Ultrasound-guided quadratus lumborum block versus ilioinguinal–iliohypogastric nerve block with wound infiltration for postoperative analgesia in unilateral inguinal surgeries: A randomised controlled trial

ABSTRACT

Background and Aims:

Ultrasound (US)-guided quadratus lumborum (QL) block is an abdominal field block that has high efficacy in providing postoperative analgesia for abdominal surgeries. This study was undertaken to compare the US-guided QL block with ilioinguinal–iliohypogastric (IIIH) nerve block and local wound infiltration in unilateral inguinal surgeries, in terms of analgesia and overall patient satisfaction.

Methods:

This randomised controlled trial was conducted in two groups of thirty each. After the completion of surgery under spinal anaesthesia, patients in Group QL received 20 ml of inj. ropivacaine 0.5% while patients in Group IL received 10 ml of inj. ropivacaine 0.5% at the ilioinguinal–iliohypogastric nerve site and 10 ml of inj. ropivacaine 0.5% that was locally infiltrated at the surgical site. Duration of analgesia, Visual Analogue Scale (VAS) score, total requirement of analgesic dosage in the first 24 hours, and patient satisfaction score were compared in both the groups. Statistical analysis was performed using unpaired student’s t test and Chi-squared test with IBM SPSS Statistics version 21 software.

Results:

Duration of analgesia was significantly higher in Group QL (544.83 ± 60.22 min) when compared with Group IL (350.67 ± 67.97 min; P < 0.0001). VAS scores and analgesic requirements were also lower in Group QL. The patient satisfaction score was significantly higher in Group QL (3.93 ± 0.91) when compared to Group IL (3.4 ± 1.0; P < 0.05).

Conclusion:

US-guided QL block significantly prolongs the duration and quality of postoperative analgesia, thereby reducing analgesic consumption and increasing overall patient satisfaction.

INTRODUCTION

Multimodal analgesia, including opioids, non-steroidal anti-inflammatory drugs, and regional anaesthesia (including fascial plane blocks such as transversus abdominis plane [TAP] block, quadratus lumborum [QL] block), is a good approach to managing pain in the postoperative period of surgery.^[1] Enhanced recovery after surgery protocols advise using local and regional analgesia along with intravenous (IV) analgesics to fast-track convalescence periods in daycare surgeries such as inguinal herniorrhaphy.^[2] The role of fascial plane blocks in providing postoperative analgesia following inguinal surgeries has increased with the wider acceptance of ultrasound in anaesthesia practice.^[3] Ilioinguinal–iliohypogastric (IIIH) nerve block requires multiple manipulations of the needle for local anaesthetic (LA) administration. Also, it is devoid of visceral anaesthesia and provides only somatic analgesia. Hence, interest in IIIH nerve blocks has been slowly eroding with the advent of single-site ultrasound (US)-guided blocks.^[4] Recently, the use of QL block in abdominal surgeries has increased due to administration of LA injection at single site and it’s wide anaesthetic coverage.^[5] This block deposits LA within the plane between the thoracolumbar fascia and quadratus lumborum muscle, effectively anaesthetising the nerves (T4 to L2) traversing this plane.

This study aimed to compare the efficacy of US-guided QL block and IIIH block with wound infiltration, with the duration of analgesia being its primary objective. Total analgesic consumption in the first 24 hours, pain assessment in terms of the Visual Analogue Scale (VAS) scores, and patient satisfaction score comprised the secondary objectives.

METHODS

After receiving approval from the Institutional Ethics Committee (BPSGMCW/RC 412/IEC/19) and informed and written consent from patients, this randomised study was conducted on patients who were aged 18–70 years, had American Society of Anesthesiologists (ASA) physical status I–II, and who were undergoing elective inguinal hernia repair surgeries. The study was carried out in accordance with the principles of the Declaration of Helsinki, 2013. The exclusion criteria included patients who refused to participate in the study, patients with recurrent inguinal hernia, patients with known hypersensitivity to LA, patients whose surgery duration exceeded 90 minutes, and patients with major comorbidities such as severe cardio-respiratory illness, morbid obesity, renal ailments, and seizure disorder.

