Successful spinal anaesthesia depends on a reliable lumbar puncture technique. First establish venous access with a wide bore cannula and then position the patient either in the lateral position with the spine flexed maximally to open up the gaps between the vertebral spines or in the sitting position with the feet placed on a low stool at the side of the bed and the elbows resting on the thighs (Figure RA.7). Each position has drawbacks and advantages and the choice is usually made on personal preference. In either case, a skilled assistant is necessary to position the patient correctly, maintain and support the posture and establish a rapport with them during the conduct of the block.
Figure RA.7 Patient positions for spinal anaesthesia
A line joining both iliac crests (Tuffier's line) passes across the spine of L4 and is a reliable landmark for locating the L3/4 interspace which is usually easily defined and is the one most often used. The technique for spinal anaesthesia is described in Figure RA.8.
Note that 22 G needles are robust enough to be used in patients with calcified ligaments or other anatomical difficulties and are recommended for elderly patients where these problems are more common and the risk of PDPH is very low. If an introducer is required, it should be inserted into the deep layers of the interspinous ligament, so that the needle has only a short distance to travel. Narrow gauge needles may be deviate or be damaged by the ligamentum flavum, calcified ligaments or osteophytes and also will give little feedback. After performing the block the blood pressure, pulse rate and ECG should be monitored as the onset of sympathetic nerve blockade is quite rapid.
Was this article helpful?
This guide will help millions of people understand this condition so that they can take control of their lives and make informed decisions. The ebook covers information on a vast number of different types of neuropathy. In addition, it will be a useful resource for their families, caregivers, and health care providers.