A breathalyzer test can rapidly and accurately screen for Covid-19 in critically ill patients, according to results from a preliminary study published in the journal PLoS One.¹

The study included 46 patients on mechanical ventilation admitted to Intensive Care Units (ICUs); 23 had active Covid-19 respiratory infection, while the remaining 23 did not have Covid-19 and acted as controls. Exhaled air samples were collected on days 1, 3, 7 and 10 in 1-liter breath bags connected to the exhalation port of the ventilator over which a HEPA filter was placed to minimize potential aerosolization of virus. All samples were analysed in BSL3 level lab within 4 hours of collection using a new breathalyzer technology, an electronic device which “utilizes a single selective, resistive chemosensor made of a catalytically active, semiconducting material, targeting NO and ammonia molecules in breath. The use of a single sensor allows for rapid analysis of data and diagnostic results. This then allows the device/tester to detect the distinct signature (breath print) of COVID-19, non-invasively, in exhaled breath, within 15 seconds”. 

Analysis of samples from critically ill Covid-19 patients identified a “breath print” that was characteristic to Covid-19 based on the amount of oxygen, ammonia, and nitric oxide. It had three peaks resembling the small Greek letter omega. Hence, it was termed the “omega” pattern. Significantly, this pattern was detected within 15 seconds. Two other patterns were also identified – NO pattern and NH3/O2 pattern.

Out of the 16 patients who tested positive for Covid-19 on the first day of the study, 14 (88%) showed the omega pattern compared to four in the control group, while 19 patients in the control group had a non-Omega pattern. The test was found to have a specificity of 83%, a positive predictive value of 78% and a negative predictive value of 90%. Its accuracy was 85%.

Currently, RTPCR is the confirmatory test for Covid-19. But it requires trained healthcare workers to collect the samples and to conduct the test. PCR can be negative in the early stage of the infection yielding a false-negative result. The waiting time for results usually ranges between 24 hours and 48 hours. However, during the deadly second wave, the waiting time was much longer when the labs were overwhelmed with the huge number of tests they had to carry out every day.

This study is the first to demonstrate diagnosis of Covid-19 from a distinct “breath print” obtained with a nanosensor breathalyzer system. The non-invasive nature of the test and the quickness of results obtained within seconds, seem particularly appealing. It was able to identify the “omega” pattern in patients with early Covid-19 infection, within 72 hours of onset of respiratory failure. Hence, this test can be potentially used to quickly screen both asymptomatic and symptomatic persons with respiratory infections to diagnose Covid-19.

Reference

1. Exline MC, et al. Exhaled nitric oxide detection for diagnosis of COVID-19 in critically ill patients. PLOS One 2021; DOI: 10.1371/journal.pone.0257644.