title: Monitoring brain tissue oxygen tension in brain-injured patients reveals hypoxic episodes in normal-appearing and in peri-focal tissue.
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).
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  Neurointensive care unit.
  
  
  METHODS
  Thirty-two consecutive TBI patients were subjected to PtiO2 monitoring.
  
  
  METHODS
  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.
  
  
  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.
authors.affiliation: University of Milano, Fondazione IRCCS, Ospedale Maggiore Policlinico, Mangiagalli e Regina Elena,Neurosurgical Intensive Care Unit, Department of Anesthesia and Critical Care Medicine, Via Sforza n 35, 20100 Milan, Italy. lucalonghi@policlinico.mi.it
authors.forename: Luca
authors.initials: L
authors.lastname: Longhi
authors.forename: Francesca
authors.initials: F
authors.lastname: Pagan
authors.forename: Valerio
authors.initials: V
authors.lastname: Valeriani
authors.forename: Sandra
authors.initials: S
authors.lastname: Magnoni
authors.forename: Elisa R
authors.initials: ER
authors.lastname: Zanier
authors.forename: Valeria
authors.initials: V
authors.lastname: Conte
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Branca
authors.forename: Nino
authors.initials: N
authors.lastname: Stocchetti
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001930:Brain Injuries / Q000000981:diagnostic imaging / Q000503:physiopathology*; D002560:Cerebrovascular Circulation / Q000502:physiology; D005260:Female; D006801:Humans; D020925:Hypoxia-Ischemia, Brain / Q000503:physiopathology*; D007558:Italy; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D010100:Oxygen / Q000378:metabolism*; D011446:Prospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D010100:Oxygen