Efficacy and compliance with noninvasive positive pressure ventilation in patients with chronic respiratory failure

Effect of High-Flow Nasal Oxygenation on Gastric Insufflation in Patients Undergoing Laryngeal Microsurgery under Tubeless General Anesthesia with Neuromuscular Blockade

BACKGROUND

High-flow nasal oxygenation is an oxygen delivery method by which high concentrations of heated humidified oxygen are supplied via the nasal cavity. This study aimed to investigate the effect of high-flow nasal oxygenation on gastric volume change in adult patients undergoing laryngeal microsurgery under tubeless general anesthesia with neuromuscular blockade.

METHODS

Patients aged 19-80 years with an American Society of Anesthesiologists physical status 1 or 2 who were scheduled to undergo laryngoscopic surgery under general anesthesia were recruited. Patients received high-flow nasal oxygenation therapy at 70 L/min during surgery under general anesthesia with neuromuscular blockade. The cross-sectional area of the gastric antrum was measured via ultrasound in the right lateral position before and after high-flow nasal oxygenation, and the gastric volume was calculated. The duration of apnea, i.e., the duration of administration of high-flow nasal oxygenation in the paralyzed state, was also recorded.

RESULTS

Of the 45 patients enrolled, 44 completed the study. There were no significant differences in the antral cross-sectional area in the right lateral position, gastric volume, and gastric volume per kg between before and after high-flow nasal oxygenation application. The median duration of apnea was 15 (interquartile range, 14-22) min.

CONCLUSION

High-flow nasal oxygenation at 70 L/min during apnea with the mouth open did not influence the gastric volume in patients undergoing laryngeal microsurgery under tubeless general anesthesia with neuromuscular blockade.

Optimal NIV Medicare Access Promotion: Patients With COPD: A Technical Expert Panel Report From the American College of Chest Physicians, the American Association for Respiratory Care, the American Academy of Sleep Medicine, and the American Thoracic Society

This document summarizes the work of the COPD Technical Expert Panel working group. For patients with COPD, the most pressing current coverage barriers identified were onerous diagnostic requirements focused on oxygenation (rather than ventilation) and difficulty obtaining bilevel devices with backup rate capabilities. Because of these difficulties, many patients with COPD were instead sometimes prescribed home mechanical ventilators. Critical evidence supports changes to current policies, including randomized controlled trial evidence suggesting a mortality benefit from bilevel positive airway pressure with backup rate and updated clinical practice guidelines from the American Thoracic Society as well as the European Respiratory Society. To achieve optimal access to noninvasive ventilation for patients with COPD, we make the following key recommendations: (1) removal of the need for overnight oximetry testing; (2) the ability to initiate therapy using bilevel devices with backup rate capability; and (3) increased duration of time to meet adherence criteria (ie, a second 90-day trial period) in those patients actively engaged in their care. Clear guidelines based on medical necessity are also included for patients who require initiation of or switch to a home mechanical ventilator. Adoption of these proposed recommendations would result in the right device, for the right type of patient with COPD, at the right time. Finally, we emphasize the need for adequate clinical support during initiation and maintenance of home noninvasive ventilation in such patients.

Relationship between Eating and Digestive Symptoms and Respiratory Function in Advanced Duchenne Muscular Dystrophy Patients

Background:

Duchenne muscular dystrophy (DMD) patients can have various issues that affect their quality of life, including eating and digestive conditions.

Objective:

We sought to identify the relationship between respiratory function and various eating and digestion related symptoms in patients with advanced Duchenne muscular dystrophy (DMD).

Methods:

Eating and digestive symptoms, including loss of appetite, nausea, vomiting, diarrhea, constipation, swallowing difficulty, mastication difficulty, early satiety, and aspiration, were evaluated among patients with advanced DMD who were nonambulatory and required noninvasive mechanical ventilatory support. In addition, various respiratory function parameters were measured, including forced vital capacity (FVC), maximal insufflation capacity (MIC), peak cough flow (PCF), assisted PCF (APCF), maximal inspiratory pressure (MIP), and maximal expiratory pressure (MEP). We then analyzed the relationship between gastrointestinal symptoms and respiratory function parameters.

Results:

A total of 180 patients (age, 22.3±5.0 years) were included in the analysis. Loss of appetite and early satiety showed no correlation with any of the respiratory function parameters. Constipation was correlated with MEP; swallowing difficulty was correlated with MIC, APCF, MIP and MEP; and mastication difficulty was correlated with FVC, PCF, APCF, MIP, and MEP. Notably, age did not correlate with any gastrointestinal symptoms.

Conclusions:

Eating and digestive symptoms are more closely correlated with respiratory function than with age in patients with DMD. We think this correlation is mainly caused by the skeletal muscle strength, which is major determinant of both digestive and respiratory function.

Effect of continuous positive airway pressure on gastroesophageal reflux in patients with obstructive sleep apnea: a meta-analysis

PURPOSE

Gastroesophageal reflux disease (GERD) often occurs in patients with obstructive sleep apnea (OSA). Although continuous positive airway pressure (CPAP) is considered to be the preferred treatment for OSA, the effect of CPAP therapy on reflux events remains controversial. In this study, we utilized meta-analysis to investigate whether or not CPAP treatment reduces the incidence of reflux.

METHODS

Two independent reviewers obtained the data sources from the database of PubMed, Elsevier, Cochrane library, and CNKI using search terms, and then filtered the target articles based on the inclusion and exclusion criteria. RevMan (version 5.3) and STATA (version 12.0) were used for data synthesis. The effect of CPAP treatment on GERD was studied by calculating the weighted mean difference (WMD) and standard deviation (SD) before and after CPAP treatment.

RESULTS

Ten studies involving a total of 272 participants were included in this study. The results showed that the total of WMD before and after CPAP was - 17.68 (95% CI - 30.67 to - 4.69) for percentage time pH < 4, - 24.66 (95% CI - 36.15 to - 13.18) for the longest reflux duration, - 27.53 (95% CI - 49.53 to - 5.52) for number of reflux events, - 49.76 (95% CI - 60.18 to - 39.35) for DeMeester score, - 1.85 (95% CI - 3.00 to - 0.71) for reflux diseases questionnaire (RDQ) score, and - 8.95 (95% CI - 16.00 to - 1.89) for reflux symptom index (RSI). The subgroup analysis demonstrated that the improvement of reflux symptoms was more obvious with the extension of treatment time.

CONCLUSIONS

This meta-analysis showed that CPAP treatment significantly reduces the incidence of reflux events in patients with OSA.

Home mechanical ventilation: back to basics

Over recent decades, the use of home mechanical ventilation (HMV) has steadily increased worldwide, with varying prevalence in different countries. The key indication for HMV is chronic respiratory failure with alveolar hypoventilation (e.g., neuromuscular and chest wall disease, obstructive airway diseases, and obesity-related respiratory failure). Most modern home ventilators are pressure-targeted and have sophisticated modes, alarms, and graphics, thereby facilitating optimization of the ventilator settings. However, different ventilators have different algorithms for tidal volume estimation and leak compensation, and there are also several different circuit configurations. Hence, a basic understanding of the fundamentals of HMV is of paramount importance to healthcare workers taking care of patients with HMV. When choosing a home ventilator, they should take into account many factors, including the current condition and prognosis of the primary disease, the patient’s daily performance status, time (hr/day) needed for ventilator support, family support, and financial costs. In this review, to help readers understand the basic concepts of HMV use, we describe the indications for HMV and the factors that influence successful delivery, including interface, circuits, ventilator accessories, and the ventilator itself.

Clinical Evidence of Nasal High-Flow Therapy in Chronic Obstructive Pulmonary Disease Patients

Nasal high-flow therapy (NHFT) is an upcoming treatment for chronic obstructive pulmonary disease (COPD) patients. It supplies heated, humidified, and, desirably, oxygen-enriched air through a nasal cannula at flow rates up to 60 L/min. Several studies examined the effect of NHFT in COPD patients, but a clear overview is lacking. The present review aimed to give an overview of the clinical evidence of NHFT in 3 aspects of COPD care: long-term use in stable COPD patients, use for treatment of COPD exacerbations, and use during exercise therapy in COPD. For each topic, a specific literature search was performed up to December 9, 2019. Studies show promising results, with most evidence for its long-term use in hypoxemic COPD patients that frequently exacerbate, and very limited evidence for its use during COPD exacerbations or as a worthwhile adjunct to exercise training. More evidence is therefore needed to know how to incorporate NHFT in standard clinical practice.

