Haemodynamic changes during spinal anaesthesia for elective caesarean
Research type
Research Study
Full title
Haemodynamic changes during spinal anaesthesia for elective Caesarean section; an observational study using non-invasive cardiac output (Pulse Wave Transit Time) monitoring.
IRAS ID
145831
Contact name
Packianathaswamy Balaji
Contact email
Sponsor organisation
Hull and East Yorkshire Hospitals NHS Trust
Research summary
Anaesthesia for pregnant women could be challenging on many occasions as pregnancy causes a variety of physiological changes in the body. In pregnancy, cardiac output (CO) increases by 40% from 3L/min (pre-pregnancy level) to 4.5L/min (third trimester of pregnancy). This is through an increase in heart rate (by 20%) and stroke volume (by 30%). Aortocaval compression plays a vital role in maintaining blood supply to fetus and contributes to hypotension when they lie supine which usually happens after 20 weeks of pregnancy. This has generated a lot of research into maternal haemodynamics.
Incidence of hypotension is around 80% in pregnant patients undergoing caesarean section under spinal anaesthesia 1. There are many contributing factors for this hypotension. The primary cause is due to decrease in CO as a result of decreased preload and/or a decrease in systemic vascular resistance (SVR) from a spinal-induced sympathetic blockade. Several strategies for the prevention and treatment of hypotension have been suggested, such as fluid loading and the administration of vasoconstrictors. Current evidence supports the maintenance of maternal systolic blood pressure at baseline throughout the procedure, and also suggests that phenylephrine is the vasoconstrictor of choice for the management of spinal-induced hypotension during Caesarean section 2. There are possibilities of changes in CO and SVR following intrathecal injection, after delivery of the baby and in the postoperative period. It would be ideal to have the benefit of a complete haemodynamic profile of each individual patient throughout the procedure. A few years ago we could only monitor CO and obtain complete haemodynamic profile using an invasive pulmonary artery catheter. With recent advances, there are few monitors available in the market which could measure CO without inserting invasive lines like arterial cannula or pulmonary artery catheters. These monitors have been used in awake patients with comfort and would be beneficial for obstetric patients in obtaining a complete haemodynamic profile during caesarean section.
Estimated Continuous Cardiac Output (esCCO) is a new technology to determine the cardiac output using Pulse Wave Transit Time (PWTT) which is obtained by the pulse oximetry (SpO2) and electrocardiogram (ECG) signals from each cycle of the ECG and peripheral pulse wave. esCCO provides real time, continuous and non-invasive cardiac output measurement alongside the familiar vital sign parameters of ECG and SpO2. This monitor will give us continuous ECG, heart rate (HR), blood pressure (BP) and SpO2 monitoring. So far, there are no research conducted using this principle in obstetric patients. So we would like to evaluate the usage of this monitoring in our obstetric population.
REC name
Yorkshire & The Humber - Sheffield Research Ethics Committee
REC reference
14/YH/0050
Date of REC Opinion
10 Apr 2014
REC opinion
Further Information Favourable Opinion