Dopamine is frequently used as an inotropic drug to elevate cardiac output. In addition to the beneficial cardiac effect of this drug, the few previous studies addressing its ability to alter the airway tone reported controversial results.

Thus, the investigators aimed at clarifying the potential of dopamine to alter gas exchange outcomes and the airway tone in patients undergoing cardiac surgeries with cardiopulmonary bypass.

Blood gas parameters, airway resistance, tissue damping and tissue elastance will be measured in the patients before the CPB, immediately after CPB, and 5 min after administration of dopamine (3 mcg/kg/min).

The importance of the research is to reveal whether the beneficial mechanical changes after dopamine administrations are associated with improvements in gas exchange outcomes. Clarification of this research question have scientific relevance and may also improves patient outcomes.

Inclusion Criteria:

• Cardial surgery patients undergoing cardiopulmonary bypass procedures

Exclusion Criteria:

• Chronic respiratory diseases, elderly (>80 years)