After the approval of ethics committee of Ain Shams University, number FMASU R 10 / 2018, this study was registered in ClinicalTrials.gov : NCT03450798 and carried out according to the Consolidated Standards of Reporting Trials (CONSORT) 2010 statement .This prospective randomized double blinded parallel group study was conducted over 107 patients between the age of 35–57 years old, American Association of Anesthesiologists (ASA) physical status I and II, scheduled for fixation of open tibial fractures using Ilizarov external fixator. This study was carried out at Ain Shams University hospitals from February 2018 to January 2019. Initially written informed consent was signed by all patients.
Patients unable to communicate with the investigators or hospital staff, morbidly obese patients (body mass index>40 kg/m2), patients undergoing bilateral surgery, patients with coagulopathies, renal insufficiency (creatinine>1.5 mg/dl), American Society of Anesthesiologists III-IV, contraindications to regional anesthesia, patients with unstable vital data and patients with head or chest trauma were excluded from the study.
Pre-anesthetic check, full history and routine investigations were done before the surgery.
After an intravenous (IV) cannula was secured, and midazolam 0.05 mg/kg IV was given to all patients before transfer to the operating room. Standard monitoring devices as ECG, non- invasive blood pressure and pulse oximetry were placed. Then, patients were randomly allocated by sealed envelope technique done according to the randomization schedule, prepared and opened by a resident not involved in any part of the study to receive either spinal anesthesia or SOFT block, the clinician responsible for data collection and patients’ follow-up were blinded to the patients’ grouping. A single experienced operator had performed all blocks and spinal anaesthesia did not participate in the study and was blinded to its nature. In spinal group, patients received spinal anesthesia with hyperbaric bupivacaine (Astra Zenica, UK) 0.5% (7.5–10mg) which was administered via a 25-G spinal needle at L4-L5 or L3-L4 while the patient positioned in the sitting position under complete aseptic conditions.
In SOFT group, patients received SOFT block where patients were positioned in supine position under complete aseptic conditions, a linear US probe (GE LOGIQe, Wauwatosa, Wisconsin, USA) was placed on the inguinal crease to clearly show the femoral nerve and vessels as shown in fig.1. Using an in-plane technique, a 12-cm stimulating block needle was introduced medial to the femoral vein and advanced 1–3 cm below and parallel to the skin. Then, it was redirected toward the fibres of the femoral nerve, where 15 mL of bupivacaine 0.25% was injected. To block the obturator nerve, the probe was shifted medially, superior to the needle, and directed cranially to identify the pectineus muscle. The needle was then withdrawn to the subcutaneous tissue and redirected using an out-of-plane technique toward the deep surface of the pectineus, where 10 mL of bupivacaine (Astra Zenica, UK) 0.25% was injected (4). To locate the sciatic nerve, we used the curvilinear probe which was directed inferior to the needle, and tilted to get the clearest image of the sciatic nerve.
The needle was inserted then withdrawn subcutaneously and directed by an in-plane technique toward the sciatic nerve deep to the inferior border of the quadratus femoris muscle as shown in fig.2. Then 20 mL of bupivacaine 0.25% was injected after needle had elicited muscle twitches using 1 mA current. The techniques were evaluated every 5 minutes after completion and then
for 20 minutes. Baseline heart rate and blood pressure values were monitored every 5 min after block performance till the end of surgery. Hypotension was defined as a decrease in systolic arterial blood pressure by 20% or more from baseline values, and it was initially treated with 200 ml IV infusion of Ringer’s lactate solution; if this proved to be ineffective, an IV bolus of phenylephrine (40–50 mcg) was given. Bradycardia was defined as heart rate drops by more than 20% from the baseline values, and it was treated with 0.5 mg IV atropine.
The success rate of the surgical block was defined as a nerve block that allowed surgery without the need of rescue block, an infiltration of local anaesthetics in the surgical field, administration of rescue dose of analgesics or application of general anaesthesia to complete surgery.
At the end of the procedure, patients were transferred to the post-anaesthesia care unit (PACU) where they were followed up 24 hours after surgery by an experienced nurse and an end point assessor of the outcomes who were blinded to the nature of study and not part of it. Standard questions were asked about patient’s satisfaction and potential complications. Visual analogue score scale was used for assessment of postoperative pain. It is 10 cm scale where patients were taught to use this score to report the degree of postoperative pain from ’0’ to ’10’ with ’0’: no pain and ’10’: the worst imaginable pain. The same postoperative pain management protocol was followed for all patients. If pain score ≥ 4, patients were given fentanyl 50 μg i.v. bolus as a primary rescue analgesic which can be repeated after 1 hour until pain score < 4. In addition to intravenous infusion of acetaminophen 15 mg/kg 6 hourly was administeredas a secondary rescue analgesic.
Primary endpoint included duration of analgesia: the time to the first analgesic requirement. Secondary endpoints included patient satisfaction scores, visual analogue scores, the incidence of adverse events as back pain, post dural -puncture headache, vomiting, systemic toxicity of local anesthetics as seizures and cardiovascular collapse, persistent parathesia observed within 48 hours of the block.
In case of failure of the block or incidence of seizures resulting from local anesthetic toxicity, general anesthesia was given so those patients were excluded from the study.
In case of, cardiovascular collapse, the patients were treated with intravenous fluids and vasopressors.