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Surgical Issues: Insights into UPPP, CPAP Use, and CSF Leaks
From: ENT Today, August 2008
by Pippa Wysong
ORLANDO, FL-Does multilevel upper airway surgery preclude continuous positive airway pressure (CPAP) usage, and is there a best way to repair cerebrospinal fluid (CSF) leaks? These are among the questions into which researchers provided insight at the recent Combined Otolaryngology Spring Meeting here.
UPPP Patients Can Still Use CPAP
In one surgery-related talk, researchers showed that a history of uvulopalatopharyngoplasty (UPPP) does not preclude the use of CPAP in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS). In fact, one study now suggests that patients who have had surgery, yet who have persistent symptoms, can still benefit from CPAP, and may even use lower pressures than were used prior to surgery. Compliance can be improved, too.
This was the finding of a study designed to investigate whether multilevel upper airway surgery precludes CPAP usage in patients. Details were presented at a session of the Triological Society section of the conference. The primary author of the study was Michael Friedman, MD, Professor of Otolaryngology-Head and Neck Surgery at Rush University Medical Center in Chicago; presenting was Rohit Soans, MD, a research fellow at Rush University.
There are a few myths about surgery and CPAP that seem to be common in the field of otolaryngology. The first is that surgery does not help in obstructive sleep apnea. The second is that if surgery fails, you cannot use CPAP again. And third, CPAP compliance is drastically altered by surgery, said Dr. Soans.
The study also investigated whether surgery affected CPAP pressure settings needed by patients, as well as CPAP compliance. A retrospective review was done of 300 patients who had undergone multilevel upper airway surgery for moderate to severe OSAHS. Of these patients, a total of 52 had returned with persistent symptoms and were willing to try CPAP therapy again. They all underwent CPAP titration.
Data included preoperative and postoperative BMI, apnea-hypopnea index (AHI), rapid eye movement (REM) sleep measurements, optimal CPAP pressure settings, and details of CPAP compliance.
Preoperatively, patients had a mean BMI of 31.2, which had not changed at a six-month postoperative follow-up. AHI was a mean of 63.2 prior to surgery, and dropped to 50.1 postoperatively; the change was statistically significant. Minimum oxygen saturation increased from a mean of 71.9% preoperatively to 80.4% six months postsurgery.
These improvements are important because they represent the group that failed surgery, Dr. Friedman told ENT Today in an interview. In the medical literature, the success rate for surgical treatment of OSAHS is reported as being about 40%, he said. This number represents old studies on the efficacy of UPPP as an isolated procedure. Most patients have multilevel surgery, and the success rate is 66%.
The efficacy of the study group of 300 patients (only 52 returned with symptoms) was comparable to the results of a meta-analysis by the research group, which, in a review of 49 articles and 1978 patients, revealed that the success rate of multilevel surgery was closer to 66%, Dr. Friedman said. Over the past decade, multilevel surgery has been the standard of surgical treatment.
In addressing the second myth, that surgery precludes CPAP therapy, the researchers found that 96.2% of their patients were able to attain optimum CPAP settings. Preoperatively, the optimal CPAP pressure was a mean of 10.6 cm H2O, whereas six months postoperatively, the mean was 9.8 cm H2O. The difference was of borderline statistical significance (p < 0.05).
As for compliance, postsurgery, the patients actually had improved CPAP compliance. Preoperatively, none of the 52 patients had used CPAP for more than four hours per night, whereas close to half of them used CPAP for at least four hours a night postoperatively.
The perception that surgery precludes the use of CPAP therapy is based on a study in the medical literature that was based on 13 patients who had undergone UPPP, and who were compared to 13 controls. CPAP titrations were performed on patients who were awake and sitting up. Dr. Friedman added that he believes any study on CPAP compliance must be done with the patient asleep.
The results from that study concluded that patients could not reach the maximum of 20 cm of water and that the compliance may also be reduced in these patients. The main critique of that study is that it was focused on maximum pressures and not optimal CPAP pressures, Dr. Soans said in the talk.
Another problem that can occur is air leak at optimal pressure, but in some patients this can be fixed with use of a full face mask. Still, for patients who still need help after surgery for OSAHS, CPAP may be the ticket.
-Michael Friedman, MD
CSF Otorrhea Study
In a second talk on surgical matters, Joe W. Kutz, MD, Assistant Professor of Otolaryngology at the University of Texas Southwestern Medical Center in Dallas, described different ways in which CSF leaks can be repaired.
He pointed out there are several possible causes for CSF leaks. One proposed etiology is aberrant arachnoid granulations. It's been long known that arachnoid granulations can be aberrant along the middle fossa floor. Through years of pulsations, arachnoid granulations can cause a fistula between the subarachnoid space and into the air-containing space of the mastoid or middle, resulting in cerebrospinal fluid otorrhea or rhinorrhea, he said.
Some patients may have conditions which cause increased intracranial pressure, such as benign intracranial hypertension, obstructive sleep apnea, or obesity. Recurrent meningitis is the most significant complication from persistent CSF leakage, and surgery is often the only treatment, he said.
The intent of surgery is to prevent further leakage, but, more importantly, to re-establish the barrier between the subarachnoid space and the mastoid or middle ear, he said. Key surgical approaches include the transmastoid approach, middle fossa craniotomy, or a combination of the two. Different materials are commonly used for the repair of the defects.
Researchers conducted a retrospective study to compare different groups of patients who presented with spontaneous CSF otorrhea, and to compare autologous materials to bone cements used in the repairs.
A total of 17 patients who had undergone 19 surgeries met inclusion criteria. The patients had a mean age of 60; 12 were female, and five were male. All the female patients were obese (body mass index [BMI] greater than 30), whereas only two of the male patients were obese.
Fifteen patients underwent CT scans, MRI was performed on 12, and eight patients required MRI cisternography to confirm the location of the defect. Defects were most commonly found in the tegmen mastoideum and the tegmen tympani. There was a mean follow-up of 11 months.
As for the surgical approach, 14 underwent middle fossa craniotomy, and three had a transmastoid craniotomy (two were for posterior fossa defects, one for an isolated tegmen mastoideum defect). Two patients underwent a combined approach.
Nine different materials were used in the various surgeries, and were selected based on surgeon preference. Bone cement was the most common material used, and was utilized in 11 of the surgeries. Temporalis fascia was used in 10 of the surgeries.
Most surgeons used two materials, with an average of 2.7 materials used per case. The most materials used in a single operation were five, Dr. Kutz said.
Bone cement has certain advantages. For one, there's no need to obtain autologous materials, he said. In addition, bone cement can be used to cover large areas, and is easy to apply. The disadvantages include infection, a potential for conductive hearing loss, and the possibility of reabsorption with time-although studies suggest bone cements hold up well over time, he said.
However, both autologous materials and bone cements were found to be equally efficacious in the study population. And the approach that we advocate for most cases is a middle fossa craniotomy, he said.
©2008 The Triological Society