Diagnostic accuracy of the Voluntary Breath-Hold Test to discriminate normal vs. abnormal spirometry: a two-gate study

INTRODUCTION: The Voluntary Breath-Hold Test (VBHT) is a simple, bedside, and rapid assessment that measures the duration of voluntary apnea. It has shown potential for clinical use, including as a triage tool prior to spirometry in primary care. However, its diagnostic accuracy in detecting abnormal pulmonary function before non-thoracic surgeries has not been established. This study aimed to determine the correlation between VBHT results, Maximal Voluntary Apnea Inspiratory Time (MVAIT) and Maximal Voluntary Apnea Expiratory Time (MVAET), and spirometry, the reference test for assessing pulmonary function. METHODS: This diagnostic-accuracy study included adults with normal spirometry and those with obstructive or restrictive ventilatory defects. Participants were divided into normal and abnormal spirometry groups. Maximal Voluntary Apnea Inspiratory Time (MVAIT) and Expiratory Time (MVAET) were evaluated using Receiver Operating Characteristic (ROC) curve analysis to assess their accuracy in distinguishing between normal and abnormal spirometry patterns. RESULTS: The study included 293 participants. MVAIT and MVAET were significantly lower for the abnormal (median: 29.32 s; 95% Confidence Interval [95% CI]: 25.99‒32.35 s and median: 20.40 s; 95% CI: 18.66‒22.88 s) than for the normal (median: 47.55 s; 95% CI: 43.93‒51.87 s and median: 28.53 s; 95% CI: 26.74‒30.63 s) group. For the prediction of normal spirometry, MVAIT ≥ 45.49 s and MVAET ≥ 32.86 s had sensitivity and specificity of (90.43%, 55.06%) and (90.43%, 33.71%), respectively. CONCLUSION: VBHT is a bedside, low-cost, and safe method that shows moderate-to-good discriminative ability for identifying abnormal spirometry results. As an innovative adaptation of a long-known physiological maneuver, VBHT may serve as a rapid preliminary triage (rule-out) tool prior to formal spirometry, pending external validation in preoperative populations. CTRI REGISTER NUMBER - REBEC (REGISTRO BRASILEIRO DE ENSAIOS CLíNICOS): RBR-8hknmn.