Preventing hypovolemia during major surgery

All patients undergoing major surgery are at risk from complications caused by a reduction in circulating blood volume. Hypovolemia can occur during longer surgical procedures as a result of the combined effects of pre-operative fasting, the anaesthetic agent and the blood lost during surgery. The reduced circulating blood volume is unable to carry sufficient oxygen to the major organs and tissues, which can lead to serious post-operative complications, delayed recovery time and a longer hospital stay for the patient. Key to improving the outcome of patients having major surgery is optimal management of cardiac output, fluid balance and haemodynamic status by the anaesthetist during surgery. Traditionally, cardiac output has been monitored using a variety of techniques including the invasive technique of inserting a pulmonary artery catheter or using systems based on pulse contour analysis and dye dilution. However, a minimally-invasive evidence-based solution for monitoring cardiac output and intravascular fluid status during surgery is offered by Oesophageal Doppler Monitoring (ODM), developed by Deltex Medical. Ewan Phillips, Deltex Medical chief executive, explained that, although the CardioQ-ODM device has been available for around 15 years, the NHS is not yet making the most of the technology. It is used in around 250 NHS hospitals across the UK, but Mr Phillips believes that the NHS could go much further to prevent hypovolemia during surgery. He said: “The technology is only being deployed in around 15% to 20% of surgical procedures that are now covered by the NICE guidance, so there is still some way to go in the education process for ODM. We hope that the NICE guidance will now encourage greater use of ODM in the operating environment, helping to greatly improve patient outcomes.”

NICE approval

ODM has recently received approval from National Institute for Health and Clinical Excellence (NICE) following the publication of final guidance recommending its use.1 The NICE guidance states that the CardioQ-ODM should be considered for use in patients undergoing major or high-risk surgery or other surgical patients in whom a clinician would consider using invasive cardiovascular monitoring. This includes patients undergoing major or high-risk surgery or high-risk patients undergoing intermediate-risk surgery. NICE acknowledges that there is a strong case for the use of the technique in the NHS, stating that there is evidence to support the claims for a reduction in postoperative complications, use of central venous catheters and in-hospital stay, with no increase in readmission rates or repeat surgery, when compared with conventional clinical assessment with or without the use of a more invasive cardiovascular monitoring technique. It was also noted that, although the evidence relating to the benefits of using the system were particularly convincing for patients undergoing gastrointestinal surgery, benefits were also observed in patients undergoing other types of surgery too. However, the technique cannot usually be used in patients undergoing head and neck, oesophageal or aortic surgery and it is poorly tolerated by conscious patients after surgery.