Pericapsular nerve group (PENG) block is a new ultrasound (US)-guided nerve block, which has been used successfully to manage fractured hip pain. As an alternative approach to give PENG block, we have investigated the out-of-plane (OOP) approach instead of the in-plane approach, which is conventionally used. Ten patients aged between 55 and 72 years scheduled for hip surgery under spinal anesthesia were given US-guided PENG block by the OOP approach. The success of block was assessed by reduction in rest pain and pain during 15° straight leg raising (SLR) (passive SLR test) on a numeric rating Score (NRS) after 30 min of block. Ease of positioning score was also assessed during spinal anesthesia. The procedural difficulty was assessed by the number of attempts (needle re-insertion at the skin). All patients had successful blocks and showed a significant pain relief in resting pain (6.5 ± 1.3 vs. 3.8 ± 0.78) as well as pain during 15° SLR (8.5 ± 1.1 vs. 5.1 ± 0.73). All blocks required single needle entry; however, in three patients, medial redirection of the needle was required before final positioning. No complication was observed in any case. PENG block provides effective analgesia during positioning for spinal anesthesia in patients with hip fracture. OOP approach can easily be used as an alternative to conventional in-plane technique.
Keywords: Accessory obturator nerve, hip surgery, out-of-plane approach, peripheral nerve group block, regional nerve blocks, spinal positioning
| Introduction|| |
Hip fracture is the second most common fracture in the elderly population, and 90% of them require surgery. SIGN guidelines suggested that spinal or epidural anesthesia should be considered for all patients undergoing hip fracture repair unless contraindicated., However, positioning for spinal anesthesia is difficult in such patients because the hip fracture is painful, and approximately two-thirds of them have moderate-to-severe pain.
Opioids may cause delirium, and these patients often have existing comorbidities; therefore, regional blocks are superior to intravenous analgesia., Although the posterior part of the joint capsule is supplied by branches of the sciatic nerve, the majority of sensory innervation to the hip joint and capsule is from branches of the lumbar plexus (femoral nerve [FN] L2–4 and obturator nerve L2–4). The skin overlying the anterior and lateral part of the hip joint (through which incision is given) supplied by the iliohypogastric nerve (L1) and lateral femoral cutaneous nerve (LFCN) (L2, 3). FN block and fascia Iliaca block are commonly used techniques.,,
Femoral block leads to quadriceps weakness and fascia iliaca block, which is a facial plane block that requires a large volume of local anesthetic and inconsistent block of LFCN and obturator nerve. Lumbar plexus block is a very effective block. However, it requires a lateral decubitus position, which will be difficult in a patient with painful hip fractures. This block is deep and invasive block and has a risk of serious complications. A regional technique, which is safe and easy to learn and practice, could provide effective analgesia, but devoid of motor block was highly warranted.
Pericapsular nerve group block (PENG block) is a recently introduced ultrasound (US)-guided technique which provides effective analgesia for hip fracture patients. PENG block was based on blocking the articular branches of the FN and accessory obturator nerve (AON) in the region between the anterior inferior iliac spine and iliopubic eminence (IPE). As the articular branches are pure sensory nerves, this block provided excellent analgesia without affecting motor function.
The standard suggested technique for PENG block is an in-plane technique in which needle enters from the lateral side and targets inferomedially toward iliopectineal eminence. Since the introduction of PENG block and its usefulness to manage patients with hip fracture pain Other uses have been documented.,, To enhance the dexterity and ease of the procedure further, we investigated an out-of-plane (OOP) technique for the PENG block.
| Case Report|| |
After clearance from the hospital ethical committee to conduct the study, we randomly selected ten patients (six females and four males, 55–72 years of age), admitted with a hip fracture for surgery under spinal anesthesia. All patients were preoperatively optimized, and informed consent was obtained.
After aseptic preparation, PENG block was given with a 100 mm long, 22G blunt tip needle (Stimuplex, B. Braun) connected with a nerve stimulator (current 0.5 mA and frequency 2 Hz) to avoid inadvertent FN injury. Standard technique and low-frequency US probe (2–5 MHz, SonoSite, M-Turbo) were used to get a sonoanatomic view for the PENG block [Figure 1]. After local infiltration of the skin with 2 ml of 1% lidocaine, instead of using the in-plane technique, block needle was introduced perpendicular to the skin toward bony rim near iliopectineal eminence (IPE) using OOP approach [Figure 2]. Once bony contact was made; 20 ml of 0.25% bupivacaine mixed with 8 mg dexamethasone was injected after repeated aspiration to avoid accidental vascular injection. Correct needle placement was confirmed by a linear spread of local anesthetic below the fascial layer of the iliopsoas muscle [Figure 3].
