Application of Ultrasound-Guided Ilioinguinal/Iliohypogastric Nerve Block in Pediatric Same-Day Surgery

Abstract

The aim of this study was to evaluate the safety and efficacy of ultrasound-guided ilioinguinal/iliohypogastric nerve block (IINB) in pediatric patients undergoing same-day inguinal region surgery. Ninety patients aged 4–6 years, ASA levels I–II, were randomly divided into three groups: U, T, or C (n = 30 each). After basic anesthesia, patients in group U underwent ultrasound-guided IINB, those in group T underwent traditional Schulte-Steinberg IINB, and those in group C (controls) received intravenous anesthesia (ketamine-propofol) only. Patients who remained sensitive to intraoperative stimuli received additional intravenous doses of 1 mg/kg ketamine. Heart rate (HR), mean arterial pressure (MAP), and oxygen saturation (SPO₂) were recorded upon entering the operating room (T0), at skin incision (T1), while pulling the hernia sac (T2), during skin closing (T3), and upon awakening (T4) at recovery. HR and MAP at T1, T2, and T4 were higher in group C than those in the other two groups, and recovery time in group C was significantly prolonged (P < 0.05). Group U required significantly lower quantities and frequency of ketamine injection, and pain scores in group U during awakening were lower than those in the other two groups (P < 0.05). Ultrasound-guided IINB provided an improved nerve block effect and postoperative analgesia, reduced the amount of local anesthetic required, facilitated more rapid postoperative recovery, and was a safe and effective method of anesthesia.

Introduction

Increasing emphasis has been placed on pediatric same-day surgery, and the proper method of anesthesia is one of the factors that may influence the outcome for patients [1]. The anesthesia plane in sacral anesthesia is not sufficient to encompass the inguinal region, and its efficacy is poor for same-day inguinal surgeries in children over the age of 3, and in these patients, epidural anesthesia must be carried out in the setting of general anesthesia, which may have greater potential for complications. A regional block can meet the demand for anesthesia and postoperative analgesia with less physiological stress for the patient, and it can offer the benefit of more rapid postoperative recovery. Ilioinguinal/iliohypogastric nerve block (IINB) is applicable to inguinal region surgery in children, but because of the difficulty of accurate anatomic positioning and the limitations of traditional fascial click techniques that rely on the subjective detection of a loss of fascial resistance, 35–75 % of pediatric patients will require additional analgesics [2]. Catheter positioning aided by anatomic landmarks during traditional methods of IINB based on fascial click or nerve stimulation techniques may result in sub-optimal block effects because the majority of punctures will fail to provide accurate positioning for the local anesthetic injection, thus prohibiting adequate infiltration of the area surrounding the nerve tissue. In recent years, ultrasound technology has been regarded as a gold standard for nerve localization in clinical anesthesia [3] and ultrasound guidance has become widely used in peripheral nerve block. Davarci et al. [4] have confirmed in outpatient knee arthroscopy patients that ultrasound guidance for sciatic and femoral nerve block may provide better anesthesia effect with fewer complications than unilateral spinal anesthesia, and Amiri et al. [5] have reported that ultrasound-guided brachial plexus block can be safe and effective during upper extremity operations in children under 6 years of age. Ultrasound-guided IINB has also been found to be more effective than conventional fascial click methods [6]. The aim of the present study is to evaluate the safety and efficacy of ultrasound-guided IINB in surgeries of the inguinal region in pediatric patients.

Materials and Methods

Patients

Ninety patients who were scheduled for selective unilateral inguinal surgeries (including high ligation of the hernia sac and high ligation of hydrocele of the tunica vaginalis), aged 4–6 years old, weighed 15–22 kg, and belonged to ASA levels I–II according to the admission data were randomly divided into three groups (n = 30 each): group U, the ultrasound group; group T, the traditional group; and group C, controls. All operations were performed by the same group of surgeons. Patients with coagulation abnormalities, respiratory infection, and/or allergies to local anesthetic were excluded. This study was conducted in accordance with the Declaration of Helsinki. This study was conducted with approval from the Ethics Committee of Zhengzhou University. Written informed consent was obtained from all participants’ guardians.

