The term describes the maximal pressure generated during inspiration against a closed airway. This measurement, typically expressed in centimeters of water (cmH2O), reflects the strength of the inspiratory muscles and the patient’s ability to create a vacuum within the thoracic cavity. A more negative value indicates greater inspiratory muscle strength; for example, a measurement of -80 cmH2O demonstrates significantly stronger inspiratory effort than a measurement of -20 cmH2O.
Evaluating the strength of the inspiratory muscles offers valuable insights into respiratory function. The ability to generate adequate negative pressure is crucial for effective ventilation and airway clearance. Its assessment can aid in diagnosing respiratory muscle weakness, monitoring disease progression, and predicting the success of weaning from mechanical ventilation. Clinically, it has been used for decades as a relatively simple and non-invasive tool in pulmonary function assessment.
