Effects of Ropivacaine Concentration on Analgesia After Ultrasound-Guided Serratus Anterior Plane Block: A Randomized Double-Blind Trial

Figures & data

Figure 1 CONSORT flow diagram.

Figure 2 Ultrasonogram of serratus anterior plane block.

Abbreviations: LD, latissimus dorsi muscle; SA, serratus anterior; LAs, local anesthetics; R4, the fourth rib; R5, the fifth rib.

Table 1 Demographic and Intraoperative Characteristics

Characteristic	R0.375	R0.5	R0.75	P-value
	(n=20)	(n=20)	(n=20)
ASA classification(I/II)	13/7	15/5	16/4	0.556
Age, y	43.5(8.5)	41.0(14.8)	39.0(9.6)	0.449
Height, cm	158.7(4.3)	158.2(4.0)	159.0(4.2)	0.809
Weight, kg	58.8(8.0)	60.0(7.5)	58.2(6.3)	0.859
BMI, kg/m^2	23.3(2.8)	23.8(2.7)	23.1(2.9)	0.746
Surgical duration, min	58.3(12.0)	61.5(15.6)	57.8(13.4)	0.646
SAP block duration, h	7.8(2.3)	11.0(3.3)	13.9(4.0)	<0.001

Note: Measured data with normal distribution were expressed as mean (standard deviation).

Abbreviations: ASA, American Society of Anesthesiologists; BMI, body mass index; SAP, serratus anterior plane.

Figure 3 (A) AUC of NRS pain intensity scores at rest through 24 h postsurgery; (B) AUC of NRS pain intensity scores on movement through 24 h postsurgery. (C) NRS score (ranging from 0 to 10) for pain at rest; (D) NRS score (ranging from 0 to 10) for pain on movement. Values are mean (standard deviation) or median (interquartile range), n=20. R0.375: 0.375% ropivacaine with 20mL volume; R0.5: 0.5% ropivacaine with 20mL volume; R0.75: 0.75% ropivacaine with 20mL volume. ^#P<0.05 indicates a significant difference in comparison to Group R0.375. *P<0.017 indicates a significant difference in comparison to Group R0.375.

Abbreviation: NRS, numerical rating scale.

Figure 4 (A) the worst pain scores (ranging from 0 to 10); (B) the incidence of moderate-severe pain (NRS>3). Values are median (interquartile range) or percentage, n=20. R0.375: 0.375% ropivacaine with 20mL volume; R0.5: 0.5% ropivacaine with 20mL volume; R0.75: 0.75% ropivacaine with 20mL volume. *P<0.017 indicates a significant difference in comparison to Group R0.375.

Abbreviation: NRS, numerical rating scale.

Figure 5 The time of first need for tramadol. Kaplan-Meier survival curves demonstrated that the time between completion of surgery and the first administration of rescue analgesia. R0.375: 0.375% ropivacaine with 20mL volume; R0.5: 0.5% ropivacaine with 20mL volume; R0.75: 0.75% ropivacaine with 20mL volume. There was no significant difference among the three groups, P =0.180.