ORIGINAL ARTICLE The effect of injection speed on the spinal block characteristics of hyperbaric bupivacaine 0.5% in the elderly Smita Prakash • Veena Bhartiya • Vedatrayee Pramanik • Jyoti Pahilajani • Anoop Raj Gogia • Rajvir Singh Received: 16 January 2010 / Accepted: 24 September 2010 / Published online: 26 October 2010 Ó Japanese Society of Anesthesiologists 2010 Abstract Purpose The purpose of this prospective, randomized, double-blind study was to compare anesthetic characteris- tics after two speeds of intrathecal injection of hyperbaric bupivacaine in elderly patients. Methods Fifty-six patients, aged C65 years, undergoing transurethral surgery under spinal anesthesia were allo- cated randomly to two groups according to rate of intra- thecal injection of 2 ml hyperbaric bupivacaine 0.5%: group Fast (maximum possible rate; mean 0.38 ml/s) n = 26; group Slow (over 40 s; 0.05 ml/s), n = 25. Spinal blocks were administered in the lateral position. Data collection at different times included sensory level, motor block, hemodynamic changes, and occurrence of neuro- logical symptoms. Results There was no significant difference between the groups regarding maximum sensory anesthetic level achieved (group Fast: T7 (T4–T10), median (range); group Slow T8 (T6–T10), P = 0.184); times (min) to reach (a) T10 sensory level (group Fast 5.3 ± 4.2 (mean ± SD), group Slow 8.0 ± 6.5, P = 0.093); (b) maximum sensory level (group Fast 11.6 ± 4.7; group Slow 13.6 ± 6.1, P = 0.199); and (c) 2-segment regression of anesthesia (group Fast 92.2 ± 29.6; group Slow 104.7 ± 36.1, P = 0.182). Degree and duration of motor block were similar (P = 0.947 and P = 0.895, respectively). Hemodynamic changes, ephedrine and atropine requirement, incidence of postoperative neurological symptoms after 24 h and 1 week were similar (all P [ 0.05). Conclusions An eightfold difference in speed of intra- thecal injection of 0.5% hyperbaric bupivacaine did not affect the clinical characteristics of spinal anesthesia in elderly patients undergoing transurethral surgery. Keywords Anesthetic techniques Á Spinal Á Speed of injection Á Anesthetics Á Local Á Bupivacaine Introduction The effect of speed of injection of local anesthetic solution on the anesthetic characteristics of spinal anesthesia remains controversial. The literature is replete with inves- tigations using isobaric local anesthetic solutions [1–7]. However, data with regard to effect of injection speed using hyperbaric solutions for spinal block are limited [8–11]. Most studies using hyperbaric solutions of local anesthetics have not shown a difference in anesthetic pro- file [8–10], although a higher spread of sensory block with slow rate of injection has been reported [11]. Patient age and the volume of cerebrospinal fluid (CSF) affect the distribution of local anesthetic solution in the CSF [12]. Cameron et al. [13] suggested that a low CSF volume could explain the increase in spread of spinal anesthesia in the elderly. If CSF volume decreases with age, speed of injection of local anesthetic solution, would, perhaps have a greater effect on the spread of anesthesia in the elderly. Although baricity of the solution injected and S. Prakash Á V. Bhartiya Á V. Pramanik Á J. Pahilajani Á A. R. Gogia Department of Anesthesia and Intensive Care, Vardhman Mahavir Medical College and Safdarjang Hospital, New Delhi 110029, India R. Singh Medical Research Centre, HMC, Doha, Qatar S. Prakash (&) C 17 HUDCO Place, New Delhi 110049, India e-mail: drsunilprakash@gmail.com 123 J Anesth (2010) 24:877–881 DOI 10.1007/s00540-010-1035-x