Comparison of spinal anaesthesia and erector spinae plane block in unilateral inguinal hernia: Randomised clinical trial

Abstract

Introduction:

The objective of our study was to compare erector spinae plane block (ESP) with spinal anaesthesia (SA) for inguinal hernia repair with respect to anaesthetic efficacy, post-operative analgesia, mobilisation, discharge, complication and side effects.

Patients and Methods:

The study included 52 patients over 50 years of age, with the American Society of Anaesthesia physical status Class I-III. Group ESP (n = 26) was applied 30 ml of mixed local anaesthetic mixture applied at the L1 level to the plane of the erector spinae and 10 ml of tumescent when necessary, while Group SA (n = 26) was applied 3 ml of 0.5% bupivacaine at the L3–L4/L2–L3 level.

Results:

Intraoperative Visual Analogue Scale (VAS) value was lower in Group S, whereas the 6^th-h VAS value was lower in Group ESP (P < 0.05). There was no significant difference between the VAS values at hour 12 and 24 (P > 0.05). Reaching post-anaesthesia discharge criteria 9 and time to mobilisation and oral feeding was shorter in Group ESP, whereas post-procedure waiting time was shorter in Group S (P < 0.05). While the need for post-operative analgesics was higher in Group S (P < 0.05), there was a high level of patient satisfaction in Group ESP (P = 0.05). Intraoperative midazolam requirement was lower in Group S, post-operative diclofenac requirement was lower in Group ESP (P < 0.05), post-operative urinary retention and tremor were higher in Group S (P = 0.05).

Conclusion:

ESP block provides adequate surgical anaesthesia compared to SA (non-inferiority) for inguinal hernia repair. It is associated with less analgesic requirement, low post-operative pain, less complication rate and high patient satisfaction in the post-operative period.

INTRODUCTION

Erector spinae plane block (ESP) was first described in 2016 as a regional block technique for thoracic neuropathic pain. Since then, the interfascial plane block has been successfully used as an alternative to neuraxial block in various surgeries.[1]

Since ESP is associated with fewer complications such as direct spinal cord injury, epidural haematoma and central nervous system infection, which are seen in neuraxial blocks, it has recently been used as an alternative analgesic and a safer anaesthesia technique.[2]

ESP block has emerged as an effective regional anaesthesia technique for thoracic, abdominal and other regions. ESP is easy to administer and has a low risk of serious complications. Therefore, it is gaining popularity.[3] Today, ESP is used to provide analgesia in procedures such as pyeloplasty, lipoma excision, breast reconstruction, malignant mesothelioma and hip reconstruction, and there are reports of its use in paediatric inguinal hernia repair.[4]

Although there are many case reports on ESP, controlled clinical studies on this subject are not yet sufficient. ESPs are mostly administered to adult patients from the thoracic region with a single injection technique. Although generally used for thoracic analgesia, they are secondarily used for analgesia and anaesthesia applications in lumbar surgeries.[5]

One-third of the patients admitted to the hospital due to gastrointestinal diseases suffer from an abdominal hernia. Ninety-six percentage of these patients apply for inguinal hernia.[6] Repair of inguinal hernia can be performed under general anaesthesia, regional or local anaesthetics. Despite various side effects such as post-spinal headache, urinary retention, motor deficit of lower extremities, intraoperative haemodynamic variations, delayed mobility and hospital discharge, spinal anaesthesia (SA) remains the most commonly used anaesthesia method in inguinal hernia repair.[7,8]

Based on the current scientific data supporting the use of local infiltration and peripheral nerve block anaesthesia, one may wonder why this technique is used for only 10% of all operations and not translated into general practice.[9] The infrequent use of local anaesthetic and peripheral nerve block methods can partly be explained by traditions in the practice of anaesthesia. In addition, many surgeons are probably reluctant to learn the technique of regional infiltration anaesthesia as well as to learn and practice peripheral nerve blocks for anaesthesia. They may find it easier to operate with spinal or general anaesthesia, although it poses a higher risk in terms of patient comfort and complications.[7]

Controlled clinical studies with well-explained and applicable methods are needed to popularise the use of peripheral nerve blocks or infiltration anaesthesia against SA. In this way, ESP may be a suitable alternative, especially for middle-aged patients with comorbidities and for whom SA is thought to increase the relative intraoperative risk.

