Use of a Flexible Cryoprobe for Removal of Tracheobronchial Blood Clots

Discussion

This case highlights the successful use of a cryoprobe in the management of airway obstruction during flexible bronchoscopy. The index case presented with acute respiratory failure resulting from left-lung collapse secondary to a blood clot, which was removed by cryoextraction, leading to resolution of respiratory failure.

Airway obstruction from endobronchial blood clots can occur in several disorders. These include both benign (pulmonary tuberculosis, bronchiectasis, vasculitides, invasive fungal infections, bleeding disorders, post-tracheotomy, trauma during suctioning, and others) and malignant (bronchogenic carcinoma, carcinoid tumors, metastatic pulmonary nodules, and others) conditions. Endobronchial blood clots may be preceded by sentinel hemoptysis (mild or massive); however, ∼30% of patients may present with respiratory failure without a prior history of hemoptysis.^1,2 Treatment involves hemodynamic stabilization, identification of the cause of hemoptysis, control of bleeding, and removal of the endobronchial clot (if causing respiratory failure). In our case, the cause of bleeding was the use of antiplatelet therapy for treatment of the cerebrovascular accident, which complicated a recent tracheotomy performed for airway protection.

Removal of endobronchial clots can be accomplished by either flexible or rigid bronchoscopy. During flexible bronchoscopy, clot retrieval can be performed piecemeal using biopsy forceps or by withdrawal of the bronchoscope with the clot adhering to the tip through continuous suction. The clot can also be displaced using a Fogarty catheter or lysed with thrombolytic agents, followed by suctioning.^1–3,6,7 Thrombolytic agents could theoretically pose a risk for rebleeding, whereas manipulation with a Fogarty catheter across the clot is a blind procedure that itself can induce minor trauma.^8,9 Furthermore, these techniques take more time; in our case, due to our patient's critical condition with respiratory failure, we needed a procedure that would result in rapid clot extraction. Hence, we chose a cryoprobe, the use of which not only results in immediate improvement but can also cause hemostasis by vasoconstriction and slowing of blood flow. Rigid bronchoscopy has been used in cases in which attempts to retrieve the clot by flexible bronchoscopy failed. However, rigid bronchoscopy involves the use of general anesthesia, which may be associated with an increase in morbidity (and mortality), especially in patients such as this index case.¹⁰

The use of cryoprobes for successful extraction of endobronchial blood clots has also been described previously (Table 1).^{3,8,9,11–13} There are 2 types of cryoprobes: flexible and rigid. The former can be used through both flexible and rigid bronchoscopes (with a flexible scope inserted through the rigid barrel). Rigid cryoprobes are larger; however, we have found them to have limited utility because they are not truly rigid, and the growth or clots tend to fall off due to lack of stability. Although initially used for management of centrally located airway tumors, the current equipment has widened the scope of cryosurgery in the management of various airway disorders such as removal of foreign bodies, management of benign strictures and granulation tissue, and lung biopsies.^4,5,14,15 Because cryoprobes can be used for several indications during flexible and rigid bronchoscopy and equipment is not unduly expensive (approximately $10,000), we believe that cryotherapy units should be part of the diagnostic and therapeutic armamentarium of every interventional pulmonology unit. Furthermore, there is a short learning curve, as it just requires proper maneuvering of the probe, which can be done by any experienced bronchoscopist.

The endobronchial uses of cryotherapy techniques are based on the following principles: (1) cryoablation involving repeated cycles of freezing and thawing, leading to tissue destruction as a result of cryothrombosis and intracellular crystallization, or (2) cryoadherence, wherein the object of interest (tumor, foreign body, or other) adheres to the cryoprobe due to crystallization of the water molecules at the interface. The object can then be extracted en bloc along with the probe, a process called cryoextraction. When it is used for restoring the patency of an airway by removing a tumor, it is called cryorecanalization. The use of a cryoprobe is safe in the airways, as it avoids injury to the relatively cryo-resistant tracheobronchial cartilage.⁵ Although endobronchial objects or foreign bodies with high-water content are ideally suited for cryoextraction, recent evidence suggests that this technique can also be used to extract inorganic objects with low water content. In an ex vivo study involving retrieval of 18 commonly aspirated objects using cryoprobes, many inorganic objects (hairpin, glass, stapler, pill) with a low water content could be removed, indicating the utility of cryoprobes in wider indications than previously thought.¹⁶ In conclusion, our case demonstrates that bronchoscopic cryoextraction is a simple and safe modality for removal of endobronchial blood clots and can be used to avoid invasive procedures such as rigid bronchoscopy.