Clinical Guideline on Management of Viral Croup
This Guideline had been developed by Quality Assurance Sub-committee, COC in Paediatrics and the expert authors for the Hospital Authority according to the state of medical knowledge at the time of publication. It has been established that doctors can act in accordance with a practice accepted as proper by a responsible body of medical opinion even though others may adopt a different practice. As such, this guideline is for general guidance only; the management of individual cases must be the clinical judgment and decision of the medical practitioners after considering all relevant circumstances, information and up-to-date medical knowledge. In view of the general nature of this guideline and the changes in medical science, the Hospital Authority, the Paediatric COC and the authors do not assume or accept any liability for this guideline.
Explanatory Notes on Level of Evidence and Grading System on Recommendation
The definition of types of evidence and grading recommendations originate from the US Agency for Health Care Policy and Research (AHCPR) and are also recommended and used by the Royal College of Paediatrics and Child Health.
Evidence is graded upon the methodological qualities. Guidelines normally contain many different recommendation based upon different levels of evidence. It is important that users are aware of the level of evidence on which each guideline recommendation is based. The link between guideline recommendation and the supporting evidence should be made explicit. Separating the strength of the recommendation from the level of evidence helps in situations where extrapolation is required to take the evidence of a methodologically strong study and apply it to the target population. Grading of recommendation in addition to level of evidence allow more flexibility for future revision. However, it is important to emphasis that the grading does not relate to the importance of the recommendation. Currently, there are discussions on taking account of relevant high quality non-RCTs and qualitative research and to incorporate them into appropriate grading system.
Clinical Guideline on Management of Viral Croup
Croup is an acute clinical syndrome typified by an acute onset of harsh barking cough, hoarseness, inspiratory stridor and respiratory distress.
Differential diagnoses include foreign body aspiration, bacterial tracheitis, acute epiglottitis and acute laryngotrachebronchitis or viral croup.
Viral croup usually starts with rhinorrhoea, sore throat, and mild fever for few days. The child then develops the characteristic barking cough, hoarseness, and inspiratory stridor, with or without the persistence of the low-grade fever. Symptoms tend to be worse at night but child is usually not acutely ill. Drooling is not common in viral croup. Parainfluence types 1, 2 & 3 are the most important infectious agents but others like influenza virus type A & B, respiratory syncytial virus, adenovirus, rhinovirus and enteroviruses are also common. In rare cases, herpes viruses and bacteria like Haemophilus influenza type B and Staphylococcus aureus had been isolated.
The incidence of viral croup peaks in the winter months. 91% of cases occur in less than 5 years of age with most cases occur before 2 years.1 There is a slight male preponderance. In 1999, 0.81% of all children discharged from Hospital Authority hospitals in Hong Kong had the diagnosis of acute viral croup.2
Epiglottitis is a serious illness and is the most important differential diagnosis to exclude. However, it is less prevalent in Hong Kong. Most cases are preceded by upper respiratory tract symptoms but the onset of acute epiglottitis tends to be more abrupt and the child becomes ill quickly. There is associated high fever, irritability, restlessness and saliva drooling is prominent.
Bacterial tracheitis can be a complication of viral croup. The child usually develops high fever and looks toxic. However, its onset is usually not as abrupt as acute epiglottitis and there is a more typical barking cough. Drooling is not a feature in most cases.
Foreign body aspiration can usually be diagnosed from clinical history.
Croup can be diagnosed clinically in most cases. Throat examination is usually not necessary and must not be done in cases of suspected epiglottitis unless a skilled operator in intubation and emergency tracheostomy is available.
The objectives of this review are to evaluate the available evidences regarding:
i) The role of laboratory tests in viral croup
ii) The monitoring of children with diagnosis of viral croup
iii) The treatment options in viral croup
Methods for literature search are from 1) the MEDLINE and EMBASE databases from 1983 to 2000 using keywords - laryngotracheobronchitis, croup and 2) Cochrane Library databases for any meta-analyses and randomised control trials (RCT) in treatment of viral croup
The grading of evidence and recommendations are based on the definitions from the report ?Standards for Development of Clinical Guidelines in Paediatrics and Child Health published by the Royal College of Paediatricians and Child Health 1998 and adopted by the Working Group on Clinical Guideline and Evidence Based Medicine.
I. The Role of Diagnostic Laboratory Test in Viral Croup
Any painful laboratory test should be avoided or kept to a minimum and reserved for those uncertain cases.
1) Complete Blood Picture
Complete blood picture will show mild leucocytosis and lymphocytosis but this is a very non-specific finding.
Evidence: It does not help the diagnosis and will not alter the management.
Recommendation: Blood taking for complete blood picture is a painful procedure and should be avoided.
2) Arterial Blood Gas
Arterial blood gases correlates well with the clinical severity and progression. Hypoxaemia is an earlier indicator of respiratory compromise and hypercapnia is a sensitive indicator of the severity of pulmonary disease. However this procedure is painful and the validity of the results obtained from an uncooperative and screaming child is questionable.
Evidence: The procedure is painful and the validity of the results from an agitating child is questionable.
Recommendation: Recommended only in very severe or intubated cases.
3) Lateral Neck Radiograph
Lateral neck X-ray film will show overdistension of hypopharynx and proximal larynx and the posteroanterior film will show the "steeple sign" due to the subglottic swelling. However most cases can be diagnosed on clinical ground and taking an X-ray may make the child more agitated.3
Evidence: Limited utility of lateral neck radiograph in diagnosing croup and have variable conclusions regarding their utility in diagnosing epiglottitis. The stress of the procedure may worsen the clinical course especially in acute epiglottitis.
