a b s t r a c t

Background: Serratus anterior plane block (SAPB) was evaluated that in patients with the complaint of rib frac- ture pain in terms of total Analgesic consumption and pain scores.

Method: Sixty patients with rib fracture and NRS (Numeric Rating Scala) pain scores equal or greater than four were included in randomized controlled study. Patients were randomized to perform SAPB or control group. Pri- mary outcome was total tramadol consumption in 24 h. Secondary outcomes were NRS scores (after Patient Con- trollED analgesia (PCA) application 30 min, first, second, 4 th, 6 th, 12 th, 24 th hour), peripheral oxygen saturation (first and 24 th hour after PCA application), chronic pain. and complications.

Results: The total tramadol consumption significantly lower in group S (p = 0.02). NRS scores after 30 min, 1 h, 2 h, 4 h, 6 h, 12 h, and 24 h were significantly lower in group S than in group C (p < 0.001, p < 0.001, p < 0.001, p < 0.001, p = 0.002, p = 0.026). The total number of patients who reported of chronic pain at rest and during effort was significantly lower in group SAPB than in group C (p = 0.006). Nine patients in group C were reported of pain, four of whom had pain at rest and five had pain during effort. One patient in group S was reported of pain during effort.

Conclusion: This study demonstrated that SAPB, as part of Multimodal analgesia in pain management due to rib fractures, is safe and effective in reducing acute pain.

(C) 2020 Published by Elsevier Inc.

1. Introduction

Many patients are admitted to trauma centers because of respiratory and hemodynamic complications and rib fractures pain [1]. Inadequate pain management is a factor that increases respiratory complications in patients admitted with rib fractures [2,3]. Although analgesic use is the First-line treatment for pain due to rib fractures, their effect is often in- adequate, and side effects of opioids, such as respiratory depression, se- dation, nausea, and vomiting, further increase the risk of atelectasis. Among multimodal analgesic techniques, regional analgesia provides effective pain control [4]. Thoracic epidural analgesia (TEA), thoracic paravertebral block (TPVB), Intercostal nerve block (ICNB), intrapleural nerve block, and facial plane blocks are methods of inducing regional anesthesia that are used in rib fractures [5-8].

* Corresponding author at: Department of Anesthesiology and Reanimation, Kahramanmaras Necip Fazil City Hospital, Karacasu Kirim quarter, Kahramanmaras 46050, Turkey.

E-mail address: [email protected] (S. Teksen).

The serratus anterior plane block (SAPB), first described by Blanco in 2013, is a facial plane block that acts on the lateral cutaneous branches of the T2-T9 intercostal nerves, intercostobrachial nerve, nervus thoracicus longus, and nervus thoracodorsalis [9]. The use of SAPB in rib fractures has been reported in patients with rib fractures as an effec- tive analgesic method, but there has been no randomized controlled study in the literature involving patients with rib fracture pain. In this randomized controlled study, we aimed to evaluate SAPB in patients re- ferred to us with the complaint of rib fracture pain in terms of total an- algesic consumption and pain scores.

1. Methods

This prospective controlled randomized trial was approved by the Clinical Research Ethics Committee of Kahramanmaras Sutcu Imam University and was registered in clinicaltrial.gov.tr (NCT04293354).

Patients aged 18-90 years with rib fracture pain (numerical rating scale [NRS] score >= 4) were included in this study between August 2017 and April 2019. Written informed consent was obtained from all participants. Patients were randomized using the closed envelope

https://doi.org/10.1016/j.ajem.2020.12.041 0735-6757/(C) 2020 Published by Elsevier Inc.

method into two groups: S, SAPB-performed group, and C, control group. Patient-controlled analgesia (PCA) with intravenous tramadol was induced in all patients. Patients with an infection at the injection site, coagulopathy, allergy to amide-type local anesthetics, a history of peripheral neuropathy, hepatic or renal failure, lack of consent for the procedure, or lack of cooperation were excluded from the study. The de- mographic data (age, sex, height, weight, ASA class, and rib fracture lo- cation), total analgesic consumption, additional analgesic use, NRS scores (at baseline, 30 min, first, second, 4th, 6th, 12th, 24th h after PCA application), peripheral oxygen saturation (baseline, first, and 24th h after PCA application), chronic pain (three months later), and complications were recorded.

