Comparison of Forced Oscillometric Technique and Spirometry in Stable Asthmatic Patients in Central India: A Cross-sectional Study

Abstract

Introduction: Asthma is an airway disease, the diagnosis of this disease still continues to be a clinical based. Although, there are several tests that can be useful for asthma, but no one can be considered as a standard test and search for better test is still on. Spirometry being the most commonly used test but it involves effortful manoeuvre, whereas Forced Oscillometric Technique (FOT) is a lesser studied techniuque with no special manoeuvre. Aim: To compare between spirometry and FOT in adults asthmatic patients for assessing the utility of FOT. Materials and Methods: The present cross-sectional study was conducted at School of Excellence in Pulmonary medicine at Netaji Subhash Chandra Bose Medical College, Jabalpur, Madhya Pradesh, India, in 50 clinically diagnosed bronchial asthma patients between August 2020 to July 2021. These patients were sequentially assessed with spirometry and FOT. The patients were categorised into clinical severity and airflow limitation severity on spirometry. The baseline parameters Forced Expiratory Volume (FEV)1 , Forced Vital Capacity (FVC), FEV1 /FVC, Forced Expiratory Flow (FEF) 25-75, R5, R 20 R5- 20,X5, Z 5 were obtained by both the tests were analysed and compared for detecting the utility of FOT by using BlueSky statistical software- 10.0.0-Beta2 version. Results: Among 50 enrolled patients (21 males and 29 females) with asthma, 42 (84%) were mild and 8 (16%) were moderate. The mean age of patients is 27.5±6.6 years. The total airway resistance (R5) was the most consistent FOT parameter that was statistically different in asthma severity groups as well as in spriometry severity group (p-value=0.01). Peripheral airway resistance (R5-R20), and impedance Z5 were other variables that were significant between airflow limitation groups with a p-value of 0.01. A significant correlation was found between spirometry and FOT parameters including FEV1 , FVC, FEV1 /FVC with R5 (r>-0.5 at p-value of -0.5 at p-value of 0.05. Conclusion: FOT parameters correlated with spirometric indices therefore this technique may be a useful measure in asthma diagnosis. Further studies are needed to derive cut-off values of FOT parameters.

Keywords

• airway obstruction
• airway resistance
• forced expiratory volume
• lung volume
• lung capacity
• reactance