In vivo physiologic comparison of two ventilators used for domiciliary ventilation in children with cystic fibrosis

Non-invasive respiratory support in children and young adults with complex medical conditions in pediatric palliative care

OBJECTIVE

Dyspnoea and sleep-disordered breathing (SDB) are common in children with life-limiting conditions but studies on treatment with non-invasive ventilation (NIV) or continuous positive airway pressure (CPAP) are scarce. The aim of the study was to describe children treated with long-term NIV/CPAP within a paediatric palliative care programme in France.

METHODS

Cross-sectional survey on children and young adults with complex medical conditions treated within the French paediatric NIV network with long-term NIV/CPAP. Characteristics of the patients were analysed and patient-related outcome measures of NIV/CPAP benefit were reported.

RESULTS

The data of 50 patients (68% boys), median age 12 (0.4-21) years were analysed. Twenty-three (46%) patients had a disorder of the central nervous system and 5 (10%) a chromosomal anomaly. Thirty-two (64%) patients were treated with NIV and 18 (36%) with CPAP. NIV/CPAP was initiated on an abnormal Apnoea-Hypopnoea Index in 18 (36%) of the patients, an abnormal nocturnal gas exchange alone in 28 (56%), and after an acute respiratory failure in 11 (22%) of the patients. Mean objective NIV/CPAP adherence was 9.3±3.7 hours/night. NIV/CPAP was associated with a decrease in dyspnoea in 60% of patients, an increase in sleep duration in 60% and in sleep quality in 74%, and an improvement in parents' sleep in 40%.

CONCLUSIONS

In children with life-limiting conditions, long-term NIV/CPAP may be associated with relief of dyspnoea, an improvement of SDB and an improvement in parents' sleep.

An overview of noninvasive ventilation in cystic fibrosis

Noninvasive ventilation (NIV) use was initially reported in cystic fibrosis (CF) in 1991 as a bridge to lung transplantation, and over the decades, the use of NIV has increased in the CF population. Individuals with CF are prone to various physiologic changes as lung function worsens, and they benefit from NIV for advanced lung disease. As life expectancy in CF has been increasing due to advances such as highly effective modulator therapy, people with CF may also benefit from NIV for other diagnosis beyond advanced lung disease. NIV can improve gas exchange, quality of sleep, exercise tolerance, and augment airway clearance in CF. CF providers can readily become comfortable with this therapeutic modality. In this review, we will summarize the physiologic basis for NIV use in CF, describe indications for initiation, and discuss how to order and monitor patients on NIV. We will discuss aspects unique to people with CF and the use of NIV, as well as suggestions on how to reduce risks such as infection. We hope that this serves as a resource for CF providers, in particular those who do not have dedicated training in sleep medicine as we all continue to care for the CF patient population.

ERS Statement on pediatric long term noninvasive respiratory support

Long term noninvasive respiratory support, comprising continuous positive airway pressure (CPAP) and noninvasive ventilation (NIV), in children is expanding worldwide, with increasing complexities of children being considered for this type of ventilator support and expanding indications such as palliative care. There have been improvements in equipment and interfaces. Despite growing experience, there are still gaps in a significant number of areas: there is a lack of validated criteria for CPAP/NIV initiation, optimal follow-up and monitoring; weaning and long term benefits have not been evaluated. Therapeutic education of the caregivers and the patient is of paramount importance, as well as continuous support and assistance, in order to achieve optimal adherence. The preservation or improvement of the quality of life of the patient and caregivers should be a concern for all children treated with long term CPAP/NIV. As NIV is a highly specialised treatment, patients are usually managed by an experienced pediatric multidisciplinary team. This Statement written by experts in the field of pediatric long term CPAP/NIV aims to emphasize on the most recent scientific input and should open up to new perspectives and research areas.

Sleep in children and young adults with cystic fibrosis

Large gains have been made in the management of respiratory diseases associated with cystic fibrosis (CF). Initial studies evaluating sleep issues in CF focused on respiratory problems of nocturnal hypoxia, alveolar hypoventilation and risk of airway obstruction from nasal polyps with treatment evaluations including long term oxygen therapy or noninvasive ventilation in case of nocturnal hypercapnia. More recent studies include patients whose lung function is better preserved, and have permitted more focus on sleep patterns and sleep quality. This literature identified that reduced sleep duration and poor sleep quality are common and may be explained by chronic pain and cough, frequent stools, gastro-oesophageal reflux, nasal obstruction or sinusitis, and drugs such as corticosteroids or beta-agonists. In the teenage years, poor sleep hygiene, sleep debt and poor sleep quality are associated with depression, poor academic performance, less physical activity, and a decrease in quality of life. Restless leg syndrome also seems to be common in adult patients with CF. These sleep problems seem more important in patients with a low lung function but may also be observed in patients with preserved lung function. The consequences of poor sleep may potentially exaggerate the multi-organ morbidity of CF, such as pain, inflammation, susceptibility to infection, and glucose intolerance, but these aspects are largely under-evaluated. Sleep should be evaluated on a routine basis in CF and prospective studies assessing the benefits of interventions aiming at improving sleep duration and sleep quality urgently needed.

Non-invasive Ventilation for Children With Chronic Lung Disease

Advances in medical care and supportive care options have contributed to the survival of children with complex disorders, including children with chronic lung disease. By delivering a positive pressure or a volume during the patient's inspiration, NIV is able to reverse nocturnal alveolar hypoventilation in patients who experience hypoventilation during sleep, such as patients with chronic lung disease. Bronchopulmonary dysplasia (BPD) is a common complication of prematurity, and despite significant advances in neonatal care over recent decades its incidence has not diminished. Most affected infants have mild disease and require a short period of oxygen supplementation or respiratory support. However, severely affected infants can become dependent on positive pressure support for a prolonged period. In case of established severe BPD, respiratory support with non-invasive or invasive positive pressure ventilation is required. Patients with cystic fibrosis (CF) and advanced lung disease develop hypoxaemia and hypercapnia during sleep and hypoventilation during sleep usually predates daytime hypercapnia. Hypoxaemia and hypercapnia indicates poor prognosis and prompts referral for lung transplantation. The prevention of respiratory failure during sleep in CF may prolong survival. Long-term oxygen therapy has not been shown to improve survival in people with CF. A Cochrane review on the use NIV in CF concluded that NIV in combination with oxygen therapy improves gas exchange during sleep to a greater extent than oxygen therapy alone in people with moderate to severe CF lung disease. Uncontrolled, non-randomized studies suggest survival benefit with NIV in addition to being an effective bridge to transplantation. Complications of NIV relate mainly to prolonged use of a face or nasal mask which can lead to skin trauma, and neurodevelopmental delay by acting as a physical barrier to social interaction. Another associated risk is pulmonary aspiration caused by vomiting whilst wearing a face mask. Adherence to NIV is one of the major barriers to treatment in children. This article will review the current evidence for indications, adverse effects and long term follow up including adherence to NIV in children with chronic lung disease.