The primary aim of our study was to compare the lumbar erector spinae blocks supported with local infiltration anaesthesia versus SA applied in unilateral inguinal hernia surgery in middle-aged and older patients in terms of the operation time, intraoperative haemodynamic data, onset time, analgesic requirement and discharge time, while the secondary aim was to assess patient satisfaction, surgeon satisfaction and procedure-related complications such as nausea, vomiting, urinary retention, headache, tremor and bleeding.

PATIENTS AND METHODS

After the study was approved with the decision of the ethics committee of Nigde Omer Halisdemir University, dated 28^th August 2020 and numbered 2020/38, and registered in the ClinicalTrials.gov (NCT05073055) before patient recruitment. The suitability of 70 cases who were admitted to the general surgery clinic for surgery with the diagnosis of unilateral inguinal hernia and were classified under the American Society of Anaesthesia physical status (ASA) I-III class, aged between 50 and 75 years old, was evaluated. The study was designed as a prospective, randomised controlled study. Eighteen patients were excluded from the study due to various reasons at different stages, and a total of 52 patients were included in the statistical evaluation [Figure 1].

Figure 1.

Consolidated standards of reporting trials statement flow diagram. SA: Spinal anaesthesia, ESP: Erector spinae plane block

The study was conducted in accordance with the principles of the Declaration of Helsinki. The patients were selected 1 day in advance by the single-blind and the closed-envelope method, and informed consent was obtained from all patients after the study design was explained in detail.

Patients who were 20% above their ideal body weight, had liver disease, were allergic to anaesthetic agents, had local infection, relapse, strangulated hernia, history of allergy to local anaesthetics and a history of anaesthesia up to 2 weeks priorly were excluded from the study. The general surgeon who performed the inguinal hernia repair surgery did not take part in patients’ post-operative follow-ups.

All patients were administered 0.05 mg/kg of midazolam for pre-operative sedation 10 min before the block application. Before anaesthesia, electrocardiogram (ECG), heart rate (HR), peripheral oxygen saturation (SpO₂) values were monitored in the preparation room and nasal administration of 2 lt/min of O₂ was started.

Patients were randomised into two groups. Patients who underwent SA were named Group S, and patients who underwent erector spinae block and tumescent anaesthesia were named Group ESP. Group (S) (n = 30): Patients to undergo SA were placed in a sitting position on the operating table and entered through the subarachnoid space at the level of L3–L4/L2–L3 under sterile conditions with a 25G cutting quincke spinal needle (Egemen, Turkey) and were injected 3 ml of 0.5% hyperbaric racemic bupivacaine (15 mg) in 30 s. The patients were placed in the supine position right after the spinal block and the intervention was started after the pinprick test confirmed that the level of the sensory block was in the T10 dermatome. Surgery was allowed in patients who developed sensory block at the T10 level. Patients who did not develop enough sensory block for the intervention despite a waiting period of 10 min were recorded and excluded from the study, and an additional anaesthesia method was applied. Three patients in the SA group and two patients in the ESP group were excluded due to unsuccessful block.

A total of 40 ml mixture was prepared by mixing 15 ml of 2% lidocaine hydrochloride (10 mg/ml) with 15 ml of % 0.5 bupivacaine hydrochloride (5 mg/ml), 5 ml of serum 8.4% sodium bicarbonate and adrenaline tartrate (5 μg/mL) complemented to 5 ml with physiological saline. The mixture was administered to each patient in Group (ESP) (n = 30) before the operation to create a tumescent anaesthesia-assisted erector spinae block in patients undergoing erector spinae block with infiltration anaesthesia.

