New Ethmoid Spacer For Drug Delivery
Martin J. Citardi, MD
Professor & Chair
Since its introduction more than 3 years ago, balloon catheter dilatation of sinus ostia has engendered considerable controversy. In 2008, a variety of publications have provided additional information about the technology and its apparent efficacy. At the recent American Academy of Otolaryngology (AAO) meeting in Chicago, two presentations highlighted the introduction of a new device that that applies balloon catheter technology to the ethmoid sinuses.
Acclarent (Menlo Park, CA), the company that originally introduced balloon sinuplasty, has developed the Relieva Stratus MicroFlow Spacer, a new device described by the company as “a temporary implant delivered directly to the ethmoid complex [with] a reservoir with hundreds of precision-formed micropores …[for] targeted, local bathing of paranasal sinus cells.”1 Essentially, the device can be considered as a leaky balloon that is deployed in the ethmoid sinuses under endoscopic visualization and fluoroscopic guidance. After placement, the MicroFlow Spacer can be secured to the site and left in place for 2 weeks. According to the package insert, only saline should be instilled through the device, which is designed for “moistening the ethmoid cells.”2
Two abstracts presented at the 2008 AAO annual meeting report initial experiences with this new product:
- Chris Melroy MD, and Fred Kuhn MD report an initial description of the device and its application in 12 cadaveric ethmoid sinuses.3 This presentation highlighted the technique for the use of device and noted no apparent orbital or skull base injuries. The authors measured the position of the stent after deployment through endoscopic dissection and CT scan. (This project was supported by Acclarent.)
- Fred Kuhn MD, Chris Melroy MD, Howard Levine MD, and Andrew Diamond MD presented a clinical series in which the new device was used in 22 sides (13 patients) for the delivery of triamcinolone acetate over a period of 2-4 weeks.4 After spacer deployment, each spacer was filled with 0.3 ml of 40 mg/ml triamcinolone in the operating room. Lund-MacKay CT scores dropped from 3.9 to 1.6 (59% reduction), and SNOT-20 scores dropped from 1.91 to 1.12 (p<0.001). (This project was also supported by Acclarent.)
In both presentations, the authors speak about “drug-eluting stents”, devices that are potential game-changers for surgical rhinology, since they would offer the ability to modulate the inflammatory milieu of the paranasal sinuses. Strictly speaking, the device is not a “drug-eluting stent” in the same way that certain cardiac stents incorporate and deliver specific amounts of drug for therapeutic effect. The term “drug elution” implies the gradual release of biologically active compound from a polymer. Clearly, this device does not offer that property; instead, the Acclarent MicroFlow Spacer is merely a passive device through which a liquid may be applied. It offers none of the advantages of true drug elution.
The rationale for the device design is unclear. For decades, otorhinolaryngologists have placed instruments in the ethmoid sinuses and more recently, endoscopic techniques have been developed for precise dissection of the ethmoid sinuses. In light of this, why is fluoroscopy necessary for the placement of the MicroFlow Spacer? Why must the device be placed over a wire? Why can’t it just be directly placed in the ethmoid sinuses under endoscopic visualization? Furthermore, the device’s stated intent of providing moisture to the sinuses can be achieved quite well through patient-administered irrigations and perhaps irrigations administered under endoscopic visualization. Thus, the MicroFlow Spacer seems to be an over-engineered solution to a problem that does not really exist. The bottom line is that we can access the ethmoid sinuses quite well without the MicroFlow Spacer and its apparatus for introduction.
The most practical aspect of any new device is its potential impact on patient care. The second presentation begins to answer this question, since it reported significant improvement in both symptoms and CT scores after administration of triamcinolone through the device. This preliminary trial is far from conclusive. The absence of a control group is an obvious deficiency. There is no way to access the potential impact of the administration of steroids topically (through direct instillation without the device) or systemically (steroid dose pack). It is quite possible that the device itself had little to do with the apparent good results associated with the therapeutic intervention. Clearly, additional, more formal trials are warranted.
The authors of these reports should be congratulated for their innovative approaches to long-standing problems. These early reports are quite intriguing; nonetheless, they are far from conclusive. Before we radically alter our treatment paradigms, additional clinical investigations are warranted.
- http://www.acclarent.com/professional/products.html (accessed November 2, 2008).
- http://www.acclarent.com/pdf/dummy4_old.pdf (accessed November 2, 2008).
- Melroy CT, Kuhn FA. Safety of ethmoid sinus drug-eluting catheter insertion. Presented at the 2008 American Academy of Otolaryngology-Head & Neck Surgery annual meeting (Chicago, IL; September 21-24, 2008).
- Kuhn FA, Melroy CT, Levine HL, Diamond AJ. Drug-eluting spacer for chronic ethmoid sinusitis treatment. Presented at the 2008 American Academy of Otolaryngology-Head & Neck Surgery annual meeting (Chicago, IL; September 21-24, 2008).