Impact of serratus plane block on pain scores and incentive spirometry volumes after chest trauma

Figures & data

Table 1 Patient demographics

Variable	Value
Age, years, Median (Interquartile Range)	57.5 (49, 72)
Weight, kilograms, Median (Interquartile Range)	82 (68, 95)
Male sex, n (%)	21 (62%)
Number of ribs fractured, Median (Interquartile Range)	7 (6, 9)
Length of Hospital Stay, days, Median (Interquartile Range)	11 (7, 16)

Figure 1 Ultrasound image of the chest wall – the ribs and pleura are identified. Tilting the ultrasound probe allows for visualization of the border between ribs, intercostal, serratus anterior, and latissimus dorsi muscles to allow for proper placement of local anesthetic and/or catheter.

Table 2 Baseline clinical variables and change from baseline in pain score, incentive spirometry (IS) volume, respiratory rate, and pulse oximetry (difference between post-serratus plane block [SPB] value and baseline value).

	N=34	P-value
Measurements before SPB
Pain score	7 (6, 9)
IS volume	700 (400, 1000)
Respiratory rate	24.5 (18, 30)
Pulse oximetry	0.96 (0.94, 0.98)
Measurements after SPB
Pain score	3 (0, 4)
IS volume at 4 hrs	850 (590, 1125)
IS volume at 24 hrs	775 (500, 1000)
IS volume at 48 hrs	1000 (500, 1100)
Respiratory rate	16 (14, 19)
Pulse oximetry	0.99 (0.98, 1.00)
Measurements change from baseline
Pain score	−5 (−7, −3)	<0.001
IS volume at 4 hrs	150 (50, 250)	<0.001
IS volume at 24 hrs	100 (40, 250)	<0.001
IS volume at 48 hrs	170 (50, 500)	0.001
Respiratory rate	−5.5 (−11, −3)	<0.001
Pulse oximetry	0.02 (0, 0.05)	<0.001

Notes: Continuous values are summarized as median (IQR). Wilcoxon signed rank test was used to evaluate change from baseline in pain score, IS volume, respiratory rate, and pulse oximetry. Bonferroni adjusted P-values were calculated to control the overall type I error of six tests

Figure 2 Pain scores–pain scores before and after SPB are depicted by boxplot. Changes in pain score (N=33) were analyzed by the Wilcoxon signed rank test. Bonferroni adjusted correction was applied to control the overall type I error of six comparisons. P-value is <0.001.

Abbreviation: SPB, serratus plane block.

Figure 3 IS before and 4 hrs, 24 hrs, 48 hrs after SPB is depicted by boxplot. Changes in IS from baseline (N=28, 25, 21 for 4, 24, and 48 hrs, respectively) were analyzed by the Wilcoxon signed rank test. Bonferroni correction was applied to control the overall type I error of six comparisons. P-values are <0.001 at 4 and 24 hrs. P-value at 48 hrs is 0.001.

Abbreviations: IS, incentive spirometry; SPB: serratus plane block.

Figure 4 Respiratory rates before and after SPB are depicted by boxplot. Changes in respiratory rate (N=34) were analyzed by the Wilcoxon signed rank test. Bonferroni correction was applied to control the overall type I error of six comparisons. P-value is <0.001.

Abbreviation: SPB, serratus plane block.

Figure 5 SpO2 before and after SBP is depicted by boxplot. Changes in SpO2 (N=34) were analyzed by the Wilcoxon signed rank test. Bonferroni correction was applied to control the overall type I error of six comparisons. P-value is <0.001.

Abbreviation: SPB, serratus plane block.