Stimulation of ventilation by normobaric hyperoxia in exercising dogs

Haouzi, P.; Allioui, E. M.; Gille, J. P.; Bedez, Y.; Tousseul, B.; Chalon, B.

doi:10.1017/s0958067000020352

Cited by 3 publications

(3 citation statements)

References 20 publications

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“…Interestingly, the apnoeic group had significantly and substantially higher PaO 2 and lower P(A‐a)O 2 at the termination of anaesthesia, than non‐apnoeic animals. Hyperoxic inhibition of ventilation has been reported experimentally in mice , rats , cats , dogs and humans and has been attributed to obtunding or eliminating carotid body chemoreceptor sensitivity to CO 2 . The relative contributions of central and peripheral chemoreceptors to respiratory drive is unclear and differences in experimental methodologies and species studied can produce conflicting results .…”

Section: Discussionmentioning

confidence: 99%

Restoration of arterial oxygen tension in horses recovering from general anaesthesia

Bardell

Mosing

Cripps

2019

Equine Veterinary Journal

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Summary Background Arterial hypoxaemia is common in anaesthetised horses, but little information exists regarding restoration of arterial oxygen tension (PaO2) during recovery from anaesthesia, or if intra‐operative management factors exert any longer‐term effect. Objectives To evaluate PaO2 in horses recovering from general anaesthesia up to 1 h after resuming standing. Study design Prospective observational clinical cohort study. Methods Systemically healthy adult horses undergoing inhalational general anaesthesia for elective surgical procedures were studied. Arterial blood samples were obtained anaerobically prior to pre‐anaesthetic medication, at end of anaesthesia, immediately following positioning in the recovery box, then at 10‐min intervals until standing. Additionally, samples were taken when horses achieved sternal recumbency, at standing (STAND) and 1 h after standing (STAND+1). Data were analysed using ANOVA and mixed‐effects linear regression, with significance set at P<0.05. Results Data from one hundred and two horses were analysed. Forty horses received controlled mandatory ventilation (CMV) throughout anaesthesia, 47 breathed spontaneously (SV) and 15 initially breathed spontaneously before CMV was imposed (S‐CMV). Overall, PaO2, P(A‐a)O2 and PaCO2 remained significantly lower than baseline at STAND+1 (P<0.01). CMV resulted in higher PaO2 at the end of anaesthesia (P = 0.03) and during early recovery (P<0.01) than SV. Only in group S‐CMV did PaO2, P(A‐a)O2 and PaCO2 return to baseline values at STAND+1. Highest PaO2 values associated with CMV were also associated with early recovery apnoea. Main limitations Non‐standardised anaesthetic management, temporal and quantitative variation in oxygen delivery during early recovery and lack of control group where oxygen was electively withheld during recovery. Conclusions Controlled mandatory ventilation results in better pulmonary function in horses as assessed by PaO2, P(A‐a)O2 and PaCO2, an effect enhanced by an initial period of SV and still evident 1 h after standing. High PaO2 values may contribute to early recovery apnoea but this does not adversely affect outcome. The Summary is available in Portuguese – see Supporting Information

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Section: Discussionmentioning

confidence: 99%

Restoration of arterial oxygen tension in horses recovering from general anaesthesia

Bardell

Mosing

Cripps

2019

Equine Veterinary Journal

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“…The complicated effect of prolonged hyperoxia was shown by Haouzi et al as during exercise in dogs the transient O 2 test increased PETCO 2 nearly 3 mmHG while prolonged hyperoxia only increased PETCO 2 0.5 mmHG (152). These authors proposed that "changes in CO 2 stores in the exercising muscles could contribute to O 2 -induced stimulation during exercise, possibly through stimulation of muscle afferents responding to local circulatory changes" (152).…”

