Mechanical Ventilation

  1. General information
    1. Ventilation is performed by mechanical means in individuals who are unable to maintain normal levels of oxygen and carbon dioxide in the blood.
    2. Indicated in clients with COPD, obesity, neuromuscular disease, severe neurologic depression, thoracic trauma, ARDS; clients who have undergone thoracic or open-heart surgery are likely to be maintained on mechanical ventilation post-op.
  2. Types (positive pressure ventilators)
    1. Positive pressure-cycled ventilator: pushes air into the lungs until a predetermined pressure is reached within the tracheobronchial tree; expiration occurs by passive relaxation of the diaphragm.
    2. Volume-cycled ventilator: most popular type for intubated adults and older children; delivers air into the lungs until a certain predetermined tidal volume is reached before terminating inspiration.
    3. Time-cycled ventilator: terminates inspiration after a preset time; tidal volume is regulated by adjusting length of inspiration and flow rate of pressurized gas.
  3. Modes of mechanical ventilation
    1. Assist/control mode: client's inspiratory effort triggers ventilator, which then delivers breath; may be set to deliver breath automatically if client does not trigger it. The same tidal volume is delivered with each breath.
    2. Intermittent mandatory ventilation (IMV): client may breathe at own rate. IMV breaths are delivered under positive pressure; however, all other respirations taken by the client are delivered at ambient pressure and tidal volume is of client's own determination.
    3. Positive end expiratory pressure (PEEP): ventilator delivers additional positive pressure at the end of expiration, which maintains the alveoli in an expanded state.
    4. Continuous positive airway pressure (CPAP): achieves the same results as PEEP, except CPAP is used on adult clients who are on a T-piece.
  4. Nursing care
    1. Assess for decreased cardiac output and administer appropriate nursing care.
    2. Monitor for positive water balance. Pressure breathing may cause increase in antidiuretic hormone (ADH) and retention of water.
      1. Maintain accurate I&O.
      2. Assess daily weights.
      3. Take PCWP readings as ordered.
      4. Palpate for peripheral edema.
      5. Auscultate chest for altered breath sounds.
    3. Monitor for barotrauma (see Tension Pneumothorax).
      1. Assess ventilator settings every 4 hours.
      2. Auscultate breath sounds every 2 hours.
      3. Monitor ABGs.
      4. Perform complete pulmonary physical assessment every shift.
    4. Monitor for GI problems (stress ulcer).
    5. Administer muscle relaxants, tranquilizers, analgesics or paralyzing agents as ordered to increase client-machine synchrony by relaxing the client.