Capillary and Venous Lactate in Emergency Department Patients

Background:

Increase in lactate levels (hyperlactataemia) is common in critically ill patients and it is a sensitive marker in early identification of patients who are critically ill. Blood lactate is also a predictor of clinical outcomes. High level of lactate is associated with high mortality as well as increased morbidity. Capillary blood sample is easy to collect, less painful, and its measurement using handheld device which may allow more rapid determination of test results in ED. This rapid lactate measurement could aid early recognition of patients at high risk of mortality and morbidity. However, the accuracy of this rapid capillary lactate measurement using handheld devices has not been well studied in ED patients.

Objective:

To study the accuracy of capillary blood level measured by handheld lactate analyzers when compared with the reference methods e.g.venepuncture blood gas analyzer sample.

Study design:

This is a prospective observational study of patients presenting to ED of Prince of Wales Hospital (PWH). Patients aged 18 or above who are triage category 3 presenting to ED will be recruited. Capillary and venous blood samples will be collected. Venous lactate levels will be measured by blood gas analyzer (Siemens Automatic QC RAPID Systems RAPID Point@500) and two hand-held lactate analyzers (StatStrip Xpress Lactate Meter and Lactate Scout + ). Venous lactate levels measured by blood gas analyzer will be served as "reference method". Capillary lactate levels will be analyzed by handheld lactate analyzer. We are aimed to recruited 240 patients.

Outcomes:

The primary outcome is the accuracy of capillary blood level measured by handheld lactate analyzers when compared with the reference methods e.g. venepuncture blood gas analyzer sample. The secondary outcomes are: (1) compare the difference in values of venous lactate using blood gas analyzer and hand-held lactate analyzers, (2) compare values of capillary and venous lactate using hand-held lactate analyzers, (3) compare the reporting times of handheld and blood gas analyzer, and (4) Compare values of capillary lactate using between the two hand-held lactate analyzers.

Inclusion criteria

• Aged 18 years or above who are triage category 3 in emergency department
• Presenting to emergency department between 9am and 4pm, Monday to Friday

Exclusion criteria

• Aged below 18 years
• Pregnant