airway closure in the lowermost zones of the lungs might contribute to this large gradient.…”

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confidence: 99%

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Positive End-Expiratory Pressure in Anaesthetized Spontaneously Breathing Horses

Hall

Trim

1975

British Journal of Anaesthesia

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Horses breathing spontaneously under halothane anaesthesia were subjected to expiratory resistance by the introduction of a water-trap into the expiratory limb of a circle absorber. Resistances of 10 and 20 cm H2O produced no significant increase in PaO2 (P greater than 0.05) during halothane/air and halothane/oxygen anaesthesia. The imposition of resistance was associated with an increase in PaCO2 and a significant increase in mixed venous PCO2. In three animals subjected to 20 cm H2O resistance under halothane/air anaesthesia, the cardiac output was reduced (P less than 0.01). It was concluded that the indiscriminate application of end-expiratory pressure has no place in routine equine anaesthesia.

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Section: Discussionsupporting

confidence: 89%

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confidence: 99%

Positive End-Expiratory Pressure in Anaesthetized Spontaneously Breathing Horses

Hall

Trim

1975

British Journal of Anaesthesia

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“…It is known that large end-tidal/arterial and alveolar/ arterial oxygen tension differences exist in anaesthetised, laterally recumbent horses (Gabel, Heath, Ross, Hamlin EQUINE VETERINARY JOURNAL and Smith, 1966; Hall, Gillespie and Tyler, 1968;Littlejohn and Mitchell, 1972). The posture of lateral recumbency, in a species as large as the horse, results in a mismatching of pulmonary ventilation and perfusion, because of the effect of gravity on the pulmonary circulation and restricted ventilation of the lower lobes of the lungs.…”

Section: Discussionmentioning

confidence: 99%

Influence of the Neuroleptanalgesic Combination of Etorphine and Acepromazine on the Horse: Blood Gases and Acid‐base Balance

Hillidge

Lees

1975

Equine Veterinary Journal

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SUMMARY Respiratory function and acid‐base variables were studied in Welsh Mountain ponies before and at predetermined times after the intravenous injection of Immobilon and Revivon. A marked depression of respiratory rate was accompanied by large reductions in arterial blood oxygen tension and saturation and the development of a mild respiratory acidosis following the injection of Immobilon. It was concluded that at least three factors contributed to the hypoxic hypoxia produced by Immobilon; the posture of lateral recumbency, the decrease in respiratory rate and the laboured character of the respiration. Arterial oxygen and carbon dioxide tensions returned towards control levels soon after administering Revivon. Mixed venous oxygen tensions were little affected by either Immobilon or Revivon, and mixed venous carbon dioxide tensions were increased to smaller degrees than those of arterial blood. Haemoglobin concentration was increased initially by Immobilon, had returned to the control level by 30 min and fell below the control following the administration of Revivon. RÉSUMÉ La fonction respiratoire et les variations acide‐base furent étudiées sur des poneys Welsh Mountain, avant, puis à des moments pré‐déterminés suivant l'administration d'Immobilon et de Revivon. Une dépression marquée du rythme respiratoire accompagnée par une chute importante de la pression d'oxygène dans le sang artériel et par une acidose respiratoire modèrée furent constatés, après injection d'Immobilon. On en a conclu que trois facteurs au moins contribuent à l'hypoxie engendrée par l'Immobilon: le decubitus latéral, le ralentissement du rythme respiratoire, et le caractère pénible de la respiration. Après l'injection de Revivon le taux de l'oxygène artériel et de CO2 revinrent rapidement à la normale. La tension veineuse d'oxygène fut peu modifiée par l'Immobilon ou par le Revivon, la tension de CO2 veineuse étant accrue à un moindre degré que dans le sang artériel. L'Immobilon éleva la concentration en hémoglobine à la phase initiale, concentration revenant à la normale après 30 minutes puis diminuant après injection de Revivon. ZUSAMMENFASSUNG Die Atemfunktionen und Säure‐Basenwerte von Welshponies wurde vor und zu bestimmten Zeiten nach der intravenösen Injektion von Immobilon und Revivon untersucht. Eine deutliche Depression der Atemfrequenz wurde begleitet von einer starken Reduktion der arteriellen Sauerstoffspannung und –sättigung und von der Entwicklung einer milden respiratorischen Acidose nach der Injektion von Immobilon. Es wurde geschlossen, dass zum mindesten drei Faktoren für die Hypoxie nach Immobilongabe verantwortlich gewesen sind: die Seitenlage, der Abfall der Atemfrequenz und die angestrengte Atmung. Arterielle Sauerstoff‐ und Kohlensäurespannungen kehrten kurz nach der Verabreichung von Revivon zur Norm zurück. Gemischte venöse Sauerstoffspannungen wurden von Immobilon und Revivon wenig beeinflusst und die venöse Kohlensäurespannung erhöhte sich weniger deutlich als in arteriellem Blut. Die Haemoglobinkonzentration...

