|ORIGINAL CONTRIBUTION - CLINICS IN ORTHOPEDIC ANESTHESIA
|Year : 2018 | Volume
| Issue : 4 | Page : 221-226
Comparison of psoas compartment block and epidural block for postoperative analgesia in hip surgeries
Rajni Singh, Jeetendra K Bajaj, Davinderjit Singh
Department of Anaesthesia and Intensive Care, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi, India
|Date of Web Publication||29-Oct-2018|
Jeetendra K Bajaj
Department of Anaesthesia and Intensive Care, Vardhman Mahavir Medical College and Safdarjung Hospital, New Delhi
Source of Support: None, Conflict of Interest: None
Context: Psoas compartment block via lumbar paravertebral approach has been compared with epidural block for postoperative pain relief following hip surgery. Settings and Design: This prospective, randomized study was conducted in the department of Anesthesia in a tertiary care hospital. Materials and Methods: This study was conducted on 60 patients undergoing unilateral hip surgery. They were randomly assigned to either psoas compartment (P) or epidural (E) group (30 in each group). A lumbar paravertebral (psoas compartment) or epidural catheter was placed before the start of surgery. A subarachnoid block using 0.5% hyperbaric bupivacaine and fentanyl was subsequently administered. After 2 h, a loading dose of 10 ml of 0.25% bupivacaine was given, and infusion of the same drug started at 5 ml/h in group P and 5 ml/h of 0.125% bupivacaine in group E using an elastomeric infusion pump. The patients were observed for 24 h and quality of pain relief with both the techniques was compared. Statistical Analysis: Categorical variables were analyzed with Chi-square test while continuous variables were analyzed with Student's t-test. Visual analog scale was expressed as median and was analyzed with Mann–Whitney test. A software program (SPSS 21) was used. P <0.05 was considered significant. Results: The mean duration of postoperative analgesia in the epidural group was 551.11 min compared to 427.25 min in the psoas compartment group (P > 0.05), which was not statistically significant. Mean pain scores at 4 and 8 h postoperatively were higher in the psoas compartment block resulting in greater rescue analgesic requirement in this group. Conclusions: Psoas compartment block can be considered an alternative in patients with relative contraindications to epidural block such as those on deep vein thrombosis prophylaxis with anticoagulants.
Keywords: Epidural block, hip surgery, lumbar paravertebral, postoperative analgesia, psoas compartment block
|How to cite this article:|
Singh R, Bajaj JK, Singh D. Comparison of psoas compartment block and epidural block for postoperative analgesia in hip surgeries. Astrocyte 2018;4:221-6
|How to cite this URL:|
Singh R, Bajaj JK, Singh D. Comparison of psoas compartment block and epidural block for postoperative analgesia in hip surgeries. Astrocyte [serial online] 2018 [cited 2019 Mar 19];4:221-6. Available from: http://www.astrocyte.in/text.asp?2018/4/4/221/244301
| Introduction|| |
Hip surgery, especially in elderly with other comorbid conditions, is followed by particularly severe pain. This surgery entails massive nociceptive inputs from richly innervated joint tissue. Adequate postoperative pain relief improves the surgical outcome in terms of reduced morbidity, reduced hospital stay in the postoperative period, and reduced postoperative organ dysfunction due to lower surgical stress. One of the important goals of postoperative analgesia is to reduce opioid dose, and hence, side effects (nausea, itching, vomiting, respiratory depression, and ileus), leading to a delay in patient mobilization. When compared with pharmacological techniques, many regional analgesic techniques, such as epidural block, provide superior pain relief, may favorably influence outcomes with regard to blood loss and thromboembolic events, and can lead to substantial reduction of surgical stress responses. However, epidural block is associated with complications such as backache, headache, urinary retention, epidural hematoma, etc. The psoas compartment block, also called lumbar paravertebral block (PVB), blocks the nerves of the lumbar plexus, and is an alternative approach which may avoid many side-effects associated with epidural block, especially with regards to bleeding disorders and anticoagulation therapy.
