Noninvasive vs. conventional mechanical ventilation in patients with chronic obstructive pulmonary disease after failure of medical treatment in the ward: a randomized trial

Factors predicting successful noninvasive ventilation in acute lung injury

PURPOSE

Noninvasive ventilation (NIV) has been successfully used to treat various forms of acute respiratory failure. It remains unclear whether NIV has potential as an effective therapeutic method in patients with acute lung injury (ALI). The aims of this study were to determine factors predicting the need for endotracheal intubation in ALI patients treated with NIV, and to promote the selection of patients suitable for NIV.

METHODS

We conducted a retrospective study of all patients admitted to the intensive care unit (ICU) of the Nippon Medical School Hospital from 2000 to 2006 with a diagnosis of ALI, in whom NIV was initiated.

RESULTS

A total of 47 patients with ALI received NIV, and 33 patients (70%) successfully avoided endotracheal intubation. Patients who required endotracheal intubation had a significantly higher Acute Physiology and Chronic Health Evaluation (APACHE) II score and a significantly higher Simplified Acute Physiology Score (SAPS) II, and a significantly lower arterial pH. The respiratory rate decreased significantly within 1 h of starting NIV only in patients successfully treated with NIV. An APACHE II score of more than 17 (P = 0.022) and a respiratory rate of more than 25 breaths x min(-1) after 1 h of NIV (P = 0.024) were independent factors associated with the need for endotracheal intubation. Patients who avoided endotracheal intubation had a significantly lower ICU mortality rate and in-hospital mortality rate than patients who required endotracheal intubation.

CONCLUSION

We determined an APACHE II score of more than 17 and a respiratory rate of more than 25 breaths x min(-1) after 1 h of NIV as factors predicting the need for endotracheal intubation in ALI patients treated with NIV.

Noninvasive mechanical ventilation in patients with chronic obstructive pulmonary disease and severe hypercapnic neurological deterioration in the emergency room

OBJECTIVES

The objective of this study was to assess the effectiveness of noninvasive motion ventilation (NIMV) in patients with chronic obstructive pulmonary disease (COPD), having infectious exacerbation and severe hypercapnic neurological dysfunction in the emergency room.

DESIGN

This is a prospective interventional study.

SETTING

The study setting was the emergency room at the Military Hospital in Guayaquil, Ecuador.

PATIENTS

A total of 24 patients were studied. Twelve patients had acute exacerbation of their chronic obstructive pulmonary disease: they presented at the emergency room with severe neurological dysfunction, with a Glasgow Coma Scale (GCS) score of less than 8 and a pH of less than 7.25. These patients were compared with 12 controls who were being treated with invasive mechanical ventilation (IMV), who were then matched according to their GCS scores, pH status, Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, and age.

INTERVENTIONS

We evaluated the effectiveness and safety of applying a ventilatory strategy based on a biphasic positive airway pressure protocol in the emergency room.

MEASUREMENTS AND RESULTS

The pH, PCO2, and GCS scores, measured during the first 3 h, were predictors of success for the application of NIMV treatment (P<0.05). Mortality was 33.3 and 16.7% for the IMV and the NIMV groups, respectively (P=0.01). Days of IMV were 5.60+/-1.2 versus 3.6+/-1.1 for NIMV (P=0.006). Days of hospitalization were 11.1+/-4.7 for the IMV group and 6.5+/-1.9 for the NIMV group (P=0.001). The cumulative survival rates at 6 months were 71.4 and 80% for the IMV and NIMV groups, respectively (P=0.80).

CONCLUSION

We consider that severe neurological dysfunction and pH of less than 7.25 do not constitute absolute contraindications to the use of NIMV. This kind of management can be implemented in the emergency room with favorable results.

Clinical practice guideline: non-invasive mechanical ventilation as treatment of acute respiratory failure

INTRODUCTION

Non-invasive mechanical ventilation (NIV) has been used to treat acute respiratory failure (ARF) for approximately 20 years. This guideline addresses the indications for, and limitations of, NIV as treatment for ARF according to evidence-based criteria.

METHODS

A panel of experts from 12 scientific medical societies reviewed circa 2900 publications. The panel judged the clinical relevance of these studies and assessed the evidence presented in each, then held two interdisciplinary consensus conferences to formulate guideline recommendations and algorithms.

RESULTS

Whenever possible, NIV should be preferred to invasive mechanical ventilation, in order to avoid the risk of ventilator and tube-associated complications such as nosocomial pneumonia (grade of recommendation A). Particularly in patients with hypercapnic ARF, NIV reduces the rate of hospital-acquired pneumonia, the length of hospital stay and mortality in the intensive care unit and in the hospital (grade of recommendation A). NIV (or continuous positive airway pressure) is also recommended in cardiogenic pulmonary edema (grade of recommendation A), as treatment for ARF in immunocompromised patients (grade of recommendation A), to prevent postextubation failure, to facilitate weaning in patients with hypercapnic ARF (grade of recommendation A), and to improve dyspnea in palliative care (grade of recommendation C). NIV is not generally recommended in patients with hypoxic ARF because of its high failure rate of 30% to over 50% in such patients.

DISCUSSION

Although evidence indicates that NIV can be used as the treatment of first choice for several indications, it is still underutilized in the acute setting. These guidelines provide evidence-based information about the indications for, and limitations of, NIV in the treatment of ARF.

Subject-ventilator synchrony during neural versus pneumatically triggered non-invasive helmet ventilation

Objective

Patient–ventilator synchrony during non-invasive pressure support ventilation with the helmet device is often compromised when conventional pneumatic triggering and cycling-off were used. A possible solution to this shortcoming is to replace the pneumatic triggering with neural triggering and cycling-off—using the diaphragm electrical activity (EA_di). This signal is insensitive to leaks and to the compliance of the ventilator circuit.

Design

Randomized, single-blinded, experimental study.

Setting

University Hospital.

Participants and subjects

Seven healthy human volunteers.

