Comparative Study to Evaluate the Effect of Ultrasound-Guided Pericapsular Nerve Group Block Versus Fascia Iliaca Compartment Block on the Postoperative Analgesic Effect in Patients Undergoing Surgeries for Hip Fracture under Spinal Anesthesia.

Background: Fractures in and around the hip are a major concern in young as well as the elderly. Ultrasound-guided (USG) peripheral nerve blocks help in early surgical fixation of these fractures by providing perioperative pain relief as well as early mobilization resulting in reduced morbidity and mortality. Aims: This study aims to compare the efficacy of USG pericapsular nerve group (PENG) block versus fascia iliaca compartment (FIC) block. Setting and Design: Prospective, randomized, double-blind, controlled study. Materials and
Methods: Twenty-four patients above 18 years of age with hip fracture belonging to the American Society of Anaesthesiologists physical status Classes I and II scheduled for hip surgery were randomly allocated into two groups. Group 1(PENG block) received USG-guided PENG block and Group 2 (FIC block) received USG guided FIC block for postoperative pain relief. Postoperative pain relief (at rest) was evaluated by Numeric Rating Scale score from 20th min and at regular interval for 24 h. The total analgesic consumption in the first 24 h was also noted. Statistical Analysis Used: Data were analyzed by using nonparametric test and Chi-square test. Hemodynamic variables and pain scores were analyzed using analysis of variance for two groups and independent t-test was used for comparison between two groups.
Results: Postoperative NRS score was higher in FIC block than PENG block which was statistically significant at 1 h (P = 0.035) and at 4 h (P = 0.001). The first requirement of analgesic was significantly late in PENG block group (8.17 ± 3.129) as compared to FIC block group (4.00 ± 1.477). Conclusions: PENG block provides better postoperative analgesia, with reduced requirement of rescue analgesics in 24 h as compared to FIC block in patients undergoing surgeries for hip fracture under spinal anesthesia. Copyright:

INTRODUCTION

Fractures in and around the hip are quite common irrespective of both the young and elderly population groups and are associated with extreme pain. A hip fracture is a serious injury, with complications that can be life-threatening and is a common orthopedic emergency in the elderly.[1] Early surgery within 48 h of fracture has shown to decrease the complication and mortality rates.[2].

Fascia iliaccompartment (FIC) block has been routinely used for postoperative analgesia following surgeries for hip fractures and is widely believed to offer fast and adequate pain relief with fewer adverse effects in the elderly.[34] The efficacy of the fascia iliac block to manage pain from the fracture site has been well documented in literature.[5] The effect of analgesia from these blocks is only moderate and the previous research studies suggest that the obturator nerve (ON) is not covered. The ON, accessory ON (AON), and femoral nerve, supplies the anterior hip capsule according to the previous anatomic studies.[67] The anterior capsule is utmost innervated portion of the joint, indicating that these nerves should be the vital targets for hip analgesia. Short et al.[8] documented that the anterior hip capsule is supplied by 3 main nerves of which AON, and femoral nerve is found to play a major role in anterior hip innervation compared to previously reported data. The high articular branches from FN and AON are consistently found between the anterior inferior iliac spine (AIIS) and the Iliopubic Eminence(IPE), whereas the ON is found close to the inferomedial acetabulum. This anatomical knowledge has led to a new interfacial plane block to target the articular branches of hip, hence the Pericapsular nerve group (PENG) block was introduced, which provides good analgesia to hip.

AIMS

With this background, the present study was designed to evaluate the efficacy of postoperative analgesia in terms of NRS (numeric rating score) as primary objective in ultrasound guided techniques namely FIC block and PENG block in patients undergoing surgeries for hip fracture. Secondary objectives: (1) Time to first rescue analgesic (duration of analgesia) (2). Rescue analgesia consumption (intravenous [i.v.] Paracetamol 1 g) in 24 h.