Beneficial effect of nocturnal oximetric control on the clinical and gasometric situation and the prognosis of patients with home non-invasive mechanical ventilation

INTRODUCTION AND OBJECTIVE

The effectiveness of home non-invasive mechanical ventilation (NIMV) is assessed by determining blood gas values in wakefulness, the evolution of their symptoms, and the monitoring of ventilation at night. The aim of our study is to evaluate whether defined values reached with outpatient monitoring by oximetry is related to the clinical, arterial gases and survival of a sample of patients with home NIMV.

MATERIAL AND METHOD

Retrospective observational cohort study of a series of patients receiving home NIMV treatment for different causes. Patients with amyotrophic lateral sclerosis and less than 3 months of follow-up were excluded. The evolution of the patient's symptoms, their baseline arterial blood gases in wakefulness, and home nocturnal oximetry records, are evaluated at each outpatient visit. Good maintained oximetry control (MOC) was defined when mean O2 saturation values were reached and maintained until the last revision. Patient groups were considered, according to whether or not a good MOC was achieved during follow-up.

RESULT

Four hundred patients were evaluated. Three hundred and sixty four (91%) were included in the study; their median age was 68 years, 51% were male. 37.6% had a good MOC during follow-up. Compared to patients with not good MOC, a better long-term mortality was obtained (16.8% vs 28.2%, P=.013), and an improvement in symptoms (33.8% vs 18.6%, P=.002) and a lower proportion of patients with persistently>50mmHg PaCO2 (14.2% vs. 33.9%, P<.001) was observed.

CONCLUSION

In the follow-up of patients with home NIMV in our context, values defined in home nocturnal oximetry (good MOC) are positively associated with clinical, gasometric and longer-term survival.

Does Adherence to Domiciliary NIMV Decrease the Subsequent Hospitalizations Rates and Cost for Patients Diagnosed with COPD?

Domiciliary noninvasive mechanical ventilation (NIMV) is used for treating patients with hypercapnic chronic obstructive pulmonary disease (COPD). We aimed to evaluate the association between adherence to the treatment and subsequent hospitalizations and costs. Data from 54 (27 adherent; 27 non-adherent) patients with COPD who were undergoing NIMV treatment at home for 6 months. We assessed adherence based on digitally recorded data and checked hospital records for clinical and laboratory data, rehospitalization rates, and costs during the following 6 months. Nocturnal NIMV usage, mean daily usage of the device, and time to first hospitalization were higher in the treatment-adherent group (p < .001, p < .001, and p=.006, respectively). The percentage of active smokers, device leaks above 30 L/min, length of hospital stay, rehospitalization rates, and costs were significantly higher in the treatment-non-adherent group (p = 05, p = 006, p = 004, p = 006, and p = 01, respectively). The most frequent reasons for not using NIMV in the treatment-non-adherent group were a decreased need, dry mouth, mask incompatibility, and gastrointestinal complaints. Adherence to NIMV treatment decreases the subsequent hospitalizations rates and noncompliance leads to complications. Findings of this study may help physicians in convincing patients diagnosed with COPD of the need for correct NIMV use to prevent hospitalizations and reduce the costs of COPD treatment.

Non-invasive ventilation for the management of acute hypercapnic respiratory failure due to exacerbation of chronic obstructive pulmonary disease

BACKGROUND

Non-invasive ventilation (NIV) with bi-level positive airway pressure (BiPAP) is commonly used to treat patients admitted to hospital with acute hypercapnic respiratory failure (AHRF) secondary to an acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

OBJECTIVES

To compare the efficacy of NIV applied in conjunction with usual care versus usual care involving no mechanical ventilation alone in adults with AHRF due to AECOPD. The aim of this review is to update the evidence base with the goals of supporting clinical practice and providing recommendations for future evaluation and research.

SEARCH METHODS

We identified trials from the Cochrane Airways Group Specialised Register of trials (CAGR), which is derived from systematic searches of bibliographic databases including the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), the Allied and Complementary Medicine Database (AMED), and PsycINFO, and through handsearching of respiratory journals and meeting abstracts. This update to the original review incorporates the results of database searches up to January 2017.

SELECTION CRITERIA

All randomised controlled trials that compared usual care plus NIV (BiPAP) versus usual care alone in an acute hospital setting for patients with AECOPD due to AHRF were eligible for inclusion. AHRF was defined by a mean admission pH < 7.35 and mean partial pressure of carbon dioxide (PaCO2) > 45 mmHg (6 kPa). Primary review outcomes were mortality during hospital admission and need for endotracheal intubation. Secondary outcomes included hospital length of stay, treatment intolerance, complications, changes in symptoms, and changes in arterial blood gases.

DATA COLLECTION AND ANALYSIS

Two review authors independently applied the selection criteria to determine study eligibility, performed data extraction, and determined risk of bias in accordance with Cochrane guidelines. Review authors undertook meta-analysis for data that were both clinically and statistically homogenous, and analysed data as both one overall pooled sample and according to two predefined subgroups related to exacerbation severity (admission pH between 7.35 and 7.30 vs below 7.30) and NIV treatment setting (intensive care unit-based vs ward-based). We reported results for mortality, need for endotracheal intubation, and hospital length of stay in a 'Summary of findings' table and rated their quality in accordance with GRADE criteria.

MAIN RESULTS

We included in the review 17 randomised controlled trials involving 1264 participants. Available data indicate that mean age at recruitment was 66.8 years (range 57.7 to 70.5 years) and that most participants (65%) were male. Most studies (12/17) were at risk of performance bias, and for most (14/17), the risk of detection bias was uncertain. These risks may have affected subjective patient-reported outcome measures (e.g. dyspnoea) and secondary review outcomes, respectively.Use of NIV decreased the risk of mortality by 46% (risk ratio (RR) 0.54, 95% confidence interval (CI) 0.38 to 0.76; N = 12 studies; number needed to treat for an additional beneficial outcome (NNTB) 12, 95% CI 9 to 23) and decreased the risk of needing endotracheal intubation by 65% (RR 0.36, 95% CI 0.28 to 0.46; N = 17 studies; NNTB 5, 95% CI 5 to 6). We graded both outcomes as 'moderate' quality owing to uncertainty regarding risk of bias for several studies. Inspection of the funnel plot related to need for endotracheal intubation raised the possibility of some publication bias pertaining to this outcome. NIV use was also associated with reduced length of hospital stay (mean difference (MD) -3.39 days, 95% CI -5.93 to -0.85; N = 10 studies), reduced incidence of complications (unrelated to NIV) (RR 0.26, 95% CI 0.13 to 0.53; N = 2 studies), and improvement in pH (MD 0.05, 95% CI 0.02 to 0.07; N = 8 studies) and in partial pressure of oxygen (PaO2) (MD 7.47 mmHg, 95% CI 0.78 to 14.16 mmHg; N = 8 studies) at one hour. A trend towards improvement in PaCO2 was observed, but this finding was not statistically significant (MD -4.62 mmHg, 95% CI -11.05 to 1.80 mmHg; N = 8 studies). Post hoc analysis revealed that this lack of benefit was due to the fact that data from two studies at high risk of bias showed baseline imbalance for this outcome (worse in the NIV group than in the usual care group). Sensitivity analysis revealed that exclusion of these two studies resulted in a statistically significant positive effect of NIV on PaCO2. Treatment intolerance was significantly greater in the NIV group than in the usual care group (risk difference (RD) 0.11, 95% CI 0.04 to 0.17; N = 6 studies). Results of analysis showed a non-significant trend towards reduction in dyspnoea with NIV compared with usual care (standardised mean difference (SMD) -0.16, 95% CI -0.34 to 0.02; N = 4 studies). Subgroup analyses revealed no significant between-group differences.

AUTHORS' CONCLUSIONS

Data from good quality randomised controlled trials show that NIV is beneficial as a first-line intervention in conjunction with usual care for reducing the likelihood of mortality and endotracheal intubation in patients admitted with acute hypercapnic respiratory failure secondary to an acute exacerbation of chronic obstructive pulmonary disease (COPD). The magnitude of benefit for these outcomes appears similar for patients with acidosis of a mild (pH 7.30 to 7.35) versus a more severe nature (pH < 7.30), and when NIV is applied within the intensive care unit (ICU) or ward setting.

Interfaces and ventilator settings for long-term noninvasive ventilation in COPD patients

Introduction

The establishment of high-intensity (HI) noninvasive ventilation (NIV) that targets elevated PaCO₂ has led to an increase in the use of long-term NIV to treat patients with chronic hypercapnic COPD. However, the role of the ventilation interface, especially in more aggressive ventilation strategies, has not been systematically assessed.

