Anaesthesia to a parturient requires highest degree of care because the anaesthesiologist has to look after two individuals, the mother and foetus. 

Hypotension during spinal anesthesia for caesarean delivery can have detrimental effects on both mother and neonate. 

After spinal anesthesia, the following parameters have been found to be risk factors for hypotension: sensory height block, baby weight, duration between spinal induction and skin incision, baseline systolic blood pressure, and anesthetistexperience.  

These effects include decreased utero placental blood flow, impaired foetal oxygenation with asphyxial stress and foetal acidosis and maternal symptoms of low cardiac output such as nausea, vomiting, dizziness and decreased consciousness.  

Careful positioning with left uterine displacement and volume preloading with crystalloids or colloids has been used to prevent it, but these are not complete measures and vasopressor is required to correct hypotension .

Hypothyroidism has been known to be associated with diastolic hypertension. hypothyroid patients have significantly increased diastolic blood pressure. Restoration of euthyroidism with thyroxine administration significantly reduces the systolic and diastolic blood pressures in these patients.

Clinical manifestations of hypothyroidism affecting anaestheticmanagement are reversible myocardial dysfunction, reversible defects in hypoxic and hyper carbic ventilatory drives, obstructive sleep apnoea, paraesthesia, increased cerebrospinal fluid protein concentration, hyponatremia, anaemia, abnormal coagulation profile, increased peripheral nociceptive thresholds and coronary artery disease.

Decreased intravascular volume, preload, cardiac output and blunted baroreceptor response make the patient sensitive to cardio depressant effects of General anaesthetics.

Regional anaesthesia is favoured over general anaesthesia. Hypothyroidism is associated with qualitative platelet dysfunction, epidural hematoma is a theoretical risk and presence of normal coagulation is confirmed before regional anaesthesia. 

In this study we observe whether Hypothyroidism contributes to excessive post spinal hypotension in caesarean sections and also the requirement of vasopressor drugs in its management.

Elective surgery: T. Ranitidine 150 mg PO and T. Metaclopramide 10 mg PO with sips of water 2 hrs before surgery.

Emergency surgery: Inj. Ranitidine 50 mg IV and Inj. Metaclopramide 10 mg IV 30 min before surgery.

In the operation theatre appropriate equipment for airway management and emergency drugs are kept ready. Patients will be shifted to the operation theatre. The horizontal position of the operating table checked. 

The patients are made to lie supine with a pillow under head. 

Monitors - non invasive sphygmomanometer, ECG and pulse oximetry monitor. 

Intravenous access - 18 G IV cannula. Ringer lactate solution started at 15ml/kg

The anaesthesiologist unaware of the patient’s history will perform the subarachnoid block and note the observations in all the patients involved in the study. 

Patients are placed in right lateral position. 

Skin over the back was prepared with antiseptic solution and draped with sterile towel. 

The L3-L4 interspace will be identified and 26 G Quincke-Babcock needle isintroduced in this space through a midline approach. 

Once the needle pierced the dura and is in the subarachnoid space, free flow of CSF is verified and 10 mg (2ml) of 0.5% Heavy Bupivacaine +  100 mcg of Morphine(0.1 ml) is administered intrathecally. The patients are turned supine and immediately a wedge is placed under the right flank. 

Oxygen is administered at a rate of 6 lit/min by a face mask. 

Inj. Oxytocin 3 U in 5% Dextrose is given over 30 seconds after clamping the cord. Successive doses are repeated every 3 minutes as required. Intravenous fluids were administered at a rate of   ml / hr throughout the surgery. 

Heart rate, Systolic BP, Diastolic BP, MAP and SPO2 are recorded and taken as baseline value. The same parameters are monitored every 2 minute till 30 mins and thereafter every 5 minutes till the end of surgery. 

Whenever Hypotension (Fall in Systolic BP < 20 % from baseline value or systolic BP < 90 mm Hg) occurred Vasopressor bolus of Inj Phenylephrine 25mcg will be given . 

The time of onset of hypotension after SAB, lowest systolic BP recorded, total no. Of boluses and total mg of vasopressor used are recorded. 

Bradycardia (HR < 60 / min) is noted and is treated with Inj. Atropine 0.3 mg IV bolus. 

The highest level of sensory block is assessed by pinprick method 5 min after SAB. 

The subarachnoid block-delivery interval will be recorded. 

Neonatal outcome is assessed by the paediatrician by APGAR score at first and fifth min. 

The incidence of nausea and vomiting is noted. 

Total intravenous fluids given and urine output is also noted.