Comparison of haemodynamic response and phenylephrine requirement following spinal anaesthesia in normotensive and preeclamptic women undergoing caesarean section: a prospective observational study

Source of Data: The study will be conducted in Umaid hospital of Dr. S. N. Medical college and associated group of hospitals, Jodhpur after seeking clearance from institutional ethical committee and obtaining written, informed  consent from the patients.

Study design: Prospective Cohort Comparison

Study Period: 06 months

PRE ANAESTHETIC EVALUATION

Every patient will be subjected to detailed history, thorough physical examination and systemic examination prior to the surgery. Basic demographic data like age, sex, height and weight will be recorded. Routine investigations such as hemoglobin, complete blood count, blood sugar, renal function test, liver function test, blood grouping, cross matching, bleeding time, clotting time, electrocardiography or any specific test will be asked for as per recent guidelines from all the patients. Patients will be explained in detail about the anaesthesia procedure. All the patients planned for elective procedure will be instructed for minimum 6 hours fasting before surgery.

METHOD

After shifting the patients to OT, standard monitoring will be instituited with oxygen saturation (SPO2), 5 lead electrocardiogram (ECG) and baseline parameters like heart rate (HR), systolic blood pressure ( SBP), diastolic blood pressure (DBP), mean arterial pressure (MAP), respiratory rate (RR), SPO2, and ECG will be monitored by using multi parameter monitor.

An 18 G cannula will be inserted in peripheral vein and preloading will be started with crystalloid solution with a dose 10 ml/kg administered over 15 minutes. All patients will be premedicated with Inj ranitidine 50 mg IV and Inj metoclopromide 10 mg IV. All patients in the preeclampsia group will received a 4 g loading dose of intravenous magnesium sulfate (MgSO4) followed by a 1 g/hour infusion for 24 hours for seizure prophylaxis. The IV fluids will be given with the patient in the supine position with a wedge placed under the right hip to obtain a 15° left uterine displacement.

The patient will be then placed in the sitting position, and spinal anesthesia will be administered using 25 gauge Quincke needle at L3-L4  or L4-L5  vertebral interspace using hyperbaric 0.5% bupivacaine 10 mg intrathecally. After free flow of cerebrospinal fluid and negative aspiration of blood, the drug will be injected slowly over 10 sec. Each patient will then placed in the supine position with a left lateral tilt of 15-20 degrees. The height of the sensory block will be assessed using a pinprick test, and a 10°-15° head down-tilt (Trendelenburg position) will initiated if a T4 sensory level  not achieved at 10 minutes after the spinal injection. The surgery will be started once a T10 sensory block will be achieved.

Oxygen will be supplemented by venti mask. The highest dermatomal level of sensory blockade, the time to reach this level, time to achieve total motor blockade, time of start of surgery, delivery of baby, neonatal weight, umbilical cord pH, duration of surgery, side effects or complications will be recorded.

HAEMODYNAMIC MONITORING

All parameters (SBP, DBP, MAP, HR, SPO2, RR, and ECG)  will be recorded before performing spinal anaesthesia and at 2 minute intervals for 30 minutes after the puncture, and then every 5 minutes until the end of the surgery.

Hypotension will be defined as more than a 30% decline in MAP below the baseline in both groups or SBP < 100 mmHg in healthy parturients. Any episode of hypotension will be treated with phenylephrine bolus (50µg).If hypotension persists after one minute, another bolus of phenylephrine will be given. If patient does not respond after 3 boluses, ephedrine 5mg will be given for subsequent treatment. The total amounts of IV administered fluid, and the total doses of phenylephrine and ephedrine will  recorded as well. The largest and lowest value of maternal hypotension and HR from the baseline will also recorded and compared.

Any episode of bradycardia (HR<50 beats/min) will be treated with Inj Atropine 0.6mg bolus. Hypotension associated with bradycardia will be treated using ephedrine from the start rather than phenylephrine. Number and duration of hypotension and total dose requirement of phenylephrine or ephedrine will be recorded.

Side effects like nausea, vomiting will be recorded and treated with Inj Ondansetron IV 4mg. The other study variables that will be included are demographic data; gestational age; spinal puncture to skin incision, skin incision to skin closure, and uterine incision to delivery intervals; the upper sensory level at 10 min after the spinal injection; umbilical cord pH.