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Communications to the Editor |

Objective Evaluations of the Results of Treatment for Snoring and Sleep ApneaResponse FREE TO VIEW

Thomas J. Kehoe, MD, FCCP
Author and Funding Information

Affiliations: Charles Z. Weingarten, MD Evanston Hospital Evanston, IL ,  Head and Neck Surgery Stanford University Center for Excellence in Sleep Medicine Palo Alto, Ca



Chest. 1999;115(1):305-307. doi:10.1378/chest.115.1.305
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The study by Powell et al (May 1998),1 evaluating multiple parameters subsequent to radiofrequency treatment of the soft palate in patients with sleep-disordered breathing, was well designed and comprehensive in scope. Currently, the only approved application for Somnoplasty (Somnus Medical Technologies, Inc; Sunnyvale, CA) is for the treatment of snoring, although evaluation of its use for the treatment of obstructive sleep apnea is implied and noted as a secondary objective of the study. As correctly noted in the excellent editorial by Loube, this study measures subjective outcomes, except for the documentation of sleep and palatal shrinkage in the short term. The primary approved purpose of Somnoplasty is the reduction of snoring, which cannot and is not accurately assessed by patients or their bed partners, particularly on a night-to-night basis.

As Loube states, “… we must develop and apply standardized, objective measures to assess adequacy of snoring improvement.”2 Loube also expresses concern that patients with obstructive sleep apnea (OSA) who receive surgical intervention for snoring may remain inadequately treated for OSA. A system does exist that addresses both of these concerns and is commercially available from SNAP Laboratories LLC (Glenview, IL). The SNAP system collects sounds of respiration as well as snoring via an oronasal cannula. Data are recorded and analyzed at SNAP Laboratories. Their analysis includes information regarding apnea and hypopnea, as well as an extensive analysis and documentation of snoring. Parameters include spectral profiling and incidence by spectral category, as well as amplitude determination relative to the patient’s quiet respiration.

One study has documented the system’s ability to accurately detect and characterize snoring, as well as apnea.3The spectral profiling of snoring, as performed by the SNAP system, has been demonstrated to document changes subsequent to palatal reduction surgery (ie, uvulopalatopharyngoplasty, laser-assisted uvulopalatopharyngoplasty, uvulopharyngoplasty).4 Findings indicate that patients with upper airway resistance syndrome tend to develop obstructions at the level of the palate more frequently than OSA patients.5 Spectral analysis of snoring frequencies assists in identification of the most likely sites of sound generation and airway compromise. Clearly, the ability to objectively evaluate the results of Somnoplasty or any other treatment for snoring and apnea is now available and should be used to assess the effectiveness of this therapy.

Correspondence to: Thomas J. Kehoe, MD, FCCP, Evanston Hospital, 2650 Ridge Ave, Evanston, IL 60201

Powell, NB, Riley, RW, Troell, RJ, et al (1998) Radiofrequency volumetric tissue reduction of the palate in subjects with sleep-disordered breathing.Chest113,1163-1174. [PubMed] [CrossRef]
 
Loube, D Radiofrequency ablation for sleep-disordered breathing.Chest1998;113,1151-1152. [PubMed]
 
Weingarten, CZ Snare uvulopalatoplasty.Laryngoscope1995;105,1033-1036. [PubMed]
 
Walker, RP, Gatti, WM, Poirer, N, et al Objective assessment of snoring before and after laser-assisted uvulopalatoplasty.Laryngoscope1996;106,1372-1377. [PubMed]
 
Loube, DI, Andrada, T Upper airway resistance syndrome patients increase resistance at the level of the velopharynx during sleep [abstract]. Chest. 1997;;112 ,.:9S
 
To the Editor:

I was pleased that the original article on radiofrequency to the human palate was accepted and published in CHEST.1-1 However, the initial editorial comments by Dr. Loube1-2 were a disappointment. He focused on subject matter such as laser-assisted uvulopalatopharyngoplasty manufacturing devices, Food and Drug Administration strategy, and snoring. It was very curious that he would use this paper as a forum to expound on such issues, since I had not mentioned or even vaguely suggested that the paper might primarily address these issues. The primary objectives of this investigation were centered around feasibility and safety of radiofrequency in the upper airway of the human model.

This investigation was never designed to investigate a new treatment for snoring, as the surgical literature is replete with adequate remedies for this problem. The palate study was the second in a series of four individual studies to evaluate the possible uses of radiofrequency energy to shrink the soft tissues of the upper airway in obstructive breathing disorders. The primary study objectives were clearly defined in this paper and were to evaluate pain, swallowing, edematous response, tissue shrinkage, sleep, and safety. The possible effect on snoring was a secondary objective. I reported the data of the clinical outcomes on all objectives studied. It is unfortunate that outcomes concerning snoring became such a focus, since it has distracted some readers from the primary outcome goals of this study. Because this technology had never been used in the airway, each subject was advised that our primary objectives were those listed, and that snoring was incidental to these objectives except as an end point. If this investigation revealed favorable outcomes concerning our primary objectives, regardless of snoring outcomes, then advancement to the final protocol investigation for treatment of the tongue base in humans would start. If adverse effects, or a poor acceptance of this treatment, were identified, then the planned future studies would either be delayed or would not proceed.

It appears I have failed to clearly present these facts in this paper, or perhaps those who wish to be critical are not reading the entire paper. A case in point is the letter of Kehoe and Weingarten. The authors recommend the use of a technology (SNAP Laboratories LLC; Glenview, IL) to document and characterize snoring and apnea. How could these respondents have missed a very lengthy discussion of the rationale for not including objective snoring methodology in this paper? Ten of the 61 references cited in the paper addressed this specific issue.1-1 First, it was not used because, at the time of this investigation, there was no validated objective method to accurately assess snoring. Second, since this metric was only a secondary goal, we used a subjective, previously validated visual analog scale filled out by the subjects and their bed-partners.1-1 Certainly in all investigations, an objective outcome is preferable; however, previously accepted validated methods should be used.

