The effect of calcium channel blockers on cerebral oxygenation during tracheal extubation

Calcium channel blockers are effective in stabilizing systemic hemodynamics during tracheal extubation. However, they may increase cerebral blood flow (CBF) during tracheal extubation because of cerebral vasodilation, even if systemic arterial blood pressure decreases. In this study, we observed cha nges in cerebral oxygenation during tracheal extubation by using near-infra red spectroscopy and evaluated the effect of nicardipine and diltiazem on t he resultant changes. We studied 45 women undergoing elective gynecologic s urgery. After surgery, the patients were randomly allocated to three groups (n = 15 each): saline (control), 0.02 mg/kg nicardipine, and 0.2 mg/kg dil tiazem. After 2 min, we started to aspirate secretions for 2 min and then, extubated the trachea. Changes in cerebral oxygenated hemoglobin (Hbo(2)) a nd deoxygenated hemoglobin were measured during the extubation procedure fo r 9 min after drug treatment. Systemic hemodynamics, including mean arteria l blood pressure, heart rate, end-tidal Co-2, end-tidal sevoflurane concent ration, and peripheral arterial oxygen saturation were also monitored. Duri ng extubation, Hbo(2) increased significantly, presumably caused by the inc rease in CBF. Changes in deoxygenated hemoglobin were minimal. Compared wit h the control, nicardipine and diltiazem significantly inhibited the increa se in mean arterial blood pressure. On the contrary, they significantly enh anced the increase in Hbo(2). In conclusion, calcium channel blockers may i ncrease CBF during extubation, even if these drugs stabilize systemic hemod ynamics.