Brain tissue pO2 in relation to cerebral perfusion pressure, TCD findings and TCD-CO2-reactivity after severe head injury.
As a reliable continuous monitoring of cerebral blood flow and/or cerebral oxygen metabolism is necessary to prevent secondary ischaemic events after severe head injury (SHI) the authors introduced brain tissue pO2 (ptiO2) monitoring and compared this new parameter with TCD-findings, cerebral perfusion pressure (CPP) and CO2-reactivity over time on 17 patients with a SHI. PtiO2 reflects the balance between the oxygen offered by the cerebral blood flow and the oxygen consumption by the brain tissue. According to TCD-CO2-reactivity PtiO2-CO2-reactivity was introduced. After initially (day 0) low mean values (ptiO2 7.7 +/- 2.6 mmHg, TCD 60.5 +/- 32.0 cm/sec and CPP 64.5 +/- 16.0 mmHg/, ptiO2 increased together with an increase in blood flow velocity of the middle cerebral artery and CPP. The relative hyperaemic phase on days 3 and 4 was followed by a decrease of all three parameters. Although TCD-CO2-reactivity was except for day 0 (1.4 +/- 1.5%), sufficient, ptiO2-CO2-reactivity sometimes showed so-called paradox reactions from day 0 till day 3, meaning an increase of ptiO2 on hyperventilation. Thereafter ptiO2-CO2-reactivity increased, increasing the risk of inducing ischaemia by hyperventilation. The authors concluded that ptiO2-monitoring might become an important tool in our treatment regime for patients requiring haemodynamic monitoring.
Dings
J
J
Department of Neurosurgery, University of Wuerzburg, Federal Republic of Germany.
Meixensberger
J
J
Amschler
J
J
Hamelbeck
B
B
Roosen
K
K
D000293:Adolescent; D000328:Adult; D001783:Blood Flow Velocity / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D001921:Brain / Q000098:blood supply*; D001924:Brain Concussion / Q000503:physiopathology*; D002545:Brain Ischemia / Q000503:physiopathology; D002245:Carbon Dioxide / Q000097:blood*; D005260:Female; D016489:Head Injuries, Closed / Q000503:physiopathology*; D006407:Hematoma, Epidural, Cranial / Q000503:physiopathology; D006408:Hematoma, Subdural / Q000503:physiopathology; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D006985:Hyperventilation / Q000503:physiopathology; D007427:Intracranial Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000295:instrumentation; D010100:Oxygen / Q000097:blood*; D010101:Oxygen Consumption / Q000502:physiology*
D002245:Carbon Dioxide; D010100:Oxygen