Mrs. P. is a 57-year-old woman admitted to the critical care unit after a motor vehicle crash. She sustained multiple long bone fractures and a chest contusion, and experienced an episode of hypotension in the emergency department. She received 3 units of red blood cells and 2 L of intravenous fluid in the emergency department. Within 12 hours she became short of breath with an increase in respiratory rate requiring high levels of supplemental oxygen. She was electively intubated and placed on volume-control mechanical ventilation with a positive end-expiratory pressure (PEEP) of 5 cm H2O. A continuous intravenous sedation infusion was started. The decision was made to titrate the infusion to keep her calm and comfortable. During the next 8 hours, her oxygen saturation by pulse oximetry (SpO2) steadily deteriorated, and the high-pressure alarms on the ventilator activated frequently. The nurse noted steadily rising peak airway pressures. The fraction of inspired oxygen (FiO2) had to be increased to 0.80 and the PEEP increased to 14 cm H2O to maintain her partial pressure of oxygen in arterial blood (PaO2) at 60 mm Hg. Her chest x-ray study showed bilateral infiltrates with normal heart size. A pulmonary artery catheter was inserted with an initial pulmonary artery occlusion pressure of 14 mm Hg. The sedation infusion required frequent upward titrations to maintain the desired goal of light sedation. The diagnosis of acute respiratory distress syndrome (ARDS) was made.
During the next 6 hours, Mrs. P. steadily became more hypoxemic. She was changed to pressure-controlled ventilation with a PEEP of 20 cm H2O. The FiO2
had to be increased to 1.0 (100%) to maintain a PaO2
of greater than 60 mm Hg. She was extremely restless, with tachycardia, diaphoresis, and a labile SaO2. The decision was made to start a neuromuscular blocking agent with sedation. During the next few hours her general condition continued to deteriorate. Her SaO2
ranged from 85% to 87%. Her chest x-ray findings were worse and revealed a complete whiteout. The nurses and physicians decided to turn her to the prone position in an effort to improve oxygenation. An hour after turning her to the prone position, her SpO2
began to slowly rise. After 2 hours in the prone position, her SpO2
stabilized at 93%. Slowly, the FiO2
was decreased to 0.60, with a stable SpO2
of 92%. After 18 hours she was returned to the supine position. Her SpO2
decreased to 90% and it remained stable. She was weaned off the neuromuscular blocking agent, and the sedation level was reduced to reach a goal of calm and comfortable.
Mrs. P. slowly improved over the next week. Her ventilator settings were changed from pressure-control to assist-control then to pressure support (PS). The PEEP level was decreased to a physiological level. The sedation was interrupted on a daily basis for weaning parameters and spontaneous breathing trial. On the seventh day, she was extubated and the following day transferred to the general orthopedic nursing unit on 4 liters of oxygen per nasal cannula.
Questions
1. Identify the risk factors Mrs. P. had for developing ARDS.
2. The American-European Consensus Conference recommended three criteria for diagnosing ARDS in the presence of a risk factor. List the criteria.
3. Explain the use of the high PEEP and the nursing monitoring responsibilities.
4. Explain the rationale for the use of sedation and neuromuscular blocking agents and what nursing interventions should occur when using these agents.
5. Explain the rationale for placing the patient in the prone position and what nursing interventions should occur before and after turning a patient to the prone position.