The Science Journal of the American Association for Respiratory Care

1998 OPEN FORUM Abstracts

THE EVOLUTION OF CARDIOPULMONARY DEVICES

Forrest M Bird, M.D., PhD., ScD. Bird Institute of Biomedical Technology. Sandpoint, Idaho

The purpose of this discussion is, to allow the Respiratory Therapist to glean a sense of understanding, relative to how the corpus of rationality was derived, which determined "in part" the historical design of Medical Respirators later restated as Ventilators.

In the nineteen forties and fifties and well into the sixties and beyond, "tracheal positive pressure" Medical Respirator innovations were generally based upon the "educated hand" of the Anesthetist. In other words, the goal of all ethical mechanical ventilatory devices, were to automatically perform the manual function of the Skilled Anesthetist's hand on the Anesthesia Bag.

There were always two Classical general opinionated design logic's applied to Mechanical Ventilatory Devices, they were from:

1. The Engineer's point of view, (without a Pathophysiological background), who looked at the mechanical ventilation of the lung as "cycling" a Tidal Volume of respiratory Gas in and out of the lungs at controllable Rates. The Patient was then forced to comply with the Mechanical design limitations of the Ventilatory Device.

2. The Physician's point of view, (without a Technological background), realized the Mechanical Ventilation of the Lung, had to Comply with each Patients existing Pathophysiology for maximum Clinical efficacy, as well as, for Control over potential Barotrauma.

It became obvious, in order to conceive and design a Universal Mechanical Ventilator, there were several key basic rationales, which had to be considered, they were:

1. Does the Ventilatory Device effectively "Comply to Existing Pathophysiology", or does it require the routine "Sedation of the Patient" to prevent the Patient from "Fighting the Mechanical Schedules", being forced upon the Physiological Structures?

2. Has the Design Concept, considered the prevailing "Professional Limitations" of the Clinicians, Administering to the Patient.

During the formative post "World War Two years", of Ventilatory Device Concepts and Designs, which were based upon a controlled Tracheal Positive Pressure, there were three major Individual Contenders. They were; Emerson, Bennett and Bird, who conceived the major innovative processes, enabling the mass production of reliable Ventilatory devices. Later as Corporate Interests absorbed "Individualistic Talents", the "straight forward" design concepts of the first generation of (primary pneumatic) Medical Respirators were eclipsed by the evolving highly sophisticated (electronic) Ventilators. While the electronic Ventilators became increasingly sophisticated, they often ignored provisions for bilateral gas distribution, Aerosolization of Medications and Wetting Agents, Demand CPAP, as well as Assisted Ventilation for the enhancement of Spontaneous Respiration. In other words, many proven therapeutic regimes were denied because they would interfere with the assessment of "TIDAL VOLUME MONITORING".

The 44th International Respiratory Congress Abstracts-On-DiskĀ®, November 7 - 10, 1998, Atlanta, Georgia.

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