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Introduction   

Kawasaki Disease is an acute febrile syndrome that occurs primarily in children and has an unknown cause. In addition to acute fever, rash, and mouth and throat irritation, Kawasaki disease causes acute and chronic cardiovascular inflammation and is the leading cause of acquired cardiovascular disease.  

It most commonly occurs in children under the age of 5 years, and the current rate of incidence ranges from 9 to 20 children per 100,000 each year (3). Thousands of children are hospitalized for management of Kawasaki Disease each year and the most serious risk is inflammation of the coronary arteries, which occurs in 15%-25% of clients (5).  

Nurses who care for the pediatric population in any capacity must be familiar with Kawasaki Disease, the signs and symptoms, and long-term sequelae to provide the most effective care and improve health outcomes for affected children.

Epidemiology

History and Incidence

Kawasaki Disease (KD) was first documented in Japan in the 1960’s by Dr. Tomisaku Kawasaki who noted the acute symptoms of rash and fever and suspected a link to subsequent cardiovascular symptoms. By 1974, autopsies of 10 children with sudden cardiac arrest after KD had confirmed this connection and Dr. Kawasaki published a report of 50 clients to be used as a guide for clinicians worldwide (2).

Because of Dr. Kawasaki’s work and documentation, KD became collectively recognized around the world and what would previously have been unknown or misunderstood causes of death began being identified as KD. Cases began being identified in Hawaii in the early 1970s and a case was retroactively diagnosed in Los Angeles, California in 1971 based on an autopsy report (2).

Now KD is recognized as occurring worldwide, though the highest incidence remains in Japan. In the United States, KD affects anywhere from 9 to 20 per 100,000 children each year and is overall considered rare. Once a person has had KD, the rate of recurrence is less than 1% and clients typically only experience it once.

Risk Factors

The vast majority of children affected are under the age of 5 years. The disease rarely occurs in people over the age of 18. Boys are also slightly more likely to be affected than girls and children with Asian or Pacific Islander races are also at a higher risk (3).

Children from lower socioeconomic backgrounds are more likely to have a delay (on average, 1-2 days) in seeking care which increases their risks of complications and poor outcomes from the disease (4).

Healthcare Costs

Children diagnosed with KD utilize healthcare services more than their peers, both during the acute illness and in the year following diagnosis. The CDC cites 5,440 hospitalizations from KD occurring in 2016, with 3,935 of these being children under age 5 (3). Within 1 year of discharge, 45.5% of children had at least 1 emergency department visit and 15.6% of children were re-hospitalized with KD-related complications. The median individual cost of a KD-related hospitalization is $6,000, though costs can reach up to $30,000 for just one hospitalization. Nationwide, the total annual costs for KD-related care, including hospitalization and follow-up, range from $38 million to $110 million (8).

Pathophysiology

Despite many years of study, the cause of KD is still unknown. It is not contagious, so it cannot be spread from person to person. The current suspicion is that it may be sparked by an abnormal post-infection immunologic response where the body begins attacking the walls of blood vessels after a viral or bacterial infection. There may also be a genetic predisposition to this occurring, as clients of Asian descent seem to be disproportionately affected (1,2,7).

Regardless of what initially triggers the syndrome, the course of KD is divided into 3 clearly defined clinical stages; acute, subacute, and convalescent.

Acute Phase:

The acute phase of KD begins with a persistent high fever, usually lasting 5 days or more and not very responsive to antipyretics like acetaminophen or ibuprofen. Children are highly irritable and difficult to console. The first day of fever is considered Day 1 of illness when mapping out the disease.

Systemic vascular inflammation follows, which leads to many of the other characteristic signs and symptoms. Small blood vessels of the eyes are affected, and children may have conjunctival injections or uveitis which can cause eye pain, floaters, or blurred vision (1,2,7).

The mouth is also highly affected, with swelling and redness of the tongue, lips, and throat. Excessive swelling and erythema of the tongue can lead the papillae (taste buds) to be more prominent and stand out with a paler, whitish color against the rest of the tongue, giving it a classic “strawberry tongue” appearance. Burst blood vessels or the oral mucosa cause microscopic cell death of these tissues and lead to cracked and peeling skin of the lips (1,2,7).

Many children also have significant cervical lymphadenopathy. Lymph nodes may be >15mm in diameter, firm, and non-fluctuant, though usually not very painful.

Similar to what happens to the oral mucosa, the microvasculature of the extremities is affected and there may be significant redness and swelling of the hands and feet. A diffuse, nonspecific rash often forms on the trunk and may spread outward. It is most often maculopapular, not itchy, and usually appears during the first few days of fever.

Other potential symptoms of systemic inflammation include joint pain, diarrhea, and involvement of many organs such as hepatic dysfunction, pericarditis, myocarditis, pericardial effusion, pneumonitis, lymphadenitis, and valvulitis. Much of this inflammation will resolve on its own as the disease does, but the effects on the heart will not and are among the most dangerous complications of the disease (1,2,7).

