Olivier Contal

Monitoring of noninvasive ventilation by built-in software of home bilevel ventilators: a bench study.

BACKGROUND Current bilevel positive-pressure ventilators for home noninvasive ventilation (NIV) provide physicians with software that records items important for patient monitoring, such as compliance, tidal volume (Vt), and leaks. However, to our knowledge, the validity of this information has not yet been independently assessed. METHODS Testing was done for seven home ventilators on a bench model adapted to simulate NIV and generate unintentional leaks (ie, other than of the mask exhalation valve). Five levels of leaks were simulated using a computer-driven solenoid valve (0-60 L/min) at different levels of inspiratory pressure (15 and 25 cm H(2)O) and at a fixed expiratory pressure (5 cm H(2)O), for a total of 10 conditions. Bench data were compared with results retrieved from ventilator software for leaks and Vt. RESULTS For assessing leaks, three of the devices tested were highly reliable, with a small bias (0.3-0.9 L/min), narrow limits of agreement (LA), and high correlations (R(2), 0.993-0.997) when comparing ventilator software and bench results; conversely, for four ventilators, bias ranged from -6.0 L/min to -25.9 L/min, exceeding -10 L/min for two devices, with wide LA and lower correlations (R(2), 0.70-0.98). Bias for leaks increased markedly with the importance of leaks in three devices. Vt was underestimated by all devices, and bias (range, 66-236 mL) increased with higher insufflation pressures. Only two devices had a bias < 100 mL, with all testing conditions considered. CONCLUSIONS Physicians monitoring patients who use home ventilation must be aware of differences in the estimation of leaks and Vt by ventilator software. Also, leaks are reported in different ways according to the device used.

Impact of Different Backup Respiratory Rates on the Efficacy of Noninvasive Positive Pressure Ventilation in Obesity Hypoventilation Syndrome: A Randomized Trial

BACKGROUND Unintentional leaks, patient-ventilatory asynchrony, and obstructive or central events (either residual or induced by noninvasive positive pressure ventilation [NPPV]) occur in patients treated with NPPV, but the impact of ventilator settings on these disturbances has been little explored. The objective of this study was to investigate the impact of backup respiratory rate (BURR) settings on the efficacy of ventilation, sleep structure, subjective sleep quality, and respiratory events in a group of patients with obesity hypoventilation syndrome (OHS). METHODS Ten stable patients with OHS treated with long-term nocturnal NPPV underwent polysomnographic recordings and transcutaneous capnography on 3 consecutive nights with three different settings for BURR in random order: spontaneous (S) mode, low BURR, and high BURR. No other ventilator parameter was modified. RESULTS The S mode was associated with the occurrence of a highly significant increase in respiratory events, mainly of central and mixed origin, when compared with both spontaneous/timed (S/T) modes. Accordingly, the oxygen desaturation index was significantly higher in the S mode than in either of the S/T modes. The results of nocturnal transcutaneous P(CO(2)) (Ptc(CO(2))) (mean value and time spent with Ptc(CO(2)) > 50 mm Hg) were similar over the three consecutive nocturnal recordings. The quality of sleep was perceived as slightly better, and the number of perceived arousals as lower with the low- vs high-BURR (S/T) mode. CONCLUSIONS In a homogenous group of patients treated with long-term NPPV for obesity-hypoventilation, changing BURR from an S/T mode with a high or low BURR to an S mode was associated with the occurrence of a highly significant increase in respiratory events, of mainly central and mixed origin. TRIAL REGISTRY ClinicalTrials.gov; No.: NCT01130090; URL: www.clinicaltrials.gov

Original ResearchRespiratory CareMonitoring of Noninvasive Ventilation by Built-in Software of Home Bilevel Ventilators: A Bench Study

