Continuous sedation during spinal anaesthesia: gamma-hydroxybutyrate vs. propofol

Gamma-hydroxybutyrate (GHB) may well be developed as an alternative for opt ional sedation during spinal anaesthesia. As in the case of propofol (PRO), GHB has good sedative properties associated with cardiovascular and respir atory stability. When used as a narcotic agent, recovery times are variable (e.g. > 30 min); in contrast, sedative dosages, as used in intensive care patients (e.g. 10-20 mg kg(-1) h(-1)), result in adequate clinical recovery . The goal of the present study was to compare the clinical properties of G HB and PRO after continuous administration during spinal anaesthesia (SPA). Thirty patients (ASA I and II) received either GHB (n=15) or PRO (n=15) at random. Patients refusing sedation (n=15) received 0.9% saline (control). At eight defined time points, haemodynamic (BP, HR), respiratory (RR, RMV, Pao(2), Spo(2), Peto(2), Petco(2), (V) over dot o(2), (V) over dot co(2)) a nd endocrinological parameters (plasma concentrations of noradrenaline and adrenaline) as well as the clinical side-effects were assessed simultaneous ly. With both sedatives, the desired level of sedation was achieved. Recove ry times ranged between 1.7 +/- 0.9 min with PRO and 6.1 +/- 4.9 min with G HB. GHB provided stable haemodynamic conditions without clinically relevant respiratory depression. In contrast, PRO caused a decrease in mean arteria l pressue (MAP) of 15%, whereas respiratory minute volume was decreased by 53% (with periods of apnoea, Spo(2)< 90%). (V) over dot o(2) and (V) over d ot co(2) correlated with respiratory minute volume (GHB, PRO, control). Pla sma noradrenaline and adrenaline concentrations remained nearly constant in the GHB and control groups and declined during sedation with PRO. Both GHB and PRO are suitable for optional sedation during spinal anaesthesia. Cont rol and recovery are acceptable for clinical purposes. It seems that GHB an d PRO have similar haemodynamic, respiratory and endocrinological character istics. Therefore, GHB may serve as an alternative for the established mana gement of continuous sedation during SPA with PRO.