Physiology Flashcards
67 year old man who has smoked since his teens has been diagnosed with COPD. His disease is stable. His FEV1/FVC% is likely to be…
- 90%
- 40%
- 80%
- 60%
- 20%
60% (diagnositc criteria for COPD is <70%)
Which of the following is correct in a patient with emphysema?
- gas exchange is unaffected
- the work of breathing is decreased
- pulmonary compliance is increased
- total lung volume is decreased
- FEV1/FVC ratio is increased
pulmonary compliance is increased
Which of the following is correct in a patient with COPD?
- inspiration will be more difficult than expiration
- dynamic airway compression is likely to occur during active expiration
- the presence of emphysema will help alleviate dynamic airway compression
- oxygen saturation should be maintained near 100% if the patient is retaining CO2
- dynamic airway compression is likely to occur during inspiration
dynamic airway compression is likely to occur during active expiration
Active expiration increases the intraplural pressure, which compresses airways and allows for expulsion of residual air
21 year old woman sees her GP about intermittent breathlessness. She often feels breathless when she’s in a crowded room. When she feels breathless she also notices numbness and tingling around her mouth. Hb is normal. What is the most likely mechanism?
- increased work of breathing due to reversible airway obstruction
- increased central and autonomic arousal
- reduced oxygen carrying capacity of the blood
- stimulation of peripheral chemoreceptors
- reduced surface area for gas exchange
increased central and autonomic arousal
Not breathing enough oxygen results in increased CO2, which causes tingling and excessive exhaling to compensate
In a patient with pulmonary fibrosis, the FEV1/FVC% is likely to be…
- 35%
- 40%
- 80%
- 60%
- 20%
80% - ratio is not affected because fibrosis doesn’t change FEV1, if anything it would decrease the FVC and cause a higher %
Previously fit 22 year old man as been unwell for 2 days. He presents with cough productive of greenish sputum, fever a SOB. His PO2 is 8.2 kPa. What is the saturation likely to be?
- 98%
- 90%
- 82%
- 75%
- 60%
90% - even though the PO2 is low, saturation will remain high
52 year old man with SOBoE was diagnosed with diffuse pulmonary fibrosis. His ABG results under resting conditions showed a PO2 of 10.2 kPa, %saturation of 97%, and PCO2 of 4.9 kPa. His Hb is 10.5.
Normal values: PCO2 4.7-6.1, PO2 12.0-14.7
Which of the following results would you expect for him during climbing the stairs?
- %Saturation 90%, PO2 8.3, PCO2 4.8
- %Saturation 97%, PO2 11.3, PCO2 5.9
- %Saturation 98%, PO2 12.6, PCO2 3.4
- %Saturation 90%, PO2 9.4, PCO2 6.7
- %Saturation 95%, PO2 8.3, PCO2 7.1
%Saturation 90%, PO2 8.3, PCO2 4.8
PF mainly affects the diffusion of gases because of the thickened membrane
CO2 diffuses more readily than O2 (x20 more readily). O2 will drop more, as will saturation (so, 2nd and 3rd option can be eliminated)
Of the remaining choices, only the 1st option has a normal PCO2
A 32 year old woman with type 1 diabetes that is usually well-controlled is admitted with a 2 day history of dysuria, urinary frequency and vomiting. On arrival she is comatose, with deep sighing respiration and a temperature of 38.2 degrees.
Normal values: pH 7.35-7.45, PCO2 4.7-6.1, HCO3 24-30, PO2 12.0-14.7
- pH 7.26, PCO2 3.2, HCO3- 8, PO2 12
- pH 7.08, PCO2 5.2, HCO3- 8, PO2 11.8
- pH 7.1, PCO2 7.1, HCO3- 26, PO2 10.2
pH 7.26, PCO2 3.2, HCO3- 8, PO2 12
Deep sighing breaths - compensation, PCO2 is being blown off and lost, and so will be low (option 3 can be eliminated)
DKA - low base excess and metabolic, not respiratory
Which of the following is correct about Functional Residual Capacity?
