An Acute Reduction in the Fraction of Inspired Oxygen Increases Airway Constriction in Infants with Chronic Lung Disease

Wg, Teague; Ms, Pian; Gp, Heldt; Wh, Tooley

doi:10.1164/ajrccm/137.4.861

Cited by 49 publications

(9 citation statements)

References 6 publications

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“…For example, hypoxic stimulation in piglets is associated with an increase in both phrenic neural output and contractile responses in peripheral airways and/or lung parenchyma, which are cholinergically mediated (5). This is consistent with the clinical observation that an acute reduction in inspired oxygen may lead to airway constriction in infants with chronic lung disease (6).…”

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confidence: 83%

Effects of Hypoxia on Respiratory Neural Output and Lower Esophageal Sphincter Pressure in Piglets

et al. 2002

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We have previously documented anatomic and functional relationships between ventilatory and autonomic neural output. Therefore, we hypothesized in this study that hypoxia-induced changes in respiratory neural output are associated with changes in autonomic regulation of lower esophageal sphincter (LES) pressure. Respiratory neural output, heart rate, and LES pressure were measured before and during a 3-min exposure to 8% oxygen (balance nitrogen) in 12 3-to 7-d-old piglets. Respiratory neural output was determined from diaphragmatic electromyogram and LES pressure from an esophageal catheter. Studies were repeated after atropine administration in eight animals. Hypoxic exposure resulted in significant increases in diaphragmatic amplitude, respiratory rate, and minute diaphragmatic activity as well as heart rate. The biphasic response of diaphragm amplitude peaked at 1 min, whereas the responses of respiratory frequency and heart rate were sustained. Hypoxia caused a 50% increase in LES pressure (p Ͻ 0.05), which was eliminated by i.v. atropine administration. Development of apnea during subsequent hyperoxic exposure was always followed by a decline in LES pressure. Hypoxia-induced increase in respiratory neural output and accompanying increase in heart rate are associated with enhanced constrictive output to the LES. Blockade by atropine implicates a peripheral cholinergic mechanism for this LES response. We speculate that whereas hypoxia in the presence of enhanced respiratory neural output seems to be protective against reflux, decreased respiratory drive and accompanying apnea may be associated with a decline in LES tone and predispose to gastroesophageal reflux. Neuroanatomic studies have identified that neuronal circuits involved in coordination of respiratory control are linked to parasympathetic motor output from vagal preganglionic neurons in the brainstem (1, 2). A functional role for such interconnections has been documented in several species, including puppies and piglets (3, 4). For example, hypoxic stimulation in piglets is associated with an increase in both phrenic neural output and contractile responses in peripheral airways and/or lung parenchyma, which are cholinergically mediated (5). This is consistent with the clinical observation that an acute reduction in inspired oxygen may lead to airway constriction in infants with chronic lung disease (6).Vagal preganglionic neurons, including neurons of the DMV, also contribute preganglionic parasympathetic motor innervation to the LES (7). Therefore, alterations in respiratory neural output elicited by chemoreceptor stimulation might be expected to modulate LES pressure. This would be of particular interest during early maturation, as recurrent apnea with resultant desaturation and gastroesophageal reflux are both common in premature infants, although their relationship is controversial (8 -11) and difficult to simulate in an animal model. In the current study, we therefore used a piglet model to test the hypothesis that hypoxia-induced changes in r...

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confidence: 83%

Effects of Hypoxia on Respiratory Neural Output and Lower Esophageal Sphincter Pressure in Piglets

et al. 2002

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“…Infants recovering from respiratory distress syndrome have lower dynamic compliance than normal preterm infants (3) and increased baseline airway resistance compared with expected control values (2). Thus, a given stimulus may be equally rec- Because pulmonary mechanical function was not measured in the infants with BPD, we do not know the peak inspiratory flow rates achieved to maintain adequate ventilation.…”

Section: Discussionmentioning

confidence: 99%

Absence of Ventilatory Responses to Alternating Breaths of Mild Hypoxia and Air in Infants Who Have Had Bronchopulmonary Dysplasia: Implications for the Risk of Sudden Infant Death