Interventions

Pneumatic triggering and cycling-off were compared to neural triggering and cycling-off during NIV delivered with the helmet.

Measurements and results

Triggering and cycling-off delays, wasted efforts, and breathing comfort were determined during restricted breathing efforts (<20% of voluntary maximum EA_di) with various combinations of pressure support (PSV) (5, 10, 20 cm H₂O) and respiratory rates (10, 20, 30 breath/min). During pneumatic triggering and cycling-off, the subject–ventilator synchrony was progressively more impaired with increasing respiratory rate and levels of PSV (p < 0.001). During neural triggering and cycling-off, effect of increasing respiratory rate and levels of PSV on subject–ventilator synchrony was minimal. Breathing comfort was higher during neural triggering than during pneumatic triggering (p < 0.001).

Conclusions

The present study demonstrates in healthy subjects that subject–ventilator synchrony, trigger effort, and breathing comfort with a helmet interface are considerably less impaired during increasing levels of PSV and respiratory rates with neural triggering and cycling-off, compared to conventional pneumatic triggering and cycling-off.

Electronic supplementary material

The online version of this article (doi:10.1007/s00134-008-1163-z) contains supplementary material, which is available to authorized users.

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.

Mechanical ventilation in patients with hypoxemia due to refractory heart failure

OBJECTIVE

The goal of this study was to evaluate the safety and efficacy of mechanical ventilation (MV), including noninvasive positive pressure ventilation (NPPV) and endotracheal intubation (ETI) in patients with very severe hypoxemia due to refractory heart failure (RHF).

METHODS

In addition to conventional treatment, eighteen patients with hypoxemia due to RHF were assigned to receive NPPV (n=10) or ETI (n=8) based on the severity of their clinical status. Arterial blood gas, PaO(2)/FiO(2), vital signs including respiratory rate (RR), heart rate (HR) and systolic blood pressure (SBP), left ventricular ejection fraction (LVEF) and left ventricular end-diastolic volume (LVEDV) were recorded before and after MV in each group.

RESULTS

The patients in the ETI group showed more severe hypoxemia and respiratory acidosis in comparison with the patients in the NPPV group. Both the NPPV and ETI significantly increased PaO(2), PaO(2)/FiO(2) and arterial oxygen saturation (SaO(2)) (p <0.01) and reduced RR and HR (p <0.01) after MV in comparison to that before MV. Both the NPPV and ETI significantly increased LVEF (p <0.05) and decreased LVEDV (p <0.01) at the time of weaning from MV in comparison to that before MV. Moreover, PaO(2) correlated with LVEF (r=0.882, p=0.01 and r=0.736, p=0.037) while it also inversely correlated with LVEDV (r=-0.645, p=0.044 and r=-0.756, p=0.030) at the time of weaning from MV in the NPPV and ETI groups, respectively. There were two failed cases in the NPPV group. They were transferred immediately to be treated with ETI and were equivalent to the others in the ETI group.

CONCLUSION

Both NPPV and ETI are safe and effective modalities for improving hypoxemia and left heart function in patients with RHF. These results suggest that invasive MV should be applied to very severe patients with RHF as quickly as possible when an expected clinical improvement cannot be obtained by NPPV.

Noninvasive ventilation in acute respiratory failure

BACKGROUND

Noninvasive ventilation has assumed an important role in the management of respiratory failure in critical care units, but it must be used selectively depending on the patient's diagnosis and clinical characteristics.

DATA

We review the strong evidence supporting the use of noninvasive ventilation for acute respiratory failure to prevent intubation in patients with chronic obstructive pulmonary disease exacerbations or acute cardiogenic pulmonary edema, and in immunocompromised patients, as well as to facilitate extubation in patients with chronic obstructive pulmonary disease who require initial intubation. Weaker evidence supports consideration of noninvasive ventilation for chronic obstructive pulmonary disease patients with postoperative or postextubation respiratory failure; patients with acute respiratory failure due to asthma exacerbations, pneumonia, acute lung injury, or acute respiratory distress syndrome; during bronchoscopy; or as a means of preoxygenation before intubation in critically ill patients with severe hypoxemia.

CONCLUSION

Noninvasive ventilation has assumed an important role in managing patients with acute respiratory failure. Patients should be monitored closely for signs of noninvasive ventilation failure and promptly intubated before a crisis develops. The application of noninvasive ventilation by a trained and experienced intensive care unit team, with careful patient selection, should optimize patient outcomes.

Noninvasive positive-pressure ventilation in acute respiratory failure

Noninvasive positive-pressure ventilation is a type of mechanical ventilation that does not require an artificial airway. Studies published in the 1990s that evaluated the efficacy of this technique for the treatment of diseases as chronic obstructive pulmonary disease, congestive heart failure and acute respiratory failure have generalized its use in recent years. Important issues include the selection of the ventilation interface and the type of ventilator. Currently available interfaces include nasal, oronasal and facial masks, mouthpieces and helmets. Comparisons of the available interfaces have not shown one to be clearly superior. Both critical care ventilators and portable ventilators can be used for noninvasive positive-pressure ventilation; however, the choice of ventilator type depends on the patient's condition and therapeutic requirements and on the expertise of the attending staff and the location of care. The best results (decreased need for intubation and decreased mortality) have been reported among patients with exacerbations of chronic obstructive pulmonary disease and cardiogenic pulmonary edema.

Non-invasive ventilation in chronic hypercapnic COPD patients with exacerbation and a pH of 7.35 or higher

BACKGROUND

Current guidelines suggest the use of non-invasive ventilation (NIV) in hypercapnic chronic obstructive pulmonary disease (COPD) exacerbations in patients presenting with a pH of 7.25-7.35. The aim of this study was to investigate the role of NIV in COPD patients with chronic hypercapnic respiratory failure admitted to the hospital with acute exacerbations and an arterial pH of 7.35 or higher.