After haemodynamic stability, the patients were placed in a sitting position and infiltration anaesthesia was administered with 2% lidocaine. Following aseptic preparation of the skin and probe, a medium-frequency curvey ultrasound (USG) transducer was first placed in the midline to visualise the transverse projection of the first lumbar (L1) vertebra. L1 vertebra was determined as the first vertebra of the transverse process (TP) that does not continue with the rib and then it was moved 2.5 cm laterally in the parasagittal plane, after imaging the TP, in-plane spreading was injected. Hydrodissection was achieved on the TP of L1 by using a 5 cm, 21G peripheral nerve block needle (Pajuk®, stimupleks HNS12 Germany) just below the erector spinal muscle with real-time imaging of the substance. Afterwards, a unilateral injection was completed from the same side of the inguinal hernia at L1 level, with an additional 25 ml from the same insertion point Figure 2.

Figure 2.

Ultrasonographic image of the ESP. (a) Anatomical localization of the erector spina plane at L1 level, (b) distribution of local anaesthetic after injection. ESP: Erector spina plane block

After the needle was removed, the injection site was applied pressure for 1 min, and then, the level of sensory block in the inguinal region was checked periodically. The patient was taken to the operating room after sufficient sensory block was formed and the operation was started. A maximum of 5 ml of local anaesthetic mixture, if needed during the operation, was applied to the patient using the step-by-step technique, subcutaneously and to the subcutaneous area around the incision, while a maximum of 5 ml was applied under the fascia, around the funiculus (spermatic cord) and to the tissues at the base of the hernia sac. The total amount of anaesthetic used was recorded. Patients who did not have sufficient sensory block despite the application were excluded from the study and general anaesthesia was administered.

In both groups, patients’ intraoperative sedation levels were monitored by Ramsey sedation score (1: Agitated, anxious, 2: Cooperative, 3: Responsive to verbal commands, 4: Brisk response to light glabellar tap or loud auditory stimulus, 5: Sluggish response to light glabellar tap or loud auditory stimulus and 6: No response). If the Ramsey sedation score was <3, sedation was provided with 2 mg of midazolam and additional doses of 2 mg were administered when necessary. Fifty of μg fentanyl was administered in case of intraoperative pain while an additional dose of 50 μg fentanyl was applied providing that inadequate analgesia development was reported by the surgeon. 10 ml/kg of crystalloid infusion was administered to all patients in the S group before the operation to prevent intraoperative hypotension, and 10 ml/kg/h of crystalloid fluid infusion was administered to all patients throughout the operation.

The patients were followed up in the operating room until the end of the operation by routine monitoring with ECG, SPO₂ and non-invasive blood pressure. Intraoperative mean arterial pressure (MAP) and peak HR were recorded at 15-min intervals. Height, weight, gender, ASA, anaesthesia and surgery time and pain scores of both groups were evaluated with the help of Visual Analogue Scale (VAS), with the lowest 0 being the highest,[10] and intraoperative pain scores were recorded at the 6^th, 12^th h and 24^th h [Figure 3].

Figure 3.

Variation of VAS values over time between groups. VAS: Visual analog scale

All the patients underwent Lichtenstein tension-free mesh repair as surgical method. All patients’ operation time from surgical incision to last skin suture, pain-free mobilisation time and oral feeding initiation time, post-operative total amount of analgesics, time for rescue analgesics and surgeon satisfaction level were recorded. 50 mg of diclofenac was administered to the patient intramuscularly given that a VAS value of 4 and above was measured at any time during the post-operative period. If pain persisted, additional 50 mg of diclofenac was administered intramuscularly. Intravenous metoclopramide ampoule was administered in case of nausea or vomiting.

Time to reach discharge criteria was evaluated by the post-anaesthesia discharge criteria (PADSS).[10] Time to reach discharge criteria was accepted as PADSS ≥9.

Post-operative satisfaction level, post-operative wound haematomas, hypotension, nausea, vomiting, urinary retention, headache, tremor, bleeding and wound infection were recorded.

Satisfaction scores were evaluated as 1: Not at all satisfied, 2: Not satisfied, 3: Satisfied, 4: Very satisfied.