Methods

Ventilator settings and NIV compliance were assessed in this prospective cross-sectional monocentric cohort study of COPD patients with pre-existing NIV. Daytime arterialized blood gas analyses and lung function testing were also performed. The primary end point was the distribution among study patients of interfaces (full-face masks [FFMs] vs nasal masks [NMs]) in a real-life setting.

Results

The majority of the 123 patients studied used an FFM (77%), while 23% used an NM. Ventilation settings were as follows: mean ± standard deviation (SD) inspiratory positive airway pressure (IPAP) was 23.2±4.6 mbar and mean ± SD breathing rate was 16.7±2.4/minute. Pressure support ventilation (PSV) mode was used in 52.8% of patients, while assisted pressure-controlled ventilation (aPCV) was used in 47.2% of patients. Higher IPAP levels were associated with an increased use of FFMs (IPAP <21 mbar: 73% vs IPAP >25 mbar: 84%). Mean compliance was 6.5 hours/day, with no differences between FFM (6.4 hours/day) and NM (6.7 hours/day) users. PaCO₂ assessment of ventilation quality revealed comparable results among patients with FFMs or NMs.

Conclusion

This real-life trial identified the FFM as the predominantly used interface in COPD patients undergoing long-term NIV. The increased application of FFMs is, therefore, likely to be influenced by higher IPAP levels, which form part of the basis for successful application of HI-NIV in clinical practice.

[Non-invasive and invasive out of hospital ventilation in chronic respiratory failure : Consensus report of the working group on ventilation and intensive care medicine of the Austrian Society of Pneumology]

The current consensus report was compiled under the patronage of the Austrian Society of Pneumology (Österreichischen Gesellschaft für Pneumologie, ÖGP) with the intention of providing practical guidelines for out-of-hospital ventilation that are in accordance with specific Austrian framework parameters and legal foundations. The guidelines are oriented toward a 2004 consensus ÖGP recommendation concerning the setup of long-term ventilated patients and the 2010 German Respiratory Society S2 guidelines on noninvasive and invasive ventilation of chronic respiratory insufficiency, adapted to national experiences and updated according to recent literature. In 11 chapters, the initiation, adjustment, and monitoring of out-of-hospital ventilation is described, as is the technical equipment and airway access. Additionally, the different indications-such as chronic obstructive pulmonary diseases, thoracic restrictive and neuromuscular diseases, obesity hypoventilation syndrome, and pediatric diseases-are discussed. Furthermore, the respiratory physiotherapy of adults and children on invasive and noninvasive long-term ventilation is addressed in detail.

The cost-effectiveness of domiciliary non-invasive ventilation in patients with end-stage chronic obstructive pulmonary disease: a systematic review and economic evaluation

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is a chronic progressive lung disease characterised by non-reversible airflow obstruction. Exacerbations are a key cause of morbidity and mortality and place a considerable burden on health-care systems. While there is evidence that patients benefit from non-invasive ventilation (NIV) in hospital during an acute exacerbation, evidence supporting home use for more stable COPD patients is limited. In the U.K., domiciliary NIV is considered on health economic grounds in patients after three hospital admissions for acute hypercapnic respiratory failure.

OBJECTIVE

To assess the clinical effectiveness and cost-effectiveness of domiciliary NIV by systematic review and economic evaluation.

DATA SOURCES

Bibliographic databases, conference proceedings and ongoing trial registries up to September 2014.

METHODS

Standard systematic review methods were used for identifying relevant clinical effectiveness and cost-effectiveness studies assessing NIV compared with usual care or comparing different types of NIV. Risk of bias was assessed using Cochrane guidelines and relevant economic checklists. Results for primary effectiveness outcomes (mortality, hospitalisations, exacerbations and quality of life) were presented, where possible, in forest plots. A speculative Markov decision model was developed to compare the cost-effectiveness of domiciliary NIV with usual care from a UK perspective for post-hospital and more stable populations separately.

RESULTS

Thirty-one controlled effectiveness studies were identified, which report a variety of outcomes. For stable patients, a modest volume of evidence found no benefit from domiciliary NIV for survival and some non-significant beneficial trends for hospitalisations and quality of life. For post-hospital patients, no benefit from NIV could be shown in terms of survival (from randomised controlled trials) and findings for hospital admissions were inconsistent and based on limited evidence. No conclusions could be drawn regarding potential benefit from different types of NIV. No cost-effectiveness studies of domiciliary NIV were identified. Economic modelling suggested that NIV may be cost-effective in a stable population at a threshold of £30,000 per quality-adjusted life-year (QALY) gained (incremental cost-effectiveness ratio £28,162), but this is associated with uncertainty. In the case of the post-hospital population, results for three separate base cases ranged from usual care dominating to NIV being cost-effective, with an incremental cost-effectiveness ratio of less than £10,000 per QALY gained. All estimates were sensitive to effectiveness estimates, length of benefit from NIV (currently unknown) and some costs. Modelling suggested that reductions in the rate of hospital admissions per patient per year of 24% and 15% in the stable and post-hospital populations, respectively, are required for NIV to be cost-effective.

LIMITATIONS

Evidence on key clinical outcomes remains limited, particularly quality-of-life and long-term (> 2 years) effects. Economic modelling should be viewed as speculative because of uncertainty around effect estimates, baseline risks, length of benefit of NIV and limited quality-of-life/utility data.

CONCLUSIONS

The cost-effectiveness of domiciliary NIV remains uncertain and the findings in this report are sensitive to emergent data. Further evidence is required to identify patients most likely to benefit from domiciliary NIV and to establish optimum time points for starting NIV and equipment settings.

FUTURE WORK RECOMMENDATIONS

The results from this report will need to be re-examined in the light of any new trial results, particularly in terms of reducing the uncertainty in the economic model. Any new randomised controlled trials should consider including a sham non-invasive ventilation arm and/or a higher- and lower-pressure arm. Individual participant data analyses may help to determine whether or not there are any patient characteristics or equipment settings that are predictive of a benefit of NIV and to establish optimum time points for starting (and potentially discounting) NIV.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42012003286.

FUNDING

The National Institute for Health Research Health Technology Assessment programme.

Nasal highflow improves ventilation in patients with COPD

Background

Nasal highflow (NHF) provides a warmed and humidified air stream up to 60 L/min. Recent data demonstrated a positive effect in patients with acute hypoxemic respiratory failure, especially when caused by pneumonia. Preliminary data show a decrease in hypercapnia in patients with COPD. Therefore, NHF should be evaluated as a new ventilatory support device. This study was conducted to assess the impact of different flow rates on ventilatory parameters in patients with COPD.

Materials and methods

This interventional clinical study was performed with patients suffering from severe COPD. The aim was to characterize flow-dependent changes in mean airway pressure, breathing volumes, breathing frequency, and decrease in partial pressure of CO₂ (pCO₂). Mean airway pressure was measured in the nasopharyngeal space (19 patients). To evaluate breathing volumes, we used a polysomnographic device (18 patients). All patients received 20 L/min, 30 L/min, 40 L/min, and 50 L/min and – to illustrate the effects – nasal continuous positive airway pressure and nasal bilevel positive airway pressure. Capillary blood gas analyses were performed in 54 patients with hypercapnic COPD before and two hours after the use of NHF. We compared the extent of decrease in pCO₂ when using 20 L/min and 30 L/min. Additionally, comfort and dyspnea during the use of NHF were surveyed.

Results

NHF resulted in a minor flow dependent increase in mean airway pressure. Tidal volume increased, and breathing rate decreased. The calculated minute volume decreased under NHF breathing. In spite of this fact, hypercapnia decreased with increasing flow (20 L/min vs 30 L/min). Additionally, an improvement in dyspnea was observed. The rapid shallow breathing index shows a decrease when using NHF.

Conclusion

NHF leads to a flow-dependent reduction in pCO₂. This is most likely achieved by a washout of the respiratory tract and a functional reduction in dead space. In summary, NHF enhances effectiveness of breathing in patients with COPD, reduces pCO₂, the work of breathing, and rapid shallow breathing index as an indicator of respiratory work load.

Low-intensity noninvasive ventilation: Lower pressure, more exacerbations of chronic respiratory failure

BACKGROUND:

For patients with chronic respiratory failure (CRF) who are treated with noninvasive positive pressure ventilation (NPPV), a little is known regarding the effects of low-intensity NPPV (LI-NPPV) on the clinical course of CRF and the frequency of adjustments in these patients.

OBJECTIVES:

This study investigated the effects of LI-NPPV on the clinical course of patients with CRF as compared with patients who were treated with conventional NPPV (C-NPPV) and determined how frequently NPPV was adjusted during therapy.

