Effect of postural changes on inferior vena cava dimensions and its influence on haemodynamics during caesarean section under spinal anaesthesia.

The effect of postural changes on inferior vena cava (IVC) dimensions and its influence on intra-operative haemodynamics in term parturients can be studied using abdominal ultrasound by a subcostal approach. Thirty-two term parturients scheduled to undergo elective caesarean section under spinal anaesthesia were recruited in this observational study. End expiratory diameter and collapsibility index of IVC was measured preoperatively in 3 different positions - supine, recumbent with wedge and left lateral positions. End expiratory diameter was significantly high in recumbent (10.79) and left lateral (12.27) compared with supine (9.96) position (P < 0.0001). A greater fall in systolic blood pressure (>20%) was noted in patients with collapsibility index of more than 11.5 in recumbent with wedge position with a positive predictive value of 86%. IVC dimensions change significantly with change in position and collapsibility index in recumbent position can be a useful parameter for predicting hypotension during caesarean section under spinal anaesthesia.