Impairment of pulmonary functions
Ramar Sabapathi Vinayagam in Integrated Evaluation of Disability, 2019
Pulmonary function tests namely forced expiratory volume in one second (FEV1), FVC, FEV1/FVC ratio, and Total Lung Capacity (TLC) interpret impairment of lung function. FEV1/FVC ratio ≥0.7 and FVC >80% of predicted are normal spirometry values. FEV1/FVC ratio <0.7 indicate airway obstruction. FEV1/FVC ratio ≥0.7 and FVC <80% of predicted refer to the restrictive pattern. FEV1/FVC ratio <0.7 and FVC <80% of predicted indicate mixed pattern (2). In general, FEV1 grades the degree of impairment of pulmonary function (3). Post-bronchodilator FEV1 assesses airway responsiveness, and a FEV1 less than 80% of predicted indicates a limitation of airflow (4). The ratio of post-bronchodilator FEV1/FVC to forced vital capacity less than 0.70 indicates airflow limitation in obstructive pulmonary diseases. A decrease in TLC below the fifth percentile and normal FEV1/VC ratio represent restrictive lung diseases. An increase in arterial partial pressure of carbon dioxide (PaCO2), end-tidal PCO2 or an elevation of transcutaneous PCO2 more than 55 mm of Hg for ≥10 minutes; or an elevation of PaCO2 or end-tidal PCO2 or transcutaneous PCO2 by 10 mm above 50 mm of Hg for ≥10 minutes during sleep refers to hypercapnic failure.
Anaesthetic Management of Early-Onset Scoliosis
Alaaeldin (Alaa) Azmi Ahmad, Aakash Agarwal in Early-Onset Scoliosis, 2021
Respiratory System: The deformity of the chest wall leads to a restrictive kind of lung disease due to limitation of the movement of the rib cage upon inspiration and compression of the lung tissue; however mixed or obstructive lung disease may be present in 46% of the patients [10,11]. Altered respiratory mechanics and reduced lung volume leads to restrictive lung disease, and airway narrowing leads to obstructive lung diseases in some cases [12]. Total lung capacity (TLC) is reduced whereas residual volume (RV) usually remains within normal limit, hence RV/TLC ratio is increased [13]. The forced vital capacity (FVC) and forced expiratory volume in the first-second (FEV1) both are reduced so that the ratio of FEV1 /FVC almost remains normal [14]. The reduction in the vital capacity represents the inability to cough and clear lung secretions effectively, leading to frequent lower respiratory tract infections [15]. The limitation of expansion of lung tissue leads to a decrease in respiratory compliance and, when combined with stretching of the intercostal muscles, leads to increase in work of breathing, resulting in decreased tidal volume and increased respiratory rate. The inspiratory capacity is maximally affected, while the functional residual capacity (FRC) is not that severely affected. In severe cases, as the curve progresses, an increase in residual volume may develop due to inadequate expiration as a result of muscle dysfunction.
Positional and Restraint Asphyxia
Darrell L. Ross, Gary M. Vilke in Guidelines for Investigating Officer-Involved Shootings, Arrest-Related Deaths, and Deaths in Custody, 2018
Prior to the Price case testimony, Dr. Neuman and a team of researchers performed a more comprehensive research study, investigating the physiology of prone restraint that was funded by the County of San Diego (Chan et al., 1997). In this study, the researchers measured ventilatory parameters, including forced vital capacity (FVC)—the amount of air an individual could exhale in a single breath—as well as forced expiratory volume in one second (FEV1)—the amount of air an individual could exhale rapidly in the first second of exhalation. These measures indicate the overall status of ventilatory function in an individual and are often used to assess patients with various lung conditions, including asthma. Interestingly, the researchers documented drops in these measures in the supine, prone, and prone maximal restraint positions when compared with sitting, suggesting some decrease in ventilation based on body position (including lying on the back). However, these measures have a range of normal that varies based on an individual's size and ethnicity, and in no cases were the parameters considered abnormal. On a physiologic level, this is consistent with prior work in respiratory physiology. The normal human body has excess ventilatory capacity such that lung function must be reduced significantly (i.e., less than 50 percent) to have an impact on oxygenation (Chan et al., 1997).
