AROUSAL RESPONSE TO RESPIRATORY EVENTS IN PREMATURE NEWBORNS.
Contributors: University of California, San Francisco.
Published: 1989
Number of pages: 177
Subjects: Health Sciences, Nursing.; Biology, Animal Physiology.
Description: The ability to arouse from sleep in response to respiratory events such as apnea, hypoxia, and hypercarbia is an important protective mechanism.

The following hypotheses were investigated: (1) apnea in prematures is terminated by arousal; (2) the frequency of arousals, both spontaneous and in relation to hypoxic and hypercarbic challenges will increase with postnatal age; (3) arousal will occur at a higher oxygen saturation with advancing postnatal age, and (4) arousal will occur at a lower carbon dioxide level with advancing postnatal age.

Subjects were 11 prematures with a mean gestational age at birth of 30 weeks, studied initially at a mean postnatal age of 7 weeks and again at 14.5 weeks. During sleep the following variables were recorded: heart rate, respiratory rate, oxygen saturation, skin surface oxygen and carbon dioxide, respired carbon dioxide, esophageal pressure and sleep states by behavioral criteria. Data were collected during baseline sleep while breathing room air, 17% oxygen and 2, 4, and 6% carbon dioxide.

Of 34 recorded apneic episodes 14 were interrupted by behavioral arousal. This may be evidence of maturation and integration of the reticular activating system and respiratory center.

Congruent with the above were findings that behavioral arousal at the later compared to the early postnatal age was: (1) significantly decreased during baseline sleep; (2) decreased in response to breathing 17% oxygen and 2, 4, and 6% carbon dioxide, and (3) significantly increased in REM versus NREM sleep at both postnatal ages.

In response to 17% oxygen arousal threshold was lower (i.e., mean oxygen saturation was higher) at the later postnatal age for both arousers and nonarousers, but was statistically significant by postnatal age only for the total group. Fewer subjects aroused to 17% oxygen at the later postnatal age, and mean oxygen saturation was higher at the later postnatal age, whether at arousal or at the end of 17% oxygen. In response to increased inspired carbon dioxide there was no significant difference in arousal threshold (i.e. transcutaneous carbon dioxide tension) by postnatal age or by arousal status. Fewer subjects aroused to increased inspired carbon dioxide at the later postnatal age.
Notes: Source: Dissertation Abstracts International, Volume: 50-08, Section: B, page: 3397.

Thesis (D.N.S.)--UNIVERSITY OF CALIFORNIA, SAN FRANCISCO, 1989.

School code: 0034.