PULMONARY HYDATID DISEASE

Prof. Abdulsalam Y Taha

School of MedicineFaculty of Medical Sciences

University of SulaimaniIraq

https://sulaimaniu.academia.edu/AbdulsalamTaha

Pulmonary Hydatid

Cysts

The CystHydatid disease is a parasitic infection caused by Echinococcus granulosus. The cyst lodges most commonly in the liver and the lungs, respectively. Morphologically, hydatid cyst consists of three layers and hydatid fluid. The first layer is the pericyst or adventitia which is the host tissue formed by the lung as a reaction to the foreign body (parasite). The other two layers, the laminated membrane (external layer of the cyst) and the germinative layer (inner layer of the cyst), belong to the parasite( .The cyst fluid resembles water in appearance which may contain daughter vesicles.

The cysts exist in different forms: intact or ruptured, single or multiple, unilateral or bilateral, solely located in the lung or concomitantly in other organ lodgments (especially in the liver).

The goal of surgical therapy in pulmonary hydatid disease is to remove the cyst while preserving as much lung tissue as possible. The surgical method may be different in the intact (simple) and ruptured (complicated) cysts. The operation has two steps: a) removal of the germinative layer, b) management of the residual pulmonary cavity. Simple cysts are generally removed after needle aspiration or enucleation without needle aspiration.

Enucleation cannot be performed in ruptured cysts. The lung cavity that remains after removal of the cyst may be left as it is or obliterated by sutures from within the cavity in regard to the size and location of the cyst. However, the bronchial openings in the cavity must be closed by sutures in all cases. Rarely, hydatid cysts can occur in other thoracic structures such as pulmonary artery, chest wall or diaphragm. Those cysts located on the liver dome are operated by transthoracic–transdiaphragmatic approach.

A perforated hydatid cyst located in the right lower lobe of the lung. The air is seen between the laminated membrane and the cyst.

A computerized tomography of the chest showing 2 intact hydatid cysts located in the right lower lobe of the lung.

A CT appearance of a ruptured hydatid cyst located in the right parahilar area.

Two ruptured cysts located in the right lower lobe of the lung. The fluid of the smaller one is completely expectorated while the larger

cyst seems still having the fluid. Partial or complete expectoration of the fluid after cyst rupture is completely related to the presence or

absence of an open bronchiole adjacent to the cyst.

The macroscopic appearance of the hydatid cyst in the lung

General principles of the operationThe aim of surgery in pulmonary hydatid cyst is to remove the cyst completely while preserving the lung tissue as much as possible . Lung resection is performed only if there is an irreversible and disseminated pulmonary destruction. Careful manipulation of the cyst and adherence to the precaution to avoid the contamination of the operative field with the cyst content is the imperative part of the operation. The cysts located on the liver dome are easily accessible and resected via right thoracotomy with the transdiaphragmatic approach.

Finding the cystOnce the chest is opened, the lung is palpated gently to avoid the rupture of the cyst. The anesthesiologist deflates the lung in the operated site and the surgeon finds the cyst located in the depth of the lung tissue easily if it is not very small or if it is located superficially. The smaller cyst located within the parenchyma is found by gentle palpation of the lobe that is obtained to have the cyst in computerized tomography of the chest.

Covering the adjacent lung with the towelsBecause there is always a risk of spillage of daughter vesicles into the operating field during the operation, the lung should be surrounded by sterile towels immediately at the beginning of the operation. Only the area of the cyst-containing lung must be in the operating field before any attempt be made to remove the cyst or aspirate the cystic fluid

Removal of the cystThe intact cysts are removed in one of the two ways: removal of the cyst following aspiration of the cystic fluid, or by enucleation of the cyst without aspiration of the fluid. Ruptured cysts can only be removed by aspiration of the cyst content, then by the removal of the cyst membrane

1. Removal of the cyst following aspiration of the cystic fluid. The intact cysts may contain living vesicles suspending in the cystic fluid. A careful aspiration of the fluid prevents the dissemination of the vesicles into the chest or to the bronchus. The aspiration is performed with a syringe adapted to a 3-valved aspiration catheter. Ten percent povidone iodine may be injected into the cyst through the same catheter to kill the living vesicles within the cyst

When minimal fluid is left in the cystic cavity, the needle insertion site is enlarged and suction apparatus is inserted into the cyst to aspirate the residual fluid completely. After the aspiration has been completed, the edges of the pericyst are enlarged in an extent so that the laminated membrane can easily be taken out. The assistant grasps the edges of the pericyst and the surgeon takes the laminated membrane (which is generally disrupted) out of the cavity

2. Enucleation of the intact cyst without needle aspiration.

Enucleation is performed by removing the intact cyst from the cystic cavity by a careful dissection between the pericyst and the laminated membrane. Pericystic layer is incised or cut superficially until the laminated membrane of the cyst is seen. This incision is then extended to a certain length so that the delivery of the cyst is possible. The pericyst is separated from the laminated membrane patiently by sharp and blunt dissections. Inflating the lung by the anaesthesiologist and gentle and adjusted manual pressure over the surrounding lung by the surgeon assist the delivery The cyst is delivered over the gauze steeped in povidone iodine and then taken out of the chest with the gauze.

Management of the residual cavity

When the cyst is removed, the remaining pulmonary cavity is cleaned completely with sterile gauze and, observed for the presence of air leakage. Air leakage can be seen by direct observation and also by filling the cavity with sterile saline solution. The cavity is filled with the fluid only after closure of the major bronchial opening (s) has been performed .

