Noninvasive Ventilatory Support

Indications for Noninvasive Ventilatory Support A. Disease Categories 

A large number of conditions can result in chronic ventilatory failure and patients with these conditions may benefit from home ventilation. Typically, patients with restrictive disorders have decreased compliance of the chest wall, resulting from a thoracic cage deformity or from respiratory muscle involvement (1). In patients with severe obstructive pulmonary disorders, respiratory muscle fatigue and alveolar hypoventilation, especially during sleep, are thought to contribute to respiratory failure (2,3) (Table 1). 

It is useful to define the disease category in order to predict the natural history and specific intervention. It is well known that patients with primarily restrictive disorders can have both inspiratory and expiratory muscle weakness, and apart from noninvasive ventilation (NIV), they also need cough assistance (4,5). On the other hand, patients with obstructive disorders rarely need mechanical expiratory aids except when they have a severe infectious exacerbation at which time difficulties in clearing copious secretions can occur (4,6,7). 

Some neuromuscular diseases, for example Guillain-Barre syndrome, may only require temporary ventilatory support (8) while others, such as post-polio syndrome require lifelong noninvasive ventilatory support (9). Amyotrophic lateral sclerosis (ALS) is a 

Restrictive disorders Chest wall disorders Kyphoscoliosis Thoracoplasty Fibrothorax 

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Ellis E, Grunstein R, Chan S, et al. Noninvasive ventilatory support durino sleep improves respiratory failure in kyphoscoliosis. Chest 1988 94 811-815. 

Van t Hul A, Kwakkel G, Gosselink R. The acute effects of noninvasive ventilatory support during exercise on exercise endiurance and dyspnea in patients with chronic obstructive pulmonary disease a systematic review. J Cardiopulm Rehabil 2002 22 290-297. 

In this chapter we will discuss recommendations from the hterature regarding dec-aruiulation as well as our personal clinical experience. We will comment on the pathophysiology of ventilator dependence, the determination of candidates for weaning from ventilation and tracheostomy, and a stepwise approach to decannulation. Lastly, we will discuss the choices of noninvasive ventilatory supports and techniques that clinicians may utilize, such as lung volume recruitment (LVR), assisted coughing and mechanical airway clearance. 

Bach JR. A historical perspective on the use of noninvasive ventilatory support alternatives. Respir Care Clin N Am 1996 2(2) 161-181. 

Bach JR, Alba AS. Intermittent abdominal pressure ventilator in a regimen of noninvasive ventilatory support. Chest 1991 99 630-636. 

Noninvasive positive-pressure ventilation (NPPV) provides ventilatory support with oxygen and pressurized airflow using a face or nasal mask with a tight seal but without endotracheal intubation. In patients with acute respiratory failure due to COPD exacerbations, NPPV was associated with lower mortality, lower intubation rates, shorter hospital stays, and greater improvements in serum pH in 1 hour compared with usual care. Use of NPPV reduces the complications that often arise with invasive mechanical ventilation. NPPV is not appropriate for patients with altered mental status, severe acidosis, respiratory arrest, or cardiovascular instability. 

Bach JR, Alba A. Noninvasive options for ventilatory support of the traumatic high level... 

Figure 2 A 37-year-old with Duchenne muscular dystrophy, vital capacity 270 mL, continuously dependent on noninvasive ventilation seen here using lipseal ventilation for nocturnal ventilatory support.

Chronic ventilatory support is currently a well-accepted therapy in patients with chronic respiratory failure due to thoracic cage abnormalities or in patients with neuromuscular disease. In contrast, the evidence to use chronic ventilatory support in patients with obstructive lung disease is less clear. Most of studies in this area have been in patients with chronic obstructive pulmonary disease (COPD) and only a few in patients wiA cystic fibrosis (CF) and bronchiectasis. In this chapter, we will focus primarily on COPD, discussing first the rationale of noninvasive positive pressure ventilation (NIPPV) in these patients and second all randomized controlled studies. Thereafter, we will elaborate on different issues that might be important in making NIPPV more effective in patients with COPD. Finally, we will discuss the effeets of ehronie ventilatory support in patients with CF and bronchiectasis. 

The effective elimination of airway mucus and other debris is one of the most important factor that permits successful use of chronic and acute ventilation support (noninvasive and invasive) for patients with either ventilatory or oxygenation impairment. In ventilatory dependent patients, the goals of intervention are to maintain lung compliance and normal alveolar ventilation at all times and to maximize cough flows for adequate bronchopulmonary secretion clearance (6). 

During the 1970s, more patients with respiratory failure due to neuromuscular disorders and chest wall deformities received long-term ventilatory assistance at home, either via tracheostomy or body ventilators, which provided effective nocturnal noninvasive ventilation (NIV) (5,6). In the 1970s, the development of home respiratory therapy companies improved support for home mechanical ventilation (HMV). Respiratory therapists could now set up ventilatory equipment, educate the patient and caregivers about using the equipment, and be available to deal with problems. 

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