Neuromuscular ventilatory insufficiency: effect of home mechanical ventilator use v oxygen therapy on pneumonia and hospitalization rates

Maximum insufflation capacity: vital capacity and cough flows in neuromuscular disease

OBJECTIVE

To investigate the relationships between vital capacity (VC), maximum insufflation capacity (MIC), and both unassisted and assisted peak cough flows (PCFs).

DESIGN

The 108 patients were divided into two groups, those whose MICs were greater than their VCs (group 1) and those whose MICs could not exceed their VCs (MIC = VC, or group 2).

RESULTS

The MIC correlated positively with the VC for group 1 patients, but the percent increase in MIC correlated negatively with VC. Both VC and MIC correlated significantly with both unassisted and assisted PCF, respectively. Assisting the cough increased the PCF of 37 patients over a previously defined critical level of 2.7 L/sec. The MIC VC difference and percent increase in MIC also correlated significantly with the difference between unassisted and assisted PCF. Although the group 2 patients did not have true cough flows because of inability to close the glottis, their peak expiratory flows were significantly less than the unassisted and assisted PCF of the group 1 patients.

CONCLUSIONS

The greater the MIC VC difference, the greater the PCF, and, thereby, the ability to expel airway mucus and avert respiratory complications. The lower the VC, the greater the percent increase in MIC and the greater the percent increase in assisted PCF. Maximal insufflations are extremely important to increase PCF for patients with neuromuscular conditions who have VCs of < 1500 ml.

Spinal muscular atrophy type 1: A noninvasive respiratory management approach

STUDY OBJECTIVE

To determine whether spinal muscular atrophy (SMA) type 1 can be managed without tracheostomy and to compare extubation outcomes using a respiratory muscle aid protocol vs conventional management.

DESIGN

A retrospective cohort study.

METHODS

Eleven SMA type 1 children were studied during episodes of respiratory failure. Nine children required multiple intubations. Along with standard treatments, these children received manually and mechanically assisted coughing to reverse airway mucus-associated decreases in oxyhemoglobin saturation. Extubation was not attempted until, most importantly, there was no oxygen requirement to maintain oxyhemoglobin saturation greater than 94%. After extubation, all patients received nasal ventilation with positive end-expiratory pressure. Successful extubation was defined by no need to reintubate during the current hospitalization.

RESULTS

Two children have survived for 37 and 66 months and have never been intubated despite requiring 24-h nasal ventilation since 5 and 7 months of age, respectively. One other child underwent tracheostomy for persistent left lung collapse and inadequate home care, another for need for frequent readmission and intubation, and one child was lost to follow-up 3 months after successful extubation. The other six children have been managed at home for 15 to 59 (mean 30.4) months using nocturnal nasal ventilation after an episode of respiratory failure. The nine children were successfully extubated by our protocol 23 of 28 times. The same children managed conventionally were successfully extubated 2 of 20 times when not using this protocol (p < 0.001 by the two-tailed Fisher's Exact t Test).

CONCLUSION

Although intercurrent chest colds may necessitate periods of hospitalization and intubation, tracheostomy can be avoided throughout early childhood for some children with SMA type 1.

Kyphoscoliosis ventilatory insufficiency: noninvasive management outcomes

OBJECTIVE

To determine the effects on symptoms, pulmonary function, sleep, and other clinical variables of treating kyphoscoliosis-associated chronic alveolar hypoventilation with nocturnal nasal ventilation.

DESIGN

Sixteen patients with kyphoscoliosis were treated with nocturnal nasal ventilation delivered by volume-cycled (seven patients) and pressure-cycled (nine patients) ventilators. Dyspnea, morning headaches, fatigue, hypersomnolence, and perceived sleep quality were assessed.

