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Correspondence  |   December 1997
Optimal Rehydration of Desiccated CO2Absorbents 
Author Notes
  • Associate Professor of Anesthesiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226.
Article Information
Correspondence
Correspondence   |   December 1997
Optimal Rehydration of Desiccated CO2Absorbents 
Anesthesiology 12 1997, Vol.87, 1590. doi:
Anesthesiology 12 1997, Vol.87, 1590. doi:
To the Editor:-The work by Baxter and Kharasch [1 ] confirms the concept that the CO2absorbent water content is critically important to the production of CO from anesthetic breakdown. Adding water to desiccated absorbent provides a safe, easy, cost-effective maneuver that can reduce the risk of CO poisoning from anesthetic breakdown. If this technique is brought into clinical practice, two additional factors may need to be considered. First, because the water content of absorbent in clinical use is rarely known, it may be a fairly common occurrence to add water to absorbent that is already hydrated. Although a small decrease in CO2absorption rate results from increasing the absorbent water content above 22%, [2 ] this will probably be of minimal clinical significance because the actual capacity to absorb CO2is not greatly altered by water content. However, it may be more important to ensure that the water is well distributed throughout previously desiccated absorbent to ensure that all areas of absorbent have been rehydrated and are therefore incapable of producing CO. Baxter and Kharasch [1 ] showed that some CO production still resulted, even though the absorbent had been rehydrated with the full complement (13%) of water. This may be a result of incomplete mixing of the water with the absorbent granules, leaving some absorbent sufficiently dried to allow chemical reaction. When rehydrating potentially dried absorbent in a clinical situation, particularly when the absorbent is packaged in plastic canisters that may impair water distribution (as compared with loose fill absorbent), it may be desirable to use even greater quantities of water than the minimum to ensure that all absorbent has been rehydrated. If sufficient care can be taken to avoid skin injury from dissolved alkali, in some situations, it may even be reasonable to briefly plunge the entire CO2absorbent canister into a bucket of water to ensure that the absorbent is completely rehydrated.
Harvey Woehlck, M.D.
Associate Professor of Anesthesiology; Medical College of Wisconsin; Milwaukee, Wisconsin 53226
(Accepted for publication July 29, 1997.)
References 
References 
Baxter PJ, Kharasch ED: Rehydration of desiccated Baralyme prevents carbon monoxide formation from desflurane in an anesthesia machine. Anesthesiology 1997; 86(5):1061-5.
Brown ES, Bakamjian V, Seniff AM: Performance of absorbents: effect of moisture. Anesthesiology 1959; 20(5):613-7.