Comparison of Ultrasoundguided Ilioinguinal Iliohypogastric Nerve Block with Wound Infiltration during Pediatric Herniotomy Surgeries.

BACKGROUND AND AIMS: The purpose of this study was to compare the analgesic efficacy of the ilioinguinal-iliohypogastric nerve block (II/IH) with local wound infiltration in children undergoing herniotomy surgeries.
METHODS: After ethics committee approval and informed consent, 100 children aged 6 months-7 years posted for herniotomy surgeries were randomly divided into Group B and Group W. Local wound infiltration was performed in Group W by the surgeon at the time of port placement and the end of the surgery with 0.2 mL.kg-1 of 0.25% bupivacaine. Ipsilateral II/IH was performed in Group B at the end of the surgery, under ultrasonographic guidance with a Sonosite portable ultrasound unit and a linear 5-10 MHz probe with a 22G hypodermic needle, and 0.2 mL.kg-1 of 0.25% bupivacaine was used on each side. The parameters recorded were postoperative hemodynamics, paracetamol and opioid requirements, postoperative pain scores, postoperative nausea vomiting, and the need for rescue analgesia in the first 6 h postoperatively.
RESULTS: The median pain scores were significantly lower in the II/IH group than the local wound infiltration group at 10 min (2 [0-2.5] compared to 2 [3-4]; P = 0.011), 30 min (1.5 [0-3] compared to 3 [2-5]; P < 0.001), 1 h (1.5 [0-2] compared to 2 [2-3]; P < 0.001) and 2 h (2 [0-2] compared to 2 [1.5-2.5]; P = 0.010) postoperatively. The need for postoperative opioids and rescue analgesia was also significantly lower in the II/IH group (P < 0.001).
CONCLUSION: II/IH is superior to local wound infiltration for postoperative analgesia in pediatric herniotomy surgeries. Copyright:

INTRODUCTION

Regional anesthesia is an essential aspect of modern pediatric anesthesia which provides superior and long-lasting analgesia without the risk of respiratory depression. A promising approach to the provision of postoperative analgesia after hernia surgery is to block the sensory nerve supply to the lower anterior abdominal wall by placing a local anesthetic (LA) between the internal oblique and transversus abdominis fascia blocking the ilioinguinal-iliohypogastric nerves. Ultrasound-guided (USG) ilioinguinal-iliohypogastric nerve block (II/IH) provides excellent pain relief in pelvic surgeries.[12] During the past decade, the use of pediatric nerve blocks has exponentially increased due to the introduction of (LAs) with improved profiles and tools such as ultrasonography that provides better safety and duration of analgesia.[3] The safety advantages of ultrasound over the traditional techniques have not been proven in children because of the limited number of trials.[4]

We aimed to study whether USG-guided II/IH was superior to local wound infiltration for postoperative analgesia for pediatric herniotomy surgeries.

METHODS

After Institutional Ethics Committee approval and informed consent from parents, 100 children in the age group of 6 months–7 years and who belonged to American Society of Anesthesiologists physical status Classes I and II posted for elective hernia repair were enrolled in the study. The exclusion criteria were any contraindication to II/IH, namely surgical scar or distorted anatomy at the site of injection, infection at the injection site, known allergy to LA, and children with known cardiovascular, respiratory, hepatic, or renal disease. Randomization was done using closed envelope technique to divide the patients into two groups to receive either II/IH (Group B) or local wound infiltration (Group W). Allocation concealment was done using sequentially numbered opaque sealed envelopes. The study was carried out in the pediatric surgery operation theater of a tertiary care referral hospital, and the postoperative data were collected in the surgical ward. Induction was done using sevoflurane and intravenous (i.v.) access was established; fentanyl 2 μg.kg−1 i.v. was given after achieving i.v. access. Airway was secured using an appropriate size laryngeal mask airway (LMA). Anesthesia was maintained using a 50:50 mixture of air and oxygen along with sevoflurane. Pressure-controlled ventilation and low fresh gas flows were used. In Group W, local wound infiltration was administered with 0.2 mL.kg−1 of 0.25% bupivacaine by the surgeon at the end of the surgery. In Group B, after skin preparation, II/IH block was performed under ultrasonographic guidance with a Sonosite™ portable ultrasound unit and a linear 8–5 MHz probe. Once external oblique, internal oblique and transverses abdominis muscles were visualized at the level of the midaxillary line 2 cm above and medial to the anterior superior iliac spine, the block was performed using a 22G hypodermic needle and in-plane technique. After negative aspiration for blood, 0.2 mL.kg−1 of 0.25% bupivacaine was administered under direct USG guidance in the space between the transversus abdominis and the internal oblique muscles.