Non-invasive ventilation for cystic fibrosis

BACKGROUND

Non-invasive ventilation may be a means to temporarily reverse or slow the progression of respiratory failure in cystic fibrosis by providing ventilatory support and avoiding tracheal intubation. Using non-invasive ventilation, in the appropriate situation or individuals, can improve lung mechanics through increasing airflow and gas exchange and decreasing the work of breathing. Non-invasive ventilation thus acts as an external respiratory muscle. This is an update of a previously published review.

OBJECTIVES

To compare the effect of non-invasive ventilation versus no non-invasive ventilation in people with cystic fibrosis for airway clearance, during sleep and during exercise.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches, handsearching relevant journals and abstract books of conference proceedings. We searched the reference lists of each trial for additional publications possibly containing other trials.Most recent search: 08 August 2016.

SELECTION CRITERIA

Randomised controlled trials comparing a form of pressure preset or volume preset non-invasive ventilation to no non-invasive ventilation used for airway clearance or during sleep or exercise in people with acute or chronic respiratory failure in cystic fibrosis.

DATA COLLECTION AND ANALYSIS

Three reviewers independently assessed trials for inclusion criteria and methodological quality, and extracted data.

MAIN RESULTS

Ten trials met the inclusion criteria with a total of 191 participants. Seven trials evaluated single treatment sessions, one evaluated a two-week intervention, one evaluated a six-week intervention and one a three-month intervention. It is only possible to blind trials of airway clearance and overnight ventilatory support to the outcome assessors. In most of the trials we judged there was an unclear risk of bias with regards to blinding due to inadequate descriptions. The six-week trial was the only one judged to have a low risk of bias for all other domains. One single intervention trial had a low risk of bias for the randomisation procedure with the remaining trials judged to have an unclear risk of bias. Most trials had a low risk of bias with regard to incomplete outcome data and selective reporting.Six trials (151 participants) evaluated non-invasive ventilation for airway clearance compared with an alternative chest physiotherapy method such as the active cycle of breathing techniques or positive expiratory pressure. Three trials used nasal masks, one used a nasal mask or mouthpiece and one trial used a face mask and in one trial it is unclear. Three of the trials reported on one of the review's primary outcome measures (quality of life). Results for the reviews secondary outcomes showed that airway clearance may be easier with non-invasive ventilation and people with cystic fibrosis may prefer it. We were unable to find any evidence that non-invasive ventilation increases sputum expectoration, but it did improve some lung function parameters.Three trials (27 participants) evaluated non-invasive ventilation for overnight ventilatory support compared to oxygen or room air using nasal masks (two trials) and nasal masks or full face masks (one trial). Trials reported on two of the review's primary outcomes (quality of life and symptoms of sleep-disordered breathing). Results for the reviews secondary outcome measures showed that they measured lung function, gas exchange, adherence to treatment and preference, and nocturnal transcutaneous carbon dioxide. Due to the small numbers of participants and statistical issues, there were discrepancies in the results between the RevMan and the original trial analyses. No clear differences were found between non-invasive ventilation compared with oxygen or room air except for exercise performance, which significantly improved with non-invasive ventilation compared to room air over six weeks.One trial (13 participants) evaluated non-invasive ventilation on exercise capacity (interface used was unclear) and did not reported on any of the review's primary outcomes. The trial found no clear differences between non-invasive ventilation compared to no non-invasive ventilation for any of our outcomes.Three trials reported on adverse effects. One trial, evaluating non-invasive ventilation for airway clearance, reported that a participant withdrew at the start of the trial due to pain on respiratory muscle testing. One trial evaluating non-invasive ventilation for overnight support reported that one participant could not tolerate an increase in inspiratory positive airway pressure. A second trial evaluating non-invasive ventilation in this setting reported that one participant did not tolerate the non-invasive ventilation mask, one participant developed a pneumothorax when breathing room air and two participants experienced aerophagia which resolved when inspiratory positive airway pressure was decreased.

AUTHORS' CONCLUSIONS

Non-invasive ventilation may be a useful adjunct to other airway clearance techniques, particularly in people with cystic fibrosis who have difficulty expectorating sputum. Non-invasive ventilation, used in addition to oxygen, may improve gas exchange during sleep to a greater extent than oxygen therapy alone in moderate to severe disease. The effect of NIV on exercise is unclear. These benefits of non-invasive ventilation have largely been demonstrated in single treatment sessions with small numbers of participants. The impact of this therapy on pulmonary exacerbations and disease progression remain unclear. There is a need for long-term randomised controlled trials which are adequately powered to determine the clinical effects of non-invasive ventilation in cystic fibrosis airway clearance and exercise.

Improvement of the trigger of a ventilator for non-invasive ventilation in children: bench and clinical study

BACKGROUND AND AIMS

Even though numerous ventilators are licensed for a use in children, very few have been specifically developed for this age range. Therefore, home ventilators may not be able to adequately synchronize with the child's respiratory effort, and the inspiratory triggers (ITs) of assist modes are not always appropriate for children. The aim of the study was to test the improvement of the IT of a ventilator on a pediatric bench and in pediatric patients.

METHODS

A classical IT (ITc) and an improved IT [non-invasive ventilation (NIV) + IT] were tested on a bench with six pediatric profiles and in six young patients (mean age 14.1 ± 2.7 years old) requiring long-term NIV.

RESULTS

On the bench, trigger time delays (ΔT) and trigger pressures (ΔP) were reduced with the NIV + IT as compared with the ITc (ΔT: 0.481 ± 0.332 vs 0.079 ± 0.022 s for ITc and NIV + IT, respectively, P = 0.027; ΔP: -1.40 ± 0.70 vs -0.42 ± 0.28 cmH2 O for ITc and NIV + IT, respectively, P = 0.046). The clinical study confirmed the decrease in ΔT (0.267 ± 0.061 vs 0.178 ± 0.074 s for ITc and NIV + IT, respectively, P = 0.024) and ΔP (-0.68 ± 0.26 vs -0.39 ± 0.11 cmH2 O for ITc and NIV + IT, respectively, P = 0.030).

CONCLUSIONS

The sensitivity of the IT of a ventilator can be improved for pediatric use. The improvements observed on the bench study were confirmed in pediatric patients.

