Simple Predictors of Uvulopalatopharyngoplasty Outcome in the Treatment of Obstructive Sleep Apnea

Richard P. Millman, MD, Carol C. Carlisle, RN, Cynthia Rosenberg, DDS, Douglas Kahn, DO, Robert McRae, MD, and Naomi R. Kramer, MD
Departments of Medicine, Otorhinolaryngology, and Plastic Surgery, Brown University School of Medicine, Providence, RI
Published in Chest, 118(4):1025-1030, 2000

Summary

To see whether various preoperative measures related to sleep apnea could predict the outcome of surgical treatment, the authors looked at records of 46 patients who had undergone the common procedure called uvulopalatopharyngoplasty (UPPP) - removal of the uvula and back of the soft palate, often accompanied by tonsillectomy.

The preoperative measures examined were:

1. Sleep polysomnography (all-night laboratory study of brain waves, breathing, heart rhythm, arterial blood oxygen, muscular tension, and eye and leg movements);
2. Cephalometry, the measurement of various dimensions of the head relating to the jaw and airway, based on x-ray;
3. Anthropometry, the measurement of various dimensions of the body, in this case limited to the Body Mass Index (weight measured in kilograms divided by body surface area measured in square meters), an index of obesity.

As a group, these patients were predominantly male (94%), middle-aged (averaging 43 years of age), obese (average Body Mass Index = 32 kg of weight per square meter of body surface), and affected by a moderate to severe degree of sleep apnea (average Apnea Hypopnea Index or AHI of 45 respiratory related arousals per hour of sleep; average lowest blood oxygen saturation of 81%).

Surgery was rated a success if it reduced the AHI to within the plausibly normal range (less than 10 respiratory arousals per hour of sleep) or to less than 20 (still diagnosable as mild sleep apnea) if it decreased the AHI by at least half.

These criteria attributed success to only 16 of 46 patients operated on--35%. By a more stringent criterion for success, only 18% achieved a postoperative AHI less than 10.

The majority of patients reported snoring less after surgery; half reported less daytime sleepiness. As a whole, the group showed no significant weight change with surgery.

Factors predicting which of the patients showed this improvement included:

1. Presurgical AHI less than 35, indicative of mild to moderate apnea. These 24 patients had a 50% success rate, in contrast to success for only 18% of the 22 patients with more severe disease.
2. Distance from the mandible (lower jaw) to the hyoid bone in the neck of less than 20 mm, an indication of a greater length of the airway.
3. Absence of retrognathia (a receding chin). The majority (65%) of patients did have retrognathia, and these had a 27% success rate, while the 16 patients without retrognathia had a 50% success rate.

All other measurements failed to add predictive power, including age, obesity, lowest oxygen saturation, and other measurements of the head.

The authors noted that the success rate for their patients (35%) approximated that reported (41% success) in a review of studies of UPPP outcome that used similar criteria for success. Studies of predictive factors have yielded variable results, but at least some have shown findings consistent with those of this study.

The authors concluded that certain characteristics of patients should warn against proceeding with surgery, at least with the UPPP procedure alone. Such patients might benefit more from surgery with the addition of procedures like genioglossus advancement.

Comments

In addition to the points emphasized by the authors, I note that:

1. Of those measures that predicted surgical outcome, only the measurement of the distance between the jaw and the hyoid bone in the neck yielded a very small group of 12 patients who had a respectable rate for surgery of 75%. The other two predictors--less severe apnea and absence of receding chin--yielded groups with a still disappointing success rate of 50% for surgical treatment. This suggests that the UPPP alone is appropriate for only a small fraction of apnea patients.
2. Those patients who underwent surgery were said to have "refused nasal continuous positive airway pressure or had tried it and not been able to tolerate it." Refusal without trial must be viewed with skepticism as inadequate justification for surgery; a few weeks on CPAP, an entirely reversible and benign intervention, might make a good prerequisite to consideration for surgery, since it is reasonable to ask a person to try such a important and harmless treatment before refusing it. Also, the reasons for inability to tolerate CPAP are left unstated, and probably include many instances of potentially soluble problems (such as air leaks) for which no plausible solution was ever tried.

Although I don't seriously doubt the validity of the authors' findings, the reader should be aware that the group of patients studied represented a highly selected minority (less than half) of all patients undergoing surgery for obstructive sleep apnea at the institution during the time period (1990-1999) under study. What this might mean is some selection bias that, for example, removed patients who had no follow-up polysomnography. Though the reason for this exclusion seems obvious and necessary, it remains possible that patients who received no follow-up studies more often had excellent results that seemed to require no such follow-up examination. In other words, the requirement for postsurgical polysomnography may have removed a disproportionate number of surgical successes.

"I have never taken any exercise except sleeping and resting."
Mark Twain

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