Monitoring for Carboxyhemoglobinemia During Fire Rehab with the Nonin CO-MetTM Noninvasive Oximetry System is more reliable and faster than the Rad-57
Background
Carbon monoxide (CO) poisoning is a leading cause of unintentional poisoning deaths and claims 500 victims annually in the United States. Recent studies suggest that CO poisoning is responsible for at least 50,000 emergency department admissions annually. CO poisoning is traditionally diagnosed with hemoximetry from arterial blood draws. However, advances in pulse oximetry have enabled noninvasive monitoring of carboxyhemoglobin (COHb). An important use of this technology has been firefighter rehabilitation. The National Fire Protection Association suggests assessment of firefighters for CO poisoning after exposure. Exposure can result from settings such as operating near fire locations without respiratory equipment. As such, many emergency medical services (EMS) have adopted the Rad-57 pulse oximetry system for monitoring COHb as a part of their standard fire rehabilitation. Still, multiple studies have indicated varying reliability and accuracy of the Rad-57 device for CO monitoring. Nonin Medical has recently developed a new oximetry system capable of measuring dyshemoglobins with a clinical accuracy during hypoxia. The purpose of this study was to evaluate the reliability of the COHb measurements from the Nonin device versus the Rad-57 device, currently used during fire rehabilitation.
Methods:
The study was Institutional Review Board-approved and conducted in compliance with the Declaration of Helsinki. All subjects provided written informed consent. The ongoing study is a prospective observation study completed by Health East EMS personnel.
Fire fighters undergoing standard fire rehabilitation were enrolled and had a DCI sensor (no light shield) with a Rad-57 Pulse CO-OximeterTM utilized in keeping with standard use of the product by our team. On the opposite hand, a Nonin 8330AA CO-MetTM fingertip sensor was applied to the index, middle, or ring finger. Patient demographics were collected along with the noninvasive COHb, peripheral oxygen saturation, and pulse rate values from the oximeters. Observations from the EMS personnel operating the two systems were also collected.
Results and Discussion:
Preliminary results include 59 measurements on 43 (42 M: 1F, Age: 36 ± 10 years old, one smoker) enrolled firefighter patients. Longer fire events occasionally resulted in multiple rehabilitations and measurements for a single firefighter. To date, the Nonin CO-MetTM System reported readings for COHb on 100% of attempted measurements, whereas the Rad-57 had a blanked display on 25% of attempted measurements. Additionally, EMS operators noted that the Nonin device displayed readings faster than the Rad-57. 60% of blank readings on the Rad-57 occurred at a nighttime fire with an ambient temp of 18°F. The Rad-57 manual notes that ambient light can interfere with its COHb readings. Light shields were not used with the Rad-57 device as the Rad-57 recordings were not taken in direct sunlight or in proximity to strobing light. Per the manufacturer, the Nonin device require no light shield.
Conclusion:
These preliminary results suggest the new Nonin CO-MetTM Noninvasive Oximetry System delivers reliability in a fire rehabilitation environment. The ongoing study will continue to expand on these results adding subjects and observers. Further work is still needed to verify the accuracy of the new Nonin device in clinical use.
