This invention is a novel method and apparatus for greatly improving and sustaining spontaneous breathing in patients with severe respiratory failure. Continuous positive airway pressure (CPAP) is widely used in the treatment of patients with mild respiratory failure. The constant back pressure in CPAP provides the force to expand some diseased parts of the lungs and, thus, improve oxygenation and carbon dioxide removal; however, presently available CPAP systems have limitations when used in patients with more severe respiratory failure who need endotracheal tubes, which have substantial airway resistance as compared to upper airway resistance. This resistance can lead to an increase in the work of breathing and cause fatigue. Too often, a patient with an ETT receiving CPAP treatment is eventually placed on a mechanical ventilator, increasing his or her risk of morbidity and mortality. The peak inspiratory and respiratory air flows in current CPAP systems also is severely limited. This contributes to patient discomfort and often becomes the motivation for switching a patient to a mechanical ventilator. This new CPAP system offers significant improvements over previous systems because it combines a passive CPAP apparatus with an intratracheal pulmonary ventilation (ITPV) system. The ITPV system has exceptionally low extrinsic resistance to air flow and greatly reduces dead-space ventilation. This system will permit a large fraction of the current patient population supported by assisted mechanical ventilation to switch to CPAP or a combination of CPAP and ITPV, significantly reducing the risk of morbidity and mortality.