Inexsufflator

Abstract

A manual inexsufflator including a standard mechanical ventilator, a medical suction unit, and a piston-like sliding valve mechanism which connects a patient ventilation interface with either the ventilator or the suction unit. By sliding the valve mechanism in and out the user selectively connects the patient to either the ventilator, for purposes of insufflation, or the suction unit, for purposes of exsufflation. The ventilator may generate expiratory positive airway pressure between inexsufflation cycles.

Description

CROSS-REFERENCE TO PREVIOUS APPLICATIONS [0001] This application is a continuation-in-part application of and claims priority from U.S. Patent 09 / 975,943, filed Oct. 15, 2001.FIELD OF THE INVENTION [0002] The present invention relates generally to respiratory apparatus, and particularly to an inexsufflator useful, for example, in clearing respiratory secretions from airways. BACKGROUND OF THE INVENTION [0003] Patients suffering from weakness of the muscles of the thoracic cage and diaphragm, as may occur in, for example, Duchenne Muscular Dystrophy or Cervical Spine Injury, are often unable to cough effectively, if at all. Due to their inability to clear respiratory secretions from their lower respiratory tract, retained secretions may develop in their lungs. As retained secretions constitute a focus for infection, these patients are at high risk of developing severe, and potentially fatal, pneumonia, and are thus in need of assistance in expectorating their respiratory secretions. ...

AI Technical Summary

Benefits of technology

[0020] The present invention seeks to provide a manual inexsufflator that is simple and inexpensive, yet efficient and effective in artificially reproducing a coughing action to clear respiratory secretions from lungs and airways.

[0024] The piston-valve establishes airflow continuity between the patient interface and, depending on the valve's orientation (i.e., piston “pushed in” or piston “pulled out”), either the ventilator or the suction unit, both of which operate continuously. The operator of the inexsufflator causes the device to cycle between insufflation and exsufflation by manually pulling the piston of the valve outward (when the ventilator is delivering a breath) and then pushing it inward (at the moment that mechanical inhalation terminates). In so doing, the operator selectively and exclusively establishes airflow continuity between the patient and either the mechanical ventilator (thus achieving insufflation) or the suction unit (thus achieving exsufflation) in an alternating manner respectively. Between inexsufflation cycles the piston is pulled outwards, so that the ventilator delivers PEEP to the patient until the onset of the next mechanical breath. As such, intra-alveolar pressure does not remain at zero after exsufflation has terminated, thus preventing alveolar or airway collapse

[0025] The “in-out” movement of the piston-valve parallels the arm action of an abdominal / chest thrust as is done for purposes of assisted coughing. Thus, an operator performing an abdominal thrust with one hand while initiating a mechanical exsufflation with the other hand performs the same gross motor movement with each hand simultaneously. This uniformity of hand movement facilitates exact coordination of the two actions by the operator, thus enhancing the efficacy of the procedure.

Problems solved by technology

Patients suffering from weakness of the muscles of the thoracic cage and diaphragm, as may occur in, for example, Duchenne Muscular Dystrophy or Cervical Spine Injury, are often unable to cough effectively, if at all.

As retained secretions constitute a focus for infection, these patients are at high risk of developing severe, and potentially fatal, pneumonia, and are thus in need of assistance in expectorating their respiratory secretions.

If the degree of muscle weakness is severe, however, the patient will require mechanical assistance to achieve adequate pulmonary toilet.

There are several drawbacks to endotracheal suction as a means for clearing respiratory secretions.

The procedure is invasive, thus requiring sterile technique for its performance, and may cause physical trauma to, or infection within, the patient's airways.

Moreover, this technique can only be performed on those patients who are already intubated or tracheostomized, and is not relevant to the majority of patients who do not have instrumentation within their respiratory tract.

Many patients in need of an inexsufflator have weakness of their facial and glossopharyngeal muscles in addition to the weakness of their chest wall muscles, and they typically are unable to “hold in” a deep breath for a significant period of time.

The electrical timing mechanism within automatic inexsufflators, and the mechanism for generating positive-pressure airflow into the patient, makes these devices both electronically complex and expensive.

The cost of such devices (approximately $5000 in 2002) is of particular importance because many patients in need of an inexsufflator are concurrently in need of a similarly expensive mechanical ventilator for purposes of mechanical ventilation via an invasive or noninvasive ventilation interface, as their chest wall muscle weakness limits not only their ability to cough, but also their ability to breath adequately and independently.

Such patients, who are often already using a mechanical ventilator, are thus compelled to acquire an additional expensive ventilatory device if they wish to perform mechanical inexsufflation.

Standard inexsufflators, however, are known to suffer from several deficiencies:

1) The equilibration of intrapulmonary pressure with atmospheric pressure that occurs during the expiratory pause phase of the respiratory cycle impedes effective secretion clearance.

2) Standard inexsufflators are comprised of a built-in mechanism for generating airflow in two directions (both into and out-of the patient's lungs), which is mechanically complex.

As such, standard inexsufflators (both manual and automatic versions) are expensive, with even manual inexsufflators costing approximately $3000 in 2002.

3) It is difficult for a caregiver performing the manual assisted cough technique simultaneously with mechanical inexsufflation to achieve optimal coordination with a manual inexsufflator.

Precise coordination of left and right hand movements, which is essential for achievement of effective cough flows, is particularly difficult when each hand is performing a different gross motor movement.

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