Background and purpose: This case report describes the physiotherapy assessments and interventions provided to a 56-year-old male in an Australian intensive care unit. The non-intubated patient suffered from respiratory deterioration, secretion retention, complete opacification of the left hemithorax on chest X-ray (CXR) and widespread coarse crackles on lung auscultation. The addition of lung ultrasound (LUS) facilitated more accurate diagnosis than what was formed on the basis of CXR and lung auscultation resulting in more effective treatment. Methods: The method used is a case report. Written consent was obtained from the patient for these data to be published. Summary: Secretion retention was initially suspected (based on clinical examination and CXR) and treated with airway clearance techniques, patient positioning and nasopharyngeal suction. Even though this assisted with secretion removal, the patient continued to have a high perceived work of breathing and increasing oxygen requirements. Physiotherapist performed LUS, under supervision, and revealed a large pleural effusion (1500mL), which was then drained by the medical team. Discussion: The addition of LUS to the critical care physiotherapist's assessment skills may provide clinical benefit. The increased diagnostic accuracy of LUS compared with other routine assessments warrants further investigation.