Statistical analyses

Statistical analyses were performed using the IBM SPSS (IBM SPSS Statistics, Software version: 22.0, Operating systems: Windows, Chicago, IL, USA) for Windows version 21.0 package program. Numerical variables were expressed as mean ± standard deviation. The normality of numeric variables was evaluated using the Kolmogorov–Smirnov test. The independent’s t-test was used to compare normally distributed variables between the groups. Mann–Whitney U-test was used for the variables in which normality was not achieved. Chi-square test and Fisher’s exact test were used to evaluate the statistical significance between categorical variables. The significance level was accepted as P < 0.05.

G power (Software version: 3.1, Heinrich-Heine-Univ. Düsseldorf, Germany) test was used to determine the sample size. Based on post-operative analgesic consumption in the study of Kamel AA et al., the[11] α error was calculated as 0.05, the power as 0.70, the effect size as 0.8 and the minimum sample size required in both groups as 52.

RESULTS

There was no statistically significant difference between the groups in terms of age, weight, height and gender (P > 0.05). There was no statistically significant difference between the groups in terms of the operated side and pre-operative ASA values (P > 0.05). There was no statistically significant difference in terms of intraoperative SPO2, MAP and pulse values (P > 0.05) [Table 1].

Table 1.

Distribution of demographic features of the groups (n=26)

	Group ESP	Group S	P
Age* (years)	62.42±8.81	61.65±9.34	0.761
Height* (cm)	170.65±5.38	172.96±5.37	0.107
Male/female¶	26/0	26/0	0.592
Weight** (kg)	76.31±13.85	77.27±9.72	0.773
MAP* (mm/Hg)	98.58±9.07	94.77±9.05	0.136
Pulse*	74.69±12.79	74.65±12.37	0.978
ASA¶ (I/II/III)	1/14/11	1/19/6	0.328
SpO2** (%)	95.27±2.20	95.77±1.33	0.402
Side (right/left)¦	15/11	11/15	0.267

*Student’s t-test, **Mann–Whitney U-test, ^¶Pearson’s Chi-square test, ^§Fisher’s exact test. Data presented as mean±SD or number of patients (%). Statistically significant between-group differences (P<0.05). Group ESP: Erector spinae plane block, Group S: Spinal block, ASA: American Society of Anesthesiologists, MAP: Mean arterial pressure, SpO₂: Oxygen saturation, SD: Standard deviation

While the intraoperative VAS value was significantly lower in Group S, the VAS value measured at hour 6 was significantly lower in Group ESP (P < 0.05). Although VAS values at hours 12 and 24 were lower in Group ESP, there was no statistically significant difference (P > 0.05) Table 2.

Table 2.

Post-operative visual analogue scale values among groups (n=26)

Hour	Mean±SD		P
	Group ESP (n=26)	Group S (n=26)
0	1.31±0.92	0.85±1.59	0.017
6th	2.54±1.83	4.69±1.89	<0.001
12th	2.08±2.05	2.96±2.28	0.156
24th	1.23±1.53	1.58±1.50	0.323

Mann–Whitney U-test. Group ESP: Erector spinae plane block, Group S: Spinal block, SD: Standard deviation

In the post-operative period, time to mobilisation, oral feeding and reaching PADSS 9 was significantly shorter in Group ESP, while the waiting time until surgery after the procedure was significantly shorter in Group S.(P < 0.05) Post-operative requirement for rescue analgesics was statistically significantly higher in Group S (P < 0.05). Patients in group ESP exhibited a statistically significant high level of patient satisfaction (P < 0.05). There was no statistically significant difference between the groups in terms of operation time, surgeon satisfaction level and time of first analgesic administration to patients requiring analgesics (P > 0.05) [Table 3].

Table 3.

