Abstract
The technology underlying the development of novel ventilatory modes for long-term noninvasive ventilation of patients with chronic hypercapnia is continuously evolving. Volume-targeted pressure-controlled ventilation is a hybrid ventilation mode designed to combine the advantages of conventional ventilation modes, while avoiding their drawbacks. However, manufacturers have created different names and have patented algorithms and set-up variables, which can result in confusion for physicians and respiratory therapists. In addition, clear evidence for the superiority of this novel mode has not yet been established. These factors have most likely hindered more widespread use of this mode in clinical practice. The current review presents the rationale, working principles, characteristics and set-up recommendations associated with volume-targeted modes. In addition, it summarises the clinical and laboratory studies that have challenged this mode.
Abstract
The NIV-ventilator automatisation trend: careful titration process, ideally under sleep studies, is what matters! http://ow.ly/iXai30bNQx8
Introduction
A worldwide increase in the use of long-term noninvasive ventilation (NIV) in patients with chronic hypercapnic respiratory failure in various clinical settings has occurred over the past 30 years [1–3]. This has led to a boost in the manufacture of ventilators with continuously developing novel ventilatory modes, as well as the recruitment of new technologies aimed at better patient–ventilator synchrony [4].
In 1992, a new ventilatory mode named “volume-assured pressure-support ventilation” was introduced into the market, with the aim of combining the advantages of conventional volume- and pressure-controlled ventilation [5]. Since then, many manufacturers have developed their own patented volume-targeted systems; overall, they can be described as pressure-controlled systems that aim to ensure the average level of a predetermined tidal volume (VT) or alveolar ventilation (VʹA). This mode is, therefore, an adaptive dual-targeting mode. According to different mathematical algorithms, this means that adjustments in inspiratory pressure (first target) take place over several breaths until the ventilator delivers the target VT or VʹA (second target). Thus, the term chosen for the purpose of the current review article is “volume-targeted pressure-controlled ventilation” (VTPCV).
The adaptive characteristics of VTPCV should permit the ventilator to properly react to changes in pulmonary impedance (i.e. body position or pulmonary mechanics) and maintain effective ventilation. Hence, setting unnecessarily high fixed inspiratory pressures is presumably avoided. This explains why, although VTPCV was initially conceived for invasive mechanical ventilation [5], its principal use has been in the care of patients with chronic conditions, such as neuromuscular diseases, obesity hypoventilation syndrome (OHS) and chronic obstructive pulmonary disease (COPD), which are all conditions in which comfortable ventilation is crucial for the patient's long-term adherence to treatment. Another proposed application for VTPCV modes is to facilitate the NIV titration process, as fine inspiratory pressure adjustments are made automatically [6, 7].
Although all of these theoretical benefits sound appealing, the few randomised controlled trials performed to date have shown mixed results. Additionally, ventilator manufacturers have created different names and set-up variables, which can result in confusion for physicians and respiratory therapists. Together, these factors have likely hindered more widespread use of this ventilation mode in clinical practice.
The current review presents the rationale, working principles, characteristics and set-up recommendations pertinent to volume-targeted modes that are available for home turbine-driven ventilators. Additionally, it summarises the clinical and laboratory studies that have challenged the validity of this mode.
Rationale for volume-targeted pressure-controlled ventilation
To comprehend the rationale behind the conception of VTPCV modes, the characteristics and drawbacks of conventional ventilation modes must first be understood (table 1 and supplementary material). In addition, particular situations that can compromise ventilation efficacy will be discussed.
Principal characteristics of conventional home care ventilation and the newer dual volume-targeted pressure-controlled noninvasive ventilation modes
Volume-controlled ventilation was the main mode used for home care in the early 1990s. In this mode, the variable that needs to be set is the inspiratory flow, and hence VT (tidal volume; the integration of flow over time). Meanwhile, pressure is the dependent variable resulting from the interaction between airway resistance and overall elasticity of the respiratory system. Conversely, the independent variable to be set in the pressure-controlled mode is pressure. Therefore, the resulting VT and flow differ according to the impedance of the respiratory system.
Although the few studies that compared these two conventional ventilatory modes showed no differences in daytime blood gases or sleep quality [8, 9], pressure-controlled ventilation is by far the most extensively used NIV mode today [1] because of its relatively better leak compensation, pressure stability and patient tolerability (i.e. less gastrointestinal distension) [9, 10]. Nevertheless, a major drawback of fixed values of bi-level pressure ventilation is that they do not guarantee a minimal VT. By contrast, VTPCV modes incorporate both pressure and volume targets to ensure constant ventilation, thus seeking to combine the advantages, and avoid the drawbacks, of the two classical NIV modes.