METHODS

Forty-seven COPD patients with chronic hypercapnic respiratory failure admitted for exacerbations and with a pH of 7.35 or higher were randomized to receive standard medical therapy (control group) or medical therapy plus NIV (NIV group). Arterial blood gases were measured at baseline, after 1 h, 6 h, 12 h, 24 h, 48 h, and at discharge. Need for admission to intensive care unit (ICU), death, and duration of hospitalization were recorded. The final analysis included 42 patients (21 controls and 21 NIV patients).

RESULTS

NIV resulted in a shorter hospital stay (5.5+/-2.6 vs 10.1+/-4.4 days for controls, p=0.0004). Two patients from the control group were admitted to the ICU and one eventually died, whereas all NIV patients were successfully discharged. The NIV group showed a faster improvement in PaCO(2) and pH. At discharge, the NIV group had a lower PaCO(2) (6.5+/-0.6 kPa vs 7.5+/-1.1 kPa, p=0.01) but a comparable pH (7.43+/-0.03 vs 7.43+/-0.04, p=0.93). PaO(2) and PaO(2)/FiO(2) levels showed similar improvement in both groups at discharge.

CONCLUSION

Early administration of NIV in COPD patients with chronic hypercapnic respiratory failure admitted for acute exacerbations with a pH of 7.35 or higher results in a reduced hospital stay and faster improvement of arterial blood gases.

Global strategy for the diagnosis, management, and prevention of chronic obstructive pulmonary disease: GOLD executive summary

Chronic obstructive pulmonary disease (COPD) remains a major public health problem. It is the fourth leading cause of chronic morbidity and mortality in the United States, and is projected to rank fifth in 2020 in burden of disease worldwide, according to a study published by the World Bank/World Health Organization. Yet, COPD remains relatively unknown or ignored by the public as well as public health and government officials. In 1998, in an effort to bring more attention to COPD, its management, and its prevention, a committed group of scientists encouraged the U.S. National Heart, Lung, and Blood Institute and the World Health Organization to form the Global Initiative for Chronic Obstructive Lung Disease (GOLD). Among the important objectives of GOLD are to increase awareness of COPD and to help the millions of people who suffer from this disease and die prematurely of it or its complications. The first step in the GOLD program was to prepare a consensus report, Global Strategy for the Diagnosis, Management, and Prevention of COPD, published in 2001. The present, newly revised document follows the same format as the original consensus report, but has been updated to reflect the many publications on COPD that have appeared. GOLD national leaders, a network of international experts, have initiated investigations of the causes and prevalence of COPD in their countries, and developed innovative approaches for the dissemination and implementation of COPD management guidelines. We appreciate the enormous amount of work the GOLD national leaders have done on behalf of their patients with COPD. Despite the achievements in the 5 years since the GOLD report was originally published, considerable additional work is ahead of us if we are to control this major public health problem. The GOLD initiative will continue to bring COPD to the attention of governments, public health officials, health care workers, and the general public, but a concerted effort by all involved in health care will be necessary.

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.

Noninvasive Ventilation Using a Mouthpiece in Patients with Chronic Obstructive Pulmonary Disease and Acute Respiratory Failure

BACKGROUND

Noninvasive positive pressure ventilation (NPPV) delivered via a mouthpiece (mNPPV) has been successfully used in stable chronic restrictive respiratory insufficiency, but not in patients with chronic obstructive pulmonary disease (COPD) and acute respiratory failure (ARF).

OBJECTIVES

The purpose of this matched case-control study was to compare the usefulness of mNPPV to noninvasive ventilation using a nasal or oronasal mask (nNPPV) or standard medical treatment (SMT) in COPD patients with ARF.

METHODS

Twenty-nine patients receiving mNPPV were matched with 29 patients receiving nNPPV and 29 patients receiving SMT regarding age, SAPSII, admission PaCO(2) and pH.

RESULTS

In the mNPPV group, admission PaCO(2) and pH were 78.6 +/- 12 mm Hg and 7.30 +/- 0.04, respectively. mNPPV and nNPPV avoided the need for endotracheal intubation in 27 and 25 patients, respectively (nonsignificant) whereas SMT resulted in a higher mechanical ventilation rate (13 patients). At the end of the treatment protocol, PaCO(2) was lower in the mNPPV group (62.2 +/- 9.6 mm Hg) than in the SMT group (72.4 +/- 20.4 mm Hg, p < 0.018) leading to a significantly higher pH. No significant differences were observed between the mNPPV and nNPPV groups.

CONCLUSIONS

In case of moderate respiratory acidosis, noninvasive ventilation using a mouthpiece significantly reduces the endotracheal intubation rate in comparison with SMT and therefore appears to be a second-line alternative to noninvasive ventilation delivered via a mask, especially when poorly tolerated.

Outcomes of morbidly obese patients requiring mechanical ventilation for acute respiratory failure*

OBJECTIVE

To examine the outcomes of morbidly obese patients with acute respiratory failure treated with mechanical ventilation.

DESIGN

Retrospective study.

SETTING

A 14-bed medical intensive care unit in an 800-bed university-based hospital.

PATIENTS

A total of 50 morbidly obese subjects with acute respiratory failure requiring ventilatory assistance.

INTERVENTIONS

None.

MEASUREMENTS

Arterial blood gas measurements, intubation rate, days of mechanical ventilation, intensive care unit length of stay, hospital length of stay, and mortality.

RESULTS

From January 1997 to December 2004, 50 morbidly obese patients with acute respiratory failure were treated with mechanical ventilation. Invasive mechanical ventilation was implemented in 17 patients with a mean body mass index of 53.2 +/- 12.2 kg/m2. A total of 33 patients were treated with noninvasive ventilation (NIV), of which 21 avoided intubation (NIV success) and 12 required intubation (NIV failure). Mean body mass index for the NIV success group was significantly less than for the NIV failure group (46.9 +/- 8.9 and 62.5 +/- 16.1 kg/m2, respectively, p = .001). Acute Physiology and Chronic Health Evaluation II scores were similar for patients treated with invasive and noninvasive ventilation. Significant improvements in pH and Paco2 were noted for the invasive mechanical ventilation and NIV success groups. No improvements in gas exchange were noted in the NIV failure group. Of patients treated with NIV, 36% required intubation. Hospital mortality for the invasive ventilation and NIV failure groups was increased.