Patient-controlled positive end-expiratory pressure with neuromuscular disease: effect on speech in patients with tracheostomy and mechanical ventilation support

OBJECTIVE

Communication is a major issue for patients with tracheostomy who are supported by mechanical ventilation. The use of positive end-expiratory pressure (PEEP) may restore speech during expiration; however, the optimal PEEP level for speech may vary individually. We aimed to improve speech quality with an individually adjusted PEEP level delivered under the patient's control to ensure optimal respiratory comfort.

METHODS

Optimal PEEP level (PEEPeff), defined as the PEEP level that allows complete expiration through the upper airways, was determined for 12 patients with neuromuscular disease who are supported by mechanical ventilation. Speech and respiratory parameters were studied without PEEP, with PEEPeff, and for an intermediate PEEP level. Flow and airway pressure were measured. Microphone speech recordings were subjected to both quantitative and qualitative assessments of speech, including an intelligibility score, a perceptual score, and an evaluation of prosody determined by two speech therapists blinded to PEEP condition.

RESULTS

Text reading time, phonation flow, use of the respiratory cycle for phonation, and speech comfort significantly improved with increasing PEEP, whereas qualitative parameters remained unchanged. This resulted mostly from the increase of the expiratory volume through the upper airways available for speech for all patients combined, with a rise in respiratory rate for nine patients. Respiratory comfort remained stable despite high levels of PEEPeff (median, 10.0 cm H2O; interquartile range, 9.5-12.0 cm H₂O).

CONCLUSIONS

Patient-controlled PEEP allowed for the use of high levels of PEEP with good respiratory tolerance and significant improvement in speech (enabling phonation during the entire respiratory cycle in most patients). The device studied could be implemented in home ventilators to improve speech and, therefore, autonomy of patients with tracheostomy.

TRIAL REGISTRY

ClinicalTrials.gov; No.: NCT01479959; URL: clinicaltrials.gov.

Continuous positive airway pressure titration in infants with severe upper airway obstruction or bronchopulmonary dysplasia

INTRODUCTION

Noninvasive continuous positive airway pressure (CPAP) is recognized as an effective treatment for severe airway obstruction in young children. The aim of the present study was to compare a clinical setting with a physiological setting of noninvasive CPAP in infants with nocturnal alveolar hypoventilation due to severe upper airway obstruction (UAO) or bronchopulmonary dysplasia (BPD).

METHODS

The breathing pattern and respiratory muscle output of all consecutive infants due to start CPAP in our noninvasive ventilation unit were retrospectively analysed. CPAP set on clinical noninvasive parameters (clinical CPAP) was compared to CPAP set on the normalization or the maximal reduction of the oesophageal pressure (Poes) and transdiaphragmatic pressure (Pdi) swings (physiological CPAP). Expiratory gastric pressure (Pgas) swing was measured.

RESULTS

The data of 12 infants (mean age 10 ± 8 mo) with UAO (n = 7) or BPD (n = 5) were gathered. The mean clinical CPAP (8 ± 2 cmH₂O) was associated with a significant decrease in Poes and Pdi swings. Indeed, Poes swing decreased from 31 ± 15 cmH₂O during spontaneous breathing to 21 ± 10 cmH₂O during CPAP (P < 0.05). The mean physiological CPAP level was 2 ± 2 cmH2₂O higher than the mean clinical CPAP level and was associated with a significantly greater improvement in all indices of respiratory effort (Poes swing 11 ± 5 cm H₂O; P < 0.05 compared to clinical CPAP). Expiratory abdominal activity was present during the clinical CPAP and decreased during physiological CPAP.

CONCLUSIONS

A physiological setting of noninvasive CPAP, based on the recording of Poes and Pgas, is superior to a clinical setting, based on clinical noninvasive parameters. Expiratory abdominal activity was present during spontaneous breathing and decreased in the physiological CPAP setting.

Oxygen therapy for cystic fibrosis

BACKGROUND

The most serious complications of cystic fibrosis (CF) relate to respiratory insufficiency. Oxygen supplementation therapy has long been a standard of care for individuals with chronic lung diseases associated with hypoxemia. Physicians commonly prescribe oxygen therapy for people with CF when hypoxemia occurs. However, it is unclear if empiric evidence is available to provide indications for this therapy with its financial costs and often profound impact on lifestyle.

OBJECTIVES

To assess whether oxygen therapy improves the longevity or quality of life of individuals with CF.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Latest search of Group's Trials Register: 15 May 2013.

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials comparing oxygen, administered at any concentration, by any route, in people with documented CF for any time period.

DATA COLLECTION AND ANALYSIS

Authors independently assessed the risk of bias for included studies and extracted data.

MAIN RESULTS

This review includes 11 published studies (172 participants); only one examined long-term oxygen therapy (28 participants). There was no statistically significant improvement in survival, lung, or cardiac health. There was an improvement in regular attendance at school or work in those receiving oxygen therapy at 6 and 12 months. Four studies examined the effect of oxygen supplementation during sleep by polysomnography. Although oxygenation improved, mild hypercapnia was noted. Participants fell asleep quicker and spent a reduced percentage of total sleep time in rapid eye movement sleep, but there were no demonstrable improvements in qualitative sleep parameters. Six studies evaluated oxygen supplementation during exercise. Again, oxygenation improved, but mild hypercapnia resulted. Participants receiving oxygen therapy were able to exercise for a significantly longer duration during exercise. Other exercise parameters were not altered by the use of oxygen.

AUTHORS' CONCLUSIONS

There are no published data to guide the prescription of chronic oxygen supplementation to people with advanced lung disease due to CF. Short-term oxygen therapy during sleep and exercise improves oxygenation but is associated with modest and probably clinically inconsequential hypercapnia. There are improvements in exercise duration, time to fall asleep and regular attendance at school or work. There is a need for larger, well-designed clinical trials to assess the benefits of long-term oxygen therapy in people with CF administered continuously or during exercise or sleep or both. However, we do not expect any new research to be undertaken in this area any time soon and do not plan to update this review again until any new evidence does become available.

Non-invasive ventilation for cystic fibrosis

BACKGROUND

Non-invasive ventilation may be a means to temporarily reverse or slow the progression of respiratory failure in cystic fibrosis.

OBJECTIVES

To compare the effect of non-invasive ventilation versus no non-invasive ventilation in people with cystic fibrosis.

SEARCH METHODS

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches, handsearching relevant journals and abstract books of conference proceedings. We searched the reference lists of each trial for additional publications possibly containing other trials.Most recent search: 22 February 2013.

SELECTION CRITERIA

Randomised controlled trials comparing a form of pressure preset or volume preset non-invasive ventilation to no non-invasive ventilation in people with acute or chronic respiratory failure in cystic fibrosis.

