ANALYSIS OF RESPIRATORY MECHANICS DURING ARTIFICIAL-VENTILATION

Mechanical or artificial ventilation is the most important life-saving therapeutic instrument in modern intensive care medicine. The ventila tor takes on the convective transport of the respiratory gas, i.e. del ivery of oxygen and removal of carbon dioxide. The technical gas deliv ery system (ventilator, respiratory tubing system, gas humidifier) and the respiratory system (lungs and thorax) of the patient form a conne cted pneumatic system of high complexity. The respiratory system produ ces a mechanical impedance to ventilator output. Impedance is composed of an elastic, a non-elastic, i.e. resistive, and an inertive part. T he corresponding indices describing respiratory mechanics are complian ce, flow resistance and inertance. Based on the equation of motion of the respiratory system, several methods of analysing respiratory mecha nics during mechanical ventilation are described. Quantitative analysi s of respiratory system mechanics (a)is a prerequisite for the underst anding of the complex patient-ventilator interaction, (b) provides imp ortant clinical information on pulmonary function and the course of di sease, and (c) allows the physician at the bedside to adjust the venti latory settings to the needs of the individual patient.