Intermittent positive pressure ventilation via nasal access in the management of respiratory insufficiency

Ventilators, Settings, Autotitration Algorithms

The choice of a ventilator model for a single patient is usually based on parameters such as size (portability), presence or absence of battery and ventilatory modes. However, there are many details within each ventilator model about triggering, pressurisation or autotitration algorithms that may go unnoticed, but may be important or may justify some drawbacks that may occur during their use in individual patients. This review is intended to emphasize these differences. Guidance is also provided on the operation of autotitration algorithms, in which the ventilator is able to take decisions based on a measured or estimated parameter. It is important to know how they work and their potential sources of error. Current evidence on their use is also provided.

Proposals from a French expert panel for respiratory care in ALS patients

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive diaphragm weakness and deteriorating lung function. Bulbar involvement and cough weakness contribute to respiratory morbidity and mortality. ALS-related respiratory failure significantly affects quality of life and is the leading cause of death. Non-invasive ventilation (NIV), which is the main recognized treatment for alleviating the symptoms of respiratory failure, prolongs survival and improves quality of life. However, the optimal timing for the initiation of NIV is still a matter of debate. NIV is a complex intervention. Multiple factors influence the efficacy of NIV and patient adherence. The aim of this work was to develop practical evidence-based advices to standardize the respiratory care of ALS patients in French tertiary care centres.

METHODS

For each proposal, a French expert panel systematically searched an indexed bibliography and prepared a written literature review that was then shared and discussed. A combined draft was prepared by the chairman for further discussion. All of the proposals were unanimously approved by the expert panel.

RESULTS

The French expert panel updated the criteria for initiating NIV in ALS patients. The most recent criteria were established in 2005. Practical advice for NIV initiation were included and the value of each tool available for NIV monitoring was reviewed. A strategy to optimize NIV parameters was suggested. Revisions were also suggested for the use of mechanically assisted cough devices in ALS patients.

CONCLUSION

Our French expert panel proposes an evidence-based review to update the respiratory care recommendations for ALS patients in daily practice.

Continuous noninvasive ventilatory support outcomes for patients with neuromuscular disease: a multicenter data collaboration

BACKGROUND

Typically, patients with progressive neuromuscular disorders (NMDs) develop acute respiratory failure (ARF), are intubated, and when failing spontaneous breathing trials (SBTs) undergo a tracheotomy and receive tracheostomy mechanical ventilation (TMV). However, increasing numbers of patients use nasal noninvasive ventilation (NIV), initially for sleep and this is extended to continuous dependence (CNVS). This can be used as a strategy to assist in successful extubation . We retrospectively reviewed 19 centers offering CNVS and mechanical insufflation-exsufflation (MI-E) as an alternative to TMV.

METHODS

Centers with publications or presentations concerning CNVS outcomes data were pooled for amyotrophic lateral sclerosis (ALS), Duchenne muscular dystrophy (DMD), and spinal muscular atrophy type 1 (SMA1). Progression to CNVS dependence without hospitalization, duration of dependence, and extubations and decannulations to CNVS were recorded. Prolongation of life was defined by duration of CNVS dependence without ventilator free breathing ability (VFBA).

RESULTS

There were 1623 part time (<23 h/day) NVS users with ALS, DMD, and SMA1 from 19 centers in 16 countries of whom 761 (47%) were CNVS dependent for 2218 patient-years. This included: 335 ALS patients for a mean 1.2 ± 1.0 (range to 8) years each; 385 DMD patients for 5.4 ± 1.6 (range to 29) years; and 41 SMA1 patients for 5.9 ± 1.8 (range to 20) years. Thirty-five DMD and ALS TMV users were decannulated to CNVS and MI-E. At data collection 494 (65%) patients were CNVS dependent but 110 (74 of whom with bulbar ALS), had undergone tracheotomies.

CONCLUSIONS

ALS, DMD, and SMA1 patients can become CNVS dependent without requiring hospitalization but CNVS cannot be used indefinitely for many patients with advanced upper motor neuron diseases.

Transcutaneous Carbon Dioxide Measurement in Adult Patients with Neuromuscular Disorders: A quality Level Assessment

Background: Carbon dioxide tension (PCO2) monitoring during sleep, is crucial to identify respiratory failure in patients with neuromuscular disorders (NMD). Transcutaneous PCO2 monitoring is an available technique to measure PCO2. Objectives: To assess the quality level of transcutaneous blood gas measurements via SenTec monitor. Methods: A 12-month analysis of SenTec measurements was conducted in a Belgian Centre for Home Mechanical Ventilation (HMV). Over two consecutive nights; SpO2 and PCO2 measurements, the presence of PCO2 drift and drift correction with SenTec, were reviewed and scores (0, 1, 2 for poor, medium and high level) were assigned to estimate the quality of measurements. Results: Sixty-nine NMD patients met the inclusion criteria, of which 48/69 used HMV. PCO2 drift and drift correction were present in 15% and 68% of the 138 recordings, respectively. The quality level of measurements throughout night 1, scored 1.55 (0–2). The relevance of our clinical findings from SenTec scoring 1.94 (1–2); was considered highly satisfactory. HMV was ineffective in 24/48 patients. Among 12 patients with hypercapnia, 8 patients improved PCO2 between night 1 and 2. Among 12 patients with hypocapnia, PCO2 improved in 4/12 patients, who reached the range of normal PCO2 (35–47 mmHg). Conclusions: The quality of SenTec measurements was acceptable in the majority of recordings and clinical findings were deemed satisfactory in all cases. A single SenTec measurement was sufficient to determine the need for NIV. However, two SenTec registrations were insufficient to both improve NIV effectiveness in 50% of cases, and, to ensure follow-up of our interventions.

