ADD THESE TO YOUR MECHANICAL VENTILATION STUDY GUIDE 15. INSPIRATORY FLOW RATE ⭐ What is inspiratory flow? Flow = how FAST the ventilator delivers the breath. Usually expressed in L/min. For volume control: Flow (L/min) = VT (L) ÷ Ti (sec) × 60 Example: VT = 600 mL = 0.6 L Ti = 1 second 0.6 ÷ 1 × 60 = 36 L/min A constant inspiratory flow around 60 L/min is commonly used when assessing mechanics in volume assist-control, although actual appropriate flow depends on the patient’s needs. HIGH-YIELD FLOW RULE

COPD

Chronic Obstructive Pulmonary Disease, characterized by a need for more time to exhale.

Air trapping

A condition where air becomes trapped in the lungs, often due to inadequate exhalation.

Dynamic hyperinflation

An increase in lung volume due to inadequate exhalation, commonly seen in COPD patients.

Auto-PEEP

Positive end-expiratory pressure that occurs when exhalation is incomplete, leading to increased work of breathing.

Volume Control

A mode of mechanical ventilation where tidal volume is set by the clinician.

Pressure Control (PC)

A ventilation mode where pressure is controlled; VT is variable depending on lung mechanics.

Pressure Support Ventilation (PSV)

A spontaneous breathing mode that assists patients by providing pressure-limited support for initiated breaths.

Tidal Volume (VT)

The volume of air delivered to the patient with each breath.

Respiratory compliance

The measure of the change in lung volume per change in pressure; important in determining VT in pressure control ventilation.

Cycling criteria

The conditions under which a ventilation support mode stops inspiration and begins expiration.

High pressure alarm (PIP)

An alarm indicating increased pressure, which may suggest resistance or compliance issues.

Low pressure alarm

An alarm signaling potential leaks or disconnections in the ventilatory circuit.

Barotrauma

Injury to the lungs from excessive pressure during mechanical ventilation.

Ventilator-induced lung injury (VILI)

Injury caused by mechanical ventilation, including barotrauma, volutrauma, and atelectrauma.

SCOOPED EXPIRATORY FLOW-VOLUME LOOP

A characteristic waveform indicating obstruction, commonly seen in COPD or asthma patients.

Pressure-time waveform

A graphic representation that shows the pressure delivered over time, reflecting patient-triggered breaths.

Flow starvation

Condition where patient demand for inspiratory flow exceeds the ventilator's ability to deliver it.

PEEP (Positive End-Expiratory Pressure)

A mode of ventilation that maintains positive pressure in the airway at the end of expiration, preventing alveolar collapse.

AARC recommendation for VT

Assessing VT at 4-8 mL/kg predicted body weight for lung-protective ventilation.

Ventilator graphics

Visual representations (pressure, flow, volume curves) used to assess patient-ventilator interactions and efficacy.