METHODS:

Clinical data from 21 patients who received long-term NPPV were retrospectively analyzed. Patients were categorized into two groups based on the level of initial pressure support (PS): C-NPPV group (PS ≥ 10 cm H₂O) and LI-NPPV group (PS < 10 cm H₂O).

RESULTS:

Patients in the LI-NPPV group had significantly more exacerbations of CRF (P < 0.05). There was no significant difference in the number of patients who required adjustments of NPPV settings between the two groups. There was no significant difference in PaCO₂ levels 1 month after the start of NPPV between the two groups; however, PaCO₂ levels were significantly lower after 1 year in the C-group (P < 0.001). Seventy-one percent of LI-NPPV patients and 43% of C-NPPV patients needed NPPV adjustments.

CONCLUSIONS:

Attention should be paid to CRF patients who are initially administered LI-NPPV; they should be carefully observed because they can develop more exacerbations of CRF than patients undergoing C-NPPV. If possible, higher initial PS should be administered to prevent CRF exacerbations.

Update on clinical trials in home mechanical ventilation

Home mechanical ventilation (HMV) is an increasingly common intervention and is initiated for a range of pathological processes, including neuromuscular disease (NMD), chronic obstructive pulmonary disease (COPD) and obesity related respiratory failure. There have been important recent data published in this area, which helps to guide practice by indicating which populations may benefit from this intervention and the optimum method of setting up and controlling sleep disordered breathing. Recent superficially conflicting data has been published regarding HMV in COPD, with a trial in post-exacerbation patients suggesting no benefit, but in stable chronic hypercapnic patients suggesting a clear and sustained mortality benefit. The two studies are critiqued and the potential reasons for the differing results are discussed. Early and small trial data is frequently contradicted with larger randomised controlled trials and this has been the case with diaphragm pacing being shown to be potentially harmful in the latest data, confirming the importance of non-invasive ventilation (NIV) in NMD such as motor neurone disease. Advances in ventilator technology have so far appeared quicker than the clinical data to support their use; although small and often unblinded, the current data suggests equivalence to standard modes of NIV, but with potential comfort benefits that may enhance adherence. The indications for NIV have expanded since its inception, with an effort to treat sleep disordered breathing as a result of chronic heart failure (HF). The SERVE-HF trial has recently demonstrated no clear advantage to this technology and furthermore detected a potentially deleterious effect, with a worsening of all cause and cardiovascular mortality in the treated group compared to controls. The review serves to provide the reader with a critical review of recent advances in the field of sleep disordered breathing and HMV.

High Intensity Non-Invasive Positive Pressure Ventilation (HINPPV) for Stable Hypercapnic Chronic Obstructive Pulmonary Disease (COPD) Patients

Introduction: High intensity non-invasive positive pressure ventilation (HI-NPPV) is an algorithm of non-invasive ventilation that has been shown to improve partial pressure of carbon dioxide (PaCO₂), health-related quality of life and mortality in hypercapnic chronic obstructive pulmonary disease (COPD) patients. Objective: Assess 3 months of HI-NPPV in stable hypercapnic COPD patients. Methods: A single arm, non-randomized pilot study of HI-NPPV. Patients were eligible if they had clinically stable COPD and daytime arterial PaCO₂ >50 mmHg. Results: Nine patients completed therapy. Patient characteristics: 2 male: 7 female, mean age of 64.4 years (SD ±6.6), mean forced expiratory volume in 1 second (FEV₁) of 26% (SD±6.73), 8 patients on long term oxygen therapy (LTOT) and a median body mass index (BMI) of 26.6 (interquartile range [IQR] 25.5 - 32.5). Outcomes: There was a mean reduction in daytime PaCO₂ by 4.66 mmHg (p=0.01) and bicarbonate by 2.16 mmHg (p=0.005). There was no statistically significant difference in lung function, maximal inspiratory pressures or 6 minute walk distance. There was no statistically significant difference in sleep duration, efficiency or percentage of sleep stage 3 ( N3) or rapid eye movement (REM). The Chronic Respiratory Questionnaire (CRQ) showed a trend towards improvement with an increase of 2.69 points (p=0.054), the dyspnea domain showed a statistically significant improvement (p=0.03). The Calgary Sleep Apnea Quality of Life Index (SAQLI) detected an improvement in daily functioning (p=0.007). The Severe Respiratory Insufficiency (SRI) Questionnaire showed a trend to improvement overall (p=0.05). Four patients had COPD exacerbations during the follow up period. Conclusions: HI-NPPV is able to substantially reduce PaCO₂ in hypercapnic COPD patients; we detected a positive effect on quality of life measures with no significant change in sleep quality.

Parasternal electromyography to determine the relationship between patient-ventilator asynchrony and nocturnal gas exchange during home mechanical ventilation set-up

INTRODUCTION

Patient-ventilator asynchrony (PVA) can adversely affect the successful initiation of non-invasive home mechanical ventilation (HMV). The aim of this observational study was to quantify the prevalence of PVA during initiation of HMV and to determine the relationship between PVA and nocturnal gas exchange.

METHOD

Type and frequency of PVA were measured by surface parasternal intercostal muscle electromyography, thoracoabdominal plethysmography and mask pressure during initiation of HMV. Severe PVA was defined, as previously, as asynchrony affecting ≥10% of breaths.

RESULTS

28 patients (18 male) were enrolled aged 61±15 years and with a body mass index of 35±9 kg/m(2). Underlying diagnoses were neuromuscular disease with or without chest wall disease (n=6), obesity related chronic respiratory failure (n=12) and COPD (n=10). PVA was observed in all patients with 79% of patients demonstrating severe PVA. Triggering asynchrony was most frequent, observed in 24% (IQR: 11-36%) of breaths, with ineffective efforts accounting for 16% (IQR: 4-24%). PVA types were similar between disease groups, with the exception of auto-triggering, which was higher in patients with COPD (12% (IQR: 6-26%)). There was no correlation observed between PVA and time spent with oxygen saturations ≤90%, mean oxygen saturations or transcutaneous carbon dioxide levels during overnight ventilation.

CONCLUSIONS

Severe PVA was identified in the majority of patients, irrespective of pathophysiological disease state. This was not associated with ineffective ventilation as evidenced by gas exchange.

Long-term adherence with non-invasive ventilation improves prognosis in obese COPD patients

BACKGROUND AND OBJECTIVE

Long-term non-invasive ventilation (NIV) has become a widespread modality of treatment in chronic obstructive pulmonary disease (COPD) patients with chronic respiratory failure. However, benefits in terms of patient-related outcomes are still under debate. Both NIV adherence and heterogeneous responses in different COPD phenotypes may contribute to the difficulty of demonstrating NIV benefits. Our aim was to assess the impact of NIV adherence on the rate of hospitalization for acute exacerbation and death.

METHODS

This is a prospective multi-centre cohort study of COPD patients treated by long-term NIV. Comorbidities, anthropometrics, respiratory parameters were collected at inclusion in the study. Follow-up data included vital status, NIV adherence and hospitalizations. The influence of NIV adherence on prognosis was tested using an adjusted Cox model. Sensitivity analyses for obese and non-obese COPD subtypes were also conducted.

RESULTS

Two hundred thirteen patients (48% obese) were included with 45.5% died during 47.7 [interquartile range = 27.8; 73] months' follow-up. Survival was better in obese COPD than non-obese COPD. The use of NIV > 9 h/day was associated with an increased risk of death or hospitalization for acute exacerbation [HR = 1.6; 95CI: 1.1-2.4]. In obese COPD, this risk described a U-shaped curve from >1 to >9 h/day NIV usage with an improvement in prognosis when NIV adherence was > 5 h/day [HR = 0.5; 95CI: 0.2-0.9].

CONCLUSIONS

Adherence to NIV was associated with better prognosis only in obese COPD. NIV use > 9 h/day predicted poor outcomes.

Randomized trial of 'intelligent' autotitrating ventilation versus standard pressure support non-invasive ventilation: impact on adherence and physiological outcomes

BACKGROUND AND OBJECTIVE

Effective non-invasive ventilation (NIV) therapy is dependent on optimal ventilator settings to maximize clinical benefit and patient tolerance. Intelligent volume-assured pressure support (iVAPS) is a hybrid mode of servoventilation, providing constant automatic adjustment of pressure support (PS) to achieve a target ventilation determined by the patient's requirements. In a randomized crossover trial, we tested the hypothesis that iVAPS, with automated selection of ventilator settings, was non-inferior to standard PS ventilation, with settings determined by an experienced health-care professional, for controlling nocturnal hypoventilation in patients naive to NIV.