MATERIALS AND METHODS

The institute ethical committee approval (IEC/PP/2017/27) was obtained, and the study was done over a period of 2 years from 2017 to 2019 in a teaching hospital in south India. The ethical principles for medical research involving human subjects in accordance with the Helsinki Declaration 2013 was followed, an informed consent was obtained in English and regional language from all patients. This study was conducted on 24 patients, the American Society of Anesthesiologists (ASA) PS classes I and II, patients of either sex, above the age of 18 who were undergoing Dynamic hip screw fixation or hemiarthroplasty. Exclusion criteria included patient refusal for regional anesthesia, history of local anesthetic (LA) allergy, bleeding disorder, anticoagulant therapy, local-site infection, and ASA PS Clases III and IV.

We included 12 patients for each group and were randomly allocated using computer-generated random number into two groups. Group 1(PENG block) patients received PENG block under ultrasound-guided (USG) guidance using curvilinear low-frequency ultrasound probe (2–5 MHz) (SonoSite™ M-Turbo, Bothell, WA, USA) initially placed in a transverse plane over the AIIS and then aligned with the pubic ramus by rotating the probe counterclockwise approximately 45 degrees to visualize the Iliopubic Eminence (IPE), the iliopsoas muscle and tendon, the femoral artery, and pectineus muscle. A 23Gauge Quincke needle was inserted in-plane and the needle tip is positioned in the musculofascial plane between the psoas tendon anteriorly and the pubic ramus posteriorly. 20 mL of 0.5% ropivacaine was injected in increments while observing for an adequate fluid spread in this plane.

Group 2 (FIC) patients received FIC block under USG guidance using high-frequency linear transducer (6–13 MHz) was used to identify the femoral artery at the level of the inguinal crease. Immediately lateral and deep to the femoral artery and vein the iliopsoas muscle is overlaid by a hyperechoic fascia iliaca. The femoral nerve is seen lateral to the femoral artery wedged between the iliopsoas muscle and the fascia iliaca. Maneuvering the transducer laterally helps to visualize the sartorius muscle covered by its own fascia alongside the fascia iliaca. A line is drawn connecting the anterior superior iliac spine to the pubic tubercle, the needle tip is positioned at lateral third of the line under the fascia iliaca. 20 mL of 0.5% ropivacaine is injected until it spreads laterally toward the iliac spine and medially toward the femoral nerve.

The USG PENG and FIC block was performed by an anesthetist who is trained in regional anesthesia and did not take part in monitoring the patient. Thus, the anesthesiologist performing the block and taking care of the anesthetic was blinded to the type of block given to patient, another anesthetist monitored the intraoperative period and the postoperative period. The NRS scoring was recorded by trained postoperative staff nurse.

All necessary precautions for safe administration of the local anesthetics viz recurrent aspiration, good needle visualization during injection was taken. The assessment of the PENG and FIC block was done using cotton wool bud soaked in surgical spirit by a blinded observer who was not present at the time of the performance of block.

All patients received spinal anesthesia following the block. Standard monitoring of 3 lead electrocardiography, noninvasive blood pressure, pulse oximetry (SpO2), were monitored.

Preoperative Baseline Numeric Rating Scale (NRS) score was assessed, and block was performed. NRS score was reassessed at 15 min and 30 min after completion of block by passive internal rotation and the patient was positioned for spinal anesthesia. After the surgical, procedure was over patient was shifted to post anesthesia care unit (PACU).

In the PACU, the NRS score was recorded at 20th min 1st, 4th, 6th, 12th, 18th, and 24 h. If the patient experienced pain (NRS score >6) at any hour, intravenous paracetamol (1 g) was administered as rescue analgesic. The use of rescue analgesics, as well as NRS scores at designated hours, was recorded. Adverse effect after giving block and spinal anesthesia were monitored (nausea, vomiting, hypotension, and bradycardia) if present were also recorded. Bradycardia was treated with atropine (0.6 mg i.v.) which is defined as heart rate <50 beats/min. A decrease of mean arterial pressure (MAP) of more than 30% from baseline was considered as hypotension and treated with rescue i.v. Mephentermine (6 mg) and i.v. fluids (5 mL.kg −1) until MAP 70 mm of Hg. Incidence of postoperative nausea and vomiting (PONV) was documented and managed with injection Ondansetron 4 mg.

