From the Guidelines
Type 2 respiratory failure should be managed with non-invasive ventilation (NIV) when a pH <7.35, a PaCO2 of ≥6.5 kPa, and RR >23 breaths/min persist or develop after an hour of optimal medical therapy, as recommended by the BTS/ICS guideline for the ventilatory management of acute hypercapnic respiratory failure in adults 1.
Causes and Characterization
Type 2 respiratory failure occurs when the lungs fail to adequately remove carbon dioxide from the blood, resulting in hypercapnia (elevated CO2 levels) with or without hypoxemia (low oxygen levels). This condition is characterized by a PaCO2 greater than 45 mmHg. Common causes include COPD exacerbations, severe asthma, neuromuscular disorders, chest wall deformities, and central nervous system depression from drugs or neurological conditions.
Treatment Approach
Treatment depends on the underlying cause but typically includes:
- Oxygen therapy, carefully titrated to avoid worsening CO2 retention
- Bronchodilators like albuterol (2-4 puffs every 4-6 hours) for airway obstruction
- Corticosteroids such as prednisone (40-60 mg daily for 5-7 days) for inflammatory conditions
- Antibiotics if infection is present
- Non-invasive ventilation like BiPAP, often used to support breathing and reduce work of breathing, with oxygen enrichment adjusted to achieve SaO2 88–92% 1
- In severe cases, intubation and mechanical ventilation may be necessary
Monitoring and Adjustment
Patients should be monitored closely with regular arterial blood gas measurements to assess response to treatment and adjust interventions accordingly. The BTS guideline for oxygen use in adults in healthcare and emergency settings recommends careful monitoring for hypercapnic respiratory failure with respiratory acidosis, which may develop in the course of a hospital admission even if the initial blood gases were satisfactory 1.
Key Considerations
Addressing the underlying cause is crucial, whether that's treating an infection, adjusting medications for COPD, or managing a neuromuscular disorder. For patients with prior hypercapnic failure, low-concentration oxygen treatment should be started with an initial target saturation of 88–92% pending urgent blood gas results 1. The global strategy for the diagnosis, management, and prevention of chronic obstructive lung disease 2017 report emphasizes the importance of minimizing the negative impact of the current exacerbation and preventing subsequent events, with recommendations including short-acting inhaled β2-agonists, systemic corticosteroids, and antibiotics when indicated 1.
From the FDA Drug Label
Chronic Obstructive Pulmonary Disease Associated with Acute Hypercapnia One vial of doxapram (400 mg) should be mixed with 180 mL of dextrose 5% or 10% or normal saline solution (concentration of 2 mg/mL). The infusion should be started at 1 to 2 mg/minute (½ to 1 mL/minute); if indicated, increase to a maximum of 3 mg/minute Arterial blood gases should be determined prior to the onset of doxapram’s administration and at least every half hour during the two hours of infusion to insure against the insidious development of CO2-RETENTION AND ACIDOSIS.
Doxapram can be used in the management of respiratory failure type 2, which is characterized by hypercapnia, often seen in patients with chronic obstructive pulmonary disease (COPD). The recommended dosage is an infusion of 1 to 2 mg/minute, which can be increased to a maximum of 3 mg/minute if necessary, with close monitoring of arterial blood gases 2.
From the Research
Definition and Management of Respiratory Failure Type 2
- Respiratory failure type 2 is characterized by high carbon dioxide levels (PaCO2 >6kPa) 3
- Non-invasive ventilation (NIV) is the current standard of care for acute type 2 respiratory failure, but it has a high failure rate 3
- High flow nasal therapy (HFNT) has potential additional benefits such as CO2 clearance, the ability to communicate and comfort 3
Treatment Options for Respiratory Failure Type 2
- Non-invasive ventilation (NIV) in the management of acute type 2 respiratory failure in patients with chronic obstructive pulmonary disease (COPD) represents one of the major technical advances in respiratory care over the last decade 4
- High flow nasal cannula oxygen (HFNC) seems superior to conventional oxygen therapy (COT) as a means of avoiding intubation and may therefore be used as a first-line noninvasive respiratory support in patients requiring more than 6 L/min of oxygen or PaO2/FiO2 ≤ 200 mm Hg and a respiratory rate above 25 breaths/minute or clinical signs of respiratory distress 5
- Continuous positive airway pressure (CPAP) cannot currently be recommended as a first-line noninvasive respiratory support, since its beneficial effects on intubation remain uncertain 5
Predictors of Failure for Non-Invasive Ventilation
- Respiratory frequency >25 rpm, higher APACHE II scores, BiPAP use and chronic obstructive pulmonary disease diagnosis were associated with endotracheal intubation 6
- Higher GCS and SpO2 values were associated with NIV success 6
- Reduced APACHE II scores and lower peripheral oxygen saturation were observed in patients who progressed to intubation 6