Breathe easy: A bedside test for sepsis

ICU breath test

Cheminformatics work on Ion Mobility Spectrometry (IMS) demonstrates that, in an animal model at least, the exhaled breath can be used as an accurate, fast and simple point-of-care tool for the diagnosis and monitoring of sepsis.

Ana Guamán, Alba Carreras, Daniel Calvo, Idoya Agudo, Daniel Navajas, Antonio Pardo, Santiago Marco and Ramon Farré of the Institute for Bioengineering of Catalonia (IBEC), in Baldiri i Rexach, Spain, explain that sepsis is one of the main causes of death in adult intensive care units (ICU). However, there is no simple method for monitoring the condition in a timely manner. Moreover, the current techniques usually involve taking a sample and sending it off to a laboratory for testing, which adds to the delays and worries for the patient and their carers and also increases the risk of inadvertent mixups in sample handling.

A simple bedside test for sepsis that is quick and non-invasive could improve patient outcomes considerably by accelerating diagnosis and allowing appropriate treatment to be given much sooner when needed.

Sepsis, from the Greek word for putrefaction and decay usually involves whole-body inflammation, a systemic inflammatory response, due to an infection. The response can occur in the blood, urine, lungs, skin, or elsewhere and cause organ failure and ultimately death. Colloquially, sepsis of the blood is often referred to as blood poisoning, septicaemia.

The researchers have developed a model diagnostic system tested on twenty Sprague-Dawley rats. Half the rats were injected with lipopolysaccharide from the pathogenic microbe Escherichia coli and the other ten rats were injected with regular saline. The team anaesthetized the animals after one day and then collected the animals' exhaled breath. IMS and SPME-gas chromatography/mass spectrometry (SPME-GC/MS) were then used to analyse the chemical components of the breath. They applied multivariate data processing techniques to the results.

" The SPME-GC/MS dataset processing showed 92% accuracy in the discrimination between the two groups, with a confidence interval of between 90.9% and 92.9%," the team says in a recent issue of the J Chromatogr B Analyt Technol Biomed Life Sci. They add that, "Percentages for sensitivity and specificity were 98% (97.5-98.5%) and 85% (84.6-87.6%), respectively. The IMS database processing generated an accuracy of 99.8% (99.7-99.9%), a specificity of 99.6% (99.5-99.7%) and a sensitivity of 99.9% (99.8-100%)."

IMS offers short analysis times and precise results as well as precluding the need for any sample or biopsy to be sent to a lab for assessment. Simple, continuous bedside monitoring of a patient's breath to detect the early signs of sepsis based on a change in chemical composition of the breath should now be possible.