Changes in Intracerebral Environment During Induction of Anesthesia

Background: Although marked hemodynamic changes do not generally occur during induction of general anesthesia with intravenous anesthetics, the effects of such hemodynamic changes on the intracerebral environment are not well known. We used a near-infrared oxygenation monitor to compare the effects of two intravenous anesthetics on the intracerebral environment. Material and Methods: We investigated the effects of propofol and thiopental in adult patients according to age and the presence or absence of hypertension. The patients were divided into four groups: propofol in adult patients (PF group), thiopental in adult patients (TP group), thiopental in elder patients (TPE group), and thiopental in elder patients with hypertension (TPEH group). We measured the noninvasive blood pressure, pulse rate, oxyhemoglobin (oxy-Hb) level, deoxyhemoglobin (deoxy-Hb) level, and total hemoglobin (total-Hb) level in all patients. Results: The maximum oxy-Hb level occurred 2.5 min after spreading the larynx to spray with lidocaine in the PF, TP, and TPE groups (5.1 ± 3.0, 6.8 ± 2.8, and 7.1 ± 2.8 nmol/L, respectively). The minimum deoxy-Hb level occurred 2.5 min after spreading the larynx in the PF group (？1.9 ± 1.8 nmol/L), 2.5 min after intubation in the TP group (？2.6 ± 3.0 nmol/L), and immediately after intubation in the TPE and TPEH groups (？3.9 ± 2.9 and ？1.9 ± 1.4 nmol/L, respectively). The maximum total-Hb level occurred 2.5 min after spreading the larynx in the PF group (1.9 ± 5.0 nmol/L), immediately after intubation in the TP group (2.3 ± 3.1 nmol/L), 2.5 min after spreading the larynx in the TPE group (3.7 ± 3.6 nmol/L), and 2.5 min after intubation in in the TPEH group (6.7 ± 5.2 nmol/L). Conclusion: Intravenous anesthetics and changes in blood pressure influence the intracerebral environment during induction of anesthesia