Enough is Enough! The efficacy of intermittent noninvasive ventilation in stabilizing respiratory failure and symptoms of hypoventilation in patients with slowly progressive neuromuscular diseases was first reported well through a decade ago.

Enough is Enough!

The efficacy of intermittent noninvasive ventilation in stabilizing respiratory failure and symptoms of hypoventilation in patients with slowly progressive neuromuscular diseases was first reported well through a decade ago.[1,2] The earlier studies used mainly negative influence ventilators, but because of greater convenience, portability, and avoidance of the slumber apnea induced in many patients by the agency of negative pressure ventilation,[3] nonivasive positive compressing ventilation (NPPV) has become the prevailing style of first choice in late years. Within the past 6 years, numerous studies using NPPV have confirmed the earlier findings that intermittent noninvasive ventilation, mainly nocturnal, is associated with reversal of hypercapnia and symptoms in patients with chronic respiratory failure becoming to many neuromuscular diseases.[4-9]

Despite the unaminously favorable be the effects of the prior studies, no controll prospective trials have been done to confirm the efficacy of NPPV as it was studies were not done mainly because witholding from sway subjects what was almost certainly effective treatment to assay survival benefit would have been ethically unjustifiable. In the quick in emergencies issue of Chest (see page 445) Vianello and colleagues have avoided this ethical question at issue by comparing the clinical course of five patients with Duchenne muscular dystrophy (DMD) who accepted nasal NPPV with that of five patients who refused. Although the number of patients listed was small, the results present the appearance unequivocal after two years of follow-up all nasally ventilated patients were alive, whereas four of the five "control subjects" had died.

Should we now accept that nasal NPPV is highly effective at improving survival in this patient population? The doubters will point public that in addition to the small number of patients in this trial, it was not randomized, and although the baseline differences between the form into groupss were not statistically significant, there was a incline toward greater age, lower VT and higher [PaCO.sub.2] in the "control" form into groups perhaps predisposing to the higher mortality. Despite these limitations, however, the evidence in the current study combined with that of the numerous previous studies gives virtually unequivocal the conclusion that NPPV is highly efficacious in improving gas exchange abnormalities, symptoms, and survival in patients with DMD and with other slowly progressive neuromuscular diseases as well.

Despite the convincing nature of the survival data, the contention that NPPV stabilizes respiratory muscle function in patients with DMD must be scrutinized. The inquiry followed patients for only 2 years, and a initial improvement in pulmonary function might have been anticipated if NPPV alleviated hypoxemia or hypercapnia.[10] so an improvement could have masked the los of pulmonary function related to the inexorable progression of the underlying disease. Whether or not NPPV alters this progression in any way other than at stabilizing gas exchange is unclear, if it were not that previous studies demonstrate that uniform with effective noninvasive ventilation, pulmonary function eventually deteriorates, with the patient using the ventilator for more and more time each day.[11] Tracheostomy might eventually be advised, although certain investigators have reported succes in managing patients with NPPV who have virtually no capacity for spontaneous breathing.[12]

At the instant time, NPPV, initially nocturnal, should be considered the treatment of first choice for symptomatic patients with chronic respiratory failure suitable to slowly progressive neuromuscular diseases in the same state [i]or[/i] condition as DMD, other muscular dystrophies, postpolio syndrome or occasional patients with multiple sclerosis or amyotrophic lateral sclerosis who have intact upper airway function. Exceptions might include those meditation to have a major component part of central hypoventilation who could experience progesterone initially, and those with significant obstructive doze apnea who could try nasal CPAP,[13] if it be not that patients not responding successfully should receive NPPV Other noninvasive ventilators should now be considered next to the first choices, to be offered to patients who fail to tolerate NPPV The evidence to support this approach has become likewise strong that the focus of investigation should now shift from questions of NPPV efficacy to questions of to what extent it works, and how its implementation can be optimized.

REFERENCES

[1] Curran FJ Night ventilation by way of body respirators for patients in chronic respiratory failure suitable to late stage Duchenne muscular dystrophy Arch Phy M Rehabil 1981 62:270-74

[2] Garay SM Turino GM Goldring RM Sustained reversal of chronic hypercapnia in patients with alveolar hypoventilation syndromes: long-term maintenance with noninvasive mechanical ventilation. Am J M 1981 70:269-74

[3] Hill N Redline s Carskadon M, Curran FJ, Millman RP Sleep-disordered breathing in patients with Duchenne muscular dystrophy using negative constraining force ventilators. Chest 1992 102:1656-62

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