5471 MAS
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CLINICAL CASES
Recurrent lung collapse due to unidentified
phrenic nerve injury after cardiac surgery
S. S. ZAKY 1, J. SEIF 1, A. A. ABD-ELSAYED 2, C. A. BASHOUR 3
1Department
of Anesthesia, Cleveland Clinic, Cleveland, OH, USA; 2Department of Outcomes Research, Anesthesia,
Cleveland Clinic, Cleveland, OH, USA; 3Department of Cardiothoracic Anesthesia, Cleveland Clinic, Cleveland, OH,
USA
ABSTRACT
Partial or complete recurrent lung collapse after cardiac surgery is one cause of failure to wean from ventilator support,
and frequently leads to multiple reintubations and prolonging intensive care unit and hospital stays. A 79-year-old female
underwent uneventful coronary artery bypass surgery and was extubated on the first postoperative day (POD). On POD
2, a routine portable chest X-ray (CXR) revealed complete opacification of the left hemithorax. The patient was readmitted to the Cardiovascular Intensive Care Unit (CVICU) and electively intubated, and bronchoscopy revealed a
left mainstem bronchus mucous plug. The patient was extubated uneventfully the same day. A CXR on the next day
revealed recurrent total collapse of the left lung, which this time was successfully treated non-invasively with intermittent CPAP mask, percussive therapy, and respiratory treatments using acetylcysteine solution. After several days, the
left lung collapsed again, necessitating reintubation and repeat bronchoscopy. With Pulmonary medicine present, the
patient was subsequently extubated so that bronchoscopy could be performed while the patient was breathing spontaneously. This examination revealed dynamic collapse of the left lower lobe bronchus. A sniff test was performed and
revealed an immobile left hemi-diaphragm. The patient gradually became stronger, and as the airway edema subsided,
she was able to be managed on the regular nursing floor with intermittent CPAP mask treatments and mucolytics.
Although uncommon, one documented cause of failure to wean from mechanical ventilation is diaphragmatic dysfunction. This finding is often delayed because it requires a sniff test in an extubated patient to make the diagnosis.
Key words: Phrenic nerve - Thoracic surgery - Heart, surgery - Postoperative complications.
P
artial or complete recurrent lung collapse after
cardiac surgery is one cause of failure to wean
from ventilator support and usually leads to multiple reintubations. This prolongs cardiovascular
intensive care unit (CVICU) and hospital lengths
of stay, and increases the risks of airway injury and
ventilator acquired pneumonia. Common causes
of single episodes of postoperative lung collapse
include right or left mainstem bronchus intubation, atelectasis, and pneumonia.1 Less commonly, the collapse can recur either due to airway
pathology and/or diaphragmatic dysfunction.2-5
Recurrent lung collapse due to paralysis of the
diaphragm may occur because of a phrenic nerve
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injury, especially after the repair of complex congenital anomalies, or due to topical heart cooling.6-9
We describe a case of recurrent total collapse of
the left lung of a 79-year-old female after cardiac
surgery due to both dynamic airway collapse and
diaphragmatic dysfunction.
Case report
A 79-year-old female with a past medical history significant for 50 years of smoking up until one month before surgery, coronary artery disease, and hypertension underwent
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RECURRENT LUNG COLLAPSE
Figure 1.—Complete collapse of the left lung.
Figure 3.—Left main bronchus with the patient breathing spontaneously (No PEEP).
Figure 2.—CXR after bronchoscopy and pulmonary treatment.
an uneventful coronary artery bypass surgery and aortic valve
replacement for aortic valve stenosis. A mediastinal tube was
inserted in the operating room.
On the first postoperative day (POD 1), her chest x-ray
(CXR) was unremarkable and blood gases were normal. She
was transferred to the step down floor.
On POD 2, the mediastinal tube was removed. A routine
portable CXR revealed complete opacification of the left
hemithorax (Figure 1). The provisional diagnosis was collapse due to mucous plugging of the left main bronchus, given the patient’s long history of smoking. Pleural effusion was
not suspected as this usually develops slowly. A hemothorax
was also considered less likely due to the rapid change in the
CXR without significant change in the hematocrit or hemodynamic stability. A computed tomography scan of the chest
showed lung collapse without extrinsic airway compression
and no pleural effusions.
