Development Of Novel Methods For Non-invasive Measurement Of Cardiac Output And Lung Volume During Anaesthesia
Funder
National Health and Medical Research Council
Funding Amount
$257,970.00
Summary
In Australia approximately 2 million anaesthetic procedures are performed annually. Approximately one patient in 20,000 dies during or shortly after an anaesthetic from complications related to the anaesthetic itself, and as many as one in 170 suffers severe complications. Mortality and severe morbidity are often ultimately associated with lack of oxygen in the tissues. Oxygen is transported from the lungs to the tissues by the blood. The oxygen content of arterial blood is monitored by pulse ox ....In Australia approximately 2 million anaesthetic procedures are performed annually. Approximately one patient in 20,000 dies during or shortly after an anaesthetic from complications related to the anaesthetic itself, and as many as one in 170 suffers severe complications. Mortality and severe morbidity are often ultimately associated with lack of oxygen in the tissues. Oxygen is transported from the lungs to the tissues by the blood. The oxygen content of arterial blood is monitored by pulse oximetry during every anaesthetic, but blood flow is not. Cardiac output is measured in only a very small proportion of anaesthetised patients using intravenous catheters that pass through the heart to the lungs. This procedure is invasive and is associated with significant morbidity and mortality. At present there is no easy way to monitor cardiac output non-invasively during anaesthesia. Our proposed research project, currently underway in conjunction with an industrial partner, is aimed at the development of a reliable, rapidly repeating, non-invasive method for monitoring total cardiac output and lung volume in every patient who has an anaesthetic. The purpose of the new monitor is to ensure that potential problems with oxygen supply to the tissues are detected and corrected promptly. Our new monitoring technique is computer-controlled, can function without intervention by the anaesthetist and has very few side-effects. It can be added to any anaesthetic machine. Such a measurement technique is likely to have an impact on anaesthesia similar to that of pulse oximetry in the 1980's, and, if suitably adapted, is likely to find applications in other fields, such as intensive care, sports medicine, the respiratory function laboratory and in veterinary medicine.Read moreRead less
Commercial Testing Of A Physiologically Based Theory Of Oscillatory Brain Electrical Activity In Anaesthesia Monitoring
Funder
National Health and Medical Research Council
Funding Amount
$191,165.00
Summary
While the mechanisms of local anaesthesia are comparatively well known, the mechanisms whereby anaesthetics impair consciousness remain unresolved. This lack of understanding has implications in our ability to monitor the level of anaesthesia while anaesthetic consumption and side effects are minimized. Despite this a number of devices have been developed that attempt to monitor the depth of anaesthesia by quantifying the brains electrical activity. All monitors analyse the activity using a set ....While the mechanisms of local anaesthesia are comparatively well known, the mechanisms whereby anaesthetics impair consciousness remain unresolved. This lack of understanding has implications in our ability to monitor the level of anaesthesia while anaesthetic consumption and side effects are minimized. Despite this a number of devices have been developed that attempt to monitor the depth of anaesthesia by quantifying the brains electrical activity. All monitors analyse the activity using a set of criteria that have been developed by trial and error. The research of Dr David Liley and his team, at Swinburne University of Technology, has resulted in a detailed understanding of the physiological mechanisms that generate brain electrical activity. The outcome is a practical means to carry out a System Based Analysis of Brain Electrical Response (SABER). In 2004, Dr Liley began working with Cortical Dynamics, a company involved in the commercialisation of medical devices. This collaboration incorporated the SABER system into a new prototype device called the Brain Anaesthesia Response (BAR) monitor. In 2004 Dr Liley and Associate Professor Kate Leslie collaborated in a trial, at the Royal Melbourne Hospital to test the sensitivity of the SABER system in quantifying the effect that various levels of nitrous oxide have on measures of anaesthetic depth. The Australian and New Zealand College of Anaesthetists supported this study. Initial results obtained with sevoflurane and 3 levels of nitrous oxide showed the ability to differentiate between conscious and unconscious states of patients based on two physiological characterizations of higher brain dynamic state. The next step requires commercial product validation (ie scale up) and further clinical efficacy in testing beta stage depth of anaesthesia BAR units. Completion of this will help the technology move away from a low volume prototype system into a commercially applicable device.Read moreRead less
We will conduct a clinical trial of the effectiveness of a continuous auditory display of an anesthetized patient's respiratory status. Expired carbon dioxide monitoring has helped reduce respiratory incidents since its widespread introduction in the late 1980s, but a continuous auditory display of respiratory status may reduce incidents further. We will conduct a clinical trial with 10 anaesthetists of continuous auditory respiratory monitoring. Successful outcome may lead to commercial uptake.
Development And Clinical Evaluation Of A Depth Of Anaesthesia Monitor
Funder
National Health and Medical Research Council
Funding Amount
$424,785.00
Summary
Waking up during surgery (awareness under anaesthesia) is a frightening reality for some patients. Although uncommon (occurring in about 1 in 1000 operations), it remains one of the main concerns of patients before their surgery. Recent studies (including our own) have demonstrated that processed EEG monitoring using bispectral index (BIS) can markedly reduce the risk of awareness. Other EEG monitors are being developed, but each have weaknesses. As approximately two million Australians have a g ....Waking up during surgery (awareness under anaesthesia) is a frightening reality for some patients. Although uncommon (occurring in about 1 in 1000 operations), it remains one of the main concerns of patients before their surgery. Recent studies (including our own) have demonstrated that processed EEG monitoring using bispectral index (BIS) can markedly reduce the risk of awareness. Other EEG monitors are being developed, but each have weaknesses. As approximately two million Australians have a general anaesthetic each year, about 2000 will suffer an episode of awareness. More than 60 million people around the world have an anaesthetic, and so the problem is substantial. This suggests the potential benefits (health outcomes, commercial gains) are very great. In 2000 less than 5% of US hospitals used BIS monitoring; the current figure in the US is about 69% of the best-rated hospitals (US News and World Report) and 78% of teaching hospitals. A similar rapid growth is occurring in Australia and Europe. We are working with a successful Australian Company (Compumedics Ltd) to develop a better awareness monitor. We plan studies in groups of patients have surgery.Read moreRead less