Background

One of the most disturbing complications following surgery is postoperative pain. Opioids, the common analgesic, have many adverse effects as follows: drowsiness, constipation, physical dependence, sedative adaptation, pruritus, respiratory depression, nausea, and vomiting (Woodhouse and Mather 1998). Various methods are used to manage postoperative pain and minimize the usage of narcotics (Ng et al. 2002). Benefits of adequate postoperative analgesia include early ambulation as well as reduction in postoperative pulmonary complications, risk of thromboembolic events, and cognitive dysfunction (McDonnell et al. 2007).

The TAPB was documented for management of postoperative abdominal pain in 1993 by Kuppuvelumani and his colleagues (Kuppuvelumani et al. 1993). The sensory nerves that pass along the anterolateral abdominal wall from T6 to L1 are blocked by TAPB (Almarakbi and Kaki 2014). Three approaches are described to perform ultrasound-guided (USG) TAPB: the subcostal approach, the lateral approach, and the posterior approach, which targets to deposit the local anesthetic in the posterior end of the three muscular layers between the internal oblique and the transversus abdominis muscle. The anterior and lateral cutaneous nerves are blocked in this area from T 9 to T 12 dermatomes (Tsai et al. 2017). The posterior approach gives analgesia for nephrectomies and kidney transplants more effectively than other approaches (Mavarez and Ahmed 2021). In 2007, Blanco provided the first description of the QLB and its effective postoperative analgesia after abdominal surgeries. In the following years, four different techniques for the QLB were introduced: lateral, posterior, anterior (transmuscular), and intramuscular approaches. The anterior QLB block covers the area from T4 to T12–L1 dermatomes, blocking the anterior and lateral cutaneous nerves (Mavarez and Ahmed 2021).

The subcostal incision approach for simple nephrectomy provides adequate exposure and less postoperative pain nephrectomy (Rozen et al. 2008). Blunt dissection of the layer between the renal fascia and the psoas muscle is done. The peritoneum is dissected off the ventral portion of the renal fascia until the renal vein is identified (Chatterjee et al. 2004). According to the subcostal incision of nephrectomy, it is needed to cover the dermatome from T10 to L1, and these dermatomes is covered by both TAPB and QLB (Rozen et al. 2008).

This study aims to compare unilateral USG-QLB with unilateral USG-TAPB in patients planned for open nephrectomy surgeries under general anesthesia (GA), regarding the postoperative analgesic properties; the total postoperative pethidine consumption in the first 24 h; time to first rescue analgesia; postoperative VAS at rest on arrival to the PACU (0 h); after 1 h in the PACU; at , 8, 12, 16, and 24 postoperative hours; and the pethidine-related side effects.

Methods

Eighty adult patients, aged 21–60 years, American Society of Anesthesiologists (ASA) classes 1 and 2, planned for open nephrectomy surgeries with subcostal approach under general anesthesia were enrolled in the study. At the end of the surgery, blocks were carried out by the attending anesthesiologists.

Exclusion criteria included patient refusal, psychiatric illness, coagulopathy disorders or the use of antiplatelets or anticoagulants, thrombocytopenia, hepatic disease, chronic pain, infection at the site of injection, local anesthetics allergy, BMI < 15 kg/m2, or > 30 kg/m2 (Fig. 1).

Fig. 1
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Exclusion criteria

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Patients were divided into 40 patients in each group as follows:

  • Group TAPB (N = 40): Where each patient received a unilateral TAPB in addition to general anesthesia

  • Group QLB (N = 40): Where each patient received a unilateral QL block in addition to general anesthesia

Prior to surgery, each patient was asked for a detailed medical history and underwent a full physical examination. Investigations including coagulation profile, CBC (complete blood count), kidney and liver function tests, and electrocardiography (ECG) were done. The VAS to measure postoperative pain was described to the patients; a mark is written on a horizontal line of a predetermined length of 10 cm to depict a scale where 0 represents no pain and 10 represents the most excruciating pain (Aldrete 1995).

