AGM Flashcards
High Pressure System (PSI)
750-2200 PSI
What are the high pressure systems on the AGM?
- Cylinders
- Hanger yoke
- Yoke block with check valve
- Cylinder pressure guage
- Cylinder pressure regulator
Cylinder reserve supply is for ________ use only
emergent
Tanks should ONLY be opened when
They are checked or pipeline is unavailable
What color tank is oxygen cylinder?
Green
What is the PSI of a full oxygen cylinder
1900-2200 PSI
How many L of gas is in a full oxygen tank?
660L
What color tank is air cylinder?
yellow
What is the PSI of a full air cylinder
1800 PSI
How many L of gas is in a full air tank?
600L
What color tank is Nitrous Oxide
Blue
What is the PSI of a full nitrous oxide cylinder
745 PSI
What state is nitrous oxide in when in cylinder
gas and liquid
How many L in a full tank of nitrous oxide?
1600L. (Will stay at 750 until liquid gone)
What is the Pin Index Safety System (PISS)
The pin arrangement matches holes in the yoke where cylinders are attached to the gas machine.
The PISS is a method to prevent misconnections.
What is the most fragile part of the cylinder?
The cylinder valve
What are the parts of the cylinder valve?
a body, the port where gas exits, a conical depression for the securing screw, PISS pins, and safety relief devices
Importance of hanger yoke
Orients the cylinder
Provides a gas tight seal
Ensures unidirectional flow
Contains a filter required by standard
Check valve to minimize transfilling
Intermediate Pressure System PSI
40-50 psi
What are the intermediate pressure systems on the AGM?
Ventilator power inlet Pipeline inlet Check valves Pressure gauges Flow meter valves Oxygen pressure-failure devices Oxygen second stage regulator Flush valve
Is oxygen stored as a gas or a liquid?
Pipeline - Liquid @ 184*C
Cylinder - gas
What is the PSI of oxygen in the pipeline?
50 PSI
Guideline for oxygen supply failure
Do not attempt to fix the oxygen analyzer. It must be trusted until proven inaccurate.
Turn on backup oxygen cylinder on machine fully, and disconnect pipeline. If inspired 02 does not increase, ventilate by bag mask.
Use low flow of oxygen.
Turn off ventilator and bag manually.
Call for help, calculate the time remaining on the cylinder.
Find out details of problem and how long.
DO NOT reconnect patient to pipeline unless it is tested.
Ventilate with an oxygen source or room air via bag valve mask.
5 tasks of oxygen in the AGM
- Proceeds to the fresh gas flowmeter
- Powers the oxygen flush
- Activates the fail safe device
- Activates oxygen low-pressure alarm
- Compresses the bellows of mechanical ventilators
Explain free floating valves
Moves in the direction or “push” of gas flow
Prevents gas from leaking out of system
Found in DISS and dual hanger yoke systems
Where do you find free floating valves?
oxygen flush (anesthesia panic button)
Where are the diaphragm valves located?
First stage regulator
Second state regulator
Low pressure system PSI
16 PSI
What are the low pressure systems on the AGM?
Flow meter tube
Vaporizers
Check valves
Common gas outlet
Where do you read a ball-float in the flow meter
middle of the ball
Where do you ready an arrow float
at the top of the float
What is the Thorpe Tube?
Gas specific and tapered with largest diameter at the top
What is the proportioning system?
“hypoxic guard”
Nitrous oxide and O2 chained together. That way you CANNOT give nitrous alone
How much concentration of gas is given through modern anesthesia gas vaporizers?
A constant amount, regardless of temperature change or flow
What will happen if the vaporizer is tipped then leveled out?
Liquid vapor will get into the vaporizer chamber and the carrier flow will be MORE agent to the patient. DO NOT USE after being tipped.
Inspiration and expiration check valves do what?
Permits direction of gas flow to and from the patient (unidirectional)
What does the APL (pop off) valve do?
Adjusts the limit of pressure in the patient circuit and rebreathing bag
On inhalation, gas flows through the
Inhalation check valve and the soda lime
Gas flows down through the soda lime from where?
Directly from the common gas outlet and from the rebreathing bag
On exhalation, gas flows through the exhalation check valve to where?
APL/rebreathing bag
What happens if the inspiratory valve sticks open?
The expiratory volume will exhaust through the inspiratory limb. The EtCO2 waveform will become elevated.
What happens is the expiratory valve sticks open?
Due to the path of least resistance, the inspired volume will not reach the ET tube but instead will bypass and exhaust through the expiratory limb.
APL (pop off valve) range
0-70
What does the APL valve control?
Controls how much pressure the patient gets.
What happens if you ventilate with to much pressure?
