p i c u . it
New emergency in Paediatric Age: Severe Acute Respiratory Syndrome -
Giuseppe A. Marraro, MD
The appearance of Severe Acute Respiratory Syndrome SARS has focused attention on the possibility that new pathogens may develop, creating unexpected difficulty in identifying them and treating related pathologies. In such cases optimal international collaboration is indispensable, as has taken place with SARS, enabling the identification of the new pathogen in record time and opening up new perspectives for effective and specific treatment.
Up until March 21, 2003, the majority of patients affected by SARS have been adults aged 25-70 years. Few suspected cases of SARS have been reported among children aged less than 14 years. The incompleteness at present of reliable information does not allow us to make a precise estimate of morbidity and mortality in the different paediatric ages.
In the majority of cases SARS appears to have begun as a common airway infection which rapidly evolves into severe respiratory failure. In all children age groups the illness may present as severe asthmatic status. In the young child, in presence of high temperature, the first symptoms include seizures. In infants the respiratory failure evolves as in bronchiolitis.
The involvement of the small airways is very characteristic. Highly frequent in progressed stage SARS is similar to ARDS except for the presence of high temperature.
In all ages the respiratory phase can be characterised by early focal interstitial infiltrates progressing to more generalised, patchy, interstizial infiltrates. Interstitial lung pathology is evident in the full-blown stage, probably as progress of illness and as result of untreated progressive respiratory failure. Some patient in late stage have shown areas of lung consolidation like in lobar or multilobar pneumonia.
Other typical symptoms of viral infection can occur, including malaise, headache, confusion, loss of appetite, muscular pain and stiffness, rashes and diarrhea.
The severity of the illness can be highly variable, ranging from mild (the majority of patients are affected by this form) to severe form, which may be life threatening. At present it is not clear if death occurs before or during artificial ventilation, or for complication of associated pathology.
Spreading generally occurs by direct contact. It is not known why certain persons remain non-symptomatic despite substantial exposure.
The treatment of patients infected with new corona virus is similar to that recommended for other serious viral respiratory diseases. Supplementary oxygen, inhaled drugs to keep the airways clear of secretions and to prevent collapse of small airways, control of excessively high temperature and seizures, and intravenous fluids to support blood pressure and vital organs, are mainstays of supportive treatment. In some cases mechanical ventilation can be necessary to treat severe respiratory failure, to avoid hypoxia and to reduce hypercapnia. Mechanical ventilation must be considered to prevent sudden apnoea and cardiac failure.
There are no antibiotics that are effective against such viral respiratory disease. Its use is indicated in presence of over-infection due to known pathogens and for the treatment of community-acquired pneumonia with atypical cover. Empirical antibiotic therapy can create resistance and can select germs, which are insensitive to antibiotics, thereby complicating the evolution of the illness.
It seems that early use of high dosage of steroids (1-2 mg/kg/day and for severe cases, 4mg/kg/day) is very effective in adult patients even though steorids have not been effective in pulmonary viruses from different origins in children (bronchiolitis). Empirical use of corticosteroids must be made with caution in the acute phase because of severe immunodeficiency may result from their incorrect and prolonged use.
Ribavirin with or without use of steroids has been used but its effectiveness has not been demonstrated.
The current recommendation is that children with SARS should be kept in respiratory isolation wards and more severe cases treated in isolated sub intensive care units.
Oxygen therapy can be useful in presence of interstitial pathology and reduced alveolar gas diffusion. Its use must be strictly monitored in order to avoid toxic side effects and in particular free radical formation, damage to type II pneumocytes, which produce surfactant, and inhibition of produced surfactant. Side effects can be mitigated using correctly warmed and humidified oxygen (35-37 °C and 100%-saturated vapour). The use of oxygen in hypercapnic infants can lead to respiratory arrest. Hypercapnia must be recognised and treated adequately with artificial ventilation.
Cold and dry oxygen must be avoided in any case due to consolidation and difficult elimination of secretions. In addition, its use can favour obstruction of small bronchioles, which can aggravate air trapping and respiratory fatigue.
The use of inhaled drugs to keep airways clear must be evaluated carefully in relation to cough efficacy. If cough is weak and child appears exhausted, their use must be avoided. Aerosol therapy (saline solution and sodium bicarbonate) with humidified and warmed gases is an excellent method to soften secretions and aid their elimination.
Aminophylline can used to reduce bronchiolar spasms and to improve respiratory muscle strength. During its use, cardiac rate must be strictly monitored to avoid appearance of life-threatening tachicardia.
Particular attention must be paid to preventing closure and collapse of small airways, especially in infants and young children having reduced diameter of airways, which therefore are easily obstructed and high closure volume, which favours the rapid appearance of hypercapnia and hypoxia.
The following treatments can be applied in children with severe air trapping but with effective spontaneous breathing:
In case of need for artificial ventilation:
Non-invasive ventilation has been used with good results in adults.
The pathology is an infection of great medical impact and which has created widespread alarm. It is essential to appreciate that SARS is a severe respiratory illness caused by a new virus, a very recently classified member of the corona virus family. However it is not a disease that is in any way related to being Asian or to the fact that Asia happened to be the place where cases were first identified.
Therefore we wish to ask for the support and help of the general
population towards affected areas of the world, requesting recognition of how difficult
this situation is for the patients affected and their families. There is an urgent need to
pull together in a time when all communities need support and empathy, not unfounded
stigma or bias or shunning due to racial origin.
SARS Information Resources
Only for medical professional: up to date information in Intensive Care and Anaesthesia.
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