carbon monoxide

Question 1

Main causes of exposure

Answer 1

o	Exhaust gases 
o	Fire gas 
o	Burning in high temperature (fires) 
o	Mobile electricity generator 
o	Smoke of cigarettes and pipes 
o	Boiler room 
o	Impaired ventilation

Question 2

Lethal dose

Answer 2

1000ppm (0.1% of carbon monoxide in the air) –

10 mins in a closed garage or 1 hr in a larger room

Question 3

characteristic of CO

Answer 3

heavy gas – accumulates near the floor

Animals exhibit faster intoxication symptoms

Question 4

MOA of CO

Answer 4

1. CO binds with Hb and creates carboxyHb
   - Prevent Hb from binding to oxygen as the affinity to Hb is higher for CO – 250 times higher
   - Only very high concentration of O2 can displace CO molecule – can be use as therapy for CO intoxication
2. availability of O2 for tissues (brain, heart)
   - CarboxyHb creation
   - Progressive reduction of arterial blood saturation with O2
   - Increased vol of arterial blood for CO2
   - Delayed time of “overcome” – due to pCO2 does not rise  no stimulation of respiration (our body unable to detect CO asap and tot that CO is O2)
3. CO binds with cytochrome oxidase
   - Interferes with cellular metabolism
4. ROS release – oxidative damage to cells and tissues

Question 5

% of CarboxyHb vs toxic effects

Answer 5

10-20: Significant weakness, disequilibrium, excessive fetus hypoxia (miscarriage in early pregnancy stage)

30-60: Tachycardia, tachypnoea, EEG, ECG disturbances, coma

> 60: Sudden death without any preliminary

Question 6

What parameters are not correspond to clinical signs of CO

Answer 6

Blood parameters measured after implementation of O2 therapy probably do not correspond to clinical symptoms

Question 7

CO vs general aneasthesia

Answer 7

o CO is created due to reaction of volatile anaesthesia with dry lime

• Esp. barium hydroxy lime
• The change of colour of the adsorbent mean we need to change it

Question 8

factors that contribute to CO release during anaesthesia:

Answer 8

1. anaesthetic drugs Desflurane> enflurane > isoflurane > sevoflurane > halothane
2. adsorbent humidity
   drier the lime, less CO is created
3. types of adsorbent
   - Barium hydroxyl lime – creates more CO than soda lime
   - Higher temperature of adsorbent  more CO is being created
   - Higher conc of anaesthetic  more CO is being created

Question 9

Diagnosis of CO

Answer 9

• Sudden death – no prodromal signs
• History – impaired ventilation, heating system
• Lab diagnosis – cherry red color blood
• Miscarriages in asymptomatic cattle
• No anomalies, no infections in the cow
• But cherry red colour of the foetus skin

Question 10

therapy of CO intoxication

Answer 10

o 100% oxygen through a mask or endotracheal tube

Half life of CO

• 240 min at normal atmosphere
• 60 min – in presence of 100% oxygen
• 23 min – in hyperbaric chamber

Fluid therapy ?? why

The first results 1-4 hrs after the onset of therapy