METHODS

Eighteen patients referred to a ventilator clinic with chronic obstructive or restrictive lung disease and newly diagnosed nocturnal hypoventilation (10 male, median (interquartile range): age 54(41-61) years, mean daytime PaO2 9.25(8.59-10.31) kPa, -PaCO2 6.38(5.93-6.65) kPa were randomized to iVAPS and standard PS. Polysomnography with transcutaneous CO2 monitoring was performed at baseline and 1 month after each treatment period. Nightly hours of therapy were recorded by the ventilator.

RESULTS

iVAPS delivered a lower median PS compared with standard PS (8.3(5.6-10.4) vs 10.0(9.0-11.4) cmH2 O; P = 0.001) for the same ventilatory outcome (mean overnight: SpO2 96(95-98) vs 96(93-97)%; P = 0.13 and PtcCO2 6.5(5.8-6.8) vs 6.2(5.8-6.9); P = 0.54). There was no difference in outcome between ventilator modes for spirometry, respiratory muscle strength, sleep quality, arousals or O2 desaturation index. Adherence was greater with iVAPS (5:40(4:42-6:49) vs 4:20(2:27-6:17) hh:mm/night; P = 0.004).

CONCLUSIONS

iVAPS servoventilation with automation of ventilation settings is as effective as PS ventilation initiated by a skilled health-care professional in controlling nocturnal hypoventilation and produced better overnight adherence in patients naive to NIV.

Noninvasive positive pressure ventilation in subjects with stable COPD: a randomized trial

BACKGROUND

The use of domiciliary noninvasive positive pressure ventilation (NPPV) in stable chronic obstructive pulmonary disease (COPD) with chronic hypercapnic respiratory failure has yielded variable effects on survival, quality of life, and dyspnea. We hypothesized that use of NPPV in stable COPD and partial pressure of carbon dioxide (PaCO2) <52 mmHg might result in improvement in quality of life and dyspnea.

METHODS

Thirty patients with stable COPD (forced expiratory volume in the first second <50% predicted and PaCO2 <52 mmHg) were prospectively randomized to receive domiciliary NPPV (bilevel positive airway pressure, 15/5 cm H2O) or usual therapy for 6 months. Measurements were made at baseline, 6 weeks, 3 months, and 6 months. Primary outcomes were quality of life as assessed by the Chronic Respiratory Disease Questionnaire (CRQ), and dyspnea as measured by the Transitional Dyspnea Index (TDI).

RESULTS

Fifteen subjects in the NPPV arm and 12 controls completed all the study visits. At 6 weeks and 3 months, the NPPV arm showed significant improvement in TDI total score. However, this effect persisted only in the TDI-Task at 6 months (P=0.03). NPPV use was associated with a small improvement in the CRQ-Mastery domain (0.6 versus -0.1, P=0.04). The arterial partial pressure of oxygen (PaO2) in the control arm worsened over the period of the study, whereas it remained stable in the NPPV arm (change -7.2 mmHg versus +2.1 mmHg, respectively, P=0.02).

CONCLUSION

NPPV resulted in a small improvement in quality of life indices in stable COPD patients with PaCO2 <52 mmHg. Future larger studies will clarify the role of NPPV in this stable subgroup of patients with COPD.

Changes in gastric pressure and volume during mechanical in-exsufflation

BACKGROUND/PURPOSE

A mechanical insufflator-exsufflator (MI-E) is used to replicate spontaneous cough in weak or neurologically impaired patients. Its use is often withheld after abdominal surgery because of concerns for potential wound dehiscence from abdominal distension or development of excessive abdominal positive pressure. We hypothesized that gastric pressure during MI-E use would not exceed usual pressures generated during a spontaneous cough.

METHODS

Thirteen subjects 0.8-23.1 years (mean 10.5 years) with neuromuscular weakness, pre-existing gastrostomy tube, and established MI-E routine were studied. A pressure transducer through the gastrostomy tube measured gastric pressure (Pgas) during MI-E treatment. Chest and abdominal volume change was assessed by respiratory inductance plethysmography. In three subjects, the same measurements were made during spontaneous cough.

RESULTS

The maximum Pgas was 24 cm with applied pressures of 20-40 cm. In the three subjects able to cough, the maximum Pgas achieved during the spontaneous maneuver was 25 cm, a value higher than they achieved with MI-E treatment.

CONCLUSION

MI-E resulted in less positive abdominal pressure than has been described in healthy subjects during spontaneous coughing. As such, use of an MI-E device should be considered safe to use in the post-operative period following abdominal surgery in patients with neuromuscular weakness.

Respiratory therapies for amyotrophic lateral sclerosis: a primer

Respiratory complications are a common cause of morbidity and mortality in amyotrophic lateral sclerosis (ALS). Treatment of respiratory insufficiency with noninvasive ventilation (NIV) improves ALS patients' quality of life and survival. Evidence-based practice guidelines for the management of ALS patients recommend treatment of respiratory insufficiency with NIV as well as consideration of insufflation/exsufflation to improve clearance of airway secretions. Despite these recommendations respiratory therapies remain underused. In this review we provide a practical guide for the clinician to prescribe and manage respiratory therapies for the patient with ALS.

Positive pressure for obesity hypoventilation syndrome

Obesity is increasing world-wide; obesity hypoventilation syndrome (OHS), formerly Pickwickian syndrome, has increased in parallel. Despite its prevalence, OHS has not been studied well, but there is abundant evidence that it is tightly linked with sleep-disordered breathing, most commonly obstructive sleep apnea. This article reviews the pathophysiology of OHS as well as the literature regarding the benefits of treating this disorder with positive airway pressure. We also emphasize that while positive pressure treatments may temporize cardiopulmonary disease progression, simultaneous pursuit of weight reduction is central to long-term management of this condition.

Effects of CPAP on gastric pouch pressure after bariatric surgery

BACKGROUND

The purpose of this study was to determine if the routine use of postoperative continuous positive airway pressure (CPAP) in patients undergoing laparoscopic Roux-en-Y gastric bypass (RYGB) is associated with an increase in transmural gastric pouch pressure, which may create the risk for anastomotic leak.

METHODS

Transmural gastric pressures (difference between gastric pouch and bladder pressures) were measured postoperatively [post-anesthesia recovery care unit (PACU) arrival (prior to initiation of CPAP), 5 min, 30 min, and PACU discharge] in 28 patients (19 patients used CPAP, 9 patients did not) following laparoscopic RYGB. Changes in pressure over time were assessed using a generalized estimating equation, taking into account the repeated measurements obtained for each subject. In all cases, two-tailed P values ≤0.05 were considered statistically significant.

RESULTS

Among patients that used CPAP, there were no changes in transmural pouch pressure from baseline at any point in time (P = 0.628). However, in patients that did not use CPAP, there was a trend towards increased transmural gastric/pouch pressure (P = 0.053), which could be attributed to a transient decrease in bladder pressure at the 5-min measurement interval.

CONCLUSIONS

Application of CPAP did not increase transmural gastric pouch pressure in our bariatric patients; therefore, its use in the post-RYGB patients does not pose a risk for pouch distension, which could lead to the disruption of anastomotic integrity.

Effects of long-term non-invasive home mechanical ventilation on chronic respiratory failure

OBJECTIVE

Chronic respiratory failure (CRF) is a syndrome defined by certain disturbances in arterial blood gases. Non-invasive mechanical ventilation (NIMV) is an increasingly used treatment modality in respiratory failure. The aim of this study was to investigate the long-term effects of NIMV on pulmonary function and survival of patients with CRF.

METHODS

The study enrolled 170 CRF patients who it was decided should receive long-term home mechanical ventilation. Patients were stratified into two distinct groups - Group I (patients for whom NIMV was recommended and who had used it) and Group II (patients for whom NIMV was recommended at least 1 year ago but who had not used it for various reasons). Best arterial blood gas and pulmonary function test values in the year before the NIMV recommendation were obtained from patient records. The same tests were performed at least 1 year (1-5 years) after initiation of NIMV therapy in Group I patients and at least 1 year (1-5 years) after prescription of the device in Group II.

RESULTS

In the assessments performed 1 year after NIMV recommendation, no difference was found between groups in terms of hospital admissions. However, in Group I, intra-group analysis showed a reduction in the number of hospitalizations 1 year after NIMV. A marked reduction in PaCO(2) level was found in Group I patients 1 year after NIMV therapy. Mean survival after NIMV recommendation was 40.27 +/- 3.56 months in Group I, and 27.35 +/- 3.68 months in Group II (log rank = 7.79; p = 0.005). It was found that survival time increased as duration of NIMV usage increased.

