All of the following clinical features may suggest hypercapnic rather than normocapnic COPD EXCEPT:
Answer: D: COPD patients in acute respiratory failure belong to one of two distinct clinical categories:
It is important to identify the patients who have a high risk of developing hypercapnic respiratory failure on presentation to the ED so as to prevent further deterioration of the condition with too aggressive oxygen therapy. In such patients, oxygen therapy should be continued in a controlled manner as clinically appropriate (e.g. up to 2 L/min via nasal prongs or via Venturi mask) and all nebulised bronchodilator therapy should be delivered using medical air.
Generally, COPD patients with chronic bronchitis tend to present with hypercapnic respiratory failure more than those with emphysema. Obese patients and those with obstructive sleep apnoea are more likely to develop hypercapnoea. Patients using central nervous system depressants such as sedatives and alcohol have a high risk of developing hypercapnic respiratory failure.
Patients with emphysema, thin physique, hyperinflated lungs and those exhibiting accessory muscle use and pursed-lip breathing are more likely to be normocapnic. Both categories of patients can have right heart failure (RHF) but hypercapnic patients are likely to develop RHF early.
Reference:
Regarding the investigation of patients presenting with an apparent exacerbation of COPD, which ONE of the following is TRUE?
Answer: B: In asthma, there is a significant reversible component of airways obstruction. In contrast, in COPD exacerbation, major reductions in peak flow and FEV1 measurements can be seen only in some patients. Because of the high negative predictive value of a very low BNP, acutely dyspnoeic patients with very low BNP values despite a moderate degree of clinical suspicion for congestive heart failure (CHF) should be considered to have COPD. Ultimately it is appropriate to perform chest CT when clinical suggestion of a pneumothorax remains and results of plain films and ultrasound are non-diagnostic. The presence of COPD may result in false-positives using bedside USS and the data in this setting are limited. A sufficiently sensitive D-dimer is suitable to exclude PE in patients with COPD who do not have a high clinical probability of PE. Patients with COPD have an elevated risk of venous thromboembolism and PE should be considered when an acute exacerbation is considered, especially if deterioration occurs rapidly with no other apparent cause.
Regarding the use of supportive ventilation in the management of patients presenting with an acute exacerbation of COPD, which ONE of the following is FALSE?
Answer: A: The use of NIV in patients presenting with an acute exacerbation of COPD, in addition to usual medical care, is associated with reductions in mortality, need for intubation and treatment failure. NIV should be considered early in the course of respiratory failure before severe acidosis ensues (in line with global and Australasian guidelines). This may reflect the benefit of starting earlier in the process when respiratory muscles are less fatigued.
Indications for NIV include:
There are no definite clinical predictors to identify which patients with respiratory failure will benefit from NIV. Patients with a pH between 7.25 and 7.30 appear to receive the greatest benefit.
References:
Regarding the management of patients presenting with an exacerbation of COPD, which ONE of the following is TRUE?
Answer: C: Although it is common practice to use anticholinergic and beta-sympathomimetic bronchodilator agents in combination for their synergistic effects, a recent review found that there was no significant difference between the agents, and the combination did not appear to increase the effect on FEV1 over either agent alone. However, the duration of action of anticholinergic agents is longer than short-acting β-agonists and they have a lower adverse effect profile. Depending on the clinical situation either types of agents can be used alone or in combination.
Bacteria play a role in approximately 50% of exacerbations. The presence of increased dyspnoea, increased sputum purulence or volume, leucocytosis or fever is a reasonable trigger for commencing antibiotics. Patients with more severe exacerbations are more likely to benefit from antibiotic treatment than those with less severe exacerbations. Antibiotics should be chosen to cover Strep. pneumoniae, H. influenzae, and Moraxella catarrhalis. Mycoplasma and Chlamydia pneumoniae are possible infections in some patients.
Systemic steroids hasten recovery as well as reduce hospital stay and early treatment failure in patients with acute exacerbations of COPD. The effects of inhaled corticosteroids on the course of an exacerbation are uncertain. The inpatient mortality is 17–30%, with the best predictors of successful weaning from ventilator being pre-existing functional status and FEV1.
All of the following factors contribute to increased mortality rate among haemodynamically stable patients with PE EXCEPT:
Answer: C: The International Cooperative Pulmonary Embolism Registry demonstrates a death rate of 15% for haemodynamically stable patients with PE and 58% for haemodynamically unstable patients. Among haemodynamically stable patients with PE, several factors have been shown to be associated with increased rate of death. A meta-analysis of several studies has shown that increased troponin levels (as a marker of myocardial dysfunction or injury) in haemodynamically stable patients with PE increases both short-term mortality risk and risk of death by PE by a factor of 5.2 and 9.4 respectively. Right ventricular (RV) dysfunction on echocardiography is another important factor associated with increased rate of death in these patients. In these patients RV hypokinesis and dilatation are shown to be independent predictors of 30-day mortality. In addition, RV septal bowing has been shown to be a predictor of death in a large retrospective study. However, application of these findings to the clinical setting in the ED is controversial because RV assessments were done using computerized reformatted images and hence not available to bedside echocardiography. However, RV dysfunction as visualized on CTPA has been suggested as an independent predictor of 30-day mortality. The subgroup of patients who have both RV dysfunction on echocardiography and elevated troponin levels seem to have a significantly higher risk of death. Other factors that have been shown to be associated with increased mortality in haemodynamically stable patients are:
There is no clear evidence for increased risk of death in pregnancy but they may be more prone to have other adverse outcomes directly related to PE or anticoagulation.
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