Does a mid-lumbar block level provide adequate anaesthesia for transurethral prostatectomy?

ABSTRACT

In this prospective, randomized study, 23 patients having spinal anaesthesia for transurethral prostatectomy (TURP) were evaluated for the adequacy of their block using a visual analog pain score (VAPS). Each patient with a "standard" (> or = T10) block level (n = 5) or "intermediate" (L1 or T12) block level (n = 5) found the block adequate. Sixty-two percent (8/13) of patients with a "low" (< or = L3) block level found their block adequate. The VAPS was assessed every five minutes or whenever pain abruptly increased during TURP; an "inadequate block" was defined as a VAPS > or = 5/10 during prostatic resection. Intravesical pressure was monitored and kept < 15 mmHg to distinguish between pain from bladder distension and from prostatic resection. "Low" block patients (LBP) who found their block inadequate (n = 5) received supplemental intrathecal local anaesthetic given through a spinal catheter. The subsequent L1 block level was adequate for TURP. In LBP, who found their block adequate (n = 8), a higher (P < 0.01) VAPS was observed than in patients with a "standard" block level. However, a smaller (P < 0.05) maximum percent decrease in diastolic blood pressure was found in LBPs, than in "intermediate" or "standard" block patients. It is concluded that a spinal block > or = L1 is adequate during TURP when bladder pressure is monitored and kept low. Mid-lumbar block levels should be reserved for patients in whom the benefit of minimizing haemodynamic changes outweighs the risk of a "less complete" anaesthetic.