Subacute Phase:

About 1-2 weeks after the acute symptoms begin, the fever, rash, and irritability resolve. However, symptoms such as irritability, anorexia, and conjunctival injection remain for an additional 1-2 weeks, a time known as the subacute phase. Desquamation, or peeling, of the palms and soles, may occur and even last for months or years. Abnormal clotting begins to occur, and persistent inflammation and emergence of aneurysms affect the coronary arteries. This combination makes the subacute phase the most dangerous time with a high risk of sudden death (1,2,7).

Convalescent Phase:

The convalescent phase begins when the clinical symptoms are gone but the body is still recovering from widespread inflammation. This phase usually lasts around 6-8 weeks after the initial presentation and is considered resolved when the sedimentation rate returns to normal (1,2,7).

Phases of Kawasaki Disease Quick Guide

(1,2,7)

Prognosis

The prognosis depends largely on the prompt onset of effective treatment. With appropriate treatment, coronary artery aneurysm risk is reduced to <5%, and mortality from KD is only 0.17% in the United States.

When deaths do occur, they are almost always due to cardiac complications and often occur suddenly, most often within the first 1-2 months of onset, though deaths from resulting coronary artery disease can occur as long as 10 years later. When coronary artery disease is absent, the client’s prognosis is excellent. (7)

Diagnosis

Diagnosing KD can be difficult as the symptoms develop over time and may not immediately be identifiable as KD. Diagnosis is based on clinical presentation as well as the exclusion of other possible diagnoses.

The clinical criteria include fever >5 days (the hallmark symptom) and 4 of the following: 1) conjunctival injection, 2) oral mucosa changes, including erythema, edema, cracking, strawberry tongue, 3) peripheral extremity edema, erythema, or desquamation, 4) polymorphous truncal exanthem, 5) cervical lymphadenopathy with at least 1 node >1.5mm.

KD presentation may be similar to other diagnoses like scarlet fever, measles, medication reactions, Rocky Mountain spotted fever, juvenile idiopathic arthritis, and post-covid multisystem inflammatory syndrome. Laboratory testing such as complete blood count (CBC), antinuclear antibody (ANA), rheumatoid factor, erythrocyte sedimentation rate (ESR), throat and blood cultures, and COVID-19 testing can help differentiate between KD and other potential diagnoses (7).

Common laboratory findings in the case of KD include leukocytosis with a left shift, mild anemia, thrombocytosis (platelet count of 450,000/mcL), elevated liver enzymes, reduced serum albumin, proteinuria, and elevated ESR and C-reactive protein, both of which indicate systemic inflammation. If a lumbar puncture is performed, increased WBC in the cerebrospinal fluid may be present. The age of the child should also be considered, as KD would be more likely in children under 5 (7).

For children with fever >5 days and only 2-3 of the clinical criteria, atypical KD should be considered as coronary artery aneurysm may still occur in atypical disease. Cardiology consultations and diagnostics like ECG and echo are still pertinent for these clients.

For clients who meet the criteria or KD is suspected, a pediatric cardiologist should be consulted. An ECG and echocardiogram must be done initially and again throughout recovery. Cardiac changes may occur over time, so repeat cardiac testing should be done at 2-3 weeks, 6-8 weeks, and even as long after onset at 6-12 months. Common abnormalities on ECG include arrhythmias and left hypertrophy. Echo results may show coronary artery aneurysms, pericarditis, myocarditis, or valvular regurgitation. Clients with aneurysms may require additional testing like arteriography. (7)

Treatment

Treatment of KD centers on reducing inflammation, blood clotting risk, and damage to the coronary arteries and heart. The gold standards of care are intravenous immune globulin (IVIg) and high-dose aspirin.

IVIg is used to treat a variety of autoimmune and inflammatory disorders and works by downregulating inflammation through its interaction with the immune and vascular systems. Typical treatment is 2 g/kg given intravenously over 10-12 hours. A second dose of IVIg may be indicated if a child’s fever and other symptoms have not improved within 36 hours of the first dose (6,7).

High-dose aspirin can reduce fever and inflammation and also has blood-thinning properties to prevent the formation of blood clots. A dose of 20-25 mg/kg is given orally 4 times a day for the first few days of aggressive treatment. This is reduced to 3-5 mg/kg once per day around day 14 of illness or once the fever has resolved for around 5 days, depending on the preference of the treating provider. The lower dose of aspirin is maintained for at least 8 weeks when inflammatory markers have returned to normal and coronary artery aneurysm is absent on echocardiogram (6,7).

IVIg and aspirin treatment should be initiated as soon as possible for the best chance of preventing cardiovascular complications. The longer a child has had a fever, the more likely their risk of coronary artery damage and reduced response to treatment. The efficacy of this treatment regimen after 10 days of symptom onset has not been well studied. (6,7)

Nursing Implications

Depending on your setting, the stage where you encounter clients with KD and nursing interventions will vary.

