Long-term controlled trial of nocturnal nasal positive pressure ventilation in patients with severe COPD

Treatment of respiratory failure in COPD

Patients with advanced COPD and acute or chronic respiratory failure are at high risk for death. Beyond pharmacological treatment, supplemental oxygen and mechanical ventilation are major treatment options. This review describes the physiological concepts underlying respiratory failure and its therapy, as well as important treatment outcomes. The rationale for the controlled supply of oxygen in acute hypoxic respiratory failure is undisputed. There is also a clear survival benefit from long-term oxygen therapy in patients with chronic hypoxia, while in mild, nocturnal, or exercise-induced hypoxemia such long-term benefits appear questionable. Furthermore, much evidence supports the use of non-invasive positive pressure ventilation in acute hypercapnic respiratory failure. It application reduces intubation and mortality rates, and the duration of intensive care unit or hospital stays, particularly in the presence of mild to moderate respiratory acidosis. COPD with chronic hypercapnic respiratory failure became a major indication for domiciliary mechanical ventilation, based on pathophysiological reasoning and on data regarding symptoms and quality of life. Still, however, its relevance for long-term survival has to be substantiated in prospective controlled studies. Such studies might preferentially recruit patients with repeated hypercapnic decompensation or a high risk for death, while ensuring effective ventilation and the patients’ adherence to therapy.

High-intensity non-invasive positive pressure ventilation for stable hypercapnic COPD

BACKGROUND

The objective of the present analysis is to describe the outcomes of high-intensity non-invasive positive pressure ventilation (NPPV) aimed at maximally decreasing PaCO(2) as an alternative to conventional NPPV with lower ventilator settings in stable hypercapnic COPD patients.

METHODS

Physiological parameters, exacerbation rates and long-term survival were assessed in 73 COPD patients (mean FEV(1) 30+/-12 %predicted) who were established on high-intensity NPPV due to chronic hypercapnic respiratory failure between March 1997 and May 2006.

RESULTS

Controlled NPPV with breathing frequencies of 21+/-3 breath/min and mean inspiratory/expiratory positive airway pressures of 28+/-5/5+/-1 cmH(2)O led to significant improvements in blood gases, lung function and hematocrit after two months. Only sixteen patients (22%) required hospitalisation due to exacerbation during the first year, with anaemia increasing the risk for exacerbation. Two- and five-year survival rates of all patients were 82% and 58%, respectively. The five year survival rate was 32% and 83% in patients with low (< or =39%) and high (> or =55%) hematocrit, respectively.

CONCLUSION

High-intensity NPPV improves blood gases, lung function and hematocrit, and is also associated with low exacerbation rates and a favourable long-term outcome. The current report strongly emphasises the need for randomised controlled trials evaluating the role of high-intensity NPPV in stable hypercapnic COPD patients.

Noninvasive home ventilation for chronic obstructive pulmonary disease: indications, utility and outcome

PURPOSE OF REVIEW

Despite its widespread use, the role of noninvasive home mechanical ventilation for the management of severe chronic obstructive pulmonary disease and chronic hypercapnic respiratory failure is still controversial. The majority of randomized controlled trials show methodological weaknesses, including issues of patient selection, insufficient pressure support and poor adherence to therapy. Data from short-term trials, while assuring effective ventilation, are encouraging by demonstrating physiological improvements, in line with benefits regarding symptoms and quality of life. The role of home mechanical ventilation for long-term survival is, however, still unclear.

RECENT FINDINGS

Possible indications of home mechanical ventilation, physiological concepts underlying the effects of noninvasive ventilation and their impact on clinically important long-term outcomes are reported.

SUMMARY

Due to systemic involvement, the decision to undertake home mechanical ventilation should probably not be based on symptomatic chronic hypercapnia alone, but on a broader spectrum of factors. In particular, patients with repeated hypercapnic decompensation are at high risk for death and obvious candidates for home mechanical ventilation. Beyond restoration of chemosensitivity, changes in breathing pattern and a reduction of mechanical load are likely mechanisms of home mechanical ventilation, inducing symptom relief and improving functional reserve. To fully utilize its potential, high pressure levels are required. Future prospective controlled studies should take into account these experiences.

Clinical review: long-term noninvasive ventilation

Noninvasive positive ventilation has undergone a remarkable evolution over the past decades and is assuming an important role in the management of both acute and chronic respiratory failure. Long-term ventilatory support should be considered a standard of care to treat selected patients following an intensive care unit (ICU) stay. In this setting, appropriate use of noninvasive ventilation can be expected to improve patient outcomes, reduce ICU admission, enhance patient comfort, and increase the efficiency of health care resource utilization. Current literature indicates that noninvasive ventilation improves and stabilizes the clinical course of many patients with chronic ventilatory failure. Noninvasive ventilation also permits long-term mechanical ventilation to be an acceptable option for patients who otherwise would not have been treated if tracheostomy were the only alternative. Nevertheless, these results appear to be better in patients with neuromuscular/-parietal disorders than in chronic obstructive pulmonary disease. This clinical review will address the use of noninvasive ventilation (not including continuous positive airway pressure) mainly in diseases responsible for chronic hypoventilation (that is, restrictive disorders, including neuromuscular disease and lung disease) and incidentally in others such as obstructive sleep apnea or problems of central drive.

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.

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.

Respiratory disorders during sleep in chronic obstructive pulmonary disease

Patients with COPD may show slow, progressive deteriorations in arterial blood gases during the night, particularly during rapid eye movement (REM) sleep. This is mainly due to hypoventilation, while a deterioration of ventilation/perfusion mismatch plays a minor role. The severity of gas exchanges alterations is proportional to the degree of impairment of diurnal pulmonary function tests, particularly of partial pressure of oxygen (PaO₂) and of carbon dioxide (PaCO₂) in arterial blood, but correlations between diurnal and nocturnal blood gas levels are rather loose. Subjects with diurnal PaO₂ of 60–70 mmHg are distinguished in “desaturators” and “nondesaturators” according to nocturnal oxyhemoglobin saturation behavior. The role of nocturnal hypoxemia as a determinant of alterations in sleep structure observed in COPD is dubious. Effects of the “desaturator” condition on pulmonary hemodynamics, evolution of diurnal blood gases, and life expectancy are also controversial. Conversely, it is generally accepted that occurrence of sleep apneas in COPD is associated with a worse evolution of the disease. Nocturnal polysomnographic monitoring in COPD is usually performed when coexistence of sleep apnea (“overlap syndrome”) is suspected, while in most other cases nocturnal oximetry may be enough. Nocturnal oxygen attenuates sleep desaturations among stable patients, without increases in PaCO₂ of clinical concern. Nocturnal treatment with positive pressure ventilators may give benefit to some stable hypercapnic subjects and patients with the overlap syndrome.

