How Ventilation Works Flashcards
One torr equals how many mmHg
One. they and equivalent
One ATM equals how many cmH2O
1034cmH20
At the start of a breath the alveoli is negative?
2-3
At the end of expiration the intrapleural pressure drops to
-5 cmH2O
At the end of inspiration the intrapleural pressure drops to
-10 cmH2O
What is the transrespiratory pressure
The pressure difference between the Aw opening and the body surface
(Pressure required to inflate the lungs during PPV)
Goals of mechanical ventilation
Provide O2
Provide alveolar ventilation
Avoid alveolar over distention
Maintain alveolar recruitment
Promote patient-ventilator synchrony
Avoid auto PEEP
Use the lowest possible FiO2
Define negative pressure
Generates a negative pressure at the body surface, transmitted to pleura space.
Parts of a ventilator
Power Supply
Battery management unit
Control board
User interface
Other technologies
What are the other technologies on the ventilator
Pressure sensor
Flow sensor
How are ventilators powered
Alternating current (A.C.) 120V
Direct current (DC) 12V battery
(Short term transport or backup power)
What do electrically powered ventilators work off
Controlled motors
Electromagnets
Potentiometer
Rheostats
Computers
Pneumatically powered ventilator components
Needle valve
Venturi entrainment
Flexible diaphragms
Spring loaded valves to control flow
When is Pneumatically powered ventilators used
Transport, MRI, or power fail
Types of battery powered ventilator
Bear 33
PB 2801 Companion
What does the control system do
Interprets the operators settings and regulates the desired outcome
How does the open loop system work
Not a microprocessor (unintelligent)
Cannot respond to changing conditions
How does a closed system work
Compares set control and adjust occurring to patients changes. (Intelligent)
What does the compressor in the ventilator do
Reduces internal volumes to generate a positive pressure at the
Types of compressors
Piston drive
Use rotating blades
Moving diaphragms
Bellows
What are the ventilator displacement designs
Bellows and concertina bags
How does a ventilator Rotary drive piston bellow work
Lelectric motor rotated a drive wheel
Creates a sinusoidal flow waveform (increases at the start of inspiration and tapers)
What types of ventilator concertina bags are there
Linear drive piston:
Electrical motor connected by gears to pistons
Springloaded bellows
Adjustable spring on top of a bellows applies force
(No longer manufactured)
How are solenoid valves controlled
Electrical timers
Microprocessor
Manual operation or pressure
What do fluidic ventilators rely on
Wall attachment and beam deflection
Are analogous of electronic logic circuits (used only occasionally)
Schema of modern mechanical ventilators
Electronically and Pneumatically controlled
Sensors measure pressure and flow
Microprocessor control Inspiratory and expiratory valves
Expiratory valve controls PEEP
Define NIV
Delivery of positive pressure through a natural aw
Evidence for the indication of HHFNC
Acute hypoxemia respiratory failure
Risk of post extubation hypoxemic respiratory failure
Unsupported Evidence for indication of HHFNC
COPD
Asthma
Cardiogenic pulmonary edema
What does BiPAP stand for
Bilevel Positive Aw Pressure
Indication for CPAP
Acute care
(Decreases preload and after load)
Need a adequate spontaneous ventilation workload
What should the CPAP initial pressure be
5-10cmH2O
Where can the FiO2 be set at the start of CPAP
100% and can be tapered down
Parameters for OSA
A reduction in ventilation of at least 50% that results in a decrease of arterial saturation of 4-more percent. Caused by partial aw obstruction
Equation of motion
Pmus+Pvent= resistance (flow) + elastance (volume)