DATA COLLECTION AND ANALYSIS

Three reviewers independently assessed trials for inclusion criteria and methodological quality, and extracted data.

MAIN RESULTS

Fifteen trials were identified; seven trials met the inclusion criteria with a total of 106 participants. Six trials evaluated single treatment sessions and one evaluated a six-week intervention.Four trials (79 participants) evaluated non-invasive ventilation for airway clearance compared with an alternative chest physiotherapy method and showed that airway clearance may be easier with non-invasive ventilation and people with cystic fibrosis may prefer it. We were unable to find any evidence that NIV increases sputum expectoration, but it did improve some lung function parameters.Three trials (27 participants) evaluated non-invasive ventilation for overnight ventilatory support, measuring lung function, validated quality of life scores and nocturnal transcutaneous carbon dioxide. Due to the small numbers of participants and statistical issues, there were discrepancies in the results between the RevMan and the original trial analyses. No clear differences were found between non-invasive ventilation compared with oxygen or room air except for exercise performance, which significantly improved with non-invasive ventilation compared to room air over six weeks.

AUTHORS' CONCLUSIONS

Non-invasive ventilation may be a useful adjunct to other airway clearance techniques, particularly in people with cystic fibrosis who have difficulty expectorating sputum. Non-invasive ventilation, used in addition to oxygen, may improve gas exchange during sleep to a greater extent than oxygen therapy alone in moderate to severe disease. These benefits of non-invasive ventilation have largely been demonstrated in single treatment sessions with small numbers of participants. The impact of this therapy on pulmonary exacerbations and disease progression remain unclear. There is a need for long-term randomised controlled trials which are adequately powered to determine the clinical effects of non-invasive ventilation in cystic fibrosis airway clearance and exercise.

Physiologic and clinical benefits of noninvasive ventilation in infants with Pierre Robin sequence

OBJECTIVE

The objective of the study was to determine the clinical and physiologic benefits of noninvasive respiratory support (NRS) (continuous positive airway pressure or noninvasive positive pressure ventilation) for infants with a Pierre Robin sequence (PRS).

METHODS

Breathing patterns, respiratory efforts, and gas exchange were analyzed for 7 infants with a PRS during spontaneous breathing and during NRS. Clinical outcomes with duration of NRS and need for a tracheotomy and/or nutritional support was evaluated.

RESULTS

Compared with spontaneous breathing, breathing patterns, respiratory efforts, and transcutaneous carbon dioxide pressures improved during NRS; the mean respiratory rate decreased from 55 ± 9 to 37 ± 7 breaths per minute (P = .063), the mean inspiratory time/total duty cycle decreased from 59 ± 9% to 40 ± 7% (P = .018), the mean esophageal pressure swing decreased from 29 ± 13 to 9 ± 4 cm H(2)O (P = .017), the diaphragmatic pressure-time product decreased from 844 ± 308 to 245 ± 126 cm H(2)O-second per minute (P = .018), and the mean transcutaneous carbon dioxide pressure during sleep decreased from 57 ± 7 to 31 ± 7 mm Hg (P = .043). All of the patients could be discharged successfully from the hospital with NRS. The mean duration of NRS was 16.7 ± 12.2 months. Six patients could be weaned from nutritional support, and none required a tracheotomy.

CONCLUSIONS

NRS is able to improve breathing patterns and respiratory outcomes for infants with severe upper airway obstruction attributable to a PRS, which supports its use as a first-line treatment.

Noninvasive positive-pressure ventilation avoids recannulation and facilitates early weaning from tracheotomy in children

OBJECTIVE

To show that noninvasive positive-pressure ventilation by means of a nasal mask may avoid recannulation after decannulation and facilitate early decannulation.

DESIGN

Retrospective cohort study.

SETTING

Ear-nose-and-throat and pulmonary department of a pediatric university hospital.

PATIENTS

The data from 15 patients (age = 2-12 yrs) who needed a tracheotomy for upper airway obstruction (n = 13), congenital diaphragmatic hypoplasia (n = 1), or lung disease (n = 1) were analyzed. Four patients received also nocturnal invasive ventilatory support for associated lung disease (n = 3) or congenital diaphragmatic hypoplasia (n = 1). Decannulation was proposed in all patients because endoscopic evaluation showed sufficient upper airway patency and normal nocturnal gas exchange with a small size closed tracheal tube, but obstructive airway symptoms occurred either immediately or with delay after decannulation without noninvasive positive-pressure ventilation.

INTERVENTIONS

In nine patients, noninvasive positive-pressure ventilation was started after recurrence of obstructive symptoms after a delay of 1 to 48 mos after a successful immediate decannulation. Noninvasive positive-pressure ventilation was anticipated in six patients who failed repeated decannulation trials because of poor clinical tolerance of tracheal tube removal or tube closure during sleep.

MEASUREMENTS AND MAIN RESULTS

After noninvasive positive-pressure ventilation acclimatization, decannulation was performed with success in all patients. Noninvasive positive-pressure ventilation was associated with an improvement in nocturnal gas exchange and marked clinical improvement in their obstructive sleep apnea symptoms. None of the 15 patients needed tracheal recannulation. Noninvasive positive-pressure ventilation could be withdrawn in six patients after 2 yrs to 8.5 yrs. The other nine patients still receive noninvasive positive-pressure ventilation after 1 yr to 6 yrs.

CONCLUSIONS

In selected patients with upper airway obstruction or lung disease, noninvasive positive-pressure ventilation may represent a valuable tool to treat the recurrence of obstructive symptoms after decannulation and may facilitate early weaning from tracheotomy in children who failed repeated decannulation trials.

Oxygen therapy for cystic fibrosis

BACKGROUND

The most serious complications of cystic fibrosis (CF) relate to respiratory insufficiency. Oxygen supplementation therapy has been a standard of care for individuals with chronic lung diseases associated with hypoxemia for decades. Physicians commonly prescribe oxygen therapy for people with CF when hypoxemia occurs. However, it is unclear if empiric evidence is available to provide indications for this therapy with its financial costs and often profound impact on lifestyle.

OBJECTIVES

To assess whether oxygen therapy improves the longevity or quality of life of individuals with CF.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings.Most recent search of Group's Trials Register: November 2008.

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials comparing oxygen, administered at any concentration, by any route, in people with documented CF for any time period.

DATA COLLECTION AND ANALYSIS

Authors independently assessed study quality and extracted data.

