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iain-hsm · 18th September 2006, 19:35

Quote: (Originally Posted by Marc T)

Perhaps a chemist egeneer could answer that question? Does the sorb could have any effect on CO accidentaly contained in the loop, because for example of a "bad" compressor?

Thanks Marc

Marc
No the soda lime cannot absorb CO, but what is known however is the ability of strong base limes with some anesthetic gases (using very dry lime) breaking down the anesthetic gas to carbon monoxide.

Carbon monoxide production from desflurane and six types of carbon dioxide absorbents in a patient model
C. Keijzer, R. S.Perez and J. J. de Lange
Background: Desflurane is known to produce high concentrations of carbon monoxide (CO) in desiccated sodalime or Baralyme. Desiccated absorbents without strong bases like potassium hydroxide or sodium hydroxide are reported to produce less or no CO at all. The purpose of this study is to compare the concentration of CO in an anesthesia circuit for desflurane with six different types of completely desiccated CO2 absorbents with less strong bases than sodalime.
Methods: A patient model was simulated using a circle anesthesia system connected to an artificial lung. Completely desiccated CO2 absorbent (950 g) was used in this system. A low flow anesthesia (500 ml min 1) was maintained using desflurane. For immediate quantification of CO production a portable gas chromatograph was used.
Results: Peak concentrations of CO were very high in Medisorb, and Spherasorb (13317 and 9045 p.p.m., respectively). It was lower with Loflosorb and Superia (524 and 31 p.p.m., respectively). Amsorb and lithium hydroxide produced no CO at all.
Conclusion: Medisorb and Spherasorb are capable of producing large concentrations of CO when desiccated. Loflosorb and Superia produce far less CO under the same conditions. Amsorb and lithium hydroxide should be considered safe when desiccated.

Any CO present in "bad air" should be investigated and treated only with a catalytic chemical called Hopkalite and only then if it is found to come from an outside source ie the petrol or diesel engine.

This only works in very dry air ONLY. post filtration after the air is better than minus 50C dewpoint. Only at these dry conditions will it convert the C0 molecule into C02. Even then only with a calculated surface area of chemical against a calculated chemical bed depth with a calculated "dwell time" and a possible increase of the compressors back pressure to around 200 barg from the more common 150barg will this catalytic conversion occur.

IMHO I would not reccomend using air from a compressor that is creating C0 ever this is only due to bad compressor oil, high temp, poor service and is not acceptable. Only air polluted C0 from say petrol or diesel engines should be treated. A compressor creating C0 should be junked. Iain Middlebrook

18th September 2006, 19:35	#3 (permalink)
iain-hsm Custom Title Allowed! Current Rebreather/s: MK 15.X Other CCR Other SCR Other Rebreather/s: Other CCR Other SCR Join Date: Mar 2005 Location: Loughborough England uk Posts: 347	Re: any effect of the sorb on CO? Quote: (Originally Posted by Marc T) Perhaps a chemist egeneer could answer that question? Does the sorb could have any effect on CO accidentaly contained in the loop, because for example of a "bad" compressor? Thanks Marc Marc No the soda lime cannot absorb CO, but what is known however is the ability of strong base limes with some anesthetic gases (using very dry lime) breaking down the anesthetic gas to carbon monoxide. Carbon monoxide production from desflurane and six types of carbon dioxide absorbents in a patient model C. Keijzer, R. S.Perez and J. J. de Lange Background: Desflurane is known to produce high concentrations of carbon monoxide (CO) in desiccated sodalime or Baralyme. Desiccated absorbents without strong bases like potassium hydroxide or sodium hydroxide are reported to produce less or no CO at all. The purpose of this study is to compare the concentration of CO in an anesthesia circuit for desflurane with six different types of completely desiccated CO2 absorbents with less strong bases than sodalime. Methods: A patient model was simulated using a circle anesthesia system connected to an artificial lung. Completely desiccated CO2 absorbent (950 g) was used in this system. A low flow anesthesia (500 ml min 1) was maintained using desflurane. For immediate quantification of CO production a portable gas chromatograph was used. Results: Peak concentrations of CO were very high in Medisorb, and Spherasorb (13317 and 9045 p.p.m., respectively). It was lower with Loflosorb and Superia (524 and 31 p.p.m., respectively). Amsorb and lithium hydroxide produced no CO at all. Conclusion: Medisorb and Spherasorb are capable of producing large concentrations of CO when desiccated. Loflosorb and Superia produce far less CO under the same conditions. Amsorb and lithium hydroxide should be considered safe when desiccated. Any CO present in "bad air" should be investigated and treated only with a catalytic chemical called Hopkalite and only then if it is found to come from an outside source ie the petrol or diesel engine. This only works in very dry air ONLY. post filtration after the air is better than minus 50C dewpoint. Only at these dry conditions will it convert the C0 molecule into C02. Even then only with a calculated surface area of chemical against a calculated chemical bed depth with a calculated "dwell time" and a possible increase of the compressors back pressure to around 200 barg from the more common 150barg will this catalytic conversion occur. IMHO I would not reccomend using air from a compressor that is creating C0 ever this is only due to bad compressor oil, high temp, poor service and is not acceptable. Only air polluted C0 from say petrol or diesel engines should be treated. A compressor creating C0 should be junked. Iain Middlebrook Last edited by iain-hsm : 18th September 2006 at 19:40. Reason: spelling correction
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