RESULTS

All pretreatment symptoms improved significantly with nasal ventilation. Likewise, PaO2 (mm Hg), PaO2/FlO2, PaCO2 (mm Hg), pH, and forced vital capacity (in milliliters and as a percentage of predicted normal) significantly improved with treatment. Maximum inspiratory pressures and maximum expiratory pressures also significantly increased. Tidal volumes increased significantly and breathing frequency decreased (not significant). Although perceived sleep quality improved, as well as sleep oxyhemoglobin saturation, there was no significant change in sleep architecture. Hospitalization days for respiratory difficulties also decreased from 10.9 +/- 13.3 days in the 6 mo before intermittent positive-pressure ventilation to 0 days during the first 6 mo of treatment.

CONCLUSIONS

Although not apparently affecting sleep architecture, nocturnal nasal ventilation can significantly improve nocturnal and daytime blood gases, pulmonary function, and symptoms of hypoventilation for patients with severe kyphoscoliosis.

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.

Pulmonary evaluation and prevalence of non-invasive ventilation in patients with amyotrophic lateral sclerosis: a multicenter survey and proposal of a pulmonary protocol

In order to evaluate the current standard of care for the management of respiratory failure in patients with amyotrophic lateral sclerosis (ALS), a questionaire was mailed to the Medical Directors of 48 multidisciplinary ALS centers in the United States. Twenty centers reported information on 2357 patients, mean of 124 patients per center. Pulmonary function tests were performed at each visit in 17/20 institutions. Arterial blood gases, maximal expiratory pressures and maximal inspiratory pressures were followed in three centers and serum chloride was monitored in only four centers. The use of non-invasive ventilation (NIV) was extremely variable (range 0-50%) and included 360 patients (15%). The majority of centers used symptoms/signs of hypoventilation and worsening forced vital capacity (FVC) to initiate NIV with no established protocol. A FVC between 20 and 40% was used by most centers to initiate NIV. Due to great variability in the approach to monitoring pulmonary function among ALS centers and the modest effects of current medications to slow disease progression, we propose the use of a structured protocol which can prospectively study the role of NIV in prolonging survival and improving quality of life.

Evaluation and rehabilitation of patients with adult motor neuron disease

Adult motor neuron disease (amyotrophic lateral sclerosis [ALS]) is a neurodegenerative disorder characterized by loss of motor neurons in the cortex, brain stem, and spinal cord, manifested by upper and lower motor neuron signs and symptoms affecting bulbar, limb, and respiratory musculature. Clinically, the disease course is characterized by progressive weakness, atrophy, spasticity, dysarthria, dysphagia, and respiratory compromise, ultimately resulting in death or mechanical ventilation in the vast majority of patients. Patterns of presentation and pathological features of the disease, along with clinical and electrophysiologic criteria for diagnosis, are discussed in this review. Since 8% to 22% of patients survive more than 10 years without ventilator use, meticulous medical and rehabilitation management is extremely important to ensure optimal health and quality of life in these patients. Major issues in the care of individuals with ALS include weakness and spasticity, impairments in activities of daily living and mobility, communication deficits and dysphagia in those with bulbar involvement, respiratory compromise, fatigue and sleep disorders, pain, and psychosocial distress. Research in ALS changes rapidly, but is currently focused on potential etiologic factors such as glutamate excitotoxicity, role of oxidative stress, autoimmunity to calcium channels, and cytoskeletal abnormalities, as well as related treatment initiatives including glutamate modulators, neurotrophic factors, antioxidants, antiapoptotic factors, and gene therapy. Recently, mutations in the gene encoding Cu/Zn superoxide dismutase were identified in a subset of familial ALS patients. Riluzole, a glutamate antagonist and Na-channel blocker, became the only drug currently approved for treatment of ALS after studies showed a small positive effect on survival. Until a definitive treatment or cure for ALS is found, the multifaceted rehabilitation team approach remains the best hope for improving health and survival in this devastating illness.

Noninvasive management of pediatric neuromuscular ventilatory failure

OBJECTIVE

To evaluate the use of mouth piece/nasal intermittent positive-pressure ventilation (IPPV) as an alternative to intubation or to permit extubation for patients with primarily neuromuscular ventilatory impairment and no ventilator-free breathing ability.