Noninvasive Ventilator Devices and Modes

Noninvasive ventilation has become an increasingly common treatment strategy for patients with diverse conditions involving chronic respiratory failure. An intimate understanding of various advanced respiratory devices and modes is essential in the management of these patients. Pressure-limited modes of ventilation are more commonly used than volume modes for noninvasive ventilation owing to enhanced patient comfort and synchrony with the ventilator, as well as improved leak compensation. Common pressure modes include spontaneous/timed and pressure control, with volume-assured pressure support being an additive feature available on certain devices. Evidence guiding the optimal mode of ventilation for specific diseases is limited.

Daytime noninvasive ventilatory support for patients with ventilatory pump failure: a narrative review

Over the past three decades, the use of noninvasive ventilation or "NIV" to assuage symptoms of hypoventilation for patients with early onset or mild ventilatory pump failure has been extended to up to the use of continuous noninvasive ventilatory support (CNVS) at full ventilatory support settings as a definitive alternative to tracheostomy mechanical ventilation. NVS, along with mechanical insufflation-exsufflation, now provides a noninvasive option for the management of both chronic and acute respiratory failure for these patients. The most common diagnoses for which these methods are useful include chest wall deformities, neuromuscular diseases, morbid obesity, high level spinal cord injury and idiopathic, primary or secondary disorders of the ventilatory control. Thus, NVS is being used in diverse settings: critical care units, medical wards, at home, and in extended care. The aim of this review is to examine the techniques used for daytime support.

NIV in amyotrophic lateral sclerosis: The 'when' and 'how' of the matter

Non-invasive ventilation (NIV) has become an essential part of the treatment of amyotrophic lateral sclerosis (ALS) since 2006. NIV very significantly improves survival, quality of life and cognitive performances. The initial NIV settings are simple, but progression of the disease, ventilator dependence and upper airway involvement sometimes make long-term adjustment of NIV more difficult, with a major impact on survival. Unique data concerning the long-term adjustment of NIV in ALS show that correction of leaks, management of obstructive apnoea and adaptation to the patient's degree of ventilator dependence improve the prognosis. Non-ventilatory factors also impact the efficacy of NIV and various solutions have been described and must be applied, including cough assist techniques, control of excess salivation and renutrition. NIV in ALS has been considerably improved as a result of application of all of these measures, avoiding the need for tracheostomy in the very great majority of cases. More advanced use of NIV also requires pulmonologists to master the associated end-of-life palliative care, as well as the modalities of discontinuing ventilation when it becomes unreasonable.

Noninvasive Positive Pressure Ventilation for Acute Respiratory Failure in Emergency Department: a Qualitative Review

The roles of noninvasive positive pressure ventilation (NIPPV) as a treatment modality for patients presenting with acute respiratory failure (ARF) to the emergency department (ED) have not been clearly identified. The major advantages of NIPPV are avoiding patient's discomforts and complications relating to endotracheal intubation and mechanical ventilation. This review is to explore the current evidence on the effectiveness of NIPPV in various subgroups of patients with ARF. The rationales, advantages, complications and contraindications in the usage of NIPPV will also be discussed. There is robust evidence to support the use of NIPPV in severe acute exacerbation of chronic obstructive airway disease (COAD). A modest amount of favourable evidence supports the use of Continuous Positive Airway Pressure (CPAP) in cardiogenic pulmonary oedema, although the potential for harm has not been excluded. There exists no solid evidence supporting the use of NIPPV in asthma and pneumonia. Early institution of NIPPV in the ED is appropriate, feasible, likely to be beneficial and without major complications. Further good quality studies to evaluate the roles of NIPPV for ARF in the ED setting are needed to define which groups of patients can gain most benefit from this type of treatment.

Noninvasive Positive Pressure Ventilatory Support Begins During Sleep

The goal of sleep doctors has been to titrate away apneas and hypopneas using noninvasive ventilation, a term that has become synonymous with continuous positive airway pressure and bilevel positive airway pressure at the lowest effective bilevel settings. It is now time to appreciate noninvasive ventilatory support as an alternative to invasive mechanical ventilation. This article discusses mechanisms of action, two paradigms, and ancillary techniques for noninvasive ventilatory support.

Noninvasive Respiratory Management of Patients With Neuromuscular Disease

This review article describes definitive noninvasive respiratory management of respiratory muscle dysfunction to eliminate need to resort to tracheotomy. In 2010 clinicians from 22 centers in 18 countries reported 1,623 spinal muscular atrophy type 1 (SMA1), Duchenne muscular dystrophy (DMD), and amyotrophic lateral sclerosis users of noninvasive ventilatory support (NVS) of whom 760 required it continuously (CNVS). The CNVS sustained their lives by over 3,000 patient-years without resort to indwelling tracheostomy tubes. These centers have now extubated at least 74 consecutive ventilator unweanable patients with DMD, over 95% of CNVS-dependent patients with SMA1, and hundreds of others with advanced neuromuscular disorders (NMDs) without resort to tracheotomy. Two centers reported a 99% success rate at extubating 258 ventilator unweanable patients without resort to tracheotomy. Patients with myopathic or lower motor neuron disorders can be managed noninvasively by up to CNVS, indefinitely, despite having little or no measurable vital capacity, with the use of physical medicine respiratory muscle aids. Ventilator-dependent patients can be decannulated of their tracheostomy tubes.