An important consideration for effective NIV therapy is the time when it is used. NIV is mostly used during sleep to counterbalance nocturnal hypoventilation and to relieve the need for the patient to use NIV during the day. There are numerous factors that contribute to hypoventilation during the sleep state, including the variable fall in respiratory drive and the modification of respiratory impedance between sleep stages, changes in body posture and increases in upper airway resistance [11]. Therefore, one of the critical aims of NIV is to provide gentle ventilation that adapts to these changing conditions and avoids sleep fragmentation.
As shown in figure 1, it is clinically common to find patients who are sufficiently ventilated while sleeping in the lateral position, whereas in the supine position, the applied fixed inspiratory and expiratory pressures are insufficient to avoid hypoventilation and/or upper airway closure. Theoretically, the volume-targeted ventilation algorithm should react appropriately to the changing respiratory mechanics, preventing residual hypoventilation and promoting patient–ventilator synchrony.
Polysomnography in a patient with obesity hypoventilation syndrome treated with conventional noninvasive ventilation (NIV) therapy (assisted pressure-controlled ventilation mode, 33/11 cmH2O, back-up respiratory rate 16 breaths per minute, inspiratory time 1.2 s). The NIV therapy was adequate in the lateral posture (L). However, as soon as the patient turned to the supine position (S), a clear reduction in tidal volume occurred, leading to profound desaturation. No obstructive events were recognised under the measured expiratory positive airway pressure.
Working principles of volume-targeted ventilation
The aim of VTPCV modes is to automatically adjust ventilator parameters in order to guarantee a minimal tidal volume or alveolar ventilation. The machine's performance should be able to adapt to changing conditions in pulmonary mechanics as well as to unintentional leaks.
Each manufacturer has developed its own patented (and usually undisclosed) mathematical algorithm to ensure delivery of the preset VT or VʹA. This explains why, although all ventilators perform similarly, slight differences in individual ventilator responses still exist, and these may play a defining role when aiming for patient–ventilator synchrony.
The general working principles of VTPCV modes can be described as follows: the controlled variable is inspiratory pressure, which is constrained by the minimum and maximum inspiratory pressures set by the operator. Inspiration is initiated in the pressure-controlled mode, then once the machine receives feedback about the delivered volume, it “decides” whether to stay unchanged or to increase/decrease the inspiratory pressure in order to reach the dependent variable (the preset VT), before cycling on to expiration (figure 2). In the ResMed® (Sydney, Australia) ventilation systems, their mode of iVAPS (intelligent Volume-Assured Pressure Support) means there is also an increase in respiratory rate to meet the target VʹA if the patient's breathing frequency is less than two-thirds of the target respiratory rate. The cycling variable can be either time or the percentage of inspiratory flow decay (table 1). The baseline variable, expiratory positive airway pressure (EPAP), can be fixed or automatically adjusted within a range of minimum and maximum pressures set by the operator. The time span to reach the target VT/VʹA should be sufficiently rapid to avoid hypoventilation, but sufficiently smooth to avoid sleep disruption [12]. In this respect, the algorithm initially used to reach the set VT within one breath is no longer valid [5, 13]. Instead, slight and consecutive pressure support adjustments occur within several breaths, or over a minute, until the target VT is reached. The current software programs for different VTPCV modes vary significantly in terms of speed adjustment to this response (supplementary material). Moreover, although some ventilators allow the operator to set the pressure support speed adjustment, others possess a fixed response rate, and still others react depending on how much the VT is shifted from the programmed target VT value. Using the iVAPS mode as an example, if alveolar ventilation is 50% below target, the rate of increase in pressure support is 0.35 cmH2O per second. Conversely, at 200% of the ventilation target, the rate of decrease in pressure support is 0.5 cmH2O per second.
a) Pressure-support changes in a specified time or number of breaths (depending on the ventilator's algorithm) applied to reach the target tidal volume (VT). b) Impact of the ventilator pressure support (PS) adjustment on VT in response to different respiratory mechanic situations caused by changes in body position and patient effort.
In a different mode called AVAPS (average volume-assured pressure support; Philips Respironics®, Greensburg, PA, USA), the patient's tidal volume is averaged over 1 min and the inspiratory pressure increases according to the speed rate set by the operator (from ±1 up to 5 cmH2O per min). Meanwhile, the algorithm that offers the best combination of both efficient and comfortable ventilation remains unknown.