The patient was readmitted to the CVICU and elective-
2
Figure 4.—Left main bronchus after application of PPV and
PEEP of 5.
ly intubated, and bronchoscopy revealed a left mainstem
bronchus mucous plug that was removed and sent for culture and sensitivity. An immediate CXR after bronchoscopy
showed re-expansion of the left lung (Figure 2). The patient
was extubated that day uneventfully and observed in the
CVICU overnight. A CXR on the next day revealed recurrent
total collapse of the left lung, this time successfully treated
using non-invasive ventilation with intermittent CPAP mask,
percussive therapy, and respiratory treatments using acetylcysteine solution.
After several days, however, the left lung again collapsed,
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RECURRENT LUNG COLLAPSE
ZAKY
the patient was reintubated, and repeat bronchoscopy was
performed to reexpand the lung. Due to the recurrent
nature of the left lung collapse with no extrinsic compression and no episodes of collapse of the right lung, intrinsic pathology of the left lung was at this point thought to
be more likely. Pulmonary medicine was consulted and the
patient was subsequently extubated so that awake bronchoscopy could be performed with the patient breathing
spontaneously. This examination revealed dynamic collapse of the left lower lobe bronchus (Figures 3, 4). This
finding, together with the postoperative course of the
patient, suggested the diagnosis of left diaphragmatic paralysis secondary to phrenic nerve palsy after the surgery. A fluoroscopic sniff test was performed with the patient extubated, revealing an immobile left hemi-diaphragm. The patient
gradually became stronger and as the airway edema subsided, she could be managed on the regular nursing floor
with intermittent CPAP mask treatments and mucolytics.
The patient was eventually discharged home on postoperative day 27 in stable condition. The patient had outpatient follow-up at six months with stable respiratory function at that time.
the airway caused by paralysis of the diaphragm
on the same side. In this case, the bronchus to the
left lower lobe could be seen collapsing while the
patient breathed spontaneously. The collapse could
be due to an intrinsic abnormality in the airway
secondary to her long-standing bronchitis and tissue edema, and then made worse by diaphragmatic dysfunction. This leads to the generation of
increased negative pressure on the opposite side,
which rapidly sucks air out of the affected lung
collapsing the ipsilateral airway. Due to recurrent
narrowing of the airway with each breath, a
mucous plug can form that then leads to lung collapse.
As in this case, the patient must be supported
with aggressive respiratory therapy that includes
mucolytics, CPAP mask, and percussive therapy
until they become strong enough to match the
increased work of breathing required to overcome
the deficit.11, 12
Discussion
Although uncommon, one cause of failure to
wean from mechanical ventilation after cardiac
surgery is diaphragmatic dysfunction.3 The diagnosis is often delayed because it happens infrequently and the diagnostic fluoroscopic sniff test
usually requires a patient to be extubated as positive pressure ventilation can potentially obscure the
x-ray.
Postoperative lung collapse after surgery is
frequently due to mucous plugging, but must
be differentiated from a hemothorax, which has
a similar appearance.10 Distinguishing features
of collapse versus hemothorax typically include
an “overnight” change in the CXR with lung
collapse in a patient without significant change
in the hemodynamic status or hematocrit. The
volume require for a hemothorax to give the
same appearance as a collapsed lung is over two
liters in an adult, and should be associated with
changes in either the hemodynamics or the
hematocrit. If a pleural effusion is suspected,
chest ultrasound can make the diagnosis. In this
case, collapse was considered more likely and
thus chest CT was more useful as an initial
study.
Awake bronchoscopy is a valuable tool in this situation, as it can demonstrate dynamic collapse of
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Conclusions
Although uncommon, one documented cause
of failure to wean from mechanical ventilation is
diaphragmatic dysfunction. This finding is often
delayed because the diagnosis requires a sniff test
in an extubated patient.
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Received on December 5, 2008 - Accepted for publication on March 05, 2009.
Corresponding author: A. A. Abd-Elsayed, MD, MPH, Outcomes Research Department, 9500 Euclid Avenue/P77, Cleveland, OH 44195,
USA. E-mail: Abd-ela@ccf.org
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