Chest physiotherapy involves techniques like percussion, vibration, and postural drainage to mobilize pulmonary secretions in patients who have difficulty coughing them up. It is indicated for conditions involving thick secretions like cystic fibrosis or bronchiectasis. The techniques are contraindicated in situations involving bleeding or instability. Assessment involves a physical exam and reviewing medications and imaging before techniques are applied in specific positions targeting different lung lobes and segments to drain secretions into larger airways.