AJRCCM: 100-Year Anniversary. Homeward Bound: A Centenary of Home Mechanical Ventilation

The evolution of home mechanical ventilation is an intertwined chronicle of negative and positive pressure modes and their role in managing ventilatory failure in neuromuscular diseases and other chronic disorders. The uptake of noninvasive positive pressure ventilation has resulted in widespread growth in home ventilation internationally and fewer patients being ventilated invasively. As with many applications of domiciliary medical technology, home ventilatory support has either led or run in parallel with acute hospital applications and has been influenced by medical and societal shifts in the approach to chronic care, the creation of community support teams, a preference of recipients to be treated at home, and economic imperatives. This review summarizes the trends and growing evidence base for ventilatory support outside the hospital.

Nocturnal mechanical ventilation for chronic hypoventilation in patients with neuromuscular and chest wall disorders

BACKGROUND

Chronic alveolar hypoventilation is a common complication of many neuromuscular and chest wall disorders. Long-term nocturnal mechanical ventilation is commonly used to treat it. This is a 2014 update of a review first published in 2000 and previously updated in 2007.

OBJECTIVES

To examine the effects on mortality of nocturnal mechanical ventilation in people with neuromuscular or chest wall disorders. Subsidiary endpoints were to examine the effects of respiratory assistance on improvement of chronic hypoventilation, sleep quality, hospital admissions and quality of life.

SEARCH METHODS

We searched the Cochrane Neuromuscular Disease Group Specialized Register, CENTRAL, MEDLINE and EMBASE on 10 June 2014. We contacted authors of identified trials and other experts in the field.

SELECTION CRITERIA

We searched for quasi-randomised or randomised controlled trials of participants of all ages with neuromuscular or chest wall disorder-related stable chronic hypoventilation of all degrees of severity, receiving any type and any mode of long-term nocturnal mechanical ventilation. The primary outcome measure was one-year mortality and secondary outcomes were unplanned hospital admission, short-term and long-term reversal of hypoventilation-related clinical symptoms and daytime hypercapnia, improvement of lung function and sleep breathing disorders.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methodology to select studies, extract data and assess the risk of bias in included studies.

MAIN RESULTS

The 10 eligible trials included a total of 173 participants. Roughly half of the trials were at low risk of selection, attrition or reporting bias, and almost all were at high risk of performance and detection bias. Four trials reported mortality data in the long term. The pooled risk ratio (RR) of dying was 0.62 (95% confidence interval (CI) 0.42 to 0.91, P value = 0.01) in favour of nocturnal mechanical ventilation compared to spontaneous breathing. There was considerable and significant heterogeneity between the trials, possibly related to differences between the study populations. Information on unplanned hospitalisation was available from two studies. The corresponding pooled RR was 0.25 (95% CI 0.08 to 0.82, P value = 0.02) in favour of nocturnal mechanical ventilation. For most of the outcome measures there was no significant long-term difference between nocturnal mechanical ventilation and no ventilation. Most of the secondary outcomes were not assessed in the eligible trials. Three out of the 10 trials, accounting for 39 participants, two with a cross-over design and one with two parallel groups, compared volume- and pressure-cycled non-invasive mechanical ventilation in the short term. From the only trial (16 participants) on parallel groups, there was no difference in mortality (one death in each arm) between volume- and pressure-cycled mechanical ventilation. Data from the two cross-over trials suggested that compared with pressure-cycled ventilation, volume-cycled ventilation was associated with less sleep time spent with an arterial oxygen saturation below 90% (mean difference (MD) 6.83 minutes, 95% CI 4.68 to 8.98, P value = 0.00001) and a lower apnoea-hypopnoea (per sleep hour) index (MD -0.65, 95% CI -0.84 to -0.46, P value = 0.00001). We found no study that compared invasive and non-invasive mechanical ventilation or intermittent positive pressure versus negative pressure ventilation.

AUTHORS' CONCLUSIONS

Current evidence about the therapeutic benefit of mechanical ventilation is of very low quality, but is consistent, suggesting alleviation of the symptoms of chronic hypoventilation in the short term. In four small studies, survival was prolonged and unplanned hospitalisation was reduced, mainly in participants with motor neuron diseases. With the exception of motor neuron disease and Duchenne muscular dystrophy, for which the natural history supports the survival benefit of mechanical ventilation against no ventilation, further larger randomised trials should assess the long-term benefit of different types and modes of nocturnal mechanical ventilation on quality of life, morbidity and mortality, and its cost-benefit ratio in neuromuscular and chest wall diseases.

Noninvasive ventilation in adults with acute respiratory distress: a primer for the clinician

Noninvasive ventilation (NIV) has become an integral part of critical care management. Despite > 2 decades of experience, it is relatively underused, with general utilization reported as a little over 10% in a recent international survey. Lack of training, knowledge, equipment, and experience with NIV may account for its slow adoption. Patient selection, staff training and experience, and prompt recognition of ineffective NIV are important components to successful application of NIV. Noninvasive ventilation does have a learning curve that may be steep for some institutions but must be mastered if the procedure is to become a successful institutional component of care. Patients with acute respiratory failure due to chronic obstructive pulmonary disease or congestive heart failure are ideal candidates for NIV, and optimal efficacy in associated conditions is often linked to these 2 conditions. Technical issues and written guidelines are addressed, including details of an adequate trial of therapy as well as criteria for intubation. Attention to these elements should increase the success rate of NIV, which in turn should increase its general use.

