all of the pedi vents on my caseload are on peep(s) of 4-6 with uncuffed trachs...it really does help keep their po2 levels up...my understanding from the pedi pulmos is that while they do end up a 0 peep delays their getting there...keeping in mind that these kids are also on pressure support and/or simv. below is an excerpt that discusses/describes peep really well...i have based much of the vent class i teach on information from the website listed.
positive end-expiratory pressure
for most ventilated patients, the machine delivered fraction of inspired oxygen ( fio2) will provide an adequate pao2. when this fio2 is above 0.60 and the pao2 remains inadequate, positive end-expiratory pressure (peep) is often employed. peep is used only to improve the pao2, not the paco2. peep is an alteration of ventilator pressures so that airway pressure is positive (above atmospheric) throughout the breathing cycle. it may be used with any of the ventilatory modes discussed so far.
peep was first introduced into clinical medicine in 1967 when physicians working in a denver intensive care unit described their experience with adult respiratory distress syndrome (ards) patients (ashbaugh, bigelow, petty, et al., 1967). two of the patients received peep on an empiric basis, and their pao2 improved. peep has since been used routinely in the management of ards. a pressure curve for peep is shown in fig. 10-6. normally, airway pressure at endexpiration is atmospheric (measured at the mouth); with peep it is above atmospheric. as commonly employed, peep pressures are usually between 5 and 20 cm h2o above atmospheric pressure.
the mechanism by which peep improves oxygenation is not known for sure. since peep increases functional residual capacity, it probably leads to better oxygenation by preventing end-expiratory collapse (fig. 109). (lung water studies have shown that peep does not diminish total lung water, but just redistributes it within the alveoli. therefore peep cannot be considered a primary treatment for pulmonary edema.)
it is important to recognize that peep is measured in the upper airways and does not equal airway pressure in the alveolus. the peep is considerably dissipated by the time it reaches the alveoli. yet it is the positive pressure at the alveolar level that both improves oxygenation and leads to complications. there is no practical way to know how much of the measured peep is present in the alveoli; the amount of dissipation depends on complex factors, including lung compliance and airways resistance. nonetheless, as learned by experience and observation, a peep of less than 10 cm h2o usually improves pao2 without significant complications; above this level, peep is more likely to be accompanied by complications, either barotrauma or a decrease in cardiac output (discussed later in this chapter).
the high and low pressue settings you list are pretty freaky (to me) to see in a kido...what is this childs age and dx? is s/he vent dependant?