Paracetamol (PCM) 15 mg.kg−1 was administered intravenously to both the groups at the beginning of the surgery. Hemodynamics at 5 min after LMA placement were considered as the baseline. If the heart rate, blood pressure, or both increased by 15% relative to the baseline, 1μg.kg−1 of fentanyl was administered. Pain scores were assessed postoperatively using the face, legs, activity, cry, and consolability (FLACC)[5] scale at 0, 30, and 60 min and 2, 3, and 7 h postoperatively. Heart rate, fentanyl consumption in recovery, PCM consumption in the room and at home, postoperative nausea vomiting, and sleep disturbance were recorded. If the pain score was >4, fentanyl was given as rescue analgesic at a dose of 0.5 μg.kg−1 i.v. in the recovery area and PCM (10 mg.kg−1) in the ward and home. Any adverse effects such as nausea, vomiting, and sedation were noted. The pain scores were noted by an anesthesiologist not aware of the study groups.

Our primary objective was to evaluate the pain scores of patients receiving USG-guided II/IH versus local wound infiltration in the postoperative period. The secondary objective was to evaluate the hemodynamics and the need for analgesics postoperatively.

Statistical analysis [Table 1] of the demographic data such as age and weight was done using Student's t-test, while that data on sex and type of surgery were analyzed using Chi-square test. The continuous outcomes were measured using Student's t-test or Mann–-Whitney U-test. P < 0.05 was considered significant.

Table 1

Statistical analysis

SPSS software version 13
Parameter	Statistical test
Nonparametric quantitative data	Mann-Whitney U-test
Parametric parameters	ANOVA with post hoc Bonferroni’s correction if applicable
Repeated measures	General linear model for repeated measures
Incidence of adverse effects	Chi-square test

P<0.05 was considered statistically significant

RESULTS

Data from 100 patients were analyzed in this study. There was no statistically significant difference in the demographic profile of the two groups with respect to age, sex, and the average duration of surgeries [Table 2].

Table 2

Demographic profile

	Mean±SD		P
	Group W	Group B
Age (months)	35.76±26.69	37.56±25.73	0.59
Weight (kg)	10.39±4.21	10.85±4.02	0.41
Sex	1.28±0.45	1.26±0.44	0.82

P<0.05, statistically significant. SD=Standard deviation

The postoperative heart rates were significantly lower in the II/IH block group at 10, 30, and 60 min compared with the local infiltration group [Table 3].

Table 3

Heart rate

	Group W-wound infiltration			Group B-US guided			P
	Mean	SD	SEM	Mean	SD	SEM
HR induction	109	13	2	108	11	2	0.850
HR at 0 min	116	10	1	110	13	2	0.045
HR at 30 min	69	12	2	67	11	2	0.539
HR at 1 h	112	10	1	102	14	2	0.011
HR at 2 h	109	17	2	100	14	2	0.013
HR at 3 h	110	11	2	101	12	2	0.001
HR at 7 h	110	12	2	99	12	2	0.009

