Comparison of effectiveness and comfort of two different configurations of a new total face mask for noninvasive ventilation (NIV): a randomized controlled trial

Interfaces are an important issue in treating patients with acute hypercapnic respiratory failure (AHRF) and advances have been made in the development of masks able to reduce rebreathing of exhaled carbon dioxide (CO2). We designed a randomized, crossover, physiological study to compare two configurations of a full face mask in terms of effectiveness (Arterial Blood Gases (ABGs) and respiratory rate (RR)) and comfort. Patients recovering from an AHRF episode were randomized to receive 1 hour trial with NIV using the same mask (DiMax®, DIMAR, Medolla, Italy) with two different configurations: the “standard one” with a single inlet and outlet (sDiMax) vs the same interface with a double inlet and outlet connection (DiMax Zero). A wash out period was allowed between the trials to obtain a value of PaCO2 not varying > 5 mmHg from the previous baseline. 9 COPD consecutive patients were studied. Baseline ABGs and RR were not different between the trials (i.e. PaCO2 71.3+8 mmHg vs 69+11 mmHg and 24.7+4 bpm vs 23.7+3.1 bpm, for sDiMax and DiMax Zero, respectively). After 1 hour of NIV, DiMax Zero was more effective than sDiMax in reducing PaCO2 (59.7+5.7 mmHg vs 64.7+12 mmHg p=0.02), while pH and PaO2 did not vary significantly. RR was significantly reduced with both mask settings, and patient’s comfort and tolerance were good and similar in both groups. The preliminary results of this crossover randomized trial showed that DiMax Zero was able to significantly reduce PaCO2 vs the sDiMax setting, while both configurations significantly reduced RR with similar patient’s comfort.