Nasal NPPV in not useful for patients who cannot keep their mouth shut. In order to initiate the process of NPPV, a chin strap can be tried even though patients tend to breathe through their mouths. These patients are referred to as dyspenic patients. The best option for such patients is to change to a full face mask and a ventilator that can provide precise FIO2 and display waveforms. When the patient reports an oral dryness, a low resistance, heated modifier should be added to the set up. The importance of adding heated humidity is that it improves the patient compliance with the therapy.
In addition, 5cm of water PEEP is not adequate to maintain stable alveoli. To tackle this one should increase peep to 10 cm of water.
This approach is known as the low-high approach. One starts with a lower IPAP of between 5-10 cmH2O. This is gradually increased to achieve alleviation of dyspenia, increased volume of tide, reduced respiratory rate, and patient-ventilator synchrony. The ideal setting for such at 3-4cmH2O, unless the patient has a significant amount of autopeep which in other words is known as PEEPi. This patient falls in this category, and we are advised to start the EPAP at 5cm water. The FiO2 is then titrated to keep the pulse oximetry equal to or greater than 90 %. Just like the conventional ventilation, the EPAP is flexible enough. It can be adjusted to improve oxygenation and also to create higher minute ventilation and in the process mitigate against hypercanpia.
The patient should be closely monitored to access the failure or success of the therapy. This involves checking the blood gases within 1one to two hours after initiation of NPPV. If the patient does not respond to the adjustments made, he should be considered for intubation.