The ability of the ventilator's feedback system to accurately monitor the actual VT is crucial for proper compensation by the software. It is widely, but incorrectly, thought that VTPCV algorithms are always based on the direct measurement of expiratory VT (VTexp). This requires pneumotacographic measurement on the expiratory port of the ventilator; however, most devices do not allow the possibility of monitoring VTexp, owing to an intrinsic feature of the circuit (i.e. ventilators with a single limb that are not provided with pneumotacographic measurement proximal to the airway) [14]. To the best of our knowledge, only two commercially available turbine-driven ventilators with a double-limb circuit (the Monnal T50 and Weinmann ventilators) use VTexp as a VT target for VTPCV modes. Of note, in the presence of an expiratory leak, this method may underestimate the real VT and overcalculate the delivered volume [14].
Another alternative for monitoring expired VT is to estimate it, as in a vented intentional-leak circuit. Pressure and flow are measured inside the ventilator, taking into account the ventilator's turbine speed throughout the entire respiratory cycle, the intentional/unintentional leaks, and the detection of the beginning and end of inspiration. Subsequently, the ventilator is able to rebuild the patient's flow pattern and establish a “baseline” breathing pattern that corresponds to the patient's zero flow, to obtain an estimated VTexp equal to the inspiratory VT (VTi). As a result, some ventilators accurately estimate VTexp, even during constant leakage [15]. Special considerations about this important topic are discussed below.
How to set up a ventilator for volume-targeted pressure-controlled ventilation
A stepwise recommendation for how to set a ventilator using VT-targeted modes is shown in table 2. Please see supplementary material for a stepwise recommendation on how to set a ventilator using VʹA-targeted modes.
How to set a ventilator on tidal volume (VT)-targeted mode
Tidal volume target setting
One key variable for the effectiveness of VT-targeted modes is how to define the target VT value for each particular patient. If the set VT is too low, the patient will probably be under-treated, whereas if it is too high, ventilation could become uncomfortable for the patient. It is also important to bear in mind that, although the set VT will probably be reached, additional patient effort that contributes to pressure-supported breathing may lead to the set volume being exceeded.
Despite the number of considerations in place, the amount (millilitres) of VT that needs to be calculated per kilogram of (patient) weight has still not been standardised. Previous clinical trials have used various approaches (table 3), rendering these trials incomparable and introducing a bias that may in part explain their inconsistent results. Regarding the patient's weight, the ideal body weight (IBW) is normally used in preference to actual body weight (ABW) to calculate VT, otherwise there are concerns that the ABW in obese or underweight patients could lead to an excessive or insufficient VT, respectively. Nevertheless, there is no universally accepted formula for calculating IBW. Moreover, comparison of three IBW formulas showed significant differences between them, both for men and for women [16].
Clinical studies performed with volume-targeted pressure-controlled ventilation (VTPCV) mode for home mechanical ventilation (HMV)
Finally, to add even more confusion, the ventilator manufacturers recommend different rather than evidence-based formulas to define the target VT. A further point to be considered is the patient's underlying pathology. An analysis of downloaded data from 150 home ventilators used by stable patients showed variability of VT and minute volume values (possibly reflecting the different requirements) depending on the cause of the ventilatory failure [17]. In conclusion, the current heterogeneous calculation of VT underscores the need for a consensus between clinicians, investigators and manufacturers to establish a standardised calculation for IBW and the target VT value (in mL/kg) for every pathology.
An alternative approach to define VT and minute volume settings is to use the autotitration function offered by VʹA-targeted mode (iVAPS) ventilators. Firstly, the ventilator estimates the baseline VʹA following a 20-min learning period during spontaneous breathing under 4 cm H2O when the patient is awake. Based on the patient's learned parameters, the software automatically defines the ventilator's settings to meet the determined target ventilation. However, applying a hypercapnic patient's daytime-learned VʹA might be insufficient to overcome respiratory insufficiency [6, 7]. It is also important to note that previous work has shown that a greater number of operator adjustments in the autotitrating ventilator were needed to optimise ventilation compared with conventional ventilation treatment [7].
Manufacturers pledge that VTPCV modes could simplify the titration process, therefore being helpful in limited manpower settings. Nevertheless, it is important to bear in mind that more parameters need to be set and interpreted during VTPCV compared with conventional modes. Therefore, it is advisable to have a more highly trained team to handle these more complex hybrid modes and ensure their proper use.
