Factors that affect Respiratory Volume

The average adult takes 12 to 15 breaths per minute under normal conditions. A breath is a full breathing cycle that includes one inspiration and one expiration.

The volume of air that passes into and out of the lungs is measured using a spirometer, and the process of obtaining the measurements is known as spirometry. Respiratory (pulmonary) volumes are an essential component of pulmonary function testing because they can provide information about the physical state of the lungs.

Respiratory volume and capabilities are influenced by factors such as age, gender, body type, and physical training. Lung capacity typically peaks in early adulthood and declines with age after that.

What is Respiratory System?

Humans have a pair of external nostrils that protrude over the top lips and lead to two nasal cavities. The nasal septum is a cartilaginous septum that separates the nasal cavities. The air then enters the trachea through the mouth, larynx, and trachea. The trachea is divided further into the right and left bronchi, which enter the right and left lung, respectively. Bronchi in the lungs continue to split into little branches known as bronchioles. Alveoli can be seen at the ends of terminal bronchioles. Alveoli are small air sacs that allow gases to circulate.

What is Respiratory Volume?

Respiratory volume is also known as Lung volume. It is the amount of gas in the lungs at any particular point in the respiratory cycle. Lung capacities are calculated by adding together distinct lung volumes. An adult male’s entire lung capacity is around 6 litres of air. The assessment of lung volumes is an essential component of the pulmonary function test. These quantities fluctuate according to the depth of breathing, ethnicity, gender, age, body composition, and certain respiratory diseases. Spirometry can measure many lung volumes, including tidal volume, inspiratory reserve volume, and expiratory reserve volume. However, body plethysmography, nitrogen washout, and helium dilution techniques are used to determine residual volume, functional residual capacity, and total lung capacity.

Factors that affect Respiratory Volume

Anthropometric parameters such as weight, height, sex, and age affects Respiratory Volume.

Age

Historically, one of the most important elements in determining respiratory volume was age. At around 20–25 years of age,26 pulmonary maturity is attained, after which respiratory system performance gradually declines.

The main impacted variables are forced vital capacity (FVC) and forced expiratory volume in one second (FEV1), which decrease with age28 because to decreasing chest wall compliance, loss of expiratory muscular power, and a rising propensity of the smaller airways to close during forced expiration.

29 FEV1 drops by around 20ml/year between the ages of 25 and 39 years, then steadily increases until it reaches 35ml/year at the age of 65.30

Height

Height influences several measures, including TLC, VC, RV, FVC, and FEV1, because they are related to body size. This indicates that in tall people, who have larger respiratory or lung capacity, respiratory or lung volume decreases at a faster pace than in shorter people as they age. Peak expiratory flow is also higher in taller people, and prediction formulae like the Wright scale, the IN1382, or the NHANESIII are commonly utilised in clinical practise. Finally, in gas exchange, DLCO levels have been observed to rise with height.

Sex

Standard morphometric techniques demonstrate that, among people of the same weight and height, males have bigger lungs than women, resulting in a greater number of bronchi, a larger alveolar surface area, and a wider airway diameter.

In terms of physical activity, women’s smaller airway diameter and lung sizes result in lower peak expiratory flows. As a result, women have a substantially lesser capacity than males to increase ventilation during exercise. However, neither men nor women achieve their peak effective ventilation during really hard physical exertion, though women get closer than men.

Weight

Some factors, like as FRC and ERV, fall rapidly as weight increases, to the point that tidal volume in morbidly obese people can be comparable to RV.

Variables like as FRC and expiratory reserve volume (ERV) have been seen to decrease rapidly with increasing BMI, to the point that VT in morbidly obese individuals can approach RV. The FRC might go so low that it is exceeded by the closure capacity. This phenomenon has clinical relevance since it can cause lung collapse and atelectasis in the lower lung zones, resulting in a non-uniform distribution defined by gas exchange occurring largely in the upper zones.

Conclusion

Respiratory volumes are an essential component of pulmonary function testing because they can provide information about the physical state of the lungs. The trachea is divided further into the right and left bronchi, which enter the right and left lung, respectively. Respiratory volume is also known as Lung volume. It is the amount of gas in the lungs at any particular point in the respiratory cycle. The assessment of lung volumes is an essential component of the pulmonary function test. One of the most important elements in determining respiratory volume is age. Some factors, like as FRC and ERV, fall rapidly as weight increases, to the point that tidal volume in morbidly obese people can be comparable to RV.