A patient receiving mechanical ventilation has an exhaled tidal ...

[dalyningkenk]

A patient receiving mechanical ventilation has an exhaled tidal volume (VT) of 500 mL and a positive end expiratory pressure setting (PEEP) of 5 cm H2O. Patient-ventilator system checks reveal the following data:
 
  Time PIP (cm H2O) Pplateau (cm H2O)
  0600 27 15
  0800 29 15
  1000 36 13
 
  The respiratory therapist should recommend which of the following for this patient?
  1. Tracheobronchial suctioning
  2. Increase in the set tidal volume
  3. Beta adrenergic bronchodilator therapy
  4. Increase positive end expiratory pressure
  a. 1 and 3 only
  b. 2 and 4 only
  c. 1, 2, and 3 only
  d. 2, 3, and 4 only

Question 2

Plateau pressure (Pplateau) is measured during which phase of the ventilatory cycle?
 
  a. Inspiration
  b. End-inspiration
  c. Expiration
  d. End-expiration

[EAN94]

Answer to Question 1

ANS: A
Calculate the transairway pressure (PTA) by subtracting the plateau pressure from the peak inspir-atory pressure. Analyzing the PTA will show any changes in the pressure needed to overcome air-way resistance. Analyzing the Pplateau will demonstrate any changes in compliance. The Pplateau re-mained the same for the first two checks and then actually dropped at the 1000-hour check. An-alyzing the PTA, however, shows a slight increase between 0600 and 0800 (from 12 to 14 cm H2O) and then a sharp increase to 23 cm H2O at 1000. Increases in PTA signify increases in airway resistance. Airway resistance may be caused by secretion buildup, bronchospasm, mucosal ede-ma, and mucosal inflammation. Tracheobronchial suctioning will remove any secretion buildup, and a beta adrenergic bronchodilator will reverse bronchospasm. Increasing the tidal volume will add to the airway resistance according to Poiseuille's law. Increasing the PEEP will not address the root of this patient's problem; the patient's compliance is normal.

Answer to Question 2

ANS: B
The calculation of compliance requires the measurement of the plateau pressure. This pressure measurement is made during no-flow conditions. The airway pressure (Paw) is measured at end-inspiration. The inspiratory pressure is taken when the pressure reaches its maximum during a delivered mechanical breath. The pressure that occurs during expiration is a dynamic measure-ment and drops during expiration. The pressure reading at end-expiration is the baseline pressure; this reading is either at zero (atmospheric pressure) or at above atmospheric pressure (PEEP).

[dalyningkenk]

TYSM

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Excellent