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Continuous monitoring of PO2 during apnea of prematurity
Insights
Hypoxia does not initiate apnea in premature infants. Oxygen levels continue to drop post-apnea, with slower recovery than the fall, and bradycardia isn't linked to low oxygen.
Area of Science:
- Neonatology
- Pediatric Pulmonology
- Respiratory Physiology
Background:
- Apnea of prematurity is common in low-birth-weight infants.
- The role of hypoxia in initiating apnea is debated.
Purpose of the Study:
- To investigate the relationship between oxygen levels and apnea in premature infants.
- To determine if hypoxia triggers apnea or bradycardia.
Main Methods:
- Monitored 72 apnea episodes in 20 low-birth-weight infants.
- Measured partial pressure of oxygen (PO2) before, during, and after apnea.
Main Results:
- 65% of episodes had stable PO2 before apnea.
- Only 18% showed falling PO2 prior to apnea; no infant was hypoxic.
- Mean PO2 fell from 75 mm Hg to 46 mm Hg post-apnea.
- Arterial oxygen tension continued to fall post-respiration, with slower recovery.
Conclusions:
- Hypoxia is not the initiating event in apnea of prematurity.
- Bradycardia associated with apnea is not initiated by hypoxemia.
- Recovery from apnea is slower than the rate of oxygen level decrease.
Abstract:
We studied the changes in PO2 during 72 isolated episodes of apnea of prematurity in 20 low-birth-weight infants. A stable PO2 prior to the onset of apnea was observed in 65% of the episodes. A falling PO2 was noted in only 18% of the cases. The mean initial PO2 was 75 mm Hg and no infant was hypoxic (PO2less than 40 mm Hg) immediately prior to apnea. The mean PO2 fell to 60 mm Hg at the end of apnea and continued to fall to a mean low PO2 of 46 mm Hg. The mean PO2 at recovery was 79 mm Hg. We concluded that in this group of premature infants, hypoxia is not the initiating even in the apnea of prematurity. Furthermore, we noted that arterial oxygen tension continues to fall despite the reestablishment of respiratory efforts, that the rate of recovery from apnea is slower than the rate of fall, and that bradycardia associated with apnea is not initiated by hypoxemia.