Physiologic Risks of Intubating Asthmatics

Key Physiologic Risks

Asthmatic patients have prolonged expiratory time requirements due to bronchoconstriction, which can lead to incomplete exhalation, air trapping, and auto-PEEP when mechanically ventilated, according to the American Thoracic Society 1
Hypotension commonly accompanies the initiation of positive pressure ventilation in asthmatic patients, and intravascular volume should be maintained or replaced, as recommended by the American College of Chest Physicians 2
High ventilator pressures associated with mechanical ventilation in asthmatics significantly increase the risk of pneumothorax, pneumomediastinum, and subcutaneous emphysema, as reported by the American College of Chest Physicians 2
The combination of auto-PEEP, reduced venous return, and hypotension can lead to cardiovascular collapse during or immediately after intubation, according to the American Thoracic Society 1

Intubation should be considered in patients with persistent or increasing hypercapnia, exhaustion, and depressed mental status, as recommended by the American College of Chest Physicians 2
Patients presenting with apnea or coma should be intubated immediately, according to the American Heart Association 2
Intubation should be performed semielectively before respiratory arrest occurs, as delaying intubation until cardiorespiratory arrest significantly increases mortality, as reported by the American College of Chest Physicians 2

The largest endotracheal tube available (usually 8 or 9 mm) should be used to decrease airway resistance, as recommended by the American Society of Anesthesiologists 1
The most expert available doctor (ideally an anaesthetist) should perform the intubation to minimize complications, according to the British Thoracic Society 3
Adequate intravascular volume should be ensured before intubation to mitigate hypotension, as recommended by the American College of Chest Physicians 2

A "controlled hypoventilation" strategy should be used to provide adequate oxygenation while minimizing airway pressures and the possibility of barotrauma, as recommended by the American Thoracic Society 2
Ventilator settings should include slower respiratory rates (10-14 breaths/min), smaller tidal volumes (6-8 mL/kg), shorter inspiratory times (inspiratory flow rate 80-100 L/min), and longer expiratory times (I:E ratio 1:4 or 1:5), according to the American Association for Respiratory Care 1
Regular assessment for signs of auto-PEEP is necessary, as it can lead to complications such as hyperinflation, tension pneumothorax, and hypotension, as reported by the American Thoracic Society 1

Sufficient sedation should be provided to prevent ventilator dyssynchrony, which can worsen air trapping, as recommended by the Society of Critical Care Medicine 1
Propofol infusion (5-50 mcg/kg/min) can be used as the primary agent, with fentanyl for analgesia and midazolam as a complementary sedative if necessary, according to the American Society of Anesthesiologists 4
Paralytic agents can be considered if auto-PEEP persists despite adequate sedation, as reported by the American Thoracic Society 1

If auto-PEEP develops, high-end expiratory pressure should be quickly reduced by briefly disconnecting the patient from the ventilator circuit to allow PEEP to dissipate during passive exhalation, as recommended by the American Association for Respiratory Care 1
Signs of tension pneumothorax should be vigilantly monitored, as it requires immediate decompression, according to the American College of Chest Physicians 1

Conventional ventilator settings designed for non-asthmatic patients should never be used, as these can worsen air trapping, as reported by the American Thoracic Society 1
High respiratory rates and large tidal volumes should be avoided, as they can lead to incomplete exhalation and auto-PEEP, according to the American Association for Respiratory Care 1
Inadequate sedation can lead to patient-ventilator dyssynchrony and worsen air trapping, as recommended by the Society of Critical Care Medicine 4
Delayed expert consultation should be avoided, and expert consultation should be obtained early for management of mechanical ventilation in severe asthma, as reported by the American Thoracic Society 1

The American Thoracic Society recommends nebulized albuterol 5-10 mg via oxygen-driven nebulizer, repeated frequently, for intubated asthma patients to improve bronchodilation 5
The British Thoracic Society suggests adding ipratropium 0.5 mg to nebulizer and repeating every 6 hours to enhance bronchodilatory effects 5
The use of intravenous hydrocortisone 200 mg every 6 hours is recommended for seriously ill or vomiting patients to reduce inflammation 5
Subcutaneous epinephrine or terbutaline (250 mcg over 10 minutes) may be considered in intubated patients not responding to inhaled therapy to improve bronchodilation 5

Regular assessment of arterial blood gases is necessary to evaluate oxygenation and ventilation adequacy in intubated asthma patients 5
Monitoring of plasma electrolytes, urea, and blood count is essential to detect potential complications 5
Chest radiography should be obtained to exclude pneumothorax, consolidation, or pulmonary edema in intubated asthma patients 5
The administration of antibiotics should be avoided unless bacterial infection is documented to prevent unnecessary antibiotic use 5
Sedation should not be used in non-intubated patients, as it is contraindicated, and percussive physiotherapy should be avoided as it is unnecessary 5