Durations of mobilization, satisfaction level, waiting, analgesic need (n=26)

	Mean±SD		P
	Group ESP	Group S
Mobilization and feeding start time (h)	1.88±0.55	6.58±2.88	<0.001
Surgical time (min)	35.46±7.96	39.58±10.34	0.125
Rescue analgesic time (h)	6.82±2.63	7.13±4.50	0.951
Post-processing waiting time (min)	29.12±6.16	6.27±1.61	<0.001
Time to reach PADSS 9 (h)	5.31±1.01	19.85±4.05	<0.001
Patient satisfaction level	3.69±0.47	3.15±0.73	0.005
Surgeon satisfaction level	3.73±0.45	3.69±0.47	0.762
Analgesic need, n (%)
Yes	11 (42)	23 (88)	<0.001
No	15 (58)	3 (12)

Mann–Whitney U-test. Group ESP: Erector spinae plane block, Group S: Spinal block, SD: Standard deviation, PADSS: Post-anaesthesia discharge criteria

Intraoperative requirement of midazolam for sedation was significantly lower in Group S, while post-operative requirement of diclofenac was significantly lower in Group ESP (P < 0.05). There was no significant difference between the amount of intraoperative fentanyl use (P > 0.05). In the intraoperative period, the patients in Group ESP required a mean of 5.54 ± 3.71 mg of local anaesthetics. In Group S, no local anaesthetics were administered to any of the patients developing blocks successfully. Urinary retention and shivering, which were recorded as post-operative complications, were significantly more common in Group S (P < 0.05). No statistically significant difference was found between the groups in terms of headache, nausea and bleeding (P > 0.05) [Table 4].

Table 4.

The amount of analgesic and anaesthetic use and complications (n=26)

	Group ESP	Group S	P
Diclofenac (mg)**	21.15±25.19	71.15±42.83	<0.001
Fentanyl (µg)**	21.15±28.89	17.31±24.25	0.703
Midazolam (mg)**	2.46±1.02	1.81±1.05	0.040
Tümescent local anaesthetic (mL)	5.54±3.71	0.00±0.00	<0.001
Urinary retention*
Yes	0	4 (15)	0.037
No	26 (100)	22 (85)
Headache*
Yes	0	2 (8)	0.149
No	26 (100)	24 (92)
Nausea*
Yes	2 (8)	5 (19)	0.223
No	24 (92)	21 (81)
Shivering*
Yes	0	6 (23)	0.042
No	26 (100)	20 (77)
Bleeding*
Yes	1 (4)	0	0.313
No	25 (96)	26 (100)

*Pearson’s Chi-square test, **Mann–Whitney U-test. Data presented as mean±SD or number of patients (%). Group ESP: Erector spinae plane block, Group S: Spinal block, SD: Standard deviation

DISCUSSION

ESP block requires relatively large volumes of local anaesthetics (0.3–0.5 mL kg ^{− 1}) under USG guidance. It has been shown to diffuse from the injection site to vertebral levels 3–6 in the cranial and caudal directions, while its diffusion in the mediolateral direction is limited.[12] It provides somatic and visceral analgesia and anaesthesia in the site of innervation of the nerve it affects due to the spread of local anaesthetic limited to the erector spinae muscle, which encompasses the rib edges and surrounds the thoracolumbar fascia. The spread of local anaesthetic injected from T10 in a volume of 30 ml up to T5 and T12 was demonstrated by magnetic resonance imaging.[13,14]

Inguinal hernia repair surgeries are fairly common but relatively complex procedures. In inguinal hernia repair, innervation of the surgical incision area is mostly provided by the ilioinguinal and iliohypogastric nerves and the anatomical variations in their routes. In addition, some branches of the genitofemoral and lateral cutaneous femoral nerves are also observed to be involved in the innervation of the inguinal region.[15] Motor block formation is not required for the administration of anaesthesia in inguinal hernia repair. Blocking the nerves mentioned above with local anaesthesia can provide necessary intraoperative anaesthesia.

