Six-month nocturnal nasal positive pressure ventilation improves respiratory muscle capacity and exercise endurance in patients with chronic hypercapnic respiratory failure

Chronic non-invasive ventilation for chronic obstructive pulmonary disease

BACKGROUND

Chronic non-invasive ventilation (NIV) is increasingly being used to treat people with COPD who have respiratory failure, but the evidence supporting this treatment has been conflicting.

OBJECTIVES

To assess the effects of chronic non-invasive ventilation at home via a facial mask in people with COPD, using a pooled analysis of IPD and meta-analysis.

SEARCH METHODS

We searched the Cochrane Airways Register of Trials, MEDLINE, Embase, PsycINFO, CINAHL, AMED, proceedings of respiratory conferences, clinical trial registries and bibliographies of relevant studies. We conducted the latest search on 21 December 2020.

SELECTION CRITERIA

We included randomised controlled trials (RCTs) comparing chronic NIV for at least five hours per night for three consecutive weeks or more (in addition to standard care) versus standard care alone, in people with COPD. Studies investigating people initiated on NIV in a stable phase and studies investigating NIV commenced after a severe COPD exacerbation were eligible, but we reported and analysed them separately. The primary outcomes were arterial blood gases, health-related quality of life (HRQL), exercise capacity (stable COPD) and admission-free survival (post-exacerbation COPD). Secondary outcomes for both populations were: lung function, COPD exacerbations and admissions, and all-cause mortality. For stable COPD, we also reported respiratory muscle strength, dyspnoea and sleep efficiency.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. After inclusion of a study, we requested the IPD. We analysed continuous and time-to-event data using linear- and cox-regression mixed-effect models with a random effect on study level. We analysed dichotomous IPD using generalised estimating equations. We adjusted all models for age and sex. We assessed changes in outcomes after three and 12 months.  We also conducted a meta-analysis on aggregated trial data.

MAIN RESULTS

We included 14 new RCTs in this review update, in addition to the seven previously included. Seventeen studies investigated chronic NIV in stable COPD and four studies investigated chronic NIV commenced after a severe COPD exacerbation. Three studies compared NIV to sham continuous positive airway pressure (2 to 4 cmH₂O). Seven studies used a nasal mask, one study used an oronasal mask and eight studies used both interfaces. Five studies did not report the interface. The majority of trials (20/21) were at high risk of performance bias due to an unblinded design. We considered 11 studies to have a low risk of selection bias and 13 to have a low risk of attrition bias. We collected and analysed the IPD from 13 stable COPD studies (n = 778, 68% of the participants included) and from three post-exacerbation studies (n = 364, 96% of the participants included). In the stable COPD group, NIV probably results in a minor benefit on the arterial partial pressure of oxygen (PaO₂) after three months (adjusted mean difference (AMD) 0.27 kPa, 95% CI 0.04 to 0.49; 9 studies, 271 participants; moderate-certainty evidence), but there was little to no benefit at 12 months (AMD 0.09 kPa, 95% CI -0.23 to 0.42; 3 studies, 171 participants; low-certainty evidence). The arterial partial pressure of carbon dioxide (PaCO₂) was reduced in participants allocated to NIV after three months (AMD -0.61 kPa, 95% CI -0.77 to -0.45; 11 studies, 475 participants; high-certainty evidence) and persisted up to 12 months (AMD -0.42 kPa, 95% CI -0.68 to -0.16; 4 studies, 232 participants; high-certainty evidence).  Exercise capacity was measured with the 6-minute walking distance (minimal clinical important difference: 26 m). There was no clinically relevant effect of NIV on exercise capacity (3 months: AMD 15.5 m, 95% CI -0.8 to 31.7; 8 studies, 330 participants; low-certainty evidence; 12 months: AMD 26.4 m, 95% CI -7.6 to 60.5; 3 studies, 134 participants; very low-certainty evidence). HRQL was measured with the Severe Respiratory Insufficiency and the St. Georges's Respiratory Questionnaire and may be improved by NIV, but only after three months (3 months: standardised mean difference (SMD) 0.39, 95% CI 0.15 to 0.62; 5 studies, 259 participants; very low-certainty evidence; 12 months: SMD 0.15, 95% CI -0.13 to 0.43; 4 studies, 200 participants; very low-certainty evidence). Lastly, the risk for all-cause mortality is likely reduced by NIV (adjusted hazard ratio (AHR) 0.75, 95% CI 0.58 to 0.97; 3 studies, 405 participants; moderate-certainty evidence). In the post-exacerbation COPD group, there was little to no benefit on the PaO₂ after three months, but there may be a slight decrease after 12 months (3 months: AMD -0.10 kPa, 95% CI -0.65 to 0.45; 3 studies, 234 participants; low-certainty evidence; 12 months: -0.27 kPa, 95% CI -0.86 to 0.32, 3 studies; 170 participants; low-certainty evidence). The PaCO₂ was reduced by NIV at both three months (AMD -0.40 kPa, 95% CI -0.70 to -0.09; 3 studies, 241 participants; moderate-certainty evidence) and 12 months (AMD -0.52 kPa, 95% CI -0.87 to -0.18; 3 studies, 175 participants; high-certainty evidence). NIV may have little to no benefit on HRQL (3 months: SMD 0.25, 95% CI -0.01 to 0.51; 2 studies, 219 participants; very low-certainty evidence; 12 months: SMD 0.25, 95% -0.06 to 0.55; 2 studies, 164 participants; very low-certainty evidence). Admission-free survival seems improved with NIV (AHR 0.71, 95% CI 0.54 to 0.94; 2 studies, 317 participants; low-certainty evidence), but the risk for all-cause mortality does not seem to improve (AHR 0.97, 95% CI 0.74 to 1.28; 2 studies, 317 participants; low-certainty evidence).

