Inspiratory time

[yalsaba]

Hi

I want your experience in adjusting inspiratory time in SIPPV mode

Thanks

[Padkaer]

That very much depends on the type of ventilator you are using, and on whether it offers volume guarantee/limitation or not.

Very shortly summarized your inspiratory time should be long enough for the child to have a small plateau period during inspiration, and in a not to sick babylung an i-time somewhere between 0.35 s and 0.42 s probably won`t be to far of the mark.

A somewhat longer answer could be : To my knowledge ventilators injures the lung in 4 ways (worst first)

1) Volume

2) Pressure

3) Oxygen

4) Atelectasis

Ventilator strategy should aim at reducing all 4. Worst first.

The amount of volume given by a ventilator is a function of your delta-pressure ( peak minus peep), the inspiratory time and the compliance of the lung your ventilating. So (not going into the whole open-lung strategy) given that you want to reach an ordinary tidalvolume of 4-6 ml/kg you have two ways of doing this - going up on the delta-pressure or the inspiratory time. Going with too low inspiratory times (with out adequate plateau) will cause you to use excessive high delta-pressure which will damage the lung. Using to long i-times with fixed delta-pressure, and no volume limitation/guarantee on the ventilator, will cause to high tidal volumes and injure the lung even worse.

Generally, a ventilator with a volume limitation/guarantee mode that ensures your tidal volumes and delta-pressures are kept down as the lungs compliance betters (especially when treating IRDS, where this can happen quite quickly) is IMHO recommendable - as long as it is not used as an autopilot. A ventilator in volume guarantee mode should never ever be set with max possible pressures more than 3-4 mBar above, what is needed for the child to reach adequate tidal volumes at any given time.

Kind regards

Jesper