Cough and exertional hypoxaemia on biologic therapy

Dry cough for ten days, feverishness, fatigue and rapidly progressive exertional breathlessness. He is comfortable at rest but now stops after 150 metres. No sputum, pleuritic pain or haemoptysis.

Infliximab every eight weeks, last dose three weeks ago, plus azathioprine 125 mg daily. No current steroid or antimicrobial prophylaxis. Pre-biologic records say ‘TB screening performed’ but the result is not visible. He was born in Poland and visited four months ago. Ask about HIV testing with consent, contacts, travel and vaccination.

Three-kilogram weight loss and two drenching night sweats. No Crohn’s flare, leg swelling, immobility, heart-failure symptoms, mould/bird exposure or recent antibiotics. These facts keep TB, malignancy, opportunistic infection, drug pneumonitis and PE in play.

He fears losing the only regimen that has controlled Crohn’s, admission and lost income. Explain that temporarily withholding treatment during serious infection assessment is not the same as permanently stopping it; coordinate the decision with gastroenterology.

Respiratory rate 22, oxygen saturation 94% on air, pulse 102, BP 118/70, temperature 38.3°C: NEWS2 5. He speaks in full sentences; chest auscultation and percussion are normal. No oedema, calf signs, lymphadenopathy, thrush, rash or focal source.

After 40 metres at his own pace, saturation falls to 87% and respiratory rate to 30; he recovers seated. Perform only with suitable supervision, stopping criteria, oxygen access and a chair. This confirms significant physiological impairment despite a clear chest.

Lymphocytes 0.6 ×10⁹/L, neutrophils 3.0, CRP 88, LDH 620, lactate 1.4. Blood gas shows type 1 respiratory failure with respiratory alkalosis. Chest radiograph shows bilateral symmetrical interstitial shadowing without lobar consolidation or cavitation.

Send blood cultures, respiratory viral testing and targeted opportunistic/TB samples before antimicrobials where this does not delay necessary treatment. He cannot produce sputum: involve respiratory/infection teams early for induced sputum or bronchoscopy as appropriate. Offer HIV testing with informed consent. Retrieve original TB-screening data; ‘screened’ is not a result.

This is diffuse pneumonitis with exertional hypoxaemia in combined immunosuppression. Opportunistic infection, including Pneumocystis, is a leading concern; TB is a must-not-miss alternative because anti-TNF therapy increases progression risk. Viral/bacterial infection, drug-related pneumonitis, organising pneumonia, lymphoma and PE remain alternatives. The pattern is not itself diagnostic.

Admit, provide oxygen to the appropriate target, use infection-control precautions guided by risk, and involve respiratory, infection/microbiology and gastroenterology teams now. Hold the next immunosuppressive dose pending joint review rather than announcing permanent cessation. Assess for sepsis and deterioration repeatedly.

NEWS2 5 places him in the moderate-risk bracket, but immune impairment and clinical concern matter. NICE NG253 permits a senior clinician to consider using up to three hours to obtain information before broad-spectrum antibiotics in moderate risk; it does not mandate delay. Once the decision to treat is made, do not delay. Any high-risk feature or deterioration requires high-risk timing.

Obtain diagnostic respiratory material urgently because empirical corticosteroids can obscure or worsen competing diagnoses such as TB. Empirical therapy for suspected opportunistic infection and any adjunctive steroid decision require consultant-led, severity-specific management; do not publish a universal regimen from this scenario.

Manage as high-risk suspected sepsis: immediate senior/critical-care assessment, cultures and broad-spectrum IV antibiotics within the high-risk timeframe, while stabilising oxygenation and circulation.

Activate TB isolation, rapid resistance testing, TB/infection and health-protection pathways, withhold anti-TNF therapy and assess close contacts. Coordinate Crohn’s management with gastroenterology.

Treat as suspected neutropenic sepsis with immediate pathway antibiotics and urgent secondary-care management; azathioprine toxicity becomes a direct concern.

Reframe toward non-infectious pneumonitis, review antimicrobials rather than broadening indefinitely and coordinate respiratory/gastroenterology decisions on drug cessation, corticosteroids and whether tissue is required.

Strong: Integrates NEWS2, immune status, exertional hypoxaemia and trajectory.

Incomplete: Quotes NEWS2 without clinical context.

Unsafe: Discharges because the chest is clear and lactate normal.

Strong: Gets decisive samples urgently without missing the treatment clock.

Incomplete: Starts broad treatment with no diagnostic plan.

Unsafe: Delays all therapy for perfect samples.

Strong: Names opportunistic infection, TB and non-infectious pneumonitis with discriminators.

Incomplete: Says only ‘atypical pneumonia’.

Unsafe: Omits TB on anti-TNF therapy.

Strong: Explains a temporary hold and answers infection concerns honestly.

Incomplete: Mentions admission but not what happens to Crohn’s treatment.

Unsafe: Promises permanent continuation or cessation.