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Volume and pressure during transient added resistance.
J Green1, S T Chiang, W F Wang
1Institute of Physiology, National Yang-Ming Medical College, Taipei, Taiwan, Republic of China.
Respiration Physiology
|November 1, 1988
Summary
The added resistance method for measuring total respiratory resistance (Rrs) is valid. The study found that the change in driving pressure (delta Pt) is negligible during testing, making the method useful and simple.
Area of Science:
- Respiratory Physiology
- Pulmonary Function Testing
Background:
- Total respiratory resistance (Rrs) measurement methods are crucial for pulmonary diagnostics.
- The 'added resistance' method offers simplicity by not requiring total driving pressure (Pt) measurement.
- A key assumption is that the change in Pt (delta Pt) during added resistance is negligible.
Purpose of the Study:
- To evaluate the validity of the negligible delta Pt assumption in the added resistance method.
- To assess the clinical utility of the added resistance method for Rrs measurement.
Main Methods:
- Measured exhaled volume and total respiratory compliance (Crs) in healthy volunteers.
- Calculated the change in elastic recoil pressure (delta Pel, rs) and estimated the change in inspiratory muscle pressure (delta Pmus,I).
- Determined the total delta Pt by combining delta Pel, rs and delta Pmus,I.
- Assessed the effect of transient added resistance on intraesophageal pressure in COPD patients.
Main Results:
- The mean delta Pt in healthy volunteers was 0.045 cm H2O, found to be negligible.
- This delta Pt is small relative to resting expiratory pressures.
- No significant effect of transient added resistance on intraesophageal pressure was observed in COPD patients.
Conclusions:
- The assumption of negligible delta Pt is valid for the added resistance method.
- This method is practical and useful, especially when equipment and procedural simplicity are prioritized.
- The added resistance technique is a viable option for assessing Rrs.