Physiology Flashcards
FEV1/FVC ratio of _____ is needed to make a diagnosis of COPD
Below 70
In emphysema, the elastic recoil of the lungs is lost. This means it is EASY/DIFFICULT for the lungs to expand and EASY/DIFFICULT for the lungs to recoil
Easy to expand lungs
Difficult to recoil lungs
What is compliance?
How easy it is to stretch the lungs
If lung elasticity is lost, what does this mean?
Easy to stretch the lungs but difficult to recoil
Reduced pulmonary compliance means that it’s easier/harder to expand the lungs?
Harder
What is the cut off (in kPa) for the oxy-Hb dissociation curve which means that O2 sats will be above 90% saturated?
8 kPa or above
What diffuses more readily - oxygen or carbon dioxide?
Carbon dioxide diffuses 20 times more readily than oxygen
In a patient with anaemia, PO2 will be normal/reduced/increased?
Normal
In a patient with anaemia, the Hb saturation will be normal/abnormal? Why is this?
Normal
- there is less Hb available in anaemic patients however the Hb will be fully saturated so Hb saturation is not affected
A patient with anaemia has normal PO2 and normal Hb saturation. True or false?
True
62 yo male, who smokes since his teen age, complains of increasing SOB. Barrel shaped chest and hyper-resonant percussion note on both sides. What is the most appropriate pulmonary function test result?
A – decreased TLC, increased lung diffusion capacity, normal or increased FEV1/FVC ratio
B – increased TLD, decreased lung diffusion capacity, normal or increased FEV1/FVC ratio
C – increased TLC, decreased lung diffusion capacity, decreased FEV1/FVC ratio
D – decreased TLC, decreased lung diffusion capacity, normal or increased FEV1/FVC ratio
E – decreased TLC, increased lung diffusion capacity, normal or increased FEV1/FVC ratio
Answer: C
Reasoning:
This is suggesting emphysema
COPD is an obstructive lung disease
Obstructive pattern: Decreased FEV1/FVC ratio
48 year old man is admitted with acute anterior MI. He wakes up during the night and suddenly feels SOB. When you arrived he is sitting up and the nurse has started high flow oxygen. On examination he has mild tachycardia and chest crackles posteriorly. What is the one best set of medications to help relieve the acute SOB in this patient
A – IV furosemide + oral digoxin
B – IV furosemide + start nitrate infusion
C – IV furosemide + beta blocker
D – IV furosemide + CCB
E – IV furosemide + ACE inhibitor
Answer: B
Reasoning:
This is acute heart failure
IV furosemide treats pulmonary oedema
Whilst B-blocker and ACE inhibitor are treatments of heart failure, they are for long term use - not acute.
Nitrate infusion will cause vasodilatation. This reduces the preload and by doing this it reduces the back pressure on the lungs.
Beta blocker is good to use in acute heart failure. True or false?
False
- only use this short term
Which drug used in heart failure improves long term survival?
ACE inhibitor
26 yo man is brought to A+E department with unconsciousness. He is noted to have needle puncture marks on both arms. His RR is 8 per minute and he has pinpoint pupils. What is the most likely set of ABGs from these patients:
A – pH – 7.34, pCO2 – 6.5, HCO3 – 38, PO2 – 6.1
B – pH – 7.34, pCO2 – 6.5, HCO3 – 38, PO2, 11.2
C – pH – 7.1, pCO2 , 7.1, HCO3 – 26, PO2 – 6.2
Answer C
Reasoning:
Opioid overdose suspected. Patient is hypoventilating.
how would you manage a patient that presents with an opiate overdose?
Administer naloxone
If someone presents acutely, they are Very likely / Very unlikely to have metabolic compensation in their ABG? Why is this
Very unlikely
- it takes a while for metabolic compensation
Since COPD is a chronic problem, respiratory acidosis with a metabolic compensation is likely or unlikely?
Likely
- chronic, so metabolic compensation will occur
64 year old man who has been a smoker for 50 years, coughs up sputum every day and is usually breathless on minor exertion; he has to stop once in climbin one flight of stairs. He is admitted to hospital with symptoms of chest infection, and feeling breathless at rest. What is the most likely set of ABGs
A – pH 7.2 ; pCO2 6.8 ; PO2 8.2 ; HCO3 26
B – pH 7.36 ; pCO2 6.8 ; pO2 ; 12.2 ; HCO3 38
C – pH 7.36 ; pCO2 6.8 ; pO2 6.9 ; HCO3 38
D – pH 7.5 ; pCO2 3.4 ; pO2 6.9 ; HCO3 26
E – pH 7.5 ; pCO2 3.4 ; pO2 12.2 ; HCO3 26
Answer C
Reasoning:
High PCO2
High HCO3- to compensate
pO2 low because patient likely to be hypoxic
75 year old man with RLL bronchial carcinoma, who is on the practice palliative care register, is reviewed by his GP because of increasing breathlessness. His wife reports that happens more often when he is on his own and overnight. His pain is well controlled with a low dose of oral morphine twice daily. On examination there are a few course creps in the RLL. Which one of the following is likely to be most effective in treating dyspnoea in this patient. A – dexamethasone B – furosemide C – hyoscine D – lorazepam E – midazolam
Answer: D
Reasoning:
Happens when alone or overnight - suggests it only happens at certain parts of the day rather than all the time
65 yo woman is admitted complaining of SOB. She was well until 2 months before admission, when she developed a sore knee, for which she has been prescribed twice daily painkiller tablets. Her stools have recently been black and tarry. She feels very tired, and breathless on minimal exertion, but not at rest. On examination, her CVS is normal and chest clear. What is the most lieely physiological mechanism for her SOB?
A – reduced pulmonary compliance
B – reduced partial pressure of oxygen in the arterial blood
C – stimulation of central chemoreceptors
D – reduced oxygen carrying capacity of the blood
E – reduced diffusion of oxygen into the blood through the respiratory membrane
Answer D
Reasoning:
The patient is bleeding and doesn’t have as much Hb
