EMQs in Clinical Medicine.pdf - Peshawar Medical College

Emergency management: respiratory distress – answers 45
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intermittent positive pressure ventilation (NIPPV) in such patients has
been associated with a reduction in the number of patients requiring formal
intubation. This is advantageous because anaesthesia and intubation
can be very difficult in a patient with respiratory failure. NIPPV should
be tried unless the patient is in extremis. Successful NIPPV requires a
conscious and cooperative patient.
A 17-year-old woman presents with wheeze and marked perioral
swelling: PaO 2 7.0 kPa (on 28 per cent O 2 ), PaCO 2 4.1 kPa.
This is a classic presentation of acute anaphylaxis, e.g. a type I IgEmediated
hypersensitivity reaction. The symptoms and signs include
rash, oedema, tachycardia, hypotension and wheeze. Laryngeal oedema
giving rise to upper airway obstruction is particularly worrying because
it may impede endotracheal intubation.
Initial treatment of choice is 0.5 ml epinephrine (adrenaline) 1:1000 solution
(500 g) delivered intramuscularly which can be repeated in the
absence of clinical improvement or if deterioration occurs. Intravenous
epinephrine is dangerous and should be given slowly only in a dilution
of at least 1 in 10 000 in an immediately life-threatening situation, e.g.
frank cardiac arrest.
A 14 year old with asthma presents with an acute severe asthma
attack: PaO 2 10.0 kPa (on 28 per cent O 2 ), PaCO 2 8.0 kPa
The British Thoracic Society suggests that features of a severe asthma
attack include peak expiratory flow rate (PEFR) 50 per cent
predicted/best, respiration rate 25 breaths/min, pulse 110 beats/min
and inability to complete a sentence with one breath.
Markers of a life-threatening attack include a PEFR 33 per cent of predicted/best,
silent chest, cyanosis, poor respiratory effort, bradycardia,
arrhythmia, hypotension, exhaustion, confusion, PaO 2 8 kPa, acidosis
with pH 7.35, high PaCO 2 . Intubation and transfer to the ICU must be
considered if the patient is not responding to drug therapy.
This patient is both hypoxic and retaining CO 2 . This is a poor prognostic
sign because people with acute asthma usually have a low CO 2 . The presence
of a high CO 2 is associated with imminent respiratory collapse. Despite elevated
CO 2 , 100 per cent O 2 should be given because, in this patient, there is
no risk of respiratory depression resulting from a hypoxic ventilatory drive.
Between attacks the patient’s CO 2 should be within the normal range. It is a
common mistake to restrict oxygen to patients with asthma and a high CO 2 .
A 28-year-old man involved in a road traffic accident presents with
severe respiratory distress. Examination reveals decreased expansion
on the right side of the chest with mediastinal shift to the left.
Tension pneumothorax is a medical emergency and management should
not be delayed by obtaining a chest radiograph. Air is being drawn into
the pleural space with each inspiration but cannot escape during expiration.