Airway suction, oxygen devices and nebuliser technique: SAQ

This infant has bronchiolitis with hypoxaemia that is failing low-flow oxygen, and the immediate tasks are to clear the secretions, escalate oxygen to a stated target, and decide whether a bronchodilator is indicated and how to deliver it. Each step rests on understanding the device, not on ritual. [3]

Question 1 (10 marks)

Classify the oxygen delivery devices, explain why this infant is failing low-flow nasal cannula, and outline your stepwise oxygen escalation with a stated target SpO2. [1]

Oxygen devices sort into variable-performance and fixed-performance families. A nasal cannula, simple face mask and reservoir mask are variable-performance: the oxygen they deliver is diluted by entrained room air during inspiration, so the real FiO2 falls when the child breathes fast and deep, exactly as this tiring infant is doing. A heated humidified high-flow nasal cannula and a tracheal tube are fixed-performance, delivering a set FiO2 that does not depend on the child's breathing. [1]

This infant is failing nasal cannula for two reasons. The nasal cannula delivers only an estimated 24 to 40 percent FiO2, which is diluted further by the infant's rapid, deep, recessive breathing, and the nasal secretions of bronchiolitis block the obligate nose-breather's airway, so gas cannot reach the alveolus regardless of the flow. Clearing the secretions by gentle suction may itself raise the saturation. [3]

My target SpO2 for this acutely ill infant is 94 to 98 percent, stated out loud. I escalate up the ladder: confirm and adjust the low-flow oxygen first, then move to heated humidified high-flow nasal cannula at 1 to 2 L/kg/min with blended oxygen, because the PARIS trial showed high flow reduces intubation in bronchiolitis versus standard oxygen. If high flow fails, I escalate to non-invasive or invasive ventilation with intensive care. [1]

I reassess work of breathing, SpO2 and the infant's response after each step, and I call for senior and intensive care help early, because a low SpO2 that will not correct despite correct device therapy signals a cause that needs fixing, not simply more oxygen. [3]

Question 2 (10 marks)

Describe your suction technique for this infant, including monitoring and the complications you must avoid. Then describe how you would deliver a bronchodilator if wheeze were present. [3]

I pre-oxygenate the infant before suctioning and apply continuous heart-rate and SpO2 monitoring throughout, because suctioning provokes a vagal bradycardia and desaturation within seconds. I suction what I can see first: clear the mouth and oropharynx with a rigid Yankauer, and gently clear the nose, because this obligate nose-breather may improve dramatically once the nasal airway is opened. [3]

If nasopharyngeal suction is needed, I use a soft catheter sized to about half the airway lumen, advanced gently and never forced, and I limit each pass to about 5 to 10 seconds, withdrawing the moment the heart rate or SpO2 falls. I avoid deep, blind pharyngeal suction, because it has caused iatrogenic mediastinitis in bronchiolitic infants; the safe rule is to suction only what can be seen. [4]

For bronchodilator delivery, the first-line tool for a wheezy child who can use one is a spacer with a salbutamol metered-dose inhaler, given one puff at a time into the spacer with tidal breathing, because the Cochrane evidence shows it is as effective as a nebuliser and faster. I reserve a jet nebuliser for the infant who cannot use a spacer or who needs high-flow oxygen at the same time, driving the gas at 6 to 8 L/min and confirming the mask seals and the mist is visible. [2]

The decision to give a bronchodilator at all in bronchiolitis is itself conditional, but where wheeze suggests a reversible component, the delivery method matters: a calm, upright child breathing quietly receives the respirable fraction of droplets (1 to 5 micrometres), whereas a crying infant deposits the dose in the mouth. I reassess the work of breathing and SpO2 after the dose and document the response. [2]