Mechanics of ventilation

How the lung is supported and moved

Pneumothorax of right lung

Rotation axis

ribs

Static recoil

Interpleuralpressure

Air

flow

insp exsp

Interpleural

pressure

Tidal volume

P=T/r

↑r ↓T

P = P

↓CL

Dipalmitol fosfatidil cholin + protein

Alveoli are larger at the apex (upper panel) than base (lower)

∆V

∆P

C = ∆V / ∆P

∆P

∆V.

R=∆P / ∆V.

Number of airways increases rapidly with generation

Mechanism of dynamic compression

Work done on the lung during breathing

Transport of gas from alveoli to blood

GasMembraneblood

0.5 μm

Very thin blood-gas barrier

Limitation byperfusion

Limitation bydiffusion

Respiration at the limit: Respiration at the limit: surviving on the summit of Mt surviving on the summit of Mt

EverestEverest

Highest altitudes attained in the last century

Maximum oxygen uptake at increasing altitudes

Climbers Ranked by their Hypoxic Ventilatory Response

Alveolar Pco2 at Extreme

Altitudes

Pulmonary Gas Exchange on the Everest Summit

O2 Dissociation Curves in High-Altitude

Mammals

Decrease of barometric pressure with altitude

Climber on the Everest Summit

Polycythemia at 4600 m altitude

• Hemoglobin concentration 19.8 g/dl

• Arterial PO2 45 mm Hg

• O2 saturation 81%

• O2 concentration 22.4 ml/dl

DLO2 = VO2 / PAO2 Pc O2

DLCO = VCO / PACO

Time of blood flow through pulmonary capillary