On arrival to the operating room, 5-lead ECG, pulse oximetry, and noninvasive blood pressure (NIBP) were applied. A wide-bore intravenous (IV) cannula was inserted, and IV Ringer’s solution started. Twenty minutes before induction of GA, premedication with 0.02 mg/kg of midazolam IV was given. Induction of GA with fentanyl (2 μg/kg), propofol (2 mg/kg), and then atracurium (0.5 mg/kg) IV was done. Endotracheal intubation with mechanical ventilation was started. Maintenance of anesthesia was done with 1.2% isoflurane in mixture 50% oxygen in air, atracurium (0.1 mg/kg) was given every 30 min, and fentanyl infusion was started at the rate of 1 µg/kg/h (Yousef 2018).

At the end of the surgery and before extubation, patients were divided into 2 equal groups, to receive either unilateral USG-TAPB or unilateral USG-QLB on the side of operation under complete aseptic precautions using a 21-gauge 120-mm Locoplex Sono needle.

Group TAPB (N = 40): Patients received unilateral posterior TAPB. The posterior approach to the TAPB was used. Patients were positioned in the supine position. A linear high-frequency probe covered with a sterile sheath was located in the midaxillary line at the level of the triangle of Petit and moved posteriorly until the TAP was reached. The needle was inserted by an in-plane technique. The bupivacaine was deposited between internal oblique muscles and the transversus abdominis muscle at the posterior end limit of the TAP (Mavarez and Ahmed 2021; Yousef 2018). The correct site of injection was verified by injection of 3-ml normal saline showing hydro dissection between the two muscles, and 0.3 ml/kg of 0.25% bupivacaine was injected in this plane (maximum bupivacaine dose was calculated as 2 mg/kg) (Stav et al. 2016).

Group QLB (N = 40): Patients received unilateral anterior QLB. The anterior approach to the QLB was used (QLB3). In this group, while the patient was still in the lateral position, the convex low-frequency curved probe was covered with a sterile wrap. The probe was vertically positioned above the iliac crest and moved posteriorly until the QL was visualized (Mavarez and Ahmed 2021; Yousef 2018). Bupivacaine was administered into the plane with the needle tip positioned between the psoas major and the QL muscles. The correct site of injection was verified by downward displacement of the psoas major and hydrodissection between the two muscles upon injection of 3-ml normal saline. After confirmation of correct needle position, 0.3 ml/kg of bupivacaine 0.25% was injected into this plane (maximum bupivacaine dose was calculated as 2 mg/kg) (Stav et al. 2016).

After completion of the block, patients were extubated after reversal of the atracurium by neostigmine 0.05 mg/kg and atropine 0.02 ml/kg. Patients were transferred to the PACU for 1 h of observation and then discharged to the ward when reaching a Modified Alderete score of 9 and more (White and Song 1999). In the ward, IV infusion of 1-gm paracetamol was given regular every 8 h. Postoperative rescue analgesia was given for VAS > 3 as 25-mg pethidine IV, to be repeated twice to achieve VAS < 3 at the time of assessment and at any time of patient complaint of pain with a maximum dose of 200 mg/24 h (Accessed on 10/2/2021h https://reference.medscape.com/drug/demerol-meperidine-343315).

Primary outcome

Total postoperative pethidine consumption for the first 24 h in both groups

Secondary outcomes

  • Mean blood pressure (MBP) recorded on arrival to the PACU (0 h), after 1 h in the PACU, and at 4, 8, 12, 16, and 24 postoperative hours in the ward

  • Heart rate (HR) recorded on arrival to the PACU (0 h), after 1 h in the PACU, and at 4, 8, 12, 16 and 24 postoperative hours in the ward

  • Pain assessment at rest by the VAS was started on arrival to the PACU (0 h), after 1 h in the PACU, and continued in the ward at 4, 8, 12, 16, and 24 postoperative hours.

  • Time to first rescue analgesia needed once VAS score reached > 3

  • Pethidine-related PONV

Statistical analysis

Sample size calculation was done according to the study done by Kumar et al. (2020) by community department Ain Shams University. Sample size of at least 30 patients per group achieves 80% power to reject the null hypothesis of zero effect size, when the population effect is 0.08 and the significance level (alpha) is 0.05 using a two-sided sample equal variance t-test.

