Use of Area under the Expiratory Flow-volume Curve and Rectangular Area Ratio in Detecting Ventilatory Impairments in Spirometry: A Pilot Study | ||||
| Bulletin of Egyptian Society for Physiological Sciences | ||||
| Article 9, Volume 41, Issue 2, April 2021, Page 258-269 PDF (514.97 K) | ||||
| Document Type: Original Article | ||||
| DOI: 10.21608/besps.2020.35867.1068 | ||||
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| Authors | ||||
Ibrahim El-Akkary1; Eman Y. Khairy2; Ola A. Salama2; Ghada Abu-Sheasha3; Nancy Diaa Moussa  4
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| 1Department of Human Physiology, Medical Research Institute, Alexandria University, Alexandria, Egypt | ||||
| 2Department of Human Physiology, Medical Research Institute, Alexandria University, Egypt. | ||||
| 3Department of Biomedical informatics and Medical Statistics, Medical Research Institute, Alexandria University, Egypt | ||||
| 4Medical Research Institute, Alexandria University | ||||
| Abstract | ||||
| Purpose: This study aimed at demonstrating the reliability of surface area under the maximum expiratory flow volume curve (Aex) and rectangular area ratio (RAR) to define the type of ventilatory impairment and assessing potential clinical value of Aex ratio (measured / predicted Aex) to indicate the severity of ventilatory obstruction. Methods: Spirometric data of 75 subjects were analyzed by qualified pulmonologists to distinguish between different spirometric patterns representing expert decision. Computerized graphic analysis methodology was used, Aex was used to calculate other parameters (area of concavity and RAR) and an algorithm for diagnosis was proposed. For validation of the proposed grading and cutoff values, we compared them with expert decision using classification and regression trees (CART). Results: According to calculated parameters, obstructive pattern is realized if area of concavity (Au) has positive value and RAR is less than 0.5. While convexity/linearity is indicated if RAR ≥ 0.5 and Au has negative value or equal zero, indicating normal or restrictive pattern. Aex ratio was selected as second-best predictor of restriction at a cut-off value of 49%. Furthermore, the diagnostic performance of Aex ratio in predicting moderate-to-severe obstructive lung disease was excellent. Conclusion: The proposed computerized technique succeeded using RAR and Aex in differentiating between restriction, obstruction and normal patterns. Additionally, Aex ratio may be a valid parameter to grade the severity of obstruction. | ||||
| Keywords | ||||
| Spirometry; flow-volume curve; rectangular area ratio (RAR); ventilatory impairment; Aex ratio | ||||
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