CONCLUSION

NIMV therapy has some important and significant benefits in patients with hypercapnic chronic respiratory failure. This study has some limitations in terms of patient selection, power analysis and survival analysis. To assess the effects of NIMV on mortality and pulmonary functions, the authors believe that there is need for prospective, controlled, multicentre studies with longer follow-up periods, improved adherence and novel ventilator modes and settings.

Long-term outcome of noninvasive positive pressure ventilation for obesity hypoventilation syndrome

BACKGROUND

Few data are available on the long-term outcome of noninvasive positive pressure ventilation (NPPV) for obesity hypoventilation syndrome (OHS). This study was designed to determine long-term survival, treatment adherence, and prognostic factors in patients with OHS in whom NPPV was initiated in an acute setting vs under stable clinical conditions.

METHODS

One hundred thirty consecutive patients with OHS (56 women) who started NPPV between January 1995 and December 2006 either under stable conditions (stable group, n = 92) or during ICU management of acute hypercapnic exacerbation (acute group, n = 38) were retrospectively analyzed.

RESULTS

Arterial blood gases and the Epworth sleepiness scale were both significantly improved after 6 months of NPPV. With a mean follow-up of 4.1 +/- 2.9 years, 24 (18.5%) patients died and 24 (18.5%) discontinued NPPV. On Kaplan-Meier analysis, 1-, 2-, 3-, and 5-year survival probabilities were 97.5%, 93%, 88.3%, and 77.3%, respectively. Mortality was lower than that described in a previous series of patients with untreated OHS. Supplemental oxygen therapy was the only independent predictor of mortality. The probability of continuing NPPV was 80% at 3 years with a high rate of daily use ( > 7 h). Female sex was predictive of lower long-term adherence to NPPV. The acute and stable groups did not differ in terms of arterial blood gases and Epworth sleepiness scale at 6 months, long-term survival, and treatment adherence.

CONCLUSIONS

The results of this study support long-term NPPV as an effective and well-tolerated treatment of OHS whether initiated in the acute or chronic setting.

Nocturnal noninvasive ventilation

Nocturnal noninvasive ventilation (NNV), the provision of ventilatory assistance via a noninvasive interface mainly during sleep, has assumed an important role in the management of chronic hypoventilatory syndromes. This review focuses on recent developments related to the use of NNV to treat various forms of chronic respiratory failure or insufficiency. In the past, NNV has been used mainly to treat respiratory insufficiency in patients with neuromuscular disease (NMD) or chest wall deformity; it should be instituted when these patients have orthopnea or daytime symptoms associated with nocturnal hypoventilation. An emerging application is to treat obesity-hypoventilation syndrome, particularly in continuous positive airway pressure (CPAP) failures. Additionally, it has a role in managing some patients with obstructive sleep apnea who are hypoventilating or find the lower expiratory pressure with bilevel positive pressure ventilators more tolerable than with CPAP alone. NNV to treat severe, stable COPD remains controversial, although a subgroup of patients with hypercapnea and sleep-disordered breathing (SDB) seems most likely to respond favorably. NNV to treat central SDB in patients with congestive heart failure continues to be investigated. Recent findings from a Canadian CPAP trial were disappointing, but preliminary results on a novel adaptive NNV mode are promising.

Continuous positive airway pressure (CPAP) induces early nasal inflammation

STUDY OBJECTIVES

To assess whether noninvasive application of nCPAP is a mechanical stimulus inducing early nasal inflammation.

DESIGN

Prospective controlled animal study.

SETTING

University laboratory.

PATIENTS OR PARTICIPANTS

32 male Sprague-Dawley rats (250-300 g).

INTERVENTIONS

The rats were anesthetized and subjected to nCPAP=10 cm H2O and sham-CPAP through a mask for 3 h and 5 h (n=8 each).

MEASUREMENTS AND RESULTS

After nCPAP or sham, nasal scraping was carried out to detect neutrophils, and septum and dorsal nasal concha were excised to assess gene expression of inflammatory markers by real time PCR. Percentage of neutrophils in nucleated cells in the nasal scrapings was significantly (P = 0.006) higher after 5 h of nCPAP (3.51% +/- 0.73%; m +/- SEM) than in the sham group (1.12% +/- 0.39%). When compared with sham, the mRNA of macrophage inflammatory protein-2 (MIP-2) in nasal tissue was significantly overexpressed after both 3 h (2.28-fold +/- 0.43-fold; P = 0.034) and 5 h (5.56-fold +/-1.88-fold; P = 0.002) of nCPAP=10 cm H2O. No significant changes were found in the gene expressions of tumor necrosis factor-alpha, nerve growth factor and tachykinin-1 receptor.

CONCLUSIONS

The compression applied by nCPAP (10 cm H2O, 5 h) on the nasal wall of healthy rats is a mechanical stimulus that triggers an early inflammatory process mediated by MIP-2, resulting in neutrophil extravasation.

Current status of noninvasive ventilation in stable COPD patients

Noninvasive ventilation (NIV) has been one of the major advances in respiratory medicine in the last decade. NIV improves quality of life, prolongs survival, and improves gas exchange and sleep quality in restrictive patients, but evidence available now does not allow us to establish clear criteria for prescribing NIV in patients with chronic respiratory failure due to COPD. On the basis of the available studies, NIV should not be used as a treatment of choice for all patients with COPD, even when disease is severe. However, there is more evidence that NIV has an important effect in these patients. In fact, a selected group of patients may well benefit from domiciliary mechanical ventilation, and we need to be able to identify who they are. Moreover, NIV can be a new strategy to improve exercise tolerance in COPD patients.

Predictors of long-term survival in patients with restrictive thoracic disorders and chronic respiratory failure undergoing non-invasive home ventilation

BACKGROUND AND OBJECTIVES

Non-invasive positive pressure ventilation (NPPV) is an established treatment in restrictive thoracic disorders (RTD) with chronic hypercapnic respiratory failure. The aim of this study was to identify predictors of long-term survival for patients on NPPV therapy.

METHODS

In a 10-year retrospective cohort of patients with RTD and chronic hypercapnic respiratory failure, survival and the predictive value of nocturnal and daytime blood gases, lung function and laboratory data measured before initiation of NPPV were assessed. The impact of ventilator settings and daily use of NPPV on survival were also evaluated. Patients were re-admitted every 6 months for follow-up assessment.

RESULTS

The study recruited 77 patients; 18 died during the study period and three ceased NPPV. Respiratory failure caused eight of the nine respiratory deaths (88.9%). One-, 2- and 5-year survival rates were 92.5%, 81.0% and 59.0%, respectively. In univariate analyses, higher night-time PaCO(2), base excess (night- and daytime) and lower Hb at baseline were associated with significantly worse survival (P < 0.05). Multivariate Cox regression analysis revealed night-time PaCO(2) as an independent predictor of survival (P = 0.042). The small differences in daily duration of use of NPPV and ventilator settings were not significantly related to survival. At follow up, significant improvements were observed for blood gases, lung and respiratory muscle function, as well as a decrease in Hb level (P < 0.01 each).

CONCLUSIONS

Base excess, Hb and particularly nocturnal PaCO(2) are relevant prognostic factors for survival in RTD and should be considered in assessing patients receiving NPPV.

Continuous positive airway pressure for the treatment of sleep apnea

Continuous positive airway pressure (CPAP) has become the treatment of choice for obstructive sleep apnea syndrome. Successful therapy with CPAP depends greatly on individual patient acceptance and compliance. Current indications for CPAP, including those for mild obstructive sleep apnea, will need to be revisited when results from the longitudinal follow-up of the Wisconsin Cohort and the Sleep Heart Health Study are made available.

Impact of noninvasive home ventilation on long-term survival in chronic hypercapnic COPD: a prospective observational study

AIMS

The long-term benefit from noninvasive ventilation (NIV) in chronic hypercapnic chronic obstructive pulmonary disease (COPD) remains uncertain.

METHODS

Within a prospective observational design, we compared the long-term survival of 140 patients with severe persistent hypercapnic COPD (FEV(1) 28.7 +/- 8.7% predicted; PaCO(2) 60.1 +/- 9.2 mmHg) with (n = 99) or without (n = 41) NIV. End-point was all-cause mortality, determined up to 4 years by Kaplan-Meier analysis. Additionally, Cox's proportional hazards regression and stratification by risk factors was performed. Patients were characterised by anthropometric and functional parameters, comorbidities and medical therapy.

