Cerebrovascular autoregulation, CO2 reactivity and outcome in patients with severe traumatic brain injury: a pilot study
© BioMed Central Ltd 2005
Published: 9 June 2005
Impaired cerebral autoregulation is frequent after severe traumatic head injury, and impaired CO2 reactivity may be associated with poor outcome.
To evaluate the incidence, asymmetry and relation to outcome of impaired autoregulation and CO2 reactivity.
Five patients with severe head injury were prospectively assessed in the first 24 hours after trauma for the presence of impaired autoregulation and CO2 reactivity. Four patients were monitored for invasive arterial blood pressure (ABP), intracranial pressure, cerebral perfusion pressure (CPP), jugular bulb oxymetry and transcranial Doppler (TCD) flow velocities and pulsatility index. One patient was monitored only for ABP and TCD parameters. Autoregulation was evaluated by flow velocity response to CPP and ABP changes induced by noradrenaline infusion. The CO2 reactivity was assessed by flow velocity response to ventilator manipulation of the minute volume. Outcome was assessed with Glasgow Outcome Scale at discharge from hospital and after 3 months.
Autoregulation was globally impaired in three of the five patients and impaired in one hemisphere in one patient. CO2 reactivity was globally impaired in one patient and impaired in one hemisphere in one patient. Three patients died, two of them probably associated with the severity of brain injury and one of septic shock. The two other patients are still in the hospital.
We present here a small series of patients, but the results suggest that impaired autoregulation is indeed common in these patients, which may have implications in therapy. We intend to increase our cohort and to correlate autoregulation and CO2 reactivity with outcome soon.