Ultrasound-Guided Posterior Quadratus Lumborum Block for Acute Postoperative Analgesia in Adult Patients: A Meta-Analysis of Randomized Controlled Trials

Figures & data

Table 1 Trial Characteristics

Author/Year	Type of Surgery	Anesthetic Technique	Intervention and Comparison (Number of Participants)	Timing of Block	QLB Block Local Anesthetic	Postoperative Analgesia
Bagbanci 2020^Citation23	Open inguinal hernia repair surgery	0.5% isobaric bupivacaine (SA)	1.QLB (19)	Preoperative	0.25% bupivacaine 20mL	Fentanyl PCIA, bolus 25 µg, lockout 10 mins, loading dose 50 μg, no continuous infusion; IV paracetamol 1 g Q6h
			2.No block (20)
Blanco 2015^Citation17	Caesarean section	15 mg bupivacaine and 20 µg fentanyl (SA)	1.QLB (25)	Postoperative	0.125% bupivacaine 0.2 mL/kg per side	Morphine PCIA, bolus 1 mg, lockout 5 mins, no continuous infusion; oral paracetamol 1 g Q6h and oral diclofenac 50 mg Q8h
			2.Placebo (23)
Bjelland 2019^Citation6	Full abdominoplasty	GA	1.QLB (23)	Preoperative	0.375% ropivacaine 20 mL per side	Morphine PCIA, bolus 1 mg, lockout 5 mins, no continuous infusion; oral paracetamol 1 g Q6h
			2.Placebo (23)
Boulianne 2020^Citation7	Laparoscopic colorectal resection	GA	1.QLB (31)	Preoperative	0.375% ropivacaine 20mL per side	Opioids (with or without patient-controlled devices) and acetaminophen
			2.Placebo (31)
Fujimoto 2019^Citation20	Elective laparoscopic gynecological surgery	GA	1.QLB (29)	Postoperative	0.25% levobupivacaine 25~30mL per side	Fentanyl PCIA, bolus 10 µg, lockout 10 mins, 10 µg/h continuous infusion or non-steroidal anti-inflammatory drugs as needed if pain scores >5
			2.No block (27)
Irwin 2020^Citation15	Caesarean section	10–11.5 mg bupivacaine, 20 µg fentanyl+ 100 µg morphine (SA)	1.QLB+ ITM (44)	Postoperative	0.25% levobupivacaine 20mL per side	Morphine PCIA, bolus 1 mg, lockout 5 mins, no continuous infusion; oral paracetamol 1 g Q6h and diclofenac 75 mg Q12h
			2.No block+ ITM (42)
Ishio 2017^Citation18	Laparoscopic gynecological surgery	GA	1.QLB (35)	Postoperative	0.375% ropivacaine 20 mL per side	Acetaminophen or diclofenac IV Q4h as needed
			2.No block (35)
Ökmen 2018^Citation19	Laparoscopic cholecystectomy	GA	1.QLB (30)	Preoperative	0.25% bupivacaine 0.3 mL/kg per side	Tramadol PCIA, bolus 0.3 mg/kg, lockout 20 mins, a demand dose of 10 mg; 1 g paracetamol Q8h if pain scores >5
			2.Placebo (29)
Salama 2020^Citation14	Caesarean section	12.5 mg of 0.5% bupivacaine and 10 µg fentanyl (SA)	1.QLB (30)	Postoperative	0.375% bupivacaine 24 mL per side	Morphine PCIA, bolus 1 mg, lockout 5 min, max dose 48 mg/4 h, no continuous infusion; IV paracetamol 1 g if pain scores >3
			2.Placebo (30)
Tamura 2019^Citation16	Caesarean section	11–13 mg bupivacaine and 10 µg fentanyl ± 100 µg morphine (SA)	1.QLB+ ITM (34)	Postoperative	0.3% ropivacaine 0.45 mL/kg per side	Oral diclofenac sodium 50 mg as needed if pain scores <3; IV pentazocine 15 mg with pain scores 3–5.9; IV acetaminophen 15mg/kg and pentazocine 15 mg if pain scores >6
			2.Placebo+ ITM (38)
			3.QLB (36)
			4.Placebo (38)
Pangthipampai 2021^Citation12	Caesarean section	0.5% hyperbaric bupivacaine 2–2.2 mL + 200 µg morphine (SA)	1.QLB+ ITM (18)	Postoperative	0.25% bupivacaine 25 mL per side	Morphine PCIA, bolus 1 mg, lockout 5 mins, no continuous infusion; oral acetaminophen 1 g Q6h and ibuprofen 400 mg Q8h
			2.Placebo+ ITM (20)
Li 2021^Citation21	Laparoscopic renal surgery	GA	1.QLB (32)	Preoperative	0.4% ropivacaine 30 mL	Sufentanil PCIA, bolus 5 µg, lockout 10 mins, 0.625 µg/h continuous infusion
			2.No block (32)
Borys 2021^Citation13	Caesarean section	0.5% hyperbaric bupivacaine 1.8–2.6 mL (SA)	1.QLB (35)	Postoperative	0.375% ropivacaine 0.2 mL/kg per side (up to 20 mL)	Morphine PCIA, bolus 1 mg, lockout 5 mins, no continuous infusion; IV paracetamol Q6h; IV morphine 5 mg if pain scores >4
			2.Placebo (33)
Zhu 2021^Citation22	Laparoscopic radical gastrectomy	GA	1.QLB (30)	Preoperative	0.3% ropivacaine 20 mL per side	Sufentanil PCIA
			2.Placebo (29)

Abbreviations: QLB, quadratus lumborum block; ITM, intrathecal morphine; PCIA, patient-controlled intravenous analgesia; IV, intravenous; GA, general anesthesia; SA, spinal anesthesia.