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.

COPD exacerbations: defining their cause and prevention

Exacerbations of chronic obstructive pulmonary disease (COPD) are episodes of worsening of symptoms, leading to substantial morbidity and mortality. COPD exacerbations are associated with increased airway and systemic inflammation and physiological changes, especially the development of hyperinflation. They are triggered mainly by respiratory viruses and bacteria, which infect the lower airway and increase airway inflammation. Some patients are particularly susceptible to exacerbations, and show worse health status and faster disease progression than those who have infrequent exacerbations. Several pharmacological interventions are effective for the reduction of exacerbation frequency and severity in COPD such as inhaled steroids, long-acting bronchodilators, and their combinations. Non-pharmacological therapies such as pulmonary rehabilitation, self-management, and home ventilatory support are becoming increasingly important, but still need to be studied in controlled trials. The future of exacerbation prevention is in assessment of optimum combinations of pharmacological and non-pharmacological therapies that will result in improvement of health status, and reduction of hospital admission and mortality associated with COPD.

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.

Non-invasive positive ventilation in the treatment of sleep-related breathing disorders

This chapter addresses the use of long-term non-invasive positive pressure ventilation (NIPPV) (to the exclusion of continuous positive airway pressure) in the different clinical settings in which it is currently proposed: principally in diseases responsible for hypoventilation characterized by elevated PaCO(2). Nasal masks are predominantly used, followed by nasal pillow and facial masks. Mouthpieces are essentially indicated in case daytime ventilation is needed. Many clinicians currently prefer pressure-preset ventilator in assist mode as the first choice for the majority of the patients with the view of offering better synchronization. Nevertheless, assist-control mode with volume-preset ventilator is also efficient. The settings of the ventilator must insure adequate ventilation assessed by continuous nocturnal records of at least oxygen saturation of haemoglobin-measured by pulse oximetry. The main categories of relevant diseases include different types of neuromuscular disorders, chest-wall deformities and even lung diseases. Depending on the underlying diseases and on individual cases, two schematic situations may be individualized. Either intermittent positive pressure ventilation (IPPV) is continuously mandatory to avoid death in the case of complete or quasi-complete paralysis or is used every day for several hours, typically during sleep, producing enough improvement to allow free time during the daylight in spontaneous breathing while hypoventilation and related symptoms are improved. In case of complete or quasi-complete need of mechanical assistance, a tracheostomy may become an alternative to non-invasive access. In neuromuscular diseases, in kyphosis and in sequela of tuberculosis patients, NIPPV always significantly increases survival. Conversely, no data support a positive effect on survival in chronic obstructive pulmonary disease.

Effects of Nocturnal Noninvasive Mechanical Ventilation on Heart Rate Variability of Patients With Advanced COPD

BACKGROUND

Cardiovascular comorbidities have a negative impact on the health status and prognosis of patients with COPD. We determined whether nocturnal noninvasive (positive) mechanical ventilation (NIMV) can improve heart rate variability (HRV), decrease circulating natriuretic peptide levels, and improve functional performance of patients with very advanced COPD.

METHODS

A randomized, double-blind, parallel controlled trial was conducted in 23 participants with stable but advanced COPD. Participants received standard medical therapy plus nocturnal NIMV or standard medical therapy plus sham NIMV for 3 months.

RESULTS

After 3 months of NIMV therapy, the 24-h triangular interpolation of N-N intervals increased from 322 to 473 ms (p = 0.034), the 24-h HRV index (HRVI) increased from 21.8 to 29.9 ms (p = 0.035), nocturnal HRVI increased from 6.1 to 8.0 ms (p = 0.026), and the SD of the average N-N interval increased from 37 to 41 ms (p = 0.020). None of these indexes changed significantly in the control group. Additionally, compared with the control group, the pro-atrial natriuretic peptide levels declined significantly in the NIMV group (p = 0.013).

CONCLUSIONS

NIMV applied nocturnally over 3 months may improve HRV, reduce circulating natriuretic peptide levels, and enhance the functional performance of patients with advanced but stable COPD. While not definitive due to small sample size, these data suggest that nocturnal NIMV may reduce the impact of cardiac comorbidities in COPD patients.

[Follow-up criteria for community acquired pneumonias and acute exacerbations of chronic obstructive pulmonary disease]

The follow-up of Community Acquired Pneumonias (CAP) and Acute Exacerbations of Chronic Obstructive Pulmonary Diseases (AECOPD) differs with the setting of care, but overall calls upon the same investigations as the initial evaluations. In the event of initial ambulatory care, the evaluation is carried out primarily on clinical data, at the 2 or 3rd day for the CAP, at the 2nd to 5th day for the AECOPD. In the event of unfavourable evolution, or from the start in the most severe cases, the follow-up is carried out in hospital; clinical evaluation is readily daily, and all the more frequent that the clinical condition is worrying because of the severity or risk factors. The investigations will be limited to those initially abnormal in the event of favourable evolution; on the contrary, unfavourable evolution can justify new investigations which depend on clinical characteristics. Remotely, i.e. 4 to 8 weeks later, must be checked the return at the baseline clinical state, a chest X-ray (CAP), spirometry and arterial blood gas (AECOPD), even bronchoscopy and thoracic CT-scan.

Devenir des patients BPCO traités par ventilation non invasive prolongée à domicile

BACKGROUND

The use of domiciliary non-invasive positive pressure ventilation (NIPPV) is still controversial in stable hypercapnic COPD.

METHODS

Records of COPD patients who received home NIPPV from 1990 to 2002 either following an acute exacerbation or because of stable hypercapnia were retrospectively reviewed.

RESULTS

Thirty-seven patients receiving long term oxygen therapy for 50 +/- 47 months were included. At inclusion, their mean +/- SD: FEV1 was 27 +/- 9% predicted, inspiratory capacity was 45 +/- 14% predicted, PaO2 breathing room air was 50 +/- 10 mm Hg, PaCO2 breathing room air = 53 +/- 8 mm Hg, PaCO2 with oxygen was 60 +/- 9 mm Hg. Median survival with NIPPV was 41 months. The 1-year, 3-year and 5-year survival rates with NIPPV were 92%, 62% and 24% respectively. Twelve months after onset of home NIPPV, PaCO2 breathing room air and with oxygen were significantly lower (47 +/- 8 mm Hg, p = 0.028 and 53 +/- 8 mm Hg, p = 0.005, respectively), inspiratory capacity was significantly improved (54 +/- 18% predicted, p = 0.033).