UK physicians’ attitudes and practices in long-term non-invasive ventilation of Duchenne Muscular Dystrophy

Previous studies have shown that long-term non-invasive ventilation (NIV) is not always routinely offered by all physicians in Duchenne Muscular Dystrophy (DMD), despite evidence that this treatment improves quality of life and survival. This study examined UK physicians' practices related to respiratory follow-up and DMD ventilation. A mailed questionnaire was used. Thirty-eight of the 59 (64%) UK physicians identified via the Muscular Dystrophy Campaign (MDC) responded. Eighty-one per cent of respondents felt ethically obliged to discuss NIV with families while 13% believed that NIV results in poor quality of life. Forty-seven per cent of physicians discuss in-depth the use of NIV when the patient is in respiratory failure. Eighty-four ventilated DMD patients in the respondents' practice use NIV (via Bi-Pap Nasal mask). Nearly 66% of physicians do not consider the public cost to be an impediment to offering NIV, despite significant problems with resources' allocation in their area. While the majority of UK physicians have comparable attitudes and practices regarding NIV, the questionnaire highlighted that not all specialists were aware of the existence of consensus guidelines regarding respiratory monitoring. In addition, different practices of disclosure of life-prolonging ventilation options were used by different physicians. Seventy-one per cent of physicians wished for national consensus guidelines for different DMD age groups.

Chronic respiratory failure and neuromuscular disease

The outlook for children with respiratory complications of neuromuscular disease has improved significantly in the past 15 years. This has been the result of many advances in clinical care, including improved monitoring of lung function and hypoventilation during sleep; coordinated respiratory care by experienced physicians with access to specialized respiratory services, especially physiotherapy; and, most importantly, the widespread introduction of noninvasive ventilation.

A ventilator requirement index

OBJECTIVE

To determine the efficacy of vital capacity (VC) and a proposed ventilator requirement index (VRI) for justifying ventilator prescription and use for patients with neuromuscular/chest wall diseases (NMD).

DESIGN

Prospective observational study in which 319 patients with NMD, including 187 ventilator users, were separated into four groups: (1) asymptomatic, (2) abnormal specific screening factors and/or symptomatic, (3) ventilator use 8-20 hrs/day, and (4) >20 hrs/day of ventilator use. The VRI was defined as 60 x Ti/(Ttot)2 x (Vt/VC) x RR, where Ti = inspiratory time of one breath (secs), Ttot = total time of one breath (secs), Vt = tidal volume (ml) at rest, VC = vital capacity (ml), and RR = respiratory rate.

RESULTS

The overall analysis of variance F-tests and post hoc pairwise contrasts were significant (P < 0.001) for differences in the VC and VRI across groups. Thus, VC and VRI are independent predictors of group membership. Satisfying VC or VRI criteria signaled the highest number of patients benefiting from ventilator use.

CONCLUSIONS

The prescription of one or two ventilators can be justified by both VC and VRI, with the combination being most sensitive.

Nocturnal mechanical ventilation for chronic hypoventilation in patients with neuromuscular and chest wall disorders

BACKGROUND

Chronic alveolar hypoventilation is a common complication of many neuromuscular and chest wall disorders. Long-term nocturnal mechanical ventilation is increasingly used to treat it.

OBJECTIVES

To examine the efficacy of nocturnal mechanical ventilation in relieving hypoventilation related symptoms and in prolonging survival in people with neuromuscular or chest wall disorders.

SEARCH STRATEGY

We searched the Cochrane Neuromuscular Disease Group Trials Register, MEDLINE (from January 1966 to June 2006), and EMBASE (from January 1980 to June 2006) for randomised trials and contacted authors of trials and other experts in the field.

SELECTION CRITERIA

We searched for quasi-randomised or randomised controlled trials of participants with neuromuscular or chest wall disorder-related stable chronic hypoventilation of all ages and all degrees of severity, receiving any type and any mode of nocturnal mechanical ventilation. The primary outcome measure was short-term and long-term reversal of hypoventilation related clinical symptoms and secondary outcomes were unplanned hospital admission, one year mortality, short-term and long-term reversal of daytime hypercapnia, improvement of lung function and sleep breathing disorders.

DATA COLLECTION AND ANALYSIS

We identified eight randomised trials.

MAIN RESULTS

The eight eligible trials included a total of 144 participants. The relative risk of 'no improvement of hypoventilation related clinical symptoms' in the short-term following nocturnal mechanical ventilation was available in only one trial with 10 participants and was not significant, 0.09 (95% confidence interval (CI) 0.01 to 1.31). The relative risk of 'no reversal of daytime hypercapnia' in the short-term following nocturnal ventilation was significant and favoured treatment, 0.37 (95% CI 0.20 to 0.65). The weighted mean difference of nocturnal mean oxygen saturation was 5.45% (95% CI 1.47 to 9.44) more improvement in participants treated with nocturnal mechanical ventilation. For most of the outcome measures there was no significant long-term difference between nocturnal mechanical ventilation and no ventilation. However, the estimated risk of death based on three studies was reduced following nocturnal ventilation, 0.62 (95% CI 0.42 to 0.91). There was considerable and significant heterogeneity between the trials possibly related to differences between the study populations. Most of the secondary outcomes were not assessed in the eligible trials. Data from two crossover trials suggested no evidence for a difference in reversal of daytime hypercapnia and sleep study parameters between volume-cycled and pressure-cycled ventilation. No data could be summarised for the comparisons between invasive and non-invasive mechanical ventilation or between intermittent positive pressure and negative pressure ventilation.

