Ventilator Waveforms and Scalars Lecture

Vocabulary terms and definitions regarding ventilator waveforms, scalars, loops, and mechanical ventilation modes derived from the student's lecture transcript.

Scalars

A series of curves on a ventilator screen that plot a specific value, such as pressure, flow, or volume, against time.

Loops

Ventilator graphics that plot a value against another value, such as a pressure-volume loop or a flow-volume loop.

PEEP

The medical term for an elevated baseline on a pressure waveform, standing for positive end-expiratory pressure.

Trigger

The fancy medical word for the start of inspiration on a ventilator graphic.

Peak Inspiratory Pressure (PIP)

The maximum pressure measured at the end of the inspiratory phase, often abbreviated as $PIP$.

Cycle

The point at which inspiration ends and the ventilator transitions into the exhalation phase.

Flow Scalar

A curve plotting flow against time that features a positive inspiratory phase and a negative expiratory phase.

Synchronicity

The condition in which a patient is not fighting the ventilator and their respiratory muscles are allowed to rest.

Square Waveform

A constant flow waveform delivered during volume control where the flow rate remains fixed throughout the duration of inspiration.

Decelerating Ramp

The default flow waveform for pressure control ventilation where flow starts high and gradually slows down as the lungs fill.

Time Constant

A calculation based on compliance and resistance that determines how long the inspiratory time should be set to ensure a full breath is delivered in pressure control.

Mean Airway Pressure

An important pressure value that drives recruitment and oxygenation by increasing the $FRC$ (Functional Residual Capacity).

Assist Control (AC)

A ventilator mode characterized by delivering only mandatory breaths, even if the patient triggers them.

IMV (Intermittent Mandatory Ventilation)

A ventilator mode that delivers a mix of mandatory breaths and spontaneous breaths.

CPAP

Normal unassisted spontaneous breathing on a ventilator at an elevated baseline, where every breath is patient-triggered using negative pressure.

Pressure Support

A pressure boost provided to help a spontaneously breathing patient overcome the increased airway resistance caused by the endotracheal tube.

Airway Resistance Rule for Pressure Support

A quick way to determine the initial setting for pressure support by calculating $PIP$ minus plateau pressure ($PIP - Plat$).

Tube Size Pressure Support Threshold

If a patient has an endotracheal tube smaller than $7.5$, the initial pressure support is typically set at $8$ instead of the standard $5$.