Preoperative ultrasonographic inferior vena cava collapsibility index and caval aorta index in predicting hypotension after subarachnoid block in patients undergoing caesarean section: a prospective observational analytical study

METHODOLOGY

After a detailed pre anaesthetic checkup and a written informed consent, 235 patients undergoing

caesarean section under subarachnoid block will be studied for preoperative ultrasound imaging of the

inferior vena cava collapsibility index and caval aorta index. In the operating room, subarachnoid block

will be administered and when T6 level of sensory block is achieved, surgery shall be initiated. NIBP,

PR, SpO2 measured every min for 5 mins and then every 5 mins throughout the surgery. Episodes of

hypotension shall be noted. Hypotension will be treated with bolus of 5 mg injection ephedrine

(incremental dosing) and bolus of 250 mL of Ringer’s Lactate solution over 10 minutes. Number of

boluses of injection ephedrine and fluid shall be recorded.

WHY IS THIS RESEARCH WORK NECESSARY

Subarachnoid block is preferred over general anaesthesia in caesarean sections due to its relatively safe

maternal and neonatal risk profile. However, in pregnant patients, the incidence of hypotension after

subarachnoid block is more due to various anatomical and physiological changes which can lead to

reduced preload resulting in hypotension. Due to hypotension, there can be many severe adverse

maternal and foetal adverse effects. Therefore, it is essential to assess preoperative intravascular volume

in pregnant patients so that risk of hypotension and its side effects can be avoided.

Preoperative ultrasound guided measurement of IVCCI and CAI can be helpful in assessing

preoperative intravascular volume status accurately and thus may predict hypotension. So, with our

study we aim to assess the efficacy of ultrasound assessment of IVCCI and CAI in predicting

hypotension and also find out the better predictor of post subarachnoid block hypotension.