Age-dependent cardiopulmonary interaction during airway obstruction: a simulation model

Area of Science:

• Cardiopulmonary physiology
• Geriatric medicine

Background:

• Inspiratory fall in arterial blood pressure (Pa) during airway obstruction is typically attributed to ventricular interdependence, afterload, and intrathoracic pressure transmission.
• This phenomenon is significantly reduced in the elderly, but the reasons are not well understood.

Purpose of the Study:

• To investigate the underlying mechanisms for the reduced inspiratory fall in arterial blood pressure observed in older adults during airway obstruction.
• To compare cardiopulmonary responses to inspiratory loading in young and elderly individuals using a mathematical model.

Main Methods:

• Experimental comparison of inspiratory loading effects in young and older subjects.
• Development and utilization of a beat-by-beat mathematical model simulating cardiopulmonary variables.
• Simulation of increased arterial and left ventricular elastance parameters in the older group.

Main Results:

• Simulations closely correlated with experimental arterial blood pressure (Pa) data.
• A significantly larger (38%) linear increase in left ventricular transmural pressures with negative intrathoracic pressure was identified in older subjects.
• Increased ventricular elastance parameters in older subjects explained the reduced Pa fall.

Conclusions:

• The reduced fall in arterial blood pressure during airway obstruction in the elderly is linked to increased left ventricular elastance and transmural pressures.
• This apparent perfusion preservation may be misleading, masking increased afterload and diastolic dysfunction in older individuals.