Noninvasive versus conventional ventilation to treat hypercapnic encephalopathy in chronic obstructive pulmonary disease

Objective We recently reported a high success rate using noninvasive positive pressure ventilation (NPPV) to treat COPD exacerbations with hypercapnic encephalopathy. This study compared the hospital outcomes of NPPV vs. conventional mechanical ventilation (CMV) in COPD exacerbations with moderate to severe hypercapnic encephalopathy, defined by a Kelly score of 3 or higher. Design and setting A 3-year prospective matched case-control study in a respiratory semi-intensive care unit (RSICU) and intensive care unit (ICU). Patients and participants From 103 consecutive patients the study included 20 undergoing NPPV and 20 CMV, matched for age, simplified acute physiology score II, and baseline arterial blood gases. Measurements and results ABG significantly improved in both groups after 2 h. The rate of complications was lower in the NPPV group than in the CMV group due to fewer cases of nosocomial pneumonia and sepsis. In-hospital mortality, 1-year mortality, and tracheostomy rates were similar in the two groups. Fewer patients remained on ventilation after 30 days in NPPV group. The NPPV group showed a shorter duration of ventilation. Conclusions In COPD exacerbations with moderate to severe hypercapnic encephalopathy, the use of NPPV performed by an experienced team compared to CMV leads to similar short and long-term survivals with a reduced nosocomial infection rate and duration of ventilation.     

Early fiberoptic bronchoscopy during non-invasive ventilation in patients with decompensated chronic obstructive pulmonary disease due to community-acquired-pneumonia

Introduction  

Inefficient clearance of copious respiratory secretion is a cause of non-invasive positive pressure ventilation (NPPV) failure, especially in chronic respiratory patients with community-acquired-pneumonia (CAP) and impaired consciousness. We postulated that in such a clinical scenario, when intubation and conventional mechanical ventilation (CMV) are strongly recommended, the suction of secretions with fiberoptic bronchoscopy (FBO) may increase the chance of NPPV success. The objective of this pilot study was, firstly, to verify the safety and effectiveness of early FBO during NPPV and, secondly, to compare the hospital outcomes of this strategy versus a CMV-based strategy in patients with decompensated chronic obstructive pulmonary disease (COPD) due to CAP who are not appropriate candidates for NPPV because of inefficient mucous clearance and hypercapnic encephalopathy (HE).     

Causes of failure of noninvasive mechanical ventilation

With selected patients noninvasive positive-pressure ventilation (NPPV) can obviate endotracheal intubation and thus avoid the airway trauma and infection associated with intubation. With patients who can cooperate, NPPV is the first-line treatment for mild-to-severe acute hypercapnic respiratory failure. NPPV is also used for hypercapnic ventilatory failure and to assist weaning from mechanical ventilation, by allowing earlier extubation. Some patients do not obtain adequate ventilation with NPPV and therefore require intubation. Also, some patients will initially benefit from NPPV (for one-to-several days) but will then deteriorate and require intubation. It is not always apparent which patients will initially benefit from NPPV, so researchers have been looking for variables that predict NPPV success/failure. The reported NPPV failure rate is 5-40%, so the necessary staff and equipment for prompt intubation should be readily available. Absolute contraindications to NPPV are: cardiac or respiratory arrest; nonrespiratory organ failure (eg, severe encephalopathy, severe gastrointestinal bleeding, hemodynamic instability with or without unstable cardiac angina); facial surgery or trauma; upper-airway obstruction; inability to protect the airway and/or high risk of aspiration; and inability to clear secretions. The NPPV training and experience of the clinician team partly determines whether the patient will succeed with NPPV or, instead, require intubation. Greater clinician-team NPPV experience and expertise are associated with a higher percentage of patients succeeding on NPPV and with NPPV success with sicker patients (than will succeed with a less-experienced clinician team). With patients suffering hypercapnic respiratory failure the best NPPV success/failure predictor is the degree of acidosis/acidemia (pH and P(aCO(2)) at admission and after 1 hour on NPPV), whereas mental status and severity of illness are less reliable predictors. With patients suffering hypoxic respiratory failure the likelihood of NPPV success seems to be related to the underlying disease rather than to the degree of hypoxia. For example, the presence of acute respiratory distress syndrome or community-acquired pneumonia portends NPPV failure, as does lack of oxygenation improvement after an hour on NPPV. All the proposed NPPV success/failure predictors should be used cautiously and need further study. We predict that further study and team experience will improve the NPPV success rate and allow successful NPPV-treatment of sicker patients.     

