The Science Journal of the American Association for Respiratory Care

Test Your Radiologic Skill

January 2002 / Volume 47 / Number 1 / Page 91

Sudden Development of Right and Left Lung Asymmetry in a Pediatric Patient Following Craniotomy

Kathleen Deakins RRT and Robert L Chatburn RRT FAARC

A 7-year-old girl presented to the pediatric intensive care unit following a craniotomy that left her with dysphagia, poor cough, and problems with retained secretions. Pulmonary function and blood oxygen saturation worsened for 3 days after surgery. Noninvasive positive-pressure ventilation and increased fraction of inspired oxygen improved oxygenation. Glycopyrrolate was administered to decrease secretions but had little effect. The first chest radiograph showed left lung hyperinflation. The right lung showed loss of volume and elevation of the right hemidiaphragm. There was no mediastinal shift. Another chest radiograph 3 hours later showed substantial improvement. We discuss the causes of acute lung volume asymmetry and possible interpretations of the radiographs.
Key words: lung asymmetry, pediatric, glycopyrrolate.
[Respir Care 2002;47(1):69-90]


A 7-year-old girl presented to the pediatric intensive care unit postoperatively following a retromastoid craniotomy for resection of a malignant ependymoma of the fourth ventricle. This was the fourth surgery for resection of this tumor, which was diagnosed by MRI. The patient was extubated on arrival to the pediatric intensive care unit. Cranial nerve dysfunction from the surgery resulted in oral-motor difficulties, including dysphagia, inability to mobilize secretions, muscle weakness, and ineffective cough. These complications resulted in re-intubation on postoperative day 2. Following a short-term regimen of intravenous glycopyrrolate (instituted in an attempt to decrease the excessive volume of secretions), the patient was again extubated on day 3. Subsequent oral and nasotracheal suctioning was required every 30-60 minutes for copious, viscous (nonpurulent) secretions.

Over the next 12 hours, the patient required an increase in fraction of inspired oxygen, from 35% to 50%, and it was difficult to maintain oxygen saturation \g 85%. Tachypnea, nasal flaring, shallow respirations, and muscle weakness developed, and impending respiratory failure was apparent. Noninvasive ventilation was instituted with bi-level positive airway pressure at an inspiratory pressure of 16 cm H2O, an expiratory pressure of 8 cm H2O, and a 5 L/min oxygen bleed-in. Oxygen saturation improved to 92%. That evening the patient was changed to supplemental oxygen by mask. Suctioning requirements again increased to every 30 minutes throughout the night. Seventeen hours following extubation, a chest radiograph (Fig. 1) was obtained to evaluate the presence of infiltrate or atelectasis.

The patient was maintained on supplemental oxygen by mask, and oxygen saturation continued to improve, to 95%, without any further increase in oxygen requirement. A second chest radiograph (Fig. 2) was obtained 3 hours later. Compare Figure 1 and Figure 2.


  1. What is the most obvious change?
  2. What can account for the dramatic change in the chest radiograph in Figure 2?


Figure 1 reveals asymmetry of the right and left lungs, with hyperinflation of the left lung, loss of right lung volume, and elevation of the right hemidiaphragm, but without mediastinal shift. Normally, lung volumes can be evaluated by observing the presence of lung tissue extending out to the periphery and diaphragmatic excursion extending to the level of the 9th to 11th ribs posteriorly.1 The left hemidiaphragm is normally located lower than the right because the presence of the liver in the right upper quadrant of the abdomen elevates the right hemidiaphragm slightly. Acute discrepancy in the lung volumes, as seen in Figure 1, is a cause for concern. Decreased lung volumes may be attributed to the presence of retained secretions resulting from ineffective cough, immobility, or shallow inspiration commonly seen in postoperative patients.2 Decreased lung volumes accompanied by opacities illustrate the presence of atelectasis. Decreased lung volumes and elevation of the diaphragm on the affected side, with mediastinal shift toward the opacity, may indicate atelectasis caused by bronchial obstruction.3

Fig 1
Fig. 1. Chest radiograph 17 hours after extubation.

Fig 2
Fig. 2. Chest radiograph 20 hours after extubation.

Increased lung volumes caused by sudden expansion of one lung may result from pleural effusion, which may present with air bronchograms if the underlying lung is atelectatic.3 In Figure 1, ball-valve obstruction or pleural effusion are unlikely, since there is no mediastinal shift in either direction, nor air bronchograms in the left lung.

In Figure 2 the left and right hemidiaphragms are at the same level. The most obvious change is the prompt and complete resolution of the disparity of lung sizes. Evaluation of diaphragm paralysis should have been considered in the chest radiograph interpretation, based on the patient's recent history of craniotomy and the lung asymmetry seen in Figure 1. Phrenic nerve palsy should be suspected if the affected diaphragm is elevated, mediastinal shift occurs during inspiration, and paradoxical diaphragmatic movement of the affected diaphragm is noted on inspiration during a forced expiratory maneuver or sniffing. The “sniff test” is done under fluoroscopy.4 This patient was not evaluated in this manner because of limitations of head positioning and inability to cooperate and follow commands.

The most likely explanation for the disparity of lung volumes between Figures 1 and 2, in the absence of mediastinal shift, is transient atelectasis of the right lung. The history of dysphagia, inability to handle secretions, ineffective cough, and muscle weakness support this diagnosis. Airway clearance techniques were indicated to mobilize and facilitate the removal of secretions. It seems less likely that there was transient paralysis of the right diaphragm due to phrenic nerve injury or other damage during surgery, because the lung volumes returned to normal within 3 hours.

Initial interventions used in an attempt to assist in the removal of secretions included nasotracheal suctioning and glycopyrrolate. Frequent stimulation of the bronchi, larynx, or pharynx can result in stimulation of the cough reflex.5 Repeated irritation caused by frequent suctioning puts the patient at risk for complications such as bleeding, bronchospasm, and irritation of the soft tissues, resulting in swelling, nosocomial pneumonia, increased intracranial pressure, and exacerbation of cerebral edema, which were relevant to this case.5 Glycopyrrolate was used to control the volume of secretions, but with little effect in this case. The Vest Airway Clearance System (Advanced Respiratory, St Paul, Minnesota) was used to enhance airway clearance following the chest radiographs.

The patient required reintubation the following day. Tracheostomy and gastric feeding tube were later performed to facilitate long-term needs for airway clearance and feeding.


  1. Rau J, Pearce D. Understanding chest radiographs. Denver: Multi-Media Publishing; 1984:36-38.
  2. Henry DA. Chest imaging in the neurosciences intensive care unit. Respir Care 1999;44(9):1064-1077.
  3. MacMahon H. Pitfalls in chest radiology. Respir Care 1999;44(9):1018-1032.
  4. Beers MH, Berkow R, editors. The Merck manual of diagnosis and therapy, 17th ed. Whitehouse NJ: Merck; 1999;6:64.
  5. AARC Clinical Practice Guideline: Nasotracheal suctioning. Respir Care 1992;37(8):898-901.

Kathleen Deakins RRT and Robert L Chatburn RRT FAARC are affiliated with Rainbow Babies and Children's Hospital of University Hospitals of Cleveland, Cleveland, Ohio.

Correspondence: Robert L Chatburn RRT FAARC, Department of Respiratory Care; University Hospitals of Cleveland, 11100 Euclid Avenue, Cleveland OH 44114. E-mail:

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