BACKGROUND Current bilevel positive-pressure ventilators for home noninvasive ventilation (NIV) provide physicians with software that records items important for patient monitoring, such as compliance, tidal volume (Vt), and leaks. However, to our knowledge, the validity of this information has not yet been independently assessed. METHODS Testing was done for seven home ventilators on a bench model adapted to simulate NIV and generate unintentional leaks (ie, other than of the mask exhalation valve). Five levels of leaks were simulated using a computer-driven solenoid valve (0-60 L/min) at different levels of inspiratory pressure (15 and 25 cm H(2)O) and at a fixed expiratory pressure (5 cm H(2)O), for a total of 10 conditions. Bench data were compared with results retrieved from ventilator software for leaks and Vt. RESULTS For assessing leaks, three of the devices tested were highly reliable, with a small bias (0.3-0.9 L/min), narrow limits of agreement (LA), and high correlations (R(2), 0.993-0.997) when comparing ventilator software and bench results; conversely, for four ventilators, bias ranged from -6.0 L/min to -25.9 L/min, exceeding -10 L/min for two devices, with wide LA and lower correlations (R(2), 0.70-0.98). Bias for leaks increased markedly with the importance of leaks in three devices. Vt was underestimated by all devices, and bias (range, 66-236 mL) increased with higher insufflation pressures. Only two devices had a bias < 100 mL, with all testing conditions considered. CONCLUSIONS Physicians monitoring patients who use home ventilation must be aware of differences in the estimation of leaks and Vt by ventilator software. Also, leaks are reported in different ways according to the device used.

Sleep in ventilatory failure in restrictive thoracic disorders. Effects of treatment with non invasive ventilation

STUDY OBJECTIVES Hypercapnic ventilatory failure due to restrictive disorders may have a negative impact on sleep architecture. Non-invasive ventilation (NIV) may improve arterial blood gases but may adversely affect sleep. We assessed sleep structure and blood gases before and during NIV in patients with restrictive disorders in hypercapnic ventilatory failure. DESIGN Retrospective cohort study. SETTING Sleep laboratory of Saint-Luc University Hospital (Belgium). PATIENTS Chart review of all patients with predominantly restrictive disorders and respiratory failure seen between 1987 and 2008 and evaluated with a baseline polysomnography (PSG) and a PSG under NIV. MEASUREMENTS AND RESULTS Sixty patients aged (mean±SD) 48±20 years, with total lung capacity of 57±20% of predicted value, PaO(2) of 62±16 mm Hg and PaCO(2) 54±10 mm Hg, were included. At baseline, total sleep time, sleep efficiency, slow wave and rapid-eye movement (REM) sleep were markedly decreased. Conversely, micro-arousals and stage I sleep (N1) were increased. NIV administered with volume-cycled (53%) or pressure-cycled (47%) ventilators improved daytime PaO(2), PaCO(2), pH and HCO(3)(-). In addition, sleep efficiency, REM sleep, mean and lowest nocturnal SpO(2) increased while stage 1, sleep fragmentation, and oxygen desaturation index decreased significantly. CONCLUSION Hypercapnic ventilatory failure in restrictive disorders profoundly affects sleep quality. NIV can improve not only blood gases, but also sleep architecture.

Pulse wave amplitude reduction: a surrogate marker of micro-arousals associated with respiratory events occurring under non-invasive ventilation?

