Hydatid disease, caused by Echinococcus granulosus, is endemic in some Mediterranean countries, the Middle East, South America, Australia and New Zealand. Echinococcus cysts of the liver usually have the tendency to grow and, after a number of years, depending on the patient, complications such as infection of the cyst, intrabiliary rupture, intraabdominal rupture, and intrathoracic rupture can appear (1,2). Intrathoracic rupture of hepatic Echinococcus cyst is a rare complication that always implies erosion of the diaphragm, followed by rupture of the cyst into a bronchus, the pleural cavity, or both. We present a case of complete intrabronchial rupture of hepatic Echinococcus cyst associated with mechanical ventilation.
An 80-yr-old woman was admitted to the hospital because of hip fracture. Her medical history included chronic obstructive pulmonary disease and Echinococcus cyst of the liver that was thought to be inactive and harmless. During the month preceding the accident she suffered from an irritating cough without fever, and in the last week she began coughing up purulent sputum and started taking antibiotics. Her chest radiograph on admission to the hospital (Fig. 1) revealed pulmonary infiltrates and atelectasis of the right lower lobe, elevation of the right diaphragm, and some calcifications in the region of the hydatid cyst of the liver.
During the first 24 h of hospitalization she presented acute respiratory failure II that was unresponsive to conservative methods. This was followed by endotracheal intubation and positive pressure mechanical ventilation. One hour after mechanical ventilation was begun, the arterial oxygen saturation suddenly decreased and there was unexpected ventilation difficulty. The airways flooded with cyst contents. A chest radiograph after tracheal suctioning (Fig. 2) revealed that the hydatid cyst of the liver had completely ruptured into the bronchi. An ultrasonography examination at this time showed the empty calcified hydatid cyst of the liver.
The patient immediately developed cardiovascular instability that was attributed to anaphylaxis, and she was treated with hydrocortisone, epinephrine, and crystalloids. Despite vigorous resuscitative efforts, she died 3 h after the beginning of the incident. Her death was thought to be the result of anaphylaxis and there was no necropsy.
In humans, the liver is affected by Echinococcus granulosus in 55% to 70% of patients. Thoracic complications of hepatic hydatid cysts result from the proximity of hydatid cysts in the liver and the diaphragm and are seen in approximately 0.6% to 16% of cases (3,4).
Several factors, such as pressure gradient between thoracic and abdominal cavities, mechanical compression and ischemia of the diaphragm, sepsis in the hepatic cyst, or chemical erosion by bile, participate in promoting intrathoracic evolution of hydatid cysts of the hepatic dome.
The clinical presentation of thoracic involvement of hydatid cyst of the liver is predominately pulmonary, with the most frequent symptoms being chest pain and productive cough that appears 1 to 24 months before the final diagnosis (5,6). Chest radiograph is not always clear enough to assign the condition, and the basal shadow usually leads someone to suspect a subdiaphragmatic process (3,5–7). Ultrasonography, computed tomogram scan, or magnetic resonance imaging can confirm the diagnosis, and classification based on the degree of evolution of the diaphragmatic or thoracic involvement has been proposed (4).
Rupture of a hepatic hydatid cyst may occur spontaneously or after trauma, and adhesion formation determines whether the rupture will be confined to lung parenchyma, free pleural space, or both. Allergic reactions can appear after the rupture of a hydatid cyst and can range from mild hypersensitivity to fatal anaphylactic shock (8,9).
In the present case, the clinical findings and the chest radiograph were not correlated with the Echinococcus cyst in the liver before the endotracheal intubation, and the final diagnosis occurred after the massive rupture of the hydatid cyst to the bronchi. It seems that the increased intrathoracic pressure as a consequence of mechanical ventilation led to this accident, in which the management of positive pressure ventilation, especially via simple endotracheal tube, turned out to have fatal consequences. This is the first report of a massive rupture of a hepatic hydatid cyst into the bronchi associated with mechanical ventilation.
The appropriate treatment of hydatid cysts of the liver is determined by several factors; however, surgery is clearly indicated in cysts of any type that have any form of complication (10). In pulmonary hydatid cysts, most authors recommend double-lumen intubation of the trachea during surgery so that it is possible to control ventilation and prevent flooding of the contralateral lung in case of rupture (11,12). We believe that this choice in ventilation should be extended to some hydatid cysts of the liver with thoracic involvement.
In conclusion, echinococcal cysts always carry the risk of rupture and can cause anaphylactic shock. Furthermore, the timing and the predisposing factors of rupture—such as mechanical ventilation in our case—are not always predictable; thus, definite early intervention is required, especially in complicated cysts.
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