This study was undertaken to compare the efficacy of psoas compartment block and lumbar epidural regarding the ease of administration, degree of pain relief, side-effects, and complications.
| Materials and Methods|| |
The study was a prospective, randomized, comparative study of 60 ASA grade I-II patients who were scheduled for unilateral hip surgery in the department of Anaesthesia in a tertiary care teaching hospital after obtaining approval from the ethics committee of the institution and informed consent from patients. All patients underwent a detailed pre-anesthetic examination, and were advised to fast overnight and to take tablet alprazolam 0.25 mg on the night before the surgery. On the morning of the surgery, patients were asked to take their routine medication for coexisting conditions. They were assigned to either psoas compartment (P) or epidural (E) group using a block randomization technique with a block size of 4.
Patient's heart rate, electrocardiogram (ECG), and noninvasive blood pressure were recorded, and intravenous line was started with an 18-Gauge cannula. Patients were preloaded with 10–15 ml/kg body weight Ringer's lactate solution before the procedure. They were supported in sitting position, while those who were unable to sit were positioned in a lateral decubitus position for administering the blocks. After ensuring all standard aseptic precautions, the epidural catheter and psoas compartment catheter were placed by the same operator in patients of groups E and P respectively. In Group E, after subcutaneous local anesthetic infiltration, an 18-G Tuohy needle was inserted in the L3-4 intervertebral space and the epidural space was located with a loss of resistance to air technique. A multiorifice catheter (Portex™) was inserted and advanced 3–5 cm into the epidural space. A test dose of 3 ml 2% lignocaine and 1:200000 epinephrine was injected through the catheter. This was followed by a spinal subarachnoid block, which was given using a 25-G spinal needle in L3-4 or L2-3 space, and 2.2 to 3 ml 0.5% bupivacaine and 10 μg of fentanyl was injected intrathecally. In group P, the puncture site for psoas compartment block was located in the following manner: a mark was made on the upper border of the spinous process of L4 vertebra on the operative side and 2 cm lateral to this point was the puncture site [Figure 1]. Local anesthetic was infiltrated subcutaneously at this site, and an 18-G Tuohy needle was inserted in the parasagittal plane parallel to the midline and the transverse process was located. The needle was then advanced off the superior border of transverse process to a depth of 1 cm, and conformation of psoas compartment was made using loss of resistance to air technique with a low friction syringe. The catheter was then introduced and advanced to a depth of 3–5 cm in the psoas compartment and secured by tunneling it subcutaneously [Figure 2]. The subarachnoid block was then administered in a similar manner as in group E. Regional anesthesia procedure time, i.e. time from positioning the patient to catheter fixation in both techniques, and the number of attempts required was noted.
In both groups, heart rate, noninvasive blood pressure, and SpO2 were recorded at regular intervals. The level of sensory blockade was assessed using loss of pinprick sensation. Patients were observed for discomfort, nausea, vomiting, shivering, pain, bradycardia, or any other side-effects. Intravenous fluids were administered in the form of Ringer's lactate, colloids, and blood as per estimated blood loss during the surgery. Two hours after administering subarachnoid block, the patients were given the study drug. Group P patients were given 10 ml of 0.5% bupivacaine in the psoas compartment using the previously placed catheter in paravertebral space and group E patients were given 10 ml of 0.25% bupivacaine through the epidural catheter. The bupivacaine infusion was started at the following rates: Group P, 5 ml.h−1 of 0.25% bupivacaine and Group E, 5 ml.h−1 of 0.125% bupivacaine using an elastomeric infusion pump (Fornia™). After concluding the surgery, patients were shifted to the wards for monitoring and observation. Postoperative pain was assessed using self-rating visual analog scale (VAS) ranging from 0 to 10 (0 = no pain and 10 = worst imaginable pain) at 2, 4, 8, 12, 18, and 24 h. On experiencing pain at VAS > 4, patients received injection diclofenac 75 mg intramuscularly (i.m) as the “ first rescue analgesic.” Time elapsed between the block given and the first rescue analgesia was noted and considered as the duration of analgesia. If pain was still not relieved, patients were given inj. tramadol 1.5 mg/kg i.m. Number of rescue analgesia injections received by the patient in 24 hours and the time of voiding urine were noted. The catheters in both the groups were removed after 24 h to enable the use of low molecular weight heparin for deep vein thrombosis(DVT) prophylaxis as per the hospital protocol.