• 1. SAPB application

In the block room, venous vascular access was established from the dorsum of the hand, and the patients were sedated with 1 mg of intra- venous midazolam. Pulse oximetry, electrocardiogram, and non- invasive blood pressure were recorded for the patients, and the block was administered by two anesthesiologists (G.O., S.T.).

All patients were in the supine position and a high frequency (6-13 MHz) linear ultrasound probe (MyLab Five; Esaote, Florance, Italy) was covered with a sterile sheath. After asepsis was provided with povidone iodine, and the probe was placed between the 4th and 5th ribs at the midaxillary line, the latissimus dorsi, serratus anterior, and Intercostal muscles were visualized. Intervention was performed with the “in-plane” technique using an unstimulated 22-gauge, 80- mm, Quinke-type, sonoplex needle (Pajunk, Geisingen, Germany). Over the serratus anterior muscle, 0.5 mL of saline was injected to

allow the fascia to be separated through hydrodissection. After visualiz- ing hydrodissection and performing negative aspiration, 30 mL of 0.25% bupivacaine (Marcaine(R), Eczacibasi) was injected.

• 1. PCA protocol

Intravenous PCA was prepared and provided to all patients. PCA (APM II Ambulatory Pump, Abbott Laboratories, San Diego, CA, USA) was set to be locked-up for 20 min and to administer 10 mg of tramadol in each press at a maximum of 3 times/h, without infusion. PCA was maintained for 24 h in patients, and total tramadol consumptions were recorded.

• 1. Statistical analysis

The approximate sample size was calculated based on the mean postoperative analgesia consumption with PCA using the G*Power 3 (Heinrich-Heine-Universitat Dusseldorf, Germany) program. A pilot study was performed on five patients from each group, and mean tram- adol consumption was calculated based on the value of 196 +- 67.3 in group C and 90 +- 56.74 in group S. We found that approximately 27 pa- tients per group would be necessary to obtain a significant statistical value with a 95% power and 5% significance level for the sample size.

Data were evaluated using the SPSS program for Mac, version 21.0 (SPSS, Chicago, IL, USA). Descriptive data were presented as mean and standard deviation (SD) or median (IQR). The Hodges-Lehman est- imator was used to calculate the 95% CI of the median differences. The effect size was calculated using the cliff delta method. Categorical vari- ables are expressed as the number of cases and percentages n (%).

Fig. 1. CONSORT Flow Chart.

Table 1

Demographic and clinical data

SAPB group (n = 30)

Control group (n = 30)

p-Value

than in group C (p = 0.012, p = 0.008) (Fig. 3). The total number of patients who reported of chronic pain at rest and during effort was sig- nificantly lower in group S than in group C (p = 0.006). Nine patients in group C reported of pain, four of whom had pain at rest and five had

Age (year) 50.7 +- 18.8 42.4 +- 15.8 0.59

Weight (kg) 76.5 +- 12.6 76.2 +- 12.7 0.26

Height (cm) 168.1 +- 9.9 170.7 +- 6.7 0.25

Sex (M/F) 11/19 7/23 0.96

ASA(I/II/II) 14/13/3 7/22/1 0.18

Rib fracture location (P/L/A) 15/5/10 11/10/9 0.31

SpO₂ (Before procedure) 94.6 +- 1.7 95.2 +- 1.4 0.06

ASA: American Society of Anestesiologist Classification, S group: Serratus group, C group: Control group P: Posterior, L: Lateral, A: Anterior, SpO2: Peripheral oxygen saturation, Data are presented as mean +- standart deviation) or numerical p value <0.05 is considered as a statistical.

Fisher’s exact test or ?² test was used to analyze the categorical data. Shapiro-Wilk and Levene tests were used for the conformity of variables to the normal distribution. Group comparisons were performed with the independent-samples t-test for variables with normal distribution and Mann-Whitney U and Kruskal-Wallis tests for variables without a normal distribution. The difference in repeated measurements was an- alyzed using a Friedman test and comparisons with baseline values were performed using the Wilcoxon test, and Bonferroni adjustment was applied.

