Ventilator-Assisted Living©

Spring 1993, Vol. 7, No. 1


The Cof-flator Revisited*

Judith R. Fischer

Originally produced by the O.E.M Corporation, the Cof-flator was a wonderful device used by many respiratory polio survivors in the late 1950s and 1960s to help them produce a good cough and clear secretions. Unfortunately, the Cof-flator became an endangered species, protected largely by polio survivors who diligently maintained their machines. Now, however, the J.H. Emerson Co. is offering the Emerson In-Exsufflator to help individuals without tracheostomies clear secretions. The equipment gradually applies a positive pressure to the airway, then rapidly shifts to negative pressure. The rapid shift in pressure, via a face mask, produces a high expiratory flow rate from the lungs, simulating a cough. This technique is referred to as “exsufflation with negative pressure.”

People who might benefit from the use of the In-Exsufflator include anyone with an ineffective cough due to muscular dystrophy, ALS, myasthenia gravis, high level SCI, post-polio, etc. The In-Exsufflator may also treat ineffective cough due to emphysema, cystic fibrosis, bronchial asthma, and bronchiectasis.

Cost of the machine is $2,500, and an individual must have a physician’s prescription to order one. Equipment specifications can be obtained from J.H. Emerson Co., 22 Cottage Park Ave., Cambridge MA 02140, 800-252-1414.

The following excerpt from "Intermittent positive pressure ventilation via the mouth as an alternative to tracheostomy for 257 ventilator users” by John R. Bach, MD; Augusta Alba, MD; and Louis Saporito, RRT, emphasizes the efficacy of mechanical exsufflation. The article appeared in Chest, January 1993, pp. 174-182, and is reprinted with permission of Chest.

See below for updated information:

… Airway secretion management, particularly during respiratory tract infections (RTIs), is the most frequent reason that patients with chronic alveolar hypoventilation are hospitalized or intubated. This is particularly true for patients receiving no or only part-time ventilatory aid. Individuals receiving ventilation either intubated or with indwelling tracheostomies, however, have increased risk of nosocomial morbidity and mortality. This study implies that individuals using noninvasive methods of ventilatory support may also experience increased risk of nosocomial morbidity and mortality, particularly when associated with general anesthesia and surgery. We have noted this to be true especially when such procedures are undertaken without the intimate participation of clinicians proficient in using noninvasive respiratory muscle aids. Lack of clinician familiarity with and confidence in using noninvasive techniques leads to patients remaining incubated for unnecessarily long postoperative periods.

... By avoiding tracheostomy with the use of noninvasive aids, natural airway secretion clearance mechanisms remained intact. This made airway secretion management a problem only during intercurrent RTIs or following intubation for surgery. Along with the use of mechanical exsufflation, the effective use of manually assisted coughing techniques can be important for avoiding pulmonary complications. For individuals with less than 1 L of vital capacity, the use of manually assisted coughing should be preceded by a glossopharyngeal breathing-assisted deep breath or an assisted deep insufflation with the use of a manual resuscitator, positive pressure blower (Zephyr, LIFECARE, Inc., Lafayette, Colo), portable ventilator, or intermittent positive pressure breathing machine, to maximize peak cough expiratory flows. Since manually assisted coughing techniques cannot be used efficiently during tracheostomy IPPV and are difficult to employ effectively even in the presence of a plugged tracheostomy tube, the techniques have been largely forgotten and widely underutilized. The minimum of 5 to 6 L/s of peak cough expiratory flow necessary for airway secretion clearance, however, can usually readily be provided for patients with neuromuscular ventilatory failure by using these techniques. In the presence of severe scoliosis or during severe RTIs, manually assisted coughing is often inadequate and mechanical exsufflation becomes vital.

The manufacture of mechanical exsufflators ceased in the early 1960s, and exsufflators have only recently become available (J.H. Emerson Co., Cambridge, Mass). Access to these devices has been restricted, therefore, to the relatively few individuals who have owned and maintained them over the years and to patient care networks in which the devices are shared and made available to patients in time of need. During use, the success of mechanical exsufflation can be observed objectively by the appearance of mucus in the patient’s mouth or the excufflator mask, the increase in oxyhemoglobin saturation during and immediately following use by auscultation, and the increase in pulmonary volumes observed with the clearance of mucous plugs. In addition, 6 to 1 1 L/s of peak expiratory flow can be conveniently and reliably generated during mechanical exsufflation. Clinical and physiological studies demonstrated the safety and efficacy of this technique in the 1950s, and we have come to rely on it to permit continuation on noninvasive ventilatory support during RTIs, for achieving earlier extubation of ventilator-assisted patients, and for preventing postoperative pulmonary complications particularly following abdominal surgery.

We are currently surveying the number of hospitalizations and serious pulmonary complications, including atelectasis and pneumonia, in 24-h noninvasive ventilatory support users, including some patients who use body ventilators as part of their daily regimen. Ninety-five such individuals for whom reliable data could be obtained reported 41 hospitalizations for pneumonia or atelectasis and 134 total pulmonary hospitalizations, mostly for management of intercurrent upper RTIs, in 1,376.8 patient years of 24-h use. This amounted to 0.43 percent serious pulmonary complications and 1.41 hospitalizations over 14.5 years of 24-h use of noninvasive ventilatory support. These figures, which thus far are significantly better than for patients using nocturnal ventilatory aid only, indicate that irrespective of the extent of ventilatory insufficiency, patients for whom alveolar ventilation is maintained within normal limits 24 h/d and who have access to effective noninvasive airway secretion clearance methods, have very low incidence of serious pulmonary complications. Since none of these patients received supplemental oxygen therapy, these results call into question the all-too-common practice of treating patients with chronic alveolar hypoventilation with oxygen therapy rather than ventilatory assistance.

In conclusion, the use of noninvasive IPPV techniques, and in particular mouth IPPV that can be effective and practical for both daytime and nocturnal ventilatory support, can indefinitely spare many individuals with ventilatory insufficiency from intubation or tracheostomy for ventilatory support. This can allow many to effectively use glossopharyngeal breathing for ventilator-free time, to provide perfect security in the event of sudden ventilator failure, and to give deep breaths for assisted coughing. Access to reliable and effective manually assisted coughing or mechanical exsufflation is also critical for the long-term success of an entirely noninvasive ventilatory support regimen.

*Note: J.H. Emerson Company's newer version of this equipment is the CoughAssist™.

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