To calculate the sample size and α error of 0.05 (type I error probability) and β error of 0.2 (power 80%) was accepted. Our hypothesis was to find at least a VAS difference between groups of 20 mm with a standard deviation (σ) of 25 mm during the postsurgery follow-up. Thus, a minimum sample size of 52 patients (26 patients for each group) was calculated and to reduce the margin of error thirty patients in each group were studied.
Categorical variables are presented in number and percentage (%) and continuous variables are presented as mean ± standard deviation (SD) and median. Normality of data was tested by Kolmogorov–Smirnov test. If the normality was rejected, nonparametric tests were used. Quantitative variables were compared using independent t-test/Mann–Whitney test (for nonparametric data) and qualitative variables were compared using Chi-square test/Fisher's exact test. A P value of < 0.05 was considered statistically significant. The data was entered in MS Excel spreadsheet and analyzed using Statistical Package for Social Sciences version 21 (IBM Corp, Armonk, NY, USA).
| Results|| |
The two groups of patients were comparable with respect to age, sex, weight, and types of surgery [Table 1]. The highest level of sensory block achieved, as assessed by a pinprick sensation, was similar in both the groups [Table 2].
The procedure time (the period from skin disinfection to completion of catheter insertion) between the two groups was statistically significant. The mean time required to perform epidural block was 10.47 min while it took 14.56 min to perform psoas compartment block (P < 0.05). Hemodynamic parameters, fluids administered, and duration of surgery were comparable between the groups.
Postoperatively, patients in group E were observed to have significantly lower visual analog pain score between time points T4 and T8 (P < 0.05) [Table 3].
Patients in the epidural group did not receive any rescue analgesia for a mean duration of 551.11 min while patients in the paravertebral group needed analgesia after a mean duration of 427.25 min (P > 0.05). Rescue analgesia was required in 9 of 30 patients in group E and in 20 of 30 patients in group P, which was statistically significant (P < 0.05) [Table 4].
The mean time of voiding urine in group E was 519.6 min while in group P it was 311.0 min. Two patients in group E required catheterization in the postoperative period due to retention of urine. The difference in time was statistically significant between the two groups (P < 0.05).
| Discussion|| |
Epidural analgesia after hip surgery is considered to be the gold standard for postoperative pain relief in these patients. The primary site of action of local anesthetic solutions injected into the epidural space is the spinal nerve roots. Sensory blockade interrupts the transmission of both somatic and visceral painful stimuli, whereas motor blockade provides muscle relaxation with a varying degree of sympathetic blockade.
Spinal and epidural anaesthesia have been shown to blunt the “stress response” to surgery, decrease intraoperative blood loss, lower the incidence of postoperative thromboembolic events, and decrease morbidity and mortality in high-risk surgical patients. However, these neuraxial techniques are not without an element of risk. The complications of epidural catheterization such as high or total spinal and infections are well known. Trauma to epidural veins occurs in approximately 10% of epidural placements and the incidence of hematomas after epidural blocks is estimated at 1:190,000. Neuraxial blockade at the lumbar level has been postulated to impair control of bladder function secondary to blockage of the S2 to S4 segments.