MAIN RESULTS

Eleven published studies (172 participants) are included in this review, of which only one examined long-term oxygen therapy (28 participants). There was no statistically significant improvement in survival, lung, or cardiac health. There was an improvement in regular attendance at school or work in those receiving oxygen therapy at 6 and 12 months. Four studies examined the effect of oxygen supplementation during sleep by polysomnography. Although oxygenation improved, mild hypercapnia was noted. Participants took less time to fall asleep and spent a reduced percentage of total sleep time in rapid eye movement sleep, but there were no demonstrable improvements in qualitative sleep parameters. Six studies evaluated oxygen supplementation during exercise. Again, oxygenation improved, but mild hypercapnia resulted. Participants receiving oxygen therapy were able to exercise for a significantly longer duration during exercise. Other exercise parameters were not altered by the use of oxygen.

AUTHORS' CONCLUSIONS

There are no published data to guide the prescription of chronic oxygen supplementation to people with advanced lung disease due to CF. Short-term oxygen therapy during sleep and exercise improves oxygenation but is associated with modest and probably clinically inconsequential hypercapnia. There are improvements in exercise duration, time to fall asleep and regular attendance at school or work. There is a need for larger, well-designed clinical trials to assess the benefits of long-term oxygen therapy in people with CF administered continuously or during exercise or sleep or both.

Non-invasive ventilation for cystic fibrosis

BACKGROUND

Non-invasive ventilation (NIV) may be a means to temporarily reverse or slow the progression of respiratory failure in cystic fibrosis (CF).

OBJECTIVES

To compare the effect of NIV versus no NIV in people with CF.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches, handsearching relevant journals and abstract books of conference proceedings. We searched the reference lists of each trial for additional publications possibly containing other trials.Most recent search: June 2008.

SELECTION CRITERIA

Randomised controlled trials comparing a form of pressure preset or volume preset NIV to no NIV in people with acute or chronic respiratory failure in CF.

DATA COLLECTION AND ANALYSIS

Three reviewers independently assessed trials for inclusion criteria and methodological quality, and extracted data.

MAIN RESULTS

Fifteen trials were identified; seven trials met the inclusion criteria with a total of 106 participants. Six trials evaluated single treatment sessions and one evaluated a six-week intervention.Four trials (79 participants) evaluated NIV for airway clearance compared with an alternative chest physiotherapy method and showed that airway clearance may be easier with NIV and people with CF may prefer it. We were unable to find any evidence that NIV increases sputum expectoration, but it did improve some lung function parameters.Three trials (27 participants) evaluated NIV for overnight ventilatory support, measuring lung function, validated quality of life scores and nocturnal transcutaneous carbon dioxide. Due to the small numbers of participants and statistical issues, there were discrepancies in the results between the RevMan and the original trial analyses. No clear differences were found between NIV compared with oxygen or room air except for exercise performance, which significantly improved with NIV compared to room air over six weeks.

AUTHORS' CONCLUSIONS

Non-invasive ventilation may be a useful adjunct to other airway clearance techniques, particularly in people with CF who have difficulty expectorating sputum. Non-invasive ventilation, used in addition to oxygen, may improve gas exchange during sleep to a greater extent than oxygen therapy alone in moderate to severe disease. These benefits of NIV have largely been demonstrated in single treatment sessions with small numbers of participants. The impact of this therapy on pulmonary exacerbations and disease progression remain unclear. There is a need for long-term randomised controlled trials which are adequately powered to determine the clinical effects of non-invasive ventilation in CF airway clearance and exercise.

Recurrence plots for dynamical analysis of non-invasive mechanical ventilation

Quantifiers were introduced to convert recurrence plots into a statistical analysis of dynamical properties. It is shown that the Shannon entropy, if properly computed, increases as the chaotic regime is developed as expected. Recurrence plots and a new estimator for the Shannon entropy are then used to identify asynchronisms in non-invasive mechanical ventilation. It is thus shown that the phase coherence-easily identified using a Shannon entropy-is relevant in the quality of the mechanical ventilation. In particular, some patients with chronic respiratory diseases or healthy subjects can have a high rate of asynchronisms but a regular breathing rhythm.

Physiologic benefits of mechanical insufflation-exsufflation in children with neuromuscular diseases

STUDY OBJECTIVES

To analyze the physiologic effects and tolerance of mechanical insufflation-exsufflation (MI-E) by means of mechanical cough assistance (Cough Assist; JH Emerson Company; Cambridge, MA) for children with neuromuscular disease.

DESIGN

Prospective clinical trial.

SETTING

Physiology laboratory of a pediatric pulmonary department of a university hospital.

PATIENTS

Seventeen children with Duchenne muscular dystrophy (n = 4), spinal muscular atrophy (n = 4), or other congenital myopathy (n = 9) who were in a stable state.

INTERVENTIONS

Pressures of 15, 30, and 40 cm H(2)O were cycled to each patient, with 2 s for insufflation and 3 s for exsufflation. One application consisted of six cycles at each pressure for a total of three applications.

MEASUREMENTS AND RESULTS

Airway pressure and airflow were measured during every application. Breathing pattern, vital capacity (VC), sniff nasal inspiratory pressure (SNIP), peak expiratory flow (PEF), and respiratory comfort were evaluated at baseline and after each application. The tolerance of the patients was excellent, with a significant increase in the respiratory comfort score in all of the patients (p = 0.02). Expired volume during the MI-E application increased significantly to reach twice the VC at 40 cm H(2)O. Mean and maximal inspiratory and expiratory flows increased in a pressure-dependent manner. Breathing pattern did not change after the MI-E applications and pulse oximetric saturation remained stable within normal values, but the mean end-tidal carbon dioxide pressure decreased significantly. VC did not change, but the mean SNIP and PEF improved significantly after MI-E applications.

CONCLUSIONS

Our results confirm the good tolerance and physiologic short-term benefit of the MI-E in children with neuromuscular disease who were in a stable state.

Non-invasive ventilation for cystic fibrosis

BACKGROUND

Non-invasive ventilation (NIV) may be a means to temporarily reverse or slow the progression of respiratory failure in cystic fibrosis (CF).

OBJECTIVES

To compare the effect of NIV versus no NIV in people with CF.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register comprising references identified from comprehensive electronic database searches, handsearching relevant journals and abstract books of conference proceedings. We searched the reference lists of each trial for additional publications possibly containing other trials. Most recent search: October 2006.

SELECTION CRITERIA

Randomised controlled trials comparing a form of pressure preset or volume preset NIV to no NIV in people with acute or chronic respiratory failure in CF.

DATA COLLECTION AND ANALYSIS

Three reviewers independently assessed trials for inclusion criteria and methodological quality, and extracted data.