Will cause barotrauma. Normally ventilate at 25 but don’t go about 40 cm H2O
What is the open system?
No mask on face. Anesthetic to patient by insufflation. (Not in control how much anesthesia they get)
What is semi-open system?
Mask on face. Placed over face and pt spontaneously breathes inhaling anesthetic and room air. No rebreathing. CO2 accumulates under mask.. Portable/can use with any agent.
What is a unique hazard of the Bain Circuit?
is occult disconnection or kinking of the inner, fresh gas delivery hose. If this occurs, the entire corrugated limb becomes dead space. This results in respiratory acidosis which is unresponsive to increased minute ventilation.
How to perform a thicket test on the Bain Circuit
- Occlude the patient’s end of the circuit (at the elbow).
- Close the APL valve.
- Fill the circuit, using the oxygen flush valve.
- Release the occlusion at the elbow and flush. A Venturi effect flattens the reservoir bag if the inner tube is patent
Characteristics of Soda Lime
Mesh Size: 4-8
Absorptive Capacity: 14-23
Content: Ca Na K hydroxide
Advantage of heat and moisture exchanger (HME)
Heat and moisture exchangers (HME) are inexpensive, silent, easy-to-use devices that help retain heat and moisture within the anesthesia circuit
No need for water or electrical power source No risk of hyperthermia No risk of overhydration No risk of burns No risk of electrical shock.
Disadvantages of HME
not nearly as effective at warming and humidifying the patient’s airway as water-based, electrical devices. Increase deadspace and can increase the work of breathing. Airway obstruction can occur if the HME becomes blocked with fluid, blood, secretions, nebulized drugs
Hydrophobic HMEs
Have a hydrophobic membrane with small pores that is pleated to provide a greater surface area.
More effective at preventing transmission of Hep C
Hygroscoptic HMEs
Contain a wool, foam, or paper like material that is coated with a chemical that helps it to retain moisture. If become wet, they may lose their ability to filter airborne pathogens and airway resistance may increase substantially
What is the closed system?
Mask on face.
- Anesthetic agents are contained in the system and are not vented.
- Rebreathing of all gases ~ pop off closed (less pollution)
- Carbon dioxide absorber in system to neutralize CO2
- Unidirectional valves
- Flow 150-500 ml/min for physiologic requirements
- Flow 150-250 ml/min under anesthesia
- Unknown gas concentrations
Volume control ventilation
Delivers a constant tidal volume for each breath. Pressure will vary with changes in lung compliance and resistance.
Pressure control ventilation
Delivers a constant inspiratory pressure with each breath. Volume with vary with changes in lung compliance and resistance. (make sure watching TVs!)
SIMV (synchronized intermittent mandatory ventilation)
VCV or PCV breaths are provided at the preset rate. Spontaneous efforts can trigger these breaths. Spontaneous breaths that EXCEED the preset rate trigger are PSV.
Ve =
minute ventilation
Vt =
tidal volume
How do decrease FiO2
2L nitrous, 2L O2 = 50 FiO2
F=
rate
PIP (Pmax) =
Peak inspiratory pressure
Ascending Bellows (standing)
Bellows goes up with expiration and down with inspiration. Safety feature.
When using the O2 flush valve during inspiration, how much O2 is the pt getting?
600-1200 ml/sec
Potential problems with bellows driven machines
Tidal volume discrepancies between set and actual TV delivered to the patient.
Ventilator fresh gas coupling (gives even more TV if fresh gas flow is up. 6L flow, I:E ratio 1:2, rate 10 = extra 200ml/braeth
Advantages of modern piston driven AGMs
Quiet No PEEP Precision of tidal volume System controlled leak and compliance compensation Fresh gas decoupling
What is the compliance measurement used to calculate?
how much additional volume must be added to each breathe to deliver the set volume to the patient’s airway.
What does fresh gas decoupling do?
Ensures that the set and delivered tidal volumes are equal.
In fresh gas decoupling, where is the fresh gas diverted to?
diverted to the manual breathing bag, which remains in circuit during mechanical ventilation, and is not added to the delivered tidal volume.
How to respond to a sustained high pressure in breathing circuit
START at pt and work was back to vent.
- Switch to “bag mode” or manual ventilation
- Try manually ventilating the patient
- Assess and treat patient related causes
If high circuit pressure is sustained during manual ventilation
- Scavenger obstructed
- Scavenger relief valves have failed
- Disconnect scavenging system if possible
- Use ambulance bag to ventilate pt
If high circuit pressure is relieved after removing ventilator from system
- Ventilator relief valve is malfunctioning
- Ventilator must be repaired and is NOT TO BE USED!!
What is the scavenging system?
Receives waste gas from the AGM (APL) and the ventilator.
