General Flashcards
Blood volume by age group
premie infant: 90-105 mL/kg full term baby: 80-90 mL/kg infant 3-12 mo: 70-80 mL/kg child 1-12: 70-75 mL/kg adult male: 65-70 mL/kg adult female: 60-65 mL/kg
Peds ETT formula
(age/4) + 4
With CHRONIC use, what inhaled anesthetic is MOST likely to impair DNA synthesis?
Des, N2O, Iso, Sevo?
N2O
Nitrous Oxide can irreversibly oxidize the cobalt atom of vitamin B12 to an inactive state –> inhibits methionine synthase –> prevents conversion of methyltetrahydrofolate to tetrahydrofolate which is required for DNA synthesis
Are carotid baroreceptors more sensitive than aortic arch baroreceptors?
YES
AA baroreceptors have higher pressure threshold –> less sensative
Where are the carotid baroreceptors located?
Bifurcation of internal and external carotid arteries
Can carotid chemoreceptors affect blood pressure?
yes, but their primary role is to alter respiration.
carotid body is a chemoreceptor located at the bifurcation of the carotid arteries. Measures pH, PaO2, PaCO2.
Modulates CV and resp functions thru sympathetic nervous system
What is the innervation of the carotid baroreceptor?
Of the carotid chemoreceptor?
Same innervation: sinus nerve of Hering, a branch of the glossopharyngeal.
How do the carotid baroreceptors respond to HTN?
decrease SVR.
Baroreceptors are PRESSURE sensors involved in feedback loop for arterial pressure regulation. Found in carotid bifurcation, also found in the aortic arch.
Most often activated when there is a change in BP >10%
Nitty gritty of how the baroreceptors actually work…
Changes (Increases) in arterial pressure cause walls to stretch, baroreceptors also stretch –> increase in parasympathetic NS. Both baroreceptors transmit signals to the solitary nucleus of the medulla.
Decreased bp = decreased stretch = decreased firing from baroreceptors. Also noted by the medulla —> decreased PSNS firing and increased SNS firing ( vasocontriction, increased HR, positive isotropy)
What does the solitary nucleus of the medulla regulate?
makers changes to BP via efferents that cause vasodilation, lower HR, and contractility.
A decrease in these efferent signals will attenuate these effects. decreased PSNS firing and increased SNS firing ( vasocontriction, increased HR, positive isotropy)
Where are there baroreceptors?
carotids, aortic arch, left atrium and ventricle, right atrium, PA, some venous systems
What happens during longstanding HTN with the baroreceptor response? Anything? Nothing?
Become accustomed to new set point of BP…so need other mechanism to regulate long-term BP homeostasis (hormonal and renal regulation)
Do baroreceptors react to changes in blood VOLUME?
the left atrium and ventricle baroreceptors do!
What do anesthetic agents do to carotid baroreceptors?
Can blunt their reactions in a dose-dependent fashion.
Means sympathetic NS responses are reduced.
