(Chest. 2006;130:575-577.)
© 2006
American College of Chest Physicians
Intrapulmonary Bronchogenic Cyst and Cerebral Gas Embolism in an Aircraft Flight Passenger*
Francisco Aécio Almeida, MD;
Bryan X. DeSouza, MD;
Thomas Meyer, MD, FCCP;
Susan Gregory, MD, FCCP and
Lee Greenspon, MD, FCCP
* From the Division of Critical Care, Pulmonary, Allergic, and Immunologic Diseases (Dr. Almeida), Thomas Jefferson University Hospital, Philadelphia; and the Divisions of Neurology (Dr. DeSouza), and Pulmonary Diseases and Critical Care (Drs. Meyer, Gregory, and Greenspon), Lankenau Hospital, Wynnewood, PA.
Correspondence to: Francisco Aécio Almeida, MD, Division of Critical Care, Pulmonary, Allergic, and Immunologic Diseases, Thomas Jefferson University Hospital, 834 Walnut St, Suite 650, Philadelphia, PA 19107; e-mail: francisco.almeida{at}jefferson.edu
 |
Abstract
|
|---|
Although it is estimated that > 1 billion passengers travel by air worldwide each year, the incidence of in-flight emergencies is low. However, due to nonstandardized reporting requirements for in-flight medical emergencies, the true incidence of pulmonary barotrauma in airplane passengers is unknown. We describe the case of a passenger with an asymptomatic intrapulmonary cyst in whom a severe case of cerebral gas embolism developed during an aircraft flight. The decrease in ambient pressure during the aircraft climb resulted in expansion of the cyst volume based on Boyle’s law (pressure x volume = constant). Due to the cyst expansion, we believe tears in the wall led to the leakage of air into the surrounding vessels followed by brain gas emboli. Adult patients with intrapulmonary cysts should be strongly considered for cyst resection or should at least be advised to abstain from activities leading to considerable changes in ambient pressure.
Key Words: air embolism • bronchogenic cyst • gas embolism • pulmonary cyst
|
Introduction
|
|---|
Even for passengers with medical conditions, air travel is thought to be safe. And even though > 1 billion passengers travel by airplane throughout the world every year, along with a high prevalence of respiratory conditions in the population in general, the incidence of in-flight emergencies is low.1
To our knowledge, only three similar cases of cerebral gas embolism arising from an intrapulmonary cyst have been reported in the literature published in the English language. None of the patients in these cases, however, demonstrated the actual gas emboli on cerebral imaging.234 We describe the case of a passenger with an asymptomatic intrapulmonary cyst in whom a severe case of cerebral gas embolism developed during a flight. This new case report supports the idea that adult patients with intrapulmonary cysts should be strongly considered for cyst resection, or at least should be advised to abstain from activities leading to considerable changes in ambient pressure.
|
Case Report
|
|---|
A 71-year-old man experienced the sudden onset of right-sided chest discomfort shortly after the takeoff of a commercial flight. He never reported dyspnea. Several minutes later, a headache developed followed by a sudden loss of consciousness. A physician on the airplane found his vital signs to be normal. Because the patient was unresponsive, the flight was diverted for further care of the passenger. The patient had a history of anticardiolipin syndrome and prior deep vein thrombosis, Sneddon syndrome (cerebrovascular disease associated with livedo reticularis), coronary artery disease status post-coronary artery bypass graft surgery, and permanent pacemaker for paroxysmal atrial fibrillation. He was receiving therapy with clopidogrel and warfarin. On arrival at the hospital, he was unresponsive and had a Glasgow coma score of 3. His pulse oximetry showed an arterial oxygen saturation of 96% on a fraction of inspired oxygen of 0.45. Funduscopy did not demonstrate bubbles within the retinal arteries. The patient was then orally intubated for airway protection and placed on mechanical ventilation. A chest radiograph revealed a right pulmonary cyst (Fig 1
). A chest CT angiogram demonstrated no pulmonary embolism and a large right intrapulmonary cyst with an air-fluid level (Fig 2
). An initial head CT scan demonstrated several gas emboli (Fig 3
). His international normalized ratio was 4.0. Troponin I measurements were as high as 17.2 µg/L, suggesting a gas embolism to the heart resulting in myocardial damage. Because the patient’s neurologist was at our institution, the family requested his transfer. Approximately 48 to 72 h after the initial event, the patient arrived at our hospital in a comatose state. The findings of contrast-enhanced echocardiography were compatible with an intrapulmonary shunt and demonstrated pulmonary artery pressures that were within normal limits. A repeat head CT scan demonstrated severe cerebral edema. No more brain gas emboli were seen. On review of his prior imaging studies from our institution, a smaller right intrapulmonary cyst was noted on an abdominal CT scan that had been performed several months prior because of abdominal discomfort. On further questioning of the patient’s wife regarding his history of flying, she reported an episode of syncope during another flight a few years ago. This was attributed to his hypercoagulable state and/or cerebrovascular disease. It was felt to be too late to attempt hyperbaric oxygen (HBO) therapy. Despite some improvement in cerebral edema after therapy with high-dose steroids, his overall clinical picture did not improve, and he died 16 days after initial presentation.