Long-term oxygen therapy vs long-term ventilatory assistance

The use of positive-pressure nasal ventilation in combination with LTOT in stable COPD patients with hypercapnic respiratory failure controls hypoventilation and improves daytime ABGs, sleep, and quality of life. Nasal ventilation in COPD is unlikely to produce benefit unless used with supplemental oxygen therapy at night. The patients who show the greatest reduction in overnight PaCO2 with ventilation are the patients most likely to benefit from long-term ventilatory support. Although there is now evidence for short-term benefit from NPPV in hypercapnic COPD, large multicenter studies with survival, exacerbations, and hospital admissions as the primary end points are required to evaluate longer-term effects of this potentially important intervention.     

The evidence for noninvasive positive-pressure ventilation in the care of patients in acute respiratory failure: a systematic review of the literature

Noninvasive positive-pressure ventilation (NPPV) is increasingly being used in the care of patients suffering acute respiratory failure. High-level evidence supports the use of NPPV to treat exacerbation of chronic obstructive pulmonary disease (COPD). NPPV has also been successfully used with selected patients suffering acute hypoxemic respiratory failure and to allow earlier extubation of mechanically ventilated COPD patients. The evidence for NPPV for acute cardiogenic pulmonary edema is inconclusive. With selected patients NPPV decreases the rate of intubation, mortality, and nosocomial pneumonia. Predictors of NPPV failure include greater severity of illness, lower level of consciousness, lower pH, more air leak around the patient-mask interface, greater quantity of secretions, poor initial response to NPPV, and the presence of pneumonia. NPPV obviates intubation in > 50% of appropriately selected patients. Both nasal and oronasal interfaces have been successfully used to apply NPPV, but the oronasal interface is often preferred for acute respiratory failure. Any ventilator and ventilator mode can be used to apply NPPV, but portable pressure ventilators and pressure-support mode are most commonly used. Inhaled bronchodilators can be administered during NPPV, and NPPV can be delivered with helium-oxygen mixture. Institution-specific practice guidelines may be useful to improve NPPV success.     

Noninvasive ventilation for chronic obstructive pulmonary disease

Noninvasive positive-pressure ventilation (NPPV) should be considered a standard of care to treat COPD exacerbations in selected patients, because NPPV markedly reduces the need for intubation and improves outcomes, including lowering complication and mortality rates and shortening hospital stay. Weaker evidence indicates that NPPV is beneficial for COPD patients suffering respiratory failure precipitated by superimposed pneumonia or postoperative complications, to allow earlier extubation, to avoid re-intubation in patients who fail extubation, or to assist do-not-intubate patients. NPPV patient-selection guidelines help to identify patients who need ventilatory assistance and exclude patients who are too ill to safely use NPPV. Predictors of success with NPPV for COPD exacerbations have been identified and include patient cooperativeness, ability to protect the airway, acuteness of illness not too severe, and a good initial response (within first 1-2 h of NPPV). In applying NPPV, the clinician must pay attention to patient comfort, mask fit and air leak, patient-ventilator synchrony, sternocleidomastoid muscle activity, vital signs, hours of NPPV use, problems with patient adaptation to NPPV (eg, nasal congestion, dryness, gastric insufflation, conjunctival irritation, inability to sleep), symptoms (eg, dyspnea, fatigue, morning headache, hypersomnolence), and gas exchange while awake and asleep. For severe stable COPD, preliminary evidence suggests that NPPV might improve daytime and nocturnal gas exchange, increase sleep duration, improve quality of life, and possibly reduce the need for hospitalization, but further study is needed. There is consensus, but without strong supportive evidence, that COPD patients who have substantial daytime hypercapnia and superimposed nocturnal hypoventilation are the most likely to benefit from NPPV. Adherence to NPPV is problematic among patients with severe stable COPD.     

