Monitoring brain tissue oxygen tension in brain-injured patients reveals hypoxic episodes in normal-appearing and in peri-focal tissue

Intensive Care Med. 2007 Dec;33(12):2136-42. doi: 10.1007/s00134-007-0845-2. Epub 2007 Sep 1.

Abstract

Objective: We compared brain tissue oxygen tension (PtiO2) measured in peri-focal and in normal-appearing brain parenchyma on computerized tomography (CT) in patients following traumatic brain injury (TBI).

Design: Prospective observational study.

Setting: Neurointensive care unit.

Patients and participants: Thirty-two consecutive TBI patients were subjected to PtiO2 monitoring.

Interventions: Peri-focal tissue was identified by the presence of a hypodense area of the contusion and/or within 1 cm from the core of the contusion. The position of the tip of the PtiO2 probe was assessed at follow-up CT scan.

Measurements and results: Mean PtiO2 in the peri-contusional tissue was 19.7+/-2.1 mmHg and was lower than PtiO2 in normal-appearing tissue (25.5+/-1.5 mmHg, p < 0.05), despite a greater cerebral perfusion pressure (CPP) (73.7+/-2.3 mmHg vs. 67.4+/-1.4 mmHg, p < 0.05). We observed both in peri-focal tissue and in normal-appearing tissue episodes of brain hypoxia (PtiO2 < 20 mmHg for at least 10 min), whose median duration was longer in peri-focal tissue than in normal-appearing tissue (51% vs. 34% of monitoring time, p < 0.01). In peri-focal tissue, we observed a progressive PtiO2 increase from pathologic to normal values (p < 0.01).

Conclusions: Multiple episodes of brain hypoxia occurred over the first 5 days following severe TBI. PtiO2 was lower in peri-contusional tissue than in normal-appearing tissue. In peri-contusional tissue, a progressive increase of PtiO2 from pathologic to normal values was observed over time, suggestive of an improvement at microcirculatory level.

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Aged, 80 and over
  • Brain Injuries / diagnostic imaging
  • Brain Injuries / physiopathology*
  • Cerebrovascular Circulation / physiology
  • Female
  • Humans
  • Hypoxia-Ischemia, Brain / physiopathology*
  • Italy
  • Male
  • Middle Aged
  • Monitoring, Physiologic / methods
  • Oxygen / metabolism*
  • Prospective Studies
  • Tomography, X-Ray Computed

Substances

  • Oxygen