Erector Spine Block in Patients Undergoing Back Surgery, Observational Feasibility Trial of the Effect on Postoperative Pain-scores and Opioid Consumption

In 10-15 patients undergoing back surgery (laminectomy or back surgery with lumbar pedicle screw placement or revision back surgery), will be asked to give informed consent to receive a bilateral lumbar erector spinae block before surgery. In this population it will be clear after 10-15 patients if there is a beneficial effect since these patients normally require a substantial amount of postoperative opioids because of significant postoperative pain.

The blocks will be performed by experts in the field of ultrasound guided locoregional anaesthesia in a separate block room with ultrasound after placement of an iv line and application of standard monitoring (ECG, NIBP, saturation)

Description of block performance according to Chinn et al but at a lumbar level:

The patient will be placed in the lateral or sitting position. With a curve array probe or a high frequency linear probe, depending on the BMI of the patient, will be placed in a longitudinal position 2-3 cm lateral of the vertebral column. The transverse processes of the vertebrae at the (mid) level of surgery, the erector spinae muscle and the psoas muscle are identified. Depending on the depth a 5 or 8 cm 22 G ultrasound needle (pajunk) will be inserted in an in plane technique in a cephalad to caudad direction until bone contact with the top of the transverse process is reached. After slight retraction of the needle, 20 ml of ropivacaine 0,375% will be injected behind the erector spinae muscle. The same procedure will be repeated on the contralateral side.

Sensory loss of the posterior dermatomes and dermatomes of the anterior roots of the spinal nerves (lumbar plexus, upper leg) will be tested Motor function of the legs will be evaluated with a Bromage (0-3) score.