CONCLUSION

This study suggests that home NIPPV allows a lasting physiological stabilization in selected COPD patients, particularly those with an advanced disease, by reducing hypercapnia and improving inspiratory capacity.

COPDX: an update of guidelines for the management of chronic obstructive pulmonary disease with a review of recent evidence

Long-acting beta(2) agonists are an effective and convenient treatment for chronic obstructive pulmonary disease (COPD), but do not significantly improve lung function. The long-acting anticholinergic tiotropium, which can be taken once daily, decreases exertional dyspnoea and increases endurance by reducing hyperinflation. The role in COPD of the combination of a long-acting beta(2) agonist and a glucocorticoid in a single inhaler remains unclear. The minimum duration of an effective pulmonary rehabilitation program that includes exercise training is 6 weeks. Long-term treatment with inhaled glucocorticoids may reduce the rate of decline in lung function, but the effect is small. Aminophylline should no longer be routinely used in acute exacerbations of COPD. Non-invasive positive pressure ventilation (NPPV) reduces mortality and hospital stay in patients with acute hypercapnic ventilatory failure; it is also an effective weaning strategy for patients who require intubation. Further studies are required to clarify the role of NPPV in the long-term management of stable COPD.

Prolonged invasive ventilation following acute ventilatory failure in COPD: weaning results, survival, and the role of noninvasive ventilation

BACKGROUND

Invasive ventilation for COPD has significant mortality, and weaning can be difficult. At Papworth Hospital, we provide a specialist weaning service using noninvasive ventilation (NIV) for patients requiring prolonged invasive ventilation after recovery from acute illness. We analyzed our results for patients with COPD to identify factors associated with weaning outcome and survival.

METHODS

A retrospective analysis was conducted of COPD patients admitted for weaning from invasive ventilation, from 1992 to 2003. Weaning success and survival were assessed. Associations were sought between these outcomes and age, sex, spirometry, arterial blood gas levels, APACHE (acute physiology and chronic health evaluation) II score, length of stay (LOS), and the use of NIV and long-term oxygen therapy.

RESULTS

Sixty-seven patients were identified, all of whom were receiving tracheostomy ventilation on transfer to the Respiratory Support and Sleep Centre (RSSC). Sixty-four patients (95.5%) were weaned, and 62 patients survived to hospital discharge. NIV was used in weaning 40 patients and in the long term in 25 patients. Median survival was 2.5 years (interquartile range, 0.7 to 4.6 years). One-year, 2-year, and 5-year survival rates were 68%, 54%, and 25%, respectively. Long-term survival was inversely associated with age and LOS in the ICU and the RSSC. The provision of maintenance NIV after weaning was associated with better long-term survival, independent of age and LOS (hazard rate, 0.48; p = 0.03).

CONCLUSIONS

These results demonstrate that a specialist multidisciplinary approach, including the use of NIV, can be successful in weaning most COPD patients from prolonged invasive ventilation. The data also suggest that long-term NIV may improve survival in selected patients.

[Domiciliary ventilation in patients with COPD]

INTRODUCTION

Chronic obstructive pulmonary disease (COPD) has become one of the main indications for domiciliary ventilation, which is usually non-invasive (NIV). This review focuses on the pathophysiology processes and clinical trial data that underlie current guidelines from international societies.

STATE OF THE ART

To date most published studies about domiciliary ventilation in COPD have been short-term and their message is complicated by the presence of significant methodological problems. The two controlled studies of > or =12 months-duration both found that survival was not improved by long-term NIV. Domiciliary ventilation may be considered when long-term oxygen therapy is unsuccessful and when failed with a progressive deterioration in clinical respiratory status with recurrent episodes of acute hypercapnic respiratory failure. A diurnal PaCO(2) > or =55 mmHg (7.3 kPa) is a necessary but not sufficient condition to consider domiciliary ventilation.

CONCLUSION

Domiciliary ventilation should only be initiated in selected patients on the basis of clinical symptoms and exacerbation frequency. Until further characterization of patients who are likely to respond, the response to treatment should be assessed regularly.

Treatments for COPD

The multicomponent nature of chronic obstructive pulmonary disease (COPD) has provided a challenging environment in which to develop successful treatments. A combination of pharmacological and non-pharmacological approaches is used to combat this problem, and an overview of these approaches and their possible future direction is given. Bronchodilators are the mainstay of COPD treatment and can be combined with inhaled corticosteroids for greater efficacy and fewer side effects. A new generation of pharmacotherapeutic agents, most notably phosphodiesterase-4 inhibitors, which are already in the advanced stages of clinical development, and leukotriene B4 inhibitors (in early clinical development), may shape future treatment as further insight is gained into the pathological mechanisms underlying COPD. Non-pharmacologic treatments for COPD include long-term oxygen therapy (LTOT), nasal positive pressure ventilation (nPPV), pulmonary rehabilitation and lung-volume-reduction surgery (LVRS). Apart from smoking cessation, LTOT is the only treatment to date which has been shown to modify survival rates in severe cases; thus its role in COPD is well defined. The roles of nPPV and LVRS are less clear, though recent progress is reported here. In the future, it will be important to establish the precise value of the different treatments available for COPD--evaluating both clinical and physiological endpoints and using the data to more accurately define candidate patients accordingly. The challenge will be to develop this base of knowledge in order to shape future research and allow clinicians to deliver tailored COPD management programmes for the growing number of patients afflicted with this disease.

Randomised crossover study of pressure and volume non-invasive ventilation in chest wall deformity

BACKGROUND

Non-invasive ventilation is an established treatment for chronic respiratory failure due to chest wall deformity. There are few data available to inform the choice between volume and pressure ventilators. The aim of this study was to compare pressure and volume targeted ventilation in terms of diurnal arterial blood gas tensions, lung volumes, hypercapnic ventilatory responses, sleep quality, and effect on daytime function and health status when ventilators were carefully set to provide the same minute ventilation.

