CROSS-TALK BETWEEN THE LUNGS IN PIGLETS

Hypothesis: During alternating ventilation (AV) (i.e. differential ven tilation (DV) of both lungs with a phase difference of half a ventilat ory cycle) volume expansion of the inflated lung will occur partly by compression of the opposite lung. Objective: We studied whether and ho w large an undulating flow would occur out of and into the non-ventila ted lung during unilateral ventilation. Design: In 20 anaesthetized, p aralysed piglets (11.0+/-1.0 kg) DV was applied at a rate of 10 breath s per minute (bpm). In 6 animals, 15 and 20 bpm were also applied with the tidal volume adapted no normocapnia. As the measure of interactio n (cross-talk) served the vol ume change in the non-ventilated lung, f ound by integration of the low signal, in percentage of the tidal volu me to the other lung, Results: In all pigs, tidal volume to the left l ung (V-T,V-l = 7.33 +/- 1.06 ml kg(-1)) caused a volume change in the right lung of about 21% of V-T,V-l at 10 bpm. The right-to-let cross-t all; was significantly lower and about 15% of V-T,V-l (9.07 +/- 1.21 m l kg(-1)). At higher ventilatory rates, the 1-to-r and the r-to-1 cros s-talk did not change. Conclusion: During unilateral ventilation, volu me expansion of the inflated lung occurs partly by compression of the opposite lung. The lower mean lung volume during AV compared to synchr onous differential ventilation can be explained by such compression. T he mechanism of compression is similar at different ventilatory rates.