Comparision of hemodynamic effect in lateral tilt before and after spinal anesthesia during elective

Comparing the effects of left lateral tilt before versus after spinal anesthesia on the hemodynamic parameters of mothers undergoing elective cesarean section

Controlled, parallel-group, double-blind, randomized clinical trial, phase not applicable on 110 patients. Random Allocation Software was used for randomization.

This clinical trial will be conducted on 110 pregnant women undergoing elective cesarean section at Kowsar Hospital, Urmia. Following random allocation, a 15-degree left lateral tilt will be applied before spinal anesthesia in one group and after it in the other. For blinding, the outcome assessor (who records hemodynamic parameters, is absent during tilt positioning, and is unaware of group allocation) and the data analyst (via coded datasets as groups A and B) are blinded to the intervention; however, the patients and the administering anesthesiologist are not blinded.

Inclusion criteria: Age 18 to 40 years, term singleton pregnancy (37 to 40 weeks), candidate for elective cesarean section, ASA physical status class I or II, and written informed consent. Exclusion criteria: Cardiovascular diseases or chronic hypertension, morbid obesity (BMI > 40), preeclampsia or eclampsia, coagulation disorders or active bleeding, allergy to local anesthetics, and need for general anesthesia.

Group 1: 15° left lateral tilt applied before spinal anesthesia. Group 2: 15° left lateral tilt applied after spinal anesthesia. In both groups, standard spinal anesthesia is performed with 2 mL of 0.5% hyperbaric bupivacaine plus 20 µg fentanyl via a 25G spinal needle at the L3-L4 or L4-L5 interspace.

Systolic blood pressure; diastolic blood pressure; mean arterial pressure (MAP); heart rate; incidence of hypotension; incidence of bradycardia; need for vasopressors

Participants will be allocated to the intervention and control groups using block randomization with block sizes of 4 and 6 on an individual basis. Stratified randomization is not used. The random sequence will be generated using Random Allocation Software. To ensure allocation concealment, sequentially numbered, opaque, sealed envelopes (SNOSE) will be utilized. Upon obtaining written informed consent and arrival in the operating room, the envelope corresponding to the patient’s number will be opened by an individual independent of the principal investigator to determine the intervention type (left lateral tilt before or after spinal anesthesia)

This study is a double-blind randomized clinical trial. Due to the physical nature of the intervention (positioning tilt), blinding the patients and the attending anesthesiologist was not feasible. However, to minimize bias, both the outcome assessor (who recorded hemodynamic parameters without knowledge of group allocation timing) and the data analyst (who analyzed coded datasets as groups A and B) were blinded to group allocations.