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The average total lung capacity of an adult human male is about 6 litres of air. [1] Tidal breathing is normal, resting breathing; the tidal volume is the volume of air that is inhaled or exhaled in only a single such breath. The average human respiratory rate is 30–60 breaths per minute at birth, [2] decreasing to 12–20 breaths per minute ...
The difference between the highest values of two FVCs need to be within 5% or 150 mL. When the FVC is less than 1.0 L, the difference between the highest two values must be within 100 mL. Lastly, the difference between the two highest values of FEV1 should also be within 150 mL. The highest FVC and FEV1 may be used from each different test.
Average values for FEV1 in healthy people depend mainly on sex and age, according to the diagram. Values of between 80% and 120% of the average value are considered normal. [14] Predicted normal values for FEV1 can be calculated and depend on age, sex, height, mass and ethnicity as well as the research study that they are based on.
The value of respiratory rate as an indicator of potential respiratory dysfunction has been investigated but findings suggest it is of limited value. Respiratory rate is a clear indicator of acidotic states, as the main function of respiration is removal of CO 2 leaving bicarbonate base in circulation.
The respiratory quotient value indicates which macronutrients are being metabolized, as different energy pathways are used for fats, carbohydrates, and proteins. [1] If metabolism consists solely of lipids, the respiratory quotient is approximately 0.7, for proteins it is approximately 0.8, and for carbohydrates it is 1.0.
Lung volumes. Functional residual capacity (FRC) is the volume of air present in the lungs at the end of passive expiration. [1] At FRC, the opposing elastic recoil forces of the lungs and chest wall are in equilibrium and there is no exertion by the diaphragm or other respiratory muscles.
Minute ventilation (or respiratory minute volume or minute volume) is the volume of gas inhaled (inhaled minute volume) or exhaled (exhaled minute volume) from a person's lungs per minute. It is an important parameter in respiratory medicine due to its relationship with blood carbon dioxide levels .
A human's vital capacity depends on age, sex, height, mass, and possibly ethnicity. [4] However, the dependence on ethnicity is poorly understood or defined, as it was first established by studying black slaves in the 19th century [ 5 ] and may be the result of conflation with environmental factors.