High‐pressure NIV ups cycle endurance time, eases exertional dyspnoea in COPD patients with CHRF
Oxygen supplementation with high-pressure noninvasive ventilation (NIV) during exercise improves cycle endurance time, moderates exertional dyspnoea and limits exercise-induced hypercapnia in chronic obstructive pulmonary disease (COPD) patients with chronic hypercapnic respiratory failure (CHRF), according to a recent study.
Researchers conducted two cycle endurances tests (CET) at 60 percent of the peak work rate and randomized patients to cycle in two conditions: (1) high-pressure NIV (mean inspiratory positive airway pressure, 27±3 cm H2O) along with oxygen supplementation or (2) control (oxygen-use only).
The following measures were recorded continuously: transcutaneously measured partial pressure of carbon dioxide (TcPCO2), oxygen saturation and heart rate. Near-infrared spectroscopy (NIRS) was used to measure muscle oxygen availability of intercostal and vastus lateralis muscle during exercise.
Twenty patients with CHRF (forced expiratory volume in 1 s [FEV1], 19±4 percent predicted; partial pressure of oxygen [PaO2], 55±9 mm Hg; partial pressure of carbon dioxide [PaCO2], 51±7 mm Hg) participated in this randomized crossover trial.
COPD patients on NIV had 39-percent higher cycle endurance time than those on oxygen-use only (663±360 vs 477±249 s; p=0.013), as well as significantly lower TcPCO2 at rest (44.9±6.2 vs 50.7±6.6 mm Hg; p<0.001) and at isotime (50.0±5.5 vs 56.1±6.2 mm Hg; p<0.001).
There was a relatively constant availability of oxygen in the intercostal muscles with NIV compared to oxygen-use only. In addition, patients using NIV cycled longer but reported a lower increase in exertional dyspnoea at the end of CET (median increase in Borg-dyspnoea, 2 vs 4; p=0.003).
“Patients with COPD and CHRF characteristically have exercise intolerance and limitations in performing conventional training,” the authors said.