1. Results

Sixty patients were enrolled in the study, and there was no statisti- cally significant difference between the groups in terms of demographic data or baseline SpO₂ (Fig. 1) (Table 1) (p > 0.05). The total tramadol consumption over 24 h of PCA was 98.33 +- 74.13 and 148.30 +- 87.68 in groups S and C, respectively, showing a significant difference (p = 0.02) (Fig. 2). Two patients in both groups needed additional analgesics. NRS scores at 30 min, the first, second, 4th, 6th, 12th, and 24th h were significantly lower in group S than in group C (p < 0.001, p < 0.001, p < 0.001, p < 0.001, p = 0.002, p = 0.026). When comparing the base- line NRS score with scores at later time points (30 min, 1, 2, 4, 6, 12, and 24 h), pain scores were significantly reduced after 30 min of the PCA ap- plication in both groups. (p = 0.001) (Table 2). SpO₂ values first and 24th hour after the procedure were significantly higher in group S

Fig. 2. Analgesic Consumption, Serratus: Serratus block group, Control: Control group,

*p < 0.05.

pain during effort. Only one patient in group S reported of pain during effort.

1. Discussion

In this study, group S had lesser analgesic consumption, lower pain scores, and lesser chronic pain compared to group C. Epidural, paravertebral, intercostal, intrapleural, serratus plane, rhomboid, and Erector spinae plane blocks are the methods providing effective regional analgesia in rib fractures, reducing analgesic consumption and pain scores [4,8-11]. Carrier et al. reported that patients who underwent an epidural block in rib fractures consumed lesser opioids compared to the control group [12]. Although epidural analgesia is effective, it is less preferred today because of its complication risks and unavailability in coagulation disorders. Khalil et al. reported that SABP maintains good hemodynamic stability compared to TEA in pain management after tho- racic surgery and provides lower pain scores and lesser total Morphine consumption in the early period, without any significant complications [13]. There are no studies comparing SAPB and the paravertebral block in the analgesic management of rib fractures. Saad et al. performed TPVB and SAPB in patients undergoing thoracotomy and compared them with the control group. They reported that analgesia consumption and pain scores were similar in both groups in the first 9 h, and lower pain scores were observed after 12 h in the TPVB group than in the SAPB group [14]. ICNB is an easily applicable block, but multiple and re- peated injections increase local anesthesia toxicity and the risk of pneu- mothorax in patients with multiple rib fractures [15]. SAPB is a more convenient and easier block than ICNB because it affects the lateral cu- taneous nerves and shows efficacy at T2-T9 with a single injection owing to its high volume. Oksuz et al. reported that SAPB is more effec- tive than ICNB in pain management after thoracotomy [16].

Pain due to rib fractures is severe and may progress to chronic pain. Sir et al. found that SAPB administered in posttraumatic rib fractures im- proved chronic pain [17]. In our study, chronic pain was significantly lower in group S. In group C, the pain was relieved and did not develop again in one patient with chronic pain after the application of SAPB upon the patient’s request.

Blanco et al. described two different approaches to SAPB: superficial SAPB (SSAPB) and deep SAPB (DSAPB). They reported that SSAPB was easier to administer and had a longer Duration of action compared to

Table 2

Pain Scores Across Time Points Difference in NRS (C\\S)**

	NRS	S	Control	p	Effect size	Median	95%CI
	0	5.5 [5-6.25]	5[3-6]	0.116	0.20	1	[0-1]
	30 min.	1 [1-2]+	3[2-4]*	< 0.001*	0.59	2	[1,2]
	1 h.	1[1-1]+	3[2-4]*	< 0.001*	0.66	2	[1,2]
	2 h.	1[1-1]+	3[2-4]*	< 0.001*	0.72	2	[1,2]
	4 h.	1[1-1]+	3[2-4]*	< 0.001*	0.67	1	[1,2]
	6 h.	1 [1-2.25]+	2.5[2-4]*	< 0.001*	0.47	1	[1,2]
	12 h.	1 [1-3.25]+	2.5[2-3.25]*	0.002*	0.41	1	[1]
	24 h.	1[1-1]+	2[2-2]*	0.026*	0.29	1	[0-1]
	p1	< 0.001+	< 0.001**

