Background
Patient compliance and efficacy of the ventilator used for non-invasive ventilation (NIV) are important determinants of successful treatment.
Method
In this pilot study, healthy volunteers were requested to breathe normally for 10 min through a close fitting facemask. Each volunteer was ventilated using three ventilators, Galileo (Hamilton Medical, Germany) - pressure support ventilation (PSV), Harmony S/T (Respironics, USA) - pressure ventilation and Breas PV403 (Breas Medical, Germany) - volume control ventilation (VCV), for a duration of 10 min in a random order. The CO2SMO Plus respiratory profile monitor (Novametrix Medical, USA) linked to a computer was used to measure minute alveolar ventilation (MValv), intrinsic positive end expiratory pressure (PEEPauto), imposed work of breathing (WOBimp), end-tidal Carbon dioxide (ETCO2) in the second 5 min of each episode of ventilation. Visual analogue scale (VAS) for comfort during NIV from seven volunteers was recorded. Repeated measures ANOVA was used to analyse multiple comparisons.
Results
Thirteen healthy adult volunteers (five male, eight female) aged 22–48 years were studied. Data obtained from the study are displayed in Tables 1 and 2.
Table 1.
Comparison of Harmony, Galileo and Breas (mean [SD], median [interquartile])
| Baseline | Harmony | Breas | Galileo | |
|---|---|---|---|---|
| MValv | 7.48 (0.90) | 9.42 (2.08)‡ | 6.72 (1.83) † | 7.11(1.74) |
| PEEPauto | 0.00 | 0.44 (0.13–1.36)* | 3.58 (3.06–4.04)*†‡ | 1.23 (0.73–1.36)* |
| WOBimp | 0.00 | 0.00 | 0.25 (0.10–0.37)*†‡ | 0.00 |
| Vd/Vt | 0.30 (0.03) | 0.33 (0.05) | 0.31 (0.06) | 0.32 (0.06) |
| VCO2 /kg | 2.74 (0.45) | 2.28 (0.40) | 2.50 (0.55) | 2.49 (0.49) |
| ETCO2 | 5.19 (0.38) | 4.25 (0.62)* | 4.55 (0.66)* | 4.02 (0.55)* |
*P < 0.05 compared with baseline. †P < 0.05 compared with Harmony. ‡P < 0.05 compared with Galileo.
Table 2.
Comfort VAS scores (0–10) for normal ventilation, Galileo, Harmony and Breas
| Baseline | Galileo | Harmony | Breas | |
|---|---|---|---|---|
| Median | 7.8 | 6.9‡ | 8 | 2.3*†‡ |
*P < 0.05 compared with baseline, †P < 0.05 compared with Galileo, ‡P < 0.05 compared with Harmony.
Conclusion
In normals, VCV with the Breas was less comfortable than the pressure ventilation modes tested. The increased autoPEEP and WOBimp may reflect this. There is also a suggestion that the auto-track triggering on the harmony may have enhanced comfort in normals when compared to the preset flow triggering on the Galileo.