CONCLUSION

The type of ventilatory assistance may influence clinical outcomes in morbidly obese patients with acute respiratory failure.

Management of Acute Exacerbations of Chronic Obstructive Pulmonary Disease in the Elderly

Chronic obstructive pulmonary disease (COPD) is a debilitating disease with rising worldwide prevalence. Exacerbations of COPD cause significant morbidity and become more common with advancing age. Healthcare providers caring for elderly patients should therefore be familiar with effective treatments for exacerbations of COPD. An extensive body of literature has identified several effective drug therapies for exacerbations. These drugs include inhaled bronchodilators, systemic corticosteroids and antibacterials. The two main classes of inhaled bronchodilators are beta-adrenoceptor agonists and anticholinergics. These drugs optimise lung function during exacerbations, with neither class demonstrating clear superiority over the other. Systemic corticosteroids are effective when used either for inpatient or outpatient treatment of exacerbations. They hasten recovery from exacerbations and reduce relapse rates. Antibacterials decrease morbidity from exacerbations and may decrease mortality in the more severe exacerbations. Other effective therapies for the treatment of acute exacerbations of COPD include oxygen and non-invasive ventilation. Oxygen can be safely administered in acute exacerbations associated with hypoxaemia, with titration of oxygen delivery to a goal oxygen saturation of 90%. Non-invasive ventilation reduces the morbidity and mortality associated with acute exacerbations complicated by hypercapnic respiratory failure. Strategies to prevent COPD exacerbations include smoking cessation, long-acting inhaled beta-adrenoceptor agonists, inhaled long-acting anticholinergics, inhaled corticosteroids and vaccination. Mucolytic agents, pulmonary rehabilitation, and case management programmes may also reduce exacerbation risk, but the current evidence supporting these interventions is weaker.

[Bronchial obstruction in intensive care]

Bronchial obstruction due to one of the major pulmonary diseases asthma, COPD, or emphysema are a common problem in intensive care medicine as the leading cause or as comorbidity. While in pharmacological therapy no major changes have occurred during the last few years, two major advances have been reached in ventilation therapy which are in the focus of this review. First the non invasive ventilation (NIV) has been shown to prove efficient in treating acute on chronic respiratory failure in COPD patients and is capable of shortening the duration of hospital stay. In addition NIV can be used successfully in weaning after long time ventilator therapy and improve prognosis in COPD patients. Secondly the strategy of invasive ventilation therapy has changed significantly. "Permissive hypercapnia" is unequivocally established in severe bronchial obstruction in situations of limited ventilation. When intrinsic PEEP and elevated airway resistance are present PEEP may be useful and the upper limit of airways peak pressure that we are used to in "protective ventilation" of ARDS patients can be necessary and useful to exceed.

Non-invasive ventilation in chronic obstructive pulmonary disease patients: helmet versus facial mask

RATIONALE

The helmet is a new interface with the potential of increasing the success rate of non-invasive ventilation by improving tolerance.

OBJECTIVES

To perform a physiological comparison between the helmet and the conventional facial mask in delivering non-invasive ventilation in hypercapnic patients with chronic obstructive pulmonary disease.

METHODS

Prospective, controlled, randomized study with cross-over design. In 10 patients we evaluated gas exchange, inspiratory effort, patient-ventilator synchrony and patient tolerance after 30 min of non-invasive ventilation delivered either by helmet or facial mask; both trials were preceded by periods of spontaneous unassisted breathing.

MEASUREMENTS

Arterial blood gases, inspiratory effort, duration of diaphragm contraction and ventilator assistance, effort-to-support delays (at the beginning and at the end of inspiration), number of ineffective efforts, and patient comfort.

MAIN RESULTS

Non-invasive ventilation improved gas exchange (p<0.05) and inspiratory effort (p<0.01) with both interfaces. The helmet, however, was less efficient than the mask in reducing inspiratory effort (p<0.05) and worsened the patient-ventilator synchrony, as indicated by the longer delays to trigger on (p<0.05) and cycle off (p<0.05) the mechanical assistance and by the number of ineffective efforts (p<0.005). Patient comfort was no different with the two interfaces.

CONCLUSIONS

Helmet and facial mask were equally tolerated and both were effective in ameliorating gas exchange and decreasing inspiratory effort. The helmet, however, was less efficient in decreasing inspiratory effort and worsened the patient-ventilator interaction.

Benefits and risks of success or failure of noninvasive ventilation

OBJECTIVE

Noninvasive ventilation (NIV) fails more frequently for de novo acute respiratory failure (de novo) than for cardiogenic pulmonary edema (CPE) or acute-on-chronic respiratory failure (AOC). The impact of NIV failure and success was compared between de novo and CPE or AOC after adjustment for disease severity.

SETTINGS

Patients requiring ventilatory support were enrolled in a prospective survey in 70 French ICUs. Of 1076 patients requiring ventilatory support, 524 were eligible, including 299 de novo (NIV use, 30%) and 225 CPE-AOC (NIV use, 55%).

DESIGN AND ANALYSIS

Independent risk factors associated with mortality and length of stay were identified by logistic regression analysis. The adjusted outcome of NIV success or failure was compared to that with endotracheal intubation without NIV.

RESULTS

NIV success was independently associated with survival in both de novo, adjusted OR 0.05 (95% CI 0.01-0.42), and CPE-AOC OR 0.03 (CI 0.01-0.24). NIV failure was associated with ICU mortality in the de novo group (OR 3.24, CI 1.61-6.53) but not in the CPE-AOC group. Nosocomial pneumonia was less common in patients successful with NIV. NIV failure was associated with a longer ICU stay in CPE-AOC only. The overall use of NIV was independently associated with a better outcome only in CPE-AOC patients (OR 0.33, CI 0.15-0.73).