METHODS

Thirteen patients with chest wall deformity underwent a 4 week single blind randomised crossover study using the Breas PV403 ventilator in either pressure or volume mode with assessments made at the end of each 4 week period.

RESULTS

Minute ventilation at night was less than that set during the day with greater leakage for both modes of ventilation. There was more leakage with pressure than volume ventilation (13.8 (1.9) v 5.9 (1.0) l/min, p = 0.01). There were no significant differences in sleep quality, daytime arterial blood gas tensions, lung mechanics, ventilatory drive, health status or daytime functioning.

CONCLUSIONS

These data suggest that pressure and volume ventilation are equivalent in terms of the effect on nocturnal and daytime physiology, and resulting daytime function and health status.

Long-term reduction of hyperinflation in stable COPD by non-invasive nocturnal home ventilation

OBJECTIVE

The role of non-invasive positive pressure ventilation (NPPV) in stable COPD with chronic ventilatory failure remains controversial. The impact of long-term home nocturnal NPPV treatment on deflation has not yet been evaluated in detail.

METHODS

Retrospective explorative study of 46 patients with stable COPD undergoing NPPV treatment. Effects of NPPV on body plethysmographic parameters, blood gas tensions and inspiratory muscle function after 6.2 (+/-1.7) and 12.7 (+/-2.1) months of treatment. Further, evaluation of 1-year survival, compliance and ventilation parameters.

RESULTS

One-year survival was 89.1%. The effectiveness of ventilation was proven by a significant reduction in nocturnal and daytime PaCO2. We observed a decrease in the ratio of residual volume (RV) to total lung capacity (TLC) on the average of 5.2+/-9.8% (or 15.2+/-29.7% pred.; P<0.01) at six and 3.9+/-9.0% (or 12.9+/-18.6% pred.; P<0.001) at 12 months. As a consequence, we found significant improvements in inspiratory capacity (IC), vital capacity (VC) and forced expiratory volume in one second (FEV1). For patients with the most severe hyperinflation (RV/TLC>75%), we found a significant positive correlation between inspiratory positive airway pressure (IPAP) and reductions in PaCO2 (r=0.56; P<0.05) and RV/TLC (r=0.50; P<0.05).

CONCLUSIONS

In severe hypercapnic stable COPD long-term nocturnal NPPV can reduce hyperinflation with sustained improved daytime blood gas parameters.

Outcome of Patients With Stable COPD Receiving Controlled Noninvasive Positive Pressure Ventilation Aimed at a Maximal Reduction of Paco2

STUDY OBJECTIVES

The role of noninvasive positive pressure ventilation (NPPV) has been well established in the treatment of acute hypercapnic respiratory failure due to COPD. However, evidence for a sustained improvement in blood gas levels and survival in patients with stable hypercapnic COPD following NPPV is still lacking. There is concern that this might be due to low inspiratory pressures of < 18 cm H2O used in previous studies, which thereby did not achieve a reduction of Pa(CO2). Therefore, the 2-year survival and changes in lung function and blood gas levels were analyzed in patients with stable hypercapnic COPD in whom controlled pressure-limited NPPV was titrated to achieve a maximal improvement in Pa(CO2).

DESIGN

Retrospective study between March 1997 and September 2003.

SETTING

General ward of a university hospital.

PATIENTS

Thirty-four consecutive patients with stable (mean pH 7.40 +/- 0.03) hypercapnic COPD (mean age, 63.4 +/- 9.7 years [+/- SD]; mean body mass index, 28.3 +/- 7.3 kg/m2).

MEASUREMENTS AND RESULTS

Daytime Pa(CO2) during spontaneous breathing decreased by 6.9 +/- 8.0 (95% confidence interval, - 9.9 to - 3.9), from 53.3 +/- 4.8 to 46.4 +/- 7.0 mm Hg (p < 0.001); while daytime Pa(O2) increased by 5.8 +/- 9.4 (95% confidence interval, 2.3 to 9.3), from 51.7 +/- 8.8 to 57.5 +/- 9.3 mm Hg (p = 0.002); and FEV1 increased by 0.14 +/- 0.16 (95% confidence interval, 0.08 to 0.20), from 1.03 +/- 0.54 to 1.17 +/- 0.59 L (p < 0.001) after 2 months of NPPV. This was achieved with mean inspiratory pressures of 27.7 +/- 5.9 cm H2O (range, 17 to 40 cm H2O) at a mean respiratory rate of 20.8 +/- 2.5 breaths/min (range, 14 to 24 breaths/min). The 2-year survival rate was 86%.

CONCLUSIONS

Controlled NPPV using a mean inspiratory pressure of 28 cm H2O is well tolerated over longer periods and can improve blood gas levels and lung function. Prospective, randomized controlled trials of high-intensity NPPV are required to evaluate its role in patients with stable hypercapnic COPD.

[Initiation and management of home mechanical ventilation]

INTRODUCTION

Effective initiation and optimal monitoring of treatment are essential elements for successful home mechanical ventilation (HMV).

STATE OF KNOWLEDGE

Ventilation is best initiated in a hospital setting. There is an enormous range of equipment available but there is little evidence pointing to the superiority of one device over another. Many problems can arise that lead to an interruption in HMV but often these can be resolved simply as discussed in this article.

PERSPECTIVES

Unfortunately a number of pitfalls in management remain, the main one being the absence of accurate data about the sleep of patients on ventilators, which hinders optimal nocturnal management. Another problem is the lack of adaptation of equipment for use by handicapped patients. Finally the transfer of responsibility and workload to home carers including family members with disengagement by the hospital can also be a major milestone.

CONCLUSION

Successful initiation and supervision is the key to effective home mechanical ventilation. Treatment is often abandoned because of pitfalls, mistakes and lack of knowledge. This article proposes means to improve these two important areas.

Assistance ventilatoire à domicile : justifications et contraintes physiopathologiques

INTRODUCTION

Domiciliary assisted ventilation (DAV) may be undertaken invasively or non-invasively. Non-invasive DAV is used for patients suffering from alveolar hypoventilation due to restrictive pathology. Invasive DAV is reserved for "indications of necessity" that is when non-invasive ventilation is contraindicated due to the absence of adequate cough and for alveolar hypoventilation leading to hypercapnoea during spontaneous ventilation.