AUTHORS' CONCLUSIONS

Current evidence about the therapeutic benefit of mechanical ventilation is weak, but consistent, suggesting alleviation of the symptoms of chronic hypoventilation in the short-term. In three small studies survival was prolonged mainly in participants with motor neuron diseases. With the exception of motor neuron disease, further larger randomised trials are needed to confirm long-term beneficial effects of nocturnal mechanical ventilation on quality of life, morbidity and mortality, to assess its cost-benefit ratio in neuromuscular and chest wall diseases and to compare the different types and modes of ventilation.

Chronic respiratory failure in patients with neuromuscular diseases: diagnosis and treatment

Neuromuscular diseases affect alveolar air exchange and therefore cause chronic respiratory failure. The onset of respiratory failure can be acute, as in traumas, or progressive (slow or rapid), as in amyotrophic lateral sclerosis, muscular dystrophies, diseases of the myoneural junction, etc. Respiratory muscle impairment also affects cough efficiency and, according to the current knowledge regarding the type of treatment available in Brazil to these patients, it can be said that the high rates of morbidity and mortality in these individuals are more often related to the fact that they cough inefficiently rather than to the fact that they ventilate poorly. In this review, with the objective of presenting the options of devices available to support and substitute for natural ventilation in patients with neuromuscular diseases, we have compiled a brief history of the evolution of orthopedic braces and prostheses used to aid respiration since the end of the 19th century. In addition, we highlight the elements that are fundamental to the diagnosis of alveolar hypoventilation and of failure of the protective cough mechanism: taking of a clinical history; determination of peak cough flow; measurement of maximal inspiratory and expiratory pressures; spirometry in two positions (sitting and supine); pulse oximetry; capnography; and polysomnography. Furthermore, the threshold values available in the literature for the use of nocturnal ventilatory support and for the extension of this support through the daytime period are presented. Moreover, the maneuvers used to increase cough efficiency, as well as the proper timing of their introduction, are discussed.

Recent Advances in Respiratory Care for Neuromuscular Disease

The impact of ventilatory support on the natural history of neuromuscular disease (NMD) has become clearer over the last 2 decades as techniques have been more widely applied. Noninvasive ventilation (NIV) allows some patients with nonprogressive pathology to live to nearly normal life expectancy, extends survival by many years in patients with other conditions (eg, Duchenne muscular dystrophy), and in those patients with rapidly deteriorating disease (eg, amyotrophic lateral sclerosis) survival may be increased, but symptoms can be palliated even if mortality is not reduced. A growing number of children with NMD are surviving to adulthood with the aid of ventilatory support. The combination of NIV with cough-assist techniques decreases pulmonary morbidity and hospital admissions. Trials have confirmed that NIV works in part by enhancing chemosensitivity, and in patients with many different neuromuscular conditions the most effective time to introduce NIV is when symptomatic sleep-disordered breathing develops.

Baclofen pump intervention for spasticity affecting pulmonary function

INTRODUCTION

Muscle spasticity may adversely affect pulmonary function after spinal cord injury (SCI). However, there is limited information regarding the treatment of spasticity as a determinant of pulmonary function. This study presents the case of a man with C4 tetraplegia who had severe spasticity and difficulty weaning from ventilatory support.

METHODS

Case presentation.

RESULTS

Severe spasticity likely contributed to respiratory compromise in this patient. Successful and rapid weaning from the ventilator occurred within 3 weeks of baclofen pump placement.

CONCLUSIONS

Randomized clinical trials among SCI patients with significant spasticity are needed to determine whether intervention with a baclofen pump facilitates earlier ventilatory weaning.

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.

Noninvasive mechanical ventilation for post acute care

The increasing use of NPPV in both acute and chronic settings has added to ventilator options in the post acute setting. Some patients start NPPV during their acute presentation and continue use during their post acute stay. Others are difficult to wean from invasive mechanical ventilation, and, if selected carefully, can be extubated and weaned using NPPV. Still others may initiate NPPV in the post acute setting with the anticipation of long-term use. In any care settings, principles of patient selection and management in monitoring practices overlap considerably. Noninvasive ventilation has been shown to reduce morbidity, mortality, and hospital stay in the acute setting for selected patients, and almost certainly prolongs survival for patients with restrictive thoracic disorders in the chronic setting. Although efficacy studies have not been performed in the post acute setting, it is reasonable to anticipate that appropriate use of NPPV will yield similar benefits. Accordingly, clinicians working in the post acute setting must acquire skill and experience in the proper application of NPPV to optimally manage the increasing number of patients treated with NPPV in this expanding arena.

Nocturnal mechanical ventilation for chronic hypoventilation in patients with neuromuscular and chest wall disorders

BACKGROUND

Chronic alveolar hypoventilation is a common complication of many neuromuscular and chest wall disorders. Long term nocturnal mechanical ventilation is used to treat an increasing number of patients.

OBJECTIVES

To examine the efficacy of nocturnal mechanical ventilation in relieving hypoventilation related symptoms in patients with neuromuscular or chest wall disorders.

