Method, Device, & Software for Delivery of Anesthetic Vapor
OHSU # 1798
An anesthetic delivery system which digitally controls agent temperature to deliver clinical anesthetic vapor concentrations.
Problem: Currently available variable-bypass anesthetic vaporizers are single-agent specific, require frequent calibration and maintenance, and are heavy and slow to change concentration. This can be challenging in non-operating room circumstances such as animal research laboratories, intensive care units, medical transport, and military field environments.
In contrast, our vaporizer can contain and vaporize any agent by direct digital temperature control of the anesthetic. The device comprises an insulated vessel for the liquid anesthetic, a thermoelectric refrigeration system to cool the vessel, and an electronic controlling device with custom software to set the desired agent concentration and temperature using proportional-integral-derivative algorithms. Advantages of the OHSU device include:
· eliminates the need for expensive servicing and calibration;
· decreased size and weight makes it ideal in space constrained environments;
· use is not tied to any one anesthetic: can be used as a universal system for a wide variety of liquid anesthetics, and;
· use of the device is ideal for suboptimal situations such as rural clinics, confined spaces, field military use, or veterinary use.
The OHSU device works by cooling an anesthetic gas to very low temperatures at which clinical concentrations of vapor are created. The concentration of anesthetic delivered to the patient is controlled by controlling the temperature of the anesthetic liquid rather than flow of the fresh gas as in variable-bypass vaporizers.
Currently, the temperature-vapor pressure relationship of anesthetics (desflurane, isoflurane, sevoflurane) is known for temperatures above 0° degrees Celsius. Because the production of vapor leads to a decrease in temperature, which in turn leads to a decrease in saturated vapor pressure, existing variable-bypass vaporizers are temperature-compensated and contain significant thermal mass to prevent inconsistency in the rate of vapor production caused by changes in fresh gas, ambient and vaporizer temperatures.
The OHSU device achieves clinically relevant concentrations of anesthetic vapors at temperatures of less than 0° C employing data originated at OHSU which characterizes the behavior of anesthetic liquids at very low temperatures. This data associates temperature with concentration at clinical concentrations. In the OHSU device, these low temperatures are applied to the liquid anesthetic such that the vapor is at clinical concentration and can be delivered to the patient.
In the North American total anesthesia and respiratory devices market for 2012, anesthesia machines represented 6.2% of the total market. This translates to a $5.703M market with a CAGR (compound annual growth rate of 4.9%. Segmenting out the United States for 2013, all anesthesia machines had a value of $357M with a volume of 6,561 units and a CAGR of 9.5%. The distribution share in 2013 was $286.6M to US hospitals and $51.1M to US laboratories.
A prototype has been developed. The temperature-vapor pressure relationship at clinical concentrations for desflurane, isoflurane, and sevoflurane at temperatures below zero degrees Celsius was tested and results established the “TMAC” (temperature minimum alveolar concentration) for the anesthetics.
US Provisional patent application filed July 29, 2013, s/n 61/859,462.
Patent rights are available for exclusive in-licensing
- Michael Hutchens, SM.Anesthesiology & Perioperative Medicine
- Nabil Alkayed, SM.Anesthesiology & Perioperative Medicine
- Henry Casson, SM.Anesthesiology & Preoperative Medicine
- Katie Schenning, SM.Anesthesiology & Preoperative Medicine
For more information, contact:
Senior Technology Development Manager