CONCLUSION

The effect of NIV differs between de novo and CPE-AOC patients because NIV failure is associated with increased mortality for de novo patients. This finding should raise a note of caution when applying NIV in this indication.

The pathophysiology of emphysema: considerations for critical care nursing practice

Emphysema is caused by exposure to cigarette smoking as well as alpha(1)-antitrypsin deficiency. It has been estimated to cost the National Health Service (NHS) in excess of 800 million pounds per year in related health care costs. The challenges for Critical Care nurses are those associated with dynamic hyperinflation, Auto-PEEP, malnutrition and the weaning from invasive and non-invasive mechanical ventilation. In this paper we consider the impact of the pathophysiology of emphysema, its effects on other body systems as well as the impact acute exacerbations have when patients are admitted to the Intensive Care Unit.

Management of acute ventilatory failure

Acute ventilatory failure is a challenging yet increasingly common medical emergency reflecting the growing burden of respiratory disease. It is not a diagnosis in itself but the end result of a diversity of disease processes culminating in arterial hypoxaemia and hypercapnia. This review focuses on key management issues including giving appropriate oxygen therapy, treatment of the underlying aetiology as well as any precipitant factors and provision of assisted ventilation if required. Ventilatory assistance can be provided both invasively and non-invasively and the indications for either or both forms of assisted ventilation are discussed. Further emphasis is needed regarding advanced directives of care and clinicians should be aware of ethical issues regarding assisted ventilation.

The use of noninvasive mechanical ventilation in COPD with severe hypercapnic acidosis

STUDY OBJECTIVES

To compare the effect of noninvasive mechanical ventilation (NIV) in severely acidotic with mildly acidotic patients with acute hypercapnic chronic obstructive lung disease (COPD).

DESIGN

Comparison of NIV in consecutively enrolled patients with acute hypercapnic COPD with mild (pH 7.25-7.35) or severe (pH<7.25) acidosis on time to normalise pH and improve PaCO(2), duration of NIV treatment, length of stay in hospital and survival. Results (meadian (IQR)): Twenty-nine patients had 36 episodes of acute hypercapnic respiratory failure: Seventeen with pH<7.25 and 19 with pH 7.25-7.34. Compared with the mildly acidotic group, the severely acidotic group took a similar length of time for pH to normalise and PaCO(2) improve (12 (6-34) vs 12 (4-28)h, respectively, P=0.42), with similar duration of NIV treatment (60 (35-96) vs 68 (36-48)h, respectively, P=0.25) and hospital length of stay (8 (7-18) vs 9 (5-17) days, respectively, P=0.61). Overall survival was 89%, with 95% in the mild and 82% in the severely acidotic groups.

CONCLUSIONS

Noninvasive ventilation is effective in the treatment of patients with severe acidosis due to acute hypercapnic COPD.

Influence of Two Different Interfaces for Noninvasive Ventilation Compared to Invasive Ventilation on the Mechanical Properties and Performance of a Respiratory System

BACKGROUND

Noninvasive ventilation (NIV) is increasingly used in intensive care medicine, but only little information is available how different NIV interfaces affect the performance of a ventilatory system. Therefore, we compared delay times, pressure time products (PTPs), and wasted efforts during inspiration among patients receiving invasive ventilation and NIV with a helmet (NIV-h) or a face mask (NIV-fm).

METHODS

Using an in vitro lung model capable of simulating spontaneous breathing, gas flow and airway pressure were measured with varying positive end-expiratory pressure and pressure support (PS) levels. Wasted efforts were determined while lung compliance, respiratory rate (RR), continuous positive airway pressure (CPAP), and PS levels were changed.

RESULTS

Delay times were more than twice as long with a helmet compared to NIV-fm or invasive ventilation (p < 0.001), but decreased during NIV-h with increasing CPAP (p < 0.001) and PS levels (p < 0.001). During the initial inspiratory phase, PTP was smaller with NIV-h compared to NIV-fm or invasive ventilation, but not so when a complete inspiration with PS was evaluated. Wasted efforts occurred earlier during NIV-h and were aggravated with rising PS, RR, and compliance.

CONCLUSIONS

Although delay times are prolonged during NIV-h, PTP is initially smaller compared to NIV-fm and invasive ventilation, indicating less work of breathing due to the high volume the patient can access. Increasing the CPAP or PS level decreases delay times in NIV-h and should therefore be considered whenever possible. Wasted inspiratory efforts occurred at higher RRs and should carefully be monitored during NIV.

Transtracheal Open Ventilation in Acute Respiratory Failure Secondary to Severe Chronic Obstructive Pulmonary Disease Exacerbation

RATIONALE

Patients who fail noninvasive ventilation are generally intubated and are then subjected to complications of invasive mechanical ventilation. With transtracheal open ventilation, ventilator support is delivered through an uncuffed small bore minitracheostomy tube, which eliminates pooling of secretions above the cuff and thus reduces the risk of tracheobronchial microbial colonization.

OBJECTIVE

To compare transtracheal open ventilation (treatment group) with conventional invasive ventilation (control group) in patients with exacerbation of chronic obstructive pulmonary disease who initially failed noninvasive ventilation.

METHODS

Patients were randomized to receive trans-tracheal open ventilation (n=19) or conventional invasive ventilation (n=20).

MEASUREMENTS AND MAIN RESULTS

There was no difference in arterial blood gases after 1 and 30 h between the two groups. Two patients receiving transtracheal open ventilation and 13 undergoing conventional ventilation had complications (p<0.0001). Compared with conventional ventilation, transtracheal open ventilation significantly decreased both the duration of mechanical ventilation (7.6+/-4.7 vs. 18.6+/-10.6 d, p<0.0001) and length of stay in the intensive care unit (10.2+/-4.5 vs. 21.3+/-9.7 d, p<0.0001).

CONCLUSIONS

Transtracheal open ventilation was as effective as conventional ventilation in maintaining adequate gas exchange and reducing complications, duration of mechanical ventilation, and intensive care unit length of stay.

