Clinical Practice Guideline

for

SINUSITIS

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Developed for the

Aerospace Medical Association

by their constituent organization

American Society of Aerospace Medicine Specialists

________________________________________________________________________

Overview. There are four paired (paranasal) sinuses in the human skull: the frontal, sphenoid, ethmoid, and the maxillary sinuses which are named for the region of the skull for which they inhabit. The exact reason for the presence of these paranasal sinuses is not known. However, the presence of these sinuses decreases the weight of the skull, helps to moisten the air entering the nasal cavity, and can act as a “crumple zone” in trauma to the skull like the bumper of an automobile. They also act to add resonance to the human voice.

The paranasal sinuses are lined with ciliated respiratory epithelium and this epithelium is innervated and vascular. Mucus is moved by the ciliary component of the respiratory epithelium to the ostia or “windows” by which these paranasal sinuses communicate with the nasal cavity. These ostia interact and communicate with the nasal cavity through an important structure called the osteomeatal complex. Structural abnormalities, inflammation, or nasal polyps may interfere with proper nasal mucociliary clearance mechanisms at the osteomeatal complex and lead to the development of infection or rhinosinusitis. Air should properly be able to flow freely between these paranasal sinuses and the nasal cavity. This would be especially important in atmospheric pressure perturbations such as would be confronted in flying and diving situations.

Inflammation of the nose and paranasal sinuses is called rhinosinusitis. The causes of rhinosinusitis are many and include viral, bacterial, allergic, chemical, and fungal causes. Trauma, foreign bodies, and immunologic disabilities, odontogenic causes, cystic fibrosis, and gastroesophageal reflux may also be present as causes of rhinosinusitis.

The most common variety of rhinosinusitis is viral and is seen at a staggering rate. It is estimated that one out of ten people in the United States has some form of rhinosinusitis. Over one billion episodes of sinusitis occur annually. The medical costs to the United States are enormous. There are over five billion dollars spent each year in doctor’s office visits and pharmaceutical costs, mostly antibiotics. The impact on the community due to lost work performance and absenteeism is incalculable. Another sixty billion dollars is spent each year on surgical corrections of sinus-related problems such as chronic rhinosinusitis.

Rhinosinusitis can be acute if it lasts less than four weeks. The most common etiologic agents of acute bacterial rhinosinusitis are Streptococcus pneumoniae and Haemophilus influenza in adults. Both of these bacteria can cause acute rhinosinusitis in children along with Moraxella cattarhalis. Should acute bacterial rhinosinusitis last longer than four weeks but less than six weeks it is called acute refractory rhinosinusitis.

Recurrent acute rhinosinusitis is seen in individuals who experience at least four episodes a year with symptom free intervals. Infections lasting longer than three months are classified as chronic rhinosinusitis. Chronic rhinosinusitis may be further divided into chronic persistent and chronic recurrent varieties, the latter of which often requires numerous antibiotic courses to help manage it.

As always a careful history and physical examination is performed for the patient with rhinosinusitis. Laboratory and plain-film radiological studies can be of aid in the diagnosis of this disorder. Plain film-radiography (Water’s, Caldwell, and lateral views) has a sensitivity and a specificity of seventy-six and seventy-nine percent respectively but the false negative rate can be upwards of forty percent. Computerized axial tomography or the CT scan has even higher sensitivity but may cause a large false positive rate in diagnosing rhinosinusitis.

Recent meta-analyses of double-blind, placebo controlled, randomized clinical trials performed by the Cochrane Commission have shown that four clinical criteria can be extremely helpful in diagnosing acute rhinosinusitis. The presence of unilateral pain and pressure sensation within a paranasal sinus, mucopurulent mucus secretions from one nare (unilateral), mucopurulent secretions from both nares (bilateral), and the direct visualization of mucopurulent secretions in the nasal cavity can aid the physician in diagnosing acute bacterial rhinosinusitis. The presence of three out of four of these criteria can point toward acute bacterial rhinosinusitis with a

sensitivity and a specificity identical to that of plain-film radiography at seventy-six and seventy-nine percent.

The use of CT scans should probably be reserved for those patients not responding to proper therapy and for those for who surgery is being considered as a treatment option. The “gold standard” in diagnosis, the sinus puncture with aerobic and anaerobic cultures, is not available in most offices and thus is not practical.