Noninvasive positive pressure ventilation reverses acute respiratory failure in select "do-not-intubate" patients

OBJECTIVE: To determine the outcome from the use of noninvasive positive pressure ventilation (NPPV) in "do-not-intubate" (DNI) patients in acute respiratory failure. DESIGN: Prospective observational study. SETTING: University-affiliated large medical center. PATIENTS: All patients with DNI status who received NPPV for a 1-yr period. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Demographic, physiologic, and laboratory data were collected before initiation, 2 hrs after initiation, and each morning and evening for as long as NPPV was provided. Data were recorded on 137 episodes of acute respiratory failure in 131 DNI patients. Hospital mortality rate was 37.5% in 24 patients with an exacerbation of chronic obstructive pulmonary disease (COPD), 39% in 28 patients with acute cardiogenic pulmonary edema, 68% in nine patients with non-COPD hypercapnic ventilatory failure, 77% in 13 post-extubation respiratory failure patients, and 86% in 57 patients with hypoxemic respiratory failure. Advanced cancer was present in 40 patients and was associated with increased risk of death (85% mortality rate, p = .002). A score based on the Simplified Acute Physiology Score (SAPS) II and serum albumin level calculated before NPPV was predictive of hospital outcome. CONCLUSIONS: NPPV is successful in reversing acute respiratory failure and preventing hospital mortality in DNI patients with COPD and cardiogenic pulmonary edema but not in patients with post-extubation failure, hypoxemic respiratory failure, or end-stage cancer. An easy-to-calculate score combining SAPS II and serum albumin level is a good prediction of outcome in DNI patients receiving NPPV.     

Overview of reviews: Mechanical interventions for the treatment and management of chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is characterized by a progressive and non‐reversible airflow limitation and symptoms of breathlessness, sputum production and cough. COPD is the fourth most common cause of mortality worldwide and represents a significant social and economic burden. As such, effective strategies that might be employed to treat COPD and manage symptoms need to be investigated. This overview aimed to summarize the existing evidence available in the Cochrane Library regarding the use of mechanical interventions used for the treatment and management of COPD. Systematic reviews that included adult participants with diagnosed COPD who received a mechanical intervention were included. Five reviews were included, and due to the heterogeneity of these reviews, direct and indirect comparisons of the effects of the intervention were not possible. Instead, data of the effectiveness of each intervention were extracted and summarized in tables and discussed as a narrative summary. Interventions included non‐invasive positive pressure ventilation (NPPV), positive airway pressure (PEP) devices and neuromuscular electrical stimulation (NMES). Evidence regarding the effectiveness of NPPV was limited, and available data do not support the use of NPPV for patients with stable COPD. NPPV might, however, be of benefit as a weaning strategy for intubated patients and for patients experiencing respiratory failure; however, more research is required. Although PEP devices are considered as a safe airway clearance technique, data do not reveal a clear clinical benefit to their use. NMES is also regarded as safe for patients with COPD, and might also be beneficial in improving exercise tolerance and improving quality of life for patients with COPD.     