SEARCH STRATEGY

Search of the Cochrane Neuromuscular Disease Group register for randomized trials and enquiry from authors of trials and other experts in the field.

SELECTION CRITERIA

Types of studies: quasi-randomized or randomized controlled trials

TYPES OF PARTICIPANTS

patients with neuromuscular or chest wall disorder-related stable chronic hypoventilation of all ages and all degrees of severity. Types of interventions: any type and any mode of nocturnal mechanical ventilation. Types of outcome measures: Primary: short term and long term reversal of hypoventilation related clinical symptoms Secondary: unplanned hospital admission rate, one year mortality, short term and long term reversal of day time hypercapnia, improvement of lung function and improvement of sleep breathing disorders.

DATA COLLECTION AND ANALYSIS

We identified four randomized trials. One author extracted the data and another checked them. Individual data were available from the authors of the largest study.

MAIN RESULTS

The four eligible trials included a total of 51 patients. The risk difference (proportion of patients) of no improvement of hypoventilation related clinical symptoms in the short term following nocturnal mechanical ventilation was significant and favoured treatment, -0.417 (95% CI -0.639 to -0.194). However, there was significant heterogeneity across the studies (p<0.001). Similarly, the risk difference of no reversal of day time hypercapnia in the short term following nocturnal ventilation was significant and favoured treatment, -0.635 (95% CI -0.874 to -0.396). The weighted mean difference of nocturnal mean oxygen saturation percent was 5.5 (95% CI 1.5 to 9.4) more improvement in patients treated with nocturnal mechanical ventilation. For the primary and most of the secondary outcome measures there was no significant difference between nocturnal mechanical ventilation and no ventilation in the long term, except for one-year mortality. Indeed, the risk difference of death one year following implementation of nocturnal mechanical ventilation was significant and favoured treatment, -0.259 (95% CI -0.478 to -0. 041). However, there was significant heterogeneity across the studies (p<0.001). Most of the secondary outcomes were not assessed in the eligible trials. No data could be summarised for the comparisons between invasive and non-invasive mechanical ventilation, between intermittent positive pressure and negative pressure ventilation, and between volume-cycled and pressure-cycled ventilation.

REVIEWER'S CONCLUSIONS

Current evidence about the therapeutic benefit of mechanical ventilation is weak, but consistent, suggesting alleviation of the symptoms of chronic hypoventilation in the short term, and in two small studies survival was prolonged. Mechanical ventilation should be offered as a therapeutic option to patients with chronic hypoventilation due to neuromuscular diseases. Further larger randomized trials are needed to confirm long term beneficial effects of nocturnal mechanical ventilation on quality of life, morbidity and mortality, to assess its cost-benefit ratio, and to compare the different types and modes of ventilation.

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

STUDY OBJECTIVES

Previous studies have shown the acute effects of noninvasive positive pressure ventilation (NPPV) in chronic respiratory failure; however, information on the chronic effects of NPPV is limited. We examined the acute and chronic effects of NPPV on gas exchange, functional status, and respiratory mechanics in patients with chronic respiratory failure related to restrictive ventilatory disorders or COPD.

DESIGN

Descriptive analysis of prospectively collected clinical data.

SETTING

Inpatient noninvasive respiratory care unit and outpatient clinic of university hospital.

PATIENTS

Forty patients with chronic respiratory failure (20 with severe COPD and 20 with restrictive ventilatory disorders).

INTERVENTIONS AND MEASUREMENTS

All patients were admitted to a noninvasive respiratory care unit for 20 +/- 3 days for inpatient evaluation consisting of medical treatment, rehabilitation, and NPPV evaluation and instruction. NPPV was titrated via a ventilatory support system (BiPAP; Respironics Inc; Monroeville, PA) or a portable volume ventilator (PLV 102; Lifecare, Inc; Boulder, CO) to achieve a > or = 20% increase in baseline minute ventilation while monitoring gas exchange, expired volume, and clinical evidence of a decrease in the patient's work of breathing.

RESULTS

The patients' mean age (+/- SD) was 65 +/- 9.7 years, and there was a 3:1 female:male predominance. In the noninvasive respiratory care unit, 36 patients used NPPV for 7.31 +/- 0.26 h/night. Four patients (three with COPD, one with restrictive disorder) withdrew from the study during the 3-week inpatient stay because they could not tolerate NPPV. Six patients (5 with COPD, 1 with restrictive disorder) used a portable volume ventilator and 34 patients used BiPAP (15 with COPD, 19 with restrictive disorders). At discharge, compared with at admission, daytime PaO2/fraction of inspired oxygen (FIO2) increased (327 +/- 10 vs 283 +/- 13 mm Hg; p = 0.01), PaCO2 was reduced (52 +/- 2 vs 67 +/- 3 mm Hg; p = 0.0001), and functional score increased (4.76 +/- 1.16 vs 2.7 +/- 1.64 arbitrary units (AUs); p < 0.01). Six months after discharge, improvements in PaO2/FIO2 (317 +/- 10 vs 283 +/- 13; p = 0.05), PaCO2 (52 +/- 2 vs 67 +/- 3 mm Hg; p = 0.0001), and functional score (5.66 +/- 0.41 vs 2.7 +/- 0.3 AUs; p < 0.001) were maintained compared with admission values. FVC, FEV1, and maximum inspired and expired mouth pressures were unchanged before and after long-term NPPV. Ten patients (7 with COPD, 3 with restrictive disorders) discontinued NPPV at 6 months, and 3 progressed to tracheostomy. The remaining 26 patients continued to use NPPV at the 6-month follow-up. They claimed to use NPPV for 7.23 +/- 0.24 h/night, but logged metered use was 4.5 +/- 0.58 h/night. Problems that required adjustment in either the mask (36%) or ventilator source (36%) included mask leaks (43%), skin irritation (22%), rhinitis (13%), aerophagia (13%), and discomfort from mask headgear (7%).

