Segmental Levels of Anaesthesia Following the Extradural Injection of 0.75% Bupivacaine at Different Lumbar Spaces in Elderly Patients

Abstract

Segmcntal anaesthesia levels were determined in 80 elderly patients following the eztraduial injection of 0.75% bupivacaine 15ml at four separate lumbar interspaces. Mean levels were Til intheL5-Sl group,T7 in the L4-5, T5 in L3-4 and T3 in the L2-3 group (P< 0.001). Varying the lumbar interspace at which the extradural anaesthesia is performed is recommended as a means of adjusting the levels of anaesthesia for different surgical procedures.Extradural anaesthesia via the caudal, lumbar or thoracic interspaces is associated with varying degrees of segmental spread. The most extensive spread results from thoracic injections, whereas more limited spread of anaesthesia is obtained when drugs are administered via the caudal route (Bromage, 1978). The present study attempted to determine whether injecting at different lumbar spaces produced varying degrees of spread and thus allowed the more accurate prediction of anaesthetic levels following extradural injection in the lumbar region. PATIENTS AND METHODSAge, height and weight were determined in 80 patients over 60 years of age undergoing lower abdominal or lower extremity surgery under extradural anaesthesia. All patients had an i.v. cannula inserted and received light premedication before the insertion of the extradural needle. Monitoring of arterial pressure and the ECG were performed routinely. Patients were not randomly allocated with respect to the site of surgery. For lower abdominal operations the local anaesthetic agent was injected via either the L2-3 space (group 1) or the L3-4 (group 2) space, and for procedures on the lower extremity, via the L4-5 (group 3) or the L5-S1 spaces (group 4).Extradural puncture was performed via a para- median approach with the operating table horizontal and the patient in the lateral decubirus position. The lumbar interspace was identified by examination and palpation of the lumbar spine, counting upward from the lumbo-sacral junction. Injections of 0.75% bupivacaine 15 ml (including a 3-ml test dose) were made at a rate of 1 ml s" 1 via a 17-gauge Tuohy needle with the bevel pointed cephalad. A catheter was inserted subsequently 1-2 cm into the extradural space and the patient then turned supine. After 30 min, the segmental level of anaesthesia was determined by the absence of pain to pinprick. It was not always feasible to examine the sacral dermatomes during surgery, but full sacral anaesthesia was observed in all patients at the end of the procedure. Consequently, for purposes of calculating the number of segments anaesthetized, it was assumed that all sacral dermatomes had been anaesthetized by 30 min. Statistical analysisComparisons of distributions of number of anaesthetized segments, age, weight/height 2 (Quetelet Index of Obesity) between the four sites of injection were carried out using the Kruskal-Wallis nonparametric test. Pairwise multiple comparisons were carried out using Duncan's multiple range test. RESULTSThe number of spinal segments anaesthetized was related significantly to the site of injection (P< 0.0...

Accuracy of Placement of Extradural Needles in the L3-4 Interspace: Comparison of Two Methods of Identifying L4

“…One study has shown that intradural analgesia may reach as high as Tl with injection at the L2-3 space, but only as high as T6 with injection at L4-5 [2]. Similarly, for extradural analgesia, injection at L2-3 gave a maximum block height of T3, while injection at L5-S1 caused the block to extend only as high as Til [3]. The authors of both these studies commented that the amount of haemodynamic instability was greater with injections made at a higher vertebral level.…”

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“…In addition to the neurologic consequences, the cephalad extent of sensory blockade is related to the level at which injection is performed. [3,4] In 1899, Jacoby described the line joining the top of the iliac crests as passing through the L4 vertebral body, and this observation has subsequently been verified multiple times. [5,6] It is speculated that, during pregnancy, the intercristal line is positioned higher than the L4 or L5 vertebral levels.…”

Comparing the minimum local anesthetic dose of ropivacaine in real-time ultrasound-guided spinal anesthesia and traditional landmark-guided spinal anesthesia: a randomized controlled trial of knee surgery patients

“…It is also well known that superiorly positioned SA will cause elevation of the plane block. Sharrock et al (24) administered SA at different intervertebral spaces with 15 mL of 0.75% isobaric bupivacaine and found that the mean levels were T11 when administered at L5-S1, T7 when administered at L4-5, T5 when administered at L3-4, and T3 when administered at L2-3. Taivainen et al (25) infused different doses of 0.5% isobaric bupivacaine in the L4-5 intervertebral space and found that 3 mL of 0.5% isobaric bupivacaine was able to achieve blockade at a mean level of T12 and that 4 mL and 5 mL of 0.5% isobaric bupivacaine were able to achieve blockade at a mean level of T10.…”