SD=Standard deviation, SEM=Standard error of mean, HR=Heart rate, US=Ultrasound

The postoperative pain scores were significantly lower in Group B at 10 and 30 min and 1 and 2 h than in Group L [Table 4]. After 2 h, the pain scores were similar in the two groups. The need for rescue analgesia was also significantly lower in the II/IH block group when compared with the local wound infiltration group (P < 0.001) [Tables 5 and 6]. The requirement for postoperative opioids and PCM was also considerably lower in the II/IH block group [Tables 5 and 6]. No adverse events such as nausea, vomiting, or sedation were noted in both the groups. In the immediate postoperative period, the mean heart rate in the wound infiltration group was 116.34 ± 10.47, where as in the ultrasound-guided II/IH block group, it was 109.6 ± 12.78. The difference between the heart rates in the two groups was statistically significant (P = 0.004). This difference in the heart rate between the two groups was seen at 1 h or surgery at the postanesthesia care unit (PACU) (P = 0.001). This statistically significant difference in the heart rate indicates better pain relief persisting in the immediate postoperative period in the block group. The heart rate in the ward in both the groups differed at 2nd and 6th h of surgery (P = 0.03 and P = 0.004 at 2nd and 6th h, respectively).

Table 4

Face legs activity cry consolability score at different time interval

FLACC score	Group W	Group B	P
0 min
No pain	6	19	0.00045
Mild pain	12	23
Moderate pain	16	5
Severe pain	16	3
30 min
No pain	13	24	0.084
Mild pain	19	17
Moderate pain	8	5
Severe pain	10	4
60 min
No pain	10	20	0.00001
Mild pain	12	24
Moderate pain	23	3
Severe pain	5	3
2 h
No pain	19	14	0.0002
Mild pain	11	32
Moderate pain	16	4
Severe pain	4	0
3 h
No pain	16	22	0.074
Mild pain	17	22
Moderate pain	13	5
Severe pain	4	1
7 h
No pain	8	20	0.0007
Mild pain	11	27
Moderate pain	26	3
Severe pain	5	0

FLACC=Face, legs, activity, cry, and consolability

Table 5

Postoperative fentanyl consumption

	Group W	Group B	P
0 min	34	8	0.00058
30 min	18	9	0.43
60 min	27	6	0.000075

Table 6

Paracetamol consumption

	Group W	Group B	P
2 h	20	11	0.052
3 h	1	8	0.038
7 h	30	5	0.00005
24 h	22	9	0.096

On arrival to the PACU, 84% of the children of II/IH block group needed no analgesia as compared to 64% of the children in the wound infiltration group, who had no pain to mild pain (P < 0.05). No pain was reported by 82% of the children in II/IH block group as compared to 64% in the wound infiltration group at 30 min postsurgery. Almost 88% of the children in the II/IH block group were pain free at 60 min as compared to 44% in the wound infiltration group. These findings demonstrate that the analgesic efficacy of the II/IH block was better than the wound infiltration.

The reduced requirement of fentanyl in the postoperative period minimized the opioid-related side effects and facilitated early PACU discharge. Only 16% of the children in the II/IH block group required fentanyl as compared to 68% in the wound infiltration group in the PACU immediately after surgery. We observed a similar trend at 30 min after surgery when 18% of the children in II/IH block group as compared to 46% of the children in the wound infiltration group needed fentanyl. We have noticed that in the case of 60-min duration postsurgery, the required fentanyl in II/IH block group was 88% as compared to 44% in the wound infiltration group. After 1 h of surgery in the II/IH block group, 12% of the children consumed fentanyl as compared to 54% of the children in the wound infiltration group.

This difference in FLACC scores persisted in the day care ward also. About 92% of the children had no to mild pain as compared to 60% in the wound infiltration group (P < 0.01) at 2 h postsurgery. No pain was reported by 88% of the children in II/IH block group as compared to 66% in the wound infiltration group at 3 h postsurgery. Almost 94% of the children in the II/IH block group were pain free at 6 h postsurgery as compared to 38% in the wound infiltration group.

