The use of spray cryotherapy (SCT) for airway lesions demands stellar intraoperative airway management and vigilance for intraoperative desaturations.
“The fact that we are putting liquid nitrogen into the airway, and only doing intermittent ventilation in some cases, in patients who often have diseased lungs to begin with—that demands intraoperative vigilance,” explained Megan Friedman, DO, from the Icahn School of Medicine, Mount Sinai Health System, in New York City.
SCT is tissue ablation therapy that uses a low-pressure spray of liquid nitrogen through an endoscopic catheter. When used in airway lesions, cells may be selectively destroyed while the underlying collagen tissue structure is preserved. The process provides a scaffold for healthy tissue to regrow while reducing the risk for perforation.
“This is not a common procedure,” Dr. Friedman noted during the 2015 New York State Society of Anesthesiologists PostGraduate Assembly in Anesthesiology. “In patients with tracheal stenosis—whether they have cancer or developed stenosis after having a prolonged tracheostomy, or Wegener’s granulomatosis, among other conditions—they are limited in where they might go to get this done, and the procedure comes with a handful of challenges.”
One potential challenge is the need for adequate ventilation, as the liquid-to-gas ratio of nitrogen is 1:694. A review noted that liquid nitrogen’s rapid expansion has the potential to displace oxygen and expand the lungs to a volume that might exceed their capacity, “at which point, pneumothorax or barotrauma may occur.” Initial reports of the use of spray cryotherapy noted a significant rate of complications, ranging from hypotension, to bradycardia, to operative and postoperative death (Ann Thorac Surg 2012:94:199-203; discussion 203-204).
A Retrospective Look
In recognizing the potential dangers of this technique, Dr. Friedman and her team underwent a retrospective chart review of Mount Sinai St. Luke’s patients between 2013 and 2015 who underwent SCT for upper airway lesions.
Thirty-eight SCT procedures were analyzed, which included patients who presented with subglottic stenosis after prolonged tracheostomy, cancerous lesions, sarcoidosis, Wegener’s granulomatosis and Kaposi sarcoma. Each patient underwent one of three methods of airway management: in situ tracheostomy, intermittent jet ventilation (IJV) and the use of an endotracheal tube (ETT). In all cases, patients received total intravenous anesthesia.
During the procedure, passive ventilation of the nitrogen was confirmed by watching the gas exit the airway; disconnecting the patient from the ventilator; and, if ETT was used, deflating the cuff in the ETT.
Three complications were analyzed in the retrospective analysis: intraoperative desaturations, as defined as oxygen saturation less than 90% for more than 15 seconds; postoperative reintubation; and barotrauma.
“Not surprisingly,” Dr. Friedman noted, “the patients who had undergone intermittent ventilation had the most episodes and the longest episodes of desaturation.”
Of the 38 cases performed, there was an average of 1.46 episodes of desaturations, each lasting approximately 40 seconds. Patients undergoing IJV had an average of 1.83 episodes, in situ tracheostomy patients had an average of 1.16 and the ETT group had an average of 0.43.
There was no evidence of barotrauma during any of the three procedures, suggesting that the technique of watching the nitrogen exit the airway, disconnecting the patient from the ventilator and deflating the cuff in the ETT is a sufficient and reasonable way of preventing complications.
“In the future, we’d like to try to continue to collect more data,” Dr. Friedman explained. “And we’d like to analyze the episodes of desaturation based on the location and extent of the lesion being treated.”