Dose and Concentration Relationship for PENG Block in Hip Surgery

A number of peripheral nerve blocks are routinely performed in patients who will undergo orthopedic hip surgery for pain relief. Proximal extensor group nerve (PENG) block is one such field block which is used for this purpose and could be performed both before and after the operation. When used before surgery, PENG block is reported to be beneficial in alleviating pain during positioning for spinal anesthesia. Furthermore, some studies suggest a high volume block may increase the analgesic effect of the block. In this perspective, this study aims to observe the effects of different volumes of local anesthetic (bupivacaine) at the same dose used for PENG block in hip fracture positioning for spinal anesthesia.

The investigator hypothesizes that a high volume (\>20ml) PENG block will reduce pain during positioning compared to a low volume PENG block.

This prospective observational study will be conducted between 04.07.2022-04.01.2023 in the orthopedic operating rooms of T.C. Ministry of Health University of Health Sciences Prof. Dr. Cemil Taşçıoğlu City Hospital. Patients over the age of 18 who are scheduled for hip fracture under spinal anesthesia meeting the inclusion criteria and who agree to participate in the study by signing a consent form will be included. Patients will be surveyed about the amount of pain they suffer with numerical rating scale (NRS) four times; firstly, 15 minutes after the block at rest, then, a second time with a 10 degree hip flexion, after that a third time when patient is given sitting position for spinal anesthesia, and lastly, 24 hours after the surgery. Age, height, weight, gender, co-morbidities, American Society of Anesthesiologists physical condition (ASA) scores, time of block administration, whether an intraoperative complication developed (hypotension, tachycardia, bradycardia, inotropic need, desaturation), local anesthetic (bupivacaine) volume used for PENG block will be recorded from the anesthesia charts. Twenty-four hours after the surgery patients will be questioned for nausea, vomiting and urinary retention. At this point the 4 A's test (4AT) will be performed to detect any presence of delirium. Postoperative iv analgesic treatments and mobilization times(if mobilized) of the patients will be recorded from patient charts. Resulting data for low volume (less than or equal to 20ml) and high volume PENG blocks will be compared.

It is expected that a total of 112 patients will be recruited for this study. A power analysis revealed that it is necessary to recruit at least 102 patients, when effect size d is assumed to be 0.5 ( for medium difference) for a 0.05 alpha error with a %80 power. Taking in account a 10% follow-up loss we planned to recruit 112 patients.

Eligibility Criteria:
Inclusion Criteria:

* Patients over the age of 18 who consent to participate and;
* Patients who are scheduled for hip surgery under spinal anaesthesia,
* Patients who have no neurocognitive disorders that impair cooperation and communication (e.g Alzheimer's disease, Parkinson's disease, senile dementia),
* Patients who have no local anaesthetic allergies,
* Patients to whom an analgesic PENG block was administered preoperatively to facilitate sitting position during spinal anaesthesia will be included.

Exclusion Criteria:

* Patients under the age of 18,
* Patients who decline to participate,
* Patients who are scheduled for hip surgery under general anaesthesia
* Patients who have neurocognitive disorders
* Patients who have local anaesthetic allergies
* Patients to whom an analgesic PENG block was NOT administered preoperatively to facilitate sitting position during spinal anaesthesia will be excluded.