CONCLUSION

NPPV acutely and chronically improves gas exchange and functional status in patients with chronic respiratory failure, but a significant number of patients do not tolerate NPPV on a chronic basis. Comprehensive follow-up is required to correct problems with NPPV and ensure optimal patient compliance.

Newer ventilatory strategies

Over the past year a large number of innovations in mechanical ventilation have been evaluated. Three of the most exciting are non-invasive positive pressure ventilation, tracheal gas insufflation and partial liquid ventilation. Non-invasive positive pressure ventilation is now clearly a standard of care in the management of an acute exacerbation of chronic obstructive pulmonary disease. In addition, its use in other clinical settings is being actively explored. Tracheal gas insufflation appears to be a useful adjunct to mechanical ventilation for the management of carbon dioxide but requires manufacturer-designed devices for safe application. The effects of partial liquid ventilation on lung injury have been more clearly defined in the past year as well as approaches to provide gas ventilation during partial liquid ventilation.

Noninvasive ventilation in neuromuscular disease

The treatment of respiratory failure in patients who have NMD continues to be an evolving process. Negative-pressure ventilation, once prominent in the 1940s and 1950s, gave way to intermittent positive-pressure ventilation with tracheostomy or endotracheal tubes in the 1960s. Now there is a resurgence of noninvasive ventilation, brought about by innovative modes of positive pressure delivered through nasal and facial masks. Although frequently relegated to second-line choices, negative-pressure devices still offer a practical treatment alternative as patient preference still plays a role in selecting a proper mode of ventilation. Studies have shown that noninvasive ventilation can prevent or reverse respiratory failure and improve quality of life and longevity. Despite the seemingly widespread acceptance of noninvasive ventilation in the treatment of respiratory failure, physicians still appear reluctant to use ventilatory assistance in the neuromuscular arena. In 1985, a survey found that respiratory support systems were utilized routinely in only 33% of the 132 responding Muscular Dystrophy Association (MDA) clinics. Bach recently surveyed 273 MDA clinic directors and co-directors from 167 clinics, to evaluate their current use of mechanical ventilation. Ventilatory assistance was recommended and used electively in only 43 (26%) of the 167 clinics. Furthermore, it was the policy in 68 of the clinics to discourage the use of mechanical ventilation. Even more importantly, only 2 physicians who discouraged the use of mechanical ventilation were familiar with the newest noninvasive methods of ventilatory support. Sadly, although our methodologies in the treatment of respiratory failure continue to improve, physician practice has lagged behind. Physicians who treat patients who have NMD need to become cognizant of these new techniques and incorporate them into their present therapeutic armamentarium.

The management of neuromuscular ventilatory failure

All patients with respiratory impairment have either primarily ventilatory or primarily oxygenation impairment. Patients with neuromuscular conditions fall into the former category but are all too often managed as though they had the latter with oxygen therapy, bronchodilators, chest physical therapy, intermittent positive pressure breathing, and so on. This approach can only hasten respiratory failure and management by tracheostomy-However, it has been reported that with the use of noninvasive respiratory muscle aids, respiratory morbidity and mortality can be prevented for most patients with neuromuscular disease without resort to tracheostomy or even hospitalization.

Noninvasive ventilation via bilevel positive airway pressure support in pediatric practice

OBJECTIVE

To evaluate the efficacy of bilevel positive airway pressure support in critically ill children with underlying medical conditions.

DESIGN

Prospective, clinical study.

SETTING

Pediatric intensive care unit (ICU).

PATIENTS

Thirty-four patients (6 mos to 20 yrs, mean 11.06 +/- 0.9 yrs) with impending respiratory failure were enrolled in the study. All patients required airway or oxygenation/ventilation support (awake or asleep) and required admission to our pediatric ICU. Each patient served as his or her own control. Exclusion criteria were absent cough or gag reflex, multiple organ system failure, age of <6 mos, vocal cord paralysis, and noncooperation with nasal mask.

INTERVENTIONS

Bilevel positive airway pressure support ventilation.

MEASUREMENTS AND MAIN RESULTS

Thirty-four patients with 35 episodes of respiratory insufficiency requiring airway support or oxygenation/ventilatory support were treated with bilevel positive airway pressure support ventilation. Dyspnea score decreased at least two deviations in all patients; dyspnea score decreased five deviations in 67% of patients. Resting heart rate decreased from 126 +/- 3.2 to 102 +/- 3.2 beats/min (p < .001), respiratory rate decreased from 39 +/- 3 to 25 +/- 1 breaths/min (p < .004), bicarbonate concentrations decreased from 30.0 +/- 1.0 to 24.0 +/- 0.7 mmol/L (p < .01), and room air saturation increased from 85 +/- 2% to 97 +/- 1%. Bilevel positive airway pressure support ventilation failure was characterized by an inability to stabilize progression of respiratory failure and the subsequent placement of an artificial airway. Three patients required placement of an artificial airway.