Recommendation: Radiograph is not necessary in obvious case. Radiograph may be considered in stable patients with suspected foreign body or anatomical abnormalities.
II. Monitoring of Children with Diagnosis of Viral Croup
1) Pulse Oximetry
No RCT has been done to evaluate the clinical usefulness of pulse oximetry. However being a non-invasive monitoring method, it is useful in moderate to severe cases. 4,5
Evidence: Most symptomatic children with croup will have normal findings on pulse oximetry and low oxygen saturation is uncommon except in severe cases.
Recommendation: Hypoxaemia is an indication of respiratory compromise, monitoring of oxygen saturation is useful in moderate to severe cases.
2) Respiratory Rate
Tachypnoea correlates well with the severity of the disease but there is no study to look at the usefulness of this parameter in viral croup.
3) Heart Rate
Tachycardia reflects hypoxaemia and acidosis.
4) Conscious Level
This correlates well with the severity of the disease.
Recommendation: Respiratory rate, heart rate and conscious state are useful clinical parameters for monitoring of children with viral croup.
5) Pulsus Paradoxus
A prospective blinded comparison study had found that this correlated well with the severity and improvement in croup.6 However the device used in the study, a non-invasive continuous blood pressure and respiration monitoring device is not normally available for routine clinical use in Hong Kong.
Recommendation: Pulsus paradoxus is a useful clinical parameter but is not recommended unless a non-invasive device is routinely available.
6) Transcutaneous Carbon Dioxide Pressure Monitoring
Hypercapnia is a late event in upper airway obstruction. A prospective study involving 17 children with severe croup had found that this correlated well with the severity of croup.5
Recommendation: Transcutaneous carbon dioxide pressure monitoring provide useful clinical parameter in severe cases.
7) Scoring System
A few scoring systems have been validated in clinical trials, e.g. Westley scoring system (Appendix II). There is, however, no clinical study to evaluate its usefulness in clinical practice.
Recommendation: Scoring system for clinical severity is not necessary in routine clinical practice.7
III. Management of Viral Croup
Mild cases can be managed in A&E department or out patient clinic providing signs of deterioration can be watched out for ?increasing stridor, increasing respiratory distress and increasing fatigue.
Recommendation: A calm and warm environment, minimal disturbance together with parenteral comfort is all that needed in most cases of the mild croup.
1) In Children with Moderate to Severe Croup, is Steroid Therapy Effective in Reducing Acute Symptom?
- Corticosteroids is effective in reducing acute symptoms in moderate to severe cases.
- Oral administration is as effective as parenteral.
- Corticosteroids is recommended for treatment of moderate to severe viral croup.
- A single dose of 0.6 mg/kg dexamethasone is recommended until more studies comparing a smaller dose are done.
- Oral administration is as effective as parenteral and is preferred because of its safety and efficacy.
2) Is Nebulizer Steroid Therapy as Efficient as Systemic Steroid in Reducing Acute Symptoms?
Evidence: Nebulized budesonide at a single dose of 2 mg for all ages is a reasonable alternative to oral or parenteral dexamethasone for management of moderate to severe croup.
Recommendation: In children with vomiting, nebulized budesonide or intramuscular dexamethasone may be preferred.
3) Nebulized Adrenaline
0.05 ml/kg of 2.25% racemic adrenaline mixed with 2.5 ml normal saline
(Minimum dose 0.25 ml to maximum dose 0.75 ml)
0.5 ml/kg/dose 1:1,000 L-adrenaline added to 3 ml 0.9% NaCl solution
(Maximum dose: <4 years old - 2.5 ml, >=4 years old - 5 ml)
Evidence: Nebulized adrenaline can provide temporary symptomatic relief before corticosteroids takes effect.
Recommendation: - Nebulized adrenaline can be given as an initial treatment. However, it should not be used as the only treatment due to the possibility of relapse. Patient should not be discharged just based on the initial improvement.
- It should be avoided in children with pre-existing cardiac disorder.
IV. Other Supportive Management
No RCT has been done to evaluate the use of oxygen but a child with moderate to severe upper airway obstruction may have a lower than expected oxygen saturation.24
Recommendation: Routine oxygen supplement is not necessary but it should be given if the child has progressive tachypnoea, tachycardia, cyanosis and laboured breathing.
There is no study to evaluate the importance of hydration. However with the exaggerated negative intra-thoracic pressure due to the laryngeal obstruction, child is prone to develop pulmonary oedema.
Recommendation: Maintain hydration by encouraging oral fluid intake and intravenous fluid supplement in very distress child. Over-hydration should be avoided.
3) Endotracheal Intubation
Recommendation: Intubation is rarely needed but act if necessary.
4) Chest Physiotherapy
No study has been done to evaluate this treatment but looking at the underlying pathology, it is unlikely to be useful as most of the obstruction is at the subglottic area. Physiotherapy may also aggravate the already distressed child.
Recommendation: Routine chest physiotherapy is not recommended.
5) Humidified Air
Recommendation: The use of humidified air is not recommended.
No RCT has been done but as virus is the most common etiologic agent in most cases, there is no place for antibiotic unless there is a strong reason to suspect a bacterial cause or if there is a secondary bacterial infection.
Recommendation: Antibiotic is not recommended unless bacterial infection is clinically likely to be present.27
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