Mechanical Ventilation & Oxygenation
Every mechanical ventilation & oxygenation calculator on CalcEngines — unit converters, derived indices and interpretive tools, each with its formula, a worked example and the reference intervals it is judged against.
8 calculators in this section
- Dead Space Fraction Calculator (Bohr and Enghoff)Bohr's equation uses MEAN ALVEOLAR CO₂; Enghoff substituted arterial CO₂ and thereby folded shunt and V/Q mismatch into the answer. The Enghoff value is systematically larger, and most bedside calculations labelled Bohr are Enghoff.
- Driving Pressure CalculatorDriving pressure is plateau pressure minus TOTAL PEEP — the tidal pressure swing across the respiratory system, and the variable that carried the mortality signal in Amato's analysis of nine ARDS trials.
- Mechanical Power CalculatorMechanical power is the energy the ventilator puts into the respiratory system each minute, in joules per minute. The published simplified forms for volume control and pressure control are NOT interchangeable, so this page computes both.
- Oxygenation Index and OSI CalculatorThe oxygenation index and the oxygen saturation index use MEAN AIRWAY PRESSURE, not PEEP, which is what separates them from the P/F ratio. Both are the oxygenation criterion of the paediatric ARDS definition.
- Rapid Shallow Breathing Index (f/VT) CalculatorRespiratory rate divided by tidal volume in litres, during a spontaneous breathing trial. Yang and Tobin's threshold of 105 came from 100 medical ICU patients in 1991, and its discrimination in later work is considerably worse.
- ROX Index CalculatorThe ROX index is SpO₂/FiO₂ divided by respiratory rate, for patients on high-flow nasal oxygen. Its threshold is not one number: it depends on the hours of high-flow elapsed, and it was derived in pneumonia.
- Static and Dynamic Compliance CalculatorStatic compliance uses the inspiratory-hold plateau and measures the respiratory system itself. Dynamic compliance uses the peak pressure and carries airway resistance inside it. The gap between them is the clinical point.
- Ventilatory Ratio CalculatorVentilatory ratio compares the minute ventilation and PaCO₂ a patient actually has with the values predicted for their predicted body weight. It is a dead-space surrogate needing no capnography — and a surrogate is what it is.