STATE OF THE ART

The main pathophysiological limitation to non-invasive ventilation is the interference of the glottis. In this mode the glottis imposes a variable resistance to the ventilation delivered. Its behaviour is more predictable during Volume controlled than during pressure controlled ventilation. The control parameters of a Volume controlled ventilator are very different from those used in invasive ventilation during which the respiratory system may be regarded as a single compartment (provided a cuffed tube bypasses the upper airway). In non-invasive DAV: mode VCM, tidal volume 13 mls kg(-1), rate 20 cycles min(-1), insp/exp ratio 1/1.2. In invasive DAV: mode VCM, tidal volume 8-10 mls kg(-1), rate 12 cycles min(-1), insp/exp ratio depending on the pathology 1/2.

PERSPECTIVES

As non-invasive DAV is essentially delivered during sleep the parameters for each patient can be optimised during polysomnography because waking, leading to a partial glottic occlusion, interferes with the ventilation delivered.

CONCLUSIONS

Recent understanding of the way the glottis interferes with mechanical ventilation when delivered non-invasively should lead to a revision of earlier practices based on invasive ventilation.

Non-invasive positive pressure ventilation for treatment of respiratory failure due to exacerbations of chronic obstructive pulmonary disease

BACKGROUND

Non-invasive positive pressure ventilation (NPPV) is being used increasingly in the management of patients admitted to hospital with acute respiratory failure secondary to an exacerbation of chronic obstructive pulmonary disease (COPD).

OBJECTIVES

To determine the efficacy of NPPV in the management of patients with respiratory failure due to an acute exacerbation of COPD.

SEARCH STRATEGY

An initial search was performed using the Cochrane Airways Group trials register and other relevant electronic databases. An updated search was conducted in September 2003 and another in April 2004.

SELECTION CRITERIA

Randomised controlled trials comparing NPPV plus usual medical care (UMC) versus UMC alone were selected. Trials needed to recruit adult patients admitted to hospital with respiratory failure due to an exacerbation of COPD and with PaCO2 > 6 kPa (45 mmHg).

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected articles for inclusion, evaluated methodological quality of the studies and abstracted the data.

MAIN RESULTS

Fourteen studies were included in the review. NPPV resulted in decreased mortality (Relative Risk 0.52; 95%CI 0.35 to 0.76), decreased need for intubation (RR 0.41; 95%CI 0.33 to 0.53), reduction in treatment failure (RR 0.48; 95%CI 0.37 to 0.63), rapid improvement within the first hour in pH (Weight Mean Difference 0.03; 95%CI 0.02 to 0.04), PaCO2 (WMD -0.40 kPa; 95%CI -0.78 to -0.03) and respiratory rate (WMD -3.08 bpm; 95%CI -4.26 to -1.89). In addition, complications associated with treatment (RR 0.38; 95%CI 0.24 to 0.60) and length of hospital stay (WMD -3.24 days; 95%CI -4.42 to -2.06) was also reduced in the NPPV group.

REVIEWERS' CONCLUSIONS

Data from good quality randomised controlled trials show benefit of NPPV as first line intervention as an adjunct therapy to usual medical care in all suitable patients for the management of respiratory failure secondary to an acute exacerbation of COPD. NPPV should be considered early in the course of respiratory failure and before severe acidosis ensues, as a means of reducing the likelihood of endotracheal intubation, treatment failure and mortality.

Non-invasive positive pressure ventilation for treatment of respiratory failure due to exacerbations of chronic obstructive pulmonary disease

BACKGROUND

Non-invasive positive pressure ventilation (NPPV) is being used increasingly in the management of patients admitted to hospital with acute respiratory failure secondary to an exacerbation of chronic obstructive pulmonary disease (COPD).

OBJECTIVES

To determine the efficacy of NPPV in the management of patients with respiratory failure due to an acute exacerbation of COPD.

SEARCH STRATEGY

An initial search was performed using the Cochrane Airways Group trials register and other relevant electronic databases. An updated search was conducted in September 2003.

SELECTION CRITERIA

Randomised controlled trials comparing NPPV plus usual medical care (UMC) versus UMC alone were selected. Trials needed to recruit adult patients admitted to hospital with respiratory failure due to an exacerbation of COPD and with PaCO(2) > 6 kPa (45 mmHg).

DATA COLLECTION AND ANALYSIS

Two reviewers independently selected articles for inclusion, evaluated methodological quality of the studies and abstracted the data.

MAIN RESULTS

Fourteen studies were included in the review. NPPV resulted in decreased mortality (Relative Risk 0.52; 95%CI 0.35, 0.76), decreased need for intubation (RR 0.41; 95%CI 0.33, 0.53), reduction in treatment failure (RR 0.48; 95%CI 0.37, 0.63), rapid improvement within the first hour in pH (Weight Mean Difference 0.03; 95%CI 0.02, 0.04), PaCO(2) (WMD -0.40 kPa; 95%CI -0.78, -0.03) and respiratory rate (WMD -3.08 bpm; 95%CI -4.26, -1.89). In addition, complications associated with treatment (RR 0.38; 95%CI 0.24, 0.60) and length of hospital stay (WMD -3.24 days; 95%CI -4.42, -2.06) was also reduced in the NPPV group.

REVIEWER'S CONCLUSIONS

Data from good quality randomised controlled trials show benefit of NPPV as first line intervention as an adjunct therapy to usual medical care in all suitable patients for the management of respiratory failure secondary to an acute exacerbation of COPD. NPPV should be considered early in the course of respiratory failure and before severe acidosis ensues, as a means of reducing the likelihood of endotracheal intubation, treatment failure and mortality.

Contemporary management of chronic obstructive pulmonary disease: scientific review

CONTEXT

The care of patients with chronic obstructive pulmonary disease (COPD) has changed radically over the past 2 decades, and novel therapies can not only improve the health status of patients with COPD but also modify its natural course.

OBJECTIVE

To systematically review the impact of long-acting bronchodilators, inhaled corticosteroids, nocturnal noninvasive mechanical ventilation, pulmonary rehabilitation, domiciliary oxygen therapy, and disease management programs on clinical outcomes in patients with COPD.

DATA SOURCES

MEDLINE and Cochrane databases were searched to identify all randomized controlled trials and systematic reviews from 1980 to May 2002 evaluating interventions in patients with COPD. We also hand searched bibliographies of relevant articles and contacted experts in the field.

STUDY SELECTION AND DATA EXTRACTION

We included randomized controlled trials that had follow-up of at least 3 months and contained data on at least 1 of these clinical outcomes: health-related quality of life, exacerbations associated with COPD, or death. For pulmonary rehabilitation, we included studies that had a follow-up of at least 6 weeks. Using standard meta-analytic techniques, the effects of interventions were compared with placebo or with usual care. In secondary analyses, the effects of interventions were compared against each other, where possible.

