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Types of Carbon dioxide absorbent used in anesthesia machines like Soda lime

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 Function of  carbon dioxide absorbent  ( sodalime ) : 

makes re-breathing possible , therefore it also  conserve  gases and volatile agents also decreases operation room pollution and avoid hazard of co2 rebreathing .



ot technician yashasvi
drager anesthesia machine 


Types of Carbondioxide absorbents used in anesthesia machine :

Most commonly used Carbondioxide absorbent is soda lime .

1. Sodalime : 

  • 1. It consists of 
  • Ca (OH)2 : 94%
  • NaOH      : 5 %  ( it acts as a catalyst )
  • KOH : 1 %
  • COLOR INDICATOR 
  • Silica  ( to prevent dust formation )

 COLOR INDICATORS used in sodalime are :

  1. Durasorb : which is pink when fresh and becomes white when exhausted
    2. sodalime
    durasorb indicator in sodalime 
      
  2. Ethyl violet : which is white when fresh and becomes purple on exhaustion    




  3. Clayton : red when fresh and becomes yellow on exhausted .
  4. Phenolphthalein : which is white when fresh and becomes pink on exhaustion .  

NOTE : color of indicator is changed due to change in th pH of granules .


PROPERTIES of sodalime :
  • hardness of granules should be more than 75, otherwise it will form dust and that can be inhaled by the patient . 
  • 14 % to 19 %    of moisture is needed  for proper absorption  
  •  4 to 8 mesh is the size of sodalime granules ( mesh is the unit used in america )
  •  there should be more than 50 % of air space in sodalime canister as reaction takes place on the surface of  granule . 
  •  100 g of sodalime can absorb 24 to 26 L of co2 .

 PROBLEMS / DISADVANTAGE OF USING SODALIME 

  • Sevoflurane is unstable in sodalime  and   produce  compund A  which is nephrotoxic . ( harmful to kidney )

so we should always keep the fresh gas flow more than 2 L while using sevo .

  • dry Sodalime can produce carbon monoxide when it reacts with desflurane > enflurane >isoflurane>halothane=sevoflurane .
  • dry sodalime can also cause burn of respiratory mucosa with sevoflurane by producing hydrogen fluride .

as sodalime has these disadvantages scientist came with alternatives 

  1. litholyme lithium containing or lithium based absorbent like spiralith 
  2. absorbent which lack activators  ( as compound A and CO is produced due to activators )

2. Lithium Hydroxide lime : 

litholyme contains 
LiCl as catalyst to accelerate the formation of CaCO3 
ethyl violet as indicator
( does not contain NaOH or KOH  )

co2 absorbing capcity is equal to sodasorb and more then amsorb . 

FEATURES : 

  • does not produce compound A even if it is dry 
  • does not produce CO
  • GENERATES LESS HEAT
  • COMPARABLE PRICE TO SODALIME 

3. Spiralith :

has lithium hydroxide as it main constituent  (not calcium hydroxide like others )

FEATURES :

  • does not degrade volatile agents 
  • does not dry ( as water molecule is bonded chemically)
  • it is recyclable 
  • does not produce dust

DISADVANTAGE :

DON'T HAVE INDICATORE SO FI02 MONITORING IS REQUIRED . 

INTERESTING FACT ABOUT LITHOLYME AND SPIRALITH  

THEY WERE USED IN SPACE AND SUBMARINES FROM LONG TIME YET NEW IN ANESTHESIA  APPLICATIONS 

4. BARYLIME :

It consists of 80%  Ca(OH)  and 20 % Ba(OH)

HAS BEEN WITHDRAWN FROM MARKET IN 2005 DUE TO LIFE THREATENING FIRE AND EXPLOSION IN BREATHING CIRCUITS WITH SEVOFLURANE .

5. AMSORB : 

also known as calcium hydroxide lime 

contains  CaOH and CaCl 

FEATURES : 

DOES NOT PRODUCE COMPOUND  A  NOR CO 

DISADVANTAGE  :

HIGH COST 
LESS ABSORPTION 

6. NEW " HOUSE BRAND " ABSORBENTS :

made by Drager and GE like companies .

exmaple

Dragersorb 800 PLUS

 made by drager company for their machines 
it has decreased amount of NaOH and no KOH . 
it dont produce compund A 

Medisorb™ CO2 Absorbent

also has decreased amount of strong bases 
used in aisys and avance anesthesia machines . 



 click here to see composition of all co2 absorbents . 




ot technologist yashasvi verma
yashasvi verma ot technologist

Clinical Signs of Exhaustion of Co2 Absorbent :

  1. 2-3cm H20 of inspired CO2
  2. Rise (later a fall ) in heart rate and BP .
  3. Hypercapnia 
  4. respiratory acidosis 
  5. dysrhythmia 
  6. increased bleeding at surgical site 
  7. increased end tidal CO2 .
  8. not dark or cherry red blood 
  9. SIGN OF SNS ACTIVATION                
  • SWEATING
  • CARDIAC IRREGULARITIES 



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