Page 1 of 2: a little knowledge is a bad thing..N2o again

doctorgirl78 · Credits: 5316 My Scrapbook

Nitrous Oxide
May lead to megaloblastic changes after 5 hours exposure in critically ill patients…it does cause megaloblastic anemia!!!what is wrong with this choice??
Is not teratogenic when administered to women during the first or second trimesters….accha???I didn’t know that…good
Lowers Pulmonary Artery Pressure….hmmm…..i thought it aint have no effect on resp.CVS
Impairs the " hypoxic ventilatory response…I am lost
Doesnt impair the " hypoxic ventilatory response……….4 or 5 mein sey ek choice correct hai…….itni tubelight to jalti hai…!!

akanksha · Credits: 41227 My Scrapbook My Reading List 14 Books

well,
nitrous oxide does cause megaloblastic anemia!
but it needs minimum of 8hrs exposure!

the interaction of nitrous oxide with the cobalt in Vit B12 is verrrry slow!

it is not teratogenic in humans!(imagine a substance which causes no harm in 1st or 2nd trimester,wat harm can it cause in 3rd trimester).

akanksha · Credits: 41227 My Scrapbook My Reading List 14 Books

the blood/gas partition coefficent of N2O is high!
dat means,nitrous oxide diffuses into alveolar gas faster than nitrogen!(one molecule of nitrogen being replaced by 35 molecules of nitrous oxide).

this causes dilution of alveolar oxygen!which results in hypoxia!

hypoxic ventilatory response is determined mainly by the amount of carbon dioxide!which also gets diluted,due to the above mentioned effect!

so when,ther is hypoxia,ther is hypocapnia toooo! 8)
so the hypoxic ventilatory response is blunted! 8)

Moose · Credits: 1318 My Scrapbook

Harry says >6 hrs of exposure is required for developement of meg. anemia by nitrous

akanksha · Credits: 41227 My Scrapbook My Reading List 14 Books

dont hav any reference,but nitrous oxide,

increases the pulmonary artery pressure!(the same effect,due the high blood/gas coefficient).

n it has a minor depressant effect on heart!most of which is usually compensated!

doctorgirl78 · Credits: 5316 My Scrapbook

thanks akku........see now i can say.nobody explains it better than uuu

and thanks moose too...........everybody seems to be so chivalrious now.......thanks a lot.

neodoc · Credits: 2306 My Scrapbook

NITROUS OXIDE
Indications¾ Anesthetic potency relatively weak; usually must be supplemented with other agents.

Often given concurrently with one of the more potent inhalation anesthetics to reduce the requirement for the other anesthetic.

Also indicated in low doses to provide analgesia in obstetrics and for procedures not requiring loss of consciousness.

Pharmacology/pharmacokinetics¾ Minimum alveolar concentration (MAC) in oxygen:

> 100%.

Blood-to-gas partition coefficient (37 °C):

0.47

Oil-to-gas partition coefficient (37 °C):

1.4

Biotransformation:

None of dose metabolized.

Elimination:

Primary: 100% excreted unchanged by exhalation.

Other actions/effects:

Blood pressure generally unchanged.

Heart/pulse rate increases.

Constriction of peripheral vasculature.

No dose-related muscle relaxation.

Precautions¾ Pregnancy:

Studies in animals have shown that nitrous oxide causes fetal death, growth retardation, and skeletal anomalies.

Drug interactions and/or related problems:

In addition to the increased CNS depressant, respiratory depressant, and hypotensive effects that may occur when an anesthetic is used concurrently with any CNS depressant, concurrent use of high doses of fentanyl or its derivatives with nitrous oxide may decrease the heart rate and cardiac output. These effects may be more pronounced in patients with poor left ventricular function.

Medical considerations/contraindications:

Caution needed in the presence of air-enclosing cavities (such as pulmonary, renal, or occluded middle ear air cysts or air embolism), acute intestinal obstruction, or pneumothorax, or during or recently following the procedure of pneumoencephalography, as nitrous oxide may increase pressure within rigid-walled cavities or volume within nonrigid-walled cavities.

Additional Dosing Information

Nitrous oxide must be administered with at least 30% of oxygen to reduce the risk of hypoxia.

For anesthesia

Premedication of the patient with an opioid analgesic or a barbiturate may be necessary in order to achieve induction of anesthesia.

Nitrous oxide may diffuse into the cuff of an endotracheal tube; periodic deflation of the endotracheal tube is recommended during administration.

The concentration administered during maintenance of anesthesia must be individualized, depending upon the condition of the patient and the type and quantity of supplemental medications administered.

When prolonged administration of nitrous oxide is discontinued, 100% oxygen should be administered briefly to reduce the risk of diffusion hypoxia

doctorgirl78 · Credits: 5316 My Scrapbook

i found the reference for n2o increasing pul pressure.............in nov 2002 AIIMS book by RxPG

thakurda · Credits: 1233 My Scrapbook My Reading List 42 Books

N2O more information

1. can cause abortion in health providers if exposed for long periods

2. higher female chilld birth even in non medical wives of anaesthetists otherwise not exposed to N2O

qudrat · Credits: 153 My Scrapbook

N2O is potent analgesic and weak anaesthetic
can reduce the reqiurment of other inhalational agent.
Has greater mac value

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