From the Guidelines
NIV treatment can be considered effective with an average EtCO2 of 45 mmHg on capnography, as this level indicates mild hypercapnia and is often an appropriate target for patients with chronic CO2 retention, such as those with COPD. According to the 2018 GOLD report 1, Noninvasive Positive Pressure Ventilation (NIPPV) is recommended as first-line therapy in instances of hypercapnic respiratory failure (PCO2 > 45 mm Hg and arterial pH 7.35). This suggests that an EtCO2 of 45 mmHg is at the threshold of what is considered hypercapnic respiratory failure, and NIV can be effective in managing such conditions.
When implementing NIV, it is essential to start with low pressure settings (IPAP 8-12 cmH2O, EPAP 4-5 cmH2O) and titrate upward based on patient comfort and response. Monitoring the patient closely is crucial, as stable EtCO2 levels around 45 mmHg may be acceptable, but rising levels indicate worsening ventilation that may require adjustment of NIV settings or consideration of invasive ventilation. The effectiveness of NIV should be assessed through multiple parameters, including:
- Respiratory rate
- Work of breathing
- Oxygen saturation
- Patient comfort Not just EtCO2 alone, as NIV works by reducing work of breathing, improving alveolar ventilation, and recruiting collapsed alveoli, which helps normalize CO2 levels while supporting oxygenation. As noted in the 2018 GOLD report 1, NIPPV successfully improves oxygenation, pH, and work of breathing with large decreases in mortality and intubation rates, making it a valuable treatment option for patients with hypercapnic respiratory failure.
From the Research
Effectiveness of NIV Treatment with Average EtCO2 of 45 mmHg
- The effectiveness of Non-Invasive Ventilation (NIV) treatment with an average End-Tidal Carbon Dioxide (EtCO2) level of 45 mmHg on capnography is a topic of interest in respiratory care.
- According to a study published in 2015 2, measuring EtCO2 using a dedicated naso-buccal sensor during NIV was inaccurate to predict both PaCO2 and PaCO2 variations over time.
- Another study from 2021 3 compared ETCO2 values and blood gas PCO2 values in patients receiving NIV treatment in the emergency department, finding a significant difference between the two values, suggesting that ETCO2 cannot be used instead of PCO2.
- A 2014 review 4 recommended capnography as a non-invasive method to assess adequacy of ventilation in non-intubated patients, but did not specifically address the effectiveness of NIV treatment with an average EtCO2 of 45 mmHg.
- It is worth noting that the study from 2016 5 defined nocturnal hypoventilation as a mean nighttime TcPCO2 ≥50 mm Hg, which is higher than the average EtCO2 of 45 mmHg in question.
- Overall, the available evidence suggests that an average EtCO2 of 45 mmHg may not be a reliable indicator of the effectiveness of NIV treatment, and further monitoring and assessment may be necessary to determine the treatment's efficacy 2, 3.
Monitoring and Assessment
- Capnography can be a useful tool in monitoring patients receiving NIV treatment, as it provides information on the patient's ventilatory status 6, 4.
- However, the accuracy of EtCO2 measurements can be affected by various factors, such as the type of sensor used and the patient's respiratory condition 2, 3.
- Therefore, it is essential to consider multiple factors and monitoring parameters when assessing the effectiveness of NIV treatment, rather than relying solely on EtCO2 values 5, 6.