Comparing Sitting Versus Lateral Position During Spinal Anesthesia on the Severity of Hypotension:

Source Population: All parturients who are scheduled for elective cesarean delivery under spinal anesthesia at Dessie Comprehensive Specialized Hospital

Sample size determination: This is the first study comparing siting and lateral positioning during the initiation of spinal anesthesia and no previous study was done in the study area. So the sample size is determined from a previous study done by Atashkhoei Simin et al.in Dubai in the same population with a reported incidence of hypotension of 50% in the lateral group and 76.6 % in a sitting position. Using G*Power (using version 3.1.9.2) with a power of 90%, confidence interval of 95%, and a ratio of treatment to control 1:1, it is estimated that 120 participants and considering dropping out and nonresponse (10% contingency) a total of 132 patients (66 in each group) would be needed. the investigators chose this paper because a large sample size was obtained using the G*Power application.

Sampling procedure A 7-month log book report showed 392 patients undergoing elective c/s. 120 patients will be recruited with a probability of 33% until the sample size is achieved by considering the sequential patients scheduled for C/S as the sampling frame. All patients have a 50% equal chance of being included in the study. The first patient will be recruited by lottery method and then every 3rd will be included until the required sample size is completed. After informed consent taken, eligible participants will be allocated to one of the two groups with a sealed non-transparent envelope containing the name of the study group.

Data collection procedures Three anesthetists will be trained by the principal investigator about how to collect the data for 10 days. The data collectors will explain the study and take written consent from each patient if they agree to participate in the study. Then the patient's fluid intake will be restricted and will run at 20ml/kg /hr.NS at the time of identification of cerebrospinal fluid as a co-loading via an 18-G intravenous Catheter. The study drug or placebo will be given 5 minutes before the spinal block. After applying the minimum standard monitoring like NIBP, ECG and pulse oximetry baseline HR and BP readings will be taken in the left lateral position, with the cuff positioned at the level of the heart. Then spinal anesthesia will be performed by a responsible anesthetist (who is blinded for the study) between L3-L4 interspace by using tuffurs line as a landmark with a 24 gauge spinal needle. After the free flow of cerebrospinal fluid (CSF), 12.5 mg of 0.5% isobaric bupivacaine (2.5 ml) and both groups of parturient will positioned supine with 15 degrees of left lateral tilt. Patients' socio-demographic data (age, sex, weight, BMI,), ASA, type of procedure, total amount of IV fluid, and duration of surgery will be recorded using a structured questionnaire. MAP and HR will recorded at 0 (baseline), 5, 10, 15, 20, 30, 40, 50, and 60 minutes intra-operatively in both exposed and unexposed groups. The requirement for vasopressors, antiemetic and anti-shivering like tramadol or pethidine will be studied during 15 intraoperative period and immediate postoperatively. Collected data will be checked for completeness, accuracy, and clarity by the principal investigator.

Blinding

The data collector and primary investigators will be blinded for the position of parturient.

The data collector will enter the OR after the spinal block is done. Random numbers which will be generated by computer software for all study participants will held in sealed envelopes until the day of surgery. On the day of surgery after they change clothes the mother will pick up the envelope that will opened by one anesthetist who will be responsible for writing the generated random number and letter as S for the Sitting group and L for the lateral position group by marker on the questioners.

Data quality management

Training will be given to data collectors regarding study tools, objectives of the study, rights of respondents, and confidentiality of the information. To ensure the quality of data, it will be checked out for completeness, accuracy, and clarity before data entry. The complete data will be entered into the SPSS version 22 computer program. Data clean-up and cross-checking will before analysis.

Data processing and statistical analysis

Data will be checked, coded, entered, and analyzed by SPSS version 22 computer program.

The normality of data will be checked by the Kolmogorov-Smirnov (K-S) test, histogram, Q-Q plot, box plot, kurtosis, and skewness. The presence of Outliers will also assessed by boxplot. Student t-test and Mann-Whitney test will be applied to compare continuous numerical variables of normally distributed and skewed data respectively. Statistical differences between groups for categorical data will analyzed using the Chi-squared test. Frequency, percentages, tables, and figures will be used to summarize data. Data will expressed in terms of mean ± SD for normally distributed data or median (inter quartile range) for skewed data. A P-value less than 0.05 is considered as statistically significant.