[Difference between single hole exhalation valve and plateau exhalation valve when used in patients treated with BiPAP Vision ventilator for chronic obstructive pulmonary disease with hypercapnia]

To observe difference in clinical effect between single hole exhalation valve and plateau exhalation valve when used in patients treated with BiPAP Vision ventilator for chronic obstructive pulmonary disease (COPD) with hypercapnia.

Forty seven patients with hypercapnia due to COPD, who were admitted to the central intensive care unit (ICU) in the First Affiliated Hospital of Chongqing Medical University from October 2008 to July 2010, treated with noninvasive positive pressure ventilation (NIPPV) by BiPAP Vision ventilator, were enrolled in the study. The patients were divided randomly into NIPPV with application of single hole exhalation valve group (n=22) and plateau exhalation valve group (n=25). In each group, parameters of the arterial blood gas, including arterial partial pressure of oxygen (PaO(2)) and arterial partial pressure of carbon dioxide (PaCO2), were measured at the time points of 0, 2, 4, 8, 24, 48 hours of NIPPV and 24 hours post NIPPV.

The general conditions were similar in both groups at 0 hour. Compared with that of 0 hour, marked improvement in PaO(2) (mm Hg, 1 mm Hg=0.133 kPa, single hole exhalation valve group: 70.4±10.2, 78.7± 10.4, 82.6±9.2, 86.5±9.6, 90.4±9.0, 91.3±8.9 vs. 57.2±16.4; plateau exhalation valve group: 71.1±12.3, 77.9±11.6, 83.3±8.9, 85.9±8.2, 89.4±8.2, 92.1±8.5 vs. 56.9±17.2) and obvious lowering of PaCO(2) (mm Hg, single hole exhalation valve group: 76.3±11.9, 74.1±12.7, 71.3±11.2, 67.4±10.5, 65.4±8.2, 61.4±7.9 vs. 85.7±19.2; plateau exhalation valve group: 72.6±10.5, 70.1±11.5, 67.4±10.1, 63.9±9.7, 62.8±7.7, 59.1±7.3 vs. 86.3±17.9) were observed at the time points of 2, 4, 8, 24, 48 hours of NIPPV and 24 hours post NIPPV in both groups (all P<0.05). Comparing single hole exhalation valve group with plateau exhalation valve group, PaO2 showed no statistical significance at the same time point (all P>0.05). However, PaCO(2) was significantly lower in plateau exhalation valve group than that in single hole exhalation valve group at the time points of 2, 4, 8 and 24 hours (all P<0.05).

During BiPAP Vision ventilator in NIPPV treatment of patients with COPD complicated with CO2 retention , single hole exhalation valve and plateau exhalation valve both resulted in marked improvement in PaO2 and obvious decrease in PaCO2. Plateau exhalation valve corrected CO2 retention more quickly and effectively than side hole exhalation valve probably by preventing CO2 rebreathing by the patients.