Reaction of INTELLiVENT-ASV to metabolic acidosis

Article

Author: Matthias Himmelstoss

Date of first publication: 24.10.2016

Last change: 16.12.2016

Acidosis will shift the dissociation curve to the right.

Metabolic acidosis is defined as pH <7.35 and base excess < -2 mmol/l, with standard bicarbonate < 21 mval/l in blood gas analysis. It results from an increase of acids in the blood or a loss of bicarbonate buffers.

Reaction of INTELLiVENT-ASV to metabolic acidosis

Effect in passive patients

In passive patients with metabolic acidosis, mechanical ventilation will not change because PetCO2 is not affected. In terms of oxygenation, acidosis will shift the dissociation curve to the right. This shift will cause a slight decrease in SpO2, which may induce an increase in FiO2 or PEEP. However, this effect will be very small.

Effect in spontaneously breathing patients

If the patient is breathing spontaneously, metabolic acidosis will increase the respiratory drive and lead to a higher respiratory rate (RR). If the respiratory rate is above the upper limit for the RR target zone, INTELLiVENT-ASV will react by increasing the %MinVol. If the tidal volume is below target, INTELLiVENT-ASV will also increase the pressure support (Pinsp). The consequence will be hypocapnia in order to correct pH.

INTELLiVENT-ASV therefore reacts accordingly to support the additional work of breathing by increasing pressure support only if needed. Oxygenation remains the same in both spontaneously and passively breathing patients.