Status asthmaticus by Pushpa Raj Sharma
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The correct statement is B. Most devices require a gas flow rate of 10-12 L/min to generate optimal particle size.
Status asthmaticus by Pushpa Raj Sharma
- 1. Status asthmaticus A severe form of asthma
- 2. Hypersecretion Epitheal damage with exposed nerve endings Hypertrophy of goblet cells and mucous glands Status asthmaticus : Pathophysiology
- 3. Pathophysiology Smooth muscle spasm Airway edema Mucous plugging Asthma is primarily an inflammatory disease
- 4. Risk factors for fatal asthma • Medical – Previous attack with rapid/severe deterioration or respiratory failure or seizure/loss of consciousness • Psychosocial – Denial ,non-compliance • Family fear of inhalers
- 5. Lung Mechanics • Hyperinflation – Obstructed small airways cause premature airway closure, leading to air trapping and hyperinflation. • Hypoxemia – Inhomogenous distribution of the affected areas results in V/Q mismatch, mostly shunt.
- 6. Cardiopulmonary interactions • Left ventricular load – Spontaneously breathing children with severe asthma have negative intrapleural pressure as low as -35 cm H2O during almost the entire respiratory cycle. – Negative intrapleural pressure causes increased left ventriculalr after load, resulting in risk for pulmonary edema • Right ventricular load – Hypoxic pulmonary vasoconstriction and lung hyperinflation lead to increased right ventricular after load
- 7. Cardiopulmonary interactions • Pulsus paradoxus – It is the clinical correlate of cardiopulmonary interaction during asthma. It is defined as exaggeration of the normal respiratory drop in systolic BP: • Normally <5 mm Hg, but >10mmHg in pulsus paradoxus
- 8. Pathophysiology Severe air flow obstruction Incomplete exhalation Increased lung volume Expanded small airwaysIncreased elastic recoil pressure Increased expiratory flow Decreased expiratory resistance Compenseted Hyperinflation, normocapnia Worsening airflow obstruction Decompenseted: Severe hyperinflation, hypercapnia
- 9. Metabolism VQ mismatch Increased work of breathing Dehydration Hypoxia Lactate Ketones Metabolic acidosis
- 11. Types of exacerbation • Mild asthma exacerbation – Dyspnea on exertion or tachypnea in young children. – PEF< 70% predicted – Prompt relief with inhaled with short acting beta agonist. – Home management
- 12. Moderate asthma exacerbation • Dyspnea usually limits activity – PEF 40-69% – Relief with frequent inhaled short acting beta agonists – Hospistal/clinic management – Anticipate 1-2 days of symptoms after treatment onset
- 13. Severe exacerbation • Dyspnea at rest, limiting conversation – PEF less than 40% predicted – Only partial relief with inhaled short acting beta 2 agonists – Emergency department management • Hospitalization likely • Systemic corticosteroids and ipratropium • Anticipate > 3 days symptoms
- 14. Life threatening exacerbation • Unable to speak, severe dyspnea with associated diaphoresis – PEF <25% of predicted – Minimal relief with inhaled short acting beta agonist – Emergency stabilazation • PICU admission • Frequent or continuous salbutamol nebs • Systemic Corticosteroid and ipratroprium • ABC management.
- 15. Assessment: impending respiratory failure • Altered level of consciousness • Inability to speak • Absent breath sounds • Central cyanosis • Diaphoresis • Inability to lie down • Marked pulsus paradoxus
- 18. Management • Oxygen 100% warm, humidified – Delver by non breather mask or high flow nasal canula • Nebulized salbutamol with ipratroium continuously to hourly • Systemic corticosteriod • Adrenergic agonists: – Epinephrine – Terbutaline ( alterntive) • Two intravenous line
- 19. Further management (Hypercarbia is a failure of ventilation not oxygenation) • Hypotension – Fluid bolus of normal saline – Chest xray ? Tension pneumothorax (SIADH may be common in severe asthma) • Magnesium 40-75 mg/kg • Consider ketamine • Consider non invasive ventilation: CPAP • Heliox (helium to oxygen60:40) • Avoid aminophylline or theophylline
- 24. Status asthmaticus Why hesitate to intubate the asthmatic child?
- 25. Case scenario 1 • A 6 yr male with previous history of hospital admission for difficulty in breathing without fever and treatment with salbutamol MDI. Re admitted with severe respiratory distress. He is wheezing. RR is 40/min, HR 145/min. He sits upright, leans forward, has retractions and looks very anxious. He correctly tells you his name and phone#, but has to take breath after every few seconds. • Discuss your initial therapeutic approach.
- 26. Case Scenario 1 • Which of the following are mandatory in this child with severe asthma? (you may choose none, more than one or all) – Arterial blood gas analysis (to detect onset of respiratory acidosis) – Continuous pulse oxymetry – Chest radiograph (to rule out penumomediastinum/ thorax – Frequent determination of PFR – Blood count to assess need for anesthetics
- 27. Scenario 2 • When nebulizing drugs during status asthmaticus, the following statement about gas flow rate is correct: A. The higher is the gas flow rate through the nebulizer, the more particles will be deposited in the patient’s alveolar space. B. Most devices require a gas flow rate of 10-12 L/min to generate optimal particle size. C. Gas flow rates above 5L/min should be avoided to maintain laminar flow in the nebulizer output. D. The nebulizer device should not be driven by 100% oxygen.