RESULTS

Adherence in patients with NIV was high (88.9%), daily ventilator use being 6.4 +/- 2.6 h/day and inspiratory pressures 21.0 +/- 4.0 cmH(2)O. One- and 2-year survival rates were 87.7% and 71.8%, respectively, in patients with NIV vs. 56.7% and 42.0% in patients without NIV. Survival rates were significantly higher in patients with NIV compared to those without this therapy (p = 0.001; hazard ratio 0.380; 95% confidence interval 0.138-0.606). The difference between groups was still significant after adjustment for differences in baseline characteristics. Moreover, stratification by risk factors revealed beneficial effects, particularly in patients with high base excess (BE; > 8.9 mmol/l), low pH (< 7.41), FEV(1) (< 27.5%) haemoglobin (< 13.8 g/dl) or large hyperinflation (residual volume-to-total lung capacity > 189% predicted) upon inclusion (p < 0.05 each).

CONCLUSION

In patients with severe chronic hypercapnic COPD receiving NIV at high inspiratory pressure levels and showing high adherence to this therapy, long-term survival was significantly higher than in non-ventilated patients. Patients displaying more severe disease according to known risk factors seemed to benefit most from long-term NIV.

Neonatal nasal intermittent positive pressure ventilation: what do we know in 2007?

Although neonatal nasal intermittent positive pressure ventilation (NIPPV) is widely used today, its place in neonatal respiratory support is yet to be fully defined. Current evidence indicates that NIPPV after extubation of very premature infants reduces the rate of reintubation. However, much is still not known about NIPPV including its mechanisms of action. It may improve pulmonary mechanisms, tidal volume and minute ventilation but more studies are required to confirm these findings. There is some evidence that NIPPV marginally improves gas exchange. More research is needed to establish which device is best, what settings to use or whether to use synchronised rather than non-synchronised NIPPV, and about the way to wean NIPPV. Future studies should enrol sufficient infants to detect uncommon serious complications and include long-term follow up to determine important neurodevelopment and pulmonary outcomes.

Predictors of Survival in COPD Patients With Chronic Hypercapnic Respiratory Failure Receiving Noninvasive Home Ventilation

BACKGROUND

Patients with COPD and chronic hypercapnic respiratory failure (CHRF) are at high risk, and noninvasive ventilation at home is increasingly being used. Knowledge of prognostic parameters under these conditions is limited but may be clinically helpful and highlight the role of noninvasive ventilation.

METHODS

In 188 patients with COPD (mean +/- SD FEV1, 31.0 +/- 9.6% of predicted; PaCo2, 56.3 +/- 9.4 mm Hg) discharged from the hospital receiving NIV between July 1994 and July 2004, the prognostic value of body mass index (BMI), lung function, laboratory parameters, and blood gas levels was assessed by univariate and multivariate Cox regression analyses. Moreover, the impact of changes in risk factors on mortality assessed 6.7 +/- 2.8 months after the initiation of noninvasive ventilation was evaluated.

RESULTS

Overall, the mortality rate during follow-up (duration, 32.2 +/- 24.3 months) was 44.7%, with 1-year, 2-year, and 5-year survival rates of 84.0%, 65.3%, and 26.4%. Deaths resulted predominantly from respiratory causes (73.8%). Univariate regression analyses revealed age, BMI, hemoglobin, FEV1, specific airway resistance, residual volume (RV)/total lung capacity (TLC), pH, and base excess (BE) to be associated with prognosis (p < 0.01 each), whereas multivariate analysis identified only age, BMI, RV/TLC, and BE as independent predictors (p < 0.05). In patients at risk (BMI < 25 km/m2, RV/TLC >or= 73%, or BE >or= 9 mmol/L), changes in these predictors were also associated with survival.

CONCLUSIONS

In patients with COPD and CHRF, nutritional status, hyperinflation, and BE, which turned out to be reliable and consistent markers in CHRF, were independent prognostic factors for mortality. These data favor a multidimensional approach in these patients, including the use of noninvasive ventilation.

Non-invasive home mechanical ventilation: Effectiveness and efficiency of an outpatient initiation protocol compared with the standard in-hospital model

OBJECTIVE

To compare the effectiveness and efficiency of an initiation protocol for non-invasive home mechanical ventilation (NIHMV) carried out at a pulmonary outpatient clinic with the standard in-hospital model.

METHODS

Prospective, observational study.

POPULATION

16 patients divided into two groups: (A) outpatient protocol (n=9); and (B) standard in-hospital initiation with an elective admission (n=7).

INSTRUMENTATION

at baseline condition and treatment starting, arterial blood gases and nocturnal pulse-oximetry were performed. At the end of follow-up, arterial blood gases and patient compliance (ventilator's built-in counter) was determined. Efficiency was evaluated by calculating cost savings per ventilated patient for the financier and accumulated days of hospitalization saved.

RESULTS

No differences in baseline conditions were observed. Ventilation was effective in the two groups: a significant decrease in PaCO(2) and an increase in mean nocturnal oxygen saturation were observed after initiating ventilation. (Group A: PaCO(2):42.9+/-1.5; SpO(2):91.9+/-1.9; Group B:PaCO(2):44.3+/-6; SpO(2):91.9+/-2.7). At three months the effectiveness of ventilation and the number of hours of ventilation was equivalent in all groups. The new model cut costs for the health care financier by 50%. The outpatient sessions saved 63 days of hospitalization.

CONCLUSIONS

(1) Outpatient initiation is an effective and efficient alternative to the traditional in-hospital method for NIHMV. (2) The outpatient protocol represents a substantial saving for the financier.

Outcome of non-invasive domiciliary ventilation in elderly patients

STUDY OBJECTIVES

To analyze the short- and long-term effects of domiciliary non-invasive ventilation (NIV) in the elderly.

METHODS

From 1990 to 2005 all patients who initiated NIV at age 75 or older were included in the study. The mean follow-up period was 36 (24) months. Data were obtained from a database record.

RESULTS

Forty-three patients, mean age 77 (1.9) years and hypercapnic respiratory failure secondary to restrictive, neuromuscular or hypoventilatory disease were included. The short-term effects included a significant improvement in arterial blood gases and nocturnal desaturations during NIV compared to baseline: PaO(2) increased a mean of 19 mmHg (P<0.0001), PaCO(2) decreased a mean of 16 mmHg (P<0.0001) and nocturnal time with SaO(2)<90% decreased a mean of 72% (P<0.0001). Arterial blood gases while breathing room air also improved significantly at 6 months after NIV initiation. Five patients (11%) discontinued treatment; this group did not differ from patients who continued NIV. Mean compliance was 8.3 (3.1)h/day. In the long-term effects, we observed that the initial improvement of arterial blood gases breathing room air was maintained throughout the followup period. The number of hospital admissions and days of hospital stay decreased significantly (P<0.0001 and 0.001, respectively) after NIV initiation. The poorest survival was observed in ALS patients (median 10.9 (2.3) months) significantly lower than the survival for the other diagnostic groups (median 58.5 (4.8) months), P=0.0013.

CONCLUSIONS

NIV is an effective treatment in the elderly. It improves arterial blood gases and nocturnal desaturations, decreases hospital admissions and is associated with long survival. So advanced age should not be considered as an exclusion criteria to prescribe NIV.

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

BACKGROUND/PURPOSE

This study was designed to investigate the effects of 6 months of nocturnal nasal positive pressure ventilation (NNPPV) on respiratory muscle function and exercise capacity in patients with chronic respiratory failure.

METHODS

A prospective, randomized, controlled design was used. Twenty-nine patients with chronic respiratory failure were enrolled and allocated to either the NNPPV (n = 14) or control group (n = 15). Patients in the NNPPV group received bi-level positive pressure ventilation via nasal mask for 6 consecutive months. Arterial blood gas, respiratory muscle assessment and 6-minute walk test (6MWT) were performed before and after the 6-month NNPPV intervention. Respiratory muscle function was assessed using the variables of maximal inspiratory pressure (Pimax), maximal expiratory pressure (Pemax), and maximum voluntary ventilation (MVV).

RESULTS

Subjects in the NNPPV group showed a significant improvement in blood gas exchange and increased 6-minute walk distance (6MWD) compared to baseline and the control group. The 6MWD was significantly increased from 257.1 +/- 114.1 to 345.2 +/- 109.9 m (34.3%) in the NNPPV group. NNPPV also significantly improved MVV and Pimax relative to baseline. MVV was significantly increased from 19.2 +/- 6.5 to 22.3 +/- 7.1 L/min (16.1%) in the NNPPV group (p < 0.05). Furthermore, there was a significant correlation between the magnitude of MVV improvement and 6MWD change.