The sample size calculated based on the parent article in which FIC block was used for hip arthroplasty,[9] the mean analgesic consumption was 246.3 and standard deviation (SD) was 85.5 and in the control group mean was 351 and SD was 87.5 at 24 h, using 95% alpha error and 80% power, the sample size was calculated by Open Epi software (Open-source.org, version 3.03a, Emory University, Atlanta, Georgia, USA) to be total of 22 (11 in each group). We planned to include 24 patients (12 in each group).

Statistical analysis was done using the Epi Info 7.0 software (developed by CDC, Atlanta, Georgia, USA) for Windows. Data were analyzed by using nonparametric test and Chi-square test. Hemodynamic variables and pain scores were analyzed using analysis of variance for two groups and independent t-test was used for comparison between two groups. P < 0.05 was considered statistically significant.

RESULTS

Twenty-four patients enrolled in the study who received either PENG block or FIC block were analyzed, there was no dropout or failed block [Figure 1]. Both the groups were comparable in with respect to operative procedures and duration of surgery. There was a drastic reduction in the NRS scores from baseline to 30 min and later NRS scores varied gradually at regular time intervals in both the groups. Independent sample t-test showed statistically significant difference between the groups at postoperative PENG block 1 h (P = 0.035) and at 4 h (P = 0.001) [Figure 2]. The time required for first rescue analgesia was significantly (P = 0.00) late in PENG block group (8.17 ± 3.129) as compared to FIC block group (4.00 ± 1.477) [Table 1]. Number of patients requiring 3 doses of rescue analgesia in 24 h were 3 (12) in FIC block and only 1 (12) in PENG block. Similarly, 4 (12) in PENG block group compared to 8 (12) in FIC block required two doses of rescue analgesia over 24 h. A single dose of analgesic over 24 h was adequate for7 (12) patients in PENG block compared to only one patient in FIC block group. The total dose of rescue analgesia in both groups were not statistically significant in both the groups. PONV was present more in PENG block group (25%) compared to FIC block group (8.3%) [Table 2]. However, there have been no statistically significant differences.

Figure 1

Consort diagram

Figure 2

Comparison of the NRS scores between the groups (PENG block and FIC block) at different time intervals. NRS scores = Numeric Rating Scale, PENG = Pericapsular nerve group, FICB = Fascia Iliaca compartment

Table 1

Comparison of the time (hours) of first rescue analgesia between the groups (pericapsular nerve group block and fascia iliaca compartment block)

Variable	Groups (mean±SD)		P*
	PENG block	FICB
Time (h) of first rescue analgesia	8.2±3.1	4.0±1.5	0.00

PENG=Pericapsular nerve group, FICB=Fascia iliaca compartment block, SD=Standard deviation

Table 2

Comparsion of the postoperative nausea and vomiting between the groups (pericapsular nerve group block and fascia iliaca compartment block)

	Variable	PENG block	FICB	P
PONV	Nil	9 (75.0)	11 (91.7)	0.27
	Yes	3 (25.0)	1 (8.3)

PENG=Pericapsular nerve group, FICB=Fascia iliaca compartment, PONV=Postoperative nausea and vomiting

DISCUSSION

In our study, there was no significant difference observed in the mean duration of surgery between PENG block and FIC block groups. Continuous FIC block and continuous FNB were compared by Yu et al., as a part of for postoperative analgesia in elderly patients who underwent hip replacement under general anesthesia.[10] There was a drastic reduction in the NRS scores from baseline to 30 min and later NRS scores varied gradually at postoperative time intervals in both the groups in our study. On comparison of the NRS score in both PENG block and FIC block groups, at postoperative block 1 h (P = 0.035) and at 4 h (P = 0.001) statistically significant difference was observed in our study. Furthermore, in our study, the first rescue of analgesic was significantly late in PENG block group than FIC block group and reported a significant difference between the two groups [Table 1]. Several research studies reported in the literature demonstrated the decreased analgesic requirement in group where either FNB or FIC block was used.[111213] In the present study, there was no significant difference between the groups was observed with regards to total doses of rescue analgesic required.