Pressure support window setting
The ventilator either increases or decreases the level of pressure support, with the aim of achieving the set VT. Thus, minimal and maximal inspiratory positive airway pressure (IPAP) must be set to provide a pressure window that should be wide enough to let the algorithm work within proper limits. In this respect, the minimum pressure support setting should correspond to a safe level of VT for the patient. Likewise, the maximum pressure support setting enables the ventilator to increase inspiratory pressures and compensate for drops in VT in cases of leakage or reduced inspiratory effort (i.e. while sleeping) [14, 16]. Additionally, if the IPAP minimum is too high, the set VT will be exceeded, whereas if the IPAP maximum is set too low, the set VT will not be reached.
A pragmatic approach is to set a wide range for the pressure support window initially, and subsequently carry out pressure reductions according to clinical observations, ventilator software data and usual monitoring parameters (blood gases, sleep studies including oximetry/transcutaneous carbon dioxide tension).
EPAP pressure setting
As mentioned above, the EPAP level can be a fixed value adjusted in response to clinical observations or following measurements during polygraphy or polysomnography. Alternatively, some ventilators (e.g. AVAPS-AE, Philips®; iVAPS-autoEPAP, ResMed®; PRISMA 30 ST, Löwenstein Medical, Weinmann®) also allow the EPAP level to be automatically adjusted to maintain upper airway patency between constrained minimum and maximum pressures set by the operator. For this purpose, most new devices use snore detection in combination with flow detection. Apnoea and hypopnoea are typically defined as a reduction in ventilation below a percentage of recent breathing for at least 10 s, with varying methods of flow analysis. The distinction between central or obstructive events includes cardiogenic pulsation testing and device-generated pressure oscillations [18]. Although these methods probably provide a good approach against upper airway obstruction, there are still concerns about their accuracy [19]. Caution is advised until specific studies evaluating the automated EPAP function are published [20].
Pitfalls of volume-targeted pressure-controlled ventilation modes
Response to leaks
Leaks are divided into “intentional” (occur by default from the mask exhalation port in vented circuit configuration) and “unintentional” (occur between the skin and the mask, or in the case of nasal mask usage, via the opened mouth) [21]. Unintentional leaks are almost unavoidable during NIV, and can hinder its success, leading to patient–ventilator asynchrony, sleep disturbance and hypoventilation [22–25].
Therefore, ventilators and their individual modes should have the capacity to cope with unintentional (and variable) leaks. This depends on the accuracy of the leak calculation, the circuit configuration and the corresponding output of the system. Intentional and unintentional leaks in vented circuit configuration are computed over the entire respiratory cycle. Unintentional leaks are not considered to be part of the delivered VT; therefore, the delivered VT should remain constant in the presence of a linear (not random) unintentional leak. In the unvented circuit configuration (circuit provided with inspiratory/expiratory valves), VTi values are computed at the beginning of inspiration, so that in the presence of an unintentional leak, the delivered VT will be overestimated. In other words, the increased flow generated by the leak is included in the integral of overall flow used to calculate VTi. This means that the higher the leak, the higher the considered VTi.
In a study evaluating the built-in software of seven home ventilators in vented configuration, Contal et al. [26] showed that in the presence of leaks, VT was underestimated by all the devices, and the bias (range 66–236 mL) increased with higher insufflation pressures.
Presented with this difficulty, several laboratory studies have investigated the capability of home ventilators using the VTPCV mode to maintain the preset VT under different conditions. Carlucci et al. [25] showed that, regardless of the circuit configuration, these ventilators were able to maintain the set VT in the absence of leaks in normal, obstructive and restrictive lung modes. They coped acceptably well with moderate to high leaks, albeit only when used in conjunction with a vented circuit configuration. Conversely, all devices in nonvented circuit configurations undercompensated for VT in the presence of leaks. A further study by Khirani et al. [14] resulted in similar findings. Indeed, all ventilators failed to guarantee the set VT in the presence of leaks when used with a “true” expiratory valve.
The effectiveness of the double-limb circuit was also tested. Surprisingly, two of the devices did not measure expiratory VT, and were thus unable to compensate for unintentional leaks. Another ventilator with a double-limb circuit overcompensated for VT because it equated expiratory VT with its target VT. This excessive delivery of VT was due to the presence of expiratory leaks that led to the underestimation of the real VTi. Luján et al. [16] found that five tested ventilators in “vented” configuration underestimated real VT (range from −21.7 to −83.5 mL). Indeed, increasing leakage was the main factor that influenced VT (range from −2.27% to −5.42% for each 10 L·min−1 leak flow increase). In addition, the same group found in two further studies that the introduction of random unintentional (especially inspiratory) leaks affected the performance of commercial ventilators with vented single-limb circuits at a magnitude that could have important clinical implications [27, 28].
