nitrous oxide article

Question 1

2nd gas effect

Answer 1

1. Because high fraction of N2O and n2o is more soluble N2, it diffuses rapidly across alveolar basement membranes. the RAPID EXIT of N2o from alveoli causes remaining gas concentrated. Accelerate uptake , speeding onset of anesthesia. 2. Exit of No2 causes FRESH GAS TO BE DRAWN in to gas exchanging regions of the lung. Both 1&2 contributes to accelerated uptake of companion gas.

Question 2

diffusion hypoxia

Answer 2

n2o enters alveoli from blood faster than nitrogen, diluting O2 concentration in the lung.

Question 3

how is n2o eliminated?

Answer 3

unchanged, entirely via the lungs, very small thru skin.

Question 4

n2o receptors

Answer 4

inhibits NMDA, stimulates opioid, alpha 1 and 2 adrenergic and dipominergic.

Question 5

resp impact

Answer 5

decrease TV, increase RR, minute ventilation unchanged.

Question 6

cardiovascular impact

Answer 6

direct myocardial depression, but increases sympathetic outflow. thus HR up. vascular resistance increased. avoid in pt with pulmonary HTN.

Question 7

CNS impact

Answer 7

increased metabolism rate, increased cerebral blood flow (caused by metabolism rate, not dilation), increased intracranial pressure, decreased cerebral perfusion pressure.

Question 8

neuromuscular impact

Answer 8

it increases skeletal muscular activity, less depressant effect at the neuromuscular junction than other inhalation agents. Does to potentiate non-depolarizing NMBA.

Question 9

analgesic effect

Answer 9

it has analgesic actions by activation of opioids receptor in midbrain.

Question 10

N2O MAC

Answer 10

105%

Question 11

why combine n2o with other agents

Answer 11

decreases required dose of other agents’ cardiovascular depression effect, cheap, 2nd gas.

Question 12

adverse effects of n2o

Answer 12

PONV; air-filled spaces; inactivation of B12 (cobalamin), cofactor for enzyme methionine synthase, leading to immune suppression and teratogenic problem; hypoxic mixture; occupational exposure; recreational use; teratogenicity(caused by alpha 1 adrenergic stimulation); environment concern (x200-300 trapping heat);

Question 13

situations n2o have serious deleterious consequences

Answer 13

pneumothorax, intestinal obstruction, intraocular gas, middle ear surgery, air embolism, decompression sickness (bubbles formed d/t pressure change)

Question 14

what is an advantage of n2o comer\pared with IV drug?

Answer 14

exhaled concentration may be measured, providing indication on in vivo partial pressures.

Question 15

Describe megaloblastic changes

Answer 15

the immune suppression effect is associated with marrow suppression, i.e. precipitate megaloblastic changes in bone marrow.