Perfusion Index as a Predictor of Hypotension Following Sub-arachnoid Block Among Patients Undergoing Lower Segment Caesarean Section

Overview

C-section is one of the commonly performed surgical procedures. During this surgical procedure the surgeon cuts into uterine cavity through abdominal wall and takes out the baby. This is done by by making the lower half body of the patient numb by injecting local anesthesia drugs into the space surrounding the spinal cord. This allows the mother to remain awake and immediately bond with the baby once it gets delivered. Also this technique provides effective pain relief both during and after the surgery. However like any other technique or drug it is associated with a number of side effects. The most important being fall in blood pressure. There are numerous ways to treat it. However if one is able to predict fall in blood pressure before administration of anesthetic technique one can easily prevent it. One of the recently discovered novel way to predict fall in blood pressure is Perfusion index which is calculated by Pulse oximeter. It is a device use to check amount of oxygen in blood and heart rate. Perfusion index refers to the total amount of blood present in the limbs of the person. Once we administer drug in the space surrounding the spinal cord the amount of blood in the limbs increases while the amount returning to heart decreases which ultimately results in less amount of blood being pumped out by heart resulting in fall in blood pressure. Therefore theoretically those individuals who have a high baseline Perfusion index will more likely to develop low blood pressure. This study aims to identify the cut off value of perfusion index to predict fall in blood pressure.

Spinal anesthesia is employed to provide excellent surgical conditions in case of C-Section. It is the anesthetic technique of choice among obstetric patients. However it is associated with sympathectomy which reduces the venous return and ultimately causes hypotension. This hypotension is mainly due to redistribution of blood volume to the peripheral compartment. Perfusion index which is measured by Pulse Oximetery is a ratio of pulsatile to non-pulsatile blood in the peripheral compartment of the body. As spinal anesthesia causes sympathectomy, peripheral blood volume increases. As a result perfusion index value should rise. This will then co-relate with hypotension. In simple terms those individuals who have a high baseline Perfusion index value will more likely to develop hypotension. This study aims to identify the baseline perfusion index value which co-relates with development of hypotension following sub-arachnoid block for C-section.