In settings where children are seen for acute concerns, such as pediatric offices, urgent care, emergency departments, and even inpatient pediatric units, children may be in the first few days of symptoms and KD may not have been identified yet. Gathering a complete and accurate history in these settings is integral to an accurate and timely diagnosis of KD.

Clients should be questioned about the onset of fever, other present symptoms, recent viral or bacterial illnesses, and sick contacts. Fever lasting longer than 5 days should always be a red flag that alerts you to the possibility of KD.

For children being seen before the 5-day mark of fever, KD may be more difficult to identify, especially if other hallmark symptoms have not fully emerged. This is why education for seemingly typical viral illnesses should always include a return for reevaluation if the fever persists beyond 5 days.

Anticipating and assisting with diagnostic testing such as serum blood draws, respiratory panel swabs, throat cultures, ECG, or echocardiogram is a common part of nursing care when KD is suspected.

For nurses encountering clients who have an existing diagnosis of KD, typically in the inpatient pediatric setting, knowledge of the various stages of disease, typical treatment, expected response to treatment, and signs and symptoms of complications are necessary for safe and effective care. Nurses caring for KD clients should remember that the risk of thrombosis and coronary artery aneurysms is highest during the 2nd-4th week of illness, during the subacute phase, or for clients who had a delayed onset of treatment.

Educating parents about the use and mechanism of action of high-dose aspirin and IVIg is a common nursing intervention. Nurses should watch closely for improvement of symptoms, particularly fever, and should notify the provider if symptoms persist or seem to be worsening within 36 hours of treatment initiation.

Finally, even clients who are in the convalescent period will need continued monitoring and nurses may encounter these clients in the outpatient pediatric setting. Close monitoring and ensuring clients attend their follow-up testing, such as repeat echocardiograms, is paramount since 50% of KD-related deaths occur more than 1 month after initial disease onset.

It is also important to note that IVIg administration may inhibit an appropriate immune response to attenuated viral vaccines such as MMR and varicella. For children who received IVIg for treatment of KD, these vaccines should be delayed for 11-12 months after treatment to ensure effective immunity (7).

Reye’s syndrome is a rare complication of viral illness that occurs more commonly in children who have been taking aspirin. Because of the relationship between this complication and aspirin, viral illnesses like influenza should be avoided as best as possible for children who received high-dose aspirin for treatment of KD. This includes the annual administration of influenza vaccines, which nurses are in a key position to promote (7).

Clients should also be advised to speak with their dentist about their history of KD to determine if prophylactic antibiotics are needed before dental procedures. Dental procedures that may impair the integrity of the highly vascular gums and allow bacteria to enter the bloodstream are of particular risk to clients with KD as persistent damage to heart valves puts them at increased risk of developing endocarditis (9).

Case Study

Harrison is a 24-month-old male brought to the pediatrician’s office with a fever for 3 days. His mother reports that he has been fussy and not eating as much and he reports his mouth hurts. Upon exam, he has rhinorrhea, mild conjunctival injection, and moderate pharyngeal erythema. His ears have some mild erythema to bilateral TMs, but landmarks are intact and there is no fluid or bulging. His lungs are clear, and his respiratory effort is normal. His vital signs are normal except for a temporal temperature of 101.2F.

He is a little fussy but overall cooperative during his exam and eats a popsicle in the office after being given a dose of Tylenol. His mother notes he had a cold last month and some children at his daycare have had strep throat in the last week. A rapid strep test is done and is negative, a second swab is sent for a culture.

He was diagnosed with a viral URI and sent home with instructions to call back for any worsening or persistent symptoms or signs of dehydration.

Two days later, his mother calls and speaks to the nurse and states that Harrison still has a fever today, which is day 5. She reports he is still irritable, and his eye redness has worsened as well as he now has dry and cracked lips which are painful and making it difficult for him to eat anything. She is concerned he has now developed a rash on his abdomen and down into his diaper region. The nurse advises Harrison’s mother to take him to the ED.

Once in the ED, he is tested for COVID-19 which is negative, his throat culture is back and also negative, and a serum blood draw is done, revealing mild leukocytosis, a platelet count of 465,000, and an elevated ESR. Pediatric cardiology is consulted, and an echocardiogram is done, revealing aortic valve regurgitation.

Harrison was diagnosed with Kawasaki Disease and admitted to the pediatric unit where he received aggressive administration of IVIg and high-dose aspirin. Within 24 hours, his fever had resolved, and his other symptoms began to improve. A repeat echocardiogram 1 week later shows improved valve regurgitation and that coronary arteries are still healthy.

He is discharged home with close follow-up with his pediatrician and cardiologist over the coming weeks and months.

Conclusion

Kawasaki Disease is a rare but potentially life-threatening disorder that requires prompt identification and treatment to reduce complications and mortality. A clear understanding of the disease process, its diagnosis, and treatment is necessary for effective nursing care. Even once the illness has resolved, the implications and risks may last a lifetime for affected clients and nurses are in a key position to provide education and monitoring as needed.

By completing this course, the learner has hopefully improved their knowledge on this topic and is better prepared to serve their client population.

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