Letter to the Editor:

To the Editor:

Cryoablation is increasingly used to treat unresectable malignant tumors. During cryotherapy it may not be possible to immediately remove the freezing element from an organ in an emergency without active thawing. We recently cared for a patient that illustrated the risk of the frozen instrument during cryotherapy of the kidney in the prone position and the benefits of proactive communication.

A 65-year-old man was scheduled for a computed tomography (CT)-guided percutaneous cryoablation of a right kidney tumor. The patient had multiple medical problems including obesity, obstructive sleep apnea, and a difficult airway. The procedure, which was to include multiple advancements and withdrawals of the patient inside and outside of a CT scanner, was to be performed under general anesthesia with an endotracheal tube and in the prone position.

Once the freezing process was initiated, the patient could not be immediately turned supine in the event of an emergency.¹ Therefore, the interventional radiology (IR) team agreed to verbally notify the anesthesia team who would perform a quick check to rule out any airway or hemodynamic issues. The treatment was concluded uneventfully and the patient was turned to the supine position and his trachea was extubated upon full awakening.

Percutaneous cryoablation is increasingly utilized to treat small renal masses that are concerning enough to warrant treatment but reside in poor surgical candidates.² Renal masses are frequently approached posteriorly which requires the patient to be in the prone position. The probes will be firmly anchored to the patient’s tissues during the tumor freezing process. They are either allowed to thaw spontaneously, which takes approximately 10 minutes, or they are actively thawed, which takes up to 2–3 minutes. Any attempt to forcibly remove the probes prior to complete thawing may result in tissue avulsion and hemorrhage.³

This patient had multiple comorbidities that increased his risk of complications in the prone position. The fact that the frozen probes could not be immediately removed in an emergency meant that the patient could not be immediately turned supine. The IR team, therefore, alerted the anesthesia team each time freezing was about to start.

Cryoablation of kidney tumors is sometimes performed with the patient placed in the decubitus position with the treatment side down.⁴ The decubitus position allows access to the airway but would compromise the efficacy of cardiopulmonary resuscitation.

During cryotherapy the anesthesia professional needs to be familiar with the potential risk of the frozen instrument. Communication with the proceduralist before the start of each freezing cycle is important for patient safety.

Dr. Hannallah is an Associate Professor in the Department of Anesthesiology at Medstar Georgetown University Hospital in Washington, DC.

Dr. Parekh is a resident physician in the Department of Anesthesiology at Medstar Georgetown University Hospital in Washington, DC.

Dr. Baghai was an interventional radiology fellow in the Department of Radiology at Medstar Georgetown University Hospital, and is currently employed with Mid-Atlantic Permanente Medical Group, Rockville, MD.

Drs. Hannallah, Parekh, and Baghai report no conflicts of interest for this article.

References:

1. Shafir M, Shapiro R, Sung M, Warner R. Cryoablation of unresectable malignant liver
   tumors. Am J Surg 1996;171:27–31.
2. Young J, Kolla S, Pick D, Sountoulides P, Kaufman O, Ortiz-Vanderdys C, et al. In
   vitro, ex vivo and in vivo isotherms for renal cryotherapy. The Journal of
   Urology 2010;183:752–8.
3. Shock S, Laeseke P, Sampson L, Lewis W, Winter III T, Fine J, Lee, Jr F. Hepatic
   hemorrhage caused by percutaneous tumor ablation: radiofrequency ablation versus cryoablation in a porcine model. Radiology 2005;236:125–31.
4. McClung C, Wright A, Pierce K, Posniak H, Perry K. Percutaneous cryoablation of a
   small renal lesion necessitating modified lateral decubitus position. J Endourology 2007;21:1339–40.