A 50% reduction in minute ventilation was obtained in healthy mechanically ventilated swine while maintaining normocarbia using the Hemolung system [ 13].
In the chronic study phase, minute ventilation was lower for the fluoxetine trial (p <.05); however, there were no treatment affects on any of the other measurements.
Minute ventilation was similar in both modes.
Interestingly, lactate levels significantly increased when minute ventilation was increased (Table 2).
Tidal volumes were set at 6 cc/kg, and minute ventilation was similar between groups (Table 2).
At the time of the measurements, delivered inspiratory volume was 724 [597–896] ml and delivered minute ventilation was 18.6 [14.0-22.7] l/min.
In a recent retrospective study focusing on initial post-CPR mechanical ventilation settings minute ventilation was weakly correlated with the initial PaCO2 [110].
Weaning was usually decided when maximal minute ventilation was twice the minute ventilation after a 3 6 h trial of T-tube ventilation.
Minute ventilation was the same in the two static sessions and during the two exercise sessions and about five times higher during exercise compared with the static dives (p < 0.001).
Therefore, assuming that during PLR the systemic metabolic rate remained relatively constant (and minute ventilation was kept unchanged), then changes in PETCO2 should predominantly reflect variations in pulmonary blood flow and thus, indirectly, changes in CO.
Regarding the underlying model, increases in PCO2 were only minor and counterbalanced by a slight hyperventilation, as the minute ventilation was set to yield a PCO2 of 35 to 40 mmHg under baseline condition.
