Which one of the following acute physiological cardiovascular effects occurs
in obstructive sleep apnoea?
A. Decreased left ventricular afterload
B. Decreased venous return to the right ventricle
C. Increased left ventricular preload
D. Increased stroke volume during apnoea
E. Increased sympathetic activity
E. Increased sympathetic activity
The role of oxygen in cellular respiration is:
A. The metabolism of glucose to acetyl CoA
B. A cofactor in the citric acid cycle
C. The terminal electron acceptor in the electron transport chain
D. The production of ATP by glycolysis
E. Conversion of pyruvate to lactate
C. The terminal electron acceptor in the electron transport chain
Acute physiological effects on the cardiovascular system during OSA
Exaggerated negative intrathoracic pressure with airway obstruction
results in:
• Initial inhibition, then progressive increase in sympathetic outflow
• Increased venous return to the right ventricle
• Decreased left ventricular preload
• Increased left ventricular afterload
• Decreased stroke volume during apnoea
• Increased stroke volume with relief of obstruction.
- Hypoxia resulting in:
• Either vagal (without airflow) or sympathetic stimulation (with airflow)
• Ischaemia that leads to reperfusion injury of endothelial cells. - Arousal from sleep resulting in increased sympathetic activity.
- Variations in blood pressure:
• During apnoea, blood pressure decreases with varying effect on heart rate
• Following apnoea, blood pressure and heart rate increase significantly.
The following chronic physiological effects of OSA are also observed:
• Increase in 24-h sympathetic nervous system activity
• Decrease in heart rate variability
• Endothelial damage and dysfunction
• Platelet activation and increase in blood coagulability
• Insulin resistance.
Treatment of OSA with continuous positive airway pressure (CPAP) has been
shown to improve hypertension and left ventricular ejection fraction in those with
congestive cardiac failure.
Which one of the following does not preclude an attempt at curative lobectomy for bronchogenic non-small cell lung carcinoma?
A. Pulmonary osteoarthropathy
B. Hoarseness of voice
C. Superior vena cava obstruction
D. Blood-stained pleural effusion
E. Preoperative forced expiratory volume in 1 s (FEV1)of 1.0 L
A. Pulmonary osteoarthropathy
- Pulmonary osteoarthropathy is a paraneoplastic manifestation that does not reflect the operability of a bronchogenic carcinoma.
- When a patient develops obstruction of the superior vena cava or hoarseness of the voice, the disease has become locally advanced with invasion of adjacent structures, and this usually indicates inoperability
- Performing a lobectomy or pneumonectomy on a patient with very poor pulmonary function reserve would be risky and this may also be indicative of advanced disease. Guidelines from the American College of Chest Physicians and the British Thoracic Society suggest that patients with a preoperative FEV1 of greater than 1.5 L are generally able to tolerate lobectomy.
- A blood-stained pleural effusion indicates pleural involvement and makes any attempted resection merely palliative.
The options for management of patients with poor lung function may include bronchoplastic and angioplastic sleeve resections, and sublobar resection (wedge resection or segmentectomy) is occasionally offered. With advances in stereotactic
radiotherapy and with the introduction of radiofrequency ablation, patients with poor lung function can be offered a wider range of therapeutic modalities
What causes mesothelioma
There are two principal forms of asbestos: long, thin fibres known as amphiboles (blue asbestos) and feathery fibres known as chrysotile (white asbestos).
Amphibole fibres are the major cause of mesothelioma but chrysotile fibres may also be oncogenic
What are the following associated with
- Silica
- Beryllium
- Cadmium
- Coal dust
- Copper
Silica: TB
Beryllium: which is used in the aerospace industry and in beryllium copper alloy machining, can cause granulomatous disease.
Cadmium, which is used in electronics, metal plating and batteries, can cause emphysema.
Coal dust causes emphysema with nodular fibrosis.
Copper causes nasal ulceration and perforation of the septum.
Which one of the following antibiotics has been found to have potential
immunomodulatory benefits in the treatment of non-cystic fibrosis bronchiectasis?
A. Azithromycin
B. Tobramycin
C. Amoxycillin with clavulanic acid
D. Vancomycin
E. Metronidazole
A. Azithromycin
Causes of pneumothorax
Traumatic vs Spontaneous (primary vs secondary)
- Pneumothoraces are classified as either spontaneous or traumatic - Traumatic pneumothoraces result from direct or indirect injury to
the chest and are further classified as iatrogenic or non-iatrogenic. - Spontaneous pneumothoraces are further classified into primary (no obvious lung disease is identified) and secondary (as a result of a clinically apparent lung condition).
