Postoperative Patients in the Intensive Care Unit

Key Points

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Chest radiography is a key diagnostic test in the coronary care unit (CCU) and intensive care (ICU) unit.
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Chest radiography is a standard admission test in both venues.
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Chest radiography plays an important role in the following:
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Identifying and monitoring pulmonary parenchymal and pleural sequelae to surgery and complications of heart disease
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Identifying and monitoring the position of central venous lines and cannula, the endotracheal tube, chest drains, and pacemaker leads
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Common chest radiographic findings in patients in the CCU or ICU include the following:
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  Atelectasis
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  Pleural effusions
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  Pulmonary edema
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  Air collections
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  Diaphragmatic paralysis

Chest Radiography in the Coronary Care and Intensive Care Units

Routine Use of Chest Radiography

A chest radiograph on admission to the CCU is appropriate, if not mandatory. Subsequent radiographs are performed according to the clinical evolution of the patient and the need to monitor treatment effect.

The benefit of routine (i.e., daily, morning) chest radiography in the ICU is controversial. Several studies have described unexpectedly high detection rates of clinically unsuspected findings that have resulted in changes in management. Other studies have reported higher rates of therapeutic management, altering findings when the study was performed because of a change in a patient’s condition. More recent studies have seriously challenged the belief that routine chest radiography makes a contribution, citing that the only scenarios where important observations are made with any frequency were in patients post–Swan-Ganz insertion, in those post–endotracheal intubation, and in those with suspected new pathophysiologic slates.

Common Chest Radiographic Findings in Patients in the Coronary Care and Intensive Care Units

Atelectasis

Atelectasis is less common in the CCU setting than in the ICU setting, unless the patient is bedridden, has lung disease, is elderly, or is mechanically ventilated. The likelihood and severity of atelectasis is proportional to the amount of time the patient is in bed. The left lower lobe is most frequently affected (67% of cases) compared with the right lower lobe (about 25%) and the right upper lobe (10%). Left lower lobe atelectasis following cardiac surgery may result from (left) phrenic nerve paralysis as a result of the surgery, or from compression by the heart in the opened chest of the left lower lobe.

Atelectasis is commonly seen following surgery and may be seen in any patient in the ICU. Thoracic (especially cardiac) and upper abdominal surgery are common backgrounds for development of atelectasis. Underlying chronic lung disease, a smoking history, obesity, increasing ventilation time, and advanced age are all risk factors for the development of atelectasis. More than several days of atelectasis increases the risk of pneumonia.

The chest radiograph is much less sensitive than a computed tomography scan for the detection of atelectasis postcardiac surgery. Therefore, normal appearing lungs on chest radiography do not exclude clinically relevant atelectasis. Chest radiographic findings on atelectasis are as follows:

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Normal-appearing lung (which is the most common appearance)
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Linear/platelike/patchy infiltrates
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Lobar consolidation
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Volume loss

Pleural Effusions

Pleural effusions are commonly seen in patients with congestive heart failure, following surgical (thoracic and abdominal surgery) interventions and in the general ICU population.

Enlarging effusions suggest ongoing congestive heart failure, hemorrhage, or infection. Late-developing pleural effusions may be seen with the postpericardiotomy syndrome. Moderate and large effusions are readily appreciated on an anteroposterior or posteroanterior chest radiograph. Very small effusions (i.e., about 150 mL) are seen better by lateral decubitus radiographs than by erect or supine radiographs, and they are best detected by ultrasound or cardiac magnetic resonance imaging.

Pulmonary Edema ( Fig. 26-1 )

The portable chest radiograph may be unreliable in depicting the usual signs of pulmonary edema and distinction of cardiogenic and noncardiogenic edema is often difficult. In a supine patient, venous redistribution is normal and therefore, is not a useful sign. Portable chest radiographs are usually anteroposterior, therefore increasing the depiction of heart size and rendering assessment of true heart size more difficult.