Clinical utility of change in Carotid artery Corrected Flow time to predict hypotension after spinal anaesthesia in patients with diabetes mellitus.

The diabetic patient scheduled for elective surgery under spinal anaesthesia will be recruited following informed written consent. A thorough preoperative assessment will be done by the attending anaesthesiologist and history of duration of diabetes and current treatment will be obtained. Anthropometric assessment will be done. Routine investigations like RBS, HbA­1c, RFT, CXR and ECG will be reviewed. Premedication and diabetic medications will be prescribed as per department protocol.

 On the day of surgery, after arrival to the operating room, standard ASA monitors such as SpO2, NIBP, ECG will be attached. Ultrasound images of the Right Common Carotid artery in a long-axis view will be assessed using a 12-MHz linear-array probe by an experienced anaesthesiologist (more than 20 carotid scans). The measurement of the flow time would be performed first in supine position (FTc1) followed by 45 degreesleg end elevation (FTc2) with the help of a goniometer. The second reading will be taken after 1 min following leg elevation. The position of the measurement is around 3 cm proximal to the carotid bulb in the longitudinal plane. The cursor angle will be set parallel to the blood flow direction, and the angle of insonation will be set to less than 60 degrees. The Wodey’s formula will be used for the calculation of FTc.

After the FTc measurement, patients will be returned to the supine position. Preloading will be done with 10 ml/kg of Ringer Lactate. Spinal anaesthesia will be performed in the left lateral position using 0.5% hyperbaric bupivacaine 15mg (3mL) administered at L3-L4 level. The level of sensory block will be assessed with the help of Cold touch at 5-minute intervals and the highest level attained will be noted. Hemodynamic parameters will be recorded for 20 minutes from the administration of spinal anaesthesia. Hypotension is defined as fall in systolic blood pressure less than 90 mmHg, or reduction in Mean Arterial Pressure by 20% of the baseline value.

 If any hypotension develops, it would be treated with Inj. Mephenteramine 3 mg boluses. Total vasopressor use for each patient will be noted down. Fall in heart rate to less than 60 bpm will be considered as bradycardia and will be treated with Inj. Atropine 0.12 mg iv.