The Effectiveness of Pre-puncture Lumbar Spine Ultrasound Scanning in Spinal Anaesthesia for Caesarean Section

Abstract

Spinal anaesthesia is commonly used as a method of regional anaesthesia for surgeries below the level of the umbilicus. It is a safe substitute to general anaesthesia. It has been in existence since late in the 19th century. It is easy to learn the technique and needs lower amounts of local anaesthetics. This has made it a popular method of regional anaesthesia. Identification of the puncture site is accomplished by either palpation or by pre-puncture ultrasound guidance. The palpation method uses the tuffier’s line to determine the spinal level. This has been shown to be inaccurate in previous studies. Patients with difficult to palpate landmarks pose a challenge to the anaesthesia care provider which in turn may lead to increased number of puncture attempts and patient discomfort. Pre-puncture lumbar spine ultrasound allows the anaesthesia care giver to identify the midline, intervertebral space and subarachnoid space depth before performing lumbar puncture for spinal anaesthesia. Study Objective To determinethe effectiveness of pre-puncture lumbar spine ultrasound as a guide to performing spinal anaesthesia in obstetric patients. Materials and methods Study design: This was a prospective descriptive observational study exploring lumbar spine ultrasound as a guide to spinal anaesthesia for obstetric patients. Ultrasound had been used before to guide spinal anaesthesia in patients with difficult landmarks and those in whom the palpation method completely failed. Study site: The study was conducted in KNH and Naivasha level 5 maternity theatres. Methodology: Patients selected for the study underwent a pre-puncture lumbar spine u/s that identified the L3/4 and L4/5 vertebral levels, the midline and the skin to subarachnoid space depth was measured. These guided performance of the lumbar puncture for spinal anaesthesia. Data collection and analysis Data collected included number of successful punctures, number of attempts and redirections, traumatic punctures and skin to subarachnoid space distance. Data was entered and analysed with the use of IBM SPSS version 21.0. Clinical measurements were presented as means and standard deviation, and where applicable median values. Proportion of successful LPs following ultrasound was presented as a percentage. xii Results There was a 92.2% success rate in lumbar punctures following lumbar spine ultrasound. The first attempt success rate was 71.6%. The tuffier’s line was found to cross at the L3 vertebral level in the majority of the patients (65.6%) with a total of 93.3% having it crossing above the L4 vertebral level. Only 2 patients (2.2%) experienced paraesthesia during puncture and no bloody attempts were reported. There was a statistical difference between ED-US and ED-N in this study (p= 0.397). Outcome measures This study showed the usefulness of ultrasound in identification of ideal puncture site for spinal anaesthesia while describing the pattern of traumatic punctures and level of satisfaction experienced by the patient.