◊ PURPOSE:
Spinal anesthesia can be challenging in patients undergoing total joint arthroplasty because of poorly palpable surface landmarks and age-related changes in the lumbar spine. We hypothesized that pre-procedural ultrasound imaging would be effective in identifying the lumbar intervertebral spaces and would provide an accurate measure of the depth to the intrathecal space.
◊ METHODS:
Fifty patients undergoing elective total joint arthroplasty were recruited in this prospective descriptive study. Using a curved-array 2–5 MHz transducer, the lumbar spine was imaged in two views, i.e., longitudinal parasagittal (LP) and transverse midline (TM). The intervertebral levels were identified by counting upwards from the sacrum. The locations of the interlaminar spaces were identified by visualizing the ligamentum flavum–dura mater complex and the posterior aspect of the vertebral body. The needle insertion point for a midline approach was determined from the ultrasound examination and was marked on the skin of the patient’s back.
◊ RESULTS:
The mean patient age was 67 ± 10 yr, and 46% of the patients had a body mass index >30 kg · m−2. Surface landmarks were difficult or impossible to palpate in 38% of the patients. The scan quality on the LP and TM views was adequate or better in 100 and 98% of the patients, respectively. Dural puncture was achieved with one needle insertion attempt and within two needle insertion attempts in 84% and 98% of the patients, respectively. The ultrasound-measured depth to the intrathecal space correlated well with the actual needle insertion depth (concordance correlation coefficient = 0.82, accuracy 0.95, precision 0.86), with a tendency to overestimate the depth by just 2.1 ± 5.4 mm.
◊ CONCLUSIONS:
Ultrasound imaging of the lumbar spine provides clinically useful information that can facilitate spinal anesthesia in the older orthopedic patient population.
◊ Reviewed by C. Ecoffey
Professor and Chairman
Hôpital Pontchaillou, Université de Rennes, France
In previous studies, the knowledge of the distance between skin and epidural space and a preview of the spinal anatomy before puncture facilitated the epidural anesthesia procedure [1]. Many of the first descriptions of ultrasound imaging of the epidural space resulted from its use in parturients [2]. However, there is limited data on the potential role of ultrasound imaging of the spine in non-obstetric adult patients.
The results of this observational study of Chin and co-workers are consistent with the results of previous research in parturients. Ultrasonographic imaging of the intrathecal space may prove useful to complete the pre-puncture examination for spinal techniques and to facilitate the success of the puncture in the older orthopedic patient population. Despite the lack of a comparator group with a surface landmark-guided technique, one important point in this study was that pre-puncture ultrasound imaging accounted for a significant reduction in the number of puncture attempts and puncture sites. However, that only one practitioner has performed the study may limit reproducibility.
Although the routine use of ultrasound in central neuraxial blockade is probably unnecessary, this study confirmed its value in older and/or obese non-obstetric patients with poor surface landmarks, in particular in case of spine instrumentation [3] or spine deformation [4].
Due to the lack of a control group, definite conclusions cannot be drawn. However, the study is useful for guidance in clinical practice. Additional studies are warranted and indeed planned, especially in the field of real-time ultrasound control for intrathecal space cannulation.
◊ References:
[1] Grau T, Leipold RW, Conradi R et al. Ultrasound imaging facilitates localization of the epidural space during combined spinal– epidural anesthesia. Reg Anesth Pain Med 2001; 26:64 –7
[2] Grau T, Leipold RW, Horter J, et al. The lumbar epidural space in pregnancy: Visualization by ultrasonography. Br J Anaesth. 2001; 86: 798-804
[3] Chin KJ, Macfarlane AJ, Chan V, Brull R. The use of ultrasound to facilitate spinal anesthesia in a patient with previous lumbar laminectomy and fusion: a case report. J Clin Ultrasound 2009; 37: 482–5
[4] Chin KJ, Chan V. Ultrasonography as a preoperative assessment tool: predicting the feasibility of central neuraxial blockade. Anesth Analg. 2010; 110: 252-3
|
