[Effects of negative extra-thoracic pressure ventilation on extravascular lung water volume and central blood volume...

In negative extra-thoracic pressure ventilation (NETPV), lung water volume and central blood volume (CBV) could increase because of increased venous return and intensified negative interstitial pressure. The effects of NETPV on the extravascular lung water and CBV were examined in ten normal dogs by the double-indicator method using Na and cold water. The lung water volume measured by the method (EVTV) was compared with the lung water volume measured by the gravimetric method (EVLW) in 17 dogs. EVTV did not show any significant change in any ventilation modes compared with IPPV. CBV decreased from 21.9 ml.kg-1 to 19.2 ml.kg-1 in CPPV compared with IPPV (P less than 0.05). EVTV correlated well (r = 0.91, P less than 0.001) with EVLW. In normal dogs, NETPV did not change the lung water volume and CBV. NETPV dogs do not seem to have any disadvantage in respect of lung water volume compared with conventional positive pressure ventilations.