Pulmonary hypofunction due to calcium carbonate nanomaterial exposure in occupational workers: a cross-sectional study
Published in Nanotoxicology, 2018
Guoliang Li, Lihong Liang, Jingchao Yang, Lihai Zeng, Zhiwei Xie, Yizhou Zhong, Xiaolin Ruan, Ming Dong, Zhanhong Yang, Guanchao Lai, Weixin Huang, Aichu Yang, Jiabing Chen, Banghua Wu, Huaming Xu, Dezhi Meng, Shijie Hu, Lihua Xia, Xingfen Yang, Laiyu Li, Sahoko Ichihara, Gaku Ichihara, Hanlin Huang, Zhenlie Huang
Pulmonary function tests (PFTs) were measured by Spirolab III diagnostic spirometry (MIR, Rome, Italy) to determine lung function in terms of the amount (volume) and/or speed (flow) of air that could be both inhaled and exhaled. Spirometry parameters included forced vital capacity (FVC) – the total amount of air forcibly blown out after full inspiration, measured in liters. Vital capacity (VC) is the maximum amount of air that can be exhaled after a maximum inhalation. Forced expiratory volume in 1 s (FEV1) is the amount of air forcibly blown out in one second, measured in liters/second. Maximum voluntary ventilation (MVV) is the maximum voluntary ventilation over a period of 60 s. Peak expiratory flow (PEF) is an individual’s maximum speed of expiration. Forced expiratory flow (FEF) is the flow (or speed) of air coming out of the lungs during the middle portion of a forced expiration.
A pilot study of differential gene expressions in patients with cough variant asthma and classic bronchial asthma
Published in Journal of Asthma, 2022
Guanghong Zhou, Qingcui Zeng, Wei Wei, Hong Teng, Chuntao Liu, Zhongwei Zhou, Binmiao Liang, Huaicong Long
The characteristics of the individuals in each group are summarized in Table 2. Age, body mass index (BMI), FEV1/FVC (FEV1:Forced expiratory volume in one second; FVC: forced vital capacity) and FEV1%/Pred were not significantly different among the HC, CA and CVA groups. Fraction of exhaled nitric oxide (FeNO) between CA and CVA groups was not significantly different (20(16.5), 24(26.5), p > 0.05); all individuals from the CA and CVA groups had a history of allergic rhinitis. The course of disease between the CA and CVA groups was significantly different (8 ± 11.38 years vs. 1.8 ± 1.6 years, P < 0.01). All individuals had normal white blood cell counts; one patient with asthma had an elevated percentage of eosinophils in blood (≥5%); one patient with classical asthma had an elevated IgE level (≥100 IU/mL); four and three individuals from the CA and CVA groups, respectively, were using inhaled corticosteroids; and no individual was using oral corticosteroids.
Challenges in uncontrolled asthma in pediatrics: important considerations for the clinician
Published in Expert Review of Clinical Immunology, 2022
Beatrice Andrenacci, Giuliana Ferrante, Giulia Roberto, Giorgio Piacentini, Stefania La Grutta, Gian Luigi Marseglia, Amelia Licari
Spirometry is a noninvasive, informative tool in asthma diagnosis. The hallmark of asthma is variable airflow obstruction and bronchial hyperreactivity. In obstructive airway disease, the forced expiratory volume in the 1st second/forced vital capacity ratio (FEV1/FVC) is typically reduced. However, FEV1/FVC should not be considered alone, because it cannot convey whether one or both components are within normal limits or not. When spirometry shows reduced values, a bronchodilator test should be performed to assess reversibility; an increase in FEV1 of ≥12% is considered significant according to ERS/ ATS standards [105]. However, in children, the sensitivity and specificity of this cutoff are under debate [91]. However, it should be pointed out that GINA documents still recommend symptom-based asthma management versus spirometry-based management [14].
Related Knowledge Centers
- Asthma
- Exhalation
- Pulmonary Fibrosis
- Cystic Fibrosis
- Lung
- Inhalation
- Chronic Obstructive Pulmonary Disease
- Spirometer
- Pulmonary Function Testing
- Public Health Surveillance