INTRODUCTION Respiratory events occurring under non-invasive ventilation (NIV) may produce sleep fragmentation. Alternatives to polysomnography (PSG) should be validated for providing simple monitoring tools for patients treated at home with NIV. OBJECTIVES To study the value of pulse wave amplitude (PWA) reduction as a surrogate marker of cortical micro-arousals associated with respiratory events occurring during NIV. METHODS 27 PSG tracings under NIV recorded in 9 stable patients with Obesity Hypoventilation Syndrome (OHS), under 3 different ventilator modes (no back-up rate, low or high back-up rate) were analyzed. For all respiratory events (obstructive, central, or mixed event), the association with EEG-micro-arousals, PWA reduction of more than 30% and the presence of associated SpO2 desaturation ≥ 4% was recorded. RESULTS 2474 respiratory events during NREM sleep were analyzed. 73.6% were associated with an EEG-MA, 91.4% with a ≥ 4% decrease in SpO2, and 74.9% with a significant PWA reduction. Sensitivity of PWA for the detection of an EEG-micro-arousal related to a respiratory event was 89.1% [95%CI: 76.7-95.3]. Positive predictive value (PPV) was 87.0% [95%CI: 75.0-94.0]. Sensitivity of PWA was highest in the S mode, compared to both other S/T modes, p = <0.001. Sensitivity of PWA was also higher for central and mixed events, compared to obstructive respiratory events, p = <0.05. CONCLUSIONS PWA reduction is a sensitive marker with a high PPV for the detection of EEG-MA associated with respiratory events during NREM sleep in stable OHS patients treated by NIV. In this situation, PWA could be used to improve scoring of hypopneas and allow an appropriate assessment of sleep fragmentation related to respiratory events.

Pulse transit time as a measure of respiratory effort under noninvasive ventilation

Among the respiratory events that may occur during nocturnal noninvasive ventilation (NIV), differentiating between central and obstructive events requires appropriate indicators of respiratory effort. The aim of the present study was to assess pulse transit time (PTT) as an indicator of respiratory effort under NIV in comparison with oesophageal pressure (Poes). During wakefulness, PTT was compared to Poes during spontaneous breathing and under NIV with or without induced leaks in 11 healthy individuals. In addition, the contribution of PTT versus Poes to differentiation of central from obstructive respiratory events occurring under NIV during sleep was evaluated in 10 patients with obesity hypoventilation syndrome (OHS). From spontaneous breathing to NIV without leaks, respiratory effort decreased significantly whereas, with increasing level of leaks, there was a significant increase in respiratory effort. Changes in PTT accurately reflected changes in Poes. In OHS patients during nocturnal NIV, intraclass correlation coefficients between Poes and PTT were 0.970 for total number of events and 0.970 for percentage of central events. PTT accurately reflects the unloading of respiratory muscles induced by NIV and the increase in respiratory effort during leaks. PTT during sleep is also useful to differentiate central from obstructive respiratory events occurring under NIV.

Reliability of Apnea-Hypopnea Index Measured by a Home Bi-Level Pressure Support Ventilator Versus a Polysomnographic Assessment

BACKGROUND: Ventilators designed for home care provide clinicians with built-in software that records items such as compliance, leaks, average tidal volume, total ventilation, and indices of residual apnea and hypopnea. Recent studies have showed, however, an important variability between devices regarding reliability of data provided. In this study, we aimed to compare apnea-hypopnea indices (AHI) provided by home ventilators (AHINIV) versus data scored manually during polysomnography (AHIPSG) in subjects on noninvasive ventilation (NIV) for obesity-hypoventilation syndrome. METHODS: Stable subjects with obesity-hypoventilation syndrome on NIV, all using the same device, underwent 3 consecutive polysomnographic sleep studies with different backup breathing frequencies (spontaneous mode, low and high backup breathing frequencies). During each recording, AHINIV was compared with AHIPSG. RESULTS: Ten subjects (30 polysomnogram tracings) were analyzed. For each backup breathing frequency (spontaneous mode, low and high backup breathing frequencies), AHI values were 62 ± 7/h, 26 ± 7/h, and 17 ± 5/h (mean ± SD), respectively. Correlation between AHINIV and AHIPSG was highly significant (r2 = 0.89, P < .001). As determined by Bland-Altman analysis, mean bias was 6.5 events/h, and limits of agreement were +26.0 and −12.9 events/h. Bias increased significantly with higher AHI values. Using a threshold AHI value of 10/h to define appropriate control of respiratory events, the ventilator software had a sensitivity of 90.9%, a specificity and positive predictive value of 100%, and a negative predictive value of 71%. CONCLUSIONS: In stable subjects with obesity-hypoventilation syndrome, the home ventilator software tested was appropriate for determining if control of respiratory events was satisfactory on NIV or if further testing or adjustment of ventilator settings was required. (ClinicalTrials.gov registration NCT01130090.)