Effectiveness of non-invasive positive pressure ventilation differs between decompensated chronic restrictive and obstructive pulmonary disease patients

OBJECTIVE: To compare the efficiency of non-invasive positive pressure ventilation (NPPV) in decompensated patients with either chronic obstructive pulmonary disease (COPD) or chronic restrictive pulmonary disease. DESIGN: Retrospective study. SETTING: A 17-bed intensive care unit in a university teaching hospital. SETTING: Sixty-four patients with COPD (age: 70+/-13 years, sex ratio: 37 male to 27 female patients, forced expiratory volume in 1 s: 31+/-13% predicted) and 20 patients with chronic restrictive pulmonary disease (age: 75+/-9 years, sex ratio: 9 male to 11 female patients, total lung capacity: 57+/-17% predicted) consecutively treated with NPPV (facial mask, pressure support ventilation (PSV) +/- PEEP) for acute respiratory failure. MEASUREMENTS AND RESULTS: There were no statistically significant differences between COPD and patients with chronic restrictive pulmonary disease in terms of cause of exacerbation, use of oxygen therapy or NPPV at home, severity of acute respiratory failure (ARF), mean delay from intensive care admission to initiation of NPPV and total duration of NPPV. Patients with chronic restrictive pulmonary disease had a lower success rate on NPPV (without need of tracheal intubation) than COPD (35% vs 67%, p=0.01). Causes of NPPV failure were not different between COPD and patients with restrictive disease. After 12 h of NPPV, restrictive patients who succeeded with NPPV had similar respiratory rate, minute ventilation and arterial blood gas to COPD patients. At the 3rd and 12th h of NPPV, improvements in pH and PaCO(2) were predictive of NPPV success in COPD, but not in restrictive patients. CONCLUSION: The results of this retrospective study suggest that the effectiveness of NPPV for acute decompensation is less in patients with chronic restrictive pulmonary disease as compared to COPD.     

Missed opportunities for noninvasive positive pressure ventilation: a utilization review

BACKGROUND: Although noninvasive positive pressure ventilation (NPPV) improves outcomes in patients who have acute respiratory failure due to chronic obstructive pulmonary disease (COPD) or congestive heart failure (CHF), it may be underutilized outside the controlled trial setting. PURPOSE: The purpose of this study is to determine the proportion of patients who met criteria for a trial of NPPV but were emergently intubated and mechanically ventilated without receiving a trial of NPPV. METHODS: We retrospectively reviewed charts of patients who were intubated and ventilated or who received NPPV on admission to one intensive care unit and who had an intensive care unit admitting diagnosis of either exacerbation of COPD or CHF during the period from November 1998 to July 2003. RESULTS: Of the 243 patients who had an admitting diagnosis of COPD or CHF, 59 (24.3%) met explicit criteria for a trial of NPPV. Only 20 (33.9%) of 59 had a trial of NPPV. The remaining 39 (66%) of 59 did not receive a trial of NPPV and were intubated. INTERPRETATION: Nearly two thirds of patients who appeared to meet criteria for NPPV did not receive a trial of this intervention. There is an opportunity to improve the use of NPPV in these patients. Systematic knowledge translation strategies such as guideline implementation and interactive educational interventions may optimize the appropriate use of NPPV.     

Long term oxygen therapy and mechanical ventilation for patients with COPD

Non-drug treatments such as long term oxygen therapy (LTOT) and non-invasive positive pressure ventilation (NPPV) are thought important for patients with chronic obstructive pulmonary disease (COPD). It is reported that LTOT can improve the prognosis of patients with COPD, particularly who have severe respiratory failure. NPPV attracted attention to avoid endotracheal intubation and high efficacy in patients with acute exacerbation of COPD. In chronic phase of COPD, NPPV may improve the quality of life in patients with hypercapnia, selected carefully.     

Noninvasive positive pressure ventilation in patients with COPD]

There is sufficient clinical evidence to justify the use of long-term NPPV in selected patients with COPD who have daytime hypercapnia complicated by nocturnal hypoventilation that can be reversed with NPPV. In those patients, NPPV can improve their arterial blood gases and symptoms, reduce their hospital stay, and increase their QOL. In selected COPD patients with acute exacerbation, NPPV can decrease rates of tracheal intubation leading to reduced mortality. For maximal effectiveness, NPPV must be used early in the course of the respiratory failure (less severe levels of acidosis).     

