Rectus Sheath Block Ecacy for Patients Who Underwent Emergency Midline Laparotomy at a Resource Limited Setting in Northcentral Ethiopia, 2019.

Background Midline laparotomy is associated with severe postoperative pain. Literature showed controversial results regarding the ecacy of the rectus sheath block. Objective To assess the effectiveness of rectus sheath block ecacy for patients who underwent emergency midline laparotomy at a resource limited setting in Northcentral Ethiopia, from February 01 to March 30, 2019. Methods This is a prospective cohort study that recruits 60 patients who underwent emergency midline laparotomy. Independent t-test and Manny Whitney tests were used for numeric data while Chi-Square or Fisher exact test was used for categorical variables. P-values < 0.05 were considered as statistically signicant. Results The median (interquartile range) of the numeric rating scale score at the recovery was 3(3-4) for an exposed group and 4.5(3-4.5) for an unexposed group with a p-value of 0.039. Postoperative numeric rating scale scores at 3 rd , 6 th , 12 th , and 24 th hours were statistically signicantly lower in the exposed group. Postoperative tramadol consumption in 24 hours was signicantly lower with a p-value of 0.0001 for the rectus sheath group. Conclusions For surgeries done through midline laparotomy, adding bilateral rectus sheath block (BRSB) at the end of the operation might be an effective postoperative analgesia option.


Introduction
Laparotomies that necessitate midline incisions were commonly accompanied by postoperative pain, typically associated with neuroendocrine stress response [1,2].
Postoperative analgesia enhances early mobilization and decreases the incidence of postoperative chest infection and deep venous thrombosis [3,4]. Administration of multimodal analgesics could limit the excessive use of systemic opioid analgesia and its side effects [3][4][5][6][7]. Good postoperative pain management reduces the wound healing process [8].
Postoperative pain management minimizes the feeling of discomfort and makes the treatment more economic, however, there is no ideal method available for this [9,10].
Schleich rstly described RSB in 1899 aiming at the deposition of local anesthetic (LA) in the virtual space between the posterior wall of the rectus abdominis muscle and its sheath [11]. The anesthetic injected into this space is proposed to spread freely up and down and to block the terminal branches of the intercostals nerves before they leave the rectus sheath [12].
The central portion of the anterior abdominal wall is innervated by the ventral branches of the thoracolumbar nerves, 6th thoracic nerve to 1st lumbar nerve (T6-L1); these ventral branches lie between the rectus abdominis muscle (deep) and the posterior rectus sheath (ventral) and enter the rectus muscle near the midline [13][14][15][16].
The RSB can be performed using a blind technique, with the patient lying supine, a point is identi ed 2-3 cm from midline then passing a short-beveled 5 cm needle through the anterior rectus sheath (a de nitive "pop" should be felt as it passes through) and through the rectus abdominis muscle and the needle is advanced further until a rm resistance of the posterior wall is felt. After negative aspiration for blood, 15-20 ml of local anesthetic is deposited on the posterior wall of the rectus sheath. The procedure is repeated on the opposite side of the midline [17][18][19][20].
The aim of this study is to assess the postoperative analgesic e cacy of the rectus sheath block for emergency midline laparotomy.

Methods
Study setting, design, period and population A Hospital-based prospective cohort study was conducted at Debre Tabor Hospital, in North-central Ethiopia from February 01 to March 30, 2019. The Hospital gives medical, surgical, pediatrics, gynecologic, and obstetrics services. Patients who have undergone emergency midline laparotomy at study setting were the source population while selected patients who underwent emergency midline laparotomy during the study period were the study population. Patients with psychiatric problems, age less than 18, patients who took strong opioids, and patient refusal were excluded.

Sample size determination
The sample size was calculated using the formula for continuous outcomes and means.
Where n = the sample size in each of the groups; X1 = Sample mean in control group; X2 = Sample mean in treatment group; X1 − X2 = the difference the investigator wishes to detect; S 2 = variance; α = conventional multiplier for alpha = 0.05, which is 1.96; β = conventional multiplier for power = 0.80, which is 0.842.
Substituting for these variables yield: n = 31, using a 1:1 ratio between groups a total of 62 patients were required. By adding 5% contingency the total required patients were 66.

