A New Method of Evaluating the Chemosensitivity of the Respiratory Centre in Children

Cosgrove, John F.; Cooper, Paul D.; Bryan, A. C.; Neuburger, Naftoli; Levison, Henry

doi:10.1203/00006450-197404000-00756

Cited by 9 publications

(6 citation statements)

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“…In contrast, Derenne et al (15) reported that seated men tended to decrease their end-expiratory lung volume during CO2 rebreathing, and this finding could account for the exponential relationship between Pco2 and PI00 described by Whitelaw et al (11) and Kryger et al (8). We and others (16,17), however, have found linear relationship between Pco2 and Ploo, and we have been Effects ofage on the responses to hypercap)niia. The present study has demonstrated that ventilatory responses to hypercapnia in normal individuals fall with age.…”

Section: Resultscontrasting

confidence: 51%

Effects of hypercapnia and inspiratory flow-resistive loading on respiratory activity in chronic airways obstruction.

et al. 1977

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A B S T R A C T The respiratory responses to hypercapnia alone and to hypercapnia and flow-resistive loading during inspiration were studied in normal individuals and in eucapnic and hypercapnic patients with chronic airways obstruction. Responses were assessed in terms of minute ventilation and occlusion pressure (mouth pressure during airway occlusion 100 ms after the onset of inspiration).Ventilatory responses to CO2 (AV/APco2) were distinctly subnormal in both grouips of patients with airways obstruction. The two groups of patients, however, showed different occlusion pressure responses to CO2 (AP100/APCo2): AP100/APCo2 was normal in the eucapnic patients but subnormal in the hypercapnic patients. Flow-resistive loading during inspiration reduced AV/APCo2 both in normal subjects and in patients with airways obstruction. The occlusion pressure response to CO2 increased in normal subjects during flow-resistive loading but remained unchanged in both grouips of patients with chronic airways obstruction.These results indicate that while chemosensitivity as determined by AP100dAPCo2 is impaired only in hypercapnic patients with chronic airways obstruction, an acute increase in flow resistance elicits a subnormal increase in respiratory efferent activity in both euicapnic and hypercapnic patients.

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Section: Resultscontrasting

confidence: 51%

Effects of hypercapnia and inspiratory flow-resistive loading on respiratory activity in chronic airways obstruction.

et al. 1977

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“…Occlusion pressure was also measured at 100 msec after the airway was occluded (PIOO), as this may more accurately reflect the respira-tory center's activity in case the occlusion elicits a voluntary response (4). The inspiratory duration of the unoccluded breath (Ti) was measured from the inspiratory flow tracing preceeding the occluded breath.…”

Section: Methodsmentioning

confidence: 99%

“…The advantage of this method over measuring changes in minute ventilation is its decreased dependence on the mechanical properties of the respiratory system (4,13). In addition, the airway occlusion technique allows the evaluation of the reflex influence on inspiratory timing (32,35) and the effective elastance of the respiratory system (23).…”

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confidence: 99%

Effects of Aminophylline on Respiratory Center and Reflex Activity in Premature Infants with Apnea