View larger version (106K):
[in this window]
[in a new window]
[Download PPT slide]
|
Figure 2.. Chest CT scan demonstrating the intraparenchymal bronchogenic cyst (top arrow) with air-fluid level (bottom arrow). The fluid is most likely blood. Note the proximity to the right main pulmonary artery.
|
|
|
Discussion
|
|---|
The decrease in ambient pressure during the aircraft climb resulted in an expansion of the cyst volume based on Boyle’s law (pressure x volume = constant). We agree with Zaugg et al2 that a "stopcock valve mechanism" might have occurred, allowing air to enter but not to escape from the cyst. Due to the cyst expansion, and the stopcock valve mechanism, we believe that tears in the wall led to the leakage of air into the surrounding vessels followed by brain gas emboli. In our patient, the air could have leaked into either the pulmonary veins or artery due to the proven existence of an intrapulmonary shunt. The proximity of the cyst to the right main pulmonary artery and the air-fluid level suggest that at least a portion of the leak occurred to this vessel. Although the presence of the intrapulmonary shunt might have increased the risk and/or severity of the cerebral gas embolism in this case, it may not have been necessary for its occurrence.
Although no randomized controlled trials of HBO therapy for a gas embolism have been conducted in humans, it is the general thought that it is the most effective first-line therapy and should be instituted as early as possible. Ideally, our patient should have received HBO therapy on his initial presentation to the first hospital.
Based on the findings of the British Thoracic Society Standards of Care Committee,1 adults with a history of air travel intolerance with respiratory symptoms such as dyspnea, chest pain, confusion, or syncope, or patients with conditions worsened by hypoxemia (eg, cerebrovascular disease, coronary artery disease, and heart failure) should have a preflight assessment. Our patient was fully anticoagulated, but unfortunately, his pulmonary cyst was never assessed.
Although there is likely a larger number of patients with emphysema or other bullous lung diseases who travel by air, the reported cases of barotraumas are sparse. It is possible that cerebral gas embolism has not been reported in patients with emphysema due to the destruction of the capillary bed.5 While dysplastic embryonal vessels are part of the wall of intraparenchymal bronchogenic cysts,2 the presence of vessels in patients with emphysema is significantly diminished. Another plausible explanation for this low incidence when compared to divers, is the greater height needed to ascend to result in the same change in pressure (3,000 feet during an airplane climb vs 3 feet during a diving ascent to result in a pressure difference of 80 mm Hg).2
Because of the unpredictable long-term prognosis of bronchogenic cysts in adults, these cysts should be surgically resected in every operable candidate.6 In patients who are not candidates for surgical resection or who decline surgery for treatment of their cysts should be cautioned to abstain from activities leading to considerable changes in ambient pressure, such as flying, diving, or high-altitude climbing.
|
Footnotes
|
|---|
Abbreviation: HBO = hyperbaric oxygen
The authors have reported to the ACCP that no significant conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.
Received for publication January 16, 2006.
Accepted for publication February 15, 2006.
|
References
|
|---|
- . British Thoracic Society Standards of Care Committee. (2002) Managing passengers with respiratory disease planning air travel. Thorax 57,289-304[Free Full Text]
- Zaugg, M, Kaplan, V, Widemer, U, et al Fatal air embolism in an airplane passenger with a giant intrapulmonary bronchogenic cyst. Am J Respir Crit Care Med 1998;157,1686-1689
- Closon, M, Vivier, E, Breynaert, C, et al Air embolism during an aircraft flight in a passenger with a pulmonary cyst: a favorable outcome with hyperbaric therapy. Anesthesiology 2004;101,539-542[CrossRef][ISI][Medline]
- Cable, G, Keeble, T, Wilson, G Pulmonary cyst and cerebral arterial gas embolism in a hypobaric chamber: a case report. Aviat Space Environ Med 2000;71,172-176[Medline]
- West, JB Obstructive diseases. West, JB eds. Pulmonary pathophysiology: the essentials 2003,51-80 Lippincott Williams and Wilkins. Philadelphia, PA:
- Patel, S, Meeker, D, Biscotti, C, et al Presentation and management of bronchogenic cysts in the adult. Chest 1994;106,79-85[Abstract/Free Full Text]
TOP
Abstract
Introduction