Section: Carotid Afferent Mediation Of the Exercise Hyperpneamentioning

confidence: 99%

Control of Breathing During Exercise

Forster

Haouzi

Dempsey

2012

Comprehensive Physiology

198

203

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During exercise by healthy mammals, alveolar ventilation and alveolar-capillary diffusion increase in proportion to the increase in metabolic rate to prevent PaCO2 from increasing and PaO2 from decreasing. There is no known mechanism capable of directly sensing the rate of gas exchange in the muscles or the lungs; thus, for over a century there has been intense interest in elucidating how respiratory neurons adjust their output to variables which can not be directly monitored. Several hypotheses have been tested and supportive data were obtained, but for each hypothesis, there are contradictory data or reasons to question the validity of each hypothesis. Herein, we report a critique of the major hypotheses which has led to the following conclusions. First, a single stimulus or combination of stimuli that convincingly and entirely explains the hyperpnea has not been identified. Second, the coupling of the hyperpnea to metabolic rate is not causal but is due to of these variables each resulting from a common factor which link the circulatory and ventilatory responses to exercise. Third, stimuli postulated to act at pulmonary or cardiac receptors or carotid and intracranial chemoreceptors are not primary mediators of the hyperpnea. Fourth, stimuli originating in exercising limbs and conveyed to the brain by spinal afferents contribute to the exercise hyperpnea. Fifth, the hyperventilation during heavy exercise is not primarily due to lactacidosis stimulation of carotid chemoreceptors. Finally, since volitional exercise requires activation of the CNS, neural feed-forward (central command) mediation of the exercise hyperpnea seems intuitive and is supported by data from several studies. However, there is no compelling evidence to accept this concept as an indisputable fact.

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“…The mask was adjusted and attached to two different points behind the occipital bone and the vertex using several elastic straps. A rubber band was applied at the proximal part of the mask to prevent leakage as already reported (Haouzi et al 2000).…”

Section: Methodsmentioning

confidence: 99%

The control of ventilation is dissociated from locomotion during walking in sheep

Haouzi

Chenuel

Chalon

2004

The Journal of Physiology

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This study was designed to test the hypothesis that the frequency response of the systems controlling the motor activity of breathing and walking in quadrupeds is compatible with the idea that supra-spinal locomotor centres could proportionally drive locomotion and ventilation. The locomotor and the breath-by-breath ventilatory and gas exchange (CO 2 output (V CO 2 ) and O 2 uptake (V O 2 )) responses were studied in five sheep spontaneously walking on a treadmill. The speed of the treadmill was changed in a sinusoidal pattern of various periods (from 10 to 1 minute) and in a step-like manner. The frequency and amplitude of the limb movements, oscillating at the same period as the treadmill speed changes, had a constant gain with no phase lag (determined by Fourier analysis) regardless the periods of oscillations. In marked contrast, when the periods of speed oscillations decreased, the amplitude (peak-to-mean) of minute ventilation (V E ) oscillations decreased sharply and significantly (from 6.1 ± 0.4 l min −1 to 1.9 ± 0.2 l min −1 ) and the phase lag between ventilation and treadmill speed oscillations increased (to 105 ± 25• during the 1 min oscillation periods). V E response followedV CO 2 very closely. The drop inV E amplitude ratio was proportional to that inV CO 2 (from 149 ± 48 ml min −1 to 38 ± 5 ml min −1 ) with a slightly longer phase lag for ventilation than forV CO 2 . These results show that beyond the onset period of a locomotor activity, the amplitude and phase lag of theV E response depends on the period of the walking speed oscillations, tracking the gas exchange rate, regardless of the amplitude of the motor act of walking. Locomotion thus appears unlikely to cause a simple parallel and proportional increase in ventilation in walking sheep.

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Stimulation of ventilation by normobaric hyperoxia in exercising dogs

Cited by 3 publications

References 20 publications

Restoration of arterial oxygen tension in horses recovering from general anaesthesia

Restoration of arterial oxygen tension in horses recovering from general anaesthesia

Control of Breathing During Exercise

The control of ventilation is dissociated from locomotion during walking in sheep

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