Disease specific alterations in pulmonary physiology and appropriate ventilation

Knowledge of the pulmonary physiology and the pathologic alteration in the disease states is essential to scientifically rationalizing the ventilatory strategy. It is the interplay of compliance, resistance and the time constants, which vary with the disease due to their diverse pathologies. Preterm babies are born with physiological handicap due to low surfactant levels, which makes their lungs stiff and hence low compliance. Low compliance states result in under-inflation of lungs and ventilatory strategies are directed towards maintenance of functional residual capacity with optimal positive end expiratory pressures and peak inspiratory pressures. In contrast, high resistance states are associated with hyperinflation and requires low pressures. The present text deals with the normal physiology, alternations in pulmonary physiology in disease states and ventilatory strategies for different diseases.