To investigate the role of orexin-A in doxapram-induced promotion of emergence from general anesthesia in patients.

Forty-four patients of both sexes, aged 18-60 yr, with body mass index of 21-25 kg/m², of American Society of Anesthesiology physical status Ⅰ or Ⅱ, scheduled for elective lumbar surgery under general anesthesia, were divided into 2 groups (n=22 each) using a random number table: control group and doxapram group.Anesthesia was induced by intravenously injecting propofol, sufentanil and cisatracurium.The patients were mechanically ventilated after tracheal intubation.Anesthesia was maintained by inhaling sevoflurane and target-controlled infusion of remifentanil.Sevoflurane inhalation and remifentanil infusion were stopped at the end of operation, oxygen flow rate was adjusted to 6 L/min, doxapram 0.5 mg/kg were intravenously injected at the same time in doxapram group, and the equal volume of normal saline was given in control group.The emergence time and extubation time were recorded.On admission to operating room (T₀), at 1 h after anesthesia induction (T₁) and 5 and 30 min after tracheal extubation (T_{2, 3}), arterial blood samples were collected for determination of blood glucose concentrations and plasma orexin-A concentrations (by radioimmunoassay).

Compared with the baseline at T₀, blood glucose concentrations were significantly decreased at T₁ and increased at T₃, and plasma orexin-A concentrations were increased at T₂ in two groups (P<0.05). Compared with control group, the time to eye opening and extubation time were significantly shortened, plasma orexin-A concentrations were increased at T₂ (P<0.05), and no significant change was found in blood glucose concentrations at each time point in doxapram group (P>0.05).

The mechanism by which doxapram promotes emergence from general anesthesia may be related to increasing plasma orexin-A concentrations in patients.

Doxapram; Anesthesia, general; Emergence; Orexin