Anesthesia

All children were fasting for 6 h preoperatively, fasting water for 2 h, and were given midazolam 0.5 mg/kg orally 30 min before the operation. After arriving in the operating room, all patients were monitored by electrocardiogram tracings and blood pressure, pulse, and oxygen saturation (SPO₂) measurements. Intravenous access was established, and mask oxygen was administered. The basal anesthesia for all patients in all groups consisted of intravenous injection of 0.01 mg/kg penehyclidine plus 2 mg/kg hydrochloride ketamine plus 2 mg/kg propofol. Ultrasound-guided IINB was performed in group U using a desktop color Doppler (Shenzhen Mindray Bio-Medical Electronics Co., Limited by Share Ltd., model DC-6). Using a previously described method [7], the procedure was performed within 1 min by two anesthesiologists who have had ample experience with nerve blocks under ultrasound guidance in children. Briefly, the long axis of the ultrasound probe was positioned near the anterior superior iliac spine with one end pointing to the umbilicus so that the ultrasound image displayed the three layers of low-echo abdominal wall muscles—obliquus externus abdominis, obliquus internus, and transversus abdominis—from top to bottom, allowing visualization of the ilioinguinal nerve (IIN) and the iliohypogastric nerve (IHN) as two hypoechoic oval structures between the internal oblique and the transversus abdominis that were characterized by an internal low-echo shadow surrounded by an external high-echo shadow. After sterile preparation of the skin at the puncture site, the needle was advanced vertically along the long axis of the probe until it was accurately positioned around the nerves within the internal oblique/transverse abdominal muscle gap, and a 0.2 mL/kg mixture of 0.8 % lidocaine with 0.25 % levobupivacaine (Batch No. 1171208002; Run Du Min Tong Medicine Co., Ltd., Zhujiang, China) was injected following aspiration without blood. The distribution of the local anesthetic was observed on real-time ultrasound, and if it was determined that the anesthetic was not being distributed around the neural structures, the needle was repositioned for repeat injection. In group T, traditional landmark-based IINB was performed within 30 s by two experienced anesthesiologists using the Schulte-Steinberg method [8]. In brief, the puncture point was located below the anterior superior iliac spine with a depth to the inguinal ligament of about 5–10 mm, depending on the patient’s height. The needle was advanced slowly until the disappearance of resistance (fascial click) which indicated piercing of the external oblique aponeurosis. After aspiration without blood, the local anesthetic combination described above was administered between the internal and external abdominal oblique muscles at a dose of 0.3 mL/kg. A 22-gauge small-bevel 44-mm needle with an injection extension tube was used in both groups. Patients in group C received intravenous ketamine, 1 mg/kg, during pre-incision skin preparation. Patients in all the three groups received a continuous intravenous infusion of propofol, 2–6 mg/kg/h, and if a patient was sensitive to operative stimuli, additional doses of 1 mg/kg ketamine were provided. Manually assisted ventilation was provided as needed, and any children who required endotracheal intubation with mechanical ventilation during surgery were excluded from the study. All patients were sent to the recovery room postoperatively.

Data Collection

Heart rate (HR), mean arterial pressure (MAP), and SPO₂ were recorded successively upon entering the operating room (T0), at skin incision (T1), during pulling of the hernia sac (T2), during skin closure (T3), and upon awakening in the recovery room (T4). In patients who required additional intraoperative ketamine doses, the frequency and amounts of drug required were recorded. Operative time and recovery time were also recorded, and the face, legs, activity, cry, consolability (FLACC) behavioral tool was used for postoperative pain scoring by an anesthesiologist who was not participating in the study. Pain scores were recorded at awakening and at 2 and 4 h after surgery. A score of >3 was considered a sign of inadequate analgesia, and in these cases, the patient was given 0.15 g paracetamol by rectal suppository. Paracetamol requirements were recorded by a nurse who was not involved in the study. Adverse events including nausea, vomiting, urinary retention, and itching during and after surgery were also recorded.

Statistical Analysis

Using SPSS 13.0 software, all measurements were expressed as mean standard ± deviation, intra-group comparisons were performed by repeated measures analysis of variance, comparisons among groups were performed by single factor analysis of variance, and results were compared using the chi-square test, with P < 0.05 representing statistically significant differences.

