[Relationship between dexmedetomidine continuous infusion and end-tidal sevoflurane concentration, monitored by bispectral analysis.].
OBJECTIVE
General inhalational anesthesia associated with intravenous agents provides analgesia and hypnosis of better quality. Dexmedetomidine is a specific a2-adrenergic agonist with these characteristics and is known by providing hemodynamic stability. This study aimed at evaluating the effects of dexmedetomidine continuous infusion on end-tidal sevoflurane concentration (ETsevo) in general anesthesia, monitored by EEG spectral index (BIS).


METHODS
Participated in this prospective study 24 adult patients of both genders, physical status ASA I and II submitted to elective surgery under general anesthesia and monitored by ECG, BP, SpO2, P ET CO2, ETsevo and BIS. Intravenous anesthesia was induced with alfentanil (30 microg.kg-1), thiopental (5 mg.kg-1) and vecuronium (0.1 mg.kg-1), followed by tracheal intubation. Then, sevoflurane (to maintain BIS between 40 and 60), controlled ventilation with tidal volume of 10 mL.kg-1 and P ET CO2 between 35 and 45 mmHg were started. During maintenance, 60 minutes after anesthetic induction (T60), continuous dexmedetomidine infusion was started in 2 phases: initial infusion (1 microg.kg-1) in 20 minutes; and maintenance infusion (0.5 microg.kg-1.h-1). Sevoflurane concentration was adjusted to maintain BIS between 40 and 60. BP, HR, ETsevo, SpO2, P ET CO2 and BIS were evaluated in the following moments before anesthetic induction (M-15), M15, M45, M75, M105 and M120.


RESULTS
The association of dexmedetomidine to general anesthesia with sevoflurane provided statistically significant ETsevo decrease (p < 0.05) from M45 (1.604 +/- 0.485) to M105 (1.073 +/- 0.457), and from M45 (1.604 +/- 0.485) to M120 (1.159 +/- 0.475). Hemodynamic parameters have shown statistically significant differences (p < 0.05), however without clinical repercussions.


CONCLUSIONS
The association of dexmedetomidine continuous infusion (0,5 microg.kg-1.h-1) to inhalational anesthesia with sevoflurane provided end-tidal sevoflurane concentration decrease while maintaining hemodynamic stability.
Magalhães
Edno
E
Faculdade de Medicina, Universidade de Brasília.
Govêia
Cátia Sousa
CS
Ladeira
Luís Cláudio de Araújo
LC
Espíndola
Beatriz Vieira
BV