This study was conducted at a tertiary institute over a period of six months, from May 2019 to November 2019. Sixty patients were randomised into two groups (group QL and group IL) using computer-generated random number. Sealed, opaque envelopes were used for concealment of the group allocation. Blocks in both groups were performed by an experienced anaesthesiologist who was well-versed in US-guided procedures, and data was observed by an independent anaesthesiologist who was blinded to the group allocation to avoid observer bias. With standard ASA monitoring, spinal anaesthesia was administered either at L2-L3 or L3-L4 with 3 ml of inj. bupivacaine 0.5% (heavy). The patient was administered a fascial plane block within 15 minutes of the surgery’s completion, as per group allocation. In both groups, a linear array probe of the ultrasonography (USG) machine Sonosite Micromaxx (Fujifilm Sonosite, Bothell, Washington, USA) was used for the identification of structures. A 23-G Quincke spinal needle was used for the administration of blocks through an in-plane approach. In Group IL, patients were laid in the supine position and surgical site infiltration was done with 10 ml of inj. ropivacaine 0.5% by the surgeon, whereas the remaining 10 ml was deposited in the plane between the internal oblique and transverses abdominis muscle after identification of IIIH nerves on the US screen [Figure 1a].^[6] In Group QL, patients were laid in the lateral decubitus position and 20 ml of inj. ropivacaine 0.5% was administered between the posterior aponeurosis of the transversus abdominis muscle and thoracolumbar fascia posterolaterally to the QL muscle, through an in-plane approach from the lateral end of the USG probe [Figure 1b].^[5] One gram of IV paracetamol was injected as analgesic for patients with a VAS score ≥4 or on the patient’s demand, whichever first.

Figure 1.

(a) Ilioinguinal–iliohypogastric nerve block. (b) Quadratus lumborum block

The primary endpoint for determination of analgesic efficacy in both the groups was the duration of analgesia, which was defined as the time interval from the completion of local anaesthetic administration till the demand of first analgesic. The secondary objectives included the determination of the total number of analgesic doses required in the first 24 hours, assessment of VAS scores at predefined intervals (2, 4, 6, 8, 10, 12, 18, and 24 hours), and determining the patient satisfaction score at what point of time. Patient satisfaction score was determined by a five-point Likert scale, with 5 indicating “very satisfied” and 1 indicating “very dissatisfied”. Haemodynamic parameters (systolic and diastolic blood pressure and heart rate) and incidence of adverse effects were also measured in both groups. Block performance time—measured from the beginning of US scan till the end of drug administration—was also observed.

In a study conducted by Sujatha et al.,^[7] a power analysis based on the duration of analgesia, with an a error of 0.05, power of study of 80%, and confidence limit of 95%, expressed that 28 patients in each group would be sufficient to detect a difference in the duration of analgesia at a significant interval of 2.2 hours. Thirty patients were recruited in each group after simple random sampling. Categorical variables were presented in numbers and percentages (%), and continuous variables were presented as mean ± standard deviation (SD). The Kolmogorov–Smirnov test was used to determine normal/skewed distribution, and tests were applied accordingly. Quantitative variables of the two groups were compared using the independent t test. Qualitative variables were correlated using the Chi- square test. A P value < 0.05 was considered significant. Statistical analysis was done using the IBM SPSS Statistics version 21 (IBM, New York, USA) software.

RESULTS

Sixty patients were recruited to participate in this randomised controlled trial [Figure 2]. Both groups were matched for demographic data [Table 1]. Duration of analgesia was significantly longer in Group QL when compared with Group IL (P < 0.0001) [Table 2]. Patients in Group QL had significantly lower VAS scores compared to patients in Group IL during the first 24 hours [Figure 3]. On the first postoperative day, the required number of analgesic doses of paracetamol were significantly lower in Group QL (2.9 ± 0.61) when compared to group IL (3.23 ± 0.63) [Table 2]. Patient satisfaction score after 24 hours was significantly higher in Group QL (3.93 ± 0.91 vs. 3.4 ± 1.0, P = 0.039) [Table 2]. No statistical difference was observed between both the groups regarding haemodynamic variables, time taken to perform the blocks, and the duration of surgery [Table 2]. Postoperative side effects like nausea, vomiting, hypotension, bradycardia, and urinary retention were also comparable in both groups.

