Gil Shapira

Use of the photonic band gap fiber assembly CO2 laser system in head and neck surgical oncology

Since its introduction by Jako and Strong in 1972, the benefit of the CO2 laser systems to the head and neck surgeon has been well established in the management of early glottic, supraglottic, oral and oropharyngeal, and hypopharyngeal squamous cell carcinoma. Advantages of the CO2 laser include accuracy, predictability, and limited transmission of energy to adjacent tissues. The beam traditionally has been directed by a micromanipulator affixed to a surgical microscope coupled with a HeNe “guidebeam” to allow the surgeon to appreciate the point of laser contact. Obviously, the CO2 laser is perhaps most limited by the requirement of exposure of the site requiring laser incision. Given the transoral approach to CO2 laser procedures in head and neck surgical oncology, patients with difficult laryngeal exposure as a result of factors such as a short or stiff neck, macroglossia, retrognathia, obesity, or cervical spine immobility can severely limit the use of traditional CO2 laser systems. Traditionally, the Nd:YAG laser has maintained its use in head and neck surgery because of the capability for a flexible fiber system. However, the Nd:YAG laser is significantly more expensive than the CO2 laser and results in less control of energy dispersion to adjacent tissues. OmniGuide, Inc. (Cambridge, MA) has developed a CO2 laser system based on a flexible fiber system to deliver CO2 laser energy. This photonic band gap fiber assembly (PBFA) allows for the direct delivery of CO2 energy to regions of the head and neck in which the direct visualization required for traditional CO2 laser systems cannot be acquired. The OmniGuide Fiber is a hollow-core fiber with a dielectric mirror lining. The mirror, composed of alternating layers of high and low refractive index materials, guides the light through the fiber by reflecting it back into the hollow core. The mirror is surrounded by outer cladding that serves merely as a mechanical support to the mirror. An additional braid-reinforced polyimide jacket provides the final mechanical protection to the fiber device. The distal end of the fiber is fitted with a metal sleeve that protrudes 3 mm beyond the end face of the fiber to protect the fiber end face from tissue debris. Helium is flown through the hollow core of the fiber to allow further protection of the fiber distal tip from tissue debris, cooling of the fiber, cooling of targeted tissue, and clearing of smoke and blood from the field of sight. A gas accessory unit regulates the flow of gas into the fiber such that flow is tied to laser use. Rates of approximately 2 L/minute when the laser is idle and 8 L/minute when laser is fired were used. A Luxar LX-20SP NovaPulse (Lumenis, Yokneam, Israel) is retrofitted with an OmniGuide adapter to allow attachment of the fiber through a standard ST connector to the laser. The OmniGuide adapter couples both the laser radiation and helium flow into the fiber (Fig. 1). Fiber outer diameter of 1.8 mm allows insertion through a variety of standard malleable handpieces (Steiner hand-piece; Karl Storz, Germany; Suction Coagulator, Tyco Health Care Group, Boulder, CO), and length of 1.5 m provides maximum maneuvering ability to the surgeon. The fiber and handpiece were used transorally through a rigid endoscope. The laser was used in both superpulsed and continuous modes. Output powers ranged from 2 W for superficial tissue ablation to 8 W for precise tissue incision. We present three cases illustrating various applications of the OmniGuide flexible fiber CO2 laser system in the management of the patient with head and neck cancer. These cases include examples of diagnostic dilemma From the Department of Head and Neck Surgery (F.C.H., R.S.W.), The University of Texas M.D. Anderson Cancer Center, Houston, Texas, U.S.A.; The Bobby R. Alford Department of Otolaryngology–Head and Neck Surgery (C.N.P.), Baylor College of Medicine, Houston, Texas, U.S.A.; OmniGuide, Inc. (G.S., O.W., D.S.T., C.A., E.H.), Cambridge, Massachusetts, U.S.A.; and the Massachusetts Institute of Technology (Y.F.), Cambridge, Massachusetts, U.S.A. Editor’s Note: This Manuscript was accepted for publication February 21, 2006. Send Correspondence to F. Christopher Holsinger, MD, FACS, Department of Head and Neck Surgery, The University of Texas M.D. Anderson Cancer Center, 1515 Holcombe Boulevard, Houston, TX 77030-4009, U.S.A. E-mail: holsinger@mdanderson.org.

Gas Flow During Bronchoscopic Ablation Therapy Causes Gas Emboli to the Heart: A Comparative Animal Study

BACKGROUND Thermal ablation is one of the most commonly used modalities to treat central airway obstruction. Both laser and argon plasma coagulation (APC) have been reported to cause gas emboli and cardiac arrest. We sought to determine whether bronchoscopic ablation therapy can result in systemic gas emboli, correlate their presence with the rate of gas flow, and establish whether a zero-flow (ZF) modality would result in the significant reduction or elimination of emboli. METHODS CO(2) laser delivered through a photonic bandgap fiber (PBF) and APC were applied in the trachea and mainstem bronchi of six anesthetized sheep at varying dosages and gas flow rates. Direct epicardial echocardiography was used to obtain a four-chamber view and detect gas emboli. RESULTS The presence of gas flow accompanying APC and the CO(2) laser with forward flow correlated significantly with the appearance of gas bubbles in the atria. A definite dose response was observed between the gas flow rate and the number of bubbles seen. When the CO(2) laser was delivered through a PBF with ZF to the trachea or bronchi, no bubbles were observed. CONCLUSION Bronchoscopic thermal ablation therapy using gas flow is associated with gas emboli in a dose-dependent fashion. The use of the flexible PBF with ZF is not associated with the development of gas emboli. Further study is required to determine whether a clinically safe threshold of gas emboli exists, and the relationships among the pathologic depth of tissue destruction, gas flow, pulse duration, and the development of gas emboli.

OmniGuide photonic bandgap fibers for flexible delivery of CO2 laser energy for laryngeal and airway surgery

The CO2 laser is the most widely used laser in laryngology, offering very precise cutting, predictable depth of penetration, and minimal collateral damage due to the efficient absorption of CO2 laser by water. Surgical applications of CO2 laser in microlaryngoscopy include removal of benign lesions and early-stage laryngeal cancer. A Transoral Laser Microsurgery (TLM) approach is routinely employed for treatment of laryngeal cancer; however, the role of TLM in advanced malignant lesions remains controversial. The main limiting factor of TLM is the restrictive exposure of the endoscopes combined with the limited cutting ability offered by the existing micromanipulator, enabling cutting only along the straight line-of-sight axis. A flexible fiber delivery system offering a very high quality output beam can offer tangential cutting and can therefore significantly enhance the existing surgical capabilities. Moreover, a flexible fiber for CO2 laser delivery can be used for treatment of benign conditions through flexible endoscopy in an office setting using local anesthesia. OmniGuide Communications Inc. (OGCI) has fabricated a photonic bandgap fiber capable of flexibly guiding CO2 laser energy. Results of laryngeal in-vivo and in-vitro animal studies will be presented. We will discuss the system setup, fiber performance and clinical outcomes. In addition we will present the results of the first human treatment and highlight additional otolaryngology conditions, which will likely benefit from the new technology herein presented.