key: cord-281113-t450ccnq authors: Mattar, Rejane title: Breath tests for gastrointestinal diseases - will it be safe to conduct breath tests after the COVID-19 pandemic? date: 2020-06-16 journal: Clinics (Sao Paulo) DOI: 10.6061/clinics/2020/e2092 sha: doc_id: 281113 cord_uid: t450ccnq nan intolerance, a genetic test is a safer choice than the lactose breath test (8) . The instruments to measure H 2 , generated by bacterial fermentation of carbohydrates, in end-alveolar breath samples, may be stationary (CM2 microlyzer, Breath tracker analyzer) or portable (Gastrolyzer, Easy H 2 ). When using stationary equipment, the patient blows into a plastic device, consisting of a mouthpiece and T valve attached to a plastic bag. The breath is aspirated into a 30 mL syringe attached to the T valve (8) . When using portable equipment, the patient inspires the air deeply, holds the air inside the lung for 15 seconds, and then blows all the air into a mouthpiece attached to the equipment. The patient forces expiration that generates respiratory droplets and aerosols. Viral RNA was detected in respiratory droplets and aerosols from coronavirus-, influenza virus-, and rhinovirus-infected patients (9) . The patient blows the H 2 baseline collection and several times after swallowing a carbohydrate substrate. The exam lasts 1 hour and 20 minutes for SIBO and three hours for lactose intolerance. The test carries risks of contamination to the healthcare worker collecting the breath samples and to the patients, as the ultrafine aerosol droplets may also carry SARS-CoV-2 and remain airborne for long periods, and could be inhaled (5) . For the 13 C-urea breath test for H. pylori infection diagnosis, the patient blows into a plastic mouthpiece attached to an aluminized bag. Patients inspire the air and blow with strain until the bag is completely full of air. Sometimes it stimulates cough. Breath samples are collected before and after ingesting a 13 C-urea capsule (3) . Although the test lasts 20 minutes, it carries the risk of contamination by SARS-CoV-2 in the aerosol droplets generated by the exhaled air (5) . One possibility to overcome the risks of contamination is a pre-procedural mouth rinse, including chlorhexidine, cetylpyridinium chloride, and essential oils that decreases the proportion of microorganisms in oral aerosols, and leads to a mean reduction of 68.4% colony-forming units in dental aerosols. The impact on coronavirus is uncertain; however, it is efficient against human immunodeficiency, herpes simplex, and hepatitis B viruses (10) . Wearing protective glasses, face shields, surgical masks, or particulate respirator Healthcertified N95, or equivalent (10), may protect the healthcare worker, but not the patient that has to blow inside a room with oral aerosols, generated by previous exams. Patient selection should be done based on a negative swab for DOI: 10.6061/clinics/2020/e2092 Copyright & 2020 CLINICS -This is an Open Access article distributed under the terms of the Creative Commons License (http://creativecommons.org/licenses/by/ 4.0/) which permits unrestricted use, distribution, and reproduction in any medium or format, provided the original work is properly cited. No potential conflict of interest was reported. SARS-CoV-2 by real-time reverse transcription-PCR; however, the nasopharyngeal swab specimen has to be properly collected by inserting deeply into the nasal cavity, or it can produce a false negative (11) . Other analytical assays for SARS-CoV-2 diagnosis include antigen detection by lateral flow assays that are fast and low cost; nonetheless, these tests lack good sensitivity early in the infection stage (11) . Serology detection, an indirect method, is reliable to indicate past infection than active ones (11) . It would be better to wait for a vaccine before resuming breath tests again, but it is unknown how long that will take. Breath tests for gastrointestinal disease: the real deal or just a lot of hot air? Breath Analysis Using eNose and Ion Mobility Technology to Diagnose Inflammatory Bowel Disease -A Pilot Study Low dose capsule based 13 C-urea breath test compared with the conventional 13 C-urea breath test and invasive tests Recent advances in the detection of respiratory virus infection in humans Breath diagnostics in the era of SARS-CoV-2 -in clinical and research arena Epidemiological, clinical characteristics of cases of SARS-CoV-2 infection with abnormal imaging findings Digestive Symptoms in COVID-19 Patients With Mild Disease Severity: Clinical Presentation, Stool Viral RNA Testing, and Outcomes Single nucleotide polymorphism C/T(-13910), located upstream of the lactase gene, associated with adult-type hypolactasia: validation for clinical practice Respiratory virus shedding in exhaled breath and efficacy of face masks What dentists need to know about COVID-19 Laboratory Diagnosis of COVID-19: Current Issues and Challenges