About Anesthesia Monitoring

Xhale is developing a breath-based propofol monitor which would offer the ability to monitor propofol concentrations in blood plasma via the exhaled breath. Upon completion of development and testing, the company plans to seek approval of the monitor for deployment in all locations where the drug is used, including sedation suites and intensive care units. The ability to monitor propofol concentrations in blood plasma would give health care professionals real-time feedback for titration of propofol during sedation, which in turn could lead to improved sedation results, including more rapid induction and emergence from conscious sedation, and improved safety and efficiency.

Because propofol is delivered intravenously rather than via the respiratory pathway as a gas, there is currently no method for a health care professional to determine the real-time blood concentration of propofol in a patient in a way that can alter treatment at the point-of-care. Instead, indirect signs of propofol efficacy are measured. Depth of sedation and ventilatory adequacy are monitored by a combination of blood pressure monitoring, heart rate, respiratory rate, oxygen saturation (with a pulse oximeter) and, sometimes, end-tidal carbon dioxide (with a capnometer or capnograph). Xhale’s propofol monitor would be the first system to enable the monitoring of concurrent propofol concentrations in blood plasma using the patient’s exhaled breath for correlation.

Propofol usage has grown rapidly in the past few years and is now one of the most commonly-used intravenous drugs employed to cause conscious sedation. Propofol’s popularity is due to several factors, including several that contribute to improved patient satisfaction. These characteristics include:

• a pleasant mental state
• rapid onset and short duration of action that allows titration of effect with an propofol infusion
• quick recovery from sedation with minimal drowsiness that facilitates early discharge and neurological examination for patients sedated in the ICU
• diminished need for other sedatives (such as opioid narcotics or benzodiazepines) that may result in side effects (such nausea and vomiting)
• reduced recovery times for the patient following the procedure to allow more rapid throughput in a busy sedation suite

For these reasons, propofol is the “go to” drug for many short duration medical procedures (such as colonoscopy) that require conscious sedation.    However, there are potential safety issues surrounding the use of propofol. The drug can be unpredictable in untrained hands, as dosing and titration is variable and is based on the patient’s response and tolerance to the drug, which may vary widely. For example, respiration can change dramatically in a very short time deteriorating to full respiratory arrest, even when propofol is administered in low doses.  

Xhale’s propofol monitor would give health care professionals the real-time feedback they need for titration of propofol during sedation, with improved sedation results and increased safety and efficiency.