The iliohypogastric nerve originates from the spinal T12 and L1 levels. The ilioinguinal nerve originates from a branch of the L1 spinal nerve. The genitofemoral nerves arise from the upper part of the L1 and L2 spinal nerves. The nerve divides into genital and femoral branches. The lateral femoral cutaneous nerve originates from the L2 and L3 spinal nerves.[16]

In our study, we aimed to diffuse the local anaesthetic between T12 and L3 levels by applying a single injection at the L1 level and a volume of 30 ml for ESP block. In this way, we aimed to provide strong somatic and visceral anaesthesia by blocking the ilioinguinal, iliohypogastric, genitofemoral and lateral cutaneous femoral nerves that innervate the inguinal region.

The local anaesthetic mixture we used in the ESP group consisted of lidocaine hydrochloride, bupivacaine hydrochloride, sodium bicarbonate, adrenaline tartrate and physiological saline. By opting for a mixture instead of a single local anaesthetic, we aimed to; increase the analgesic effect of the local anaesthetic with sodium bicarbonate acting as a buffer,[17] prolong the effect of local anaesthetics by creating epinephrine-induced regional ischaemia and reduce systemic toxicity by preserving it at the injection site,[18] shorten the onset of anaesthesia by using lidocaine, which is a medium-acting local anaesthetic and long-acting bupivacaine together.[19]

In our study, all patients in the EPS group and control group were over 50 years old, with a mean age of 61.53 ± 9.87 years. The reason why we included patients over middle age is because we think that ESP block is especially preferred in middle and advanced aged patients with comorbidities. In our study, the patients in the ESP and spinal anaesthesia groups exhibited similarities in terms of other demographic data, intraoperative haemodynamic measurements and surgical side.

It has been reported that SA induces intraoperative hypotension, for which pre-operative fluid loading provides prevention.[20] In our study, 10 ml/kg of crystalloid was administered pre-operatively to patients in Group S. Therefore, we think that there is no significant difference between the MAP values of the patients in both groups. The reason why we preferred pre-operative fluid loading was to prevent the problems associated with hypotension in the SA group from affecting the results in a false positive way by acting on the intraoperative and post-operative results of our patients in the ESP and S groups.

To date, no formal dose studies have been published for ESP block, but the most common doses are 20–30 ml or 0.2–0.3 ml/kg. The diffusion of local anaesthetics in ESP block is likely to be correlated with volume.[21] For this reason, we used a volume of 30 ml in our study.

We evaluated the VAS score at 6-h intervals in the post-operative period. Various case reports show that the ESP block can be used in abdominal surgeries and provides effective analgesia in the post-operative period. However, most of these studies are not randomised and controlled[22] On the other hand, Tulgar et al.[23] reported that ESP block significantly improved analgesia and reduced opioid consumption following laparoscopic cholecystectomy. Chin et al.[24] showed that ESP block is effective in relieving visceral abdominal pain following gastric bypass surgery in their 3-case report.

In our study, the intraoperative VAS score was higher in the ESP block group, with a mean score of 1.31 ± 0.92 at the beginning of the operation. We preferred to use local anaesthetics when necessary to prevent discomfort that may occur during the incision. The mean use of local anaesthetic per case was 5.54 ± 3.71 ml. Six of the patients in the ESP group did not need to use local anaesthesia. We think that this value can be considered as rather low. It has also been reported that there may be some variations in the innervation of the inguinal region.[15] The relatively higher intraoperative VAS value in ESP block compared to Group S and the need for local anaesthetic use, albeit in low volume, make us think that in some cases, the spread of local anaesthetic may be insufficient to block some branches of the genitofemoral or lateral cutaneous femoral nerves.

The VAS value at the 6^th-h was significantly lower in the ESP group. There was no significant difference between the two groups in terms of VAS values measured at hour 12 and 24. The VAS score in the ESP group was never measured above a mean of 2.54 ± 1.83 in any time period. These results show that ESP block significantly reduces the level of pain in the post-operative period.

It has also been reported that ESP block can be applied easily and safely at the lower lumbar level for pain control in complex regional pain syndrome, and it significantly reduces NRS score and tramadol use.[25] Our study included patients with unilateral hernias and we preferred to use non-steroidal anti-inflammatory drugs instead of opioid analgesia in the post-operative period since the surgery was less invasive and the surgical incision was smaller. No analgesic requirement emerged in 58% of our patients in the ESP group. This rate was only 12% in the SA group. Although the time of rescue analgesics was similar, the total amount of diclofenac use in the post-operative period was significantly lower in the ESP group. These results show us that ESP block significantly reduces the need for analgesics.