We noticed similar trends in PCM consumption in both the groups in the postoperative period. PCM was not required in 68% of the children in the II/IH block group as compared to 40% of the children in the wound infiltration group 2 h after surgery. We noticed that 16% of the children in the II/IH block group were given PCM as against 34% of the children in the wound infiltration group 3 h after surgery. This difference persisted till 7 h of surgery when 60% of the children in the II/IH block group had adequate pain relief and were not given PCM, as compared to 30% of the children in the wound infiltration group.

DISCUSSION

With the advancement in surgical technique and anesthesia, it is imperative that we institute a multimodal approach of analgesia rather than just rely on one modality. II/IH block is a regional anesthetic technique that blocks neural afferents of the lower anterolateral abdominal wall.

In this study, the precise administration of lower volumes of LA under US guidance resulted in an effective II/IH block in children, with a reduced failure rate of 4% and no complications. By post injection US control, Weintraud et al.[6] were able to show that the use of the classic landmark-based approach resulted in only 14% of the injections being made at the correct anatomical location. The overall success rate of the II/IH block was found to be only 61% in this landmark-guided study.

In a prospective randomized study by Willschke et al.,[78] the use of an ultrasound-guided II/IH block was compared with the landmark-based approach concerning efficacy of the two techniques. It was demonstrated that the use of US-guided technique was associated with a significant success rate, as evidenced by a reduced hemodynamic reaction to skin incision (4 compared to 24%) and a reduction in the number of patients needing supplemental analgesia in the recovery room (6 compared to 40%). In a further study by the same authors, they showed that a substantial reduction in the volume of LA (traditionally recommended volume 0.3–0.5 mL.kg−1) is possible when using US guidance. Using a modified up–down technique, they found that an effective II/IH block can be achieved using a volume of LA as low as 0.075 mL.kg−1 when using US guidance.

We observed that the pain scores were considerably lower in the II/IH block group when compared with the local wound infiltration group. Although the difference in the pain scores was small, it was statistically and clinically significant, considering the number of patients receiving rescue analgesia. The postoperative requirement of analgesics was also considerably lower in the II/IH block group.

The intraoperative values of mean heart rate, mean systolic blood pressure, and the mean diastolic blood pressure were comparable in both the groups, indicating that intraoperative analgesic requirements were same in both the groups. This finding avoids the bias of extension of intraoperative fentanyl analgesia in the postoperative period preferentially in any one of the groups.

Abdellatif[9] study demonstrated a decrease in pain scores in the immediate postoperative period in the group that received the II/IH nerve blocks as compared to the caudal block group with no statistically significant difference between both the groups. II/IH block has the advantage of avoiding the central neuraxial caudal block with a lesser dose of LA agent.

Seyedhejazi et al.[10] compared the analgesic effect of caudal and II/IH nerve blockade using bupivacaine-clonidine in inguinal surgeries in children 2–7 years caudal epidural block and II/IH nerve block using bupivacaine-clonidine and concluded that they have comparable effects on analgesia, severity of pain, and hemodynamic changes during and after surgery on inguinal region.

Our study showed that the mean duration of analgesia is longer with the US II/IH nerve block as compared to caudal block with 0.25% bupivacaine. This can be expected that uptake of drug is faster from the epidural space. Casey et al.[11] proved that there are no differences in the postoperative analgesic effects between caudal blocks and II/IHs post orchiopexy. Bhattarai et al.[12] concluded that simplified II/IH nerve blocks in combination with small-volume LA wound infiltration offer longer mean duration of analgesia and better safety margin to start oral analgesics than caudal block with LA alone in children undergoing herniotomy.

II/IH nerve block and i.v. morphine administered following general anesthesia for unilateral orchidopexy in day surgery unit are safe and effective in controlling postoperative pain, but opioid analgesia had a higher incidence of postoperative vomiting and itching[13] II/IH nerve block has an opioid sparing analgesic efficiency as proven by better pain relief scores in the block group.

CONCLUSION

We conclude that ultrasound-guided ilioinguinal-iliohypogastric block can be used in the pediatric age group to provide efficient and safe postoperative analgesia in surgeries of the inguinal area.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.