Nitrous oxide Flashcards
(23 cards)
When was nitrous oxide first used?
1844
Properties of nitrous oxide
Colourless
odorless
non irritating
nonflammable
What is the most toxic contaminant of nitrous oxide
nitric oxide
what is the major contaminant of nitrous oxide
nitrogen
how is nitric oxide toxic
- highly reactive
- oxidises pulmonary mucosa leading to pulmonary edema
- oxidises hb so it cannot carry o2
What is the blood:gas partition coeff of nitrous oxide?
0.47
does nitrous oxide bind with hb?
no
does nitrous oxide transform within the body?
no
what patients should avoid nitrous oxide and why?
bowel obstruction, otitis media, recent eye surgery using perfluoropropane and pneumothorax because of possibility of high gas volume and pressure
What is the MAC deliverable by a dental unit?
0.5 because of leakage, dead space and mouth breathing
actions of nitrous oxide
- mild analgesia
- depressed response to hypercapnia and hypoxemia
What happens if nitrous oxide is given with sedatives and opioids?
- changes cardiovascular function if used with sedatives and opioids
What is the concentration of n2o of patient can feel tingling of hands and feet?
10-20%
what is the % of n2o if patient can feel circumoral numbness?
20-30%
Droning sounds are an indication of what % of n2o?
20-40%
When does numbness of tongue begin to set in with n2o?
20-40%
Dysphoria and increased sleepiness at what stage?
30-50%
Do you give n2o to a person with a URTI or sinus blockage?
absolutely not
what can prolonged exposure to n2o cause?
myeloneuropathy
N2o in child with MTHF reductase deficiency - is it safe?
no - can lead to death
Major action of n2o
Oxidises cobalt atom in reduced vitamin b12
which enzymes is vitamin b12 essential for?
methionine synthase
methylmalonyl coa mutase
leucine 2,3- aminomutase
What reactions are facilitated by the increase in methionine due to n2o?
- protein synthesis
- Methylation of DNA, RNA, proteins, membrane phospholipids
- Antioxidant activity
