Lewis: Medical-Surgical Nursing, 7th Edition
Answer Guidelines for Case Studies in Textbook
Chapter 66: Nursing Management: Critical Care
Critical Care and Mechanical Ventilation
1. Because Mr. R. is unconscious with no response to painful stimuli, he requires an artificial
airway to decrease the risk of aspiration due to the lack of airway protection reflexes and to
facilitate secretion removal because he cannot effectively clear his airway. The endotracheal
tube is used as the artificial airway of choice at this time and it provides a closed system for
mechanical ventilation during this acute illness.
2. Mr. R.’s ABGs primarily indicate respiratory alkalosis. The pH is above 7.45 and the PaCO2
is below 35 mm Hg, indicating he is blowing off too much carbon dioxide. However, his
bicarbonate level is increased above 30 mEq/L, indicating that he has retained bicarbonate
and has a metabolic alkalosis as well. The most common cause of this situation is
overventilation of a patient who normally has chronic alveolar hypoventilation with chronic
CO2 retention and compensatory bicarbonate retention by the kidneys. These findings indicate
that Mr. R. has chronic obstructive lung disease. To prevent the development of hypokalemia,
hypocalcemia, neuromuscular irritability, seizures, or death that occur with the abrupt onset
of alkalosis in a patient who has normally compensated respiratory acidosis, it is important to
reduce the tidal volume and ventilatory rate of the ventilator so that more carbon dioxide is
retained. Ventilated patients with COPD also do better with a short inspiratory and longer
expiratory time that is characteristic of their normal respiratory patterns. Currently Mr. R.’s
PaO2 level is high for a patient with COPD, but he needs immediate attention to correct the
respiratory and metabolic alkalosis.
3. Mr. R’s PaO2/FIO2 (94/0.6) ratio is 157. A normal PaO2/FIO2 ratio is 350 to 400, and
mechanical ventilation is indicated when the ratio is <200. Weaning from the ventilator is not
feasible until the ratio is >300. These values signify that even with a FIO2 of 0.6 (60%), Mr.
R.’s lungs have limited ability to oxygenate arterial blood.
4. Mr. R. requires hemodynamic monitoring to guide further fluid and drug therapy. He is
tachycardic and hypotensive. The PA diastolic pressure and the PAWP will provide
information on Mr. R.’s fluid volume status and cardiac function. Two major nursing
considerations for a patient with a PA catheter include (1) collecting baseline and ongoing
data from many sources (e.g., physical examination of the patient, hemodynamic parameters,
laboratory values) to evaluate the effectiveness of interventions, and (2) observing the patient
for signs of complications related to the PA catheter (e.g., infection, air embolus).
5. Mr. R.’s PAWP is high, his CI is low, and his SVR is high. These values indicate heart
failure, most likely from the dysrhythmia. Medical interventions would be aimed at treating
the heart failure and could include initiation of drug therapy (e.g., dobutamine, digoxin),
cardioversion to convert Mr. R.’s rhythm to normal sinus, and placement of an intraaortic
balloon pump to provide temporary circulatory assistance should his condition worsen.
6. PPV affects circulation because of the transmission of increased mean airway pressures to the
thoracic cavity. The increased intrathoracic pressure compresses thoracic vessels and
consequently decreases venous return (preload) and CO. Mean airway pressure is further
increased if PEEP is added to improve oxygenation. Generally, PEEP is contraindicated or
used with extreme caution in patients with highly compliant lungs as occurs in the patient
with COPD. Assuming that Mr. R.’s heart failure is corrected, the addition of PEEP may
place him at risk for a subsequent reduction in CO/CI and/or barotrauma secondary to PEEP.
7. Nursing diagnoses: ineffective airway clearance, decreased cardiac output Collaborative
problems: barotrauma, sepsis
The nurse would coordinate the meeting by assuring that key family and health care team
members (e.g., physicians, clergy) were in attendance. In addition, the nurse would contribute to
the meeting by serving as an advocate for the patient and family members