Ophthalmic assessment and monitoring of critical illness

When patients suffer from serious injury or infections in hospital (called sepsis), the flow of blood, to deliver oxygen around the body may be reduced.

Milestone n:0%

What does each milestone mean?

1 = Clinical need
2 = Idea
3 = Proof of concept
4 = Proof of feasibility
5 = Proof of value
6 = Initial clinical trials
7 = Validation of solution
8 = Approval and launch
9 = Clinical use
10 = Standard of care

Aim

To develop proof-of-concept that retinal blood flow monitoring using optical coherence tomography angiography (OCT-A may be a useful tool to monitor critical end organ perfusion in critically ill patients on the intensive care unit.

Lay Summary

When patients suffer from serious injury or infections in hospital (called sepsis), the flow of blood, to deliver oxygen around the body may be reduced. Doctors in hospital monitor blood pressure and other measures to assess how well oxygen is delivered to important parts of the body such as the brain and to guide treatment such as intravenous fluids. There are currently no good ways to directly measure blood flow to the brain when patients have sepsis. The blood flow in the back of the eye is closely linked to blood flow in the brain and can be assessed by taking a picture of the eye. Measuring blood flow in the eye may improve our ability to assess and treat patients with sepsis. We are therefore approaching people who are in hospital with infections or are planning to come into hospital for major surgery including thoracic or gastrointestinal operations at University Hospitals Birmingham (UHB). We will take pictures of the eye and test mental and visual functioning before the operation, 1-3 days after to look for problems with blood flow, and 3-6 months later to check that things have improved.

Background

When managing patients with critical illness including sepsis and hypovolaemic shock it is vital that perfusion of critical end organs including the heart and brain are monitored. Existing global perfusion measures include blood pressure and venous lactate. Local measures include urine output. Research measures include cerebral near-infrared spectroscopy, which may be useful for serial monitoring but is very variable between individuals and sublingual dark field microscopy which assesses local microcirculatory changes that may indirectly correlate with end-organ perfusion. The neuro-retina is part of the central nervous system and in healthy individuals, retinal perfusion mirrors cerebral perfusion and is subject to the same auto-regulatory mechanisms. Retinal perfusion is monitored non-invasively using OCT-A.

Pilot data obtained in the Queen Elizabeth Hospital suggests that OCT-A is a reliable method to assess retinal blood flow on ITU and changes in retinal blood flow may reflect systemic morbidity.

Method

We will recruit patients with scheduled major surgery at risk of sepsis and critical illness and assess retinal blood flow pre-operatively and post-operatively using OCTa alongside other measures of systemic and end-organ perfusion.