Geriatric patients have a significantly higher incidence of morbidity and morality during surgery compared with younger age group as they commonly have respiratory, circulatory and renal problems \[1\]. Transurethral resection of the prostate (TURP) is the gold standard treatment for elderly patients with bladder outlet obstruction. TURP procedure has been associated with high morbidity rate including bleeding, TURP syndrome, bladder perforation, hypothermia and disseminated intravascular coagulation during intraoperative and early postoperative period. Therefore, it becomes very important to keep a stable anesthesia that minimizes these side effects. Detection of such complications is quite difficult under general anesthesia as compared to regional anesthesia. Thus Regional techniques may be better tolerated in the elderly patients undergoing TURP having the advantages of minimizing blood loss and thromboembolic events \[2\].

Subarachnoid single dose injection provides a potent blockade of fast onset while its extension and duration are difficult to predict \[3\]. Continuous epidural anesthesia with a catheter placement offers flexibility to extend, intensify, and maintain the block as well as providing postoperative analgesia \[4\]. Continuous spinal anesthesia consists of introducing a catheter in the subarachnoid space and maintaining blockade by repeated anesthetic injections. The possibility of fractionating local anesthetics dosage along time allows a fast onset with better blockade quality and less hemodynamic changes \[5\]. Recent study \[6\] reported that pain scores in patients received continuous spinal anesthesia were significantly lower than those received continuous femoral nerve block.

Advantages of continuous spinal anesthesia include the following: (a) Prior placement of the catheter in the induction area facilitates the surgical schedule. (b) Spinal anesthesia may be induced through the catheter after the patient has been positioned for surgery, thereby lessening the potential for hypotension. (c) The low doses of local anesthetic intermittently injected eliminate the possibility of systemic toxic reactions. (d) Repeated injection of small doses of local anesthetic solution facilitates obtaining the right level of anesthesia and decreases the cardiovascular instability during induction. (e) Employing a low dose of local anesthetic shortens the recovery period. (f) Anesthesia can be prolonged when the duration of surgery is uncertain. (g) A definite end point (aspiration of cerebrospinal fluid) assures that the catheter is in the right place and so enhances the likelihood of successful anesthesia. (h) Subarachnoid narcotics may be administered during a surgical procedure or continued into the recovery period to provide long-lasting postoperative analgesia \[7\].

The disadvantages of continuous spinal anesthesia are as follows: (a) Additional time is required to place the catheter in the right place, which may occasionally prove difficult. (b) Spinal headache is possible. (c) There is a potential for catheter breakage, infection, nerve trauma, and hemorrhage (these potential complications have, however, rarely been documented in previous clinical settings). The primary factor that has limited use of continuous spinal anesthesia is the belief that the large size of available spinal catheters requiring insertion through large spinal needles will result in an incidence of post dural puncture headache (PDPH) in young patients that is unacceptable \[7\].

The Wiley Spinal™ (Epimed; Johnstown, NY) catheter is an innovative flexible cannula over needle designed for convenient intrathecal access that reduces PDPH \[8\]. We hypothesized that using less anesthetics during continuous spinal anesthesia with the Wiley spinal catheter would offer more hemodynamic stability with less side effects when compared with continuous epidural anesthesia in patients undergoing TURP. The primary outcome of this study is the hemodynamic variability between both techniques. Secondary outcomes of interest are detection of adverse events including early and late neurological complications. Thus the aim of this prospective randomized study is to compare the efficacy of the continuous spinal anesthesia using the Wiley spinal catheter and continuous epidural anesthesia in geriatric patients undergoing TURP.