- usually increased in obese subjects
- measured by spirometry
- decreased in COPD
- is normally about 20% of total lung capacity
- is approx. 2.2 litres in a young adult man
is approx. 2.2 litres in a young adult man
Which of the following is correct about normal lungs?
- a low PO2 causes pulmonary vasoconstriction
- larger airways are supplied by pulmonary circulation
- beta 1 agonists cause bronchodilatation
- parasympathetic stimulation causes bronchodilatation
- the surface area for gas exchange remains constant in the absence of disease
a low PO2 causes pulmonary vasoconstriction - if the PO2 is low, extra blood going there would be wasted, the body tries to match O2 to blood supply for efficient perfusion
Beta 2 agonists cause dilatation
Parasympathetic stimulation causes bronchoconstriction
Surface area varies e.g. in exercise, alveoli expand and cardiac output increases
35 year old man is diagnosed with severe anaemia. What is his saturation and PO2 likely to be if he is breathing air?
(Normal values: PO2 12.0-14.7)
- Saturation 90%, PO2 9.2 kPa
- Saturation 99%, PO2 13.1 kPa
- Saturation 88%, PO2 13.1 kPa
- Saturation 99%, PO2 8.6 kPa
- Saturation 95%, PO2 16.9 kPa
Saturation 99%, PO2 13.1 kPa
Even though Hb is low, what there is will still be fully saturated so the % doesn’t change (leaves 2nd and 4th option)
PO2 is unaffected by anaemia, only CO2 is affected (lowered)
48 year old man is admitted with acute anterior MI. You have been called to see him during the night as he wakes up suddenly feeling SOB. When you arrive he is sitting up and the nurse has started high flow O2. O/E he has mild tachycardia and chest crackles posteriorly
- IV furosemide and oral digoxin
- IV furosemide and start nitrate infusion
- IV furosemide and betablocker
- IV furosemide and start calcium channel blocker
- IV furosemide and start ACE inhibitor
IV furosemide and start nitrate infusion
Patient is presenting with paroxysmal nocturnal dyspnoea. BMJ sates O2 therapy + IV loop diuretic to deal with pulmonary oedema, and vasodilators (nitrites) to reduce preload on heart
Digoxin has lots of nasty side effects and doesn’t act immediately
Beta blockers will make it worse in the short term!
CCBs aren’t given in heart failure
ACE inhibitors are good in the long run but this is an acute setting
Previously fit 74 year old lady complains of SOBoE for several weeks. She thought she had lost some weight despite eating well. O/E her pulse is irregularly irregular at 110 bpm, tremor of hands and a normal cardiac auscultation. Best investigation?
- FBC
- Echocardiogram
- CXR
- Thyroid function test
- Troponin T
Thyroid function test - answers all the questions posed here
FBC doesn’t give enough info
Echo alone wouldn’t explain all the symptoms (tremor?)
28 year old woman with a long history of anxiety presents complaining of tingling around her mouth and fingers. Most likely ABG?
- pH 7.6, PCO2 2.6, HCO3- 26, PO2 12.8
- pH 7.56, PCO2 3.0, HCO3- 26, PO2 6.6
pH 7.6, PCO2 2.6, HCO3- 26, PO2 12.8
Hyperventilation - more CO2 is blown off than the body can produce (so CO2 is low), however it is long-standing and the body can compensate (HCO3- is normal, as is PO2)
Respiratory alkalosis
26 year old man is brought to A&E department unconscious.
Noted to have needle puncture marks on both arms. RR is 8 and he has pinpoint pupils. Most likely ABG?
- pH 7.34, PCO2 6.5, HCO3- 38, PO2 6.1
- pH 7.34, PCO2 6.5, HCO3- 38, PO2 11.2
- pH 7.1, PCO2 7.1, HCO3- 26, PO2 6.1
pH 7.1, PCO2 7.1, HCO3- 26, PO2 6.1
First option is typical of COPD, and second is typical of COPD if given O2
Patient is in acute respiratory depression meaning it will be A or C
If the cause is respiratory, there will be a metabolic compensation but this takes days therefore it isn’t A
Acidosis presents because the patient is not breathing off CO2 so it remains high
Treatment in this instance (likely opioid overdose) is naloxone
