MA

Pressure Gradient in Breathing

Compliance= stretchability

  • How abe are the lungs to expand to receive the volume?

  • During inhale

  • Do they stretch easily (high)

  • Are they stiff, hard to fill and don’t stretch easily (low)

    • Pulmonary Fibrosis=Scarring of lung tissue

    • The scar tissue makes the lung tissue thicker, stiffer, and elastic

    • Result: in lower compliance (lungs don’t expand easily)

    • Leads to shallow rapid breathing.

    • Hypoxemia.

Elastance: recoil ability

  • The ability of the lung to return to their original size after being stretched/filled

  • Emphysema: floppy lungs

    • Low elastance, high compliance, hyperinflation.

  • Transrespiratory pressure:

    • The pressure difference between the atmosphere (outside air) and the alveoli (inside the lungs)

    • Role: Its the driving pressure for airflow in or out of the lugns.

    • Clinical link: when we place someone on mechanical ventilation the ventilator creates this gradient by pushing air in.

  • Transairway pressure:

    • The pressure diffrence between the airway opening (mouth/nose or endotracheal tube) and the alveoli.

    • Role; It represents the force needed to overcome airway resistance (like in asthma)

  • Transalveolar pressure:

    • The pressure difference between the alveoli and the pleural space.

    • Role: keeps the alveoli open and prevents them from collapsing

    • Clinical Link: In ARDS or atelectasis, this pressure is too low and alveoli collapse.

  • Transpulmonary pressure:

    • The pressure difference between the alveoli and pleural space (often used interchangeably with transalveolar)

    • Role: Represents the distending pressure of the lung how much the lungs want to expand.

    • Clinical link: In Mechanical ventilation, we monitor this to prevent over distention (barotrauma)

  • Transthoracic Pressure:

    • The pressure difference between the alveoli and the body surface

    • Role: Shows how much muscle effort is required from the chest wall to expand the lungs

    • Clinical Link: In patients with obesity or chest wall restriction, this pressure increases because it takes more effort to breathe.