The data were evaluated using SPSS version 22.0. The mean and standard deviation (SD) or the median and interquartile range (IQR) express numerical data. Frequency and percentage were used to express the qualitative data. The acceptable margin of error was set at 5%, while the confidence interval was set at 95%. Therefore, a p-value of 0.05 or higher was considered significant.

Results

Both groups were comparable regarding the demographic data (age, sex, ASA status, and BMI), with p-values 0.6, 0.64, 0.82, and 0.28, respectively (Table 1). The duration of surgery and the total anesthesia time were comparable between the two groups, with p-value 0.3 and 0.34, respectively (Table 2).

Table 1 Difference between TAP group and QLB group regarding demographic data
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Table 2 Difference between TAP group and QLB group regarding operative and anesthetic duration
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In the current study, the two groups were comparable according to the MBP at 0, 1, 4, 8, 12, 16, and 24 h, with p-values 0.85, 0.7, 0.97, 0.5, 0.9, 0.85, 0.54, and 0.57, respectively (Fig. 2).

Fig. 2
figure 2

Difference between TAP group and QLB group regarding MBP. X-axis for MBP and mmHg for the numbers written, Y-axis for time. Data expressed as mean ± SD or number and p-value. TAP, transverses abdominis plane block; QLB, quadratus lumborum plane block; MBP, mean blood pressure, p-value > 0.05 is considered non-significant

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In the current study, the two groups were comparable according to the HR at 0, 1, 4, 8, 12, 16, and 24 h, with p-values 0.73, 0.97, 0.94, 0.95, 0.93, 0.61, 0.31, and 0.23, respectively (Fig. 3).

Fig. 3
figure 3

Difference between TAP group and QLB group regarding HR. X-axis for HR and bpm for the numbers written, Y-axis for time. Data expressed as mean ± SD or number and p-value. TAP, transverses abdominis plane block; QLB, quadratus lumborum plane block; HR, heart rate, p-value > 0.05 is considered non-significant

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Regarding the total amount of pethidine consumption in the first 24 h, it was found to be statistically significant higher in the TAPB group as compared to the QLB group (115.63 ± 31.87 mg versus 73.75 ± 23.99 mg, respectively), with p-value < 0.001. Time to 1st rescue analgesia was statistically significant prolonged in the QLB group as compared to the TAPB group (477.1 ± 49.2, 430.8 ± 48.1 min respectively), with p-value < 0.001 (Table 3). Regarding the postoperative VAS at rest, patients in the TAPB group had significantly higher median VAS scores compared to those in the QLB group from the time of arrival to the PACU and at 1, 4, 8, and 12 postoperative hours, with p-values < 0.001, < 0.001, 0.0002, < 0.001, and 0.0275, respectively. However, at 16 and 24 postoperative h, both groups showed similar VAS scores with no statistically significant differences (p-values = 0.49, 0.52, respectively) (Table 4).

Table 3 Difference between TAP group and QLB group regarding total pethidine consumption in 24 h (mg) and time to first rescue analgesia (min)
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Table 4 Difference between TAP group and QLB group postoperative pain score
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In the current study, 14 patients (35%) in TAPB group express post operative nausea and vomiting versus 8 patients (20%) in QLB group with p-value 0.13 (Fig. 4).

Fig. 4
figure 4

Difference between TAP group and QLB group regarding complications. Data expressed as proportion, PONV, postoperative nausea and vomiting; TAP, transversus abdominis plane block; QLB, quadratus lumborum plane block, p-value > 0.05 is considered non-significant; p-value < 0.05 is considered significant