AUTHORS' CONCLUSIONS

Regardless of the timing of initiation, chronic NIV improves daytime hypercapnia. In addition, in stable COPD, survival seems to be improved and there might be a short term HRQL benefit. In people with persistent hypercapnia after a COPD exacerbation, chronic NIV might prolong admission-free survival without a beneficial effect on HRQL. In stable COPD, future RCTs comparing NIV to a control group receiving standard care might no longer be warranted, but research should focus on identifying participant characteristics that would define treatment success. Furthermore, the optimal timing for initiation of NIV after a severe COPD exacerbation is still unknown.

Six-minute walk test before and after large-volume paracentesis in cirrhotic patients with refractory ascites: A pilot study

BACKGROUND/AIMS

Functional impairment is common among cirrhotic patients with refractory ascites, and improvement in functional impairment is an expected issue after paracentesis. The six-minute walk test (6MWT) is considered an objective test for functional activity. No published data have evaluated the 6MWT among cirrhotic patients with refractory ascites before and after large-volume paracentesis. The research aim was to assess the feasibility of performing the 6MWT among cirrhotic patients who had refractory ascites before and after large-volume paracentesis.

MATERIALS AND METHODS

Thirty-one cirrhotic inpatients with refractory ascites were subjected to pulmonary function tests (forced expiratory volume in one second [FEV1], forced vital capacity [FVC], FEV1/FVC) and diffusion lung capacity for carbon monoxide (DLCO) before and 48 h after therapeutic large-volume paracentesis. Dyspnoea as assessed by the Borg scale and functional capacity as assessed by the 6MWT were also evaluated.

RESULTS

Prior to paracentesis, the mean values of FVC and FEV1 were lower than the predicted values, and a significant increase was observed after paracentesis. There was improvement in the mean DLCO values after paracentesis (P < 0.05). Regarding the 6MWT, significant increases in the walked distance (6MWD) (310.7 ± 73 vs. 348.7 ± 72.3 m) and oxygen saturation after paracentesis (P = 0.001) were observed. Significant improvement in the dyspnoea scale also occurred after paracentesis (P = 0.001). A significant positive correlation between the 6MWD before paracentesis and serum albumin levels was demonstrated (r = 0.373, P = 0.039).

