Diagnosis and pharmacological management of acute otitis media

Pediatric Nursing, Sept-Oct, 1998 by Nancy H. Montville, Mary A. White

Acute otitis media (AOM) is an inflammation of the middle ear, accompanied by a rapid onset of signs and symptoms. These include pain, fever, irritability, anorexia, or vomiting (Berman, 1995). AOM occurs when there is effusion of fluid into the middle ear. Additionally, bacteria from the nasopharynx are drawn into the cavity, leading to the suppuration found in AOM.

AOM accounts for more than 30 million pediatric office visits per year. The condition occurs most frequently in the 6-month to 6-year population, with the greatest number (83%) occurring in children less than 3 years of age (Burns, Barbar, Brody, & Dunn 1996). There is a greater rate of occurrence in boys than girls. There are also racial differences in the incidence and prevalence of the disease. White children are more frequently affected than blacks, and the craniofacial structure of Native Americans and Eskimos is thought to be a contributing factor to their increased risk.

Other predisposing factors include exposure to secondary smoke, formula feeding, lower socioeconomic status, day care center attendance, and a sibling or parent history of severe recurrent otitis media (Hoekelman, Friedman, Nelson, & Siedel, 1992). Age at first episode is relevant to the prediction of future infections. The younger children are when they experience their first episode of AOM, the more likely they are to have future episodes (Klein, 1994).

Pathophysiology

The eustachian tube serves three major functions: ventilation, drainage, and protection. When a child is at rest, the nasopharyngeal end of the eustachian tube is closed. It is opened by the motions associated with swallowing, yawning, talking, and crying. When ventilation is normal, the pressure in the middle ear is comparable to atmospheric pressure. Normal pressure permits optimal mobility of the tympanic membrane and unobstructed conduction of sound (Hoekelman et al., 1992; Parsons & Waid, 1996).

The eustachian tube also serves as a drainage path for secretions. Secretions produced by goblet cells and mucus producing cells flow from the middle ear and eustachian tube to the nasopharynx (Parsons & Wald, 1996).

The eustachian tubes' structure serves a protective function. Its length provides distance between the bacteria-filled nasopharynx and the sterile middle ear cavity. The shorter, more horizontal and more flaccid eustachian tubes decrease the effectiveness of this protective defense. Children have been shown to have poorer ventilatory function of their eustachian tubes than adults. All of these factors predispose children to an increased risk of AOM (Maxson & Yamauchi, 1996).

When ventilation is impeded as a result of eustachian tube obstruction, negative pressure develops in the middle ear. Furthermore, this negative pressure generates continuous suction on the dysfunctional eustachian tube. This suction causes secretions to flow from the nasopharynx to the middle ear. Secretions replete with bacteria set up a perfect medium for bacterial proliferation, and hence acute otitis media (Maxson & Yamauchi, 1996; Parsons & Wald, 1996).

Clinical Findings

The child's history may vary in the type and intensity of symptoms. Ear pain, exhibited by irritability, or the inability to sleep, feeding difficulty, fever, diarrhea, vomiting, lethargy, or sudden hearing loss may be reported (Shapiro & Bluestone, 1995). Many parents report ear pulling, but this alone is not a reliable indicator of AOM.

AOM is closely linked with viral infections, especially respiratory syncytial virus, adenovirus, and influenza virus. Frequently, the young child who has suffered a recent upper respiratory tract infection lasting several days, presents to the primary care provider with symptoms of fever, irritability, and poor appetite. Otoscopic findings can confirm a diagnosis of AOM, even in the absence of symptoms.

Accurate diagnosis of AOM can only be made after confirmation of positive physical findings with pneumatic otoscopy. Pneumatic otoscopy permits the examiner to evaluate the appearance and mobility of the tympanic membrane (TM). The normal TM is translucent, and the short process and handle of the malleus are visible through the TM. The cone of light is visible, and the drum moves laterally and medially with the application of negative and positive pressure during pneumatic otoscopy.

Positive physical findings of full or bulging TM, absent or obscured bony landmarks, distorted or absent light reflex, decreased or absent mobility of TM, and bullae between layers of the TM are indicative of AOM. Erythema, or the presence of a fluid level, are not diagnostic of AOM in the absence of other findings (Berman, 1995). A tympanocentesis for culture and sensitivity of middle ear effusion is performed in rare cases. These include toxic patients, patients with complications such as mastoiditis, immune system compromise, or recurrent infections, and newborns (Berman, 1995; Graham & Uphold, 1994).

Causative Organisms and Antibiotic-Resistance

Knowledge of causative organisms is essential when selecting an antibiotic for treatment of AOM. The organisms most commonly identified in patients with AOM are Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis (Shapiro & Bluestone, 1995; Eden et al., 1996).