Short-term effect of controlled instead of assisted noninvasive ventilation in chronic respiratory failure due to chronic obstructive pulmonary disease

BACKGROUND: Noninvasive positive-pressure ventilation (NPPV) unloads respiratory muscles. Spontaneous-breathing ventilation modes require patient effort to trigger the ventilator, whereas controlled modes potentially economize on patient triggering effort and thus achieve more complete respiratory muscle rest. Data on controlled NPPV have not been published to date. We hypothesize that controlled ventilation is feasible in patients with hypercapnic chronic obstructive pulmonary disease. METHODS: We measured blood gas values, respiratory muscle strength, spontaneous breathing pattern, and lung function before and after a 3-month period of NPPV in 305 patients (213 male, mean +/- SD age 61.3 +/- 8.6 y). The subjects used a controlled NPPV mode when they could tolerate it. RESULTS: Ninety-one percent of the patients were able to adapt to a controlled NPPV mode. In those patients, daytime P(CO(2)) decreased from 56.7 +/- 7.5 mm Hg to 47.5 +/- 6.6 mm Hg (p < 0.001) and P(O(2)) increased from 49.2 +/- 8.8 mm Hg to 56.2 +/- 8.5 mm Hg (p < 0.001). Their mean maximum inspiratory pressure increased from 42.3 +/- 16.9 cm H(2)O to 48.4 +/- 18.0 cm H(2)O (p < 0.001). Their mean vital capacity increased from 1.89 +/- 0.62 L to 1.99 +/- 0.67 L (p = 0.004). And their spontaneous breathing pattern became less rapid and shallow. CONCLUSIONS: Controlled NPPV is feasible in patients with hypercapnic chronic obstructive pulmonary disease. We observed improved blood gas values, lung function, and inspiratory muscle strength.     

Health technology assessment in the ICU: noninvasive positive pressure ventilation for acute respiratory failure

Critical care practitioners have a number of health-related technologies at our disposal to provide the best possible care for our critically ill patients. Although certain technologies may improve outcomes in the intensive care unit (ICU), many technologies are disseminated without rigorous evaluation. Health technology assessment (HTA) in critical care is a complex and dynamic process, which is a powerful tool to assess a health technology for its initial use or continued application in the ICU. This article applies an HTA framework to the use of noninvasive positive pressure ventilation (NPPV) for patients with acute respiratory failure (ARF). The strongest evidence to date supports the use of NPPV in patients with ARF caused by exacerbations of chronic obstructive pulmonary disease (COPD); the benefit for patients with acute nonhypercarbic, hypoxemic respiratory failure is less clear. The success of NPPV technology depends on operator education and experience. The cost effectiveness of NPPV has been evaluated in patients with ARF caused by COPD, and cost reduction is attributed to the prevention of ventilator-associated pneumonia by avoiding endotracheal intubation. An HTA framework can help health care practitioners make important decisions regarding the acquisition of new technologies and the evaluation of current technologies. Careful evaluation of health technologies in the ICU should be an ongoing priority.     

Noninvasive positive-pressure ventilation in patients with milder chronic obstructive pulmonary disease exacerbations: a randomized controlled trial

