Accelerated Clearance of CO by ClearMate™
WENQING WU, YUNYU MA, FANG JIANG. A Clinical Study of Treatment for Delayed Neuropsychoneural Sequelae Caused by Acute CO Poisoning with ClearMate™ Gas Poisoning First Aid Ventilator. [Translated from original text]: Chinese Journal of Clinicians (Electronic Edition). Vol 12.24, No. 12, 2015
In this, the only clinical study of the effectiveness of the ClearMate™, the first 320 of 639 consecutive patients with CO poisoning received standard treatment (including 100% O2 plus hyperbaric O2) and the next 319 patients received standard treatment plus ClearMate™. The combined percentages of ‘cures’ [conscious, no sign of CO poisoning, normal ECG, Barthel Index> 40] and ‘effective’ [conscious, continent, no sign of CO poisoning, minor abnormalities in ECG, Barthel index < 40] in the control and ClearMate™ groups were 78 and 99%, respectively. Adverse neurological sequelae (unstated time after exposure) were observed in 71 (22.2%) of control patients but only 3 (0.09%) of the ClearMate™ group.
FISHER, J.A., SOMMER, L.Z., RUCKER, J., VESELY, A., LAVINE, A., GREENWALD, Y., VOLGYESI, G., FEDORKO, L., & ISCOE, S. Isocapnic hyperpnea accelerates carbon monoxide elimination. Am J Respir Crit Care Med 159, 1289-1292, 1999
In anesthetized ventilated dogs exposed to CO, the mean half-times of elimination of CO when ventilated with room air were 212 min, 42 min on 100% O2 at six-times control ventilation (i.e., hypocapnia), but only 18 min when ventilated with O2 at six times control with O2 but normocapnia maintained, a half-time similar to that in two dogs treated with hyperbaric O2.
TAKEUCHI, A., VESELY, A., RUCKER, J., SOMMER, L.Z., TESLER, J., LAVINE, E., SLUTSKY, A.S., MALECK, W.H., VOLGYESI, G., FEDORKO, L., ISCOE, S., & FISHER, J.A. A simple “new” method to accelerate clearance of carbon monoxide. Am J Respir Crit Care Med 161, 1816-1819, 2000.
Seven healthy male volunteers with carboxyhemoglobin (COHb) levels of 10-12% breathed either 100% O2 at resting ventilatory levels (4.3 to 9.0 L/min) for 60 min or O2 containing 4.5 to 4.8% CO2 (to maintain normocapnia; i.e., isocapnic hyperpnea, IH) at 2 – 6 times resting ventilation for 90 min. The mean half-time of the decrease in COHb fell from 78 min during resting ventilation with 100% O2 to 31 min during IH with O2. Even modest increases in ventilation caused large falls in half-time of CO elimination.
RUCKER, J., TESLER, J., FEDORKO, L., TAKEUCHI, A., MASCIA, L., VESELY, A., KOBROSSI, S., SLUTSKY, A.S., VOLGYESI, G., ISCOE, S., & FISHER, J.A. Normocapnia improves cerebral oxygen delivery during conventional oxygen therapy in carbon monoxide-exposed research subjects. Ann Emerg Med 40, 611-618, 2002.
In a randomized, single-blinded, crossover design, 14 human subjects breathed gas containing CO on two different days until their COHb levels reached 10-12%. Each subject then breathed hyperoxia with (one day) or without (the other day) normocapnia. Relative changes in cerebral O2 delivery (DO2) were calculated as the product of blood O2 content and middle cerebral artery velocity (an index of cerebral blood flow) as measured by transcranial Doppler ultrasonography. Maintaining normocapnia during hyperoxic treatment resulted in significantly higher DO2 compared with standard O2 treatment. Normocapnia prevented cerebral vasoconstriction and therefor accelerated elimination of CO due to increased minute ventilation.
FISHER, J.A., ISCOE, S., FEDORKO, L., & DUFFIN, J. Rapid elimination of CO through the lungs: coming full circle 100 years on. Exp Physiol. 98: 1282-1289, 2011.
A history of the treatment of CO poisoning, relating how an effective treatment (carbogen) used almost a century ago was replaced by hyperbaric O2 even though the efficacy of the latter is ineffective, mostly due to delays in initiating treatment if when available. Isocapnic hyperpnea instituted with ClearMate™ can be initiated at the site of poisoning and could be made available in developing countries with a high prevalence of CO poisoning but limited resources.
ZAVORSKY, G.S., TESLER, J., RUCKER, J., FEDORKO, L., DUFFIN, J., & FISHER, J.A. Rates of carbon monoxide elimination in males and females. Physiol Rep. 2(12): e12237, 2014.
To verify and explain the previously reported shorter half‐time of elimination (t½) of CO in females compared to males, 17 healthy subjects (9 men) were exposed to CO on 3 different days to raise COHb levels to ~10%. They then, in random order on the 3 days, breathed 100% O2 (no CO2 added), breathed O2 with normocapnia maintained, or breathed at~4x resting minute ventilation. Minute ventilation, hemoglobin concentration [Hb] and COHb were measured at 5 min intervals, and the t½ of reduction of COHb calculated. Total hemoglobin mass (HbTOT) was calculated from [Hb] and estimated blood volume from a nomogram based on gender, height, and weight. The t½ in females was consistently less than in males even after controlling for differences in alveolar ventilation, the largest differences in t½ occurring at low alveolar ventilations. Normalizing for HbTOT, however, eliminated differences in t½ at alveolar ventilations between 4 and 40 L/min. Thus, differences in alveolar ventilation and HbTOT explain why t½ of CO elimination differ between men and women.
RUCKER, J. & FISHER, J.A. Carbon Monoxide Poisoning. In Clinical Critical Care Medicine. Eds. Albert, R.K., Slutsky, A.S., Ranieri, M., Takala, J., & Torres, A. Clinical Critical Care Medicine. Ch 63, 679 – 683, 2006.