Results

Patients

The groups had no statistically significant differences in gender ratios, age, body weight, height, type of operation, and operation time (P > 0.05), as shown in Table 1.

Table 1.

Comparison of the general information and the situation at surgery ($\overline{x}\pm s$, n = 30)

Items	Group U	Group T	Group C
Sex ratio (male/female)	22/8	21/9	22/8
Age (years)	5.3 ± 1.1	5.2 ± 1.0	5.2 ± 1.2
Body mass (kg)	18 ± 2	19 ± 3	18 ± 3
Height (cm)	111 ± 8	113 ± 11	112 ± 10
High ligation of hernia sac (cases)	20	20	21
High ligation of hydrocele of tunica vaginalis (case)	10	10	9
Operation time (min)	18 ± 5	17 ± 4	18 ± 4

Heart Rate, Mean Arterial Pressure, and Oxygen Saturation

HR and MAP at T1, T2, and T4 were significantly lower in groups U and T than in the control group (P < 0.05) (Table 2).

Table 2.

Comparison of intraoperative HR, MAP, and SPO₂ of the children in the three groups ($\overline{x}\pm s\overline{x}$, n = 30)

Index	Group	T0	T1	T2	T3	T4
HR (time/min)	U	101 ± 10	99 ± 13*	102 ± 12*	101 ± 10	103 ± 12*
	T	102 ± 9	98 ± 11*	101 ± 11*	99 ± 12	101 ± 10*
	C	100 ± 9	112 ± 12#	115 ± 16#	101 ± 13	113 ± 13#
MAP (mmHg)	U	72.6 ± 6.8	69.7 ± 7.1*	70.7 ± 7.6*	71.7 ± 8.1	70.9 ± 8.0*
	T	71.1 ± 8.9	70.2 ± 6.8*	71.4 ± 8.1*	71.9 ± 7.6	72.1 ± 7.7*
	C	69.7 ± 7.2	79.4 ± 5.8#	79.7 ± 7.4#	72.4 ± 8.3	79.6 ± 8.9#
SPO2 (%)	U	97.9 ± 0.8	98.4 ± 0.5	99.3 ± 0.4	98.3 ± 0.5	99.2 ± 0.4
	T	98.0 ± 0.6	99.1 ± 0.8	98.7 ± 0.6	99.2 ± 0.6	98.6 ± 0.7
	C	98.5 ± 0.6	98.5 ± 0.7	99.4 ± 0.6	98.4 ± 0.6	98.7 ± 0.4

*P < 0.05, comparison with C; ^# P < 0.05, comparison with T0

Additional Ketamine Dose, Recovery Time, and Postoperative Pain Scores

The size and frequency of additional ketamine dose was significantly lower in group U compared to those in groups T and C (P < 0.05), while recovery times in group C were significantly longer than those in the other two groups (P < 0.05). The pain score at awakening was lower in group U than that in groups T and C, and only one patient (3 %) in group U required paracetamol suppository, compared to 8 patients (27 %) in group T and 13 (43 %) in group C (P < 0.05) (Table 3).

Table 3.

Comparison of the dose and frequency of intraoperative ketamine added again, recovery time, and postoperative pain score ($\overline{x}\pm s$, n = 30)

Groups	The times of adding ketamine time	The dose of adding ketamine dose (mg/kg)	Recovery time (min)	Postoperative pain score
				Awaking time	2 h after operation	4 h after operation
U	0.4 ± 0.2	0.4 ± 0.2	11 ± 5	1.1 ± 0.5	1.0 ± 0.3	0.8 ± 0.4
T	0.8 ± 0.3*#	0.7 ± 0.3*#	12 ± 7	2.3 ± 1.2*#	1.1 ± 0.4	0.9 ± 0.2
C	1.4 ± 0.6*	1.7 ± 0.8*	21 ± 6*	4.2 ± 1.1*	1.2 ± 0.7	0.9 ± 0.3

*P < 0.05, comparison with group U; ^# P < 0.05, comparison with group C

Adverse Events

One patient in group T sustained vascular puncture during needle insertion for the nerve block, and two patients in group C had vomiting during recovery. No other adverse events were reported during or after the operation.

