29 If the degree of CO2 retention is sufficiently great to cause a marked decrease in the patient’s pH (<7.25–7.30), ventilatory assistance with a mechanical ventilator is often necessary.* Similarly, if marked CO2 retention has impaired the patient’s mental status, ventilatory assistance is indicated. For the patient who has a good chance of rapid reversal of CO2 retention with therapy (assuming the level of CO2 retention is not life threatening), this therapy is often attempted first, with the hope of avoiding mechanical ventilation. However, patients with chronic hypercapnia may be subject to further increases in PCO2 when they receive supplemental O2 (see Chapter 18). If PCO2 rises to an unacceptably high range, the patient may require intubation and assisted ventilation with a mechanical ventilator to maintain an acceptable PCO2. Fortunately, this complication is infrequent with judicious use of supplemental O2.
Management of Respiratory Failure
Goals of Supportive Therapy for Gas Exchange
Maintenance of Carbon Dioxide Elimination
Maintenance of Oxygenation