C: Control group, S: Serratus block group,min: minute, h: hour, p: Comparison between groups. p1: Comparison between groups (values are reported as median [IQR], median differance, Mann-Whitney U test, p < 0.05). or 95% CI: Confidence Interval, NRS: Numeric rating scale, effect size values were calculated with cliff’s delta. **Comparison of the base- line value and values at later time points in C (times: 30 min., 1, 2, 4, 6, 12 and 24 h). +Com- parison of the baseline value and values at later time points in S (times: 30 min., 1, 2, 4, 6, 12 and 24 h). Friedman test and the post hoc Wilcoxon Signed Rank Test-p1 values were corrected with Bonferroni (significance criterion p < 0.05/7 = 0.0072).

Fig. 3. SpO₂: Peripheral oxygen saturation, Serratus: Serratus block group, Control: Control group, *p < 0.05.

DSAPB. Furthermore, SSAPB spread to more dermatomes in the anterior, posterior, and lateral planes compared to DSAPB. In a study conducted by Blanco et al., 0.4 mL/kg of 0.125% levobupivacaine affected T2-T6 at minimum and T2-T9 at maximum [9]. In this study, we preferred SSAPB administration. We injected 30 mL of 0.25% bupivacaine into the serratus anterior muscle.

When selecting patient-based regional anesthesia management, the fracture location, number of fractures, and presence of chest tube should be factors influencing the Regional block selection criteria [18,19]. Al- though there is no comparative study of SAPB with other methods in the management of rib fracture pain, TEA, paravertebral block, or ESB may be more effective than SAPB in the management of visceral pain due to Chest tubes [20]. In a retrospective cohort study, Adhikary et al. reported that ESB provided effective analgesia with rare complications and stated that in cases of more than seven rib fractures, the block should be administered from more than one level [21]. This study in- cluded only two patients with more than seven fractures and fractures at T2-T9. When all patients were considered and grouped for rib fracture locations in this study, there were no significant differences be- tween analgesic consumption and pain scores.

To date, no SAPB complications have been reported. It should be con- sidered that Local anesthetic toxicity, pneumothorax, hematoma, and an inadequate or failed block might occur while performing SAPB. In this study, no complications were observed in group S, while nausea and vomiting due to tramadol use were observed in three patients in group C.

• 1. Limitations

First, we did not perform dermatome examinations in our patients after the block. Second, we included all regions in our study without considering the region of fracture (such as anterior, posterior, or lateral).

1. Conclusion

This study demonstrated that SAPB, as part of multimodal analgesia in the pain management of rib fractures, is safe and effective in reducing acute pain and preventing chronic pain.

Financial disclosure

The authors have no financial relationships relevant to this article to disclose.

Funding source

Kahramanmaras Sutcu Imam University Research Foundation - Sci- entific Research Project unit (no:2017/7-184D).

The Clinical Research Ethics Committee of Kahramanmaras Sutcu

Imam University approval obtained (no:2017/11-18) and this study was recorded clinical trial.gov.tr (NCT04293354).

Credit Author Statement

Seyma Teksen: Conceptualization, Methodology, Software, Valida- tion, Formal analysis, Investigation, Resources, Data Curation, Writing- Original Draft, Writing-Review & Editing, Visualization, Project adminis- tration. Gozen Oksuz: Conceptualization, Methodology, Software, Vali- dation, Formal analysis, Investigation, Resources, Data Curation, Writing-Original Draft, Writing-Review & Editing, Visualization, Project administration. Hafize Oksuz: Visualization, Supervision, Data Curation, Resources. Muhammed Sayan: Software, Methodology, Formal analy- sis, Data Curation. Mahmut Arslan: Investigation, Validation, Project administration, Resources. Aykut Urfalioglu: Supervision, Conceptuali- zation, Software, Writing-Original Draft. Gokce Gisi: Software, Writing- Review & Editing, Investigation, Formal analysis. Bora Bilal: Validation, Supervision, Data Curation, Resources.

Declaration of Competing Interest

The authors declare no competing interests to disclose.

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