Respiratory Flashcards
The majority of carbon dioxide in blood is carried in the form of:
A. Carbamino compounds bound to Hb B. Bicarbonate ions C. Carbon monoxide D. Carbonic acid E. Dissolved in plasma
Answer: B - Bicarbonate ions
The majority of CO2 in blood is carried as bicarbonate ions (70-80%). The solubility in blood is about 20x greater than oxygen. Upon diffusing into the RBC, it is rapidly hydrated to H2CO3 by intracellular carbonic anhydrase - then it dissociates into H and HCO3.
Which one of the following statements concerning the diaphragm is correct?
A. It is innervated by the phrenic nerves that arise from C1-3
B. In diaphragmatic paralysis, the abdomen may be seen to move outwards on inspiration
C. A common cause of paralysis is cardiothoracic surgery
D. In bilateral paralysis the vital capacity is unaffected
E. Sleep disordered breathing is rare among patients with diaphragmatic dysfunction
Answer: C - A common cause of paralysis is cardiothoracic surgery
The diaphragm is innervated by C3-C5.
Normal contraction leads to an outward movement of the abdomen but in paralysis there is paradoxical inward motion during inspiration.
Phrenic nerve injury may occur in 2% of patients undergoing cardiothoracic surgery.
There will usually be moderate-severe restriction in total lung capacity in bilateral paralysis.
The oxygen dissociation curve is characterised by:
A. Shift to right by carbon monoxide
B. Shift to right by CO2, leading to enhanced O2 release
C. Shift to left by acidosis, leading to enhanced O2 release
D. Shift to left by 2,3 -BPG
E. Percentage saturation of Hb (y-axis) at various partial pressures of CO2 (x-axis)
Answer: B - Shift to right by CO2, leading to enhanced O2 release
Hot, high (2-3BPG) and acidic = right shift
CO & HBF = left shift
Which of the following acute physiological cardiovascular effects occurs in OSA?
A. Decreased LV afterload B. Decreased venous return to the right ventricle C. Increased left ventricular preload D. Increased stroke volume during apnoea E. Increased sympathetic activity
Answer: E - Increased sympathetic activity
The role of O2 in cellular respiration is:
A. Metabolism of glucose to acetyl CoA B. Cofactor in citric acid cycle C. Terminal electron acceptor in the electron transport chain D. Production of ATP by glycolysis E. Conversion of pyruvate to lactate
Answer: C - Terminal electron acceptor in the electron transport chain
Cellular respiration requires oxygen as the terminal electron acceptor to allow proton gradients and mitochondrial ATP generation.
Rapid eye movement (REM) behaviour sleep disorder is associated with:
A. No therapeutic response to Clonazepam B. Obstructive sleep apnoea C. Increased female incidence D. Epileptiform EEG trace E. An increased subsequent risk of Parkinsonism
Answer: E - An increased subsequent risk of Parkinsonism
REM sleep behaviour disorder is a parasomnia with vivid and often frightening dreams are acted upon.
Marked male predominance and can be an early feature of alpha-synucleinopathies e.g. PD, LBD or MSA.
Which of the following structures is devoid of cartilage?
A. Primary bronchus B. Larynx C. Respiratory bronchiole D. Trachea E. Segmental bronchus
Answer: C - Respiratory bronchiole
Respiratory bronchioles are devoid of cartilage
Vital capacity is the sum of:
A. Tidal volume and expiratory reserve volume
B. Tidal volume and inspiratory reserve volume
C. Tidal volume, inspiratory and expiratory reserve volume
D. Tidal volume and reserve volume
E. Inspiratory volume and expiratory reserve volume
Answer: C - Tidal volume, inspiratory and expiratory reserve volume
Vital capacity is the large volume of air that can be expired after maximal inspiratory effort.
The amount of air that moves into the lungs with each normal breath is the tidal volume.
Air left after the maximal expiration is the residual volume.
Air expelled by active expiration after normal passive expiration is the expiratory reserve volume.
Vital capacity is the total sum of TV, IRV and ERV.
Which one of the following changes in sleep pattern occurs in the elderly?
A, Longer duration of sleep at night B. Increased duration of non REM sleep C. Increased duration of slow wave sleep D. Increased sleep onset latency E. Decreased frequency of nocturnal awakenings
Answer: D - Increased sleep onset latency
Elderly persons achieve less total sleep compared to younger people. There are more awakenings/arousals/fragmentation.
Deep non-REM sleep tends to be reduced but REM is usually preserved.
In familial pulmonary arterial hypertension, which gene is commonly mutated?
A. Bone morphogenic protein receptor 2 B. Endothelin receptor type A C. Endothelin receptor type B D. Matrix protein fibrillin E. Polycystin
Answer: A - Bone morphogenic protein receptor 2 (BMPR2)
The majority of familial PAH are associated with mutations in the BMPR2 or ALK1 genes.