DATA SYNTHESIS

Long-acting beta2-agonists and anticholinergics (tiotropium) reduced exacerbation rates by approximately 20% to 25% (relative risk [RR] for long-acting beta2-agonists, 0.79; 95% CI, 0.69-0.90; RR for tiotropium, 0.74; 95% CI, 0.62-0.89) in patients with moderate to severe COPD. Inhaled corticosteroids also reduced exacerbation rates by a similar amount (RR, 0.76; 95% CI, 0.72-0.80). The beneficial effects were most pronounced in trials enrolling patients with FEV1 between 1 L and 2 L. Combining a long-acting beta2-agonist with an inhaled corticosteroid resulted in an approximate 30% (RR, 0.70; 95% CI, 0.62-0.78) reduction in exacerbations. Pulmonary rehabilitation improved the health status of patients with moderate to severe disease, but no material effect was observed on long-term survival or hospitalization rates. Domiciliary oxygen therapy improved survival by approximately 40% in patients with PaO2 lower than 60 mm Hg, but not in those without hypoxia at rest. The data on disease management programs were heterogeneous, but overall no effect was observed on survival or risk of hospitalization. Noninvasive mechanical ventilation was not associated with improved outcomes.

CONCLUSIONS

A significant body of evidence supports the use of long-acting bronchodilators and inhaled corticosteroids in reducing exacerbations in patients with moderate to severe COPD. Domiciliary oxygen therapy is the only intervention that has been demonstrated to prolong survival, but only in patients with resting hypoxia.

Domiciliary non-invasive ventilation for recurrent acidotic exacerbations of COPD: an economic analysis

BACKGROUND

Patients with chronic obstructive pulmonary disease (COPD) pose a significant burden to healthcare providers with frequent exacerbations necessitating hospital admission. Randomised controlled data exist supporting the use of acute non-invasive ventilation (NIV) in patients with exacerbations of COPD with mild to moderate acidosis. The use of NIV is also described in chronic stable COPD, with evidence suggesting a reduction in hospital admissions and general practitioner care. We present economic data on the impact of domiciliary NIV on the need for admission to hospital and its attendant costs.

METHODS

A cost and consequences analysis of domiciliary NIV based on a before and after case note audit was performed in patients with recurrent acidotic exacerbations of COPD who tolerated and responded well to NIV. The primary outcome measure was the total cost incurred per patient per year from the perspective of the acute hospital. Effectiveness outcomes were total days in hospital and in intensive care.

RESULTS

Thirteen patients were identified. Provision of a home NIV service resulted in a mean (95% CI) saving of pound sterling 8254 (pound sterling 4013 to pound sterling 12,495) (Euro 11,720; Euro 5698 to Euro 17,743) per patient per year. Total days in hospital fell from a mean (SD) of 78 (51) to 25 (25) (p=0.004), number of admissions from 5 (3) to 2 (2) (p=0.007), and ICU days fell from a total of 25 to 4 (p=0.24). Outpatient visits fell from a mean of 5 (3) to 4 (2) (p=0.14).

CONCLUSIONS

This study suggests that domiciliary NIV for a highly selected group of COPD patients with recurrent admissions requiring NIV is effective at reducing admissions and minimises costs from the perspective of the acute hospital. Such evidence is important in obtaining financial support for providing such a service.

Non-invasive positive pressure ventilation (NIPPV) in stable patients with chronic obstructive pulmonary disease (COPD)

While non-invasive positive pressure ventilation (NIPPV) has become an accepted management approach for patients with acute hypercapnia, it remains unclear whether it can also be beneficial in stable chronic obstructive pulmonary disease (COPD) patients with chronic respiratory failure. Randomised controlled trials (RCT) with a maximum duration of 3 months showed contradictory effects in blood gasses, dyspnoea, sleep efficiency and health-related quality of life. On the other hand, several uncontrolled trials did show positive results in patients with hypercapnia. Recently, an RCT compared the combination of NIPPV and long-term oxygen treatment (LTOT) with LTOT alone for a period of 2 years in hypercapnic patients. After this period dyspnoea decreased and health-related quality of life improved in the NIPPV compared to the LTOT group. Reasons for the contradictory results in the different trials are probably patient selection, adequacy of ventilation, and length of ventilation. Therefore, at this moment there is no conclusive evidence that NIPPV should be provided routinely to stable patients with COPD. However, a selected group of patients might have clinical benefits from it. Patients who are clearly hypercapnic, who can tolerate an effective level of ventilatory support, and who get enough time to adjust to the ventilator might show clinical benefits even after 3 months. A trial with ventilatory support in this group of patients can be considered.

Inpatient chronic assisted ventilatory care: a 15-year experience

STUDY OBJECTIVES

Ventilator users who are unable to leave the acute care setting may be transferred to a unit for chronic assisted ventilatory care (CAVC) with the goal of optimizing their level of function. In this report, we summarize the outcomes of all patients admitted to a CAVC unit between 1986 and 2001.

PATIENTS AND METHODS

Fifty patients (24 with neuromuscular disease [NMD], 10 with spinal cord injury [SCI], 7 with thoracic restriction [TR], 7 with COPD, and 2 with parenchymal restriction [PR]) were reviewed. Thirty-eight patients were transferred to the CAVC unit from intensive care, 5 patients were transferred from inpatient respiratory rehabilitation, 4 patients came from home, and 3 patients came from pediatric long-term care. At the time of CAVC unit admission, all patients were receiving mechanical ventilation via a tracheostomy tube.

RESULTS

Ventilator time increased gradually in patients with COPD from 16 h (SD, 5.6) to 22.9 h (SD, 3.0) per day (p < 0.05), and in patients with TR from 18.9 h (SD, 6.1) to 22.9 h (SD, 4.5) [not significant]. Five of the 10 patients with SCI were decannulated. Functional mobility, which decreased in patients with COPD and patients with TR, remained stable in NMD and PR and improved in SCI. Eighteen patients returned home or to an attendant care facility (COPD, n = 1; NMD, n = 10; SCI, n = 5; PR, n = 2); 11 patients died in the CAVC unit (COPD, n = 6; TR, n = 3; NMD, n = 1; SCI, n = 1); and 7 patients were transferred to intensive care, where they died. The average direct cost per patient per diem increased from $252 (Canadian) in 1988 to $335 in 2001.