The simple alveolar air leakage is not an important issue, which can easily be managed during the obliteration of the cavity with imbrication sutures. The obliteration (capitonnage) is made by circumferential imbricating separated sutures with a 3-0 chromic catgut or a 3-0 coated polyglactin from within the cavity

When two steps of the resection of the cyst(s) have been accomplished, the towels surrounding the lung are taken out from the chest using the grasping instruments. Because the towels may contain cystic material, the hands must not be used in their removal from the operative field.

Transthoracic–transdiaphragmatic approach to the subdiaphragmatic hydatid cysts

Not infrequently, thoracic surgeons are asked for the management of hydatid cysts located at the upper part (subdiaphragmatic location) of the liver. A thoracotomy provides better exploration and access to the cyst located in this area when compared to the laparotomy.

The principal of the resection of liver cyst is similar with the pulmonary cyst; however, there are important technical differences between the two operations: the hepatic cysts contain daughter vesicles more commonly than the pulmonary cysts. For this reason, a scolocidal agent (to kill the parasite) such as hypertonic saline solution or 10% povidone iodine must be injected through the diaphragm into the cyst to prevent the spreading of the living vesicles in the abdomen or thorax before the opening and removal of the cyst. The diaphragm is cut using a scissors and its muscle is separated from the cyst by blunt and sharp dissections with no pressure over the cyst. When the intracystic pressure has been lowered, the cyst is opened from the uppermost part of the cyst and its content is aspirated by a large holed suction device.

Because the cyst contains numerous daughter vesicles that are not technically possible to aspirate with a suction device or take out by a grasper, a spoon is used to evacuate the cavity completely

A rubber tube is inserted into the cavity and taken out from the skin under the diaphragm. The edges of the cyst's fibrous capsule are closed with mattress sutures.

Removal of the hydatid cysts from the main pulmonary artery

Very rare, but a highly fatal situation, is the lodgement of the hydatid cyst in the pulmonary artery. Main pulmonary artery must be investigated carefully for the presence of ‘filling defect’ in every case with multiple pulmonary hydatid cysts. The removal of the hydatid cyst is performed with pulmonary arteriotomy via sternotomy under total circulatory arrest or cardiopulmonary bypass.

Resection of the hydatid cyst located on the thoracic wall

The chest wall is one of the unusual locations of the hydatid cyst. Because there is no cavity left after the removal of the cyst on the chest wall, the surgical technique includes only the removal of the cyst.

RESULTSPostoperative complication rate is 0.8–4% for the intact cysts and, 4–6% for the ruptured cysts. The most common postoperative complications are prolonged air-leak, empyema and, pneumonia due to the aspiration of cystic content or washing solution through an open bronchus adjacent to the cyst. The mortality rate is lower than 1% in the intact cysts and around 2% in the complicated cysts. The mortality is closely related to the presence of unrecognized cysts in the central nervous system (CNS) or in the proximal part of the pulmonary artery. The size of the cyst is also another factor which maybe associated with the increased complication rate.The CNS and the pulmonary arteries must be evaluated before surgical attempt is made in every case with disseminated hydatidosis. Recurrence rate is between 1 and 6%. Adherence to the precaution to avoid spreading of the cystic material and, the use of albendazole in selected patients decreases the recurrence rate. Pulmonary resection (i.e., lobectomy) is necessary in less than 10% of the patients.

Indications for resection in pulmonary hydatid disease

Indication Number of patients %

Huge simple cyst causing lobe destruction 5 38.4Suspicion of a tumour 1 7.6Infected ruptured cyst 5 38.4Hydatid broncheictasis 1 7.6Life-threatening haemoptysis secondary tocentral hydatid cyst eroding pulmonaryvessel. 1 7.6Total 13 100

Pulmonary hydatid cyst is endemic in our country. It is responsible for most of the thoracotomies in our practice. In Faisal Haba's series, surgery for pulmonary hydatid cyst constituted 25-35% of thoracotomies. Parasitic infestation by hydatid cyst when complicated is a common indication for resection in Iraq. Elhassani reported a 28% of cases treated by pulmonary resection for pulmonary hydatid cyst while 20% of patients with pulmonary hydatid disease required resection in Faisal Haba series.

The treatment for hydatid disease is surgical removal of the cyst and its contents with preservation of lung parenchyma. Every trial should be done to remove as little as possible of functioning lung tissue in order not to affect pulmonary functions. Pulmonary resection is reserved for the simple giant cyst that causes permanent and irreversible changes in the affected part of the lung and for the complicated cyst where infection has caused lung abscess. Resection is also indicated when there are multiple daughter cysts within the mother cyst. In patients with massive haemoptysis or recurrent suppuration following the removal of the cyst, resection of the involved part of the lung is advisable. Bronchobiliary fistula is another indication for lung resection in PHC .

AN 8 YEAR OLD BOY WITH INTACT HC IN LLL

To summarize the case: The diagnosis of intact PHC in an endemic area is not difficult. Plain radiographic appearance of (full moon against the dark sky) is characteristic. The main concern is the surgical removal of the cyst and its contents safely, without spilling the scolices-rich fluid into the surgical field and thus avoiding recurrence and surgical closure of the bronchial fistulae to achieve early and full lung expansion postoperatively. Safe removal requires protection of the airways from fluid spillage and drowning during surgery. This is the combined responsibility of the surgeon and anaesthesiologist. No double-lumen endotracheal tubes are designed for children due to their small airways.

BILATERAL PULMONARY HYDATIDOSIS