Clinical Practice Guideline
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
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,
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
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
Information for Waiver submission.
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%.
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.
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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 2nd, 2007 at: http://www.faa.gov/about/office_org/headquarters_offices/avs/offices/aam/ame/guide/app_process/exam_tech/item27/
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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.
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March 19, 2007