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Case 8: A wave worth catching. Argo. M. 8:22-6-26
A male in his 70s presented to ED Resus with severe shortness of breath. He had a 3 month history of breathlessness, treated as lower respiratory tract infection in the community.
His family called for an ambulance due to worsening symptoms of dyspnoea and appearing cyanosed. He had a relevant past medical history of Atrial fibrillation (on anticoagulation therapy), mitral valve replacement, aortic regurgitation and mild congestive cardiac failure.
His presenting observations were: RR35, 61% SATs on room air, 84% on 15L NRM, 120HR, 180/110 BP, GCS 15, 36.5T, BM 6.2.
Clinically he appeared to be in acute cardiac failure with evidence of peripheral and pulmonary oedema on his portable chest x-ray. He was treated with IV Furosemide diuresis and a GTN infusion to help offload fluid and reduce his preload. Despite this, he remained in considerable respiratory distress with a high oxygen requirement, not adequately saturating on 15L. The question arose, 'are the basal opacities on the chest x-ray moderately large pleural effusions amenable to drainage or is it consolidation or atelectasis?'
This is a scan using the linear probe in a longlitudinal plane visualising the pleural space between 2 ribs. M-mode is placed to interrogate the pleural space. The resultant image on the right is a fantastic demonstration of a Sinusoid Sign indicating a pleural effusion.
The Sinusoid sign indicates mobile fluid surrounding the lung - with respiration, the movement of the viseral pleural with inspiration and expiration can be visualised by the echogenic pleural fluid around it, which results in a vivid sinusoid wave pattern.
Sinusoid Sign = Pleural fluid.
The images above are taken using a curvilinear probe in the position of a FAST scan, looking at the right upper quadrant (RUQ) and left upper quadrant (LUQ) regions. Both scans show the diaphragm - above it is lung and below is the hepatorenal angle and splenorenal angles respectively. The red line runs along the abdominal thoracic spine with the individual echogenic vertebra.
In normal, healthy, ventilated lungs, the air in alveoli largely reflect and scatter ultrasound waves, preventing visualisation of deeper lung tissue and the thorcic spinal vertebra are not seen. As a result the image appears dominated by artefacts - an obscured light fuzzy image - this is normal lung. In this patient, the lung bases have a signifcant collection of hypodense (black) fluid (the blue line). This medium allows ultrasound waves to be transmitted down to the thoracic verbrea and we can see the thoracic spine indicated by the green arrow - this is called the Anterior Spine sign. In this context, this indicates the prscence of pleural effusions in both lung bases.
The patient went on to deteriorate - he required intubation and bilateral chest drains were inserted in ITU along with ongoing cardiac failure management.
Learning Points:
POCUS can be used to differentiate observations made on clinical examination and chest xrays, helping to identify pleural fluid collections.
The Sinusoid sign and Anterior Spine Sign may indicate the prescence of pleural fluid.
Trainee Lead Editor: Dr Amy Knowles, ST5
Checked: Dr Ahmed Abdul-Ghani, Lead Project Consultant
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