|Figure 1: Sonoanatomic view for pericapsular nerve group block. ASIS: Anterior superior iliac spine, AIIS: Anterior inferior iliac spine, FA: Femoral artery, IPE: Iliopectineal eminence|
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|Figure 2: Out-of-plane needle entry and needle trajectory toward bony rim near IPE. AIIS: Anterior inferior iliac spine, FA: Femoral artery, IPE: Iliopectineal eminence|
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|Figure 3: Linear spread of local anesthetic below the iliopsoas muscle. FA: Femoral artery AIIS: Anterior inferior iliac spine, IPE: Iliopectineal eminence, IST: Iliopsoas tendon, LA: Local anesthetic|
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The procedural difficulty was assessed by the number of attempts (re-insertion of the needle after complete withdrawal from the skin). The readjustment of needle path after skin entry to the final target was recorded. The efficacy of block (analgesic effect) was assessed by measuring and comparing the resting pain and pain on 15° elevation of the affected limb before and after 30 min of the block by the numeric rating score (NRS) where 0 = no pain and 10 = excruciating pain. The comfort during positioning was also assessed in the operation room by the ease of positioning score (0 = cannot sit; 1 = sits with abnormal posturing; 2 = sits with wincing/without wincing with help or restriction; and 3 = sits on its own) [Table 1] and [Table 2].
All patients had a successful block and showed a significant pain relief in resting pain (preblock 6.5 ± 1.3 vs. 3.8 ± 0.78, P = 0.0001) as well as pain during 15° straight leg raising (SLR) (preblock 8.5 ± 1.1 vs. 5.1 ± 0.73, P = 0.0001). All blocks required single needle entry; however, in three patients, medial redirection of the needle was required before final positioning. No complication was observed.
| Discussion|| |
In the present study, the PENG block provided effective pain relief during positioning the patient for spinal anesthesia scheduled for hip surgery. Pain at rest, as well as during passive lift (15° SLR) of the limb on the fractured side, was significantly reduced. We used an innovative OOP approach for PENG block in our patient and found that this approach is easy to perform and safe. We used 20 ml of 0.25% bupivacaine with 8 mg dexamethasone. This concentration and volume provide safe and effective analgesia for positioning during spinal and have been used in previous studies. Mixing the dexamethasone increases the duration of analgesia without compromising safety.
PENG block is a versatile block. When the low volume of local anesthetic drugs (10 ml) is used, it only works on articular branches of femoral and AONs. When drug volume about 20 ml drug is used, it also covers the obturator nerve. However, studies have shown that when the volume of local anesthetic is increased up to 30 ml, other nerves such as femoral, obturator, lateral cutaneous, and genito FNs are also blocked.
Recently, the PENG block has been used for other indications such as stripping of veins in the lower limb, management of adductor spasm, and tumor excision.,, We postulated that the addition of a new approach might increase the dexterity of the procedure. Conventionally, the in-plane technique is used to give PENG block where the needle enters from the lateral side and directs inferomedially toward IPE. The in-plane technique has an advantage that the whole length of the needle can be seen. However, during the PENG block, it is not always possible due to the nature of the block (deep block) and anatomy of the lending surface, which is not linear.
Recently, concerns about injury to LFCN have been raised as this nerve lies in the trajectory of the needle during the in-plane approach and may get injured. On the other hand, the OOP technique has limitations about the visibility of the needle. Its advantage is that the needle has to travel a short distance, thus creates less discomfort to the patient.
In PENG block, the additional advantage is that there is no vital structure in the trajectory of the needle during the OOP approach, and contact with the bone is the endpoint. Therefore, the needle can be introduced easily and safely. The correct placement of the needle can further be confirmed by the spread of local anesthetic. The only theoretical concern could be an injury to the FN (present just lateral to the femoral artery). This can easily be avoided using nerve stimulators (as we have used) and redirected needle appropriately away from the FN.
Although we have used the OOP technique in a small number of cases (ten patients only), the block was successful in all the patients, and there was no procedural difficulty or complication. It is debatable that whether PENG block is a pure pericapsular block or not; but still, there is a scope for newer indications for PENG block.,, Therefore, it is prudent to explore other approaches that can affect its efficacy, safety, and usefulness.
This is only a small case series, and there are limitations inherent to this type of publication, such as lack of ability to generalize, publication bias, the danger of overinterpretation, and lack of anatomic studies to confirm the spread of local anesthetics and the nerves targeted.
| Conclusion|| |
PENG block provides effective pain relief in patients with hip fracture scheduled for hip surgery during positioning for spinal anesthesia. OOP approach can be used effectively and safely as an alternative approach while giving PENG block. A comparative study with more number of patients is required before generalizing the results and making any recommendation.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
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Conflicts of interest
There are no conflicts of interest.
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Duplex-63, Vijaya Heritage Phase-6, Kadma, Jamshedpur - 831 005, Jharkhand
Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]