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Wednesday, January 26, 2011

TransOral Robotic Surgery (TORS) for Obstructive Sleep Apnea

Surgeons with the Department of Otorhinolaryngology-Head and Neck Surgery at Penn are investigating the use of transoral robotic surgery (TORS) to treat lingual tonsillar hypertrophy in patients with obstructive sleep apnea (OSA).

Lingual tonsil hypertrophy (LTH) has been recognized as a contributor to the pathology of OSA for at least a decade and is thought to be an explanation for the variable efficacy of uvulopalatopharyngoplasty (UPPP) and other surgical treatments for OSA.

The addition of lingual tonsillectomy to these procedures has been shown to ameliorate OSA in a majority of patients. However, tongue base surgery is identified with a variety of challenges, including the difficulty of manipulating surgical instruments in a limited operative field, compromises in lighting and visualization with endoscopic instruments (including lack of depth perception), and occasionally, the need for concomitant tracheotomy and/or other external incisions during surgery.

To address these limitations, investigators at Penn have initiated a clinical trial that combines traditional surgery with transoral robotic surgical techniques first developed within the Penn Department of Otorhinolaryngology-Head and Neck Surgery.

TORS offers surgeons improved dexterity and precision, advanced imaging techniques with three-dimensional depth perception and fewer limitations within the operative field than traditional or laparoscopic surgery. When used to perform lingual tonsillectomy, TORS permits removal of obstructive tissue in the tongue base and the potential to obviate the need for external incisions, pharyngotomy and tracheotomy.

The primary objectives of the current study are to assess the efficacy and outcomes of LTH resection using the combination of traditional surgery plus TORS in patients with tongue base level obstruction causing sleep apnea.

Patients are assessed through in-office examination and review of recent sleep studies, MRI of the neck, and sleep endoscopy. The latter is a minor procedure in which the patient has sleep induced by an anesthesiologist and is then evaluated with a scope to identify the levels of tissue obstruction.

If the tongue base is involved, the patient is considered a candidate for TORS for sleep apnea. The TORS sleep apnea procedure involves surgery and an average hospital stay of just under three days. During the first 36 hours post-surgery, the patient may require an endotracheal tube to protect against breathing difficulties. Duration of stay is dependent upon the patient’s recovery in terms of pain tolerance and reduction of soft tissue swelling.

Full recovery is expected to take about three weeks. A post-surgical sleep study is obtained three months after surgery.

Case Study

Mr. G, a 47-year-old male with a diagnosis of obstructive sleep apnea, was referred to the Department of Otorhinolaryngology-Head and Neck Surgery at Penn for evaluation. With the exception of moderate obesity (BMI 32), Mr. G’s medical history at presentation was unremarkable. He was taking no daily medications or other treatments for OSA.

Following his diagnosis, he had tried to use continuous positive airway pressure, but found the mask uncomfortable and soon became noncompliant. Mr. G had discussed stand-alone uvulopalatopharyngoplasty with an oral surgeon as an alternative to CPAP, but was discouraged by the potential lack of long-term efficacy.

At Penn, fiberoptic nasopharyngoscopy revealed hypertrophic lingual tonsils obstructing the airway in addition to palatal obstruction. After a consultation with his personal physician and a consideration of the risks and benefits of transoral robotic surgery, Mr. G agreed to become a participant in the TORS sleep apnea study.

Surgery involved both UPPP and tongue base resection using TORS (Figure 1). The tongue base resection resulted in removal of the same volume of tissue as was removed with the UPPP, producing substantially greater airway than would be achieved with UPPP alone.

Mr. G was extubated at the end of the procedure and had a relatively short hospital stay of 72 hours.

At a follow-up visit three months after his surgery, Mr. G reported substantially improved OSA symptoms, including fewer night-time awakenings and diminished snoring.

Anesthesia Research in TransOral Surgery for Sleep Apnea

Researchers in the Department of Anesthesiology and Critical Care at Penn Medicine have developed a pharmacokinetic algorithm for the rapid titration of propofol during sleep nasoendoscopy when inducing moderate obstruction in the diagnosis of obstructive sleep apnea (OSA).

A short-acting, intravenously administered hypnotic known to cause obstruction at the soft palate and epiglottis during sedation, propofol is useful as a means to identify the anatomic site of airway obstruction in patients with OSA.

Identification of the site of obstruction is key to determining the medical and surgical course of treatment. The ability to reliably achieve the correct level of sedation and maintain moderate obstruction can be challenging, however.

Total obstruction with hypoxia is common, and measures such as jaw thrust and bag-mask ventilation make observation of the anatomic site of obstruction difficult. To address these concerns, Penn researchers developed a pharmacokinetic approach using rapid titration to moderate obstruction as the endpoint.1

Methods –
This was a prospective study of screening sleep nasoendoscopy performed in 100 patients for an experimental transoral robotic tongue base reduction. Pharmacokinetic software was used to calculate the infusion rate and pause interval (during which the syringe pump is stopped) necessary to maintain the desired level of obstruction.

All cases were performed in an OR with 2 LPM O2 oral canula. A nasopharyngeal laryngoscope was passed into the velopharynx and the induction sequence initiated. The target was considered the first instant of observed obstruction. The infusion was discontinued when adequate video confirmation of anatomic site was complete. To date, 15 patients have been evaluated.

Results –
In all patients, stable moderate obstruction was produced permitting identification of the anatomic site of obstruction. In all patients except one, the endpoint of obstruction was obtained with the specified infusion sequence. The software was modified after this study to increase the target of the second infusion from 95% to 99%. All other patients have achieved obstruction during the interval of 90 – 390 seconds.

Conclusions –
Titration of propofol to precise pharmacodynamic endpoints shows promise in simplifying challenging tasks such as sleep nasendoscopy. The proposed system employs an anesthesiologist in the loop for titration and may address present concerns with target-controlled infusion in clinical practice.

1. Mandel JE. A pharmacokinetic approach to rapid titration of propofol to moderate obstruction for diagnosis of sleep apnea. Presented at the 19th Annual Meeting of the International Society of Anesthetic Pharmacology, October 2010, San Diego, CA.

Team of Faculty

The Department of Otorhinolaryngology-Head and Neck Surgery at Penn Medicine is actively involved in research, including investigations of the efficacy and safety of TransOral Robotic Surgery (TORS) in a variety of indications.

TORS was invented and developed at Penn Medicine by the pioneering team of Gregory S. Weinstein, MD, and Bert W. O’Malley, Jr., MD.

Performing TransOral Robotic Surgery for OSA at Penn Medicine

Bert W. O’Malley, Jr., MD
Gabriel Tucker Professor and Chair,
Department of Otorhinolaryngology - Head and Neck Surgery

Gregory S. Weinstein, MD, FACS
Professor and Vice Chair,
Department of Otorhinolaryngology - Head and Neck Surgery

James J. Kearney, MD
Associate Professor of Otorhinolaryngology - Head and Neck Surgery

Erica R. Thaler, MD
Director, Division of General Otolaryngology
Professor of Otorhinolaryngology-Head and Neck Surgery


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