With a comprehensive scientific basis of the limited existing literature, the PENG block is a new regional block, offering a superior analgesia, with opioid-sparing effect, particularly in the population at risk of complications from opioid analgesia.[141516] Furthermore, we know that pain (a result of ineffective analgesia) itself is a risk factor for agitation and delirium.[171819] It follows that there would be an improvement in patient safety and patient outcomes from wider adoption of a such superior regional analgesic techniques.

The nerve supply of the hip joint has been studied extensively. An anatomic study by Short et al. confirmed that high branches of both the femoral and ONs supply the anterior hip capsule.[8] It is understood that the anterior hip capsule receives the major sensory innervation, whereas the posterior capsules receive innervation from nerve to quadratus femoris. The medial capsule of the hip receives nerve supply from AON.[82021] Peripheral nerve blocks not only provide excellent analgesia; they also reduce postoperative inflammatory response.[2223] The FIC block is a relatively new component of the hip fracture analgesia armament gaining rapid popularity.[2425] However, there is disagreement about the exact neuroanatomy targeted by FIC block.[26] Magnetic resonance imaging has helped to confirm that LA spread following FIC block does not regularly cover the ON.

As of now we have only a limited case series published on this new technique PENG block, which has demonstrated excellent analgesic for patients with hip fracture. The median reduction of pain scores showed a larger decrease when compared with other regional techniques for hip fractures.[27] The advantage of the PENG block is having a pain-free patient during positioning for procedure, with relatively no motor weakness and prolonged analgesic efficacy.[9] The limitation of this new PENG block is that it ought to be combined with other nerve blocks like FIC block for more comprehensive analgesia for hip surgery. is that it. The lateral femoral cutaneous nerve block can be combined with PENG block to provide good analgesia for hip surgeries.[28]

FIC block has been extensively studied for its efficacy in reducing pain of fracture neck of femur and postoperative pain. A recent Cochrane review that evaluated eight randomized control trials (RCT) with high level of evidence and included 4 RCTs comparing FIC block to systemic analgesics showed reduction in NRS pain score of roughly 3.4 of 10 on movement within 30 min after block placement.[29] Eleven trials and 937 patients were included in a meta-analysis and NRS score was assessed at regular interval for FIC block and placebo group. Compared to the control group, FIC block group had reduced NRS score at 1–8 h and 12th hours.[30]

Various meta-analyses have shown the role of different nerve blocks for postoperative analgesia in lower limb surgeries. Dye was injected in a cadaveric study to demonstrate PENG block, the entire anterior hip capsule area in relation to articular branches of femoral nerve, ON, and AON were stained.[8] Hence, PENG block, provides profound hip analgesia amidst all the regional analgesia techniques until now described. Because PENG block covers the main articular branches supplying the hip joint, it gives good pain relief at rest and movement, like sitting upright.

The PENG block is now more widely used and studied for hip fracture pain with affirmative evidence from few case reports. A combination of regional anesthesia with neuraxial block for hip surgery has an advantage that patient can be comfortably position for spinal anesthesia, this new technique will be boon for perioperative pain management of patients with hip fracture right from emergency room. Although studies have shown FIC block delivers analgesia in hip fracture, however, the recent anatomic studies of hip innervation as discussed earlier suggest, PENG block is suited for more perfect and superior hip analgesia.

While assessing the recue analgesia, patient-controlled analgesia with opioids would have been a better option compared to on-demand NSAID, which is one of the limitations of the study. Second, comfort and satisfaction of the anesthetist performing the spinal anesthesia after PENG block and FIC block should have been considered. Future study must be planned with adequate sample size and assessment of motor sparing of PENG block.

CONCLUSIONS

To the best of our literature knowledge, the findings of the present comparative study demonstrated that PENG block can produce a better postoperative analgesic effect with reduced consumption of rescue analgesics in comparison to FIC block in patients undergoing surgeries for hip fracture. However, large comparative studies with a greater number of samples are warranted to further validate the efficacy and superiority of PENG block over FIC block.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.