CONCLUSION

A CAVC unit can provide a safe environment for severely impaired, ventilator-dependent individuals, many of whom (36%) left for a more independent community-based environment. Better outcomes were seen among patients with SCI and NMD than in patients with COPD and TR.

A meta-analysis of nocturnal noninvasive positive pressure ventilation in patients with stable COPD

STUDY OBJECTIVES

The potential benefits of noninvasive positive pressure ventilation (NIPPV) for patients with COPD remains inconclusive, as most studies have included only a small number of patients. We therefore undertook a meta-analysis of randomized controlled trials (RCTs) that compared nocturnal NIPPV with conventional management in patients with COPD and stable respiratory failure.

DESIGN

RCTs were identified from several sources, such as MEDLINE, EMBASE, and CINAHL. In addition, records were identified through hand searching of abstracts from meetings of the American Thoracic Society, the American College of Chest Physicians, and the European Respiratory Society.

PATIENTS

Patients with COPD according to the definition of the American Thoracic Society.

INTERVENTIONS

NIPPV applied via a nasal or facemask for at least 5 h/d for at least 3 weeks. Patients in the actively treated group continued to receive the usual management for COPD. The control group received the same management as the study group but did not receive NIPPV.

MEASUREMENTS AND RESULTS

PaCO(2), PaO(2), 6-min walking distance (6MWD), respiratory muscle function, FEV(1), vital capacity, and sleep efficiency (time asleep as a percentage of total time in bed) were used as outcome measures. The publications were reduced to 10 potentially eligible articles from 164 publications retrieved from computer searches and 8 further abstracts. Four trials were finally included in the meta-analysis. The only outcome for which the confidence intervals excluded zero was maximal inspiratory pressure (PImax). The confidence intervals for the other outcomes included zero. The mean treatment effects for FEV(1) and PImax were small, whereas it was moderate for the 6MWD. Small negative effects were found for the outcomes of vital capacity, PaCO(2), and sleep efficiency.

CONCLUSIONS

This meta-analysis of 3 months of NIPPV in patients with stable COPD showed that ventilatory support did not improve lung function, gas exchange, or sleep efficiency. The high upper limit of the confidence interval for the 6MWD suggested that some people do improve their walking distance. The small overall sample size precluded a clear clinical direction regarding the effects of NIPPV in patients with COPD.

[Noninvasive intermittent self ventilation in chronic respiratory insufficiency]

Corresponding to the two compartments of the respiratory system (lungs and ventilatory pump), two different forms of respiratory insufficiency can be distinguished on a pathophysiologic basis: disturbances of gas exchange with primary oxygenation failure (hypoxemia) due to pulmonary diseases and reduced ventilation of the lungs (hypoventilation) with primary elevated arterial carbon dioxide partial pressure (hypercapnia) and secondary hypoxemia due to disorders of the ventilatory pump. Different methods can be employed in the diagnosis of respiratory insufficiency, e.g., spirometry, blood gas analysis, nocturnal monitoring with capnography, or transcutaneous pCO2 registration and measurement of mouth occluding pressure. Therapeutic measures for respiratory insufficiency are based on two treatment principles: long-term oxygen therapy to improve hypoxemia and noninvasive ventilation therapy to improve hypercapnia and concomitant hypoxemia. The indication for long term ventilation depends on subjective complaints, objective measurement parameters, disease course, and other disease symptoms. The most frequent indications for home mechanical ventilation are diseases with restrictive ventilatory defects, especially chest wall disorders and neuromuscular disorders.

Changing patterns in long-term noninvasive ventilation: a 7-year prospective study in the Geneva Lake area

STUDY OBJECTIVES

To describe a 7-year follow-up (1992 to 2000) of patients who were treated by home nasal positive-pressure ventilation (NPPV) for chronic hypercapnic respiratory failure.

DESIGN

Prospective descriptive study.

SETTING

Two university hospitals and a pulmonary rehabilitation center.

PATIENTS

Two hundred eleven patients with obstructive pulmonary disorders (58 patients) or restrictive pulmonary disorders (post-tuberculosis, 23 patients; neuromuscular diseases [NM], 28 patients; post-poliomyelitis syndrome, 12 patients; kyphoscoliosis [KYPH], 19 patients; obesity-hypoventilation syndrome [OHS], 71 patients) who were treated by long-term NPPV.

INTERVENTION

Annual, elective, standardized medical evaluations.

MEASUREMENTS

Pulmonary function tests, arterial blood gas levels, health status, compliance, survival and probability of pursuing NPPV, and hospitalization rates.

RESULTS

Patients with OHS, NM, and KYPH had the highest probability of pursuing NPPV, while patients with COPD had the lowest values. Overall, the compliance rate was high (noncompliance rate, 15%). As of 1994, COPD and OHS became the most frequent indications for NPPV, increasing regularly, while other indications remained stable. The use of pressure-cycled ventilators progressively replaced that of volume-cycled ventilators in most indications. Hospitalization rates decreased in all groups after initiating NPPV, when compared with the year before NPPV, for up to 2 years in COPD patients, and 5 years in non-COPD patients.

CONCLUSION

Major changes in patient selection for NPPV occurred during the study period with a marked increase in COPD and OHS. The shift toward less expensive pressure-cycled ventilators and the decrease in hospitalizations after initiating NPPV have had positive impacts on the cost-effectiveness of NPPV in patients with chronic respiratory failure.

Physiologic evaluation of 4 weeks of nocturnal nasal positive pressure ventilation in stable hypercapnic patients with chronic obstructive pulmonary disease

BACKGROUND

The long-term daily use of noninvasive mechanical ventilation (NIMV) to treat chronic respiratory failure in chronic obstructive pulmonary disease (COPD) patients is not widely recommended, partly because of a lack of clear clinical results and partly because the physiological mechanisms by which the daily application of NIMV would be helpful in these patients have not yet been clarified.

OBJECTIVES

We designed a physiological study in order to assess the effects of supervised long-term NIMV on gas exchange, respiratory muscle function, pulmonary mechanics and to ascertain the possible effect of the treatment in responders and nonresponders.