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“…1) and the lower corresponding PaCO2 in the subsequent control period [von Euler, Herrero and Wexler, 1970]. The smaller decline of PaCO2 in the sheep could be due to artefacts imposed by the experimental conditions, for example the level of anaesthesia or the position of the animals [Littlejohn and Mitchell, 1972]. The sheep were placed in the prone position and the dogs and rabbits were supine.…”

Section: Effect Of Vagotomy On Animals Breathing Airmentioning

confidence: 99%

The Effects of Vagotomy on Ventilation and Blood Gas Composition in Dog, Sheep and Rabbit

Kashani

Haigh

1975

Exp Physiol

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The influence of vagotomy on resting arterial blood gases (PaCO2 and PaO2) and on the ventilatory responses to hypercapnia and hypoxia was studied in three different species of anaesthetized animals. After bilateral cervical vagotomy resting PaCO2 generally declined. In the dog, where this was studied more fully, resting PaCO2 declined significantly (8.13+O067 mm Hg) over several hours, but PaO2 changes were not significant.After vagotomy tidal volume (VT), but not frequency (f), increased with increasing chemical drive. It is concluded that the increase in frequency in response to increased CO2 or decreased 02 is dependent on the vagal mechanisms. [1880] suggested that stimulation of the vagus was ineffective in animals made apnoeic by hyperventilation. Rice [1938] reported that hypercapnia produced by increased respiratory dead space caused a decrease in the effectiveness of the vagal reflexes while Woldring [1965] showed that the sensitivity of the inspiratory muscles to a given change in lung volume in anaesthetized cats varied with the level of arterial PaCO2.Although it is well known that the vagus nerves are the afferent pathway for a number of respiratory reflexes affecting rate and depth of breathing and there is some information on the minute volume/end tidal PaCO2 relationship after vagotomy, it is not clear what influence the vagi exert on maintenance of a normal arterial CO2 tension. The present study endeavours to establish a more quantitative relationship between the effects of vagotomy on arterial blood gas tension in the resting state as well as during hypercapnia and hypoxia in three different species. METHODSExperiments were carried out in thirteen rabbits (body weight 1-9-3-7 kg), twenty dogs (7419-2 kg) and twelve sheep (22-0-43-0 kg). Food was withheld for 12 hr before the experiment but the animals were allowed free access to water.

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The Effects of Changes of Posture and Anaesthesia on Cardiopulmonary Function in Man and Horses

Cited by 8 publications

References 25 publications

Positive End-Expiratory Pressure in Anaesthetized Spontaneously Breathing Horses

Positive End-Expiratory Pressure in Anaesthetized Spontaneously Breathing Horses

Influence of the Neuroleptanalgesic Combination of Etorphine and Acepromazine on the Horse: Blood Gases and Acid‐base Balance

The Effects of Vagotomy on Ventilation and Blood Gas Composition in Dog, Sheep and Rabbit

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