CONCLUSION

We found a decrease in pulmonary function and the 6MWD in patients who had refractory ascites, which improved significantly following large-volume paracentesis. The 6MWT is useful in detecting impaired functional capacity among cirrhotic patients.

Maximum inspiratory pressure as a clinically meaningful trial endpoint for neuromuscular diseases: a comprehensive review of the literature

Respiratory muscle strength is a proven predictor of long-term outcome of neuromuscular disease (NMD), including amyotrophic lateral sclerosis, Duchenne muscular dystrophy, and spinal muscular atrophy. Maximal inspiratory pressure (MIP), a sensitive measure of respiratory muscle strength, one of several useful tests of respiratory muscle strength, is gaining interest as a therapeutic clinical trial endpoint for NMD. In this comprehensive review we investigate the use of MIP as a measure of respiratory muscle strength in clinical trials of therapeutics targeting respiratory muscle, examine the correlation of MIP with survival, quality of life, and other measures of pulmonary function, and outline the role of MIP as a clinically significantly meaningful outcome measure. Our analysis supports the utility of MIP for the early evaluation of respiratory muscle strength, especially of the diaphragm, in patients with NMD and as a surrogate endpoint in clinical trials of therapies for NMD.

Non-invasive ventilation during exercise training for people with chronic obstructive pulmonary disease

BACKGROUND

Exercise training as a component of pulmonary rehabilitation improves health-related quality of life (HRQL) and exercise capacity in people with chronic obstructive pulmonary disease (COPD). However, some individuals may have difficulty performing exercise at an adequate intensity. Non-invasive ventilation (NIV) during exercise improves exercise capacity and dyspnoea during a single exercise session. Consequently, NIV during exercise training may allow individuals to exercise at a higher intensity, which could lead to greater improvement in exercise capacity, HRQL and physical activity.

OBJECTIVES

To determine whether NIV during exercise training (as part of pulmonary rehabilitation) affects exercise capacity, HRQL and physical activity in people with COPD compared with exercise training alone or exercise training with sham NIV.

SEARCH METHODS

We searched the following databases between January 1987 and November 2013 inclusive: The Cochrane Airways Group specialised register of trials, AMED, CENTRAL, CINAHL, EMBASE, LILACS, MEDLINE, PEDro, PsycINFO and PubMed. 

SELECTION CRITERIA

Randomised controlled trials that compared NIV during exercise training versus exercise training alone or exercise training with sham NIV in people with COPD were considered for inclusion in this review.

DATA COLLECTION AND ANALYSIS

Two review authors independently selected trials for inclusion in the review, extracted data and assessed risk of bias. Primary outcomes were exercise capacity, HRQL and physical activity; secondary outcomes were training intensity, physiological changes related to exercise training, dyspnoea, dropouts, adverse events and cost.

MAIN RESULTS

Six studies involving 126 participants who completed the study protocols were included. Most studies recruited participants with severe to very severe COPD (mean forced expiratory volume in one second (FEV1) ranged from 26% to 48% predicted). There was an increase in percentage change peak and endurance exercise capacity with NIV during training (mean difference in peak exercise capacity 17%, 95% confidence interval (CI) 7% to 27%, 60 participants, low-quality evidence; mean difference in endurance exercise capacity 59%, 95% CI 4% to 114%, 48 participants, low-quality evidence). However, there was no clear evidence of a difference between interventions for all other measures of exercise capacity. The results for HRQL assessed using the St George's Respiratory Questionnaire do not rule out an effect of NIV (total score mean 2.5 points, 95% CI -2.3 to 7.2, 48 participants, moderate-quality evidence). Physical activity was not assessed in any study. There was an increase in training intensity with NIV during training of 13% (95% CI 1% to 27%, 67 participants, moderate-quality evidence), and isoload lactate was lower with NIV (mean difference -0.97 mmol/L, 95% CI -1.58mmol/L to -0.36 mmol/L, 37 participants, moderate-quality evidence). The effect of NIV on dyspnoea or the number of dropouts between interventions was uncertain, although again results were imprecise. No adverse events and no information regarding cost were reported. Only one study blinded participants, whereas three studies used blinded assessors. Adequate allocation concealment was reported in four studies.