Psoas compartment block is actually a block of the lumbar plexus which comprises an injection of local anesthetic in the fascial plane within the posterior aspect of the psoas major muscle. Because the roots of the lumbar plexus are located in this plane, an injection of a sufficient volume of local anesthetic in the posteromedial compartment of the psoas muscle results in block of the majority of the plexus (femoral nerve, lateral femoral cutaneous nerve, and the obturator nerve). The anterior boundary of the fascial plane that contains the lumbar plexus is formed by the fascia between the anterior two-thirds of the compartment of the psoas muscle that originates from the anterolateral aspect of the vertebral body and the posterior one-third of the muscle that originates from the anterior aspect of the transverse processes. This arrangement explains why the transverse processes are closely related to the plexus and are therefore used as the main landmark during psoas compartment block.
At present, three different approaches to perform psoas compartment block have been described: (1) Loss of resistance technique, (2) nerve stimulator-guided technique, (3) ultrasound-guided technique. We have used the loss of resistance to a low friction syringe technique as this is a simple technique to learn and does not require sophisticated equipment.
In the nerve stimulator techniques, after the localization of the nerve by the desired evoked motor response, a bolus dose is given and then the catheter is placed without confirmation of the tip position. Thus, there is inability to assess the proximity of nerve to the catheter tip position. This problem has been overcome by using stimulating catheters. Various needles such as Contiplex Tuohy, Plexolong, Stimucath, and Polyplex T systems have been described but are not readily available in India.
In the ultrasound-guided technique, the psoas muscle is imaged through the acoustic window of the transverse processes. It appears as a combination of longitudinal hyperechoic striations within a typical hypoechoic appearance. Some of the hyperechoic striations may appear particularly intense and may be interpreted as the roots of the lumbar plexus. This unreliability is due to the intramuscular connective tissue which is indistinguishable from the nerve roots at such a deep location. Currently, there are very few practitioners of ultrasound-guided Lumbar plexus block. This may reflect the greater degree of skill required to perform the block.
Irrespective of the technique used, it is established that the use of paravertebral blocks are safer than epidural and that complications with this technique are infrequent. Most studies comparing the incidence of complications have been done for thoracic paravertebral and thoracic epidural blocks.
Hematoma following a paravertebral block has been reported to be approximately 2.4% and a risk of vascular puncture is approximately 6.8%. Usually, hematoma is limited in magnitude and certainly not associated with any major symptoms. Hypotension has been reported in 4% of thoracic paravertebral blocks compared to 30% in thoracic epidurals. Hypotension could be attributed to the sympathetic blockade, epidural spread, or effect of local anesthetics on the vascular tone.
Epidural or intrathecal spread has been estimated to occur between 1% and 70% in paravertebral blocks.,
In the present study, we compared postoperative analgesia provided by 10 ml/h each of 0.25% bupivacaine epidurally and 0.5% bupivacaine given in the psoas compartment. The difference in the concentration of bupivacaine is based on the results of previous studies by various authors. The dose of bupivacaine in epidural group is lower as use of higher rate and concentration leads to hypotension. There is qualitatively a greater block of somatic nerves together with block of sympathetic chain and the rami communicans when the local anaesthetic is placed alongside the vertebral column rather than anatomically distant from it in the paravertebral space. We considered and dismissed the idea of using equal doses of bupivacaine as we aimed to optimize the use of each of these two local anesthetic techniques. We were unable to use any more bupivacaine through the epidural route because of hypotension, nausea, and vomiting associated with larger doses, and decreasing the dose of bupivacaine used in the psoas compartment would have disadvantaged this group of patients.
