Explain daily cystic fibrosis treatment and a new CFTR modulator to a parent — OSCE

Candidate instructions

You are the paediatric registrar in the cystic fibrosis clinic. A 7-year-old boy, homozygous Phe508del, has grown Pseudomonas for the first time and is about to start the CFTR modulator elexacaftor-tezacaftor-ivacaftor. His mother has ten minutes with you. She wants to understand, in plain language: (1) why he still needs all his daily physiotherapy, nebulisers and enzymes; (2) what the new modulator tablet does and whether it replaces everything else; (3) why the new chest bug needs treating now when he seems well; and (4) when she should seek help urgently. Explain with empathy, check understanding, and agree a plan. [8]

Encounter

Mother: "He does so much every day already — the physio, the puffers, the enzymes with food. Why all of it?" [8]

Registrar: "You are right that it is a lot, and it is completely understandable to ask why. In cystic fibrosis the mucus in the lungs is thick and sticky, so it does not clear itself the way it should. The physiotherapy loosens and clears it, the nebulisers thin it and add water back to the airways, and clearing that mucus every day is what stops infections taking hold. The enzymes with food help him absorb the fat and calories he needs, because good nutrition and good lungs go hand in hand." [8] [4]

Mother: "We are starting this new tablet. Does that mean he can stop all the rest?" [1]

Registrar: "That is a really important question. The new medicine is a genuine breakthrough — it works on the faulty protein that causes cystic fibrosis and can improve his breathing, reduce chest infections and help his weight. But it treats the root cause rather than the mucus that is already there, so at this stage it is added to his other treatments, not a replacement for them. We would only ever change his physio or nebulisers gradually, with the team, and never all at once on our own." [1] [8]

Mother: "The swab grew a bug called Pseudomonas, but he seems perfectly well. Why treat it now?" [11]

Registrar: "I understand — it feels odd to treat when he looks fine. But this is the first time we have found Pseudomonas, and there is a window where we can often clear it completely with a course of an inhaled antibiotic. If we wait, it can settle in for good and become much harder to shift, and long-term Pseudomonas is one of the things that harms the lungs over the years. Treating it now, while he is well, gives us the best chance of getting rid of it." [11] [8]

Mother: "How will I know if something is going wrong and he needs to be seen?" [8]

Registrar: "Here is the plan. Contact the CF team if his cough gets worse or changes, if he brings up more or greener phlegm, if he is more breathless, tired or off his food, or if he loses weight — those can be signs of a chest flare-up that we treat early. Come in urgently, or call an ambulance, if he coughs up a lot of fresh blood, or has sudden bad chest pain with breathlessness. And trust your instinct — if you are worried, ring us. Shall I write these down with the team's number?" [8] [11]

Mother: "Yes please. That helps me feel less overwhelmed." [1]

Registrar: "I will give you a written plan with the warning signs, how to start the eradication antibiotic and the new tablet, and our contact number, and we will review him soon. To check I have explained it clearly — can you tell me what the new tablet does, and the main things that would make you call us straight away?" [1]

Examiner debrief

A strong candidate explains in plain language why daily airway clearance, nebulisers and enzymes remain essential, frames the CFTR modulator as a breakthrough that treats the root cause but does not replace the other pillars, justifies immediate eradication of a first Pseudomonas isolate while the child is well using the window-of-opportunity concept, and gives specific safety-netting that separates the signs of a chest flare-up from the emergencies of massive haemoptysis and pneumothorax. They acknowledge the treatment burden with empathy, check understanding with teach-back, and provide a written plan and review. Pitfalls include implying the modulator lets the family stop physiotherapy and nebulisers, dismissing the mother's instinct to wait on the new bug, and vague advice such as "come back if worse". [8] [1]