Epidural placement: lateral position
Advanced, Clinical Subspecialties
Patient positioning during initiation of epidural blockade does not appear to affect the resultant spread of analgesia or anesthesia. The patient may be placed in either the lateral or sitting position. The midline of the spine is easier to palpate when the patient is sitting, especially in the obese patient, therefore making the nerve block technically easier. Whether the patient is in the sitting or the lateral position, there is no significant difference in nerve block height. It has been suggested in a study by Seow and associates that there is slightly faster onset time, duration, and density of motor nerve block on the dependent side when the epidural is placed with the patient in the lateral position.
The lateral decubitus position may be more appropriate for patients who cannot comfortably assume the sitting position. Additional benefits include the following: Sedation can be used more liberally; vagal reflexes can be minimized; hemodynamic changes may be better tolerated; there may be less need for a well-trained assistant to help maintain positioning; and there appears to be a reduced incidence of unintentional epidural vein cannulation and dural puncture. Finally, in the case of CSEs with hyperbaric LAs, unilateral nerve blocks for certain orthopedic procedures may be more easily attained in the lateral position.
The left lateral recumbent position may be preferable for right handed physicians and may provide improved hemodynamic stability for parturients. The coronal plane of the patient should be perpendicular to the floor, with the tips of the spinous processes pointing toward the wall. The thighs should be flexed toward the abdomen and the knees drawn to the chest; the neck should be in a neutral position or flexed so that the chin rests on the chest. Asking the patient to “assume the fetal position” may help maximally flex the spine. The hips should be aligned one above the other, and the nondependent arm should extend toward and rest on the nondependent hip. The patient’s head may need to be elevated with a pillow to avoid rotation of the spine. Obese patients or those with larger hips may require additional pillows to maintain proper alignment. Directing the needle toward an imaginary line that extends cephalad and caudad from umbilicus may optimize chances of midline insertion.