The maintenance of the office otoscope

April 2001

Office otoscopes may not be maintained properly. For optimal illumination, there should be brilliant white light not only at the tip of the otoscope speculum, but more importantly, at the focal point on the eardrum.

Otoscope bulbs should be replaced at least every 6 months and rechargeable batteries should be replaced approximately every 2 years. Otoscope bulbs can cost as much as $12 each and the rechargeable batteries are twice as expensive. When was the last time you changed them in your office?

Many expert otoscopists prefer to use the chromed steel round diagnostic otoscope head with the 3 mm or 4 mm green nylon specula.

Pediatric training programs, such as Colorado Children’s Hospital and Pittsburgh Children’s Hospital, offer excellent instruction in pneumatic otoscopy and strongly recommend the chromed steel diagnostic otoscope attachments for the house staff and attending pediatricians. These pacesetting-training programs do not recommend the more popular rectangular sliding window diagnostic otoscope attachments.

There are important problems with the black cryolite rectangular diagnostic otoscope head for several reasons. First is that the pneumatic port is only a hole drilled into the otoscope head. The male plastic adapter fits into the female port by friction. Over time the female port widens and does not permit a tight fit of the male adapter. Second, the otoscope speculum fits into a spiral groove. Over time the speculum may not fit tightly into the groove. Third, the disposable 2.5 mm black plastic aural specula are poorly designed for infant otoscopy. The permanent 3 mm black aural speculum is designed well. The disposable 2.5 mm aural specula (1/8-inch shorter and 15% reduced viewing at the speculum tip) are poorly designed for infant and young child otoscopy.

No disposable

Stan Block, MD, one of the leading pediatric practitioner researchers in acute otitis media (AOM), suggests that we “dispose of the disposables.” The 2.5 mm disposable speculum is too short and too cone shaped. Thus, the disposable specula are unable to enter deep enough into the ear canals of infants to see the tympanic membrane optimally.

The length of the straight portion of the otoscope speculum tip must be at least 6 mm before the beginning of the flared portion of the aural speculum. It is close to this in the permanent black or green nylon otoscope specula that are included in the set. The straight portion of disposable specula is only 2 mm or 3 mm. Because of this design flaw, the light beam converges approximately 0.5 cm anterior to the tympanic membrane (TM) rather than on the surface of the TM itself.

After the convergence of the light beam, it begins to flare out again and the light is diffused and dimmer than optimal. You now have made certain that the bulb and battery are working well. You have disposed of the disposables and will use the permanent aural specula for examination of young children’s eardrums.

Check the seal

The hermetic seal of each moving part of the otoscope must be checked. Any air leak will reduce pneumo-otoscopic accuracy. Is air leaking from a faulty gasket around the lens? Is air leaking where the tubing fits into the body of the diagnostic otoscope (black or chromed steel models)? And is air leaking from a poor fit between the tip of the speculum and the canal wall?

The first two air leaks may require the company to fix the problem. Pressing the child’s tragus against the straight portion of the speculum to make a better seal can stop leaks at the tip of the aural speculum. Another method is to cut about 2 mm of rubber tubing that can act as a sealing gasket at the distal part of the otoscope speculum. Or, use a larger aural speculum or commercially available (Welch-Allyn) black rubber tipped aural speculum (soft-spec) manufactured for that purpose.

Whenever the diagnostic otoscope head falls to the floor, the chromed steel head may warp “out of round” making it difficult to attach to the otoscope speculum. It can be put in round by the factory maintenance department.

Condensed moisture on the inner side of the magnifying lens can reduce vision and may require use of an anti-fogging solution or liquid soap wiped on the inside of the lens. It is easier to deal with this problem with the chromed steel diagnostic otoscope head than with the black rectangular sliding lens model.

After several years of use, some of the individual fiberoptic strands in the diagnostic otoscope head may fracture with frequent use. When several bundles of optical glass strands are fractured, there will be less light transmitted through the aural speculum and on to the eardrum. If the light is not brilliant after changing the bulb and battery, this may be the problem. Hopefully, readers of this column will systematically perform a checkup exam on your most valuable piece of office equipment in the pediatric office.

In the next column, I will discuss the major diagnostic criteria for AOM and results of a survey of pediatric otolaryngologists and pediatric infectious disease specialists as to the necessity of redness of the eardrum and bulging of the contour of the eardrum.

For more information:

• Richard Schwartz, MD, is from the department of pediatrics at Inova Fairfax Hospital for Children, Vienna, Va.