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Physiologic Changes
Published in Vincenzo Berghella, Obstetric Evidence Based Guidelines, 2022
Uterine enlargement and abdominal distension result in a 4- to 5-cm cephalad displacement of the diaphragm and a 5- to 7-cm increase in thoracic circumference. This results in a decrease in expiratory reserve volume, residual volume, and functional residual capacity. There is a compensatory increase in inspiratory capacity, while total lung capacity and vital capacity do not change [14]. Chest wall compliance is increased, but inspiratory muscle strength is preserved with an overall increase in the oxygen cost of breathing [14]. However, it is important to recognize that there is no significant change in the parameters of forced vital capacity, peak expiratory flow rate (PEFR), or forced expiratory volume in 1 second (FEV1) during pregnancy.
Pulmonary Function Testing
Published in Pudupakkam K Vedanthan, Harold S Nelson, Shripad N Agashe, PA Mahesh, Rohit Katial, Textbook of Allergy for the Clinician, 2021
Ekta Kakkar, Flavia CL Hoyte, Devasahayam J Christopher, Rohit K Katial
VC is the maximum amount of air a person can expire from the lungs after a maximum inhalation. It is also the sum of the tidal volume and inspiratory and expiratory reserve volumes (i.e., VC = TV + IRV + ERV). VC is used in neuromuscular diseases like Guillain-Barre Syndrome and myasthenia gravis to determine the severity of respiratory muscle involvement. A normal, healthy adult has a vital capacity between 3 and 5 liters (David et al. 2019). VC is decreased in restrictive diseases. In obstructive lung disease, VC can be normal or slightly decreased (David et al. 2019).
Anaesthetic Management of Early-Onset Scoliosis
Published in Alaaeldin (Alaa) Azmi Ahmad, Aakash Agarwal, Early-Onset Scoliosis, 2021
Damarla Haritha, Souvik Maitra
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.
Effect of muscle distribution on lung function in young adults
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Wenbo Shu, Mengchi Chen, Zhengyi Xie, Liqian Huang, Binbin Huang, Peng Liu
A decreased skeletal muscle mass in patients with COPD is related to a decreased lung function (Jones et al. 2015). Some scholars believe that a common pathway exists between decreased lung function and low skeletal muscle mass (Jones et al. 2015). Early reports about the decline in skeletal muscle mass and lung function were aimed at elderly people over 65 years old (Moon et al. 2015) or people with poor health (Jones et al. 2015; Panagiotou et al. 2016; Shi et al. 2019). The skeletal muscle mass is affected by sex, age, various metabolic factors, physical conditions, and health-related behaviors (Moorthi and Avin 2017; Ponziani and Gasbarrini 2018), and these factors may have certain effects on lung function. However, some studies have found that healthy adult skeletal muscle mass is independently related to forced expiratory volume within 1 second (FEV1), forced VC (FVC), and maximum respiratory flow (PEF). This relationship still exists after adjusting for confounding factors (Bahat et al. 2014). A study in healthy adults explored the relationship between skeletal muscle mass and lung function, and found that the decrease in skeletal muscle mass was independently related to forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1) (Park et al. 2018). A Japanese study explored the relationship between body composition and lung function of community residents. The results found that the skeletal muscle index was correlated with the FEV1/FVC ratio in young women and old men (Kawabata et al. 2020).
Pulmonary functions and associated risk factors among school teachers in a selected Nigerian population
Published in International Journal of Occupational Safety and Ergonomics, 2022
Chidiebele Petronilla Ojukwu, Precious Chinecherem Ogualaji, Stephen Sunday Ede, Rita Nkechi Ativie, Chigozie Okwudili Obaseki, Adaora Justina Okemuo, Franklin Onyedinma Irem
The PFTs were then performed as follows. Each test was performed three times. To assess the FVC, the participants were asked to inhale maximally and then exhale forcefully for at least 6 s. The value of the FVC is read from the spirometer. To assess the vital capacity (VC), the participants were asked to inhale maximally and exhale maximally whether forcefully or not. In healthy subjects, the FVC is equal to the VC. To assess the FEV1, the participants were asked to inhale maximally and exhale forcefully for a maximum of 6 s. The volume of air exhaled after 1 s is read from the spirometer. The FEV1/FVC ratio is calculated from the ratio of the FEV1 to the FVC. This allows the identification of obstructive or restrictive respiratory defects. The maximal flow rate of the subjects during expiration (PEFR) and maximal flow rates between 25 and 75% of the vital capacity (FEF25–75%) were also measured.
Correlations between measures of ALS respiratory function: is there an alternative to FVC?
Published in Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration, 2021
Deirdre Murray, James Rooney, Amar Al-Chalabi, Tommy Bunte, Theresa Chiwera, Mutahhara Choudhury, Adriano Chio, Lauren Fenton, Jennifer Fortune, Lindsay Maidment, Umberto Manera, Chris Mcdermott, Dara Meldrum, Myrte Meyjes, Rachel Tattersall, Maria Claudia Torrieri, Philip Van Damme, Elien Vanderlinden, Claire Wood, Leonard H. Van Den Berg, Orla Hardiman
Alternative respiratory measurements such as sniff nasal inspiratory pressure (SNIP) and overnight pulse oximetry provide supplementary information to forced and slow vital capacity in clinical practice (6,7). Forced and slow vital capacity measure the maximum volume of air that can be exhaled from the lungs during a complete expiration from a position of full inspiration. Vital capacity is considered a global measure of respiratory function, involving multiple muscle groups as well as passive recoil of a distended chest. In comparison, SNIP is a measure of the pressure generated during a maximal inhalation through the nostril, considered valuable in detection of early diaphragmatic weakness, which may not be apparent from FVC / SVC scores alone (7,15,16). Additionally, it is suitable for patients with bulbar weakness who cannot achieve a seal on an FVC mouthpiece (15,17) and has shown a linear pattern of decline in the first 24–36 months after disease onset (18). Presently, in clinical practice, patient management is guided by these complementary respiratory measures, as well as subjective symptoms (6,9). Although the tests measure different aspects of respiratory dysfunction, their respective patterns of decline over time may show similarities in people with ALS. The potential for SNIP to provide an alternative, lower-risk method of in-clinic respiratory testing during the COVID-19 pandemic must be considered.