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Winters's formula, [1] named after R. W. Winters, [2] is a formula used to evaluate respiratory compensation when analyzing acid-base disorders in the presence of metabolic acidosis. [ 3 ] [ 4 ] It can be given as:
The normal relaxed state of the lung and chest is partially empty. Further exhalation requires muscular work. Inhalation is an active process requiring work. [4] Some of this work is to overcome frictional resistance to flow, and part is used to deform elastic tissues, and is stored as potential energy, which is recovered during the passive process of exhalation, Tidal breathing is breathing ...
In those with acute respiratory failure on mechanical ventilation, "the static compliance of the total respiratory system is conventionally obtained by dividing the tidal volume by the difference between the 'plateau' pressure measured at the airway opening (PaO) during an occlusion at end-inspiration and positive end-expiratory pressure (PEEP ...
Lung compliance is an important measurement in respiratory physiology. [2] [3] Decreased pulmonary compliance may be associated with fibrosis. Increased pulmonary compliance may be associated with COPD and emphysema due to loss of alveolar and elastic tissue. Pulmonary surfactant increases compliance by decreasing the surface tension of water.
A RSBI score of less than 65 [3] indicating a relatively low respiratory rate compared to tidal volume is generally considered as an indication of weaning readiness. A patient with a rapid shallow breathing index (RSBI) of less than 105 has an approximately 80% chance of being successfully extubated, whereas an RSBI of greater than 105 virtually guarantees weaning failure. [4]
The respiratory quotient (RQ or respiratory coefficient) is a dimensionless number used in calculations of basal metabolic rate (BMR) when estimated from carbon dioxide production. It is calculated from the ratio of carbon dioxide produced by the body to oxygen consumed by the body, when the body is in a steady state.
The amount of respiratory compensation in metabolic acidosis can be estimated using Winters' formula. [2] Hyperventilation due to the compensation for metabolic acidosis persists for 24 to 48 hours after correction of the acidosis, and can lead to respiratory alkalosis. [3] This compensation process can occur within minutes. [4]
In fluid dynamics, the Hagen–Poiseuille equation is a physical law that gives the pressure drop in a fluid flowing through a long cylindrical pipe. The assumptions of the equation are that the flow is laminar viscous and incompressible and the flow is through a constant circular cross-section that is substantially longer than its diameter.