This protocol addresses Pneumocystis pneumonia in patients whose gas-exchange impairment at rest meets the threshold for moderate-to-severe disease — a clinically important distinction that directly determines the route and intensity of treatment.
Moderate-to-severe PCP is defined by an alveolar-arterial (A-a) oxygen gradient >4.7 kPa together with a resting arterial oxygen tension (PaO2) <9.3 kPa breathing room air. Patients meeting these criteria require inpatient management and intravenous therapy rather than oral outpatient treatment.
Moderate-to-severe PCP requires hospital admission and intravenous therapy, with transition to oral administration once clinical improvement is established. Adjunctive corticosteroids are added to the regimen and must be started as early as possible — and no later than 72 hours after initiating anti-Pneumocystis treatment. Supplemental oxygen is provided to hypoxaemic patients. The complete agent selection, dosing schedule, and full treatment algorithm are available in the structured protocol.
Maintain SaO2 ≥90% or PaO2 ≥8.0 kPa. Oxygenation and clinical response are formally reassessed between days 4 and 8 of treatment.
The severity of PCP can be classified as mild-to-moderate if ≤4.7 kPa or moderate-to-severe if >4.7 kPa (Table 1).
Patients with moderate-to-severe PCP (i.e. PaO2 <9.3 kPa at rest breathing room air) should receive intravenous therapy in hospital and can later be switched to oral therapy to complete treatment.
Adjunctive corticosteroids are also given to those with moderate-to-severe PCP.
Benefit has been demonstrated only if corticosteroids are started within 72 hours of initiating specific anti-Pneumocystis therapy.
Supplemental oxygen given either via a tight-fitting facemask or using high-flow nasal oxygen should be given to hypoxaemic patients with PCP in order to maintain SaO2 90% or PaO2 8.0 kPa.
We suggest waiting at least 4 days before switching therapy in the absence of clinical improvement (Grade 2C).
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