Background: this study aimed to describe the pain relief outcomes after hip replacement surgery by continuous Pericapsular Nerve Group Block (PENG Block) in combination with lateral femoral cutaneous nerve (LFCN) block under the guidance of ultrasound.

Methods: patients who had hip surgery at E University hospital, Hanoi, Vietnam from August 2021 to August 2022 belonged to two groups: group of patients with pain relief with PENG block in combination with LFCN block (PENG BLOCK group) and group of patients with patient-controlled intravenous analgesia (PCA group). Outcomes regarding clinical and pain score from initiation of insertion or PCA insertion (H0) to after 72 hours (H72) were recorded.

First, patients were explained about the study and asked to sign written informed consent if they agreed to participate in the study. Next, the patient was instructed to use the visual analogue scale (VAS) for pain score, as well as how to press the button to request pain relief. Then, a monitor was installed and operated to assess the clinical parameters (electrocardiogram, blood pressure, SpO2, arterial blood pressure, temperature). The patient was oxygenated 3-5 liters/minute and performed a peripheral intravenous line, with an 18G catheter, infused with 0.9% NaCl solution. Spinal anesthesia was administered with ropivacaine 0.5% and fentanyl.

During and after the surgery, a group of patients received intravenous morphine analgesia via PCA (concentration 1mg/ml, bolus dose of 1mg, lock time 10 minutes, maximum dose 10mg/4 hours). The remaining group of patients receive pain relief by PENG block and LFCN block. In this group, the ultrasound probe was placed horizontally from the anterior superior iliac spine, and was moved along the femoral arc defining the pubic spine. Then, the transducer was rotated 45 degrees, moved parallel to the femoral arch identifying the anterior inferior iliac spine (AIIS), iliopubic eminence (IPE) and inferior lumbosacral head. The ultrasound probe was moved lightly until the upper end of the femoral head was identified. Next, a 120 mm Tuohy 18G anesthetic needle was used under ultrasound guidance, which was moved lateral to medial in the plane between the ultrasound transducer and the superior tip of the femoral head. Then, 10 mL of ropivacaine 0.25% was injected through the anesthetic needle tip.

Data were collected at different times including: before surgery, before anesthesia, during surgery and after surgery. The information was recorded in the medical record.

Preoperative data: the collected information included the general characteristics of the study patients including age, gender, weight, height, history of smoking/motion sickness, diagnosis, health classification according to ASA, liver and kidney function tests. With pre-anesthesia data, information was collected including pulse, blood pressure, respiratory rate, SpO2.

Intraoperative data: the information collected includes information about anesthesia and surgical procedure.

Post-operative data: the collected information includes blood test results (urea, creatinine, liver enzymes), pain score (Visual analogue scale - VAS - scale from 0 to 10, the higher the score, the higher the pain level. more), analgesic drugs consumption status, respiratory and circulatory changes, adverse events, and analgesic satisfaction. Time was recorded from initiation of catheterization or PCA insertion (H0) to after 72 hours (H72).

Inclusion Criteria:

• American Society of Anesthesiologists (ASA) physical status I-III.
• Patients had hip replacement surgery.

Exclusion Criteria:

• infection of the anesthetized area.
• coagulation disorders
• organs dysfunction
• allergy to anesthetics
• did not cooperate with physicians
• history of opioid dependence
• inability to participate in the study

We agree that all results and conclusion of this research will be used fully for other researchers

from September 2023 to the unidentified time

anesthesiologists, surgeons all over the world