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 within the first 48 hours of admission. Hospital-acquired pneumonia (HAP) develops at least 48 hours after admission without mechanical ventilation, whereas ventilator-associated pneumonia (VAP) develops 48–72 hours after endotracheal intubation. 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, there is no current national CAP guideline; clinicians use ATS/IDSA recommendations with provincial stewardship advice and the local antibiogram. The RN’s immediate clinical task is to connect the pattern—work of breathing, oxygen requirement, mental status and perfusion—to urgency, then support timely, appropriately targeted therapy. Canadian RN authority to initiate a controlled act varies...