Objective To evaluate the effects of different inspiratory flow waveforms on the respiratory function of patients with severe exacerbation of asthma during mechanical ventilation. Methods Twenty-one patients with severe exacerbation of asthma were ventilated with square waveform and decelerating waveform respectively for 30 minutes when the tidal volume was set at 6 mL/ kg, 8 mL/ kg and 10 mL/ kg in ICUof Zhejiang Hospital of Integrated Traditional Chinese and Western Medicine fromJanuary 2006 to December 2007. Meanwhile shunt fraction ( Q·S /Q·T ) , dead space value ( VD/VT ) , airway peak pressure ( Ppeak ) , plateau pressure ( Pplat) ,intrinsic positive end-expiratory pressure( PEEPi) and arterial blood gas analysis were measured. Results The Q ·S /Q·T in the decelerating waveformgroup was less than that of the square waveform group( P  lt;0. 05) when tidal volume was set at 6 mL/ kg. When tidal volume was set at 10 mL/ kg, PEEPi and VD /VT in the decelerating waveform group were higher than those of the square waveform group. On the contrary, the Ppeak was lower than that of square waveform group( P  lt; 0. 05) . Conclusion For patients with severe exacerbation of asthma treated with mechanical ventilation, decelerating waveform is preferable at low tidal volume( 6 mL/ kg) , and square waveform is preferable at high tidal volume( 10 mL/kg) .

Citation： LI Guohui,FANG Kun,JIA Xusheng. Effects of Different Inspiratory Flow Waveforms on the Respiratory Function of Patients with Severe Exacerbation of Asthma During Mechanical Ventilation. Chinese Journal of Respiratory and Critical Care Medicine, 2009, 09(1): 40-42. doi: Copy