Although mechanical ventilatory support in the 1980s clearly provides adequate gas exchange with minimal side effects, there remains a need for ventilation and oxygenation in those with severe gas exchange abnormalities, for reduced airway pressure effects in those at risk for barotrauma, for a better muscle reconditioning approach in those with muscle dysfunction, and for better ventilator-patient interactions (synchrony) in many patients receiving mechanical ventilatory support. The new approaches outlined previously address these issues. However, research and development for new and better techniques are needed. Specific areas that require better understanding include the effects of intrathoracic pressure on the lungs and the circulation, the matching of ventilation and perfusion under different support modes, the function of the respiratory muscles during fatigue and recovery, and the ventilatory reflexes operational during mechanical ventilation. Only with this information can we design the optimal ventilatory support system.