新生儿机械通气和安全氧疗讲解课件.pptVIP

Note that if the inspiratory flow is insufficient, the loop bends inward. * * On the other hand, if the transition from exhalation to inspiration occurs without the expiratory flow returning to zero, you have Auto-PEEP present. * Air Trapping Flow graphic most helpful End Expiration and End Expiratory Flow Rate keys to identifying air trapping End Expiratory Flow does NOT return to baseline To correct for air trapping increase expiratory time (Increase total cycle time, Decrease inspiratory time, Lower delivered tidal volume- Peak Pressure in Pressure Control and set tidal volume in Volume Control) * When the inspiration criteria are met, exhalation begins as pictured in yellow here. Normally, this curve resembles a football. * Overdistention is caused by a combination of PEEP and too much volume or pressure. A is the peak inspiratory pressure; B is the upper inflection point; C is the lower inflection point. The lower inflection point identifies the level of PEEP where the lung is more compliant. This is also referred to as critical opening pressure. The upper inflection point indicates where the lung becomes less compliant and illustrates where overdistension starts to occur. Decreasing the volume or pressure may help avoid barotrauma in this situation. * Using both the volume- and flow-time curves provides insight to set the appropriate PIP and I-Time in PCV. For example, the physician orders PCV and tells you that he wants a VT of 500 cc. PCV is initiated with a PIP of 20 cm, resulting in a VT of 450 cc. Before increasing the inspiratory pressure to obtain additional VT, maximize inspiratory time. As shown here at the arrow, inspiratory flow does not return to zero before cycling into expiration. This could result in a lesser delivered volume. * Pictured in blue here is potentially lost VT. Increasing inspiratory time to allow the flow to return to baseline may increase VT without increasing PIP. * * Mandatory Breath Expiration 0 20 40 60 20 40