MAIN RESULTS

Fifteen trials were identified; seven trials met the inclusion criteria with a total of 106 participants. Six trials evaluated single treatment sessions only and one evaluated a six-week intervention. Four trials (79 participants) evaluated NIV for airway clearance compared with an alternative chest physiotherapy method and showed that airway clearance may be easier with NIV and people with CF may prefer it. We were unable to find any evidence that NIV increases sputum expectoration, but it did improve some lung function parameters.Three trials (27 participants) evaluated NIV for overnight ventilatory support. Lung function and nocturnal transcutaneous carbon dioxide were evaluated within two trials. Due to the small numbers of participants and statistical issues, there were discrepancies in the results between the RevMan and the original trial analyses. No clear differences were found between NIV compared with oxygen or room air except for exercise performance, which significantly improved with NIV compared to room air over six weeks.

AUTHORS' CONCLUSIONS

Non-invasive ventilation may be a useful adjunct to other airway clearance techniques, particularly in people with CF who have difficulty expectorating sputum. Non-invasive ventilation, when used in addition to oxygen, may improve gas exchange during sleep to a greater extent than oxygen therapy alone in moderate to severe disease. These benefits of NIV have largely been demonstrated in single treatment sessions with small numbers of participants. The impact of this therapy on pulmonary exacerbations and disease progression remain unclear. There is a need for long-term randomised controlled trials which are adequately powered to determine the clinical effects of non-invasive ventilation in CF airway clearance and exercise.

Asynchrony and cyclic variability in pressure support noninvasive ventilation

Noninvasive mechanical ventilation is an effective procedure to manage patients with acute or chronic respiratory failure. Most ventilators act as flow generators that assist spontaneous respiratory cycles by delivering inspiratory and expiratory pressures. This allows the patient to improve alveolar ventilation and subsequent pulmonary gas exchanges. The interaction between the patient and his ventilator are therefore crucial for tolerance and acceptability and part of this interaction is the facility to trigger the ventilator at the beginning of the inspiration. This is directly related to patients' discomfort which is not quantified today. Phase portraits reconstructed from the airflow and first-return maps built on the total breath duration were used to investigate the quality of the patient-ventilator interaction. Phase synchronization can be identified from phase portrait and the breath-to-breath variability is well characterized by return maps. This paper is a first step in the direction of automatically estimating the comfort from measurements and not from a necessarily subjective answer given by the patient. These tools could be helpful for the physicians to set the ventilator parameters.

Noninvasive positive pressure ventilation: five years of experience in a pediatric intensive care unit

OBJECTIVES

To evaluate the feasibility and outcome of noninvasive positive pressure ventilation (NPPV) in daily clinical practice.

DESIGN

Observational retrospective cohort study.

SETTING

Pediatric intensive care unit in a university hospital.

PATIENTS

: Patients treated by NPPV, regardless of the indication, during five consecutive years (2000-2004).

MEASUREMENTS AND RESULTS

A total of 114 patients were included, and 83 of the 114 patients (77%) were successfully treated by NPPV without intubation (NPPV success group). The success rate of NPPV was significantly lower (22%) in the patients with acute respiratory distress syndrome (p < .05) than in the other patients. The Pediatric Risk of Mortality II (p = .003) and Pediatric Logistic Organ Dysfunction scores (p = .002) at admission were significantly higher in patients who were unsuccessfully treated with NPPV (NPPV failure group). Baseline values of Pco2, pulse oximetry, and respiratory rate did not differ between the two groups. A significant decrease in Pco2 and respiratory rate within the first 2 hrs of NPPV was observed in the NPPV success group. Multivariate analysis showed that a diagnosis of acute respiratory distress syndrome (odds ratio, 76.8; 95% confidence interval, 4.4-1342; p = .003) and a high Pediatric Logistic Organ Dysfunction score (odds ratio, 1.09; 95% confidence interval, 1.01-1.17; p = .01) were independent predictive factors for NPPV failure. A total of 11 patients (9.6%), all belonging to the NPPV failure group, died during the study.

CONCLUSIONS

This study demonstrates the feasibility and efficacy of NPPV in the daily practice of a pediatric intensive care unit. This ventilatory support could be proposed as a first-line treatment in children with acute respiratory distress, except in those with a diagnosis of acute respiratory distress syndrome.

Respiratory muscle testing: a valuable tool for children with neuromuscular disorders

RATIONALE

Data on respiratory muscle performance in children with neuromuscular disorders are limited.

OBJECTIVES

The aim of this study was to assess respiratory muscle strength by volitional and nonvolitional tests and to compare these tests with forced vital capacity.

METHODS

Inspiratory muscle strength was assessed by measuring transdiaphragmatic and esophageal pressures generated during volitional and nonvolitional maneuvers, whereas expiratory muscle strength was assessed by measuring the gastric pressure generated during a cough maneuver. Lung volumes were assessed by measuring forced vital capacity.

MEASUREMENTS AND MAIN RESULTS

Forty-one patients with Duchenne muscular dystrophy (n = 20), spinal amyotrophy (n = 8), and congenital myopathy (n = 13) were included, aged 2 to 18 yr. All the patients were able to perform the sniff and the cough maneuver. Sniff transdiaphragmatic pressure decreased with age in Duchenne patients, whereas it increased with age in patients with spinal amyotrophy and congenital myopathy. Magnetic stimulation of the phrenic nerves was obtained in all patients. Twenty-five (61%) patients were able to perform forced vital capacity. In the three groups of patients, a positive correlation was observed between volitional, assessed by the sniff maneuver, and nonvolitional respiratory muscle tests, assessed by the magnetic stimulation of the phrenic nerves. Also, forced vital capacity correlated with sniff transdiaphragmatic pressure and cough gastric pressure.

CONCLUSIONS

Volitional respiratory muscle tests correlated with nonvolitional tests and with forced vital capacity. Simple volitional respiratory muscle tests constitute a valuable tool for the assessment of respiratory muscle strength in young patients with neuromuscular disorders.

Oxygen therapy for cystic fibrosis

BACKGROUND

The most serious complications of cystic fibrosis (CF) relate to respiratory insufficiency. Oxygen supplementation therapy has been a standard of care for individuals with chronic lung diseases associated with hypoxemia for decades. It is common for physicians to prescribe oxygen therapy for people with CF when hypoxemia occurs. However, it is unclear if empiric evidence is available to provide indications for this therapy with its financial costs and often profound impact on lifestyle.

OBJECTIVES

To assess whether oxygen therapy improves the longevity or quality of life of individuals with CF.

SEARCH STRATEGY

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group Trials Register, comprising references identified from comprehensive electronic database searches and handsearches of relevant journals and abstract books of conference proceedings. Most recent search of Group's Trials Register: April 2005.

SELECTION CRITERIA

Randomized or quasi-randomized controlled trials comparing oxygen, administered at any concentration, by any route, in people with documented CF for any time period.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed study quality and extracted data.

