ondansetron in combination with oral rehydration for

patients with dehydration due to nausea and vomiting.

Ondansetron can be given as an oral dissolving tablet or

intravenously (IV; 2 mg, 4 mg). Antidiarrheal agents are not

recommended. Rapid oral rehydration has been shown to

be as effective as IV fluid therapy in restoring intravascular

Signs or symptoms of

dehydration

Fluid resuscitation

Stabil ization of vital signs

Eva luate for signs of shock

Obtain history of all intake and output

Assess severity of dehydration

Identify underlying disease or ill ness

OraljiV rehydration

ppropriate lab or radiographic studies

Correct electrolyte abnormal ities

Etiology undetermined

Admit for continued testing and

therapy

Etiology determined

Admit for further therapy OR discharge if

no clin ical signs of dehydration and no

significant ongoing losses

.6. Figure 51-1 . Dehydration diag nostic algorithm.

CHAPTER 51

Table 51-2. Calculations for maintenance fluid

in the pediatric patient.

Patient Weight

First 10 kg

Second 10 kg

Each additional 10 kg

4/2/1 Method Holiday-Segar Method

4 ml/kg/hr 1 00 mljkg/day

2 ml/kg/hr

1 ml/kg/hr

50 ml/kgfday

20 ml/kg/day

volume and correcting acidosis in patients with moderate

dehydration. For every 25 children treated with oral rehydration treatment for dehydration, 1 fails and requires

N therapy. Oral rehydration solutions for infants and toddlers should contain 45-50 mEq/L of sodium and 25-30 giL

glucose (Pedialyte, Infalyte). Give 5-10 mL of fluid every

5-10 minutes and increase as tolerated, with the goal of

30-50 mL/kg over a 4-hour period. If voruiting occurs, wait

30 minutes after last episode before reinitiating oral fluids.

An estimate for fluid replacement is 10 mL/kg body weight

for each watery stool and 2 mL!kg body weight for each

episode of vomiting.

Dehydration can be categorized according to osmolarity

and severity. Serum sodium is a good marker of osmolarity

(assuruing a normal glucose) and guides replenishment

therapy. Isotonic dehydration is the most common (80%).

Sodium and water losses are similar in intra- and extracellular compartments. Maintenance fluid requirements

plus half the fluid deficit are administered over the first

8 hours, and the remaining fluid deficit over the following

16 hours. Hypotonic dehydration (Na < 1 30 mEq/L) occurs

when more sodium than water is lost. Calculate sodium

deficit for replacement fluids. Sodium deficit (mEq) =

(135-measured Na) X (pre-illness weight in kg) x 0.6.

Sodium deficit should be replaced over a 4 -hour period

but should not exceed 1 .5-2.0 mEq/hr; 0.9 NS is an appro ­

priate solution. Hypertonic dehydration (Na >150 mEq/L)

exists when more water is lost than sodium. The free water

deficit is calculated as free water deficit (mL) = (measured

serum Na-145) x 4 mL!kg x pre-illness weight (kg).

Because of the risk of cerebral edema, correct the free water

deficit over a 48-hour period, with a goal of reducing

serum sodium by no more than 1 0-15 mEq/L!day; D5 \4

to D5 liz NS are appropriate solutions.

DISPOSITION

� Admission

Most patients with moderate-to-severe dehydration with

significant acidosis should be admitted to the hospital

(serum bicarbonate level of �13 is predictive of return to

the ED for treatment failure as outpatient). Other

indications for adruission include significant ongoing fluid

losses, inability to tolerate oral fluids, hypotonic or hypertonic dehydration, or undetermined etiology in need of

further assessment. Patients with signs of increased intracranial pressure or DKA should be adruitted to an intensive

care unit.

� Discharge

Patients with no clinical evidence of dehydration or those

with mild-to-moderate isotonic dehydration who have

received adequate fluid rehydration (oral or N) can be

discharged home.

SUGGESTED READING

Colletti JE, Brown KM, Sharieff GQ, Barata lA, Ishimine P. The

management of children with gastroenteritis and dehydration

in the emergency department. 1 Emerg Med. 2010;38:681'Hi98.

Freedman SB, Adler M Seshadri R, Powell EC. Oral ondansetron

for gastroenteritis in a pediatric e mergency department. N Eng/

1 Med. 2006;354:1698-1705.

Freedman SB and Thull-Freedman JD. Vomiting, diarrhea and

dehydration in children. In: Tintinalli JE, Stapczynski JS, Ma

OJ, Clince DM, Cydul.ka RK, Meckler GD. Tintinalli's

Emergency Medicine: A Comprehensive Study Guide. 7th ed.

New York, NY: McGraw-Hill, 20 1 1, 830-839.

Otitis Media

Suzanne M. Schmidt, MD

Key Points

• Disti nguish between acute otitis media (AOM) and otitis

media with effusion (OME), both of which present with

a middle ear effusion.

• Clinical findings most suggestive of AOM are a bulging

tympanic membrane (TM) with a purulent effusion,

whereas the TM in OME has a clear effusion with a

normal or retracted position.

INTRODUCTION

Otitis media refers to the presence of inflammation or

infection in the middle ear space. A middle ear effusion

without infection is called otitis media with effusion

( OME) or serous otitis. Infection of fluid in the middle ear

is called acute otitis media (AOM). Diagnosis of AOM

should be based on the acute onset of signs or symptoms

of middle ear inflammation (fever, ear pain, distinct

erythema of the tympanic membrane) in conjunction with

a middle ear effusion seen on physical exam.

Ear disease is common in children, with 90% of

children having at least 1 episode of a middle ear effusion

and two thirds with at least 1 episode of AOM by school

age. The peak incidence of AOM occurs between 6 and

24 months of age.

Episodes of AOM are often preceded by a viral upper

respiratory tract infection (URI). The eustachian tube in

children is shorter and more horizontal than in adults.

Eustachian tube dysfunction associated with a URI can

lead to a middle ear effusion (OME). Bacterial pathogens

in the nasopharynx ascend via the eustachian tube, leading

to infection of the fluid in the middle ear (AOM).

AOM is caused by bacteria in 50--80% of cases, most commonly Streptococcus pneumoniae or nontypable Haemophilus

221

• Erythema alone is a poor predictor of AOM and must

be combined with other TM characteristics to make a

diagnosis.

• Antibiotic treatment may be ind icated for some

episodes of AOM, but is not indicated for OME.

• Assess the patient for possible compl ications of AOM.

infl.uenzae and less commonly Moraxella catarrhalis. Purulent

otorrhea may be caused by Staphylococcus aureus or

Pseudomonas aeruginosa as well. Common complications of

AOM are persistent middle ear effusion, tympanic membrane

perforation, and tympanosclerosis. Other complications of

AOM include cholesteatoma, hearing loss, tinnitus, balance

problems, and facial nerve injury. Intracranial complications

are rare and include mastoiditis, intracranial abscess, meningitis, and venous sinus thrombosis.

CLINICAL PRESENTATION

..... History

Children with AOM usually present with acute onset of

signs and symptoms of inflammation from AOM, such as

fever and ear pain. This is often preceded by URI symp ­

toms.