DESIGN

A case control study.

INTERVENTIONS

Using a protocol in which oxyhemoglobin desaturation was prevented or reversed by the continuous use of noninvasive IPPV and manually and mechanically assisted coughing as needed, patients with neuromuscular ventilatory failure and no ventilator-free breathing ability were managed noninvasively or extubated to continuous use of noninvasive IPPV for ventilatory support on room air.

MEASUREMENTS AND MAIN RESULTS

Four of ten patients who presented in acute ventilatory failure were managed without intubation, despite becoming dependent on continuous ventilator use. The six intubated patients were extubated successfully to continuous noninvasive IPPV once normal arterial oxygen saturation levels could be maintained on room air, despite their having no ventilator-free breathing ability.

CONCLUSIONS

The use of inspiratory and expiratory aids can decrease the need for intubation for patients with neuromuscular ventilatory failure in the absence of significant lung disease. It can also permit extubation, despite the need for continuous ventilatory support and, thereby, decrease the need to resort to tracheostomy.

Central alveolar hypoventilation in neurosarcoidosis

Although the lung is almost always involved in sarcoidosis and respiratory failure is not uncommonly caused by intrinsic lung disease, chronic alveolar hypoventilation on the basis of neurosarcoidosis has not been previously described. This report describes the case of a 42-year-old woman with sarcoidosis and documented involvement of the lungs, muscle, peripheral nerves, and skin. She presented with ventilatory failure and a vital capacity of 700mL and required hospitalization for intubation and mechanical ventilation. After failing ventilator weaning attempts and requiring continuous ventilatory assistance, she was extubated to continuous use of noninvasive intermittent positive pressure ventilation (IPPV). She eventually weaned to nocturnal-only use of noninvasive IPPV. However, her PaCO2 remained elevated during daytime hours despite the fact that her vital capacity had returned to 3,600mL. She was not obese, and her oxyhemoglobin saturation (SaO2) was normal on room air. Subsequent attempts to discontinue nocturnal nasal IPPV resulted in marked nocturnal decreases in SaO2 and return of symptoms. This case illustrates successful noninvasive management of an apparently unique occurrence of central alveolar hypoventilation caused by neurosarcoidosis.

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.

Kinematic analysis of patients with spinal muscular atrophy during spontaneous breathing and mechanical ventilation

Patients with infantile spinal muscular atrophy develop pectus excavatum along with a severe restrictive syndrome as a result of failure to expand the upper chest wall and lungs because of intercostal muscle weakness. By using an automatic motion analyzer to provide three-dimensional computer analyses of images sampled at 25 Hz, 9 spinal muscular atrophy Type II patients and 13 controls underwent kinematic analysis of thoracoabdominal movements partitioned into the upper thorax, lower thorax, and abdominal volume compartments. The analyses were performed during spontaneous breathing for the controls and during spontaneous breathing and while using mechanically assisted ventilation for the patients. Vital capacity, maximum inspiratory pressures, and nocturnal oxyhemoglobin saturation and transcutaneous carbon dioxide tensions were also measured for the patients. The kinematic data demonstrated a paradoxical ventilatory pattern for the spontaneously breathing SMA patients with the following inspiratory volume changes: upper thorax, -6.4+/-9.6%; lower thorax, 7.3+/-15.8%; abdominal, 99.1+/-21.3%. During mechanical ventilation, the compartmental volume changes were as follows: upper thorax, 13.5+/-6%; lower thorax, 13.7+/-7.9%; abdominal, 72.7+/-9.3%. This kinematic pattern is comparable with that seen in spontaneously breathing normal subjects. We conclude that mechanical ventilation can normalize kinematic volume changes during alveolar ventilation and that this might help deter loss of thoracic compliance caused by the chronic hypoventilation of the upper thoracic compartments. Kinematic analysis may be helpful for choosing the ventilation parameters to optimize therapeutic benefits.