Note the matrix protein fibrillin is encoded by the FBN1 gene (Marfan syndrome)
A 40 year old man has experienced increased breathlessness on exertion over the last few weeks. His arterial blood gases whilst breathing room air are given below. What is the alveolar-arterial O2 gradient?
pH 7.47 PaCO2 49 PaO2 56 HCO3 33 Base excess 8.8 O2 saturation 89%
A. 33 B. 12 C. 56 D. 89 E. 8
Answer: A - 33
A-a gradient = [150 - (pCO2 / 0.8)] - PaO2
= 150 - (49 / 0.8) - 56
= 150 - 61.25 - 56
= 32.75
Which one of the following is associated with narcolepsy?
A. Increased daytime sleep latency B. Reduced levels of CSF hypocretin C. Improvement in symptoms with clonazepam D. Temporal lobe abnormalities E. HLA-B29
Answer: B - Reduced levels of CSF hypocretin
Narcolepsy is characterised by severe daytime somnolence and often cataplexy (involuntary sudden loss of muscle tone e.g. with emotional response).
Sleep monitoring shows rapid sleep onset (significantly reduced sleep latency) and rapid onset of REM. Onset is usually during teenage years/young adulthood.
There is an associated with loss of hypothalamic neurons secreting hypocretin, a wakefulness neurotransmitter.
A 72 year old man with CKD presents with 1 week of intermittent fevers, mild chest pain and dyspnoea. CXR shows a unilateral left sided effusion.
Which of the following is the least useful prognostic factor for his illness?
A. Serum urea B. Age C. Pleural fluid appearance D. Serum albumin E. Serum CRP
Answer: E - serum CRP
Serum CRP may provide some prognostic information but not established for this purpose
Outcome score in pleural infection: Renal (urea) Age Purulence of fluid Infection source (CAP vs HAP) Dietary factors (Albumin)
A 65 year old woman with severe kyphoscoliosis undergoes a preoperative PFT. Which one of the following components of the lung function test is likely to be impacted by the above disorder?
A. Increased total lung capacity (TLC)
B. Increased functional residual capacity
C. Increased maximal inspiratory pressure (MIP)
D. Decreased vital capacity
E. Reduced forced expiratory volume in 1s (FEV1) - to forced vital capacity (FVC) ratio
Answer: D - Decreased vital capacity
Kyphoscoliosis causes a restriction of lung function. There is a decrease in FVC and TLC in proportion to the deformity.
Omalizumab is the first monoclonal antibody used in the treatment of asthma. The mechanism of action of Omalizumab is best explained by:
A. Binding to IgE with reductions in serum IgE and reduced IgE binding to the IgE receptor on basophils and mast cells
B. Blockage of binding of leukotrienes to type 1 cysteinyl leukotriene receptor
C. Binding to tumour necrosis factor
D. Inhibition of IgE synthesis
E. Inhibition of degranulation of mast cells
Answer: A - Binding to IgE with reductions in serum IgE and reduced IgE binding to the IgE receptor on basophils and mast cells
Omalizumab is a humanised IgG monoclonal antibody that binds IgE. It is indicated for moderate-severe persistent asthma despite ICS/LABA +/- LTRA treatment. It requires elevation of serum IgE.
EMQ ABGs
A. pH 7.50 pO2 55 pCO2 33 HCO3 25 B. pH 7.50 pO2 100 pCO2 33 HCO3 25 C. pH 7.45 pO2 100 pCO2 24 HCO3 18 D. pH 7.40 pO2 100 pCO2 40 HCO3 25 E. pH 7.33 pO2 61 pCO2 75 HCO3 38 F. pH 7.20 pO2 54 pCO2 55 HCO3 16 G. pH 7.26 pO2 128 pCO2 16 HCO3 7 H. pH 7.15 pO2 96 pCO2 33 HCO3 11
Select the most appropriate ABG for each patient
- A 20 year old woman was brought in after ingesting a hundred 300mg aspirin tablets. She is semi-conscious but responding to painful stimuli. Her blood pressure is 125/80, HR 100bpm and RR 36/min.
- A 63 year old man has long-term COPD (reformed smoker) and is on domicilliary oxygen. He has previously been admitted to hospital with acute exacerbation of respiratory symptoms requiring NIV.
- A 19year old pregnant women with T1 diabetes presents with 2 days of polyuria, dysuria and general unwellness. There is a history of poor compliance with medical therapy. Examination is normal and her BP is 110/60.
Bloods show Na 135, K 4.8, Cl 101, HCO3 10, Urea 8.1, Creatinine 90, Glucose 24
- Answer: C - Salicylate intoxication causes a primary respiratory alkalosis from salicylate induced hyperventilation and a metabolic acidosis from overproduction of organic acids.
- Answer: E - chronic compensated respiratory acidosis
- Answer: G - DKA
Which one of the following features excludes a diagnosis of COPD?
A. FEV1/FVC <0.70 post bronchodilator B. FEV1/FVC >0.70 post bronchodilator C. Non-smoker D. Weight loss E. Improvement with pulmonary rehabilitation program
Answer: B - FEV1/FVC >0.70 post bronchodilator