CONCLUSION

The 6-month NNPPV treatment significantly decreased the partial pressure of carbon dioxide and improved daytime respiratory muscle function, thus contributing to exercise-capacity increase in patients with chronic respiratory failure.

Impact of Ventilation Parameters and Duration of Ventilator Use on Non-Invasive Home Ventilation in Restrictive Thoracic Disorders

BACKGROUND

Non-invasive positive pressure ventilation (NPPV) is an accepted treatment option for chronic ventilatory failure due to restrictive thoracic disorders.

OBJECTIVE

The impact of ventilation setting and the duration of ventilator use on changes in physiological and functional parameters has not yet been evaluated.

METHODS

Effects of NPPV on body plethysmographic parameters, blood gas tension and inspiratory muscle function up to 12 months were analyzed in 44 patients with thoracic cage abnormalities in a clinical stable condition. Furthermore, the influence of ventilator parameters and the duration of ventilator use on these changes was determined.

RESULTS

A significant improvement in blood gas parameters (PaCO(2), PaO(2) and base excess; p < 0.001), lung volumes (VC, TLC and FEV(1); p < 0.001) and inspiratory muscle function (PI(max), P(0.1); p < 0.01 and p < 0.05) was found after 3.8 +/- 0.8 months of treatment. As shown by a subgroup analysis, changes were already achieved within the first 3 months of NPPV and then remained stable over time. Improvements in VC were positively correlated with IPAP (r = 0.55; p < 0.001). Reduction in PaCO(2) was positively correlated with the quotient (IPAP - EPAP)/weight (r = 0.55; p < 0.001). No correlation could be detected between changes in functional parameters and the duration of ventilator use.

CONCLUSIONS

NPPV can improve blood gas parameters, lung volume and inspiratory muscle function in thoracic restrictive disorders. To best utilize the potential of NPPV treatment, it seems to be more effective to optimize pressure levels than to extend the duration of ventilation.

Titration of non-invasive positive pressure ventilation in chronic respiratory failure

Non-invasive ventilation (NIV) is widely used for acute and chronic respiratory failure. If arterial blood gas tensions do not improve, the level of support can be increased. However, there may be a limit above which increasing ventilatory support leads only to greater interface leak with no improvement in ventilation. The aim of this study was to establish whether there is such a limit. During a daytime study in 24 ventilated stable patients (10 with chronic obstructive pulmonary disease (COPD), 14 with chest wall deformity, CWD), inspiratory pressures up to 20 cm H(2)O and set tidal volumes up to 10 ml kg(-1) were associated with mask leak of <5 l min(-1). Although leak increased with higher levels of support, there was still an increase in minute ventilation. The mean (2 sd) tolerated pressure was 24 cm H(2)O (8-40) in both groups, and set tidal volume 12.7 ml kg(-1) (5.0-20.4) in CWD and 9.6 ml kg(-1) (3.9-14.8) in COPD. Measures of respiratory effort were significantly reduced at all levels with both forms of ventilatory support. There is debate about whether the therapeutic aim of NIV should be to reduce respiratory muscle effort, or to reverse nocturnal hypoventilation. We conclude that if the primary aim is to improve arterial blood gas tensions and this is not achieved, higher levels of ventilation can be obtained using greater pressure or volume, despite additional interface leak. If the aim is to abolish muscle effort completely, there is little to be gained by increasing the level of inspiratory pressure above 20 (CWD) or 25 (COPD) cm H(2)O.

Comparative study of two different modes of noninvasive home mechanical ventilation in chronic respiratory failure

STUDY OBJECTIVE

Two modes of noninvasive home mechanical ventilation (NIHMV) with volumetric ventilators were compared in patients with chronic respiratory failure.

DESIGN

Retrospective, parallel-group, comparative study.

SETTING

Third-level teaching Hospital in Barcelona (Spain).

PATIENTS AND METHODS

We studied 110 patients with chronic hypercapnic respiratory failure secondary to neuromuscular disease, kyphoscoliosis or post-tuberculosis sequelae, starting NIHMV with volumetric ventilators. The assist/control (A/C) ventilation mode was used in 45 patients and the control (C) mode in 65 patients. Clinical characteristics, pulmonary function results and arterial blood gas findings were assessed in each patient before establishing ventilation and at 6 and 12 months after. The patient's satisfaction with ventilation, the time required for adaptation, and compliance with the prescription were also assessed.

MEASUREMENTS AND RESULTS

Significant improvements in PaO(2) and PaCO(2) (P<0.001) were found at 6 and 12 months with both modes of mechanical ventilation. There were no significant differences between the two modes for pulmonary function or blood gas parameters with the exception of maximum inspiratory pressure (MIP) in patients receiving the C mode, which was significantly different as compared to the baseline value after 12 months of use (mean+/-sd: 36.6+/-14.8 and 44.7+/-24.2 cmH(2)O, respectively; P=0.010). No significant differences were found in adaptation, compliance with ventilation or patient satisfaction between the two modes studied.

CONCLUSIONS

According to several factors analysed, results with the A/C or C mode used with volumetric ventilators appear to be comparable in patients with chronic respiratory disease receiving NIHMV. Choice of mode will depend on the acquired experience of the prescribing physicians in each centre.

Nocturnal non-invasive positive pressure ventilation: Physiological effects on spontaneous breathing

The dynamic process of how non-invasive positive pressure ventilation (NPPV) improves spontaneous ventilation is unclear. Therefore, daytime trends of blood gases and breathing pattern were assessed by measurements 0, 0.5, 1, 3, 7, 11 and 15 h after cessation of nocturnal controlled NPPV in patients with chronic hypercapnic respiratory failure. Twelve patients (six COPD/six restrictive) who were established on NPPV and 12 controls (six COPD/six restrictive) completed. PaCO2 decreased during controlled NPPV (P < 0.02). PaCO2 additionally decreased step by step during the first 3 h of spontaneous breathing after switching from NPPV to spontaneous breathing (P < 0.05), but remained unchanged in controls. The PaCO2 decrease was due to a stepwise increase in tidal volume (P < 0.05) at an unchanged breathing frequency. Accordingly, minute ventilation also stepwise increased (P < 0.03). There were no significant changes in controls. Improvements of PaCO2 and tidal volume occurred even after 5.7 +/- 3.1 days following first NPPV trials, but became more evident after 2 months. Maximal inspiratory mouth pressures increased in chronic obstructive pulmonary disease (COPD) patients (P < 0.05), and respiratory drive increased in restrictive patients (P < 0.05) following 2 months of NPPV. Lung function parameters and inspiratory impedance remained unchanged. Improvements in health-related quality of life were evident and were correlated to the decline of elevated bicarbonate levels (r = 0.72, P < 0.01). In conclusion, there is a stepwise adaptation process lasting 3h when switching from nocturnal controlled NPPV to daytime spontaneous breathing in which tidal volume increases and PaCO2 drops after an initial PaCO2 decrease while on NPPV.

Home mechanical ventilatory support in patients with restrictive ventilatory disorders: A 48-year experience

We performed a retrospective analysis to the effects of negative pressure ventilation (NPV), tracheal intermittent positive pressure ventilation (TIPPV), and nasal intermittent positive pressure ventilation (NIPPV, volume or pressure-controlled ventilatory mode), in 114 patients with restrictive ventilatory disorders instituted in our hospital from 1956 until 2005. The patients were assigned on "ad hoc" basis to NPV, TIPPV, or NIPPV. All patients were subdivided in an idiopathic kyphoscoliosis group (IK, n=64), a post-poliomyelitis syndrome group (PP, n=30), or a miscellaneous group (M, n=20). The patients in the PP group had higher survival rates compared to the IK patients (P<0.05), while the M patients had the lowest survival rates (P<0.01). Both NPV (P<0.01) and TIPPV (P<0.05) lead to a decrease in PaCO2 after 9 months compared to baseline. This decrease in PaCO2 was still present after 5 years NPV (P<0.001) and TIPPV (P<0.05). NIPPV lead to an improvement in pulmonary function (P<0.05) and arterial blood gases (P<0.001) after 9 months compared to baseline. After 5 years NIPPV, the arterial blood gases were still significantly improved compared to baseline (P<0.01). Both volume-controlled and pressure-controlled ventilation improved pulmonary function and arterial blood gases.

CONCLUSION

Long-term home mechanical ventilatory support by both NPV and positive pressure ventilation is effective in patients with IK, PP syndrome, and a M group, even after a period of 5 years.