Objective: To study the effects of preoperative phenoxybenzamine (o.p) on preventing epidural-morphine-induced urinary retention and effects of neostigmine on releasing it.
Methods: 80 patients who received epidural morphine to release postoperative pain were divided into 4 groups randomly and received preoperative phenoxybenzamine (group P, n = 20), neostigmine (i. m) when urinary retention happened (group N, n = 20), both drugs (group U, n = 20), and without drugs (Control, n = 20), respectively. The incidences of urinary retention and release were observed.
Results: No significant decrease (P > 0.05) happened after operation in the incidence of epidural-morphine-induced urinary retention both in the group P and in the group N. Neostigmine(i. m) could significantly release (P < 0.001) the epidural-morphine-induced urinary retention when phenoxybenzamine was administrated preoperatively.
Conclusion: Preoperative phenoxybenzamine can not prevent epidural-morphine-induced urinary retention. Neostigmine can release the urinary retention only when preoperative phenoxybenzamine is used.