OBJECTIVES: To determine the effect of the addition of noninvasive positive-pressure ventilation (NPPV) to standard medical therapy on length of hospital stay among patients presenting with mild exacerbations of chronic obstructive pulmonary disease (COPD) requiring hospitalization. DESIGN: Randomized controlled unblinded study with concealed allocation. SETTING: Respiratory ward of a single-center, academic, tertiary-care hospital. PARTICIPANTS: Patients with a prior history of COPD who presented with a recent onset of shortness of breath and a pH of > 7.30 were eligible for inclusion in the study. INTERVENTIONS: NPPV daily for 3 days for intervals of 8, 6, and 4 hours, respectively, plus standard therapy, versus standard therapy alone. MEASUREMENTS: Borg dyspnea index at baseline, 1 hour, and daily. Length of hospital stay, endotracheal intubation, hospital survival. RESULTS: We found that NPPV was generally poorly tolerated, with only 12 of 25 patients wearing it for the prescribed 3 days. With the exception of a decrease in dyspnea at 1 hour and 2 days, significant between-group differences were not seen for any measured variable. CONCLUSIONS: The effectiveness and cost-effectiveness of the addition of NPPV to standard therapy in milder COPD exacerbations remains unclear. P(aCO(2)) related to this increased WOB that requires intervention with some form of assisted ventilation. All patients developing an exacerbation of COPD that requires hospitalization have an increased WOB and, we hypothesize, potentially develop some degree of associated respiratory muscle fatigue. We further hypothesize that adding intermittent NPPV during the initial days of hospital stay would afford respiratory muscle rest for patients with milder COPD exacerbations and that this rest would allow these patients to recover more quickly and to be discharged home earlier. The objective of this trial was to determine whether the addition of NPPV to standard therapy during the first 3 days of admission in milder COPD exacerbations could decrease length of hospital stay.     

慢性阻塞性肺疾病急性加重患者的机械通气指南(2007)

慢性阻塞性肺疾病（COPD）是一种常见的慢性呼吸系统疾病，患病人数多，病死率高，严重影响患者的劳动能力和生活质量。2002年世界卫生组织（WHO）公布的资料显示，COPD是目前世界上死亡的第五位病因，预计到2020年，COPD将成为第三位死亡病因。COPD急性加重（AECOPD）合并呼吸衰竭（呼衰）是导致COPD患者住院最重要的原因，加强对AECOPD的防治，特别是提高机械通气技术的应用水平，对提高AECOPD合并呼衰的抢救成功率具有重要意义。     

Noninvasive positive pressure ventilation in the setting of severe, acute exacerbations of chronic obstructive pulmonary disease: more effective and less expensive

OBJECTIVE: The use of noninvasive ventilation for patients with acute respiratory failure has become increasingly popular over the last decade. Although the literature provides good evidence for the effectiveness of noninvasive ventilation in addition to standard therapy compared with standard therapy alone in patients with chronic obstructive pulmonary disease (avoiding intubation and improving hospital mortality), the associated costs have not been rigorously measured. Adding noninvasive positive pressure ventilation (NPPV) to standard therapy in the setting of a severe, acute exacerbation of chronic obstructive pulmonary disease (COPD) in patients with respiratory acidosis who are at high risk of requiring endotracheal intubation is both more effective and less expensive. DESIGN: Economic evaluation based on theoretical model. SETTING: This analysis base case was modeled for a tertiary care, teaching hospital. PATIENTS OR OTHER PARTICIPANTS: Carefully selected patients with severe exacerbations of COPD. INTERVENTION: The two alternative therapies compared were standard therapy (oxygen, bronchodilators, steroids, and antibiotics) and standard therapy plus NPPV. MEASUREMENTS AND MAIN RESULTS: As the hypothesis was dominance, the main outcomes modeled and calculated were costs, mortality rate, and rates of intubation between the two interventions. To determine clinical effectiveness, we used a meta-analysis of randomized trials evaluating the impact of NPPV on hospital survival. A decision tree was constructed and probabilities were applied at each chance node using research evidence and a comprehensive regional database. To provide data for this economic evaluation, MEDLINE literature searches were conducted. Bibliographies of relevant articles were reviewed, as were personal files. To estimate the costs of the alternative therapeutic approaches, eight types of hospitalization days were costed using the London Health Sciences Center costing data. Sensitivity analyses were performed, varying all assumptions made. The meta-analysis yielded an odds ratio for hospital mortality in the NPPV arm, compared with standard therapy, of 0.22 (95% confidence interval, 0.10-0.66). By using baseline case assumptions, we found a cost savings of $3,244 (1996, Canadian), per patient admission, if NPPV were adopted in favor of standard therapy. These findings present a scenario of clear dominance for treatment with NPPV. Sensitivity analyses did not alter the results appreciably. CONCLUSIONS: We conclude that from a hospital's perspective, NPPV and standard therapy for carefully selected patients with acute, severe exacerbations of COPD are more effective and less expensive than standard therapy alone.     

