Direct Retinal Imaging for Shock Resuscitation in Critical Ill Adults II (D-RISC II)

BackgroundShock involves microcirculatory dysfunction that is not suitably captured well by measurements of large vessels, such as systemic blood pressure. The outer retinal microcirculation (the choroid) can be measured non-invasively and may reflect dysfunction in other organs. We tested the feasibility of measuring the retinal choroid in an intensive care setting and explored associations between choroidal measurements and severity of disease. MethodsWe performed optical coherence tomography on patients admitted to the intensive treatment unit, and repeated imaging once 12-72 hours later. We measured choroidal anatomy using automated image segmentation, compared this to routine clinical data, and described change over time. ResultsOf fifteen patients recruited, 80% (12) had successful baseline imaging and 40% (6) of these had follow-up imaging within intensive care. At baseline, patients with thicker choroids and larger vascularity had larger cumulative fluid balance, and lower disease severity (Acute Physiology and Chronic Health Evaluation II) score, haematocrit, and albumin. A measurable suprachoroidal space was seen in 75% (9) patients and the size of this space tended to be larger in patients with lower heart rates. There was substantial intraindividual variation in choroidal measurements over time. CommentMeasuring the retinal choroid is feasible in patients with critical illness. Exploratory associations with systemic variables suggest that the choroid may provide information about the microvascular function of other major organs. Size and change of choroidal measurements may reflect perfusion pressure or vascular leak in response to inflammation.