Non-invasive ventilation effectiveness and the effect of ventilatory mode on survival in ALS patients

Abstract

Non-invasive ventilation (NIV) prolongs survival in amyotrophic lateral sclerosis (ALS), but there are no data with which to compare the effectiveness of the different ventilator modes - volume (Vol-NIV) or pressure-cycled (Pres-NIV) ventilation - in ALS. We aimed to determine whether the ventilatory mode has an effect on ventilation effectiveness and survival of ALS patients using NIV. We used a retrospective study that included all ALS patients for whom NIV was indicated in two referral units: one using Vol-NIV and the other using Pres-NIV. Demographic, functional and nocturnal gas exchange parameters at NIV initiation were recorded. Eighty-two ALS patients ventilated using Pres-NIV and 62 using Vol-NIV were included. No differences were found in survival from NIV initiation between Vol-NIV (median 15.00 (7.48-22.41) months) and Pres-NIV (median 15.00 (10.25-19.75) months, p = 0.533) patients. Effective NIV was achieved in 72.41% Vol-NIV patients and in 48.78% Pres-NIV patients (p < 0.001). Ventilator mode (OR 12.066 (4.251-32.270), p < 0.001) and severity of bulbar dysfunction (OR 1.07 (1.011-1.133), p = 0.02) were the variables correlated with effective NIV. In conclusion, although Vol-NIV provides more effective ventilation, Vol-NIV and Pres-NIV present similar survival in ALS. Effectiveness of NIV is related to the severity of bulbar dysfunction.

Tolerance of Volume Control Noninvasive Ventilation in Subjects With Amyotrophic Lateral Sclerosis

“…Moreover, we found that VC-CMV NIV was more effective in relieving symptoms of hypoventilation and was associated with less frequent changes to ventilator parameters over time. 8 This study shows that NIV tolerance was associated with time spent with S pO 2 Ͻ 90% at night while on NIV. Although differences between tolerant and intolerant subjects were not found in the percentage of subjects in whom effective NIV (as defined in methods section) was achieved, for those subjects with low NIV adherence, no improvement in P aO 2 and P aCO 2 was found, and they presented lower P aO 2 after NIV and worse minimum nocturnal S pO 2 and mean nocturnal S pO 2 while using NIV compared with tolerant subjects.…”

“…4 Our results confirm, in accordance with previous studies, that tolerant subjects use NIV for a longer period before death/tracheostomy (median 22.0 months) compared with intolerant NIV ϭ noninvasive ventilation ALS ϭ amyotrophic lateral sclerosis OR ϭ odds ratio BMI ϭ body mass index ALSFRS-R ϭ revised Amyotrophic Lateral Sclerosis Functional Rating Scale P Imax ϭ maximum inspiratory pressure P Emax ϭ maximum expiratory pressure subjects (median 6.0 months). In a recent collaboration, 8 we showed that both ventilator modes provided similar results for survival in subjects with ALS, but VC-CMV NIV seemed to provide more effective ventilation, with less time spent with S pO 2 Ͻ 90% at night and higher minimum nocturnal S pO 2 and mean S pO 2 while on NIV. If our results are compared with those from another study using PC-CMV NIV, 6 the nocturnal oxygenation of our tolerant group is largely greater.…”

“…The mean set tidal volume used in the present study is in the range of those described in previous studies, and no adverse effects have been reported. 1,8,21 Survival of subjects with ALS has been shown to be strongly associated with NIV adherence, 3,22 and NIV adherence is a predictor of the improvement produced by NIV in quality of life in subjects with ALS. 4 Our results confirm, in accordance with previous studies, that tolerant subjects use NIV for a longer period before death/tracheostomy (median 22.0 months) compared with intolerant NIV ϭ noninvasive ventilation ALS ϭ amyotrophic lateral sclerosis OR ϭ odds ratio BMI ϭ body mass index ALSFRS-R ϭ revised Amyotrophic Lateral Sclerosis Functional Rating Scale P Imax ϭ maximum inspiratory pressure P Emax ϭ maximum expiratory pressure subjects (median 6.0 months).…”

“…We have previously studied various aspects of this procedure, 29 and we have compared our results with those of a group with expertise in PC-CMV who take a similar approach to ours with regard to respiratory secretion management. 8 From an ethical standpoint, the procedure we use with our patients must be the one in which we have the most expertise; therefore, we acknowledge possible limitations in our method, most notably the lack of a control group. Taking an honest and realistic view, most of our subjects would not have understood why we were presenting them with a situation in which randomization would have been required: that the treatment they were to receive would be decided by chance, rather than one proposed by their doctor as the best option for them.…”

“…7 However, it has recently been shown that, despite no differences in survival, VC-CMV NIV provides more effective ventilation than PC-CMV NIV in subjects with ALS, improving hypoventilation symptoms in a greater proportion of subjects with fewer nocturnal desaturations. 8 The aim of this study was to determine the tolerance of subjects with ALS to VC-CMV NIV and whether a clinical or functional parameter can predict NIV tolerance in subjects with ALS treated with VC-CMV NIV.…”