Aeromedical Concerns. For the vast majority of patients acute or chronic sinusitis is problematic only for discomfort. In fact, chronic sinusitis may only be minimally symptomatic at ground level. However, perturbations of atmospheric pressure as seen in the aviator or scuba diver may develop sudden, incapacitating pain. This phenomenon is called barotraumatic sinusitis, sinus “block” or “squeeze”. This event can occur on ascent but usually occurs on descent. Should that event occur immediately prior to or during landing procedures in the aviator, it could lead to an aircraft mishap. This is a flight safety issue and can threaten the life of the pilot and his passengers. The current recommendation is that no aviator fly with a “cold” or viral upper respiratory tract infection, or with the condition of rhinosinusitis. The aviator should be considered grounded until he or she is off medications and has had complete resolution of the condition. Acute barotraumatic sinusitis is preventable by keeping the patient grounded until complete resolution. Should a pilot or aircrew member experience difficulty on descent topical oxymetazoline could be used to decrease symptomatology and get him or her “down”. Primary prevention is quite simple: “No flying with a URI or rhinosinusitis”.

Treatment: Of all the acute rhinosinusitis present, only one-half to two percent is complicated by bacterial involvement. The predominant cause is, as previously mentioned, viral in nature. Despite this, the vast majority of patients have historically received an antibiotic prescription from a well-meaning physician in an attempt to “cure” what is most likely acute viral rhinosinusitis. This has been, for the vast majority of patients, useless, enormously expensive, and has caused an ever-increasing amount of antibiotic resistance in the commensual bacterial that inhabit the paranasal sinuses.

Randomized clinical trials have shown there to be a benefit to prescribing antibiotics only for those acute rhinosinusitis episodes that meet the Cochrane Criteria as described above. The vast majority of acute rhinosinusitis can be managed using decongestants such as topical oxymetazoline or systemic medications such as pseudephedrine (alpha constrictors) which act to shrink the nasal mucosa thus aiding in mucociliary clearance. Mucolytic agents such as guaifenesin or saline nasal irrigations act to decrease the viscosity of sinus secretions and likewise aid, by this different mechanism, to help proper mucociliary clearance occur. Analgesic medications help with the discomfort confronted by patients with this disorder such as acetaminophen.

Antihistamines, while helpful for seasonal allergic rhinitis, can actually worsen acute rhinosinusitis by causing thickening of sinus secretions leading to inspissation of the secretions behind the osteomeatal complex. This can lead to acute bacterial rhinosinusitis. Nasal corticosteroids, also helpful for seasonal allergic rhinitis, are not thought to be helpful or curative for acute bacterial rhinosinusitis. Should antibiotics be considered for the management of acute bacterial rhinosinusitis, the selection can be guided by using first-line or second-line agents. For the patient who has not had a recent antibiotic and who lives in a community with lesser levels of antibiotic resistance, a first-line drug is appropriate such as ten to fourteen days of amoxicillin or amoxicillin with clavulanate. For the beta-lactam allergic patient, the choice of trimethoprim-sulfamethoxazole, clarithromycin, or azithromycin is also appropriate.

For individuals who live in communities with higher levels of antibiotic resistance profiles, or who have recently been given antibiotics for any reason, or who have failed a recent course of antibiotics for their rhinosinusitis, the use of a second-line agent is appropriate such as amoxicillin with clavulanate, the newer flouroquinolones, cefpodoxime, or cefuroxime. Should a patient fail a second-line agent, the patient may be diagnosed with chronic bacterial rhinosinusitis. In that case, the patient should be given “maximum medical treatment”. This consists of six weeks duration of a broad-spectrum antibiotic (one of the second-line agents), oral decongestants, mucolytic agents, and saline nasal sprays and or irrigations. The bacteria likely to cause this condition are Staphylococcus aureus, bacterioides species, and gram negative enteric organisms.

Should this “maximum medical treatment” fail, a CT scan should be performed as well as the consultation of an otolaryngologist. The otolaryngologist will review the CT scan and examine the patient and determine if surgery is indicated, perhaps due to some abnormality in the osteomeatal complex (OMC). If present, the current surgical procedure thought best is that of the functional endoscopic sinus surgery where abnormalities at the OMC can be corrected leading to proper mucociliary clearance. While not “curative” per se, the vast majority of patients with chronic rhinosinusitis will improve. Infectious disease consultation and surgical involvement may also be required for that of mucor, or invasive fungal rhinosinusitis.

Information for Waiver submission. A viral URI or episode of acute bacterial rhinosinusitis requires no waiver. However, should a patient develop chronic rhinosinusitis that patient should be grounded. The patient should receive “maximum medical treatment” to see if the condition resolves. If so, that patient may be returned to flying duties. If not that patient should have a CT scan and be seen by an otolaryngologist. That patient may require functional endoscopic sinus surgery.