Use of noninvasive positive-pressure ventilation on the regular hospital ward: experience and correlates of success

BACKGROUND: Though noninvasive positive-pressure ventilation (NPPV) is efficacious in treating patients with exacerbations of chronic obstructive pulmonary disease, little attention has been given to the optimal venue in which to provide NPPV. The aim of this prospective observational study was to assess the outcomes of NPPV initiated for acute respiratory failure on the regular in-patient ward. METHODS: Starting in May 2004, all patients started on NPPV for acute respiratory failure on regular nursing floors of the Cleveland Clinic Hospital were identified. Patients were divided into 2 groups: do-not-intubate (DNI) and non-DNI. NPPV failure was defined as the need to transfer the patient to the intensive care unit (ICU). RESULTS: Seventy-six patients were enrolled. The most common cause of acute respiratory failure was exacerbation of chronic obstructive pulmonary disease (41%), followed by pulmonary edema, pneumonia, obesity-hypoventilation, and neuromuscular illness. Of the 62 non-DNI patients, 19 (31%) failed NPPV on the regular ward and required transfer to the ICU. Variables associated with NPPV failure were amount of secretions (p = 0.04), etiology of respiratory failure (pneumonia was associated with the highest failure rate, p = 0.015), and infiltrate on the chest radiograph (p = 0.036). Seven of the 14 (50%) DNI patients died during hospitalization. CONCLUSIONS: Results of this observational study show that noninvasive positive-pressure ventilation is frequently used on the regular hospital ward and that the success rate is similar to that reported in series in which NPPV is used in the ICU.     

Physiological effects of noninvasive positive ventilation during acute moderate hypercapnic respiratory insufficiency in children

Introduction  A prospective physiological study was performed in 12 paediatric patients with acute moderate hypercapnic respiratory insufficiency to assess the ability of noninvasive positive pressure ventilation (NPPV) to unload the respiratory muscles and improve gas exchange. Materials and methods  Breathing pattern, gas exchange, and inspiratory muscle effort were measured during spontaneous breathing and NPPV. Results  NPPV was associated with a significant improvement in breathing pattern, gas exchange and respiratory muscle output. Tidal volume and minute ventilation increased by 33 and 17%, and oesophageal and diaphragmatic pressure time product decreased by 49 and 56%, respectively. This improvement in alveolar ventilation translated into a reduction in mean partial pressure in carbon dioxide from 48 to 40 mmHg (P = 0.01) and in respiratory rate from 48 to 41 breaths/min (P = 0.01). No difference between a clinical setting and a physiological setting of NPPV was observed. In conclusion, this study shows that NPPV is able to unload the respiratory muscles and improve clinical outcome in young patients admitted to the paediatric intensive care unit for acute moderate hypercapnic respiratory insufficiency. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Ventilatory assist therapy

NPPV has been shown to improve arterial blood gas values, prevent symptoms resulting from alveolar hypoventilation, and decrease hospitalization in patients with chronic respiratory failure with COPD. Regarding acute exacerbation of COPD, the utility of NPPV has been established so NPPV will be regarded first-line therapy as ventilatory assist therapy. On the other hand, with respect to chronic stable COPD, the utility of NPPV isn' t established yet. However NPPV cases have been increasing rapidly in these years, as new home respiratory care technique. From now on, we have to evaluate the objective utility of NPPV from the standpoint of evidence.