Satisfactory spinal anesthesia with a total of 1.5 mg of bupivacaine for transurethral resection of bladder tumor in an elderly patient

Spinal anesthesia is the most frequently used anesthetic technique for endoscopic urological surgery because the signs and symptoms of water intoxication with fluid overload can be recognized earlier. However, many patients undergoing urological surgery are elderly and have coexisting cardiac and pulmonary disease. It is therefore important to limit the distribution of spinal block to reduce adverse hemodynamic and pulmonary effects in such patients [3, 4].

Baydilek et al. [5] compared continuous spinal anesthesia (CSA) with single-dose spinal anesthesia (SDSA) in geriatric patients undergoing transurethral resection of prostate. In their group SDSA, 2.5 ml of 0.5 % levobupivacaine (12.5 mg) was injected through the spinal needle and in their Group CSA, initially 2 ml of 0.25 % levobupivacaine (5 mg) was injected through the intrathecal catheter. If the level of sensory block had not reached T10, an extra 1 ml of 0.25 % levobupivacaine (2.5 mg) was given through the catheter, this was repeated until T10 block level was reached. The mean effective dose in Group CSA was (8.70 ± 1.63) mg. They found that CSA provided better hemodynamic stability, shorter recovery period and equal anesthetic quality. Similar findings to the study of Baydilek et al. were reported by others with spinal anesthesia for orthopedic lower extremity surgery [6–11], but none of them diluted the local anesthetic solution.

Concentration of local anesthetic in cerebrospinal fluid (CSF) is one of the factors affecting uptake of local anesthetic into neural tissue [1, 2]. We diluted local anesthetic solution to attenuate the intensity of neural blockade.

Density of CSF at 37 °C ranges from 0.9998 g/ml to 1.005 g/ml varying with reports [2, 12–16]. Specific gravity of 0.5 % hyperbaric bupivacaine solution at 20 °C is 1.025–1.031 (AstraZeneca Pharmaceutical Company). Density of normal saline at 20 °C is 1.004 g/ml, and that of distilled water at 20 °C is 0.9982 g/ml (Otsuka Pharmaceutical Company). Calculated density of our diluted 0.1 % solution at 20 °C is 1.0078–1.009 mg/ml. Increasing temperature decreases the density of a solution [1, 2]. Our diluted 0.1 % solution would have been warmed up to patient’s CSF temperature and the density would have been less than 1.0078–1.009 mg/ml. In fact, our diluted anesthetic solution worked as an approximately isobaric solution.

One of the most serious complications of spinal anesthesia is cardiac arrest [17–19]. The cardiologist suggested the possibility of cardiac arrest in this case. Unnecessary high level of spinal anesthesia-induced sympathetic blockade should be avoided. The spread of SDSA is reported to be unpredictable [2]. However, our method, incremental administration of diluted local anesthetic solution, made it possible not only to predict but also to control the spread of local anesthetic.

Many articles suggest that the addition of fentanyl or sufentanil can enhance local anesthesia and thereby reduce the dose of local anesthetics with more stable hemodynamics for urological surgery [3, 20, 21] and other surgery [11, 22–26]. Had we added fentanyl to bupivacaine, it might have reduced the dose of bupivacaine and provided more stable hemodynamics and the need for vasopressors.