Overshooting
Defined as an inadequate increase in VT of >20%, overshooting can occur in some ventilators after the removal of an unintentional leakage [25, 29]. Overshooting reflects the inability of the ventilator to rapidly respond to sudden respiratory changes and adequately decrease airway pressure, and can lead to patient–ventilator asynchrony and sleep discomfort [14, 30]. Moreover, in cases of prompt amelioration of respiratory mechanics, or following the removal of an unintentional leak, VT-targeting NIV modes may cause overshooting and hyperventilation because both respiratory rate and alveolar ventilation are not controlled. This could lead to unfavourable conditions such as lower arterial carbon dioxide tension (PaCO2) levels, which, in turn, could decrease the patient's respiratory effort and cause patient–ventilator asynchrony, periodic breathing, oxygen desaturation and microarousals [29, 31, 32]. In addition, an increase in dynamic hyperinflation could arise in patients with obstructive disease. Another concern is potential gastric air intake, which can lead to discomfort, vomiting and aspiration [29].
Role of volume-targeted pressure-controlled ventilation in clinical practice
Obesity hypoventilation syndrome
Published randomised control trials have shown that the majority of patients with OHS can be treated successfully with CPAP therapy [33–35]. However, it is recommended that bi-level positive-pressure ventilation is applied in more complex cases such as severe obesity, concomitant moderate–severe COPD and sleep-related hypoventilation with low apnoea–hypopnoea index (lone OHS), and when high initial PaCO2 levels exist or there is a need for high CPAP pressures [36, 37].
Only a few trials have compared fixed bi-level versus VTPCV NIV modes in patients with OHS [30, 38, 39]. Murphy et al. [38] performed a randomised controlled trial in 46 newly diagnosed patients with OHS with body mass index 50±7 kg·m−2, comparing VT-targeted versus fixed bi-level NIV. At 3 months, both groups showed significant improvement in gas exchange, daytime somnolence and quality of life, and no clinically important differences between the groups were found. Importantly, this trial used a strict NIV titration protocol guided by polygraphy and transcutaneous CO2 measurements to warrant optimal settings in both groups [38]. Simply put, the key messages to be retrieved from this study are: 1) both conventional and VT-targeted modes can successfully treat patients with OHS; 2) a careful and individualised titration process to deliver appropriate pressures and VT plays a deciding role in achieving the potential optimal therapy benefits, independent of the chosen mode [38, 40]; 3) controlled ventilation for more than 50% of the night led to a greater decrease in diurnal and nocturnal CO2, and improved health-related quality of life, irrespective of the mode used.
Of note, no trials have compared the long-term effects of the different positive-pressure modes on cardiovascular comorbidity, quality of life or mortality [36].
COPD
NIV use for at least 5 h per day is a known factor for determining improvement in gas exchange [41] and survival in patients with chronic hypercapnic COPD [2]. As NIV is preferably applied during the night, it makes sense to establish which mode is most comfortable for the patient. Moreover, patients with COPD can present a broad range of sleep-related disturbances, which include poor sleep quality and sleep disordered breathing [42].
In a crossover trial in ventilator-experienced patients with COPD, the impact on sleep quality of a VʹA-targeted mode versus standard fixed bi-level NIV was compared. Polysomnographic measurements for each mode had similar outcomes. However, during the 6-week period of home ventilation, there was a slightly subjective improvement in restfulness with the VʹA-targeted mode [43].
Regarding other important outcomes, the few published studies have failed to show any additional advantage of VTPCV modes over standard fixed bi-level pressure support ventilation [43–47]. Of note, the optimal method for defining the target VT value in COPD remains unknown. Oscroft et al. randomised 40 patients with COPD to VT-targeted or fixed bi-level pressure-support ventilation (PSV) treatment, with NIV titration performed during the daytime by an experienced team of nurses. After 3 months, no significant differences between groups were found in gas exchange, quality of life or compliance. In this study, the mean IPAP pressure in the fixed PSV group was 28 (27.3–30) cmH2O versus the permitted IPAP maximum of 25 cmH2O in the VT-targeted group. This could explain why a shorter titration process was required in the VT-targeted mode (3.3 versus 5.2 days) [44].
