624074/07 D-7
D.7 Control settings
CAUTION
• When ventilating with a mask, avoid high
airway pressures. High pressures may cause
gastric distension.
• Peak pressures exceeding 33 cmH2O may
increase the risk of aspiration due to gastric
insufflation
1
. When ventilating with such
pressures, consider using an invasive mode.
When a significant leak occurs, the inspiratory flow can never
fall below ETS, thus not allowing the ventilator to cycle into
exhalation, and resulting in endless inspiration. For this reason,
the TI max setting was added, providing an alternative way to
cycle into exhalation. When inspiration lasts longer than
TI max, the ventilator cycles into exhalation.
When the ventilator cycles are based on the ETS setting rather
than TI max, it is the most comfortable for the patient. Ensure
the TI max setting is sufficiently long to give ETS the chance to
cycle the ventilator. Adjusting the TI max setting increases or
decreases the allowable inspiratory time. Increasing ETS above
the default 25% allows the ventilator to cycle to terminate
inspiration at a higher flow, to accommodate larger leaks.
Other controls require special attention. Carefully observe the
patient/ventilator interaction. The leakage in this mode reduces
the actual applied PEEP/CPAP and give rise to autotriggering.
Adjust Psupport or Pinsp to obtain appropriate tidal volumes.
Adjust PEEP/CPAP further, considering oxygenation and
AutoPEEP.
1. Bach JR, Alba AS, Saporito LR. Intermittent positive pressure ventilation
via the mouth as an alternative to tracheostomy for 257 ventilator users.
Chest 1993;103:174-182.
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