Indian J Pediatr DOI 10.1007/s12098-011-0524-8
SYMPOSIUM ON PGIMER PROTOCOLS ON RESPIRATORY EMERGENCIES
Acute Bronchial Asthma Sudhanshu Grover & Atul Jindal & Arun Bansal & Sunit C. Singhi
Received: 20 April 2011 / Accepted: 30 May 2011 # Dr. K C Chaudhuri Foundation 2011
Abstract Acute asthma is the third commonest cause of pediatric emergency visits at PGIMER. Typically, it presents with acute onset respiratory distress and wheeze in a patient with past or family history of similar episodes. The severity of the acute episode of asthma is judged clinically and categorized as mild, moderate and severe. The initial therapy consists of oxygen, inhaled beta-2 agonists (salbutamol or terbutaline), inhaled budesonide (three doses over 1 h, at 20 min interval) in all and ipratropium bromide and systemic steroids (hydrocortisone or methylprednisolone) in acute severe asthma. Other causes of acute onset wheeze and breathing difficulty such as pneumonia, foreign body, cardiac failure etc. should be ruled out with help of chest radiography and appropriate laboratory investigations in first time wheezers and those not responding to 1 h of inhaled therapy. In case of inadequate response or worsening, intravenous infusion of magnesium sulphate, terbutaline or aminophylline may be used. Magnesium sulphate is the safest and most effective alternative among these. Severe cases may need ICU care and rarely, ventilatory support.
exacerbation of asthma is the 3rd commonest diagnosis after acute diarrhea and seizures among the patients attending pediatric emergency service [2]. Despite advancing knowledge of the pathophysiology and treatment, asthma related morbidity and mortality is on the rise.
Keywords Acute asthma . Children . Inhaled salbutamol . Inhaled budesonide . Magnesium sulphate . Terbutaline infusion
Pathophysiology
Introduction Global prevalence of asthma in childhood ranges between 10% and 30% and is on the rise [1]. At PGIMER, acute S. Grover : A. Jindal : A. Bansal : S. C. Singhi (*) Department of Pediatrics, Advanced Pediatrics Centre, Postgraduate Institute of Medical Education and Research, Chandigarh 160012, India e-mail:
[email protected]
Definition Acute exacerbation of asthma can be defined as episodes of coughing (particularly at night/early morning), wheezing, breathlessness or chest tightness associated with widespread, but variable, airflow obstruction within the lung that is often reversible either spontaneously or with treatment [3, 4]. The term ‘status asthmaticus’ relates severity to the outcome and has been used to define a severe asthmatic exacerbation that does not respond to repetitive or continuous administration of inhaled short-acting β2-adrenergic receptor agonists (SABAs) in the emergency setting [5].
Small airway obstruction within lungs leads to increased airway resistance, reduced expiratory flow, air trapping with each breath and lung hyperinflation. The expiration becomes an active process. Diaphragmatic flattening from hyperinflation causes additional mechanical disadvantages. Both forced expiratory volume and forced vital capacity are decreased and total lung volumes are increased. Gas exchange abnormalities occur because of V/Q mismatch, increased intrapulmonary shunt, and increased dead space (airway over-distension). Dynamic hyperinflation (air trapping with each breath) in severe asthma can stretch the pulmonary vasculature,
Indian J Pediatr
increasing pulmonary vascular resistance and right ventricular afterload. Due to large negative intrathoracic pressure during inspiration, left ventricular afterload is increased, and systolic blood pressure decreases. Exaggerated variation in systolic blood pressure during inspiration is termed as pulsus paradoxus.
Principles of Management Emergency room management of acute asthma includes the following: & & & &
Rapid diagnosis and assessment of the severity based on clinical evaluation Appropriate interventions to relieve breathing difficulty and airway obstruction Assessment of response to the therapy (using clinical asthma severity scores) [6] and Stepping up the therapy to overcome unresponsiveness
Clinical Evaluation and Assessment of Severity A child with acute exacerbation of asthma presents with cough and wheezing, and exhibits signs of dyspnea, increased work of breathing, and anxiety. The sick asthmatic child may also present in respiratory failure or even frank cardiopulmonary arrest. Ominous signs include distant or absent breath sounds (“silent chest”) in the face of increased respiratory effort. While there is no diagnostic test for asthma, a family history of reactive airway disease, a history of recurrent symptoms, and a good response to therapy support the diagnosis. The diagnosis can be difficult in the “first time wheezer” or in a child with atypical symptoms (Table 1). In such patients, pneumonia, bronchiolitis, airway foreign body and congestive heart failure must be rapidly differentiated from asthma. Clinical history should include history of cough, fever, respiratory distress, noisy breathing, whistling sounds, cyanosis and lethargy, past history of asthma, details of treatment, whether on regular treatment, previous hospitalization and if yes, details of treatment, and pointers to rule out foreign body inhalation and pneumonia. In clinical examination, note the respiratory rate, temperature, heart rate, peripheral pulses, blood pressure, pulsus paradoxus, air entry, nasal flaring, retractions, accessory muscle usage, wheeze (phase and length of wheeze), oxygen saturation (off and on oxygen) by pulse oximetry and any abnormality in other systems’ examination. Peak flow and spirometry are useful in older than 5 years and co-operative children (especially if baseline values are known).
Table 1 Differential diagnosis of wheezing in childhood 1. Infection A. Viral • Respiratory syncytial virus/bronchiolitis • Parainfluenza, Influenza, Adenovirus, Rhinovirus, Human metapneumovirus B. Bacterial pneumonia C. Chlamydia 2. Asthmaa 3. Aspiration syndromesa • Gastro-esophageal reflux disease (GERD) 4. Heart diseasea 5. Anatomic abnormalitiesa A. Extrinsic airway anomalies • Vascular ring/sling B. Intrinsic airway anomalies • Airway hemangioma • Cystic adenomatoid malformation • Bronchial lung cyst • Congenital lobar emphysema • Sequestration of lung • Mediastinal lymph node/tumor/TB lymphadenitis C. Malacia of larynx, trachea, or bronchi 6. Foreign body 7. Anaphylaxis 8. Inhalational injuries (burns) 9. Mucociliary clearance disordersa • Cystic fibrosis • Primary ciliary dyskinesia • Bronchiectasis Entities marked
a
are causes of recurrent wheeze
Peak flow measures obstruction in larger airways, spirometry assesses the more peripheral airways. Based on history and clinical examination, the severity of acute asthma may be regarded as mild, moderate and severe (Tables 2 and 3). The same parameters can be used to assess the initial severity and also to monitor the response to therapy. Presence of disturbed level of consciousness (drowsy, confused), inability to speak, markedly diminished or absent breath sounds, central cyanosis, diaphoresis, pulsus paradoxus >20 mm Hg, PEFR 95%
60–80% >60
