Related Experiment Videos
Prolonged apnea in the preterm infant is not a random event
S A al-Saedi1, R P Lemke, Z A Haider
1University of Manitoba, Dept. of Pediatrics, Winnipeg, MB, Canada.
Insights
Prolonged apneas in preterm infants are not random. Preceding respiratory pauses and changes in breathing patterns, like decreased minute ventilation and oxygen saturation, predict these events.
Area of Science:
- Neonatal physiology
- Respiratory control
Background:
- Prolonged apneas are a significant concern in preterm infants.
- The predictive nature of preceding respiratory events is not well understood.
Purpose of the Study:
- To test the hypothesis that prolonged apneas in preterm infants are preceded by specific respiratory patterns.
Main Methods:
- Studied 36 preterm infants with apnea.
- Utilized a nosepiece system to measure ventilation and alveolar gases.
- Analyzed 10-minute windows for apneic episodes and ventilatory variables, followed by a 1-minute interval for prolonged apnea detection.
Main Results:
- The risk of prolonged apnea significantly increased with preceding apneic periods.
- Total apneic time in the prior 10 minutes was the strongest predictor.
- Before prolonged apnea, minute ventilation and respiratory frequency decreased, and oxygen saturation dropped.
Conclusions:
- Prolonged apnea in preterm infants is not random.
- It is preceded by disturbances in respiratory control, including frequent apneas, decreased ventilation, and reduced oxygen saturation.
Abstract:
We tested the hypothesis that in preterm infants, prolonged apneas (apneas > or = 20 sec) are not random events but are preceded by frequent and progressively longer respiratory pauses associated with changes in ventilatory variables. We studied 36 preterm infants with apnea [birth weight 1190 +/- 60 g (mean +/- SEM), study weight 1300 +/- 60 g, gestational age 28 +/- 1 weeks, and postnatal age 23 +/- 2 days]. A nosepiece with a flow-through system was used to measure ventilation and alveolar gases. Throughout the monitoring period for each infant we established 10-min moving "window of observation" followed by a 1-min interval examined for the detection of a prolonged apnea. Within the 10-min window, three variables were defined: the number of apneic episodes, the maximum length of a single apneic episode, and the total duration of apneic time. During the following minute (eleventh) the presence or absence of a prolonged apnea was determined. Chi-square test for a linear-trend in the rate of prolonged apnea and multiple logistic regression analysis showed that the relative risk of a prolonged apnea increases significantly from preceding periods without apnea to preceding periods containing the potential predictors of prolonged apnea. The strongest predictor was total duration of apneic time in the previous 10 min. When the 1 min before prolonged apnea was compared with the 1 min of similar sleep state not having prolonged apnea, minute ventilation decreased, primarily due to a decrease in respiratory frequency. Oxygen saturation decreased and alveolar PCO2 did not change. These findings suggest that prolonged apnea is not a random event but is preceded by a disturbance of the respiratory control system characterized by (1) frequent apneas of progressive duration, (2) decrease in respiratory minute volume and frequency, and (3) decreased O2 saturation.