METHODS

Fourteen consecutive inpatients with stable hypercapnic COPD (pH = 7.37 +/- 0.01; PaCO(2) = 56.73 +/- 6.48 mm Hg) underwent 4 weeks of nocturnal NIMV delivered with a bilevel ventilator 'physiologically' set to reduce tidal transdiaphragmatic pressure (Pdi) by at least 50% and the amount of dynamic intrinsic positive end-expiratory pressure by 70%. Various measurements were compared with those obtained in a control group of consecutive patients with comparable baseline characteristics who refused NIMV and underwent breathing exercises for the same period of time.

RESULTS

By the end of the 4 weeks NIMV had induced a slight but significant (p < 0.01) reduction in resting PaCO(2) (53.78 +/- 5.64 mm Hg) associated with a decrease in the pressure time product of the diaphragm per minute (from 172 +/- 60 to 136 +/- 61 cm H(2)O/l/s; p < 0.05). This latter value was primarily due to a significant shortening of the inspiratory duty cycle, while Pdi and lung mechanics were not modified. Eight of the 13 NIMV-treated patients (1 dropped out for nonmedical reasons) had a clear reduction in PaCO(2) (>3 mm Hg or >5% from enrollment) and were classified as responders. The acute reduction in PaCO(2) during the first trial with NIMV resulted to be a strong index of the final response. The subgroup of responders had a significantly increased maximal Pdi (from 41 +/- 19 to 49 +/- 23 cm H(2)O, p < 0.05) and an enhanced ability of the ventilatory pump to clear CO(2) (9.7 +/- 3.4 vs. 7.2 +/- 2.9 cm H(2)O x s/min; p < 0.01). No significant changes were observed in the control group.

CONCLUSIONS

These results suggest that in a remarkable and identifyable proportion of patients with stable hypercapnic COPD, nocturnal NIMV may decrease resting PaCO(2), reraising the role of chronically supporting the respiratory pump.

Ventilation of patients with asthma and chronic obstructive pulmonary disease

Ventilatory intervention is often life-saving when patients with asthma or chronic obstructive pulmonary disease (COPD) experience acute respiratory compromise. Although both noninvasive and invasive ventilation methods may be viable initial choices, which is better depends upon the severity of illness, the rapidity of response, coexisting disease, and capacity of the medical environment. In addition, noninvasive ventilation often relieves dyspnea and hypoxemia in patients with stable severe COPD. On the basis of current evidence, the general principles of ventilatory management common to patients with acutely exacerbated asthma/COPD are these: noninvasive ventilation is suitable for a relatively simple condition, but invasive ventilation is usually required in patients with more complex or more severe disease. It is crucial to provide controlled hypoventilation, longer expiratory time, and titrated extrinsic positive end-expiratory pressure to avoid dynamic hyperinflation and its attendant consequences. Controlled sedation helps achieve synchrony of triggering, power, and breath timing between patient and ventilator. When feasible, noninvasive ventilation often facilitates the weaning of ventilator-dependent patients with COPD and shortens the patient's stay in the intensive care unit.

Nocturnal non-invasive positive pressure ventilation for stable chronic obstructive pulmonary disease

BACKGROUND

Nocturnal non-invasive positive pressure ventilation (NIPPV) might be beneficial in stable hypercapnic patients with chronic obstructive pulmonary disease (COPD). However, evidence remains equivocal as conflicting results have been published.

OBJECTIVES

To determine the effect of nocturnal non-invasive positive pressure ventilation via nasal mask or face mask in patients with COPD.

SEARCH STRATEGY

An initial search was carried out using the Cochrane Airways Group COPD RCT register using the search terms: (nasal ventilat* OR positive pressure OR NIPPV). An additional search was done by hand searching of abstracts from meetings of the American Thoracic Society, British Thoracic Society and European Respiratory Society.

SELECTION CRITERIA

Randomised controlled trials in stable patients with COPD that compared nocturnal non-invasive positive pressure ventilation plus standard therapy with standard therapy alone.

DATA COLLECTION AND ANALYSIS

Data extraction was performed by two independent reviewers.

MAIN RESULTS

The only outcome for which the 95% confidence interval excluded zero was PI max. The 95% confidence interval (CI) of the other outcomes included zero. These included FEV1,FVC, PaCO2, sleep efficiency and 6-minute walking distance (6MWD). The mean effect on 6MWD was modest at 27.5 m, but the 95% CI were wide (-28.1, 81.8 m) suggesting that some patients had a big improvement. Such patients could not be identified a priori.

REVIEWER'S CONCLUSIONS

Nocturnal NIPPV for at least 3 months in hypercapnic patients with stable COPD had no consistent clinically or statistically significant effect on lung function, gas exchange, respiratory muscle strength, sleep efficiency or exercise tolerance. However, the small sample sizes of these studies precludes a definite conclusion regarding the effects of NIPPV in COPD.

Noninvasive ventilation and obstructive lung diseases

The key role of noninvasive positive pressure ventilation (NPPV) is well documented in chronic obstructive pulmonary disease (COPD) patients with acute respiratory failure (ARF) since it may avoid endotrachal intubation in >50% of cases when used as the initial treatment. However, currently only minimal data is available to assess usefulness of NPPV in COPD patients on a long-term basis. Even if such studies are difficult to manage, there is clearly a need for prospective studies comparing long-term oxygen therapy (LTOT) and NPPV in the most severe COPD in a large amount of patients and on a real long-term basis of several years. Two randomized prospective studies are being completed in Europe and the first preliminary results show that NPPV is associated with a reduction of hospitalization for chronic respiratory failure decompensation. The main beneficial effect of long-term mechanical ventilation in COPD patients with chronic respiratory failure implies a correction of nocturnal hypoventilation that could persist beyond the ventilation period because of a temporary improvement in carbon dioxide sensitivity that is often blunted in these patients. A synthesis from the literature suggest to consider NPPV for severe COPD patients who present with chronic hypoxia and hypercapnia and develop an unstable respiratory condition. Instability may be appreciated on a clinical basis and confirmed by a progressive worsening of arterial blood gas tensions, leading to frequent cardiorespiratory decompensations with ominous ARF episodes. NPPV should also be considered after an ARF episode successfully treated by noninvasive ventilation but with the impossibility to wean the patient from the ventilator. Thus, noninvasive positive pressure ventilation could be proposed as a preventive treatment in severe chronic obstructive pulmonary disease patients with unstable respiratory condition associated with fluctuating hypercapnia before, during and after an acute respiratory failure episode, avoiding the need for a tracheotomy. Adjunction of noninvasive ventilation to exercise rehabilitation is under evaluation.