Once the surgery, if indicated, has been performed and the patient completes a convalescent period, that patient may be tested in an altitude chamber for symptoms. Should he or she have no symptoms, a waiver can be submitted to the governing body for consideration of returning that aviator to the cockpit. This aeromedical disposition will be made on the basis of a waiver that the flight surgeon or aviation medical examiner submits on that aviator including history, physician examination, laboratory, radiological, consultant input data, and how that individual performed during the altitude chamber evaluation. A waiver is required for chronic sinusitis, especially for those requiring surgical intervention. In the military, an initial waiver may be granted if the patient exhibits no symptoms of recurrence for one year. .

The requirements for civil medical certification are pretty much the same as for the military. Most airmen do not report an acute episode of sinusitis to their Aviation Medicine Examiner (AME). Should they present for their examination during an acute attack, they should be deferred medical certification until they complete treatment.

Civil airmen with chronic rhinosinusitis will not likely gain medical certification.

Medications that are used to “clear” a sinus are permitted in civil aviation (oxymetazoline, pseudoephedrine, nasal steroids, and nasalcrom).

Experience: As stated above, most of these cases resolve spontaneously or with conservative therapy. Of those more complicated cases requiring a waiver, most are allowed to return to aviation duties. In the US Air Force, a total of 37 cases were submitted for waiver from Sep 2001 to Feb 2007. All except four of these cases were approved for a waiver for an acceptance rate of 89%.

References:

Air Force Instruction 48-123, Attachment 7 (MEDICAL STANDARDS FOR FLYING DUTY). This is published by the United States Air Force and is available online at http://brooksidepress.org/Products/OperationalMedicine/DATA/operationalmed/Instructions/48123.pdf as of March 2007. Published in 2006. pp 157-159.

Citardi MJ. Brief overview of sinus and nasal anatomy. Published by the American Rhinologic Society. Electronic version available at http://www.american- rhinologic.org/patientinfo.sinusnsasalanatomy.html, 2006. pp 1-2.

DeHart RL, Davis JR. Fundamentals of Aerospace Medicine-Third Edition. Published by Lippincott Williams and Wilkins. 2002. pp 420-427 and 453-469.

Garau J, Dagan R. Accurate diagnosis and appropriate treatment of acute bacterial rhinosinusitis: minimizing bacterial resistance. Clinical Therapeutics. Volume 25, issue 7, July 2003: pp 1936-1951.

Guide for Aviation Medical Examiners. Published in the Code of Federal Regulations/Medical Standards (14 CFR 67.111), section 27 on Sinuses. This is available online as of March 2^nd, 2007 at: http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/exam_tech/item27/

Lau J, Zucker D, Engels EA, Barza M, Terrin N, Devine D, Chew P, Lang T, Liu D. Diagnosis and Treatment of acute bacterial rhinosinusitis. Evidence Report Technology Assessment (summ) 1999 Mar; (9): pp 1-5.

Mafee MF, Tran BH, Chapa AR. Imaging of rhinosinusitis and its complications: plain film, CT, and MRI. Clinical Review of Allergy and Immunology. 2006 Jun; 30 (3): pp 165-186.

McQueen WJ, Santiago-Marini J. Chapter 6: The Otolaryngological Aspects of Aerospace Medicine. Published in the Flight Surgeon’s Handbook by Brooks Air Force Base, 1998. Electronic version available at http://www.brooks.af.mil/af/files/fsguide/HTML/Chapter_06.html:pp 1-15.

Merenstein D, Whittaker C, Chadwell T, Wegner B, D’Amico F. Are antibiotics beneficial for patients with sinusitis complaints? The Journal of Family Practice. February 2005; vol. 54 (2): pp 152-163.

Nudelman J. How should we treat acute maxillary sinusitis? American Family Physician. Volume 64/ No. 5. September 2001: pp 837-840.

Pichichero ME, Brixner DI. A review of recommended antibiotic therapies with impact on outcomes in acute otitis media and acute bacterial sinusitis. The American Journal of Managed Care. August 2006, Supplement Content, pp S292-303.

Rayman R, Hastings J, Levy R, Pickard J. Clinical Aviation Medicine-Fourth edition. Published by Professional Publishing Group. Ltd. 2006. pp 133-146.

Spurling GK, Del Mar CB, Dooley L, Foxlee R. Delayed antibiotics for symptoms and complications of respiratory infections. Cochrane Database Systematic Review, 2004. Oct 18; (4): CD004417.

Winstead W. Rhinosinusitis. Primary Care Clinical Office Practice. Volume 30; Mar 2003: pp 137-154.

March 19, 2007