Pronóstico de los enfermos con enfermedad pulmonar obstructiva crónica reagudizada que precisan ventilación mecánica

OBJECTIVE

To determine the variables associated with prognosis for acute exacerbation of chronic obstructive pulmonary disease (AECOPD) in mechanically ventilated patients.

DESIGN

Prospective cohort study with retrospective analysis.

LOCATION

361 Intensive Care Units (ICU) in 20 countries.

PATIENTS AND METHODS

There were included in the study 522 patients who required mechanical ventilation for more than 12 hours due to an acute exacerbation of chronic obstructive pulmonary disease (AECOPD). In order to determine those variables associated with mortality, there was performed a recursive partition analysis in which the following variables were included: demographics, arterial blood gas prior to intubation, complications arising during mechanical ventilation (barotrauma, acute respiratory distress syndrome, ventilator-associated pneumonia, sepsis), organ dysfunction (cardiovascular, renal, liver, coagulation) and duration of ventilatory support.

INTERVENTIONS

None. VARIABLES OF PRIME IMPORTANCE: ICU mortality.

RESULTS

ICU and hospital mortality rates were 22% and 30%, respectively. Variables associated with mortality were cardiovascular dysfunction, renal dysfunction and duration of ventilatory support > 18 days. Median durations were as follows: mechanical ventilatory support, 4 days (P25: 2, P75: 6); weaning from ventilatory support, 2 days (P25: 1, P75: 5); stay in intensive care unit, 8 days (P25: 5, P75: 13); stay in hospital, 17 days (P25: 10, P75: 27).

CONCLUSIONS

Mortality in the studied cohort of patients with AECOPD was associated with cardiovascular dysfunction, renal dysfunction and prolonged mechanical support.

Time of non-invasive ventilation

Non-invasive ventilation (NIV) is a safe, versatile and effective technique that can avert side effects and complications associated with endotracheal intubation. The success of NIV relies on several factors, including the type and severity of acute respiratory failure, the underlying disease, the location of treatment, and the experience of the team. The time factor is also important. NIV is primarily used to avert the need for endotracheal intubation in patients with early-stage acute respiratory failure and post-extubation respiratory failure. It can also be used as an alternative to invasive ventilation at a more advanced stage of acute respiratory failure or to facilitate the process of weaning from mechanical ventilation. NIV has been used to prevent development of acute respiratory failure or post-extubation respiratory failure. The number of days of NIV and hours of daily use differ, depending on the severity and course of the acute respiratory failure and the timing of application. In this review article, we analyse, compare and discuss the results of studies in which NIV was applied at various times during the evolution of acute respiratory failure.

Noninvasive vs conventional mechanical ventilation in acute respiratory failure: a multicenter, randomized controlled trial

STUDY OBJECTIVE

Noninvasive mechanical ventilation (NIMV) is beneficial for patients with acute respiratory failure (ARF) when added to medical treatment. However, its role as an alternative to conventional mechanical ventilation (CMV) remains controversial. Our aim was to compare the efficacy and resource consumption of NIMV against CMV in patients with ARF.

DESIGN

A randomized, multicenter, controlled trial.

SETTING

Seven multipurpose ICUs.

PATIENTS

Sixty-four patients with ARF from various causes who fulfilled criteria for mechanical ventilation.

INTERVENTION

The noninvasive group received ventilation through a face mask in pressure-support mode plus positive end-expiratory pressure; the conventional group received ventilation through a tracheal tube.

MEASUREMENTS AND RESULTS

Avoidance of intubation, mortality, and consumption of resources were the outcome variables. Thirty-one patients were assigned to the noninvasive group, and 33 were assigned to the conventional group. In the noninvasive group, 58% patients were intubated, vs 100% in the conventional group (relative risk reduction, 43%; p < 0.001). Stratification by type of ARF gave similar results. In the ICU, death occurred in 23% and 39% (p = 0.09) and complications occurred in 52% and 70% (p = 0.07) in the noninvasive and conventional groups, respectively. There were no differences in length of stay. The Therapeutic Intervention Score System-28, but not the direct nursing activity time, was lower in the noninvasive group during the first 3 days.

CONCLUSIONS

NIMV reduces the need for intubation and therapeutic intervention in patients with ARF from different causes. There is a nonsignificant trend of reduction in ICUs and hospital mortality together with fewer complications during ICU stay.

Noninvasive positive pressure ventilation in patients with acute exacerbations of COPD and varying levels of consciousness

STUDY OBJECTIVES

A severely altered level of consciousness (ALC) has been considered a contraindication to noninvasive positive pressure ventilation (NPPV). We compared the clinical outcome of patients with acute respiratory failure (ARF) due to COPD exacerbations and different degrees of ALC.

DESIGN

A 5-year case-control study with a prospective data collection.

SETTING

Respiratory Monitoring Unit.

PATIENTS

Eighty of 153 consecutive COPD patients requiring NPPV for ARF were divided into four groups, which were carefully matched for the main physiologic variables, according to the level of consciousness assessed with the Kelly-Matthay Score, in which 1 is normal (control subjects) and 6 is severely impaired.

MEASUREMENT AND RESULTS

Changes from baseline in arterial blood gas (ABG) levels and Kelly score, the rate and causes of NPPV failure, the rate of nosocomial pneumonia, and the 90-day mortality rate were compared. NPPV significantly improved ABG levels and Kelly score in all groups after 1 to 2 h. NPPV failure (Kelly score 1 = 15%; Kelly score 2 = 25%; Kelly score 3 = 30%; Kelly score > 3 = 45%) and 90-day mortality rate (Kelly score 1 = 20%; Kelly score 2 = 35%; Kelly score 3 = 35%; Kelly score > 3 = 50%) significantly increased with the worsening of the level of consciousness. Using a multivariate analysis, the acute nonrespiratory component of the acute physiology and chronic health evaluation (APACHE) III score, and baseline pH independently predicted baseline Kelly score. After 1 to 2 h of NPPV, changes in the Kelly score were associated with those in pH. No correlation was found with Pa(CO2).

