Pneumonia

Pneumonia is infection or inflammation of the lung parenchyma. Infected alveoli fill with inflammatory fluid and cells instead of air, so blood continues to pass through poorly ventilated regions. This intrapulmonary shunt explains both the crackles and the hypoxaemia; when the shunt is extensive, low-flow oxygen may not fully correct the saturation. The clinical setting narrows the likely organisms and the antibiotic strategy. Community-acquired pneumonia (CAP) begins outside hospital or is already present on admission. Hospital-acquired pneumonia (HAP) develops during a hospital stay in a patient who is not mechanically ventilated, whereas ventilator-associated pneumonia (VAP) develops in a patient who has been mechanically ventilated through an endotracheal tube. Aspiration may introduce gastric contents or colonised oropharyngeal secretions into dependent lung segments, but witnessed aspiration alone does not automatically require anaerobic antibiotics. For Canadian adult practice, clinicians commonly use the ATS/IDSA community-acquired pneumonia recommendations together with provincial or territorial stewardship advice and the local antibiogram, because Canadian pneumococcal resistance patterns differ from those of the United States (see Treatment and Pharmacology). The RN’s immediate clinical task is to connect the pattern—work...