Test 1 part VII (AM) Flashcards
Adjusts the ratio of vaporizing chamber flow to bypass flow and guarantees a constant vaporizer output over a wide range of temperatures (bimetallic strip or expansion element).
Temperature Compensating Valve
Constructed of metals with high thermal conductivity (copper, bronze) to minimize heat loss
Temperature Compensating Valve
If the temperature of the liquid anesthetic decreases, the temperature element will _____ FGF into the vaporizing chamber to offset the decrease in vapor pressure.
Increase
What is the purpose of the baffles and wicks?
Increase surface area and turbulence to cause 100% saturation.
________ is required to guarantee a consistent vaporizer output!!
Full Saturation
How do variable bypass (AKA flowover, temp-compensated) vaporizers work?
Fresh gas flows through either the vaporizing chamber or the bypass chamber. A small portion of the Fresh gas flows through the vaporizing chamber, over a series of baffles and wicks to get 100% saturation. The fully saturated concentration of flowover gas is diluted with the balance of bypass flow.
What is the splitting ratio?
Carrier flow:bypass flow
some fresh gas encounters the anesthetic
while the rest bypasses the anesthetic liquid.
Flows less than ____ mL or greater than ____ L can reduce vapor output
Less than 200 mL; greater than 15 L
Why does Desflurane need a special vaporizer?
It’s high VP
The Tec 6 is a dual-circuit vaporizer, heated to ____ degrees and pressurized to ___ atm.
39 degrees, 2 atm
How does the Tec 6 Injector (AKA Injector Vaporizer) work?
The fresh gas flow never bypasses or flows over liquid desflurane. There is no contact between them. An appropriate amount of desflurane vapor is injected into the FGF right before the vaporizer outlet.
What are the hazards of vaporizers?
- Incorrect agent administration
- Tipping (increase vaporizer output)
- Overfilling
- Reliance on breath-by-breath gas analysis
- Leaks (esp loose filler cap)-only detected when vaporizer turned on
- Electronic failures
What are the two most common reasons for an increase in inspired CO2?
- The absorbent granules have been exhausted (soda lime)
- The unidirectional valves are faulty
What should you do if inspired CO2 of more than 1-3 mmHg is detected on the capnograph?
Increase FGF to 5-8 L/min (converts the system to semi-open and rebreathing of exhaled gases is minimized).
What should you do if elevated inspired CO2 persists in spite of the higher FGF?
The unidirectional valves are likely to be incompetent.
What is the neutralization rxn associated with Soda Lime CO2 Absorption?
- CO2 + H2O → Carbonic acid (H2CO3)
- H2CO3 + 2 sodium hydroxide (NaOH) → Sodium Carbonate (Na2CO3) + 2 H2O + heat
- Na2CO3 + calcium hydroxide (CaOH2) → calcium carbonate (CaCO3) + NaOH
What is necessary with CO2 Absorbent to optimize resistance to flow & absorption efficiency?
- Water content between 13-20%
- Granule size 4-8 mesh
New soda lime removes the what?
Strong alkali component of Na & K activated soda lime
Associated with decreased formation of compound A with sevoflurane & decreased formation carbon monoxide with desflurane or isoflurane & minimal destruction inhaled agents
Calcium Hydroxide Lime
When the pH falls below ____, the indicator dye will change to ______ color.
10.3; blue/purple
True/False: When the color changes, the CO2 absorbent is no longer able to effectively neutralize CO2.
True
Does soda lime regenerate?
No (the color will change back to white when you stop using it, which is misleading)
Occurs when the absorbent is devoid of water. End up with the production of Carbon Monoxide (CO) or Compound A.
-Low FGF preserves the H2O content in soda lime
Desiccation
Which anesthetic agent produces the most carbon monoxide?
Desflurane > Isoflurane
Sevoflurane produces Compound A
What are the early clinical signs of CO2 absorbent exhaustion?
- Increase in partial pressure of EtCO2
- Respiratory Acidosis with hyperventilation
- Signs of SNS activation (flushing, sweating, cardiac irregularities)
- Increased surgical site bleeding
- Color of indicator
What are late clinical signs of CO2 absorbent exhaustion?
- Increased HR & BP
- Dysrhythmias
In clinical practice, what are the primary signs of CO2 absorbent exhaustion? (Most symptoms are masked in the anesthetized patient)
- Increased FiO2
- Indicator color change
The collection of waste anesthetic gasses from the breathing circuit & ventilator for removal from the OR.
-The gas collecting assembly is located at the APL Valve or Ventilator Relief Valve
Scavenging
How much must be scavenged every minute?
An amount equal to the FGF
What is the most important component of the scavenger system?
The interface (between the breathing circuit and wall suction), because it protects the patient’s airway from excessive buildup of positive pressure, and from exposure to suction.
What is an active scavenging system?
Suction is applied to the interface.
-Risk for negative pressure to potentially be applied to the patient circuit.
-Most current anesthesia ventilators have an automatic pop-off valve built in, so that gas is exhausted only at end-exhalation.
What is a passive scavenging system?
Positive pressure of fresh gas. No dedicated suction line for the scavenger.
Hospital accreditors currently require ______ scavenging in the United States.
Active scavenging
A scavenging interface that is open to the atmosphere.
-There are no valves
-Only works with active systems, reservoir required, higher risk of exposure to waste gas. Requires appropriate suction to work. If suction isn’t working, all patient exhalations and waste gas will be released into the OR.
-Patient safety advantages (safer than closed, no barotrauma)
-Supplied on all new workstations
Open Scavenging Interface
A scavenging interface that contains valves, is used with active disposal systems (but can do passive as well), and must have positive and negative pressure relief valves.
Closed Scavenging Interface
Allows room air to enter the interface when suction is excessive.
Negative Pressure Relief Valve
Opens and releases waste gases into the OR air.
Mandatory for all closed interfaces.
Positive Pressure Relief Valve