CONCLUSIONS

This study confirms that NPPV may be successfully applied to patients experiencing COPD exacerbations with milder ALCs, whereas the rate of failure in patients with severely ALCs (ie, Kelly score > 3) is higher, even though better than expected, so that an initial and cautious attempt with NPPV may be performed even in this latter group. Changes in the level of consciousness induced by NPPV are not correlated with those in Pa(CO2).

Noninvasive positive pressure ventilation in the intensive care unit: A concise review

OBJECTIVE

To critically assess available high-level clinical studies regarding use of noninvasive positive pressure ventilation in varied intensive care unit settings.

DATA SOURCE

Search of pertinent articles within Ovid MEDLINE from 1975 to 2005, CINAHL from 1982 to 2005, EMBASE from 1988 to 2005, and Web of Science from 1993 to 2005.

STUDY SELECTION

Randomized, controlled clinical trials and cohort studies and observational studies the authors consider important or novel.

DATA EXTRACTION/SYNTHESIS

Performed equally by both authors with the use of an Excel data spreadsheet.

CONCLUSION

There is abundant level I evidence supporting the use of noninvasive positive pressure ventilation in such critical care settings as acute hypercapnic respiratory failure, particularly related to chronic obstructive pulmonary disease, and acute cardiogenic pulmonary edema. We also report on other clinical scenarios in which the data may be somewhat less compelling, but evidence favors a noninvasive positive pressure ventilation trial. Some well designed studies suggest that noninvasive positive pressure ventilation is not an appropriate intervention for patients who have failed endotracheal extubation.

Effects of alveolar dead-space, shunt andV˙/Q˙distribution on respiratory dead-space measurements

BACKGROUND

Respiratory dead-space is often increased in lung disease. This study evaluates the effects of increased alveolar dead-space (Vd(alv)), pulmonary shunt, and abnormal ventilation perfusion ratio (/) distributions on dead-space and alveolar partial pressure of carbon dioxide (Pa(co(2))) calculated by various methods, assesses a recently published non-invasive method (Koulouris method) for the measurement of Bohr dead-space, and evaluates an equation for calculating physiological dead-space (Vd(phys)) in the presence of pulmonary shunt.

METHODS

Pulmonary shunt, / distribution and Vd(alv) were varied in a tidally breathing cardiorespiratory model. Respiratory data generated by the model were analysed to calculate dead-spaces by the Fowler, Bohr, Bohr-Enghoff and Koulouris methods. Pa(co(2)) was calculated by the method of Koulouris.

RESULTS

When Vd(alv) is increased, Vd(phys) can be recovered by the Bohr and Bohr-Enghoff equations, but not by the Koulouris method. Shunt increases the calculated Bohr-Enghoff dead-space, but does not affect Fowler, Bohr or Koulouris dead-spaces, or Vd(phys) estimated by the shunt-corrected equation if pulmonary artery catheterization is available. Bohr-Enghoff but not Koulouris or Fowler dead-space increases with increasing severity of / maldistribution. When alveolar Pco(2) is increased by any mechanism, Pa(co(2)) calculated by Koulouris' method does not agree well with average alveolar Pco(2).

CONCLUSIONS

Our studies show that increased pulmonary shunt causes an apparent increase in Vd(phys), and that abnormal / distributions affect the calculated Vd(phys) and Vd(alv), but not Fowler dead-space. Dead-space and Pa(co(2)) calculated by the Koulouris method do not represent true Bohr dead-space and Pa(co(2)) respectively, but the shunt-corrected equation performs well.

Noninvasive ventilation in hypercapnic acute respiratory failure due to chronic obstructive pulmonary disease vs. other conditions: effectiveness and predictors of failure

OBJECTIVE

This study compared the effectiveness of noninvasive ventilation (NIV) and the risk factors for NIV failure in hypercapnic acute respiratory failure (ARF) due to chronic obstructive pulmonary disease (COPD) vs. non-COPD conditions.

DESIGN AND SETTING

Prospective cohort study in the medical intensive care unit of a university hospital.

PATIENTS AND PARTICIPANTS

111 patients with hypercapnic ARF, 43 of whom had COPD exacerbations and 68 other conditions. Baseline characteristics of the two groups were similar.

MEASUREMENTS AND RESULTS

The risk of NIV failure, defined as the need for endotracheal intubation, was significantly lower in COPD than in other conditions (19% vs. 47%). High APACHE II score was an independent predictor of NIV failure in COPD (OR 5.38 per 5 points). The presence of pneumonia (OR 5.63), high APACHE II score (OR 2.59 per 5 points), rapid heart rate (OR 1.22 per 5 beats/min), and high PaCO(2) 1 h after NIV (OR 1.22 per 5 mmHg) were independent predictors of NIV failure in the non-COPD group. Failure of NIV independently predicted mortality (OR 10.53).

CONCLUSIONS

Noninvasive ventilation was more effective in preventing endotracheal intubation in hypercapnic ARF due to COPD than non-COPD conditions. High APACHE II score predicted NIV failure in both groups. Noninvasive ventilation was least effective in patients with hypercapnic ARF due to pneumonia.

How to choose a mechanical ventilator

PURPOSE OF REVIEW

To provide some practical and clinical considerations that may guide users through the decision process when choosing mechanical ventilators

RECENT FINDINGS

Although the complexity of mechanical ventilators is steadily increasing, the importance of many devices developed over the course of the technical evolution is still a matter of discussion. Recent data demonstrate that the technical performance of equivalent ventilators (ie, machines of the same generation and category) is pretty similar, suggesting that the different manufacturers keep in step with new developments. Thus, other factors than technical limitations will probably influence the choice of ventilators. Among them the ability of the staff to understand the rationale of the different devices and controls as well as deal with the complexity of the ventilator may be particularly important.

