Oxygen Chemoreceptors in Low Birth Weight Infants

Krauss, Alfred N.; Tori, Carlos A; Brown, Jeffrey L.; Soodalter, Jane; Auld, Peter A. M.

doi:10.1203/00006450-197306000-00004

Cited by 17 publications

(6 citation statements)

References 11 publications

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“…single chemoreceptor fiber also showed an immediate (after a few seconds) decrease in the number of nerve impu lses per unit of time when the animal was made hyperoxic by breathing pure O2 (12)(13)(14). In the present study, the speed of the response (3.6 ± 0.6 and 6.8 ± 1 s for the 1st breath with hypoventilation and maximal response, respectively) was similar to that found by Girard et al The decrease in ventilation with inhaled O 2 is related to a primary decrease in frequency in preterm infants (2)(3)(4)16). The decrease in frequency is related to apnea, which commonly occurs with 100% O 2 • Term infants and adult subjects do not become apneic with high inhaled O 2 mixtures, but they change ventilation by primarily decreasing tidal volume (1,11,(17)(18)(19)(20).…”

Section: Discussionsupporting

confidence: 77%

Speed and Profile of the Arterial Peripheral Chemoreceptors as Measured by Ventilatory Changes in Preterm Infants

et al. 1992

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MATERIALS AND METH ODSchemo receptor response could be determined in "healthy" preterm infants by measuring the changes in ventilation indu ced by inha lation of 100% O 2 • Subjects. We studied 13 healthy preterm infants with a birth weight of 1602 ± 230 g (mean ± SEM), a study weight of 1652 ± 260 g, a gestational age of 31 ± 1 wk, and a postnatal age of 15 ± 1 d. The study was approved by the faculty committee on the use of human subjects in research, University of Manitoba, and written parental consent was obtained from one of the parents.M ethods. We have previously described the system to measure ventilation (6, 7). Briefly, we used a nosepiece and a screen flowmeter to measure respiratory minu te volume and alveolar gases. We used a constant background flow (3 L'min) to eliminate valves and to reduce dead space. T he infant breathed through the nostril adapters and added to (expiration) or subtracted (inspiration) flow from the background flow. This background flow was electrically balan ced to an artificial zero.We monitored breath-to-breath alveolar P0 2 and Pco, using Beckman analyzers. The 95% rise times of the analyzers were 0. 16 and 0.18 s for CO2 and O2, respectively. T he EEG was monitored using a single channel with an electrode placed in the right frontal position and referenced to the left mastoid. Th e electrooculogram was recorded from eye electrodes referenced to the right ear. Oxygen saturations and ECG were used to monitor the infant' s well-being but not as an end point of this study. Sleep state was monitored according to previous criteria (4). All variables were recorded on a polygraph (model 4221, Nihon Kohden , Tokyo, Japan ).Procedure . Infants were studied on the Ohio Neonatal Intensive Care Unit (Ohio Medical Products, Madison , WI) in a neut ral thermal environment with skin abdominal temperature at 36.5 ± 0.03°C. After appropriate placement of the various electrodes and the nosepiece, infant s were allowed to sleep. Once they had been in quiet sleep breathi ng 21% O 2 for 2 min, 100% O 2 was given for I min. Minute ventilation, tidal volume, frequency, alveolar Po 2 , alveolar Pco-, inspiratory drive, and the "duty cycle" were measured breath by breath during 2 1% O2 (I S ± 5 s) and during 100% O 2 ( I min ).Data collection and analysis. We analyzed the records by hand and transferred the data to a com puter for appropriate treatment. Control values were taken from the last eight breaths preceding the adm inistration of O 2 • The speed of the response was measured from the initiation of inspiration imm ediately after the increase in fraction of inspired O2• We used a paired t test to assess the significance of the differences between control values and those obtained in response to 100% O 2 • To find the 1st breath after 100% O 2 showing hypoventilation, we used a variation of the 226 ABSTRACf. To measure the response time of the peripheral chemoreceptors, we studied 13 preterm infants [birth weight 1602 ± 230 g (mean ± SEM); gestational age 31 ± 1 wk; postnatal age 15 ± 1 d) dur...

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Section: Discussionsupporting

confidence: 77%

Speed and Profile of the Arterial Peripheral Chemoreceptors as Measured by Ventilatory Changes in Preterm Infants

et al. 1992

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“…It canthusbeused for quantitative estimation of minute volume during intensive care monitoring, and may be of special value in evaluating changes in blood gas tensions in patients with congenital heart disease or respiratory distress syndrome. This method has already been used to evaluate the presence of respiratory reflexes [8] and apnea [9] since it has the advantage of avoiding Stimulation of the infant's face by masks or nose valves. Transthoracic impedance plethysmography is a method which deserves wider use in the care and study of the neonate.…”

Section: Discussionmentioning

confidence: 99%

Quantitative estimation of ventilation in newborn infants using the impedance pneumogram

Li¹,

Krauss²,

Auld³

1977

Journal of Perinatal Medicine

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Impedance pneumography is potentially a non-invasive method of measuring infant tidal volumes. In order to evaluate the accuracy of impedance pneumography, eight healthy infants (weighing from 709 to 3506 grams) were randomly chosen and studied. Simultaneous measurements of tidal volumes were made by calibrated spirometry and by transthoracic impedance pneumography. The results were statistically compared. Transthoracic impedance pneumography provided a reliable estimate of tidal and minute volumes in these newborn infants.

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“…The data obtained in this study of premature infants suggest that the infants who appear to be unresponsive to C 0 2 are either ( 1 ) performing respiratory work at the maximum rate possible or (2) truly lack reflexes for C 0 2 sensitivity. Since chemoreceptors for oxygen appear t o be present in the most immature infants (8,12), one might reason that nonresponsive infants lack the ability t o increase their pulmonary work. This matter awaits further investigation.…”

Section: Discussionmentioning

confidence: 99%