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Minute volume

 - product of respiratory Rate and tidal volume
- note: oxygenation is Independent of minute volume until ventilation is very low. hence: increasing minute volume does not improve oxygenation; 
- note: CO2 removal is directly dependent on minute volume. 
- pCO2 should be maintained at 40 mm or less; 
- w/ Met. acidosis: consider: 
- hypoperfusion, hypovolemia, or sepsis 
- w/ Resp. Acidosis: consider: 
- dislodge tube, leak, vent malf(x), Pneumo, Atelectasis 
- mild Resp Alk is well tolerated. 
- w/ apnea pCO2 rises 3 mm/min, so that maintenance of mild resp alkalosis provides extra minutes during episodes of ventilator malfunction; 
- if CO2 is too high, Minute volume must be increased; 
- either increase Tidal vol. or Rate
- w/ High pCO2: must increase Minute Vol; (always ensure that ventilator is functioning properly, esp check for a leak around the cuff of the endotracheal tube or in the ventilatory tube, or connections, or if the endotracheal tube has become dislodged 
- (Check Breath sounds / chest expansion) 
- if tidal volume is already at the upper limits of suggested range, or if peak inspiratory pressures are high ( > 50), or if there is prominent chest expansion w/ each breath, one would be inclined to increase Rate rather than volume. 
- if the rate is already at the upper limits of range, or if peak inspiratory pressures are low, and if chest expansion w/ each breath is not marked, tidal volume may be safely increased. 
- w/ Low pCO2: must decrease Minute Vol 
- note: mild respiratory alkalosis is desirable, and usually minute ventilation is not decrease unless pCO2 < 30 mm Hg) 
- decr min. volume may occur by decr Rate or tidal volume
- however, a illogical method is by increasing the length of ventilator tubing