In Reply: Role of spirometry in fixed upper airway obstruction

In Reply: We appreciate the careful reading of our article¹ and the identification of the typo in Table 2. Indeed, the correct ratio is FEV₁/FVC (forced expiratory volume in 1 second/forced vital capacity) and not the inverse.

Dr. Talwar and colleagues clearly highlight some of the challenges in making the diagnosis of laryngeal stenosis. The clinician must be aware that both the quantitative and qualitative data derived from pulmonary function testing have limitations and always require clinical correlation. The literature discusses the use of various ratios from pulmonary function testing results, including the expiratory disproportion index, maximum voluntary ventilation/FEV₁ ratio, and the ratio of forced inspiratory flow at 25% to 75% of FVC to forced expiratory flow at 25% to 75% of FVC (FIF 25%–75% FVC/FEF 25%–75% FVC), to assist in the diagnosis of upper airway obstruction. Unfortunately, data on sensitivity and specificity are limited.

The gold standard in making this diagnosis remains laryngoscopy. Nevertheless, the first step is to identify stridor as a clinical finding distinct from the much more common wheezing due to asthma.

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