MAIN RESULTS

Nine published studies (149 participants) are included in this review, of which only one examined long-term oxygen therapy (28 participants). There was no statistically significant improvement in survival, lung, or cardiac health. Four studies examined the effect of oxygen supplementation during sleep by polysomnography. Although oxygenation improved, there were no demonstrable improvements in qualitative sleep parameters and modest hypoventilation was noted. In three studies, oxygen supplementation was evaluated during exercise. Hypoxemia was prevented, but mild hypercapnia resulted. Work performance was not improved, as measured in one study, but was improved in a second study. Furthermore, in two studies, exercise duration was enhanced by oxygen supplementation. In the study examining the impact of oxygen supplementation after exercise, recovery time was enhanced.

AUTHORS' CONCLUSIONS

There are no published data to guide the prescription of chronic oxygen supplementation to people with advanced lung disease due to CF. Short-term oxygen therapy during sleep and exercise improves oxygenation but is associated with modest and probably clinically inconsequential hypercapnia. During exercise, there are improvements in exercise duration and peak performance. There is a need for larger, well-designed clinical trials to assess the benefits of long-term oxygen therapy in people with CF administered continuously or during exercise or sleep or both.

Facial side effects during noninvasive positive pressure ventilation in children

OBJECTIVE

The study quantified the side effects of nasal masks use for noninvasive positive pressure ventilation (NPPV) in children.

DESIGN AND SETTING

Cross-sectional retrospective study in a tertiary pediatric university hospital.

PATIENTS

Patients with obstructive sleep apnea (n=16), neuromuscular disorders (n=14), and cystic fibrosis (n=10).

INTERVENTIONS

Clinical evaluation of facial tolerance.

MEASUREMENTS AND RESULTS

A skin injury was observed in 19 patients (48%), with a transient erythema in 7 (18%), prolonged erythema in 9 (23%), and skin necrosis in 3 (8%). Skin injury was associated with age over 10 years (OR=16) and use of a commercial mask (OR=15) and was less frequent in patients with obstructive sleep apnea. The change of a commercial mask for a custom-made mask was associated with reduction in the skin injury score. Global facial flattening was present in 68% of the patients. No correlation was observed with age, daily or cumulative use of NPPV, or the type of mask. A maxillary retrusion was present in 37% of patients. No correlation was observed with age or the type of mask or the underlying disease, but an association was found with a longer daily use of NPPV (OR=6.3).

CONCLUSIONS

The prevalence of facial side effects is clinically significant in children using NPPV. Systematic maxillofacial follow-up enables these effects to be identified. Remedial measures could include the change of the interface or reducing the daily use of NPPV.

L’assistance ventilatoire non invasive à domicile chez l’enfant

INTRODUCTION

Non-invasive positive pressure ventilation (NPPV) represents a particularly interesting technique of ventilatory support in paediatrics. Indeed, a significant number of pathologies that may be responsible for chronic respiratory insufficiency in childhood, such as neuromuscular diseases, obstruction of the upper airways, disorders of chest wall and/or the lungs, and disorders of ventilatory control may all lead to alveolar hypoventilation that can be improved by ventilatory support.

BACKGROUND

Few physiological studies have been performed on NPPV in children. The most appropriate modes and settings for each pathology have not been clearly defined, and the criteria for commencing NPPV are based essentially on consensus guidelines for the management of neuromuscular disorders.

VIEWPOINT

All the health care professionals managing these children should combine their efforts to evaluate more precisely the medium and long-term physiological effects of NPPV on the respiratory muscles, the development of the respiratory system, inspiratory activity, the indications for starting treatment and, above all, the benefits in terms of psycho-neurological development and quality of life.

CONCLUSIONS

A better evaluation of the medium and long-term physiological and psychological benefits together with technical improvements in ventilators and associated equipment should allow a rapid expansion in the use of domiciliary NPPV in children.

Nutritional status is an important predictor of diaphragm strength in young patients with cystic fibrosis

BACKGROUND

The effect of nutritional status and lung disease progression on diaphragm strength in young patients with cystic fibrosis remains unclear.

OBJECTIVE

The aim of this study was to investigate the effect of nutritional status and airway obstruction on diaphragm strength.

DESIGN

Twitch transdiaphragmatic pressure (Tw Pdi) obtained by bilateral anterior magnetic phrenic nerve stimulation, body mass index (BMI) z score, fat mass, fat-free mass (FFM), arm muscle circumference (AMC), forced expiratory volume in 1 s (FEV(1)), and functional residual capacity (FRC) were measured in 20 patients aged 15.1 +/- 2.8 y (x +/- SD). Values were expressed as a percentage of predicted values.

RESULTS

Mean (+/-SD) Tw Pdi was 24.3 +/- 5.5 cm H(2)O. Univariate regression analysis showed positive correlations between Tw Pdi and nutrition scores (BMI z score: r = 0.63, P = 0.003; FFM: r = 0.47, P = 0.04; AMC: r = 0.45, P = 0.04), airway obstruction (FEV(1): r = 0.68, P = 0.001), and arterial oxygen partial pressure (r = 0.68, P = 0.001). Negative correlations were observed between Tw Pdi and dynamic hyperinflation (FRC: r = -0.65, P = 0.005) and arterial carbon dioxide pressure (r = -0.50, P = 0.03). Furthermore, stepwise regression analysis showed that Tw Pdi correlated with BMI z score (r = 0.75, P = 0.0002) and FEV(1) (r = 0.69, P = 0.001).

CONCLUSIONS

Diaphragm strength is relatively well preserved in young patients with cystic fibrosis. However, the strength of the diaphragm decreases with the progression of malnutrition and airway obstruction.

The effect of back-up rate during non-invasive ventilation in young patients with cystic fibrosis

OBJECTIVE

The aim of the study was to evaluate the effect of the back-up rate on respiratory effort during non-invasive mechanical ventilation.

DESIGN

An in vitro study evaluated the inspiratory trigger in seven domiciliary ventilators. Then, a prospective, randomized, crossover trial compared the effect on respiratory effort of three different back-up rates during pressure support (PS) and assist-control/volume-targeted (AC/VT) ventilation.

SETTING

A research unit and a tertiary referral pediatric center.

PATIENTS

Ten patients with cystic fibrosis (CF).

INTERVENTIONS

During the in vivo study, the back-up rate was progressively increased to the maximum that patients could tolerate (Fmax) and respiratory effort, as judged by pressure/time product of the diaphragm (PTPdi/min), was compared between the two ventilatory modes.