Figure 2.

CONSORT diagram

Table 1.

Comparison of demographic data between two groups

Parameter	Group QL (n=30)	Group IL (n=30)
Age (years)	40.80±15.70	43.03±14.42
Weight (kg)	73.60±8.51	76.90±7.06
ASA PS
I	17	14
II	13	16

*Mean±standard deviation, ^#American Society of Anesthesiology Physical Status

Table 2.

Comparison of results between two groups

Parameter	Group QL (n=30)*	Group IL (n=30)*	P
Duration of analgesia (min)	544.83±60.22	350.67±67.97	<0.0001
Number of rescue analgesic dosages (in 24 h)	2.90±0.61	3.23±0.63	0.041
Patient satisfaction score	3.93±0.91	3.40±1.00	0.039
Block performance time (min)	8.55±0.82	8.48±0.89	0.875
Total duration of surgery (min)	54.10±6.01	55.07±6.48	0.563

*Mean±standard deviation

Figure 3.

VAS scores

DISCUSSION

The present study evaluated the analgesic efficacy of US-guided QL block versus US-guided IIIH block and local wound infiltration in unilateral inguinal surgeries. We observed prolonged postoperative analgesia, lower VAS scores, decreased demand for rescue analgesia, and better patient satisfaction.

Following inguinal hernia surgery, multimodal pain therapy (balanced analgesia) is a preferred technique for the management of postoperative pain.^[1,8,9] Use of regional anaesthesia, especially fascial plane blocks, along with conventional oral and intravenous analgesics, results in better outcomes in terms of analgesia and facilitates early mobilisation and recovery.^[2] In our study, inj. ropivacaine 0.5% was used instead of other concentrations, as it provided optimal analgesia and minimised the side effects originating from higher concentrations (0.75%).^[10,11] A significantly longer duration of analgesia was observed in Group QL compared to Group IL. This observation was in agreement with previously conducted studies of Yousef et al.^[12] and Mieszkowski et al.,^[13] both of whom observed similar findings (906 ± 127.2 min and 618 ± 128.21 min, respectively) in US-guided QL block. However, Edward et al.^[14] observed that QL block was equivalent in efficacy to IIIH nerve block. This difference could be attributed to the difference in the drug and its concentration (0.25% bupivacaine). Group QL had significantly lower VAS scores at most periods of observation during the first 24 hours of the postoperative period except at the eighth hour. The discrepancy in VAS score at a specific hour has not been mentioned in other studies and may be due to differences in the analgesic regimen from other studies (use of paracetamol instead of opioids). Although low VAS up to 24 hours was also similar to previous studies conducted by researchers, such as Blanco et al.^[15] and Parras et al.,^[16] we observed in our study that the mean number of analgesic doses required in Group QL were less compared to Group IL, suggesting that US-guided QL block significantly improved the duration and quality of postoperative analgesia. Similar observations have been made in previous studies in which QL block was compared to intravenous anaesthetics or regional nerve blocks.^[17–19]

In our study, the patient satisfaction score was also evaluated in addition to VAS scores, as patient satisfaction is affected by multiple variables like the patient’s expectations, procedure time, associated side effects, and psychological and cultural issues, all of which are not evaluated by the VAS score.^[20] We were unable to proceed with the patient satisfaction questionnaire, such as the quality of recovery score, due to the limited literacy of the patients. Thus, a simpler score was used to assess overall patient satisfaction in patients of rural background. A higher patient satisfaction score was observed in Group QL compared to Group IL [Table 2]. These observations were consistent with studies conducted by Parras et al.^[16] and Öksüz et al.,^[21] both of whom reported higher patient satisfaction scores in patients receiving QL block.

The use of spinal anaesthesia for the conduct of surgery is a limitation of our study, as its effect on QL block and IIIH block cannot be ruled out. However, regional blocks in both groups were administered before the spinal anaesthesia was worn off (within 15 minutes of completion of surgery) to minimise any bias originating due to spinal anaesthesia.

CONCLUSION

US-guided QL block provides longer and more effective postoperative analgesia when compared to US-guided IIIH block with local wound infiltration in unilateral inguinal surgeries.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.