Nasal intermittent positive pressure ventilation is older than you think

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We enjoyed the recent review of noninvasive ventilation (NIV) by Robert and Argaud [1] but wish to point out some historical imprecisions. The authors cited the first use of mouthpiece NIV in a 1998 publication. However, mouthpiece NIV for daytime support was actually first reported by Dr John Affeldt [2] in 1953. The authors noted that use of “mask,” that is, nasal and oronasal interface NIV, in the 1980s first permitted extubation of patients to NIV. Actually, the first interface was used for this purpose with the Bennett lipseal (Nellcor Puritan Bennett Inc, Pleasanton, CA, USA). The lipseal permitted extubation of postpolio and other neuromuscular weakness patients to continuous NIV as early as 1968 [3], [4]. Before this, postsurgical (Harrington rod for scoliosis) patients were extubated back to iron lungs and other body ventilators [4]. More important, in referring to Duchenne muscular dystrophy, the authors state that, “isolated reduced Pao₂ does not require mechanical ventilation but only supplemental oxygen because it does not indicate hypoventilation but only a mismatching of ventilation and perfusion.” However, hypoxia can also be due to hypoventilation as well as airway encomberment, and if the latter is not alleviated, it is often due to lung pathologic condition. The use of supplemental oxygen rather than normalizing ventilation with NIV or clearing secretions (with assisted coughing) can result in CO₂ narcosis. The authors also state that in the presence of daytime hypoventilation the purpose of a sleep study (polysomnogram) “is only to rule out obstructive or central apnea.” However, the polysomnogram is only programmed to interpret paradoxical chest wall motion as an “obstructive apnea” rather than failure of chest wall muscles to contribute to alveolar ventilation. Thus, for patients with paradoxical breathing, the polysomnogram may not be helpful. The authors consider nasal intermittent positive pressure ventilation “survival compared to control treatment.” However, statistical prolongations of survival by nocturnal-only NIV for symptomatic treatment are relatively insignificant compared to true extended survival of patients who have little or no vital capacity and no ventilator-free breathing ability. There, prolongation of survival is indisputable [4]. The authors note that the “main goal of nasal intermittent positive pressure ventilation…is to improve arterial blood gases.” However, another strategy, equally unsubstantiated by clinical research, is to rest inspiratory muscles as much as possible during sleep so that they are better rested for spontaneous breathing. We have managed more than 1000 patients by providing full nocturnal respiratory muscle rest at high-ventilator–delivered volumes (800-1500 mL) and/or pressures of more than 18 cm H₂O. There is no evidence that this is a more effective approach, and it may cause reflex upper airway narrowing during sleep to prevent hyperventilation, but it is simpler because “titrations” of ventilator settings are completely unnecessary and uncomfortable “expiratory positive airway pressure” is avoided. Although aerophagia is associated with high NIV pressures during nocturnal use, there is no reason to assume that it is “more commonly seen when using…mouthpiece ventilation” other than for the obvious fact that 24 hour-ventilator users are more likely to be using higher nocturnal pressures. Finally, the authors consider the benefits and mechanisms of action for NIV without considering the most important factor—that it can provide total ventilatory support for many for decades. Other than for the recommendation of oxygen use and the other relatively minor points noted above, the article of Robert and Argaud [1] provides an excellent review for critical care physicians.

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References 

1. Robert D, Argaud L. Clinical review: long-term noninvasive ventilation 2007;11:210.
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2. Affeldt J. In: Round Table Conference on Poliomyelitis Equipment, Roosevelt Hotel, New York City, Sponsored by the National Foundation for Infantile Paralysis Inc. May 28-29. 1953;
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3. Bach JR, Alba AS, Saporito LR. Intermittent positive pressure ventilation via the mouth as an alternative to tracheostomy for 257 ventilator users. Chest. 1993;103:174–182
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4. Bach JR. The history of mechanical ventilation and respiratory muscle aids. In:  Bach JR editors. Noninvasive mechanical ventilation. Philadelphia: Hanley and Belfus; 2002;p. 45–72
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