Application Of Various Measurements Of Respiratory System Functioning In Modern Clinical Practice
Respiratory System
Respiratory system provides the exchange of gases between blood and the atmospheric air, which is important for the functioning of all cells of the body. It can be divided into two parts which consist of the upper and the lower respiratory tract. The nostrils, nasal cavity, pharynx, and larynx, which are responsible for trapping the dust in the air and its conduction into the lower respiratory tract. Besides, there are number of reflexes protecting the other part of the system as well as organism within the upper respiratory tract. They include sniffing and sneezing to remove foreign particles from the nasal cavity, aspiration reflex of pharynx expiration reflex of larynx to prevent large objects from entering and blocking the trachea (Widdicombe, 2011). Therefore, the major reflexes of the upper respiratory tract meet the function of this part of the system to conduct air and to prevent blockage of the lower tract.
The lower respiratory tract consists of trachea, bronchi, and lungs. The trachea is a C-shaped tube formed by cartilage rings with their free side turned towards the esophagus to allows for the passage of food along it. The lining of trachea is represented by ciliated epithelial cells and goblet cells producing mucus. The continuous beating of cilia allows for efficient removal of foreign particles trapped by the mucus. The importance of this mechanism is underlined by pathological condition known as cystic fibrosis, when abnormality in chlorine channels within the tracheal lining prevents from the income of water for making mucus less viscous. As a result, the trapped particles cannot be effectively removed by the beating of cilia, and rather move into the bronchi and lungs, leading to increased frequency of respiratory infections in the patients (Jones, Fosbery, Gregory & Taylor, 2013).
Bronchi are formed by bifurcation of the trachea and gradually divide into smaller tubules called bronchioles as they enter the lungs. The diameter of these structures can change in response to conditions of the internal and external environment (Hall & Guyton, 2016). Therefore, both trachea and bronchi are mainly responsible for the conduction of air to the lungs, which is the organ participating in gas exchange directly.
The lungs are paired organs containing two lobes at the left side of the body and three lobes at the right one. This difference is explained by the location of the heart within the thoracic cavity (Hall & Guyton, 2016). The structural and functional unit of lungs is the alveolus. It is a tiny sac with a one cell thick wall, which is highly vascularized. Such organization contributes to the efficient exchange of gases by means of diffusion, because the thickness of membrane is the minimum, while the surface area is high. In addition, the inner surface of the alveoli is covered with surfactant, which lubricates them, prevents from collapse of the alveolar walls, and dissolves gases for more efficient diffusion (Hall & Guyton, 2016).
The flow of air into and out of the lungs is directed by changes in volume of the organ caused by changes in volume of the thoracic cavity. During inspiration, the diaphragm contracts and moves downwards, while internal intercostal muscles contract to expand the rib cage. The increase in volume of the thoracic cavity leads to decrease in pulmonary pressure, which allows the lungs to expand and fill with the air. Due to concentration gradient, oxygen from the atmospheric air diffuses into the blood, while carbon dioxide enters the alveoli to be exhaled. In an upwards position at rest, the only muscle, expiration is a passive process.
The diaphragm relaxes and moves upwards, while gravity force causes the rib cage to move down. It leads to decrease in volume, which in turn causes increase in pressure forcing the air out of the lungs. However, in horizontal position, gravity cannot provide the movement of rib cage in the proper direction for the occurrence of expiration, and thus, external intercostal muscles have to contract. During intense physical activity, the assessor muscles of neck, back, and abdomen also participate in breathing movements to make them more intense and frequent. Therefore, the lungs, alveoli, and breathing mechanisms are properly adapted to their functions.
The functioning of tracheobronchial tree and lungs is regulated by respiratory centers of medulla oblongata and pons, as well as local reflexes. The ability of respiratory centers to regulate the frequency of breathing is based on sensation of concentration of hydrogen ions in blood, which is an indicator of carbon dioxide concentration, by central chemoreceptors (Hall & Guyton, 2016). An example of local regulation is Herring-Breuer reflex, which prevents over-inflating of lungs during inspiration. The increased stretching of bronchioles and lungs leads to inhibition of inspiration and initiation of expiration. There are also peripheral chemoreceptors, associated with C-fibers, which detect concentration of carbon dioxide and other substances, and change the breathing rate accordingly (Coleridge & Coleridge, 2011). Thus, most reflexes of the tracheobronchial tree and lungs are directed for regulation of breathing rate, as well as maintenance of lung integrity.
The functioning of the respiratory system can be evaluated for the detection of pathological states. Diseases of this system are usually associated with changes in the state of alveoli or efficiency of air flow into them due to blockage of airways, which in turn affects the volume of air present in the lungs or entering them. In addition, the measured values could be used as an indicator of disease progression and efficiency of the treatment process. Therefore, several measurements and related instrumentation have been developed. They include vitalography, spirometry, peak flow mete, and breath-holding abilities. Tidal volume, vital capacity, inspiratory and expiratory reserve volumes can be measured with the help of spirometry, while vitalography is used for the estimation of forced vital capacity and forced respiratory volume (Flesch & Dine, 2012). These parameters of lung functioning can be estimated for early diagnosis of chronic obstructive pulmonary disease, which can be hardly identified initially. However, application of vitalography ensures 100% sensitivity. Spirometry can be applied to differentiate between this condition and bronchiestasis, which has similar symptoms. Peak flow meter is the irreplaceable device for people suffering from asthma, because it allows for easy identification of how well air enters the lungs. Therefore, application of various measurements of respiratory system functioning is relevant for the modern clinical practice. The aim of the current paper was to master the mentioned methods and to identify patterns and correlations associated with them.
Methods
First, general information was collected about the participants, primarily their height, age, weight, and gender. Then, estimation of respiratory system functioning was conducted. During measurements, the nose of the participant was closed with a clip to prevent from air leakage through it during expiration. He/she was asked to breath normally before the start of measurement. The lips of the participant were tightly wrapped around the mouthpiece of the device and he/she was asked to follow the instructions of the experimenter. In case of spirometry, it was required to make a common exhalation, the maximum possible exhalation or inhalation after the typical one, or to breath in the maximum amount of air and to expel it. These allowed for the estimation of tidal volume, vital capacity, inspiratory and expiratory reserve volumes. In addition, the respiratory rate of the participant was calculated.
During vitalography, forced expiratory volume and forced vital capacity were measured while peak flow meter was used to estimate the force of air in liters per minute, which moves through the respiratory system. The mentioned devices register the volume of air passing through them and show it in the specific units, typically liters. The mouthpiece of the applied devices was cleaned after each participant. In addition, the breath holding exercise was performed, when the participants were asked to hold breath after expiration and inspiration under the normal state, as well as after hyperventilation. Time, for which they could hold the breath was estimated and recorded as well as measurements identified with other devices. The obtained data were analyzed in R statistical software with the use of descriptive statistics, correlation, and group comparison tests.
Results
In total, 39 participants (46% females) took part in the study. The basic demographic characteristics measured for these persons included age, height, and weight. Then, analysis of correlation or difference between certain groups of data was performed. First, correlation between peak flow and weight was assessed with the help of Pearson test. It was identified that weight shows relatively strong statistically significant relationship with peak flow at t=5. 2.