CONCLUSIONS

A decrease in respiratory rate, heart rate, and dyspnea score and an improvement in oxygenation were noted in >90% of patients studied, resulting in only an 8% frequency of intubation. The efficacy of bilevel positive airway pressure support ventilation in selected groups of patients indicates the need to include this form of noninvasive pressure support ventilation in the care offered by pediatric ICUs.

Long-term efficiency of home nasal mask ventilation in patients with diffuse bronchiectasis and severe chronic respiratory failure: a case-control study

The aim of this study was to evaluate long-term efficacy and tolerance of nasal mask ventilation (NMV) in a comparative case-control study. Fourteen patients with diffuse bronchiectasis and severe chronic respiratory failure (CRF), treated by long-term oxygen-therapy (LTO) and NMV, were case matched with 14 patients with diffuse bronchiectasis and severe CRF treated with only LTO. Patients and control subjects were compared based on the following parameters: blood gases, FEV1, vital capacity, hospitalizations, and survival. Symptoms, Karnofsky function score, and clinical evolution were also monitored in patients. Three subgroups may be identified according to outcome: two early deaths (subgroup 1), six patients with initial improvement and subsequent deterioration (subgroup 2), and six patients whose conditions remained improved for >2 years (subgroup 3). PaO2 decrease slope was slighter in this last subgroup than subgroup 2. The days of hospitalization were significantly reduced after institution of NMV in the patient group. Comparison between patients and control subjects did not show any difference on PaO2 evolution and on the overall median survival (46 and 40 months in NMV and control group, respectively). Long-term tolerance and compliance remained satisfactory for 11 patients. These results suggest that NMV is feasible as a long-term home treatment in patients with diffuse bronchiectasis. Although our results may have failed to prove a long-term efficiency on the course of blood gases and survival, a beneficial effect is observed with reduction of hospitalizations and improvement of functional status. This study warrants further investigation, in a prospective series, with a larger number of patients.

Performance characteristics of bilevel pressure ventilators: a lung model study

Bilevel pressure ventilators are being used increasingly to provide noninvasive ventilatory support in the management of obstructive sleep apnea, chronic ventilatory failure, and acute respiratory failure. However, the ability of these ventilators to respond to inspiratory demand without imposing expiratory loads has not been evaluated extensively. We evaluated the performance of nine bilevel pressure ventilators in a lung model, as compared with the Nellcor Puritan-Bennett 7200ae adult critical care ventilator. All ventilators were set to provide pressure support ventilation (PSV) and positive end-expiratory pressure (PEEP) at a rate of 10 breaths/min with an inspiratory time of 1.0 s. Simulated pleural pressure, airway pressure, and flow at airway opening were continuously monitored. We studied the effects of three PSV levels (5, 10, and 15 cm H2O) with 5 cm H2O PEEP at two lung compliances (50 and 80 mL/cm H2O) and four peak inspiratory flow demands (20, 40, 60, and 80 L/min) on seven dependent variables: inspiratory delay time (D-I), inspiratory trigger pressure (P-I), inspiratory area percent (Area I%), expiratory delay time (D-E), supraplateau expiratory pressure change (P-E), expiratory area (Area E), and ventilator peak flow (VPF). Most ventilators performed as well as or significantly (p<0.05) better than the 7200ae in all studied variables. Compliance did not significantly affect ventilator performance. Increasing inspiratory flow demand significantly (p<0.05) increased D-I, P-I, P-E, and VPF and decreased Area I% with most ventilators. As ventilatory demand increased, D-E and Area E significantly (p<0.05) changed. With some units, D-E and Area E increased, while with others they decreased. Most bilevel pressure ventilators evaluated were able to respond to high ventilatory demands and outperformed the Nellcor Puritan-Bennett 7200ae ventilator.

Home mechanical ventilation for amyotrophic lateral sclerosis: nasal compared to tracheostomy-intermittent positive pressure ventilation

People with amyotrophic lateral sclerosis (ALS) usually die from respiratory failure unless they use mechanical ventilation (MV). Many die of respiratory failure without being adequately informed about the available options, such as MV that can provide symptomatic relief and prolong survival. The traditional method of MV used for persons with ALS has been tracheostomy-intermittent positive pressure ventilation (IPPV). However, the advent of nasal-IPPV has provided a new option for relieving respiratory symptoms and prolonging survival among selected individuals. The ALS Association Data on 75 ALS patients using MV is reviewed. Twenty-five patients used nasal-IPPV, all started electively. Survival with nasal-IPPV ranged from 6 to 64 months for non-bulbar patients, or until the onset of severe bulbar dysfunction when nasal-IPPV no longer was effective. Fifteen of these non-bulbar patients used nasal-IPPV from 20 to 24 h daily; one of these patients used nasal-IPPV continuously for 24 h daily for 24 months. One hundred percent of the users indicated they were glad they chose nasal-IPPV. In contrast, 50 have used tracheostomy-IPPV, usually as a result of emergency hospitalization without advance decision making. Twenty-five patients (50%) lived in a sub-acute skilled nursing facility (SNF) and only 18 of these (72%) were satisfied with their quality of life. Patients using tracheostomy-IPPV with good care are able to live many years: 27 of the 50 (54%) are still living, including one patient who is still living after 14 years of MV. In conclusion, home mechanical ventilation with nasal or tracheostomy-IPPV are options for selected people with ALS. Nasal-IPPV offers may advantages; it was only used when MV was planned and desired. Nasal-IPPV can be used unless bulbar impairment is severe.