Hot Topics in Noninvasive Ventilation: Report of a Working Group at the International Symposium on Sleep-Disordered Breathing in Leuven, Belgium

During the last few decades, attention has increasingly focused on noninvasive ventilation (NIV) in the treatment of chronic respiratory failure. The University of Leuven and the University Hospitals Leuven therefore chose this topic for a 2-day working group session during their International Symposium on Sleep-Disordered Breathing. Numerous European experts took part in this session and discussed (1) NIV in amyotrophic lateral sclerosis (when to start NIV, NIV and sleep, secretion management, and what to do when NIV fails), (2) recent insights in NIV and COPD (high-intensity NIV, NIV in addition to exercise training, and NIV during exercise training), (3) monitoring of NIV (monitoring devices, built-in ventilator software, leaks, and asynchronies) and identifying events during NIV; and (4) recent and future developments in NIV (target-volume NIV, electromyography-triggered NIV, and autoregulating algorithms).

Effects of different early rehabilitation techniques on haemodynamic and metabolic parameters in sedated patients: protocol for a randomised, single-bind, cross-over trial

Introduction Early rehabilitation has become widespread practice for patients in intensive care; however, the prevalence of intensive care unit-acquired weakness remains high and the majority of physiotherapy is carried out in bed. Several inbed rehabilitation methods exist, but we hypothesise that techniques that provoke muscle contractions are more effective than passive techniques. Methods A randomised, controlled cross-over study will be carried out to evaluate and compare the effectiveness of early rehabilitation techniques on cardiac output (CO) in sedated patients in intensive care. 20 intubated and sedated patients will undergo 4 10 min rehabilitation sessions. 2 sessions will involve ‘passive’ techniques based on mobilisations and inbed cycle ergometry and 2 involving electrostimulation of the quadriceps muscle and Functional Electrical Stimulation-cycling (FES-cycling). The primary outcome is CO measured by Doppler ultrasound. The secondary outcomes are right ventricular function, pulmonary systolic arterial pressure, muscle oxygenation and minute ventilation during exercise. Results and conclusion Approval has been granted by our Institutional Review Board (Comité de Protection des Personnes Nord-Ouest 3). The results of the trial will be presented at national and international meetings and published in peer-reviewed journals. Trial registration number NCT02920684.

Intrapulmonary Percussive Ventilation as an Airway Clearance Technique in Subjects With Chronic Obstructive Airway Diseases

BACKGROUND: Airway clearance techniques are regularly proposed as a part of the treatment in chronic obstructive airway diseases. Intrapulmonary percussive ventilation (IPV) is used as an airway clearance technique in patients affected by excessive lung secretions. The aim of this systematic review is to summarize the physiological and clinical effects related to the use of IPV as an airway clearance technique in chronic obstructive airway diseases. METHODS: This systematic review followed the PRISMA guidelines. Randomized, controlled, comparative, and cohort studies investigating IPV as an airway clearance technique were identified and reviewed from 3 databases. Two reviewers independently assessed study quality and reviewed the selected studies. RESULTS: 278 subjects from 12 studies were included in the final analysis, with 3 diseases studied. Only one of the included studies had a sample size > 50 subjects. The main findings showed that IPV improves gas exchange during exacerbation and could reduce the hospital length of stay for patients with COPD. In subjects with cystic fibrosis, neither lung function nor other parameters were improved. CONCLUSIONS: The systematic use of IPV as an airway clearance technique in chronic obstructive airway diseases is not supported by sufficiently strong evidence to recommend routine use in this patient population.