Fig. 2. Increase in the main respiratory effort parameters: transdiaphragmatic pressure ( Pdi ), work of breathing ( WOB, J/l ), and pressure-time product of the respiratory muscles ( PTPes, cm H2O s min−1 ) with added dead space expressed in percentage of baseline value for the three modes: pressure support ventilation ( PSV ), adaptive ventilation ( ASV ), and adaptive pressure ventilation ( APV ). Note that no significant difference was observed between PSV and ASV. However, the increases with APV were significantly greater than those with PSV and ASV. * P < 0.05.