Low minute volume

The minute ventilation (MV) is the product of respiratory rate (RR) x tidal volume (V_T).  This alarm needs to be set up carefully when the baby is first ventilated.  The easiest way is to go the alarm screen and press the "+/- 30%" button - this then sets the alarm settings 30% above and below the current MV.

However, MV can change, particularly if the baby's respiratory effort is changing or if there is a variable leak affecting the measured expired V_T.  Most commonly, this is when the baby is breathing well and having each breath assisted (as in PSV), then has a pause.  Clearly, if the RR halves and the V_T remains the same, then MV halves also.

There is no safe and easy way around this alarm.  The easy way, of course, is to set the lower alarm limit at zero and the upper alarm limit at something unachievable, but this is not safe.  For babies with large leaks, however, it may be necessary to set the lower limit to zero.

Again, the key is to think about why the MV has changed, and whether this reflects a problem with measurement (leak), respiratory effort (respiratory rate/apnoea), or a change in compliance (with V_T changing for the same pressure measurements).