In a letter of three paragraphs, one entire paragraph concerns SNAP research. To my knowledge, this technology has not been validated for snoring or for accuracy of apnea or hypopnea, nor has it been approved by the American Sleep Disorders Association. Hence, for Kehoe and Weingarten to suggest that SNAP “should be used to assess the effectiveness of this therapy” seems contrary to good science. A current Medline search shows only three papers on the use of the SNAP method, including one by Weingarten3 in 1995, where he reported using a snare to snip off the uvula. He starts with 25 subjects with habitual snoring and has the subject and bed partner report on snoring levels. In the 25 subjects treated with the snare for snoring and sleep apnea, he performed 14 septal reconstructions and turbinectomies. Inclusion of nasal surgery is a major confounding factor to this study if he was attempting to objectively assess snoring outcomes using a new technique, because it is well known that changes in nasal resistance will affect the frequency and volume of snoring.4 Only 10 of 25 patients had follow-up sleep studies and only 12 of 25 had the SNAP procedure, with 8 of 12 finishing the pre- and post-SNAP studies. His study numbers were small and incomplete. An APSS abstract presented in 1995 by Rosenberg et al5 on acoustic analysis of respiration might have served as validation; however, it is difficult to accept this work without a published follow-up paper. Walker et al6 reports that the objective results from SNAP “correlated well with the subjective responses of the patients and their bed partners.” This comment seems contrary to the belief of Kehoe and Weingarten that “snoring” cannot and is not accurately assessed by patients or their bed partners.”

This appears to be the extent of the specific results of the validation studies published on this new SNAP technology. I am not aware of any validation studies comparing SNAP to polysomnograms; without these data, how can SNAP technology be used to assess sleep-disordered breathing (apnea and hypopnea)? There are additional concerns regarding the SNAP technology, including the limitation of the study time to 2 to 4 h because of the use of a Sony DAT recorder with a 2-h limit, which when extended to 4 hs may decrease the recording quality. Also, the study is performed at home without documentation of body position during sleep, and the tape must be sent to SNAP Laboratory for analysis for a cost per recording plus an additional charge per tape. This is not to say that the SNAP technology may not have a sound scientific basis and that additional published data merit validation and use. It is hoped that this summary will make it clear why we avoided technology that was not yet accepted as validated, since we ourselves were evaluating new technology.

Correspondence to: Nelson Powell, MD, Head and Neck Surgery, 750 Welsh Road, Suite 317, Palo Alto, CA 94304

References
Powell, NB, Riley, RW, Troell, RJ, et al Radiofrequency volumetric tissue reduction of the palate in subjects with sleep-disordered breathing.Chest1998;113,1163-1174. [PubMed] [CrossRef]
 
Loube, DI Radiofrequency ablation for sleep-disordered breathing.Chest1998;113,1151-1152. [PubMed]
 
Weingarten, CZ Snare uvulopalatoplasty.Laryngoscope1995;105,1033-1036. [PubMed]
 
metes, A, Ohki, M, Cole, P, et al Snoring, apnea and nasal resistance in men and women.J Otolaryngol1991;20,57-61. [PubMed]
 
Rosenberg RS, et al. Preliminary validation of an acoustic analysis of respiration during sleep. Paper presented at: APSS Meeting; 1996; Nashville.
 
Walker, RP, Gatti, WM, Poirer, N, et al Objective assessment of snoring before and after laser-assisted uvuloplatoplasty.Larngoscope1996;106,1372-1377
 

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Tables

References

Powell, NB, Riley, RW, Troell, RJ, et al (1998) Radiofrequency volumetric tissue reduction of the palate in subjects with sleep-disordered breathing.Chest113,1163-1174. [PubMed] [CrossRef]
 
Loube, D Radiofrequency ablation for sleep-disordered breathing.Chest1998;113,1151-1152. [PubMed]
 
Weingarten, CZ Snare uvulopalatoplasty.Laryngoscope1995;105,1033-1036. [PubMed]
 
Walker, RP, Gatti, WM, Poirer, N, et al Objective assessment of snoring before and after laser-assisted uvulopalatoplasty.Laryngoscope1996;106,1372-1377. [PubMed]
 
Loube, DI, Andrada, T Upper airway resistance syndrome patients increase resistance at the level of the velopharynx during sleep [abstract]. Chest. 1997;;112 ,.:9S
 
Powell, NB, Riley, RW, Troell, RJ, et al Radiofrequency volumetric tissue reduction of the palate in subjects with sleep-disordered breathing.Chest1998;113,1163-1174. [PubMed] [CrossRef]
 
Loube, DI Radiofrequency ablation for sleep-disordered breathing.Chest1998;113,1151-1152. [PubMed]
 
Weingarten, CZ Snare uvulopalatoplasty.Laryngoscope1995;105,1033-1036. [PubMed]
 
metes, A, Ohki, M, Cole, P, et al Snoring, apnea and nasal resistance in men and women.J Otolaryngol1991;20,57-61. [PubMed]
 
Rosenberg RS, et al. Preliminary validation of an acoustic analysis of respiration during sleep. Paper presented at: APSS Meeting; 1996; Nashville.
 
Walker, RP, Gatti, WM, Poirer, N, et al Objective assessment of snoring before and after laser-assisted uvuloplatoplasty.Larngoscope1996;106,1372-1377
 
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