Speed and profile of the arterial peripheral chemoreceptors as measured by ventilatory changes in preterm infants.
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] during inhalation of 21% O2 (15 +/- 5 s) followed by 100% O2 (1 min). We used a flow-through system to measure ventilation and gas analyzers to measure alveolar gases. Hypoventilation was observed at 3.6 +/- 0.6 s and was maximal at 6.8 +/- 1 s after O2 began. This maximal response was always associated with an apnea (greater than 3 s). Alveolar PO2 increased from 13.5 +/- 0.1 kPa (101 +/- 0.8 torr) (control) to 28.0 +/- 1.2 kPa (210 +/- 9 torr) (1st O2 breath), to 42.0 +/- 2.4 kPa (315 +/- 18 torr) (1st hypoventilation), to 45.9 +/- 4.1 kPa (344 +/- 31 torr) (breath preceding maximal response), and to 53.6 +/- 4.1 kPa (402 +/- 31 torr) (at maximal response). Minute ventilation was 0.192 +/- 0.011 (control), 0.188 +/- 0.011 (1st O2 breath), 0.088 +/- 0.016 (1st hypoventilation; p less than 0.0001), 0.122 +/- 0.016 (breath preceding maximal response; p less than 0.0002), and 0.044 +/- 0.011 L/min/kg at maximal response (p less than 0.0001). This decrease in ventilation was due to a decrease in frequency with no appreciable change in tidal volume. The initial period of hypoventilation (19 +/- 4 s) was followed by a breathing interval (10 +/- 2 s) and a second period of hypoventilation (14 +/- 3 s) before continuous breathing resumed.(ABSTRACT TRUNCATED AT 250 WORDS)
Alvaro
R E
RE
Department of Pediatrics, University of Manitoba, Winnipeg, Canada.
Weintraub
Z
Z
Kwiatkowski
K
K
Cates
D B
DB
Rigatto
H
H
D001158:Arteries / Q000294:innervation; D002628:Chemoreceptor Cells / Q000502:physiology*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology*; D010100:Oxygen; D012119:Respiration / Q000502:physiology*
D010100:Oxygen