Neuromuscular disease
Overall, neuromuscular diseases account for around 10–51% of the indications for home mechanical ventilation [3, 48, 49]. The aims for initiating NIV in these patients are to prolong survival, ameliorate symptoms, decrease hospitalisation rate and improve quality of life [50]. However, there is still discussion between experts as to which mode is preferable. In addition, there are special considerations to be taken into account for neuromuscular diseases. These patients might be particularly sensitive to NIV and normally, there is a progressive course of the disease including diaphragmatic weakness and increase in NIV requirement (to 24 h per day). The decrease in muscular effort makes these patients especially prone to desaturations and hypoventilation in cases of important pressure variations [13, 51]. This may lead to glottis closure in patients with amyotrophic lateral sclerosis (ALS) [52], for example.
Although the VTPCV modes are especially recommended by the manufacturers for the group of neuromuscular diseases, their application in daily practice still appears to be limited. According to a registry in Belgium and France, out of 209 patients with neuromuscular disease, 122 (59%) were using a volume-controlled mode, while 82 (39%) were using a pressure-controlled mode and only five (2%) were using a VTPCV mode [53].
None of the few available randomised trials in neuromuscular diseases has compared long-term VTPCV modes with conventional bi-level NIV [54]. Regarding conventional modes, in a retrospective study of 144 ventilated patients with ALS, survival was similar whether volume- or pressure-preset ventilation was applied, but volume-preset NIV achieved better gas exchange and symptom relief [51].
Beyond the NIV mode chosen, probably the most important step to achieve ventilation goals is meticulous titration and optimisation of NIV parameters, ideally assessed using sleep studies [52, 55]. Vrijsen et al. [56] performed meticulous titration (using fixed bi-level PSV) during 3 nights of polysomnography in patients with ALS. On the final night of titration, and following 1 month of home mechanical ventilation, there was a significant improvement in sleep quality, carbon dioxide and nocturnal oxygen. By contrast, in a study in which titration (using a VʹA-targeted mode) was performed during daytime, guided only by patient comfort, no improvement in sleep efficiency, sleep arousals or sleep architecture was seen [57]. These unmet aims are probably not due to the use of a particular ventilatory mode, but rather due to the lack of an optimal titration process that led to insufficient ventilatory settings.
Conclusions and future considerations
Volume-targeted pressure controlled ventilation is a hybrid ventilation mode that aims to combine the advantages of conventional ventilatory modes. Unfortunately, robust evidence is not yet available to show its superiority over the traditional set-point targeting ventilators. However, clinical experience as well as scientific evidence suggest that individual patients might benefit from these adaptive modes, even though a general beneficial effect remains to be established. This must certainly be balanced against the pitfalls and complications associated with VTPC modes. Therefore, VTPC mode should cautiously be considered as an alternative mode for treating chronic respiratory insufficiency, for example in cases of residual hypoventilation under conventional modes. Hereby, taking into account that proper parameter settings are crucial for ventilation effectiveness. Therefore, ventilator's parameters should ideally be assessed under polygraphic/polysomonagraphic measurements. Probably the most important factor to provide an effective tailored NIV therapy to each patient is to manage several ventilator platforms and to understand the working principles of each device. In regards to the trend of ventilator's automatization, manufactures, clinicians and patients should work as a team towards translating artificial intelligence into tangible advances in patient care.
Supplementary material
Supplementary Material
Please note: supplementary material is not edited by the Editorial Office, and is uploaded as it has been supplied by the author.
Table S1. Principal characteristics of conventional home care ventilation and the newer dual VAP-NIV modes. ERJ-02193-2016_Table_S1
Table S2. Pressure support speed adjustment in the different home ventilators. ERJ-02193-2016_Table_S2
Table S3. How to set a ventilator in a Va assured pressure controlled mode (iVAPS). ERJ-02193-2016_Table_S3
Disclosures
Supplementary Material
M.P. Arellano-Maric ERJ-02193-2016_Arellano-Maric
M. Duivermann ERJ-02193-2016_Duivermann
C. Gregoretti ERJ-02193-2016_Gregoretti
W. Windisch ERJ-02193-2016_Windisch
Footnotes
This article has been amended according to the correction published in the July 2017 issue of the European Respiratory Journal.
This article has supplementary material available from erj.ersjournals.com
Conflict of interest: Disclosures can be found alongside this article at erj.ersjournals.com
- Received November 7, 2016.
- Accepted March 17, 2017.
- Copyright ©ERS 2017