Ultrasound Guided Blockade of the Lumbar Plexus - the Supra Sacral Parallel Shift (SSPS)

Anesthesia for hip surgery can be performed with ultrasound guided blockade of the mesh of nerves (the lumbar plexus) supplying the hip region from the lumbar spinal nerves. This is a relevant technique in patients with severe cardiac comorbidity. The technique is a safer alternative compared to general or spinal anesthesia in these fragile patients. The most recognized technique with ultrasound guidance (Karmakars technique) is technically demanding and based on injection of local anesthetic relatively close to the exit of the spinal nerves from the spine. The risk is spread of local anesthetic to the spinal canal prompting a risk of low blood pressure. This may be fatal in high risk patients. The investigators have developed a simple technique based on injection away from the spinal canal. The investigators expect minimal risk of spread of local anesthetic to the spinal canal with this technique. This randomized, double blinded trial compares the new technique to the established technique of ultrasound guided blockade of the lumbar plexus. The hypothesis is that the new technique has a higher success rate with reduced effect on blood pressure for ultrasound guided lumbar plexus block compared to the established technique.

Lumbar plexus block guided by ultrasound and nerve stimulation with the patient in the lateral position and the probe in the parasagittal plane inserting the block needle between the transverse processes of L3 and L4 until an appropriate neuromuscular response is produced.

Lumbar plexus block guided by ultrasound and loss of resistance (LOR) with the patient in the lateral position and the probe in the parasagittal plane inserting the block needle between the transverse process of L5 and the sacral bone until an appropriate LOR is produced.

Inclusion Criteria: written informed consent ASA I (American Society of Anesthesiologists physical status classification) Exclusion Criteria: volunteers who are not able to cooperate volunteers who do not understand and speak danish daily use of analgesics allergy to local analgesics or contrast agents abuse of medicine or alcohol volunteers with technical impediments of the planned interventions