In our study, the mean duration of analgesia (determined by the time interval to first rescue analgesic requirement) was 551.11 min in the epidural group while patients in the psoas compartment block group needed analgesia after 427.25 min (P > 0.05). However, there was a statistically significant difference between the two groups regarding the mean pain scores at 4 and 8 h postoperatively resulting in a greater number of rescue analgesics in the psoas compartment block group compared with that in the epidural group. Our findings corroborate the findings of previous studies of Bosch et al., in which the average scores on the visual analogue pain scores (VAPS) for both the procedures were comparable; however, local anesthetic and opiate consumption was significantly higher in the psoas compartment block group compared with the epidural group. Turker et al. found no statistically significant difference in VAS pain scores and consumption of rescue analgesia after surgery in both groups. Surange et al. reported no statistically significant differences between the groups with regard to mean pain scores in the first 48 h.
In our study, the difference in the quality of analgesia in the two groups can be explained by several factors. First, patients requiring hip replacement surgery frequently have bilateral hip joint pathology. An epidural provides effective analgesia to both hip joints. It has been reported that patients with a psoas compartment block often experience pain in the contralateral joint due to positioning postoperatively (abduction of hips to prevent dislocation of the prosthesis). Second, patient-controlled epidural analgesia is associated with less local anesthetic consumption, more effective pain relief and improved patient acceptance. One reason for this is that boluses injected epidurally spread more extensively than a continuous infusion. Similarly, patient-controlled peripheral (nerve or plexus) analgesia leads to better pain relief and lower opiate consumption. Third, a large volume of local anesthetic is required to block the entire lumbar plexus with a psoas compartment block, which often requires dilution of the local anesthetic to stay below the toxic dose. Consequently, the quality of the block may decrease. In an epidural block, volumes and bupivacaine concentrations are usually within safe limits. Fourth, it has been demonstrated that there are anatomical variations in the formation of the lumbar plexus in more than 40% of cadavers. In 12%, an accessory obturator nerve arising from the anterior divisions of the L3 and L4 nerve roots which does not lie in close approximation to the obturator nerve was present. This anatomical variation can explain inadequate block during hip surgery. Finally, the lumbar plexus lies within the psoas muscle substance, and thus, the psoas compartment provides only an indirect access to the lumbar plexus. Capdevila et al. demonstrated radiologically that the catheter tip lies within the psoas major muscle in 74% of the patients and between the psoas and quadratus lumborum muscles (psoas compartment) in 22% of the patients. With ultrasonic guidance also, the lumbar plexus is a deep structure that is difficult to visualize. Further development of ultrasound-guided placement of psoas compartment blocks may well improve the success rate and quality of the block, decrease the amount of local anesthetic required and minimize complications.
Several other authors have also studied the efficacy of psoas compartment block for providing pain relief after hip surgery. Touray et al. conducted a systematic review of the efficacy and safety of psoas compartment block for anesthesia and postoperative analgesia for hip and knee surgery. Amiri et al. showed that, by preserving hemodynamic stability, lumbar plexus block in conjunction with a light sedation could be considered as a reliable, prudent, and satisfying anesthetic option in the management of hip fractures in the elderly patients with three beneficial characteristics of safety, effectiveness, and acceptability.
In the present study, we noted one advantage in the psoas compartment block group that the mean time of voiding urine in the postoperative period was much longer in the epidural group compared to the psoas compartment block group. This difference was both statistically and clinically significant. Two patients in the epidural group required urinary catheterization in the postoperative period due to retention of urine. This is explained by neuraxial blockade at the lumbar level that impairs bladder control secondary to the blockage of S2–S4 segments. No patient in the psoas compartment block group needed urinary catheterization.
| Conclusions|| |
The mean duration for postoperative analgesia in the epidural group was comparable to the paravertebral group. The average scores on the visual analogue pain scale for both the techniques were comparable except at 4 and 8 h postoperatively, resulting in greater number of rescue analgesics in the psoas compartment group than the epidural group. Thus, from this study we conclude that, while either of the two techniques can be used in patients undergoing hip surgery, psoas compartment block should be considered as an alternative to epidural block in patients with relative contraindications to neuraxial block, such as those on anticoagulant therapy for DVT prophylaxis.
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Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]
[Table 1], [Table 2], [Table 3], [Table 4]