RESULTS

Differences were observed between trigger pressure, trigger time delay, trigger pressure/time product and the slope between flow and pressure in the seven ventilators. PS and AC/VT ventilation were associated with a decrease in respiratory effort (PTPdi/min was 518+/-172, 271+/-119 and 291+/-138 cmH(2)O. s(-1). min(-1), for spontaneous breathing, PS and AC/VT ventilation, respectively, p=0.05). During the two modes, increasing the back-up rate to Fmax resulted in a greater reduction in PTPdi/min (p=0.001), which was more pronounced during AC/VT ventilation, due to the automatic adjustment of the inspiratory/expiratory time ratio.

CONCLUSIONS

Increasing the back-up rate during PS and AC/VT ventilation decreases respiratory effort in young patients with CF, but this effect was more marked with AC/VT ventilation.

Measurement of diaphragm loading during pressure support ventilation

OBJECTIVE

The diaphragmatic pressure-time product (PTPdi) has been used to quantify the loading and unloading of the diaphragm. The validity of the relationship between PTPdi and diaphragm electrical activity (EMGdi) during pressure-support ventilation (PSV) is unclear. We examined this relationship.

DESIGN AND SETTING

Physiological study in a physiology laboratory.

SUBJECTS

Six healthy adults.

INTERVENTIONS

Spontaneous breathing (SB) and two levels of PSV (6 and 12 cmH(2)O), breathing room air and incremental concentrations of carbon dioxide, sufficient to achieve an EMGdi signal of approximately 200% of baseline value.

MEASUREMENTS AND RESULTS

We measured the electrical (EMGdi) and mechanical (PTPdi) activity of the diaphragm using oesophageal electrode and oesophageal and gastric balloon catheters. The relationship between EMGdi and PTPdi during SB was linear in five subjects and curvilinear in one. However, with PSV 12 cmH(2)O we observed that the relationship between EMGdi and PTPdi was 'left shifted'; specifically, for any given level of EMGdi the PTPdi was smaller with PSV 12 cmH(2)O than during SB. However, when PTPdi was converted to power (the product of pressure and flow) the tendency to left shift was largely reversed.

CONCLUSIONS

We conclude that when assessing of diaphragm unloading during PSV flow measurements are required. Where flow is constant, PTPdi is a valid measure of diaphragm unloading, but if not these data may be used to make an appropriate correction.

Long-term noninvasive mechanical ventilation for children at home: a national survey

Experience with domiciliary noninvasive mechanical ventilation (NIMV) in children is limited. The aim of this study was to determine the number of patients and categorize the use of domiciliary NIMV in children in France. An anonymous cross-sectional national study was performed, using a postal questionnaire sent to all specialist centers utilizing domiciliary NIMV for chronic respiratory failure. Patients aged <18 years and receiving home NIMV were included in the study. Detailed information was obtained from 102 patients from 15 centers: 4/15 centers cared for 84% of patients; 7% of patients were under 3 years old; 35% were between 4-11 years old; and 58% were older than 12 years. Underlying diagnoses included neuromuscular disease (34%), obstructive sleep apnea (OSA) and/or cranio-facial abnormalities (30%), cystic fibrosis (17%), congenital hypoventilation (9%), scoliosis (8%), and other disorders (2%). NIMV was started because of nocturnal hypoventilation (67%), acute exacerbation (28%), and/or failure to thrive (21%). Volume-targeted ventilation was preferred in restrictive disorders (56%) and central hypoventilation (56%), while pressure support ventilation (PSV) was preferred in cystic fibrosis (71%). Patients with OSA and/or cranio-facial abnormalities were ventilated with continuous positive airway pressure (45%) or bilevel PSV (52%). In conclusion, NIMV is currently used in France for the domiciliary management of children with a variety of conditions causing chronic respiratory failure. However, NIMV in children is still performed on a small scale, and combined with the heterogeneity of the patient population, its application would best be served by centers specializing in the initiation and long-term follow-up of these patients.

Comparison of proportional assist ventilation and pressure support ventilation in chronic respiratory failure due to neuromuscular and chest wall deformity

BACKGROUND

The physiological and symptomatic effects of proportional assist ventilation (PAV) and pressure support ventilation (PSV) were compared in stable awake patients with neuromuscular and chest wall deformity (NMCWD).

METHODS

Oxygen saturation (SaO(2)), transcutaneous carbon dioxide (TcCO(2)), minute ventilation (VE), tidal volume (VT), respiratory rate (RR), and diaphragm electromyography (EMGdi) were measured in 15 patients during both modes. Subjective effort of breathing and synchrony with the ventilator were assessed using visual analogue scales.

RESULTS

Three of 15 patients failed to trigger the ventilator in either mode and were excluded. In the 12 remaining patients there were similar improvements in SaO(2), TcCO(2), VE, VT, and RR during both modes. The mean (SD) percentage fall in EMGdi was greater during PSV (-80.5 (10.7)%) than during PAV (-41.3 (35.2)%; p= 0.01). Effort of breathing (p=0.004) and synchrony with the ventilator (p=0.004) were enhanced more with PSV than with PAV.

CONCLUSION

Both PSV and PAV produced similar improvements in physiological parameters. However, greater diaphragm unloading was observed with PSV than with PAV, associated with greater symptomatic benefit. These findings suggest that tolerance to PAV may be compromised in patients with NMCWD.

Changes in pulmonary mechanics with increasing disease severity in children and young adults with cystic fibrosis

As forced expiratory volume in 1 second (FEV(1)) is a major predictor of outcome in patients with cystic fibrosis (CF), we investigated the effect of FEV(1) on pulmonary mechanics in children and young adults with CF. We measured respiratory rate; tidal volume; minute ventilation; arterial blood gases; sniff esophageal pressure; dynamic lung compliance; total pulmonary resistance; intrinsic positive end expiratory pressure; and total, elastic, and resistive work of breathing in 32 patients (FEV(1) range: 12-49% predicted). We observed correlations between FEV(1) and Pa(O(2)) (r = 0.76, p < 0.0001) and Pa(CO(2)) (r = -0.70, p < 0.0001), FEV(1) and respiratory rate/tidal volume (r = -0.41, p = 0.02), FEV(1) and dynamic lung compliance (r = 0.64, p < 0.0001), and FEV(1) and total work of breathing (r = -0.52, p = 0.002) and elastic work of breathing (r = -0.60. p = 0.0003). No correlations were observed between FEV(1) and sniff esophageal pressure (p = 0.5), minute ventilation (p = 0.9), total pulmonary resistance (p = 0.3), intrinsic positive end expiratory pressure (p = 0.3), or resistive work of breathing (p = 0.1). As FEV(1) declines in children and young adults with CF, there is an increase in the elastic load and work of breathing, resulting in a rapid shallow breathing pattern, that is associated with further impairment of gas exchange.