Monitoring Long Term Noninvasive Ventilation: Benefits, Caveats and Perspectives

Abstract

Long term noninvasive ventilation (LTNIV) is a recognized treatment for chronic hypercapnic respiratory failure (CHRF). COPD, obesity-hypoventilation syndrome, neuromuscular disorders, various restrictive disorders, and patients with sleep-disordered breathing are the major groups concerned. The purpose of this narrative review is to summarize current knowledge in the field of monitoring during home ventilation. LTNIV improves symptoms related to CHRF, diurnal and nocturnal blood gases, survival, and health-related quality of life. Initially, patients with LTNIV were most often followed through elective short in-hospital stays to ensure patient comfort, correction of daytime blood gases and nocturnal oxygenation, and control of nocturnal respiratory events. Because of the widespread use of LTNIV, elective in-hospital monitoring has become logistically problematic, time consuming, and costly. LTNIV devices presently have a built-in software which records compliance, leaks, tidal volume, minute ventilation, cycles triggered and cycled by the patient and provides detailed pressure and flow curves. Although the engineering behind this information is remarkable, the quality and reliability of certain signals may vary. Interpretation of the curves provided requires a certain level of training. Coupling ventilator software with nocturnal pulse oximetry or transcutaneous capnography performed at the patient's home can however provide important information and allow adjustments of ventilator settings thus potentially avoiding hospital admissions. Strategies have been described to combine different tools for optimal detection of an inefficient ventilation. Recent devices also allow adapting certain parameters at a distance (pressure support, expiratory positive airway pressure, back-up respiratory rate), thus allowing progressive changes in these settings for increased patient comfort and tolerance, and reducing the requirement for in-hospital titration. Because we live in a connected world, analyzing large groups of patients through treatment of “big data” will probably improve our knowledge of clinical pathways of our patients, and factors associated with treatment success or failure, adherence and efficacy. This approach provides a useful add-on to randomized controlled studies and allows generating hypotheses for better management of HMV.

Monitoring Systems in Home Ventilation

“…Some authors use raw values such as maximum PtcCO 2 > 49 mmHg [ 21 ], or mean PtcCO 2 > 50 mmHg [ 11 , 22 ], while others use a change in PtcCO 2 from baseline to a maximum value above 7.5 or 10 mmHg [ 25 , 29 ]. However, the optimal clinical threshold for defining nocturnal hypoventilation may differ according to the device used, the method of use (e.g., calibration or drift correction), the clinical condition (COPD, SOH, or neuromuscular disorders), the baseline PtcCO 2 , and the clinical setting (patient in spontaneous breathing or on NIV) [ 2 , 22 ]. Due to all the limitations surrounding statistics, a visual inspection of the changes in PtcCO 2 during the night may better indicate nocturnal hypoventilation or hyperventilation ( Figure 6 ).…”

“…However, interpretation of the recording remains manual and requires time and expertise. While some specialized centers use polygraphy for titration and follow-up, most authors recommend performing polygraphy in selected patients [ 2 ]. Upper airway obstructions are detected by the inbuilt ventilator software with relative accuracy for stable patients with obesity hypoventilation syndrome in the absence of unintentional leaks [ 7 , 8 ].…”

“…NIV requires regular monitoring to optimize the ventilator settings during the initiation period and to readjust them when the lung condition changes over time. In addition, problems such as unintentional leaks, upper airway obstructions, and patient–ventilator asynchrony may occur and impair treatment quality [ 2 ]. The overall efficacy of the treatment is assessed by monitoring the clinical symptoms of nocturnal hypoventilation, as well as the daytime measurement of blood gas exchanges.…”

Practical Guide to Management of Long-Term Noninvasive Ventilation for Adults With Chronic Neuromuscular Disease

“…Recent technological advances have dramatically improved access to quantitative data on respiratory pump dysfunction and respiratory device performance. 47,48 We employ 4 primary monitoring modalities: respiratory symptom assessment; selected measures of pulmonary function; blood gases; and respiratory device telemonitoring.…”

“…Transcutaneous measurement of PCO2 (PtcCO2) is generally considered more accurate than end-tidal PCO2 measurement 78 and can be used for monitoring during mask or mouthpiece ventilation. 48,75,79 Two companies manufacture transcutaneous blood gas monitoring devices are currently available in the U.S.…”