Articles: ventilators.
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Trans Am Soc Artif Intern Organs · Jan 1984
Extracorporeal gas exchange, lung transplantation, and the artificial lung.
The potential for lung damage from mechanical ventilation may be much greater than has been realized in the past. Prior studies of extracorporeal support in adults were carried out after patients had been subjected to high airway pressure and hyperventilation for several days. The studies by Gatinoni supported by Kolobow would suggest that earlier application of extracorporeal gas exchange to remove CO2 may be more effective in salvaging the lung, particularly if applied before ventilator-induced lung damage has occurred. ⋯ However, lung transplantation for acute respiratory failure in a patient who is being supported with ECMO is not recommended. The feasibiilty of an implantable lung has been demonstrated in animals for short periods of time. Continuing studies in this area should be encouraged, particularly before the establishment of a lungless animal preparation to determine some of the nonrespiratory functions of the lung.
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Compression of gases (Boyle's law) and circuit compliance are major determinants of anesthesia circuit function. The materials of which circuits are constructed and the use of heated humidifiers may result in clinically important variations in delivered minute ventilation (VE) secondary to variations in compression volume. We examined eight anesthetic circuits both with and without a heated humidifier in an in vitro setting. ⋯ Pediatric circle systems were intermediate and adult circle systems had the largest compression volume and were the least efficient. Humidifiers uniformly increased compression volume. The following conclusions were drawn: 1) the anesthetic circuit, its material, and the pressure at which it operates are important determinants of circuit function; 2) humidifiers increase compression volume; 3) Mapleson D circuits had the lowest compression volume and therefore were the most efficient; 4) highly compliant adult circuits may result in compression volume losses that exceed the tidal volume of a pediatric ventilator; 5) humidifiers with low volume and rigid tubing should have the least effect on minute ventilation; and 6) highly compliant adult circuits when used in the care of infants and small children must be used with caution.
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Meditsinskaia tekhnika · Nov 1983
[Intermittent positive pressure ventilation of the lungs with the PO-6 respirator].
A modified Soviet ventilator PO-6 is presented suitable for performing intermittent mandatory ventilation (IMV) in combination with continuous positive airway pressure ventilation (CPAP). Some requirements for hardware necessary to realize IMV and CPAP modes are specified, and a critical evaluation of capabilities and disadvantages of the modified design is given in a view of these requirements.
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A ventilator, of new design, is described which has been evaluated on a lung model and in animals. It is simple, versatile, inexpensive and easy to sterilize. A single breathing tube is used in which the respiratory gas is introduced near the patient's airway while a jet in a more distal part of the tube drives the respiratory gas into the patient's lungs. ⋯ It can be used for any age group with any desired respiratory gas, and is suitable for use in the operating theatre and the intensive care unit. As there are no valves in the breathing system, which is open to the atmosphere at all times, complicated systems for synchronizing the machine with spontaneous breathing are not required. PEEP, NEEP, CPAP and IMV are applied easily.
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Comparative Study
A comparison of the oxygen cost of breathing between a continuous-flow CPAP system and a demand-flow CPAP system.
We undertook a study to measure the difference in work of breathing, as reflected by oxygen uptake (VO2) and carbon dioxide production (VCO2), between that on a continuous-flow CPAP system (Emerson IMV) and that on a demand-flow CPAP system (Bennett MA-2). A specially designed valve permitted the isolation and collection of expired gases from the Emerson IMV/CPAP ventilator. Ten patients receiving CPAP therapy were selected for study. ⋯ Analyses of VO2, VCO2, respiratory quotient, minute ventilation, tidal volume (VT), respiratory rate, and FIO2 were made serially at approximately 45-second intervals for 8 minutes. A comparison between the Emerson continuous-flow CPAP system and the MA-2 demand-flow CPAP system revealed that with the MA-2 the mean values for VO2, VCO2, and VT were, respectively, 16.3%, 12.6%, and 6.4% higher, a statistically significant difference. We believe that this difference was probably due to the additional effort required of the patient on the MA-2 to open and close the demand valve.