SUMMARY

Choosing mechanical ventilators should begin by defining the algorithms of how to ventilate a patient. Once this is done, a ventilator should allow the transformation of specific strategies into practice and the adaptation of the mechanical support to the needs of the individual patient. This procedure is crucially important, because ventilator therapy should always be determined by the physician and based on solid physiologic rationales rather than by the technical features of the machine.

Noninvasive vs invasive ventilation in COPD patients with severe acute respiratory failure deemed to require ventilatory assistance

OBJECTIVE

To determine whether non-invasive ventilation (NIV) may be an effective and safe alternative to invasive mechanical ventilation in chronic obstructive pulmonary disease (COPD) patients with acute respiratory failure (ARF) meeting criteria for mechanical ventilation.

DESIGN AND SETTING

Matched case-control study conducted in ICU.

PATIENTS AND INTERVENTION

NIV was prospectively applied to 64 COPD patients with advanced ARF. Their outcomes were compared with those of a control group of 64 COPD patients matched on age, FEV(1), Simplified Acute Physiology Score II, and pH at ICU admission, previously treated in the same ICU with conventional invasive mechanical ventilation.

METHODS AND RESULTS

NIV failed in 40 patients who required intubation. Mortality rate, duration of mechanical ventilation, and lengths of ICU and post-ICU stay were not different between the two groups. The NIV group had fewer complications ( P = 0.01) and showed a trend toward a lower proportion of patients remaining on mechanical ventilation after 30 days ( P = 0.056). Compared to the control group, the outcomes of the patients who failed NIV were no different. Compared to the patients who received intubation, those who succeeded NIV had reduced mortality rate and lengths of ICU and post-ICU stay.

CONCLUSIONS

In COPD patients with advanced hypercapnic acute respiratory failure, NIV had a high rate of failure, but, nevertheless, provided some advantages, compared to conventional invasive ventilation. Subgroup analysis suggested that the delay in intubation was not deleterious in the patients who failed NIV, whereas a better outcome was confirmed for the patients who avoided intubation.

Non-invasive negative and positive pressure ventilation in the treatment of acute on chronic respiratory failure

OBJECTIVE

To investigate in clinical practice the role of non-invasive mechanical ventilation in the treatment of acute respiratory failure on chronic respiratory disorders.

DESIGN

An 18 months prospective cohort study.

SETTING

A specialised respiratory intensive care unit in a university-affiliated hospital.

PATIENTS

A total of 258 consecutive patients with acute respiratory failure on chronic respiratory disorders.

INTERVENTIONS

Criteria for starting non-invasive mechanical ventilation and for endotracheal intubation were predefined. Non-invasive mechanical ventilation was provided by positive pressure (NPPV) ventilators or iron lung (NPV).

RESULTS

The main characteristics of patients (70% with chronic obstructive pulmonary disease) on admission were (mean, SD or median, 25th-75th centiles): pH 7.29 (0.07), PaCO(2) 83 mm Hg (19), PaO(2)/FiO(2) 198 (77), APACHE II score 19 (15-24). Among the 258 patients, 200 (77%) were treated exclusively with non-invasive mechanical ventilation (40% with NPV, 23% with NPPV, and 14% with the sequential use of both), and 35 (14%) with invasive mechanical ventilation. In patients in whom NPV or NPPV failed, the sequential use of the alternative non-invasive ventilatory technique allowed a significant reduction in the failure of non-invasive mechanical ventilation (from 23.4 to 8.8%, p=0.002, and from 25.3 to 5%, p=0.0001, respectively). In patients as a whole, the hospital mortality (21%) was lower than that estimated by APACHE II score (28%).

CONCLUSIONS

Using NPV and NPPV it was possible in clinical practice to avoid endotracheal intubation in the large majority of unselected patients with acute respiratory failure on chronic respiratory disorders needing ventilatory support. The sequential use of both modalities may increase further the effectiveness of non-invasive mechanical ventilation.

Non-invasive ventilation for acute respiratory disease

Non-invasive ventilation (NIV) has been shown to be effective in acute respiratory failure of various aetiologies in different health care systems and ward settings. It should be seen as complementary to invasive ventilation and primarily a means of preventing some patients from deteriorating to the point at which intubation is needed. Generally it is best initiated early before assisted ventilation is mandatory, although it has been shown to be effective even in very sick patients. Important benefits include the avoidance of endotracheal-tube-associated infections, which carry an important morbidity and mortality, and a reduction in health care costs. The most important ingredient for an acute NIV service is a well-trained enthusiastic ward team.

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.

Anaesthetic considerations in patients with chronic pulmonary disease

PURPOSE OF REVIEW

Chronic pulmonary diseases are getting more important in daily anaesthetic practice, because prevalence is increasing and improved anaesthetic techniques have led to the abandonment of previous contraindications to anaesthesia. It is therefore essential for the anaesthetist to be up to date with current clinical concepts and their impact on the conduction of anaesthesia as well as new insights into how to anaesthetise these patients safely.

RECENT FINDINGS

If patients are treated adequately, open and minimally invasive operations can be safely performed under regional and general anaesthesia. The management of acute exacerbations remains challenging, and first-line medical treatment should be supported by non-invasive ventilation. In controlled mechanical ventilation, parameters should be set to avoid dynamic hyperinflation.

SUMMARY

Assessing the functional status of patients admitted for surgery remains a difficult task, and in patients identified as being at risk by clinical examination additional spirometry and blood gas measurements may be helpful. If there are flow limitations and signs of respiratory failure, the anaesthetist should be highly alarmed and monitor the patient closely and invasively, yet there is no reason to deny any patient a substantially beneficial operation.

Recently published papers: a number of treatment controversies

In the present commentary I review some current therapeutic debates. Is noninvasive ventilation going to become the gold standard for acute hypercapnic respiratory failure, and if we have to intubate and ventilate then what is the gold standard for sedation? Old therapies are challenged (e.g. diuretics may worsen outcome) and new ones suggested (e.g. some critically ill patients may benefit from regular erythropoietin). In addition, we must of course mention steroids and sepsis.