December 31, 2018
There are 2 hypotheses on why high-intensity NIV is beneficial to individuals with hypercapnic stable COPD.
There is evidence that people with comorbid stable chronic obstructive pulmonary disease (COPD) and chronic hypercapnic respiratory failure (CHRF) have improved symptoms and survival rates with high-intensity noninvasive ventilation (NIV), according to a review recently published in Respirology.
Researchers examined two previously conducted parallel-group, randomized controlled trials, as well the results of their own 2-year randomized controlled trial. High-intensity NIV was beneficial in patients with more acute COPD and chronic hypercapnia, and the higher survival rate in those treated with this method compared with standard care may compensate for the B-level evidence in terms of clinical recommendation. Recommended settings are still unspecified, however, since causality has not been determined between mechanisms and outcomes such as CO2 reduction.
There are 2 leading hypotheses on why high-intensity NIV is beneficial to individuals with hypercapnic stable COPD. One derives from the possibility that NIV improves the imbalance between respiratory load and inspiratory muscle capacity that may trigger CHRF. Alternatively, it has been suggested that high-intensity NIV boosts respiration, which counteracts hypercapnia. This is supported by evidence that both daytime breathing patterns and nighttime gas exchange improve with this treatment, thereby decreasing partial arterial CO2.
Although further research is needed to determine best practices, the reviewers underlined the important of step-wise titration during several days to ensure satisfactory partial arterial CO2 reduction, comfort, and tolerability in patients. It is recommended that practitioners begin with practice sessions during the day, setting inspiratory positive airway pressure levels to 12-18 cm H2O and low backup respiratory rate and expiratory positive airway pressure (3-6 cm H2O). On the first practice session, slowly increase inspiratory pressure until the patient can no longer tolerate it. When a comfortable and efficacious setting is found, move to nocturnal use and repeat monitoring to fine-tune the settings for maximal results.
The study researchers concluded, “Practically, [high-intensity] NIV setting is ‘personalized medicine’, targeting normocapnia or a maximal reduction in [partial arterial] CO2. To achieve this, reliable awake and nocturnal gas exchange monitoring are needed. Ventilator data can assist with monitoring of compliance, with cautious interpretation of leak, tidal volumes and residual respiratory events.”
Reference
van der Leest S, Duiverman ML. High-intensity non-invasive ventilation in stable hypercapnic COPD: evidence of efficacy and practical advice [published online November 30, 2018]. Respirology. doi:10.1111/resp.13450