The F.A.S.T.E.R. trial. Focused assessment by sonography in trauma during emergency retrieval: a feasibility study

This feasibility study aimed to establish if retrieval physicians can overcome the transport environment and obtain F.A.S.T. (focused assessment by sonography in trauma) images of suitable quality during patient retrieval in rotary wing aircraft such that diagnostic interpretation of free intra-abdominal fluid or pericardial fluid would be possible.

During a 6-month trial period, one of three retrieval physicians attempted to obtain the standard four quadrant F.A.S.T. views using a portable ultrasound on patients they retrieved. Ultrasound images were obtained whilst in-flight in a rotary wing aircraft. Image adequacy was assessed by the retrieval physician and by an independent blinded physician using strict clinical criteria.

Thirty-eight patients were enrolled. Thirty-six patients had a complete F.A.S.T. scan attempted whilst a further two patients had their abdominal quadrants scanned without a pericardial view being attempted. Independent blinded physician review of scans agreed with the scanning retrieval physician that images were adequate for showing the F.A.S.T. quadrants appropriately in 143 of 150 quadrants imaged and inadequate in two. Blinded physician review disagreed with scanning physician regarding adequacy of image in 5 of 150 quadrants imaged. Scanning physicians were happy with adequacy of the view in all F.A.S.T. quadrants in 34 of the 36 patients in whom a complete F.A.S.T. was performed. Blinded physician review agreed in 30 of those cases.

The physicians performing the F.A.S.T. examination, all incorporate ultrasound into their daily clinical practice thereby maintaining their skill level. This is likely to contribute to the high level of view adequacy. Independent blinded image review controlled for bias regarding view adequacy. Disagreement between scanning physician and reviewing physician assessment of view adequacy in 5 of the 150 views obtained is likely to relate to the difficulties in interpreting still ultrasound images, compared to interpreting real time images at point-of-care. There were no machine limitations.

This study demonstrates that it is possible for critical care retrieval physicians to obtain adequate ultrasound F.A.S.T. images on patients using a portable ultrasound machine en-route to definitive care, in a rotary wing aircraft.