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]