Discussion

Fear and anxiety are often present during the perioperative period in children, particularly in preschool-age patients who are unable to fully cooperate in the operation and will usually require general anesthesia. Non-tracheal intubation allowing spontaneous respiration with ketamine-propofol intravenous anesthesia as a routine protocol for pediatric ambulatory surgery cases has unique advantages, but the depth of anesthesia is not easy to master. Too deep anesthesia may cause respiratory depression, and too light anesthesia may cause intraoperative motion by the patient that could affect the operation, while general anesthesia alone is not conducive to postoperative analgesia. In the present study, the group that did not undergo preoperative nerve block (group C) required higher doses of intraoperative intravenous anesthesia, had prolonged recovery times, and included an increased proportion of patients who required paracetamol for postoperative analgesia.

IINB is useful for pediatric inguinal surgeries, including inguinal hernia and hydrocele, as well as for postoperative analgesia. In China and abroad, there are three traditional methods of choice for guiding the puncture [8]: the von Bahr method (1979), the Sethna and Berde (1989) method, and the Schulte-Steinberg method (1990). Therefore, this method was used in the present study for IINB in group T. Although the traditional anatomic landmark-guided (fascial click) IINB techniques have the advantage of simplicity, the success rate of these blocks has only been about 70 %. These techniques also involve greater risk of perforation of the colon and small intestine [9] and pelvic hematoma [10]. Furthermore, the IIN and IHN often exhibit anatomic variations in the inguinal region. Al-dabbagh [11] examined the IIN and IHN in 110 adults undergoing inguinal hernia repair and found that the structures described in textbooks accounted for only 41.8 % of those actually observed, while the remaining 58.2 % had variability. Such variations may contribute to reduced success rates of traditional IINB techniques.

In recent years, ultrasound technology has been applied for nerve block techniques [12]. Thallaj et al. [13] reported high success rates, good anesthesia effects, and high patient satisfaction with ultrasound-guided obturator nerve block, and Bhoi et al. [14] achieved satisfactory effects with ultrasound-guided nerve block for limb trauma in emergency patients. Thomas et al. [15] showed that the ultrasound-guided interscalene brachial plexus block was safe and effective and that the time to onset of the sensory and motor block was shorter than that in blocks performed using a nerve stimulator. Research on ultrasound-guided nerve block has also confirmed that increased accuracy of injection permits smaller doses of local anesthetic at the block site without reducing anesthetic potency. The recommended local anesthetic dose for regional anesthesia by IINB in children is 0.3–0.5 mL/kg [16–19]. In the present study, the local anesthetic dose in group U was 0.2 mL/kg, which was lower than that used in group T (0.3 mL/kg) and reduced the possibility of local anesthetic toxicity. Because ultrasound-guided nerve block was more accurate, the lower anesthetic dose did not affect the anesthetic potency, as indicated by the lesser intraoperative ketamine requirement in group U compared to the other groups. Reducing the dose of local anesthetic can reduce other potential side effects as well. Transient femoral nerve block is a common complication of pediatric IINB that can delay postoperative return to activity and result in worry for children and their parents [20, 21]. It is generally believed that transient femoral nerve block correlates with anesthesia dose, and diffusion of a large dose of local anesthetic may also cause a prolonged lower extremity block and urinary retention. Willschke et al. [6] have pointed out that the IIN and IHN are very close to the peritoneum, with an average distance of 3.3 mm and a shortest distance of 1 mm, and it must also be emphasized that there is a greater risk of perforation of the peritoneum during a blind puncture, while an ultrasound-guided procedure can directly detect neural and vascular structures, determine a clear puncture tract for the needle, and show the distribution of the local anesthetic, contributing to reduced doses and improved success rates. Ultrasound guidance can also reduce the risk of intravascular injection, nerve damage, and other adverse events. Yang et al. performed selective unilateral inguinal region operations with ultrasound-guided vs. traditional IINB in 100 children and showed that the success rate of the ultrasound-guided nerve block was superior to that of the traditional method and was safe and effective, which is consistent with the results of the present study.

To summarize, IINB under ultrasound guidance improved the analgesic effect of anesthesia during surgery, reduced the required dose of local anesthetic, was associated with more rapid recovery after operation, and was a safe and effective method of anesthesia for pediatric patients undergoing same-day surgeries of the inguinal region.