Sampling techniques and procedures
Patients who underwent emergency midline laparotomy were recruited into the study by using a systematic random sampling technique. Within 95 patients estimated to undergo emergency midline abdominal laparotomy during the study period, 66 participants were included. The rst participant was selected by the lottery method, then 2 patients for every 3 consecutive patients were included until the required sample size was met.

Operational De nition
Midline Laparotomy abdominal cavity operation through a midline incision of the abdomen, from xiphisternum to symphysis pubis.
Baseline vital sign vital sign before the induction of anesthesia.

Data collection procedures and tools
Data was collected by using a prepared questionnaire starting from intraoperative to 24 hours postoperatively. The severity of pain by using NRS, time for the rst analgesic request (in hours), 24 hours analgesics consumption and incidence of postoperative nausea and vomiting were collected by two anesthetists. Data was gathered at ve-time points: at 0 (immediately at recovery), 3, 6, 12, and 24 hours postoperatively.

Data quality control
Prior to the actual data collection pretest was done on 10% of the sample size to see the effectiveness of the data collecting tool and questionnaire. Collected data were checked for completeness, accuracy, and clarity.
Data processing and analysis Data will be checked manually for completeness, coded and entered into SPSS version 23 computer program. Descriptive statistics were used to summarize data. Chi-square or Fisher exact test was used for

Results
Demographic and Perioperative Characteristics Data were collected from sixty patients with a response rate of 91%. Six patients from both groups were lost to follow up. Demographic data such as age, sex, and ASA status were comparable between the groups (Table 1).

Preoperative vital signs
Preoperative vital signs expressed in the median and interquartile range were comparable between two groups ( Table 2). discrete variables and a student's t-test was used for comparing numerical variables of normally distributed data or Manny Whitney was used for skewed data. A P-value of less than 0.05 was considered as statistically signi cant.

Ethics approval and consent to participate
Ethical clearance was obtained from the Research ethical committee of the College of health science, Debre Tabor University. Con dentiality and the patient's right to withdraw from the study is maintained throughout the study period.

Postoperative vital signs
The postoperative vital signs were taken immediately at the arrival of the recovery room, 6th, 12th, and 24th hours postoperatively were statistically signi cant differences between groups (Table 4). The median NRS score was lower in the RSB group at 0 (immediately at the arrival of recovery room), 3rd, 6th, and 12th hours postoperatively (p-values < 0.05) ( Table 5). Table 5 The median (IQR) Numeric Rating Scale score between the two groups of patients who underwent emergency midline laparotomy in North-central Ethiopia.

Comparison of Total Analgesics Consumption between Groups
There was a statistically signi cant difference in total tramadol and diclofenac consumption within 24 hours postoperatively (Table 6). Table 6 Comparison of total analgesic consumption within 24 hours postoperatively between groups in Northcentral Ethiopia.

Discussion
The International Association for the Study of Pain de ned pain as an unpleasant sensory and emotional experience associated with actual or potential tissue damage or described in terms of such damage [22].
Currently, the important factor that could affect the duration and recovery from postoperative ileus might be decreasing the dose of narcotics [23].
Our study demonstrates that BRSB in patients undergoing emergency midline laparotomy resulted in statistically signi cant lower pain scores when compared with the unexposed group immediately at the recovery room with a median (IQR) NRS score of 1(1-1) versus 6(5-6) p-value 0.0001. The pain severity score in NRS was also lower in the BRSB group at 3rd, 6th, 12th hours postoperatively (p-value < 0.05). Twenty-four hours of analgesics consumption were reduced in the BRSB group (p-value < 0.05).
In line with our ndings, studies showed that BRSB is effective in reducing the severity of postoperative pain score, analgesics consumption and increases time to rst analgesic request [24][25][26][27]. While other studies failed to demonstrate BRSB effectiveness [28,29].
Though there was a proportional difference among the groups for the incidence of postoperative nausea and vomiting, there was no statistically signi cant difference between the groups (p > 0.05) which had a comparable result with a study done by Elbahrawy and El-Deeb (p-value 0.037) [30].

Conclusion
Bilateral rectus sheath block might be an effective and long-lasting analgesic option for midline laparotomy. Ethics approval and consent to participate See methods section.

Consent for Publications
Not applicable.

Con ict of Interest
The authors declare that there is no con ict of interests.