Regarding reexpansion pulmonary oedema following treatment of a spontaneous pneumothorax, all of the following statements are true EXCEPT:
Answer: A: Reexpansion pulmonary oedema is an infrequent but important complication that may occur following insertion of a chest tube for a large pneumothorax, especially when a patient presents late (after 72 hours from the onset). It is often described as occurring following rapid reexpansion due to application of suction, but it may occur without suction. Patients are usually younger patients. Clinical presentation is dyspnoea and hypoxaemia after the insertion of a chest tube and pulmonary oedema will be evident on the side of the penumothorax on a CXR. Unlike in cardiogenic pulmonary oedema, aggressive fluid resuscitation is part of the management. A severely hypoxaemic patient with florid pulmonary oedema who does not respond to oxygen therapy may require intubation and ventilation.
Reference:
Which ONE of the following factors is LEAST likely to predict the risk for a fatal or near-fatal episode of asthma?
Answer: D: A life-threatening admission with asthma in the previous 12 months predicts the risk of another near-fatal episode. In one study, two-thirds of patients who had an admission with life-threatening asthma had a further near-fatal or fatal attack within 12 months. Severe asthma is not usually associated with marked arterial desaturation. Arterial desaturation occurs late and indicates a life-threatening situation. Severe asthma is associated with an increased respiratory rate and resultant hypocarbia on blood gas analysis. As the patient tires and respiratory failure sets in, PaCO2 normalizes. This should be considered a danger sign that requires aggressive management. Current corticosteroid use increases the potential for the patient to respond less to the acute treatment for a severe episode. However, it is the least valuable predictor of a near-fatal episode.
Regarding bronchodilator therapy in severe asthma, which ONE of the following statements is TRUE?
Answer: C: In severe asthma, the current recommendation is to use inhaled salbutamol delivered either via an MDI with a large spacer or wet nebulization. The onset of action is 5 minutes and duration is 6 hours. However, ‘back to back’ nebulization, as opposed to intermittent nebulization, is routinely used in the ED because drug delivery to the bronchiolar site depends on the patient’s respiratory rate and the tidal volume. The patient inhales approximately only 33% of the dose placed in the nebulizer chamber and only 20% reaches the bronchioles because patients with severe asthma usually take small tidal volume breaths due to tachypnoea. Current evidence shows that intravenous bronchodilator therapy (as a bolus dose or as an infusion) with salbutamol does not offer additional clinical benefit over that offered by inhaled bronchodilator therapy. However, it is unclear whether there would be additional benefits in ventilated patients and the paediatric population. Intravenous salbutamol therapy should be considered when the critically unwell patient is unable to take inhaled therapy effectively, such as intolerance of inhaled therapy, but without indications for intubation. If inhaled therapy is not effective and there are indications for intubation it is prudent to intubate and ventilate the patient early. In ventilated patients inhaled salbutamol can be used with a nebulization port or an MDI port in the circuit. Nebulization with high oxygen/air flows in to the circuit may contribute to dynamic hyperinflation of the lungs in an asthmatic patient.
Although adrenaline infusion is used in severe asthma, especially in ventilated patients, currently there are no recommendations for its use. One advantage adrenaline has over salbutamol is its ability to reduce airway oedema because of its α-agonist effects. When severe asthma is complicated by hypotension (this should not be due to dynamic hyperinflation), adrenaline seems to be a reasonable option as a rescue agent. Continuous use of both salbutamol and adrenaline contributes to lactic acidosis in asthma patients.
References:
Regarding the use of magnesium sulphate in severe asthma, which ONE of the following statements is TRUE?
Answer: A: A single dose of intravenous magnesium sulfate is an effective adjunct in the treatment of severe asthma. The usual recommended dose in adults is 1.2–2 g and 50 mg/kg in children, given slowly via IV over 20–30 minutes. There is evidence to suggest that the response from the drug is greatest in patients with most severe airflow obstruction due to bronchospasm on presentation to the ED. Therefore, it is not recommended for routine use in mild to moderate asthma episodes. Even in severe asthma it does not reduce the rate of hospital admission, but it is associated with a significant improvement in lung function. Current evidence fails to show any clear benefit for use of nebulized magnesium sulfate in all age groups, whereas intravenous magnesium sulfate can be used in patients in all age groups with severe asthma.
Regarding intubation of a patient with severe asthma, which ONE of the following is the MOST appropriate option?
Answer: B: Intubation of a patient with severe or life-threatening asthma is a challenging situation. It requires carefully considering many factors and involving the most experienced airway operators. The absolute indications for intubation are:
In the presence of severe hyper-capnoea and acidosis in a patient with normal level of consciousness and who is not exhausted, further aggressive bronchodilator therapy should be continued prior to reconsidering intubation. These severely unwell patients are often volume depleted because of fluid losses through respiration and reduced intake. Induction agents may cause vasodilatation and loss of sympathetic tone, therefore causing severe hypotension at induction. Fluid resuscitation and careful adjustment of induction dose is therefore required. In the ED, ketamine at a dose of 1–2 mg/kg is considered by many as the induction agent of choice because it has sympathomimetic and bronchodilating properties.
It should be used with a paralytic agent such as suxamethonium to facilitate the easy passage of the tube. Brisk repeated bagging should be avoided because it results in increased intrinsic positive end-expiratory pressure (PEEP) due to dynamic hyperinflation of the lung that can contribute to hypotension.
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