Figure 1 Flow diagram.

Table 2 The GRADE Level of Certainty for Main Outcome

Outcomes	No of Studies	No of Patients	Quality Assessment					Effect SMD (95% CI)	Quality	Importance
			Risk of Bias	Inconsistency	Indirectness	Imprecision	Other Considerations
Rest pain scores at 6 h	8	509	No serious	Serious^a	No serious	No serious	None	SMD −0.59 (−1.05, −0.12)	Moderate	Critical
Rest pain scores at 12 h	6	355	No serious	Serious^a	No serious	Serious^b	None	SMD −0.83 (−1.47, −0.19)	Low	Critical
Rest pain scores at 24 h	11	686	No serious	Serious^a	No serious	No serious	None	SMD −0.37 (−0.71, −0.03)	Moderate	Critical
Dynamic pain scores at 6 h	4	291	No serious	Serious^a	No serious	Serious^b	None	SMD −0.33 (−0.79, 0.12)	Low	Critical
Dynamic pain scores at 12 h	5	300	No serious	Serious^a	No serious	Serious^b	None	SMD −0.93 (−1.52, −0.33)	Low	Critical
Dynamic pain scores at 24 h	9	571	No serious	Serious^a	No serious	No serious	None	SMD −0.52 (−0.93, −0.11)	Moderate	Critical
Opioid consumption at 6 h	3	190	No serious	Serious^a	No serious	Serious^b	None	SMD −0.43 (−0.87,0.01)	Low	Critical
Opioid consumption at 12 h	2	134	No serious	Serious^a	No serious	Serious^b	None	SMD −0.13 (−1.08,0.82)	Low	Critical
Opioid consumption at 24 h	8	453	No serious	Serious^a	No serious	No serious	None	SMD −0.45 (−0.86,-0.03)	Moderate	Critical

Notes: ^aQuality was rated down for inconsistency because I2>50%. ^bQuality was rated down for imprecision due to total population size is less than 400.

Abbreviations: SMD, standard mean difference; CI, confidence interval.

Figure 2 Risk-of-bias summary.

Abbreviations: “+”, low risk of bias; “?”, unclear risk of bias; “-”, high risk of bias.

Figure 3 Forest plot of postoperative rest pain score. (A) Rest pain scores at 6 h after surgery. (B) Rest pain scores at 12 h after surgery. (C) Rest pain scores at 24 h after surgery.

Figure 4 Forest plot of postoperative dynamic pain score. (A) Dynamic pain scores at 6 h after surgery. (B) Dynamic pain scores at 12 h after surgery. (C) Dynamic pain scores at 24 h after surgery.

Figure 5 Forest plot of opioid consumption. (A) Opioid consumption at 6 h after surgery. (B) Opioid consumption at 12 h after surgery. (C) Opioid consumption at 24 h after surgery.

Figure 6 Forest plot of postoperative nausea and vomiting.

Table 3 The Result of Subgroup Analysis

Outcomes	Subgroup	No of Trails	No of Patients	Effect SMD/RR (95% CI)	P	I^2
Rest pain scores at 6 h	General anesthesia	3	174	SMD −0.83 (−1.66, 0.00)	0.05	86%
	Spinal anesthesia	5	335	SMD −0.44 (−1.01, 0.13)	0.13	84%
Rest pain scores at 24 h	General anesthesia	4	244	SMD −0.87 (−1.65, −0.09)	0.03	88%
	Spinal anesthesia	7	442	SMD −0.08 (−0.27, 0.01)	0.39	0%
Dynamic pain scores at 24 h	General anesthesia	2	129	SMD −1.50 (−1.89, −1.10)	<0.00001	0%
	Spinal anesthesia	7	442	SMD −0.24 (−0.52, 0.03)	0.08	52%
Opioid consumption at 24 h	General anesthesia	4	225	SMD −0.20 (−0.49, 0.10)	0.19	21%
	Spinal anesthesia	4	228	SMD −0.76 (−1.61, 0.10)	0.08	89%
Postoperative nausea and vomiting	General anesthesia	4	228	RR 0.78 (0.51, 1.19)	0.25	0%
	Spinal anesthesia	2	94	RR 0.15 (0.02, 1.15)	0.07	0%

Abbreviations: SMD, standard mean difference; CI, confidence interval; RR, risk ratio.

Figure 7 Forest plot of rest pain scores at 24 h after surgery by subgroup.

Abbreviations: GA, general anesthesia; SA, spinal anesthesia.

Figure 8 Begg’s funnel plot of rest pain scores.

Notes: (A) Funnel plot of rest pain scores at 6 h after surgery; (B) Funnel plot of rest pain scores at 12 h after surgery; (C) Funnel plot of rest pain scores at 24 h after surgery.

Figure 9 Begg’s funnel plot of dynamic pain scores.

Notes: (A) Funnel plot of rest pain scores at 6 h after surgery; (B) Funnel plot of rest pain scores at 12 h after surgery; (C) Funnel plot of rest pain scores at 24 h after surgery.

Figure 10 Begg’s funnel plot of opioid consumption.

Notes: (A) Funnel plot of rest pain scores at 6 h after surgery; (B) Funnel plot of rest pain scores at 12 h after surgery; (C) Funnel plot of rest pain scores at 24 h after surgery.

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