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Discussion

Regarding the VAS in the present study, the QLB patients revealed better VAS scores compared to the TAPB patients, from the time of arrival to PACU until 12 postoperative hrs. However, at 16 and 24 postoperative hours, both groups showed similar VAS scores with no statistically significant difference. This was reflected on the total amount of pethidine consumed during the first 24 h, which was significantly higher in the TAPB group as compared to the QLB group. This may be explained by the fact that the QLB covers more dermatomes than the TAPB, has better posterior and cephalad spread, and provides visceral as well as somatic analgesia due to the paravertebral spread (Mavarez and Ahmed 2021; Blanco et al. 2016). According to Blanco, the advantage of the QLB is the local anesthetic spread to the thoracic paravertebral area. This lengthens the duration of analgesia and increases the distribution of the local anesthetic. In aggrement with our study, a meta-analysis done by Xiancun and his colleagues (Xiancun et al. 2020) showed that the QLB analgesia was superior to that by the TAPB at 2, 4, 6, 12, and 24 h with less postoperative consumption of morphine during the first 24 h. Also, in agreement with our study, Blanco and his colleagues (Blanco et al. 2016) reported the superiority of the QLB compared to the TAPB for postoperative analgesia at 12, 24, and 48 h, with patients who received QLB requiring significantly less morphine than those who received TAPB. Also, in harmony with our results is the study done by Yousef (Yousef 2018) which reported lower VAS scores for postoperative pain at 0.5, 2, 4, 6, 12, and 24 postoperative hours, with bilateral QLB compared to bilateral TAPB. Fewer patients in the QLB group required analgesia following surgery, and postoperative morphine consumption was lower. They concluded that QLB offered more efficient postoperative analgesia as compared to TAPB. Another study by Kumar and his co-workers (Kumar et al. 2018) found that postoperative analgesia during abdominal procedures was best managed by QL; it offers statistically significant better pain scores up to 16 postoperative hours than TAPB, with no significant difference in the pain scores at 24 postoperative hours, indicate fading of both blocks. Also, Naaz and his co-workers (Naaz et al. 2021) showed that QLB provided greater pain control than TAPB as evidenced by lower VAS scores at 15 min, 30 min, and 1, 2, 6, 12, and 24 postoperative hours, with longer duration of analgesia was observed in the QLB compared to the TAPB.

Regarding the total amount of rescue analgesia consumed in the first 24 h, the current study recorded significantly higher pethidine requirements in the TAPB group patients compared to the QLB group patients. In agreement with our study, Kolacz and his colleagues (Kolacz et al. 2020) compared the postoperative analgesia of QLB with TAPB in patients undergoing renal transplantation. According to their findings, patients who received QLB needed much less fentanyl in the first day following surgery than those who received TAP block. Contradictory to our results was the study done by Baytar and his colleagues (Baytar et al. 2019), who studied the effect of subcostal TAPB and QLB for postoperative pain relief and found that the dynamic and resting VAS and total analgesic consumption between both groups were without statistically significant difference. However, they reached the conclusion that because subcostal TAPB can be performed quickly and easily, it may be preferred to QLB. This discrepancy between our results and their results may be due to the difference in the type of TAPB used (subcostal approach) as compared to posterior TAPB in our study or possibly because a smaller amount of local anesthetic was used for the bilateral block.

Regarding time to first rescue analgesia, in our study, it was significantly prolonged in the QLB group compared to the TAPB group. In agreement with our study, Malla and his colleagues (Malla et al. 2021) found that the time to 1st rescue analgesia was delayed in the QLB than in TAP; this was reflected on significantly lower analgesic demands at 12, 24, and 48 postoperative hours. Similarly, Kumar and his colleagues (Kumar et al. 2018) found that the time required for 1st rescue analgesia was delayed with QLB as compared to TAPB.

Regarding the hemodynamic specifications observed in the present study, groups were comparable according to the MBP and HR. In harmony with our findings, Naaz and his co-workers (Naaz et al. 2021) and Malla and his colleagues (Malla et al. 2021) reported insignificant hemodynamic changes when comparing both groups.

In the current study, the clinical incidence of PONV was less in patients of the QLB than in patients of the TAPB but without statistical difference. In harmony with our results, Baytar and his colleagues (Baytar et al. 2019), and Xiancun and his colleagues (Xiancun et al. 2020), found that PONV was documented in the TAPB group and in the QLB group without any statistical difference between the two groups.

There were some limitations to our study; the use of patient-controlled analgesia (PCA) may have given more accurate results for the determination of cumulative postoperative opioid consumption than intermittent doses of rescue analgesia. Also, the VAS was not assessed on movement, and time to first ambulation was not assessed and compared in both groups.

Conclusions

The QLB was more efficient in delivering postoperative analgesia after open nephrectomy than the TAPB in terms of postoperative pain scores, total analgesic consumption, and time to first rescue analgesia requirement, with reduction in PONV.