et al. 1994

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ABSTRACT. Infants who have had bronchopulmonary dysplasia (BPD) are at an increased risk of sudden infant death syndrome. Because failure of the cardiorespiratory response to hypoxia is suggested to play a key role in sudden infant death syndrome, we tested the hypothesis that infants who have had BPD have a reduced respiratory chemoreflex response to hypoxia. We examined the reflex respiratory responses to breath-by-breath alternations in fractional inspired oxygen concentration in eight infants who had had BPD (mean gestation = 27 wk, mean postnatal age = 93 d) who were no longer on supplemental oxygen and compared the responses with those of 12 preterm infants who had not required supplemental oxygen or been mechanically ventilated since birth (mean gestation = 30 wk, mean postnatal age = 38 d). For test runs we alternated fractional inspired oxygen concentration through two gas delivery lines between 0.21 and 0.16 on a breath-by-breath basis, and for control runs we alternated the inspirate between the two gas lines with a fractional inspired oxygen concentration of 0.21 in each. Respiration was measured using inductance plethysmography. infants with BPD showed no significant differences between test and control responses for any respiratory variable. In contrast, all respiratory variables in the preterm infants showed test responses significantly greater than control. We speculate that the "blunted" chemoreflex respiratory response seen in infants with BPD may predispose them to subsequent respiratory failure, but we do not know which component of the chemoreflex is impaired. (Pediatr Res 35: 677481,1994)

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“…In animals inspiratory hypoxia has a direct impact on the tone of bronchial smooth muscles resulting in an increase in airway resistance (D'Brot and Ahmed 1991;Dewachter et al 1992), whereas inspiratory hyperoxia induced slight bronchodilation (D'Brot and Ahmed 1991;Libby et al 1981;Murchie et al 1993). In healthy subjects, a slight hypoxia-induced increase in airway resistance was observed whereby pronounced inter-individual differences were found (Dillard et al 1998;Saunders et al 1977;Teague et al 1988). In the present study, a very slight reduction in airway resistance was found in healthy control subjects with reduced environmental pressure (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…However, this reduction was small and may be due to a practice effect after performing three forced lung-function tests. In patients, Teague et al (1988) measured airway resistance in infants with chronic lung diseases during reduction of the inspiratory O 2 fraction to 17% and found an increase in resistance of 55% and a reduction in the dynamic lung compliance of 24%, with large inter-individual differences. In addition, the reduced cabin humidity due to the lower ambient pressure may increase the risk of acute bronchoconstriction even though there are no data to quantify this risk (British Thoracic Society Standards of Care Committee 2002).…”

Section: Discussionmentioning

confidence: 99%

“…Inspiratory hypoxia has impact on the tone of the bronchial smooth muscles resulting in hypoxia-induced bronchoconstriction accompanied by an increase in airway resistance (D'Brot and Ahmed 1991;Dewachter et al 1992;Saunders et al 1977;Teague et al 1988) and, conversely, inspiratory hyperoxia reduces the hypoxiainduced increase in pulmonary resistance (D'Brot and Ahmed 1991;Murchie et al 1993). This study followed changes in blood gases in arterialized capillary blood and lung function in CF patients under moderate inspiratory isocapnic hypoxia by hypobaric conditions.…”

Section: Introductionmentioning

confidence: 99%

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Respiratory function and blood gas variables in cystic fibrosis patients during reduced environmental pressure

Thews

B²,

Kamin³

et al. 2004

Eur J Appl Physiol

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Patients with cystic fibrosis (CF) suffer from hypoxaemia even under normobaric conditions and the reduction of inspiratory PO2 (O2 partial pressure) during air travel corresponding to an altitude of 1,800-2,450 m might be a problem for these patients. Ten CF patients and 27 healthy control subjects were investigated in a chamber where the ambient pressure was reduced to that found at 2,000 and 3,000 m. The respiratory function was reduced in the CF patients with a vital capacity of 3.1 (0.3) l [vs 4.9 (0.2) l in controls; mean (SEM)] and a forced expiratory 1-s volume of 2.1 (0.3) l [vs 4.3 (0.20 l in controls], unrelated to the reduction in ambient pressure. Mean arterial PO2 decreased from 75 (4) mmHg [85 (1) mmHg in controls, P<0.01] at sea level to 58 (3) mmHg at 580 mmHg and to 46 (1) mmHg [58 (1) mmHg and 49 (2) mmHg in controls, n.s.] at 513 mmHg ambient pressure. These results indicate that during air travel with a cabin pressure that corresponds to an altitude of 2,500 m, the arterial PO2 of CF patients is likely to remain above the accepted critical value of 50 mmHg. However, a further reduction of the pressure to that found at 3,000 m altitude may lead to severe hypoxia in patients with moderate airway obstruction.

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An Acute Reduction in the Fraction of Inspired Oxygen Increases Airway Constriction in Infants with Chronic Lung Disease

Cited by 49 publications

References 6 publications

Effects of Hypoxia on Respiratory Neural Output and Lower Esophageal Sphincter Pressure in Piglets

Effects of Hypoxia on Respiratory Neural Output and Lower Esophageal Sphincter Pressure in Piglets

Absence of Ventilatory Responses to Alternating Breaths of Mild Hypoxia and Air in Infants Who Have Had Bronchopulmonary Dysplasia: Implications for the Risk of Sudden Infant Death

Respiratory function and blood gas variables in cystic fibrosis patients during reduced environmental pressure

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