Human versus Computer Controlled Selection of Ventilator Settings: An Evaluation of Adaptive Support Ventilation and Mid-Frequency Ventilation

Table 1

Clinical scenarios.

Clinical Scenario	Acid-base and oxygenation status	Compliance mL/cm H2O	Resistance; cm H2O/L/S
Healthy patient undergoes surgical repair of the knee. He has a rare enzymatic defect that prolonged the paralytic half-life and will require mechanical ventilation until paralysis wears off.	Normal acid-base status. ABG: pH 7.40, PaCO2 40, HCO3 of 24, and PaO2 90 on a 30% FiO2	66	4
ARDS due to severe sepsis. Current ventilation: VC-CMV, VT 550, RR 28, FiO2 65%, PEEP of 12.	Metabolic and respiratory acidosis. ABG: pH 7.25, PaCO2 42, HCO3 of 18 and PaO2 65 on a 65% FiO2	25	10
Morbid obesity: weight is 200 kg, he has opiate overdose. He is paralyzed due to high ventilator pressures. Current ventilation: VC-CMV, VT 650, RR 18, FiO2 35%, PEEP of 8.	Respiratory acidosis. ABG: pH 7.27, PaCO2 85, HCO3 of 38 and PaO2 65 on a 35% FiO2.	35	12
COPD: has a broken hip, intubated for surgery. Current ventilation: VC-CMV, VT 700, RR 12, FiO2 35%, PEEP of 8, and I : E 1 : 4.	Respiratory alkalosis. ABG: pH 7.53, PaCO2 42, HCO3 of 34 and PaO2 65. No auto PEEP is detected.	60	16
Status asthmaticus: paralyzed in the ED to facilitate ventilation. Current ventilation: VC-CMV, VT 600, RR 22, FiO2 35%, PEEP of 10, I : E is 1 : 2.	Severe respiratory acidosis. ABG: pH 7.12, PaCO2 75, HCO3 of 24 and PaO2 65 on a 35% FiO2. Auto PEEP is 6.	80	Inspiratory 16; Expiratory 22

VC-CMV: Volume control-continuous mandatory ventilation, V_T: tidal volume, RR: respiratory rate (breaths per minute), I : E: inspiratory : expiratory ratio, PEEP: positive end expiratory pressure (cm H₂O), ABG: arterial blood gas. PaCO₂: arterial partial pressure of CO₂ (mmHg), PaO₂: arterial partial pressure of O₂ (mmHg), FiO₂: inspired fraction O₂. References: healthy paralyzed [14], ARDS [15, 16], morbid obesity [14], COPD [15], status asthmaticus [17].