The frequency of cerebral ischemia/hypoxia in pediatric severe traumatic brain injury.
BACKGROUND
The frequency of adverse events, such as cerebral ischemia, following traumatic brain injury (TBI) is often debated. Point-in-time monitoring modalities provide important information, but have limited temporal resolution.


OBJECTIVE
This study examines the frequency of an adverse event as a point prevalence at 24 and 72 h post-injury, compared with the cumulative burden measured as a frequency of the event over the full duration of monitoring.


METHODS
Reduced brain tissue oxygenation (PbtO(2) < 10 mmHg) was the adverse event chosen for examination. Data from 100 consecutive children with severe TBI who received PbtO(2) monitoring were retrospectively examined, with data from 87 children found suitable for analysis. Hourly recordings were used to identify episodes of PbtO(2) less than 10 mmHg, at 24 and 72 h post-injury, and for the full duration of monitoring.


RESULTS
Reduced PbtO(2) was more common early than late after injury. The point prevalence of reduced PbtO(2) at the selected time points was relatively low (10 % of patients at 24 h and no patients at the 72-h mark post-injury). The cumulative burden of these events over the full duration of monitoring was relatively high: 50 % of patients had episodes of PbtO(2) less than 10 mmHg and 88 % had PbtO(2) less than 20 mmHg.


CONCLUSIONS
Point-in-time monitoring in a dynamic condition like TBI may underestimate the overall frequency of adverse events, like reduced PbtO(2), particularly when compared with continuous monitoring, which also has limitations, but provides a dynamic assessment over a longer time period.
Pediatric Neurosurgery, School of Child and Adolescent Health, Red Cross War Memorial Children's Hospital, University of Cape Town, Rondebosch 8001, Cape Town, South Africa. llewesp@yahoo.com
Llewellyn C
LC
Padayachy
Ursula
U
Rohlwink
Eugene
E
Zwane
Graham
G
Fieggen
Jonathan C
JC
Peter
Anthony A
AA
Figaji
D000293:Adolescent; D000367:Age Factors; D001921:Brain / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology*; D001930:Brain Injuries / Q000150:complications*; D002648:Child; D002675:Child, Preschool; D005260:Female; D015600:Glasgow Coma Scale; D006801:Humans; D020925:Hypoxia-Ischemia, Brain / Q000175:diagnosis / Q000209:etiology*; D007223:Infant; D007427:Intracranial Pressure / Q000502:physiology*; D008297:Male; D010100:Oxygen / Q000378:metabolism; D010372:Pediatrics; D012189:Retrospective Studies; D013997:Time Factors
D010100:Oxygen