Biomedical subjects
Publications and source records attributed to M J Banner.
We found that the transport of gases in oscillating gas columns was proportional to oscillation frequency and the square of oscillation amplitude. When these results were applied to high-frequency oscillation and high-frequency jet ventilation in dogs, alveolar ventilation was proportional to frequency and to the square of tidal volume, and inversely proportional to anatomic dead space.
An Emerson 3-PV ventilator was modified to function as a model for spontaneous ventilation. Respiratory rates, tidal volumes, inspiratory/expiratory time ratios, and flow rates were adjusted to produce sinusoidal inspiratory and expiratory flow patterns that mimicked physiologic ventilation.
It was shown in dogs that intrapulmonary physiologic shunt (Qsp/Qt), arterial oxygen tension (PaO2), total static respiratory compliance (CT), oxygen delivery (O2AV), cardiac output (Qt), and arterial minus end-tidal carbon dioxide gradient (PaCO2-PetCO2) undergo statistically significant deterioration when oleic acid is injected into the pulmonary artery. Positive end-expiratory pressure (PEEP) therapy reduced Qsp/Qt and PaCO2-PetCO2 gradient and increased PaO2. The CT did not show any consistent pattern of improvement with the application of PEEP. The Qt and the O2AV progressively decreased as PEEP was increased. The application of additional PEEP beyond that which minimized the PaCO2-PetCO2 gradient produced a statistically significant increase in the PaCO2-PetCO2 gradient, but this was not reflected by concomitant changes in Qsp/Qt or PaO2 in spite of a further decrease in Qt. Thus, the PaCO2-PetCO2 gradient may be a more sensitive indicator of excessive PEEP than is Qst/Qt or PaO2, since it should be smallest when there is maximal recruitment of perfused or functional gas units without overdistention of alveolar areas contributing to dead space. Also, the use of the PaCO2-PetCO2 gradient permits the rapid titration of PEEP without the need for a pulmonary artery catheter.
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Accurate assessment of mean airway pressure (PAW) during controlled mechanical ventilation (CMV), intermittent mandatory ventilation (IMV), continuous positive airway pressure (CPAP), and expiratory positive airway pressure (EPAP) or spontaneous PEEP (sPEEP), or combinations thereof can be electronically determined with the Novametrix Pneumogard Model 1230 Ventilator Monitor. Measurement of PAW provides information on the interactions of airway pressure hemodynamics and respiratory function.
The authors have developed a new method for independent lung ventilation (ILV). After lung isolation with a double-lumen endotracheal tube, one ventilator with two subunits controls independent lung tidal volume (VT) and PEEP to each lung. A modified bird Mark 2 ventilator serves as a pneumatically powered timer activating two sets of parallel inspiratory-expiratory flow cartridges. Intermittent mandatory ventilation (IMV) with PEEP or controlled mechanical ventilation (CMV) with PEEP can be provided. This ventilator has been successfully used to treat patients with severe unilateral disease. Desirable qualities include simplicity of operation, availability of parts, and low cost.
A bird Mark 8 ventilator has been modified by a time cycled servo mechanism to function as an inexpensive ventilator with high peak pressure capabilities. This system was designed to deliver IMV-PEEP therapy at levels not usually available on commercial ventilators. IMV rate can be varied from 1 to 60/min, Vt from 0.1 to 2 liters. Inspiratory pressure in excess of 200 torr and PEEP from 1 to 25 torr can be generated. Modifications to the Mark 8 cost $750.00. The ventilator has been successfully used in over 100 patients. Transport and operating room use are facilitated because it is solely pneumatically powered. Thus, an inexpensive, reliable and versatile ventilatory support system with high peak pressure capabilities has been developed and successfully used.