One of the main disadvantages of SA in inguinal hernia surgery is delayed mobilisation and delayed oral feeding due to prolonged motor block time and discharge time. Singh et al.[26] reported a significant time of 196.4 ± 21.2 min of motor block time, prolonged first urination time, nausea and vomiting in their study where they used 3 ml of 0.5% hyperbaric racemic bupivacaine in 50 patients undergoing inguinal hernia repair. These factors play an especially important role on the level of patient satisfaction. Since we compared SA with ESP block in our study, we did not measure the duration of motor and sensory blockade. In the ESP group, time to mobilisation and initiation of oral feeding and time to reach PODSS 9 were significantly shorter, while the level of patient satisfaction was higher. Operation time, which is one of the most important factors of surgeon satisfaction, was similar in both groups, and there was no significant difference between surgeon satisfaction levels. In addition, the patients in the ESP group had to wait longer for adequate anaesthesia to occur after the block was applied. We tried to reduce this disadvantage by keeping the patients in the ESP group waiting in the pre-operative preparation room and transferring them to the operating room after sensory blockade.

Khetarpal et al.[27] conducted a study in which they compared paravertebral block (PVB) and SA in inguinal hernia repair with a group of patients similar to our study, and reported that it was associated with less post-operative analgesic requirement, shortened mobilisation time and discharge time, as well as longer block time and surgical anaesthesia in the PVB group without any effect on operation time and MAP levels. These results are consistent with the results we obtained from the ESP group in our study. In addition, urinary retention, headache, nausea and vomiting were more common in the SA group. In our study, urinary retention was significantly higher in the S group, but there was no significant difference in terms of nausea, bleeding and headache.

Spinal anaesthesia inhibits vasoconstriction, which plays an important role in temperature regulation. It also causes a redistribution of core heat to peripheral tissues below the block level. This has been reported to predispose patients to hypothermia and shivering.[28] In our study, it was observed that post-operative shivering was significantly higher in Group S. We did not observe post-operative shivering in any of the patients in the ESP group.

Post-dural puncture headache (PDPH) is especially one of the most unpleasant complications of SA. Xu et al.[29] reported the rate of PDPH as 6.6% in patients in whom Quincke spinal needles were used. In our study, no patients in the ESP group reported headaches while two patients in the S group reported headaches, but there was no statistically significant difference. This ratio is consistent with the ratio reported by Xu et al.[29]

Rani et al.[30] compared SA using 12.5 mg of 0.5% hyperbaric bupivacaine with PVB, and reported high intraoperative fentanyl use in the PVB group. In our study, there was no difference between the amount of intraoperative fentanyl use. We think that this is due to the fact that there was no need for additional intravenous analgesics in the ESP group due to the relief of pain with the local anaesthetics we used, which may occur in some patients due to anatomical variations in the ESP group. Midazolam use was more common in the ESP group. This may be due to the fact that patients in the ESP group are more likely to experience anxiety due to the administration of somatic and visceral analgesia without motor blockade.

This is the first randomised study comparing the effects of SA versus ESP used for intraoperative anaesthesia in inguinal hernia repair.

Limitations

The study was conducted with a limited sample group. Therefore, the power of the study is relatively low. Our study is a single-centre study.

CONCLUSION

ESP block supported by low-dose intraoperative local anaesthetic infiltration for anaesthesia in unilateral inguinal hernia surgeries creates a sufficient level of surgical anaesthesia (non-inferiority) compared to SA. ESP block can also provide less analgesic requirement, early mobilisation, early discharge time, low post-operative pain level, less complication rate and high patient satisfaction in the post-operative period. More randomised controlled studies are needed to conclude that ESP nerve block can be used instead of SA in inguinal hernia repair.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.