AUTHORS' CONCLUSIONS

The small number of included studies with small numbers of participants, as well as the high risk of bias within some of the included studies, limited our ability to draw strong evidence-based conclusions. Although NIV during lower limb exercise training may allow people with COPD to exercise at a higher training intensity and to achieve a greater physiological training effect compared with exercise training alone or exercise training with sham NIV, the effect on exercise capacity is unclear. Some evidence suggests that NIV during exercise training improves the percentage change in peak and endurance exercise capacity; however, these findings are not consistent across other measures of exercise capacity. There is no clear evidence that HRQL is better or worse with NIV during training. It is currently unknown whether the demonstrated benefits of NIV during exercise training are clinically worthwhile or cost-effective.

One-year non-invasive ventilation in chronic hypercapnic COPD: effect on quality of life

The data on long-term application of non-invasive ventilation (NIV) in patients with chronic respiratory failure due to COPD are contradictory. We evaluated the effect of the addition of NIV to optimal treatment for 1 year on the quality of life of stable hypercapnic COPD patients. NIV was offered to 49 of 58 initially enrolled consecutive patients, of whom 22 refused NIV and comprised the standard treatment group whereas 27 received NIV. Quality of life was assessed with the SF-36 questionnaire. Additional measurements included blood gases, pulmonary function tests, dyspnea, daytime sleepiness, exacerbations and hospitalizations. The NIV group showed a significant improvement in quality of life in the third month, both in the Physical (31+/-4 to 38+/-8, p<0.0001) and the Mental Component Summary Score (28+/-7 to 40+/-10, p=0.009), that was maintained until the twelfth month. PaCO2 decreased by the first month in the NIV group (54+/-4.5 to 44.6+/-5.6 mmHg, p<0.0001), and PaO2 rose during the sixth month (58.9+/-5.7 to 64.4+/-6.5 mmHg, p=0.004). Dyspnea and diurnal sleepiness improved significantly. No significant improvements were observed in the control group. Patients on NIV spent less days in the hospital compared to controls. NIV when added to optimal medical treatment has beneficial effects on quality of life in stable hypercapnic COPD patients, with additional improvements in arterial blood gases, dyspnea and daytime sleepiness.

Six Minute Walk Test to assess functional capacity in chronic liver disease patients

AIM: To examine the utility of Six Minute Walk Test (6MWT) in patients with chronic liver disease (CLD).

METHODS: Two hundred and fifty subjects between the ages of 18 and 80 (mean 47) years performed 6MWT and the Six Minute Walk Distance (6MWD) was measured.

RESULTS: The subjects were categorized into four groups. Group A (n = 45) healthy subjects (control); group B (n = 49) chronic hepatitis B patients; group C (n = 54) chronic hepatitis C patients; group D (n = 98) liver cirrhosis patients. The four groups differed in terms of 6MWDs (P < 0.001). The longest distance walked was 421 ± 47 m by group A, then group B (390 ± 53 m), group C (357 ± 72 m) and group D (306 ± 111 m). The 6MWD correlated with age (r = -0.482, P < 0.01), hemoglobin (r = +0.373, P < 0.001) and albumin (r = +0.311, P < 0.001) levels. The Child-Pugh classification was negatively correlated with the 6MWD in cirrhosis (group D) patients (r = -0.328, P < 0.01). At the end of a 12 mo follow-up period, 15 of the 98 cirrhosis patients had died from disease complications. The 6MWD for the surviving cirrhotic patients was longer than for non-survivors (317 ± 101 vs 245 ± 145 m, P = 0.021; 95% CI 11-132). The 6MWD was found to be an independent predictor of survival (P = 0.024).

CONCLUSION: 6MWT is a useful tool for assessing physical function in CLD patients. We suggest that 6MWD may serve as a prognostic indicator in patients with liver cirrhosis.