Within the past decade, in-office procedures have become a potential management option for a wide array of sinonasal pathologies, including chronic sinusitis, nasal polyposis, and mucoceles, sinus recirculation. With expanding indications there has also been an expansion in the technology available for use to aid with in-office procedures, notable among which are surgical navigation systems designed for use in an office or procedure room. Though initially intended for use in the operating room, more compact and portable navigation systems have been developed, allowing for easy application to the office setting. Examples of navigation systems designed for in-office use include the Fusion Compact (Medtronic, Jacksonville, FL), the TruDi (Acclarent, Irvine, CA), the Fiagon Navigation (Fiagon, Austin, TX), and the Scopis (Stryker, Kalamazoo, MI).

Standard in-office surgical navigation suite set up should include ( from left to right ) necessary surgical equipment (such as bovie, microdebrider), the patient chair with emitter pad attached t othe headrest, a video display monitor, and the surgical navigation machine (Trudi from Acclarent).

Despite more than 95% of American Rhinologic Society members reporting having surgical navigation available and 99% reporting performing in-office procedures, only 10% report using in-office computer-assisted surgical navigation. Prior methods for ensuring proper positioning of instruments when using them in the office included transillumination or fluoroscopy. However, these methods were not always accurate or convenient for use in the office setting. The advent of in-office surgical navigation has enabled more complex rhinologic procedures to be completed in the office setting.

The most commonly performed of these in-office procedures is balloon catheter sinuplasty, which involves a navigated trackable guidewire, guide catheter, and balloon inflatable via manual pump. The guidewire is used to enter the targeted sinus with navigation, and then the balloon catheter can be inserted into the sinus os or outflow tract over the guidewire. Though balloon catheter dilation has been criticized for overuse, studies suggest symptomatic improvement of chronic sinusitis symptoms and low complication rates, especially in properly selected patients. ^,

Other, more traditional sinus procedures amenable to in-office management with navigation include polypectomy, which improves medication delivery and delays the need for formal endoscopic sinus surgery. Limited endoscopic sinus surgery may also be performed for chronic sinusitis without polyps and recurrent acute rhinosinusitis, isolated fungal balls, or mucoceles. Finally, easily accessible postoperative synechiae or stenosis can be addressed, preventing the need for a return to the operating room.

The simplest rationale for using surgical navigation systems in the office setting is that if we believe that they improve localization and are helpful in the operating room (allow for more accurate, more effective, and safer sinus surgery), then as we migrate some of these procedures into the clinic this technology would offer the same clinical value. In fact, one might argue that being more efficient and precise in our approach might be more valuable in the awake (and potentially nervous and uncomfortable) patient.

The two major categories of technology currently available in surgical navigation systems use either electromagnetic (EM) or optical tracking (OT) to localize an instrument in relation to pre-operative imaging. OT systems function via infrared beams that are reflected to a sensor camera (located over the patient’s head), which locates an instrument through spatial triangulation. Therefore, OT systems require an uninterrupted path between the infrared emitter and the sensor camera—obstruction of this path disrupts the navigation.

In contrast, the majority of in-office surgical navigation systems use EM technology, in which a magnetic field “volume box” is created by an emitter that is placed under the patient’s head or attaches to the side of the table. Instruments are tracked as they enter and exit the magnetic field box. EM systems are generally preferred by surgeons as they avoid the continuous line of sight required by OT systems, which is an important consideration for in-office procedures as the patient must be positioned for comfort in addition to surgeon preference.

Adequate anesthesia is also a critical step in improving patient comfort and cooperation and ensuring the success of the procedure. Local anesthetics may be administered via topical or injected formulations. Classes of local anesthetics used for in-office sinus procedures are esters and amides, which both generally function by inhibiting sodium channels and action potential propagation. Lidocaine (amide) and tetracaine (ester) are two of the most common anesthetics used. Lidocaine has a rapid onset but a shorter effect duration, while tetracaine has a slower onset but a longer effect duration. Importantly, a significantly smaller dose of tetracaine may lead to toxicity compared to lidocaine, and esters are more commonly associated with allergic reactions.

The anesthesia process is generally begun with a combination of 4% lidocaine/oxymetazoline aerosolized spray. Cottonoids soaked with 2% to 7% tetracaine or 4% lidocaine are then placed into the middle meatus and nasal cavity. Alternatively, tetracaine gel may also be used. The gel or cottonoids are then left in place for 15 to 20 minutes to allow for proper anesthesia. Following this period, injection with 1% lidocaine with 1:100,000 epinephrine is performed at involved sites. Furthermore, premedication with a short-acting benzodiazepine or opioid may also be considered on a case-by-case basis. Alternative anesthesia regimens, sometimes utilizing regional blocks, may also be considered.

For in-office navigated procedures, patients are positioned either upright or slightly reclined with the emitter pad of the EM system under their head or attached to the side of the bed. Depending on individual office setups, the navigation system may be integrated within an endoscopic visualization tower by a compact unit or used on a separate tower. Fusion Compact and TruDi both function within all-in-one PC-monitor combination towers that are portable. In contrast, Fiagon Navigation is a device that integrates within a single shelf on a separate video tower. Space is, of course, at a premium in the office examination room, and many systems have dramatically decreased their footprint and overall size to accommodate this. Accurate placement of the emitter pad is imperative to avoid distortion of the EM field. Fiagon and Fusion have pads that attach directly to the patient chair. The TruDi emitter pad is unique in that it can be designed within a headrest that can block unwanted interference from surrounding metal.

With the emitter pad in place, the patient is registered using a preoperative computed tomography scan, and the appropriate instruments are plugged into the system. A wide variety of instru­ments have been developed for in-office use such as vacuum-powered microdebriders, drug eluting implants, rigid sinus seekers, and balloon dilators, most of which may be used with surgical navigation. Other potential trackable instruments include guidewires, malleable pointers, and malleable or rigid suctions.

With the increasing availability of surgical navigation systems, there is a plethora of anecdotal evidence regarding their benefit, as many surgeons confirm their utility, especially for advanced and revision sinus cases. While outcomes regarding in-office surgical navigation specifically have yet to be published, there are numerous studies evaluating its benefit in the operating room setting. It would be reasonable to generalize these studies apply to the in-office setting as well.

Overall, however, strong data proving better clinical outcomes are sparse. Some studies have associated surgical navigation with lower intraoperative blood loss and reduced complication rates. ^, Other studies have reported various improved sinusitis outcome measures and reduction in the need for revision surgery. ^, Unfortunately, such findings have been inconsistently reproducible in subsequent studies. ^, Even larger systematic reviews have produced varying results, with some showing reduced risk of major and minor complications and others concluding that the literature cannot support improved outcomes. ^, These reviews, however, were based on largely retrospective studies with suboptimal research methods. It is important to keep in mind that definitively proving any benefit would require a large prospective randomized study that would be ethically questionable in today’s era of sinus surgery, where surgical navigation is widely used and accepted.

Furthermore, efficacy can be measured via several different methods, and a surgeon’s self-reported improved ability to precisely and accurately use their sinus instrumentation to safely complete the procedure is a valuable added benefit. For example, in one retrospective study, although complication rates with and without surgical navigation were comparable, cases performed with navigation had more sinuses entered. This would be an important consideration for in-office procedures, where typical surgical techniques to improve visualization and access may be limited due to patient discomfort. Therefore, though evidence demonstrating improved outcomes with surgical navigation is lacking, it has numerous apparent benefits.