Prevention of Post-spinal Anesthesia Hypotension in Caesarean Delivery Using Delayed Supine Positioning

Summary

Participation Requirements

Description

Upon arrival to operating room, Monitors will be applied (electrocardiography - pulse oximetry - non-invasive blood pressure monitor). All measurements will be taken before IV line insertion and premedications. Baseline systolic blood pressure will be obtained in the supine position as the mean of t...

Upon arrival to operating room, Monitors will be applied (electrocardiography - pulse oximetry - non-invasive blood pressure monitor). All measurements will be taken before IV line insertion and premedications. Baseline systolic blood pressure will be obtained in the supine position as the mean of three consecutive readings at 2-minute intervals with a difference of less than 10%. After insertion of a peripheral 18-gauge line with a three way valve for fluids and vasopressor infusion; Premedication's with ranitidine (50mg) and ondansetron (4 mg) will be administered. Subarachnoid block (SAB) will be done in sitting position under complete asepsis in L3-L4 or L4-L5 interspace using 25 g spinal needle. 11 mg of 0.5% intrathecal hyperbaric Bupivacaine and 25um fentanyl will be administered. Block success will be assessed using pinprick or sensation to cold besides adequate motor block. Patients with failed SAB (Defined as sensory level below T4) will be excluded as well as patients with high spinal block (defined as spinal anaesthesia in which spinal denervation extends to second or third thoracic dermatome or sometimes up to cervical dermatomes). Co-hydration will be continued up to a maximum of 1.5 litres (patients with intraoperative blood loss over 1000 ml will be excluded from the study). After delivery of the foetus, oxytocin will be given as an initial bolus of 0.5 IU over five seconds followed by 40 mIU/minute infusion. Inspired air will be supplemented with oxygen 3 l/min via a nasal catheter until delivery. Continuous norepinephrine fixed rate infusion will be given to both groups as 5 mcg norepinephrine bolus at the same time cerebrospinal fluid obtained followed by norepinephrine infusion in a starting dose of 0.05 mcg/Kg/min. Norepinephrine will be prepared as 8 mcg/mL and will be delivered using a syringe pump. Post-spinal hypotension (defined as decreased SBP less than 80% of the baseline reading during the period from intrathecal injection to delivery of the foetus) will be managed by IV ephedrine 9 mg. Severe post-spinal hypotension (defined as decreased SBP less than 60% of the baseline reading) will be managed by IV ephedrine 15 mg. Additional vasopressor bolus was given if SBP did not respond to the first dose within 2 minutes. Intraoperative hypertension (defined as SBP >120% of the baseline reading) will be managed by stopping norepinephrine infusion. The infusion will be resumed when blood pressure returned to its normal value. Intraoperative bradycardia (defined as heart rate less than 55 bpm without hypotension during the period from intrathecal injection to delivery of the fetus) will be managed by stopping the vasopressor infusion. If bradycardia was associated with hypotension, the patient was managed by IV ephedrine 9 mg. If bradycardia persisted after the previous measures, an IV atropine bolus (0.5 mg) will be given. Norepinephrine total dose will be calculated in both groups for comparison purposes. Measurements will be taken every 2 minutes.

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