Ventilators

Positive Pressure Ventilation:
** pressure control: patient gets breath at set pressure but TV is variable. Used in neonatology, disadvantage w/ increased compliance, the TV could elevate enough to cause a pneumothorax
** Volume Controlled: TV is set, machine will use whatever pressure needed to give that volume of breath. But remember, with decreased compliance, the pressure could cause barotraumas

1) CMV (controlled mandatory ventilation)
- keep patient sedated
- patient gets breaths at a set rate, patient is sedated and muscle relaxed (cannot initiate breath on own)

2) IMV (intermittent mandatory ventilation)
- keep patient sedated
- patient gets breaths at a set rate but can also take own breaths
- the machine may give patient breath immediately after own breath = pneumothorax

3) SIMV  ( synchronized intermittent mandatory ventilation)
- ventilator synchronizes delivered breaths w/ inspiratory effort, allows patient to finish breaths

4) ACV (assist controlled ventilation)
- not used much in pediatrics
- if patients rate insufficient, machine will provide breath even when not triggered

CPAP ( continuous positive airway pressure)
- no ventilated breaths given, but air flow is such that a give pressure is maintained throughout the respiratory cycle
- helps to stent airways, maintain chest walls in babies, maintain certain functional residual capacity
- maintains lungs compliance
- same as PEEP concept (but not on ventilator)
- can be administered via endotracheal tube (while weaning ventilator in preparation for extubation), face mask, or nasal prongs

BIPAP
- like CPAP, except more positive pressure given during inspiration
- given by mask when trying to avoid intubating a child
- helps obese kids by giving pressure boost to help overcome heavy chest while sleeping (OSA)
- set inspiratory and expiratory pressure (babies-10/5, older child- 12/6)

Setting the Ventilator:

1) Tidal volume (normal= 5-7 ml/kg): start at 10 ml/kg (secondary to tubing/dead air space); give enough for chest rise (expect PIP of 20-25 with mild lung disease)
2) Rate: baby – 25-30 bpm, toddler -15-20, child – 12-18, teen – 8-12
3) FiO2: start at 100% oxygen and work down(get to 60%to avoid O2 toxicity)
4) PEEP: set at 3-5 (normal person generates2-3 cc H2O pressure at glottis during exhalation, but ETT bypasses this mechanism)
5) Inspiratory time (I-time): rate determines cycle length, and this then determines how much of the cycle is spent on inspiration (SIMV of 20 bpm means each breathing cycle lasts 3 sec; I- time of 0.6 sec means 2.4 sec are allotted for expiration)
6) Pressure support; a set positive pressure applied to circuit once patient initiate the breath that augments the breath, helps overcome resistance in tubing/machine