This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a colleague Similar articles in this journal Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Kurth, C. D. Articles by Loepke, A. W. Search for Related Content PubMed Articles by Kurth, C. D. Articles by Loepke, A. W. Related Collections Mechanisms Neuroanesthesia Complications Monitoring (Non-cardiac) Patient Safety

---

NEUROSURGICAL ANESTHESIOLOGY AND NEUROSCIENCE

Cerebral Oxygen Saturation-Time Threshold for Hypoxic-Ischemic Injury in Piglets

From the Departments of Anesthesiology, Pathology, and Pediatrics, Cincinnati Children's Hospital, University of Cincinnati College of Medicine, Cincinnati, Ohio.

Address correspondence and reprint requests to C. Dean Kurth, MD, Department of Anesthesiology, Cincinnati Children's Hospital, 3333 Burnet Ave., ML-2001, Cincinnati, OH 45229-3039. Address e-mail to dean.kurth{at}cchmc.org.

Abstract

BACKGROUND: Detection of cerebral hypoxia-ischemia (H-I) and prevention of brain injury remains problematic in critically ill neonates. Near-infrared spectroscopy (NIRS), a noninvasive bedside technology could fill this role, although NIRS cerebral O₂ saturation (Sc_O2) viability-time thresholds for brain injury have not been determined. We investigated the relationship between H-I duration at Sc_O2 35%, a viability threshold which causes neurophysiological impairment, to neurological outcome.

METHODS: Forty-six fentanyl-midazolam anesthetized piglets were equipped with NIRS and cerebral function monitor (CFM) to record Sc_O2 and electrocortical activity (ECA). After carotid occlusion, inspired O₂ was adjusted to produce H-I (Sc_O2 35% with decreased ECA) for 1, 2, 3, 4, 6 or 8 h in different groups, followed by survival to assess neurological outcome by behavioral and histological examination.

RESULTS: For H-I lasting 1 or 2 h, ECA and Sc_O2 during reperfusion rapidly returned to normal and neurological outcomes were normal. For H-I more than 2–3 h, ECA was significantly decreased and Sc_O2 was significantly increased during reperfusion, suggesting continued depression of tissue O₂ metabolism. As H-I increased beyond 2 h, the incidence of neurological injury increased linearly, approximately 15% per h.

CONCLUSION: A viability-time threshold for H-I injury is Sc_O2 of 35% for 2–3 h, heralded by abnormalities in NIRS and CFM during reperfusion. These findings suggest that NIRS and CFM might be used together to predict neurological outcome, and illustrate that there is a several hour window of opportunity during H-I to prevent neurological injury.

This article has been cited by other articles:

				M. Smith and C. Elwell Near-Infrared Spectroscopy: Shedding Light on the Injured Brain Anesth. Analg., April 1, 2009; 108(4): 1055 - 1057. [Full Text] [PDF]