Everything Flashcards
What is the mechanism for toxic sideffects of Nitrous Oxide?
Blocks Vitamin B12 dependent enzymes, such as thymidylate synthase (DNA synthesis) and methionine synthase (myelin formation).
What are the side effects of nitrous oxide?
Bone marrow suppression, peripheral neuropathies.
What type of patients should you not give nitrous oxide to?
Pregnant patients (possible teratogenic).
What conditions are hazardous to use nitrous oxide in?
Venous or arterial air embolism, pneumothorax, acute intestinal obstruction, intracranial air, pulmonary air cysts, intraocular air bubbles, and tympanic membrane grafting.
What effect does Isoflurane have on coronary arteries? Why could this be a problem?
It dilates coronary arteries, potentially creating a steal situation, where blood is diverted away from fixed stenotic lesions.
What effect does isoflurane have on the bronchi?
It is bronchodilatory.
How much faster is desflurane than isoflurane?
About 50% faster wake up time.
What is the blood gas partition coefficient of nitrous?
0.47
What is the blood gas partition coefficient of desflurane?
0.42
What can rapid increases in desflurane concentration lead to?
Elevated HR, BP, and catecholamine levels.
What can Desflurane, more than other volatiles, be degraded by dessicated CO2 absorbent into?
Carbon monoxide.
What are contraindications for volatile anesthetics?
Severe hypovolemia, malignant hyperthermia, and intracranial hypertension.
What is the solubility coefficient of sevoflurane?
0.65
Why is cardiac output not maintained as well with sevoflurane, as it might be with isoflurane or desflurane?
Because sevoflurane does not increase heart rate, so CO is not maintained.
What cardiac side-effect can sevoflurane have?
QT prolongation.
What increases the amount of Compound A produced by sevoflurane administration?
Increased temperature of gas, low flow anesthesia, high sevoflurane concentration, and anesthetics of long duration.
What enzyme metabolizes sevoflurane, and what multiplier is sevoflurane metabolized compared to isoflurane?
CPY-2E1, 10-25X more metabolized than isoflurane.
What is the possible complication of sevoflurane metabolism?
Possible rise in inorganic fluoride, which can cause renal injury.
What three factors affect inhaled anesthetic uptake?
Solubility, alveolar blood flow, and the difference between alveolar gas and venous blood gas partial pressure.
What factors affect speed of recovery and induction?
Elimination of rebreathing, high fresh gas flow, low anesthetic-circuit volume, low absorption by the anesthetic circuit, decreased solubility, high cerebral blood flow, and increased ventilation.
What are risk factors for halothane toxicity?
Multiple halothane anesthetics, middle aged obese women, persons with familial predisposition.
What effect does repetitive administration of barbituates have?
Saturates peripheral compartments, minimizing redistribution and making half-life dependent on elimination only.
What is the mechanism of action of barbituates?
Binding the GABAa receptor, increasing the duration of openings of a chloride-specific ion channel.
What determines the duration of effect of “sleep” doses of barbiturates?
Time to redistribution, for example, Thiopental will redistribute within 20 minutes.
What patient factors might barbiturates be a bad idea in?
Hypovolemia, B-blockade, and CHF, because you can get an uncompensated peripheral pooling of blood and direct myocardial depression, causing severe hypotension.
What effect do barbiturates have on the brain?
They constrict cerebral vasculature, causing a decrease in cerebral blood flow, cerebral blood volume, and decrease intracranial pressure.
What effect do barbiturates have on CPP?
Intracranial pressure decreases to a greater degree than arterial BP usually, so CPP increases.
What side-effect can barbiturates have on the liver?
They can promote aminolevulinic acid synthetase, which stimulates formation of porphyrin (heme intermediary). This can precipitate acute intermittent porphyria.