Can a Clinical Exam Establish a Low Alcohol Concentration After Trauma?

A reassuring clinical appearance cannot, by itself, establish a low alcohol concentration. A prospective study of 20 trauma patients found substantial disagreement between clinical observations and breath-based alcohol estimates. However, incomplete examinations and inconsistent counts in the paper limit the numerical conclusions that can be drawn.

What the patients and measurements represented

Kumar and colleagues enrolled 20 minimally injured trauma patients at one emergency department. Seventeen were men and three were women. All entered with a reported blood alcohol concentration above 80 mg/dL; the initial mean was 245 mg/dL, with a range of 162–370 mg/dL.

The paper does not adequately describe the initial laboratory assay and specimen matrix to justify treating these initial results as a documented whole-blood series. Subsequent testing used an Alco-Sensor FST breath instrument. Those serial readings were expressed as blood-equivalent mg/dL, rather than obtained through repeated blood collection.

Blood, serum and breath results should retain their actual identities in a case record. The site’s hospital serum alcohol analysis discusses the separate problem of interpreting a clinical serum result in a DUI investigation.

The examinations had important practical limits

Before repeated breath measurements, the investigators examined nystagmus, one-leg balance and heel-to-toe walking. Their balance task involved ten seconds on each leg, and the walking task used an approximately 15-foot room. These procedures should not be assumed to reproduce every element of a standardized roadside testing protocol.

Many patients could not complete the tasks. In the table’s above-80-mg/dL category, 13 of 20 were listed as unable to complete balance testing and 15 of 20 as unable to complete walking. An unperformed test is not a negative finding, and injury or other clinical conditions can restrict what can be observed.

The study supports caution about inferring alcohol concentration from appearance or a limited examination. It does not validate a new roadside classification rule or establish the diagnostic performance of a complete standardized field sobriety examination.

Why the paper’s pass-rate percentages need caution

The narrative reports nystagmus findings using a denominator of 16, while the corresponding table lists seven positive, six negative and seven unable-to-complete observations above 80 mg/dL. The reported balance and walking pass rates also do not align consistently with the table and the methods’ positive-test definitions.

These inconsistencies prevent a defensible calculation of precise sensitivity or specificity from the published summary alone. Quoting a single apparent pass rate would imply more certainty than the reporting supports.

The useful finding is narrower: some observations appeared reassuring despite elevated breath-based estimates, and a large fraction of examinations were incomplete. The study did not begin with a representative group spanning low and high concentrations, which further limits its use as a diagnostic validation study.

The observed decline was not a universal elimination rate

Serial breath-based estimates yielded apparent declines of 21.5–45.7 mg/dL per hour, with a mean of 28.5 mg/dL per hour. These values describe this small clinical sample and this measurement approach. They are not repeated direct blood measurements or a universal constant for reconstructing a driver’s earlier BAC.

The investigators did not find statistically significant relationships between the observed rate and age, sex or body mass index. With only 20 participants and just three women, those null findings cannot exclude meaningful differences in a larger population.

Concentration and functional ability remain separate questions

A result below a chosen concentration threshold does not establish full functional recovery, medical readiness for discharge or fitness to drive. Conversely, an ordinary-looking examination does not quantify alcohol concentration.

For a DUI assessment, the specimen or instrument result, sampling time, actual observed behavior and feasibility of each examination should be documented separately. Any estimate about an earlier time needs additional assumptions. The site’s analysis of laboratory tests and driving prediction explains why detecting an alcohol effect and predicting driving performance require different evidence.

Primary source

Kumar A and colleagues. The Clinical Evaluation of Alcohol Intoxication Is Inaccurate in Trauma Patients. Cureus. 2018;10(2):e2190. https://doi.org/10.7759/cureus.2190.