Cerebrovascular carbon dioxide reactivity with propofol anesthesia in patients with previous stroke.

STUDY OBJECTIVE

To examine whether patients with previous stroke have impaired cerebrovascular carbon dioxide (CO2) reactivity when receiving propofol anesthesia.

DESIGN

Prospective, controlled study.

SETTING

University hospital.

PATIENTS

34 consecutive patients, 17 of whom had previous stroke and were scheduled for elective cardiac surgery, and 17 control age-matched patients without previous stroke who were also scheduled for cardiac surgery.

INTERVENTIONS

Anesthesia was induced and a 2.5-MHz pulsed transcranial Doppler probe was attached to the patient's head at the right temporal window. Mean blood flow velocity of the middle cerebral artery (Vmca) was measured continuously.

MEASUREMENTS

After establishing baseline Vmca, arterial blood gases and cardiovascular hemodynamic values, partial pressure of end-tidal CO2 (PETCO2) was increased by changing the ventilatory frequency by 2 to 5 breaths/min. The measurements were repeated when PETCO2 increased and remained stable for 5 to 10 minutes.

MAIN RESULTS

Values for absolute CO2 reactivity in the control patients and in those with previous stroke were 2.6 +/- 0.5 and 2.9 +/- 0.7 cm/sec/mmHg, respectively, a nonsignificant difference in these values. Values for relative CO2 reactivity in control patients and in patients with previous stroke were 6.4 +/- 1.4 and 6.1 +/- 1.4%/mmHg, respectively, with no significant difference noted.

CONCLUSIONS

Cerebrovascular CO2 reactivity in patients with previous stroke is normal during propofol anesthesia.