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Updated: Apr 19, 2026
Non-invasive Optical Measurement of Cerebral Metabolism and Hemodynamics in Infants
Published on: March 14, 2013
Cerebral oxygenation during intermittent hypoxemia and bradycardia in preterm infants
Manuel B Schmid1, Reinhard J Hopfner, Susanne Lenhof
1Division of Neonatology and Pediatric Critical Care, Department of Pediatrics and Adolescent Medicine, University Medical Center Ulm, Ulm, Germany.
Insights
Apnea of prematurity can cause hypoxemia and bradycardia in preterm infants. Combined events significantly impact cerebral oxygenation more than isolated ones, though most infants maintain adequate brain oxygen levels.
Area of Science:
- Neonatal Physiology
- Neurocritical Care
- Pediatric Pulmonology
Background:
- Apnea of prematurity frequently causes hypoxemia and bradycardia in preterm infants.
- The impact of different apnea event types on infant brain oxygenation is not well understood.
Purpose of the Study:
- To investigate the influence of isolated and combined hypoxemia and bradycardia on cerebral oxygenation in preterm infants.
Main Methods:
- Near-infrared spectroscopy (NIRS) measured cerebral tissue oxygen saturation (StO2) in 16 preterm infants over 16 hours.
- Events were categorized as isolated bradycardia, isolated hypoxemia, or combined events.
- Cerebral desaturation score, duration, and depth were primary and secondary outcomes.
Main Results:
- Isolated hypoxemia was the most frequent event type; isolated bradycardia was least common.
- Combined events, particularly hypoxemia followed by bradycardia, showed the largest cerebral desaturation.
- Despite severe SpO2 drops, 12 out of 16 infants maintained cerebral StO2 above 60%.
Conclusions:
- Isolated bradycardias had minimal impact on cerebral desaturation, while combined events had the greatest impact.
- The majority of preterm infants maintained adequate cerebral oxygenation (>60%) during these events.
Background:
Episodes of hypoxemia and bradycardia frequently occur with apnea of prematurity in preterm infants. Little is known about the impact of different event types on the brain.
Objectives:
To describe the influence of hypoxemia and bradycardia, either isolated or in combination, on cerebral oxygenation.
Methods:
In 16 preterm infants with intermittent hypoxemia and/or bradycardia, cerebral tissue oxygen saturation (StO2, as measured by near-infrared spectroscopy), heart rate and pulse oximetric saturation (SpO2) were recorded simultaneously for 16 h. Events were classified as isolated bradycardia (type 1), isolated hypoxemia (type 2) or combined (simultaneous, type 3; bradycardia first, type 4; hypoxemia first, type 5). Primary outcome was a score representing the area below baseline for cerebral StO2 desaturation during an event. Secondary outcomes were duration and depth of cerebral desaturation.
Results:
Patients had a median (range) gestational age of 25.9 (22.6-30.4) weeks and a postnatal age of 32.5 (7-58) days. The median (quartiles) number of events was 49 (34-58). Isolated hypoxemias were the most frequent events (24; 9-36) and isolated bradycardias the least common (0; 0-1). Cerebral StO2 baseline was not different between event types. Cerebral desaturation score, duration of event and depth of cerebral desaturation were smallest for isolated bradycardias and largest for combined events, especially for those starting with hypoxemia followed by bradycardia. Regardless of event type, 12/16 infants maintained cerebral StO2 >60% despite severe SpO2 desaturations.
Conclusions:
Isolated bradycardias had the lowest impact on cerebral desaturation, and combined events had the highest. Most infants preserved cerebral oxygenation >60% during events.
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