Brief Summary

Type of study: Prospective Observational Study.

Inclusion criteria:

1)     Age 18 yrs and above.

2)     Patients presenting for below umbilical or lower limb surgeries under spinal anaesthesia.

Exclusion criteria:

1)     Patient refusal.

2)     Coagulation disorders (international normalised ratio or activated partial thromboplastin time ratio > 2.5, platelet count < 10⁶ / µL).

3)     Allergy to local anaesthetic.

4)     Infection at the site of spinal anaesthesia.

 Methodology:

After approval from Institute’s Ethics committee, a prospective cohort study will be planned on patients scheduled to undergo elective surgery under spinal anaesthesia. The patients included will be of American Society of Anaesthesiologists (ASA) physical status grade I or II and aged between 18 to 80 years. It will be observed that written informed consent is taken from every patient, prior to the surgery. After collection of data the patient’s cohort will be created depending upon the IVC compressibility:

Group A: IVC compressibility  < 50%.

Group B: IVC compressibility  > 50%.

It will be observed that the pre anaesthetic check-up (PAC), routine blood and other investigations of need are properly carried out. Standard monitoring of electrocardiography (ECG), pulse oximetry, blood pressure, respiratory rate, axillary skin temperature and end tidal carbon dioxide are attached, along with it, an intravenous (i.v.) infusion of Lactated Ringer’s solution is started prior to shifting the patient in operation theatre.

An independent observer will note the IVC diameter using high frequency 2D Echocardiography (2D ECHO) probe in sub xiphoid region. IVC is visualised as hypoechoeic structure, whose diameter varies with respiration. IVC diameter will be observed under M-mode, at 1 cm caudal to opening of hepatic vein, as visualised under 2D ECHO. IVC is normally 1.5 to 2.5 cm in diameter when measured 1 cm caudal to opening of hepatic vein. Diameter of IVC less than 1.5 cm suggests volume depletion and IVC diameter greater than 2.5 cm suggests volume overload. In spontaneously breathing patients, IVC collapsibility index will be noted under M-mode of 2D ECHO using following equation:

IVC collapsibility index = [(Maximum IVC diameter) - (Minimum IVC diameter)]

[Mean IVC diameter]

Once the IVC collapsibility index is noted, as done routinely the patient will be shifted to operation room (O.R). The observer who has noted the IVC collapsibility index will not accompany the patient in the O.R. Inside the O.R. an independent observer who is a part of the study will note the vitals (heart rate and blood pressure) prior to giving spinal anaesthesia and after giving spinal anaesthesia, the readings will be noted at an interval of 5 minutes.

Inside O.R, the observer will note the incidence of hypotension, amount of fluid given as bolus and the amount of vasopressor (phenylephrine) required.

The patients in both the cohort groups will be similar in respect to their age, ASA physical status and type of surgical procedure done.