Efficacy of a New Full Face Mask for Noninvasive Positive Pressure Ventilation: Results
Arterial blood gas analysis for each patient while breathing spontaneously and during NPPV with each of the three masks is shown in Figure 2. The mean PaC>2/Fl02 values during NPPV with each of the masks were higher (360 ±25, N; 346 ±19, NO; and 358 ±24, TFM) compared with eupnea (315 ±19, p<0.05), but not different among the different mask types. In contrast, mean РаСОг was significantly lower during NPPV with each of the masks (57 ±2, N; 58 ±3, NO; and 51 ±2, TFM) compared with eupnea (66 ± 4 mm Hg, p<0.05), but PaC02 was least with NPPV delivered via the TFM (p<0.01). The pH was greater during NPPV with all three masks compared with eupnea, but was greatest during NPPV with the TFM (7.41 vs 7.34, p<0.05).
The comparative effect of NPPV with the three different masks on ventilatory variables in each patient is shown in Table 3. Respiratory rate tended on average to be lower during NPPV compared with eupnea, but was not statistically significant. Expired minute volumes were also greatest with NPPV when compared with eupnea, but not different among the three masks. Expired tidal volumes were significantly greater with NPPV when compared with eupnea (p<0.05), and the exhaled tidal volume was greatest with the TFM (p<0.05). Inspired tidal volumes, inspiratory time and mean inspiratory flow, and duty cycle were significantly increased with the use of NPPV, when compared with eupnea (Table 3). Among the three masks, the duty cycle was least with the TFM (p<0.05) Here.
Figure 3 shows the degree of air leaks and the levels of discomfort with the face mask and dyspnea among the three masks in NPPV. There was a significant reduction (p<0.003) in air leakage when NPPV was delivered via the TFM (0.44 ±0.18) when compared with the N (1.89 ± 0.39) and NO masks (1.89 ± 0.35). The level of discomfort with the NPPV face mask was also least with the TFM (p<0.02). Finally, dyspnea was also significantly less in NPPV with the TFM (p<0.02) and N mask (p<0.05) in comparison to eupnea and NPPV with the NO mask.
Figure 2. Arterial blood gases in eupnea and NPPV with all three masks in all patients. Levels of ventilation were identical with all three different face masks in NPPV in each patient. Compared with eupnea, Pa02/FIc>2 (top panel) remained unchanged, but values for pH (p<0.001) (bottom panel) were greater and PaCC>2 (p<0.01) (center panel) were less in NPPV with all three masks. РаСОг tended to be least (p<0.01), however, and pH greatest (p<0.04) in NPPV with the total face mask (TFM) compared with the nasal (N) or nasal-oral (NO) masks.
Figure 3. Comparison of mask leaks, level of dyspnea, and patient discomfort with the face mask during NPPV with all three masks. As a group, the magnitude of mask leaks (p<0.003) and the level of discomfort with the face mask (p<0.02) were lowest in patients receiving NPPV via the TFM. The level of dyspnea, however, was significantly reduced when using either the nasal mask (p<0.05) or TFM (p<0.02).
Table 3—Inspired and Expired Ventilatory Variables During Eupnea and NIPPV With All Masks
|RR,b/m||Inspired Vt, ml||Inspired Ve, L/m||Expired Vt, ml||Expired Ve, L/m||Ti, s||Vt/Ti, L/s||Ti/Ttot|
|Eupnea||22 ±5||331 ±1||6.9 ±0.9||312±7||7.7 ±1.3||0.80 ±0.03||442 ±7||0.35 ±0|
|N||16±2||498 ±9||8.3±0.8||1026 ±30||16.2±3.7||1.74 ±0.08||622 ±10||0.46 ±.01|
|NO||16±2||537 ±13||8.8 ±0.8||1352 ±83||15.8±2.6||1.74 ±0.07||742 ±15||0.49 ±.01|
|TFM||16±2||804±10||12.0±1.6||1137 ±24||18±3.7||1.40 ±0.02||839± 16||0.40 ±0|
Category: Respiratory Symptoms
Tags: face mask, hypercapnia, noninvasive ventilation, respiratory failure