RT Book, Section A1 MacIntyre, Neil A1 Branson, Richard D. A2 Tobin, Martin J. SR Print(0) ID 57066056 T1 Chapter 15. Feedback Enhancements on Conventional Ventilator Breaths T2 Principles and Practice of Mechanical Ventilation, 3e YR 2013 FD 2013 PB The McGraw-Hill Companies PP New York, NY SN 978-0-07-173626-8 LK accessmedicine.mhmedical.com/content.aspx?aid=57066056 RD 2024/10/05 AB The first generation of positive-pressure mechanical ventilators were simple high-pressure gas regulators on which clinicians could set the circuit pressure and the breathing frequency. In the middle of the twentieth century, more sophisticated devices appeared that allowed direct clinician control of flow and volume along with breath timing and expiratory pressure. As ventilator design improved and microprocessors became available, feedback mechanisms appeared that could provide automatic adjustments in these set variables depending upon a variety of conditions.1 A simple example was the use of a patient-effort sensor to adjust the number of mechanical breaths provided during assist-control modes or synchronized intermittent mandatory ventilation.2–4 A variation on this breath rate feedback mechanism was mandatory (or minimum) minute ventilation, which used minute ventilation to adjust the number of positive-pressure breaths delivered.5 At the same time, the development of flow control valves that could be adjusted based on a clinician-selected airway-pressure target appeared.6–9 This gave clinicians the choice of using either set flow-volume-targeted modes (volume assist-control ventilation; volume-targeted synchronized intermittent mandatory ventilation [volume SIMV]) or pressure-targeted modes (pressure-targeted assist-control ventilation [PACV]; pressure support; pressure SIMV). Taken together, these flow-targeted, volume-targeted, and pressure-targeted strategies comprise what is commonly referred to today as “conventional” mechanical ventilation.