Influence of body position on pressure and airflow generation during hypoxia and hypercapnia in man.

Xie, Ailiang; Takasaki, Yoshito; Popkin, J.; Orr, David W.; Bradley, T. Douglas

doi:10.1113/jphysiol.1993.sp019688

Cited by 14 publications

(12 citation statements)

References 32 publications

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“…Our previous study has shown that in contrast to the hypercapnic ventilatory response, the hypoxic ventilatory response decreases in the head-down position [5]. These data are in accord with the results of studies in which hypoxic ventilatory responses were compared in the standing or sitting postures compared with the supine position [4,9]. Thus, change in the body position affects differentially hypoxic and hypercapnic sensitivity of the breathing system, decreasing the ventilatory response to hypoxia, but not to hypercapnia.…”

Section: Discussionsupporting

confidence: 86%

Effects of body position on the ventilatory response to hypercapnia

Donina

Aleksandrova

2009

Eur J Med Res

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Effect of posture on the hypercapnic ventilatory response was studied on the anaesthetized rats by using rebreathing techniques in the supine and head-down positions. There were no statistically significant alterations in tidal volume, frequency, minute ventilation, and PETCO2 between the head-down and supine positions during breathing at rest. However, the esophageal pressure inspiratory swings were significantly greater in the head-down compared with supine position. Moreover, we found that body position did not affect the hypercapnic ventilatory response, but did affect the relationship between inspiratory driving pressure and the increase of end tidal PCO2. Greater inspiratory pressure is required to maintain the same level of the ventilatory response to hypercapnia in the horizontal position with the head-down. We believe that the discrepancy between postural alterations in the hypercapnic ventilatory and pressure responses is presumably a result of decreased lung compliance and increased airflow impedance of respiratory system in the head-down position.

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Section: Discussionsupporting

confidence: 86%

Effects of body position on the ventilatory response to hypercapnia

Donina

Aleksandrova

2009

Eur J Med Res

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“…We conducted the CO 2 challenges in the PRBS test with our subjects in the sitting instead of in the supine position, in order to maintain wakefulness. Some differences in control of breathing responsiveness may exist in these two body positions (11), but in the study by Xie and colleagues (11), the hypercapnic response was affected less than the hypoxic response. In the present study, both control subjects and OSA patients were studied in the sitting position.…”

Section: Technical Considerationsmentioning

confidence: 93%

Instability of Ventilatory Control in Patients with Obstructive Sleep Apnea

Hudgel

Gordon

Thanakitcharu

et al. 1998

Am J Respir Crit Care Med

107

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Because of the oscillatory pattern of upper airway resistance and breathing during sleep in patients with obstructive sleep apnea (OSA), we hypothesized that OSA patients have an underlying instability of ventilatory drive to inspiratory muscles. To assess the stability of ventilatory drive in OSA patients and controls, we used the pseudorandom binary stimulation (PRBS) test and examined the closed-and open-loop responses to hyperoxic hypercapnia. The closed-loop response is produced by interactions of dynamic gain in controller, plant, and ventilatory feedback. The open-loop response reflects controller dynamic gain or frequency-dependent chemosensitivity. As compared with 16 nonapneic, nonobese control subjects, a group of nine obese OSA patients had a higher peak response and a more rapid and irregular recovery phase of the closed-loop CO 2 response in the PRBS test. The two groups had similar open-loop responses in the PRBS test, suggesting that central dynamic CO 2 chemosensitivity was not abnormal in OSA. We conclude that the differences between OSA patients and controls in the closed-loop response in the PRBS test are not due to differences in dynamic controller gain, but are related to differences in dynamic plant gain and/or negative ventilatory feedback. In addition to OSA, obesity may affect these variables and may have been responsible for our findings. Hudgel DW, Gordon EA, Thanakitcharu S, Bruce EN. Instability of ventilatory control in patients with obstructive sleep apnea.

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“…In the supine position there is a lower slope of HVR due to greater air flow impedance and limitation of peak inspiratory pressure [12]. The vital capacity (VC) decreases by 7% in the supine position.…”

Section: Discussionmentioning

confidence: 99%

“…The effects of body position on ventilatory responses to hypoxia and hypercapnia have been characterized in normal subjects [10][11][12]. In the supine position there is a lower slope of HVR due to greater air flow impedance and limitation of peak inspiratory pressure [12].…”

Section: Discussionmentioning

confidence: 99%

Hypoxic Ventilatory Responses and Gas Exchange in Patients with Parkinson’s Disease

et al. 1998

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Ventilatory responses to isocapnic, progressive hypoxic rebreathing (HVR), in supine and sitting positions, lung ventilation and gas exchange while breathing air and during 5 min of breathing 11% O₂ in N₂ were studied in 12 healthy young (20–28 years), 5 old (57–73 years) male subjects, and in 7 male patients with Parkinson’s disease (PD) aged 55–67 years. The piecewise linear approximation technique was used for evaluation of the ventilatory response curves, which allowed a separate analysis of slopes during minor and severe hypoxia. It has been shown that body position affected HVR. In the range of P_ETO₂ from 60 to 35 mm Hg, the ventilatory response in the sitting position was higher than supine: in young persons by 43%, in healthy old persons by 76%, and in the PD patients by 211%. No significant differences in HVR to minor hypoxia (P_ETO₂ from 100 to 60 mm Hg) were found in the 3 groups. During severe hypoxia (P_ETO₂ from 60 to 35 mm Hg) the slope of minute ventilation versus O₂ was 4.6 (supine) and 2.6 (sitting) times greater in healthy old men than PD patients’ slopes. PD patients compared to old controls had 32% lower alveolar ventilation, 10% lower P_ETO₂ and 15% elevation of P_ETCO₂ while breathing air; similar differences were found while the patients were breathing 11% O₂. The reduced alveolar ventilation under severe hypoxia in patients with PD could not be attributed to mechanical restriction of lung function. We suggest that the discrepancy in HVR under minor and severe hypoxia results from dysfunction in chemoreception associated with Parkinsonism.

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Influence of body position on pressure and airflow generation during hypoxia and hypercapnia in man.

Cited by 14 publications

References 32 publications

Effects of body position on the ventilatory response to hypercapnia

Effects of body position on the ventilatory response to hypercapnia

Instability of Ventilatory Control in Patients with Obstructive Sleep Apnea

Hypoxic Ventilatory Responses and Gas Exchange in Patients with Parkinson’s Disease

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