Validation of the AVAPS AE Algorithm in Chronic Obstructive Pulmonary Disease (COPD) Patients

Overview

COPD continues to be a cause of major morbidity for patients. Those patients who also have respiratory failure and obstructive sleep apnoea are at higher risk of exacerbations and death and have worse health related quality of life than similar COPD patients without respiratory failure. Treatment options in this group of patients have been limited and data to support the use of machines to assist breathing (non-invasive ventilators) in stable patients are limited. A major limitation of these devices has been patient acceptance and achieving sufficient control of sleep breathing disturbance. Currently devices are set at a fixed pressure to support the breathing throughout the night. The new software within the trial device will aim to better match the support provided by the machine to that needed by the patient. It is hoped that this may offer enhanced comfort as well as superior control of respiratory failure.

Chronic Obstructive Pulmonary Disease (COPD) is a major cause of morbidity and mortality worldwide. Treatment options for COPD patients consist of medications, such as bronchodilators and anti-inflammatory drugs, pulmonary rehabilitation, long term oxygen therapy (LTOT), lung volume reduction surgery and lung transplantation. Studies have shown that bronchodilators and anti-inflammatory drugs show minor or no benefit on long term outcomes but rather are used mainly for symptomatic relief.1 Pulmonary rehabilitation has been demonstrated to improve functional status and symptoms but there is lacking evidence on long term outcomes of this therapy. 2 Lung volume reduction surgery and lung transplantation is only appropriate for a small number of patients; therefore, there is no demonstration of improved long-term survival rate.3, 4 Of these available therapies, few have been shown to significantly improve long term patient outcomes. For the severe COPD patient, LTOT is the only treatment that demonstrated prolonged survival in controlled studies. 5, 6 But, despite the effectiveness of LTOT, COPD is still characterized by a high morbidity and mortality rate. Although the treatment of OSA with CPAP therapy has been associated with reduced hospital admissions and exacerbations there are possible adverse consequences on pulmonary mechanics due to exacerbating hyperinflation. Noninvasive positive pressure ventilation (NPPV) is one therapy that may prove beneficial to stable COPD patients. NPPV is the use of positive pressure ventilation administered via a nasal or full face mask (that covers both the nose and mouth). This type of ventilation has become a well established and increasingly used therapeutic option for patients with hypercapnic respiratory failure (HRF) due to COPD.7 NPPV, used nocturnally, may improve nighttime hypoventilation that is common with COPD patients. An improvement in nocturnal hypoventilation would reset the respiratory center sensitivity for CO2.8 9 This would result in an improvement in daytime gas exchange and sleep quality. It is also known that hyperinflation in patients with COPD increases their work of breathing, thus fatiguing the respiratory muscles.10 It has been suggested that by applying nocturnal NPPV it would allow the respiratory muscles to rest, resulting in muscle function recovery, increased muscle strength, reduced tendency for fatigue and improvement in pulmonary function and gas exchange.11 AVAPS AE AVAPS AE is a mode of therapy (Philips Respironics Inc, Monroeville, PA, USA) with potential advantages over the currently established modes of noninvasive positive pressure ventilation (CPAP and bilevel therapy). This mode of therapy incorporates AVAPS (automated adjustable IPAP setting to maintain target ventilation with a settable rate of change), AutoEPAP and Auto Back up Rate. In particular the automated EPAP algorithm will ensure optimal upper airway patency without exacerbating hyperinflation. In this study, we are evaluating the AVAPS AE mode as compared to the participant's current mode of ventilation. We believe that these automated parameters will allow better nocturnal ventilatory control to offset the differing elastic and resistive loads imposed by changes in body position during sleep. Furthermore, AVAPS AE will counter the changing ventilatory requirements due to alterations in lung volumes and airway resistance during different stages of sleep. In summary, the AVAPS AE mode will enable automatic adjustment in response to ventilatory changes throughout the night. Study Objective The objective of this study is to validate the performance of the AVAPS AE therapy in COPD-OSA overlap patients during nocturnal ventilation.