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# Airway Pressures This document discusses airway pressures during mechanical ventilation. ## Flow A table displays the flow of air into and out of the lungs during different stages of inspiration and expiration: | Stage | Flow In | Flow Out | |---|---|---| | Inspiration | Into lungs | No flow |...

# Airway Pressures This document discusses airway pressures during mechanical ventilation. ## Flow A table displays the flow of air into and out of the lungs during different stages of inspiration and expiration: | Stage | Flow In | Flow Out | |---|---|---| | Inspiration | Into lungs | No flow | | End-inspiration | 0 | 20 | | Expiration | No flow | Out of lungs | | End-expiration | 0 | 0 | *In this table, values are in cm H₂O.* ## Peak Inspiratory Pressure (PIP) The peak inspiratory pressure (PIP), recorded as the maximum pressure during one respiratory cycle, is usually measured at the end of inspiration. The pressure readings in a table are used for illustrative purposes; the barometric pressure is set at 0 cm $H_2O$. ## Pressures in Mechanical Ventilation The paper explains how airway pressures are controlled during mechanical ventilation. * **Pressure-controlled ventilation:** In this process, the peak inspiratory pressure (PIP) is set according to the estimated tidal volume requirement of the patient, and the inspiratory phase stops when the preset pressure is reached, potentially leading to smaller volumes received than expected. This can occur in conditions with low compliance (lung's ability to stretch) or high resistance (airway resistance). * **Volume-controlled ventilation:** In this setting, the tidal volume is preset, and the ventilator adjusts the pressure to deliver this volume, resulting in a variable PIP. ## Table 2-3: Conditions Limiting Volume Delivery | Conditions | Examples | |---|---| | Peak inspiratory pressure reached too soon | Airway obstruction, Kinking of ET tube, Bronchospasm | | Unable to reach peak inspiratory pressure| Low lung compliance, Pressure limit set too low, ET tube cuff leak, Ventilator circuit leak | *Note: ET tube refers to endotracheal tube.* **Disclaimer:** Information in the document was extracted and summarized from the provided image. There may be some slight formatting discrepancies in the markdown table structure.