EFFECTS OF DESFLURANE ON CEREBRAL BLOOD-F LOW VELOCITIES AND CEREBROVASCULAR CO2 REACTIVITY IN CHILDREN

Objective: To assess in children with a transcranial Doppler the effec t on cerebral blood flow velocities of desflurane, whose cerebral vaso dilator effects have been studied in animals and in adults with intrac ranial lesions. Study design: Prospective clinical study. Patients: Te n healthy children, mean age: 3.4 yr, ASA physical class 1, undergoing minor urologic surgery, were included in this study. Method: Inductio n was obtained with atropine 10 mu g . kg(-1), fentanyl 3 mu g . kg(-1 ) and propofol 3 mg . kg(-1). Endotracheal intubation was facilitated by atracurium 0.3 mg . kg(-1). Mechanical ventilation, with a 50% air/ oxygen mixture was adjusted to achieve an end-tidal CO2 (PETCO2) level of 38 +/- 2 mmHg. Monitoring included measurement of mean arterial bl ood pressure (MAP), heart rate, PETCO2, SpO(2) and end-tidal desfluran e concentrations (FETDes). Mean blood flow velocities (Vmean) were mea sured in the middle cerebral artery using a bi-directional 2 MHz TCD s ystem (EME - TC 2000 S). A first TCD measurement followed intubation ( T1). Thereafter, desflurane was adjusted to 1 MAC. Six other TCDs were recorded each minute until FETDes reached the inspired fraction (T2-T 7). Thereafter, CO2 reactivity was assessed with a hypocapnia test, in duced by hyperventilation. Measures were done at T8 (PETCO2: 33 +/- 1 mmHg), T9 (PETCO2: 29 +/- 1 mmHg), and T10 (initial PETCO2: 38 +/- 1 m mHg). All these measurements were made before starting surgery. Analys is of variance (ANOVA) was used to analyse the data (P < 0.05 was cons idered as significant). Results: The Vmean and heart rate increased si gnificantly with increasing concentrations of desflurane (Vmean from 6 8 +/- 27 to 106 +/- 30 cm . s(-1) and heart rate from 109 +/- 17 to 13 6 +/- 15 b . min(-1) between T1 and T7). During hypocapnia, Vmean decr eased to 68 +/- 23 cm . s(-1) at T9, and returned to normal values wit h PETCO2 at 38 mmHg at T10. SpO(2) remained unchanged. Mean arterial p ressure was stable from T1 to T7, but decreased significantly at T9 an d T10. Conclusion: Desflurane elicits a dose-dependent increase in cer ebral blood flow velocities and heart rate, but does not change mean a rterial pressure, suggesting that its cerebrovascular action is indepe ndent of its systemic vascular action. CO2 reactivity is maintained at one MAC. The results in children are similar to those seen in adults. (C) 1998 Elsevier, Paris.