GERD-related microaspiration as a contaminant in breath alcohol testing: Case reports

Abstract

Forensic breath alcohol testing depends on contamination-free breath sampling. This case study describes two subjects with a history of gastro-oesophageal reflux disease (GERD) and other aerodigestive symptoms who exhibited repeated coughing near the time of breath alcohol testing. Breath alcohol expirograms demonstrated negative slopes consistent with mouth alcohol contamination. The observations raise the possibility that microaspiration may represent a source of such contamination, and the cases are presented as hypothesis-generating. Further research is needed to evaluate GERD-related microaspiration in the context of breath alcohol testing.

Introduction

Breath alcohol testing is a cornerstone of impaired driving investigations. It is relied on by courts and law enforcement to measure a subject’s breath alcohol concentration (BrAC). One of the limitations of breath alcohol testing, however, is the contamination of the sample with alcohol from recent food or drink, or from burping, belching or vomiting alcohol from the stomach into the oral cavity. ¹

To mitigate this risk, breath testing protocols require a continuous pre-test observation period, typically 15–20 minutes, during which the subject must not eat, drink, smoke, vomit, regurgitate or burp. ¹ In addition, some modern breath alcohol analysers employ BrAC slope detection algorithms and duplicate sampling to try to detect mouth alcohol contamination.

Despite these safeguards, undetected mouth alcohol contamination continues to be reported. ² One underexplored mechanism of mouth alcohol contamination is microaspiration of gastric contents, particularly in individuals with gastro-oesophageal reflux disease (GERD) and chronic cough. Microaspiration refers to the inhalation of small amounts of gastric reflux into the larynx, trachea or airways. ³ GERD is associated with chronic cough, and may be both a consequence of reflux-related microaspiration and a contributing factor to reflux.^4,5

Case report 1

A 163-pound, 60-year-old male was stopped by a traffic officer in Minnesota while driving. The subject was arrested under suspicion of driving while impaired. During the traffic investigation, the subject admitted to drinking two beers before driving. Medical records spanning more than a decade documented persistent aerodigestive issues. Medical records showed a history of dysphagia, globus sensation, chronic throat clearing, GERD, chronic cough, burning mouth syndrome and a complaint of a constant acid taste in the mouth. An endoscopic exam of his larynx revealed a small mucocele on the left aryepiglottic fold, and his vocal cords showed atrophic mucosa. The subject had been prescribed omeprazole (Prilosec) 40 mg daily.

The subject was administered two breath alcohol tests on the DataMaster DMT (DMT) (Intoximeters, Inc., St. Louis, MO). The testing sequence required duplicate samples taken approximately 3-minutes apart to agree within 0.02 g/210 L of each other.

During the pre-test observation period and testing sequences, the subject exhibited persistent coughing and throat clearing. The video recorded over 37 distinct coughing or throat-clearing events during the observation period, including a coughing fit within seconds of breath sampling.

The first breath test resulted in a reported outcome of ‘Deficient’ due to failing to achieve a level BrAC slope. Instead, the breath expirogram showed a negative slope during the last portion of the breath. The officer immediately proceeded to another test sequence.

The second breath test produced a reported BrAC value of 0.14 g/210 L. Inspection of the expirograms, however, revealed a negative-going BrAC slope consistent with mouth alcohol contamination seen in Figure 1.

Figure 1.

Case 1 BrAC expirogram from the second breath alcohol test showing a negative slope consistent with mouth alcohol contamination.

Case report 2

A 225-pound, 64-year-old male was stopped by a traffic officer in Minnesota while driving and placed under arrest for suspicion of driving while impaired. The subject admitted to drinking two beers before driving. The subject had been diagnosed with chronic GERD without oesophagitis and had been prescribed omeprazole (Prilosec) 20 mg daily.

The subject was administered one breath alcohol test on the DataMaster DMT. The testing sequence required duplicate samples taken approximately 3-minutes apart to agree within 0.02 g/210 L of each other. Video of the pre-test observation period showed the subject coughed three times: twice before the first sample and once before the second sample. The reported value for the test was 0.11 g/210 L. The expirogram revealed a negative-going BrAC slope consistent with mouth alcohol contamination, shown in Figure 2.

Figure 2.

Case 2 BrAC expirogram from the breath alcohol test showing a negative slope consistent with mouth alcohol contamination.

Discussion

Microaspiration is a recognised phenomenon in patients with GERD, particularly those with chronic cough.^4,6,7 Small volumes of gastric contents may reach the larynx and proximal airways without overt regurgitation. While such events may be clinically silent, ⁸ they can provoke coughing and throat clearing as protective reflexes.^9,10

In the context of breath alcohol testing, there is a possibility that microaspirated gastric contents containing ethanol could contaminate the airways and oral cavity, as seen in Figure 3.

Figure 3.

Illustration of gastro-oesophageal reflux–related microaspiration as a potential mechanism for breath alcohol contamination.

Conclusion

This report describes two subjects with GERD and coughing who exhibited negative-sloped breath alcohol expirograms. The convergence of medical history, observed coughing and negative-sloped expirograms is consistent with the possibility that microaspiration of gastric contents may have contributed to contamination of the breath samples.

These observations are limited by the absence of direct measurement of microaspiration or ethanol within the upper airway. Alternative explanations, including other sources of residual mouth alcohol contamination, cannot be excluded. The magnitude and duration of the potential effect of microaspiration on reported breath alcohol concentrations remain unknown. Forensic practitioners should remain attentive to individuals with medical histories of aerodigestive disorders and examine the video as part of a thorough case review.

Supplemental Material

sj-xlsx-1-mlj-10.1177_00258172261442706 – Supplemental material for GERD-related microaspiration as a contaminant in breath alcohol testing: Case reports

Supplemental material, sj-xlsx-1-mlj-10.1177_00258172261442706 for GERD-related microaspiration as a contaminant in breath alcohol testing: Case reports by Aaron Olson in Medico-Legal Journal