What are the management strategies to reduce mortality in pediatric patients intubated for status asthmaticus?

Mortality in Pediatric Patients Intubated for Status Asthmaticus

Mortality in intubated pediatric status asthmaticus patients is primarily reduced by avoiding intubation whenever possible through aggressive medical management, and when mechanical ventilation becomes unavoidable, using a controlled hypoventilation strategy with permissive hypercapnia to prevent barotrauma and cardiovascular collapse. 1

Critical Understanding: Intubation Worsens the Underlying Pathophysiology

• Mechanical ventilation should be avoided if at all possible because the underlying dynamic hyperinflation will worsen with positive-pressure ventilation, increasing mortality risk 1
• The goal of all management is restoration of adequate pulmonary function and avoidance of mechanical ventilation 2
• Intubation in status asthmaticus carries significant mortality risk due to worsening air trapping, barotrauma, and hemodynamic compromise 1, 3

Pre-Intubation Strategies to Reduce Mortality

Aggressive Medical Management to Avoid Intubation

First-line therapies (must be maximized):

• High-flow oxygen via face mask to maintain SaO₂ >92% 4
• Nebulized β-agonists (salbutamol 5 mg or terbutaline 10 mg) up to every 30 minutes 4, 5
• Ipratropium bromide 100 mcg nebulized every 6 hours added to β-agonist therapy 4, 5
• Intravenous hydrocortisone or oral prednisolone 1-2 mg/kg (maximum 40 mg) 4

Second-line therapies when life-threatening features present:

• Intravenous aminophylline 5 mg/kg over 20 minutes followed by 1 mg/kg/h maintenance infusion (omit loading dose if already on oral theophyllines) 4, 5
• Intravenous magnesium sulfate 5
• Intravenous terbutaline 250 mcg over 10 minutes as alternative 5

Indications for ICU Transfer with Preparation for Intubation

Transfer to intensive care with a physician prepared to intubate when: 6, 5

• Deteriorating peak expiratory flow despite aggressive medical management 6
• Persistent or worsening hypoxia (PaO₂ <60 mmHg) despite 60% inspired oxygen 6
• Rising hypercapnia (PaCO₂ >45 mmHg) indicating impending respiratory failure 6
• Exhaustion with feeble respirations 4, 6
• Altered mental status (confusion, drowsiness, coma) 4, 6
• Respiratory arrest 4, 6

Critical arterial blood gas markers:

• Normal or elevated PaCO₂ in a breathless asthmatic is paradoxical and indicates the patient can no longer hyperventilate to compensate 6
• Low pH indicating respiratory acidosis 6

Intubation Technique to Minimize Mortality

Pre-intubation preparation:

• Ensure adequate intravascular volume before intubation to mitigate hypotension, which is a major cause of peri-intubation mortality 6
• Have the most expert available physician (ideally an anesthetist) perform the intubation 4
• Do not attempt intubation until the most expert available doctor is present 4

Technical considerations:

• Use the largest endotracheal tube available (usually 8-9 mm in adults; appropriately sized for children) to decrease airway resistance 6

Post-Intubation Ventilation Strategy to Reduce Mortality

The controlled hypoventilation strategy is essential to prevent death from barotrauma and cardiovascular collapse: 6, 1

Specific ventilator settings:

• Slower respiratory rates: 10-14 breaths/min 6
• Smaller tidal volumes: 6-8 mL/kg 6
• Shorter inspiratory times with high inspiratory flow rates (80-100 L/min) 6
• Longer expiratory times with I:E ratio of 1:4 or 1:5 to allow adequate exhalation and prevent air trapping 6
• Accept permissive hypercapnia while maintaining adequate oxygenation 6, 1

Critical management points:

• Sufficient sedation is necessary to prevent ventilator dyssynchrony, which worsens air trapping and increases mortality 6
• If intubated patient's condition deteriorates, consider DOPE mnemonic: Displacement of tube, Obstruction of tube, Pneumothorax, Equipment failure 4
• Use controlled hypoventilation with low tidal volume and long expiratory time to lessen risk of barotrauma and hypotension 1

Monitoring to Prevent Mortality

• Continuously monitor vital signs, oxygen saturation, and peak expiratory flow 5
• Arrange chest radiography to exclude pneumothorax, consolidation, or pulmonary edema 5
• Check plasma electrolytes and blood count 5
• Use exhaled CO₂ detection (capnography or colorimetry) to confirm tube position in children with perfusing rhythm 4

Common Pitfalls That Increase Mortality

• Attempting intubation without adequate volume resuscitation leads to cardiovascular collapse 6
• Using conventional ventilation strategies (normal tidal volumes, normal respiratory rates) worsens dynamic hyperinflation and causes barotrauma 1, 3
• Inadequate sedation causes ventilator dyssynchrony, worsening air trapping and increasing mortality risk 6
• Delaying aggressive medical management before intubation becomes necessary 4, 7
• Sedation is contraindicated in severe asthma prior to intubation as it can precipitate respiratory arrest 5