NBME 21 Absorption atelectasis (NBME Answers)

Retired NBME 21 Answers

nbme21/Block 1/Question#5 (reveal difficulty score)
A 45-year-old woman is brought to the ...
Absorption atelectasis 🔍 / 📺 / 🌳 / 📖
tags: pulm repeat

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submitted by ∗nosancuck(102)

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Bruh let me tell you a lil secret

PEEP prevents Atelectasis AKA dat LUNG COLLAPSE

Dont be worryin about random words they puts in front of the HIGH YIELD ones

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hungrybox literally LOL'd lmao I love this +17

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submitted by ∗haliburton(224)

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wikipedia (apologies): The atmosphere is composed of 78% nitrogen and 21% oxygen. Since oxygen is exchanged at the alveoli-capillary membrane, nitrogen is a major component for the alveoli's state of inflation. If a large volume of nitrogen in the lungs is replaced with oxygen, the oxygen may subsequently be absorbed into the blood, reducing the volume of the alveoli, resulting in a form of alveolar collapse known as absorption atelectasis.

I chose cardiogenic edema, but I believe this is incorrect because there is no heart failure risk at this time, so the purpose of the PEEP is certainly not to push out fluid.

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bighead478 doesn't there have to be an airway obstruction (mucus, foreign object etc.) in order for this to happen? 100% O2 without any airway obstruction should not cause absorption atelectasis, right? +1

iloveallpotatoes And Tension Pneumothorax is wrong bc PEEP would furthur exacerbate that. +2

hyperfukus @iloveallpotatoes yea i realized that now after getting it wrong :( +1

plzhelp123 @bighead478, they are using a cuffed endotracheal tube and mechanically ventilating this patient which is creating an iatrogenic "obstruction" and as @haliburton mentioned, having a high FiO2 leads to over-absorption by the blood which leads to absorption atelectasis if no other gas is allowed to enter/there is no communication with atmospheric pressure during expiration. Thus, we add positive end-expiratory pressure which keeps alveoli open at the end of expiration to prevent collapse +1

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submitted by ∗chandlerbas(118)

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bronchus obstruction traps oxygen in alveoli no nitrogen able to enter (atmospheric air entering body (78% nitrogen and 21% oxygen, nitrogen is so important nitrogen bc it is a poorly absorbed gas and thus is in charged of keeping alveoli inflated) oxygen in the alveoli is absorbed into the blood reducing the volume of the alveoli alveolar collapse absorption atelectasis

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bethune Why is pulmonary hypertension incorrect? +1

samsam3711 PEEP allows the alveoli to remain slightly open with exhalation to prevent atelectasis. Pulmonary Hypertension is going to be related to vascular changes (instead you might see shunting of blood in areas of poor ventilation) +2

drzed Pulmonary HTN occurs because of pulmonary vessel vasoconstriction. This can occur d/t multiple factors, but one of the most important ones is hypoxic vasoconstriction that the lungs will undergo (for example, at altitude). In the setting of PEEP, you are ventilating the lungs perfectly; this allows for the pulmonary vessels to open up and not undergo vasoconstriction. Thus, you prevent pulmonary hypertension via hypoxia. +1

peridot @drzed by your logic, you're arguing for D to be the answer but the correct answer was about preventing atelectasis +1

medstudent The question is what’s key. The purpose of PEEP is to keep the airway open. The purpose of ventilation with supplemental oxygen can help with preventing pulm HTN. Could be wrong, but that’s what makes sense to me. +1

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submitted by ∗namesthegame22(14)

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Oxygenation of mechanically ventilated patients in the setting of acute lung injury is challenging because of reduced lung compliance and absorptive atelectasis from fluid in the alveolar space.

Positive end-expiratory pressure (PEEP) can reduce the amount of alveolar collapse and atelectasis.

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