Operation, Effectiveness, and Limitations of Continuous Serratus Anterior Plane Blocks for Thoracoscopic Surgery in Adults

Figures & data

Figure 1 Flow chart of study.

Notes: Seventy-eight patients were initially assessed prior to surgical operation. Sixty-six patients were enrolled in the present study. During the follow-up to 48 hours after surgery, six patients were excluded because of subcutaneous emphysema postoperatively, low back pain occurred with a history of urinary stone disease, withdrawal as unacceptable nausea/vomiting, refusal of continuing to participation. Finally, data of a total of 66 patients were collected for statistical analysis.

Abbreviations: cSAPB, continuous serratus anterior plane block; PCIA, patient-controlled intravenous analgesia.

Figure 2 Ultrasound-guided cSAPB with placement of catheter. (A) The serratus anterior was above the 4th and 5th ribs and below the latissimus dorsi. (B) The needle indicated by the triangular arrow passed through the latissimus dorsi and serratus anterior, and arrived at the surface of the 5th rib. (C) The catheter indicated by the arrow was inside the serratus anterior muscle plane, surrounded by the drug solution. (D) Over time, the drug distributed adequately into the fascial plane between the serratus anterior muscle and the external intercostal muscle.

Abbreviations: LD, latissimus dorsi; SA, serratus anterior; IM, intercostal muscle.

Figure 3 VAS scores at rest (A) and on coughing (B) in cSAPB and PCIA groups.

Note: Lines represent 95% confidence intervals.

Abbreviations: VAS, visual analog scale; cSAPB, continuous serratus anterior plane block; PCIA, patient-controlled intravenous analgesia.

Figure 4 Survival curve of time to first patients-controlled bolus in cSAPB and PCIA groups.

Note: There was a statistical difference with the time to first bolus between two groups (P=0.007).

Abbreviations: cSAPB, continuous serratus anterior plane block; PCIA, patient-controlled intravenous analgesia.

Table 1 Demographic and Surgical Characteristics of Participating Patients (n=66)

	cSAPB	PCIA	P-value
Sample size, n	33	33
Sociodemographic characteristics
Mean age in years	55.4±10.8	59.6±10.7	0.117
Sex, n (%)			0.135
Male	22 (67)	16 (48)
Surgical characteristics
Mean BMI in kg/m^2	23.5±2.4	23.8±3.3	0.683
ASA Class, n (%)			0.402
II	10 (30)	7 (21)
III	23 (70)	26 (79)
Type of surgery, n (%)			0.415
Lobectomy	25 (76)	22 (67)
Segmentectomy	8 (24)	11 (33)
Mean surgical time in minutes	136.0±42.5	126.3±59.6	0.450
Mean propofol in mg	627.7±124.6	572.6±224.6	0.222
Mean remifentanil in µg	1117.5±273.8	1013.9±475.9	0.283
Median chest tube (IQR), n	1 (1–1)	1 (1–1)	0.558
Hospital stay duration, days	6 (5–6)	6 (6–7)	0.260

Notes: All continuous data are presented as mean±SD or median (interquartile range, IQR) and compared using the independent t-test or the Mann–Whitney U-test, respectively. Categorical data are presented as frequency and analyzed using the chi-square or Fisher’s exact test.

Abbreviations: BMI, body mass index; cSAPB, continuous serratus anterior plane block; PCIA, patient-controlled intravenous analgesia; IQR, interquartile range; ASA, American Society of Anesthesiologists.

Table 2 Outcomes Regarding Pain Management of Patients (n=66)

	cSAPB	PCIA	Δ	P-value
Sample size, n	33	33
AUCVAS-time 1st 24 hours
Mean AUC at rest in cm·h	44.0±17.1	68.9±11.8	24.9	<0.001
Mean AUC on coughing in cm·h	67.1±8.8	78.0±12.5	10.9	<0.001
AUCVAS-time 2nd 24 hours
Mean AUC at rest in cm·h	38.0±16.1	60.4±13.2	22.4	<0.001
Mean AUC on coughing in cm·h	65.5±14.3	75.1±13.3	9.6	0.006
VAS at rest, cm
1st hour	2.0±1.0	3.0±0.8	1.0	<0.001
2nd hour	2.1±1.0	3.1±0.7	1.0	<0.001
6th hour	2.0±0.9	3.2±0.6	1.2	<0.001
12th hour	2.0±0.9	3.0±0.6	1.0	<0.001
24th hour	1.7±0.7	2.8±0.6	1.1	<0.001
VAS on coughing, cm
1st hour	2.7±0.7	3.5±0.6	0.8	<0.001
2nd hour	2.8±0.5	3.6±0.6	0.8	<0.001
6th hour	2.9±0.5	3.6±0.7	0.7	<0.001
12th hour	3.0±0.5	3.4±0.7	0.4	0.014
24th hour	2.9±0.4	3.2±0.6	0.3	0.011

Notes: All continuous data are presented as mean±SD or median (interquartile range, IQR) and compared using the independent t-test or the Mann–Whitney U-test, respectively. Categorical data are presented as frequency and analyzed using the chi-square or Fisher’s exact test.

Abbreviations: cSAPB, continuous serratus anterior plane block; PCIA, patient-controlled intravenous analgesia; Δ, difference in means; AUC_VAS-time, area under the curve of VAS-time.

Table 3 Other Secondary Outcomes of Patients (n=66)

	cSAPB	PCIA	P-value
Mean time to first bolus in hours	15.8±7.6	10.6±8.6	0.011
Bolus press counts, n
Median counts 1st 24 hours (IQR)	2 (0–3)	2 (0–3)	0.478
Median counts 2nd 24 hours (IQR)	0 (0–1)	0 (0–0)	0.349
Rescue analgesia, n (%)	5 (15)	9 (27)	0.232
Nausea/Vomiting, n (%)	2 (6)	12 (36)	0.003
Respiratory depression, n (%)	1 (3)	5 (15)	0.089
Satisfaction, n (%)			0.001
Highly unsatisfied	0 (0)	4 (12)
Unsatisfied	0 (0)	1 (3)
OK	5 (15)	7 (21)
Satisfied	15 (46)	19 (58)
Highly satisfied	13 (39)	2 (6)

Notes: All continuous data are presented as mean±SD or median (interquartile range, IQR) and compared using the independent t-test or the Mann–Whitney U-test, respectively. Categorical data are presented as frequency and analyzed using the chi-square or Fisher’s exact test.

Abbreviations: cSAPB, continuous serratus anterior plane block; PCIA, patient-controlled intravenous analgesia; IQR, interquartile range.