1983

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SummaryFourteen preterm infants with apnea (body weight, 1052 + 44 g; gestational age, 30.2 f 0.5 wks; and postnatal age, 9.9 f 1.5 days) were studied in an effort to evaluate the effects of aminophylline on respiratory center output and respiratory reflex activity in the preterm infant with idiopathic apnea. This was done by using the airway occlusion technique. The infants were studied before and 48 h after aminophylline was begun as a treatment for apnea. Occlusion pressure, which reflects respiratory center output, was measured at 100 msec after occlusion started (P100) and at its maximum (Prno). PlOO increased from 2.4 + 0.2 to 3.1 + 0.2 cmHzO ( P < 0.005), and Pmo from 6.1 f 0.7 to 8.8 + 1.0 cmH20 ( P < 0.001) after aminophylline therapy was started.The % prolongation of inspiratory time during the occluded breaths, when compared to the unoccluded breaths increased from 26.2 f 10.6 to 55.8 + 12.5% ( P < 0.01). This reflects a significant increase in the strength of the Hering Breuer reflex. Effective elastance, a measure of respiratory load compensation, was significantly higher during aminophylline treatment. It increased from 1.09 + 0.14 to 1.33 & 0.14 cmHzO/ml ( P < 0.02).Abbreviations E'rs, effective elastase of the respiratory system Pmo, maximal occlusion pressure Ti, inspiratory time Tiocc, inspiratory time of the occluded breath VT, tidal volume before occlusion Aminophylline is widely used for the treatment of idiopathic apnea of prematurity without a full understanding of its mode of action. In two previous studies (10, I 1) we showed that premature infants with apnea had decreased alveolar ventilation and hypercapnea. This was in part secondary to a large deadspace ventilation and a decreased respiratory center sensitivity to COz. Aminophylline increased ventilation in these infants by lowering respiratory center threshold to COz, without affecting lung function.The purpose of this study was to evaluate in preterm infants with apnea the effect of aminophylline on respiratory center output, reflex influence on inspiratory timing, and effective elastance of the respiratory system.-his was done by using the airway occlusion technique described by Grunstein et al. (13) and Olinsky et al. (23). The advantage of this method over measuring changes in minute ventilation is its decreased dependence on the mechanical properties of the respiratory system (4, 13). In addition, the airway occlusion technique allows the evaluation of the reflex influence on inspiratory timing (32, 35) and the effective elastance of the respiratory system (23). The latter has been used as a measure of the stability of the system when exposed to respiratory loads (19,21,23).

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“…However, data to calculate these parameters were obtained from two papers. Using Read's rebreathing method, COSGROVE et al (1975) studied C02 chemosensitivity of 43 subjects ranging in age from 6.5 to 50 yrs. Japanese Journal of Physiology Fig.…”

Section: Discussionmentioning

confidence: 99%

Hypercapnic and hypoxic ventilatory responses during growth.

et al. 1986

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Cross-sectional studies on hypercapnic and hypoxic ventilatory chemosensitivities were performed in 71 children ranging in age from 7 to 18 yrs. The subjects were classified into 6 successive 2-year age groups. CO2 ventilatory response was measured by rebreathing 5 % CO2 in Oz, a slight modification of the method originally proposed by Read. The results were evaluated when the C02-ventilation feedback control system was supposed to have attained the open-loop condition. Hypoxic ventilatory response was measured by the isocapnic progressive hypoxia test. To obtain good reproducibility in the ventilatory response, end-tidal P~oz was maintained at 5 mmHg higher than the resting condition throughout the test. Normalized ventilatory responses to CO2 by body surface area (S/BSA) progressively decreased from the 7-8 through the 11-12 yr groups, and then tended to decrease further in a more gradual manner with increasing age. This trend was very similar to the normalized CO2 output (V"oz/BSA), but did not parallel so closely the normalized Oz intake (Voz/BSA). When ventilatory and metabolic parameters were normalized by body weight (BW), or the lean body mass (LBM), qualitatively similar relationships between CO2 sensitivities and metabolic parameters were also obtained. Contrary to the hypercapnic response, hypoxic ventilatory chemosensitivities were not significantly different among the 6 different age groups. We concluded that normalized hypercapnic chemosensitivity decreased during growth and corresponded well with decreased CO2 output per unit body mass.Key words : hypercapnic ventialtory response, hypoxic ventilatory response, body weight, body surface area, lean body mass.

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A New Method of Evaluating the Chemosensitivity of the Respiratory Centre in Children

Cited by 9 publications

References 0 publications

Effects of hypercapnia and inspiratory flow-resistive loading on respiratory activity in chronic airways obstruction.

Effects of hypercapnia and inspiratory flow-resistive loading on respiratory activity in chronic airways obstruction.

Effects of Aminophylline on Respiratory Center and Reflex Activity in Premature Infants with Apnea

Hypercapnic and hypoxic ventilatory responses during growth.

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