Respiratory work analysis is a diagnostic procedure in pulmonology (the study of the lungs) that can be used to determine changes in work of breathing in chronic pulmonary artery disease (COPD), among other conditions. Work of breathing is defined as the energy consumption, and therefore oxygen consumption, of the respiratory muscles required to overcome both elastic and resistive airway resistance. Both chronic and acute respiratory insufficiency can lead to increased dyspnea and respiratory drive, which can be (partially) compensated by increasing the work of breathing. With the help of this compensation mechanism, respiration remains in a physiological range for a longer period of time.
Indications (areas of application)
- Sleep apnea syndromes – In sleep apnea syndromes, which are characterized by nocturnal respiratory arrests and daytime sleepiness caused by this, a distinction is made between obstructive, central, and mixed forms. The most common form is obstructive sleep apnea syndrome (OSAS). Due to the obstruction of the upper airways, the work of breathing is increased in the short term, which can be determined with the help of the work of breathing analysis.
- Chronic obstructive pulmonary disease (COPD) – COPD is characterized by cough, increased sputum, and dyspnea (subjective shortness of breath) on exertion. Present obstruction (partial or complete closure of the lumen (diameter) of a hollow organ or a section of ductal or vascular systems) results in increased activity of the respiratory muscles associated with increased work of breathing.
- Bronchial asthma – Analogous to COPD, bronchial asthma causes airway obstruction but is fully or partially reversible.
- Kyphoscoliosis – In kyphoscoliosis, there is a lateral rotation parallel to a rotation of the spine. Due to the deformation of the spine, increased work of breathing is necessary for breathing, which can be determined by means of work of breathing analysis.
- Cystic fibrosis – In this disease, also known as cystic fibrosis, a viscous secretion occurs due to a genetic defect, which can not be removed by the fine hairs of the airways. Through this, in addition to the feeling of shortness of breath, an objectively measurable increase in the work of breathing can be detected.
- Neuromuscular diseases – As an example of a neuromuscular disease that can lead to an increase in work of breathing is myasthenia gravis.
- Ventilated patients – clinical studies have shown that measurement of work of breathing during weaning (ventilator weaning) of long-term ventilated patients may be useful and necessary. The procedure is used both to detect impending musculo-respiratory fatigue and to achieve improved respiratory muscle habituation.
Contraindications
If indicated, there are no contraindications to the performance of respiratory work analysis.
Before the examination
Depending on the underlying condition, respiratory work analysis represents part of the diagnostic methods for evaluating severity. For example, sleep apnea syndrome significantly increases the risk of developing cardiovascular diseases such as hypertension (high blood pressure), myocardial infarction (heart attack), and apoplexy (stroke), so further screening must be performed.
The procedure
The basic principle of respiratory work analysis is based on the measurement of respiratory work using an esophageal pressure probe. Respiratory work can be approximated via pressure determination by the esophageal pressure probe. However, since the work of breathing is performed by the respiratory muscles, the pressure measurement is a surrogate parameter (surrogate value). The contraction of the inspiratory respiratory muscles (muscles involved in inhalation) causes a reduction in pressure down to the negative range in the alveoli (pulmonary alveoli), which is due to an enlargement of the thoracic cavity (interior of the chest). Inhalation occurs due to this pressure negation or the pressure difference between the alveoli and the environment.
After the examination
Analysis of respiratory work allows assessment of improvement but also progression (progression) of diseases.As a result of the measurement results, additional therapeutic measures may need to be initiated depending on the disease present.
Possible complications
In the course of measuring the work of breathing using an esophageal pressure probe, injury to the esophagus, including esophageal rupture (rupture of the esophagus), may occur.