PRIMARY
- Primary spontaneous pneumothorax is common in young men, aged between 10 and 30 years, who are thin and tall, and is rarely observed in persons older than 40 years old.
- Other risk factors for spontaneous pneumothorax include a history
of smoking and a family history of spontaneous pneumothorax.
- Although in patients with primary spontaneous pneumothorax there is no clinically apparent pulmonary disease, subpleural BULLAE are found during video-assisted thoracoscopic
(VAT) surgery in 76–100% of patients and in virtually all patients during thoracotomy.
SECONDARY
- Chronic obstructive pulmonary disease (COPD) and Pneumocystis jiroveci pneumonia related to human immunodeficiency virus (HIV) infection are the most common conditions associated with secondary pneumothorax.
- COPD patients with a forced expiratory volume in 1 s (FEV1) of less than 1 L are at the highest risk of secondary pneumothorax.
Patients who present with tachycardia of more than 135 beats/min, hypotension or cyanosis should raise the suspicion of a tension pneumothorax.
A 72-year-old woman with a known history of sarcoidosis presents with hypercalcaemia (total calcium 3.10 mmol/L; reference range: 2.10–2.55 mmol/L) and renal impairment (creatinine 219 μmol/L; reference range: 50–100 μmol/L).
Which one of the following best explains the mechanism of hypercalcaemia in sarcoidosis?
A. Chronic renal failure with secondary hyperparathyroidism
B. Increased formation of 1, 25-alpha hydroxy vitamin D
C. Milk alkali syndrome
D. Immobility
E. Ectopic calcitonin formation
B. Increased formation of 1, 25-alpha hydroxy vitamin D
- In sarcoidosis, hypercalciuria and hypercalcaemia are common
- There is enhanced 1-alpha hydroxylation of 25-hydroxy vitamin D by macrophages in granulomatous tissue (also seen in other granulomatous conditions) generating active 1, 25-hydroxy vitamin D.
- This promotes intestinal calcium bone absorption and increases bone resorption.
32. A 25-year-old pregnant woman was found to have pulmonary embolism on investigation for dyspnoea during her third trimester (week 39). Which one of the following treatment options is the most appropriate in this setting? A. Warfarin B. Low molecular weight heparin C. Aspirin D. Intravenous unfractionated heparin E. Graduated compression stockings
D. Intravenous unfractionated heparin
- Pregnancy is a hypercoagulable state. The risk of venous
thromboembolism (VTE) in pregnant women is four times as great as the risk in the non-pregnant population. - Warfarin crosses the placenta and the use of warfarin between 6 and 9 weeks of gestation is associated with midface hypoplasia,
stippled chondral calcification, scoliosis, short proximal limbs and short phalanges. - Fetal intracranial haemorrhage has been reported in the second and early third trimesters. As a result, warfarin is contraindicated in pregnancy.
- Low molecular weight heparin could be used during pregnancy for treatment as well as prophylaxis for VTE. However, this woman is very close to the time of delivery and the timing of delivery is very unpredictable. Intravenous unfractionated heparin is the
agent of choice because of its reversibility. Once the woman has gone into active labour, the heparin should be stopped and reversed with protamine if necessary to avoid excessive bleeding related to labour, induction of labour or Caesarean
section.
Indication for O2 therapy in COPD
Indications for long-term oxygen therapy include
- chronic hypoxaemia with PaO2 of 55 mmHg or less or arterial oxygen saturation of 88% or less or chronic hypoxaemia with a PaO2 of 55–60 mmHg in the presence of right-sided heart failure or polycythaemia.
Which one of the following is a major risk factor for chronic allograft dysfunction due to bronchiolitis obliterans after lung transplantation? A. Silent aspiration B. Acute cellular rejection C. Use of azithromycin D. Cyclosporine E. Nissen fundoplication
B. Acute cellular rejection
Bronchiolitis obliterans syndrome is the result of inflammation and scarring following lung transplantation.
Additionally, lung transplant patients are at risk of developing the condition if their body rejects the new organ and about 50% of lung transplant recipients develop the condition within five year
Bronchiolitis obliterans is a fibroproliferative process that narrows and
ultimately obliterates the lumens of small airways, resulting in progressive and largely irreversible airflow obstruction
Causes of pulsus paradoxus
Pulsus paradoxus, also paradoxic pulse or paradoxical pulse, is an abnormally large decrease in stroke volume, systolic blood pressure and pulse wave amplitude during inspiration. The normal fall in pressure is less than 10 mmHg. When the drop is more than 10 mmHg, it is referred to as pulsus paradoxus.
Causes pulmonary embolism. tension pneumothorax. asthma (especially with severe asthma exacerbations) chronic obstructive pulmonary disease
