Module 4 Scavenger Systems Flashcards
Barotrauma
Injury resulting from high airway pressure
Compliance
The ratio of a change in volume to change in pressure. Most commonly used in reference to the lungs and chest wall.
Continuous Positive Airway Pressure (CPAP)
Airway pressure maintained above ambient.
Which factors affect delivered tidal volume?
1) Fresh gas flow
2) Leaks
3) Compliance and compression volumes
What is the difference between ascending and descending bellows?
Ascending bellows “ascend” during the expiratory phase, whereas the descending bellows “descend” during the expiratory phase.
What is scavenging?
Scavenging is the collection and the subsequent removal of waste anesthetic gases from the OR.
What is the NIOSH recommendation for maximum safe level of exposure of halogenated agents?
2 ppm
What are the two major causes of waste gas contamination in the OR?
1- The anesthetic technique employed.
2- Equipment issues.
What are the components of a scavenger system?
1- the gas-collecting assembly. 2- the transfer means 3- the scavenging interface 4- the gas-disposal assembly tubing 5- an active or passive gas-disposal assembly.
What is the most important component of the scavenger system?
the scavenging interface
What is an “open interface”?
An open interface has no valves and is open to atmosphere, allowing both positive and negative-pressure relief.
Should you use an open interface with a passive disposal system?
NO. Open interfaces should be used ONLY with active disposal systems that use a central evacuation system.
What is a “closed interface”?
Is a system that communicates with the atmosphere through valves.
How many types of closed interface systems are there?
- Positive pressure relief only
- Positive and negative pressure relief
What are the characteristics of the positive pressure relief only system?
1- A single positive-pressure relief valve designed to be used ONLY with passive disposal systems.
2- A reservoir bag is not required.
What are the characteristics of the positive and negative pressure relief system?
1- A positive-pressure relief valve, and at LEAST one negative-pressure relief valve.
2- It has a reservoir bag.
3- it is used with active disposal systems
What are the types of gas-disposal systems?
1- Active
2- Passive
Active gas-disposal system
- Most common.
- An interface with a negative pressure relief valve is MANDATORY.
- A reservoir is highly recommended
Passive gas-disposal system
- Doesn’t require the mechanical flow-induced device.
- Positive pressure relief is MANDATORY.
- Negative pressure relief and reservoir not needed.
Exhaust valve
A valve in a ventilator with a bellows that when open allows driving gas to exit the bellows housing.
Expiratory flow time
Time between the beginning and end of the expiratory flow.
Expiratory Pause Time
Time from the end of expiratory flow to the start of the inspiratory flow.
The time between the start of expiratory flow and the start of the inspiratory flow. It is the sum of the expiratory flow and expiratory pause times.
Expiratory Phase Time
What is a possible problem with piston ventilators?
Air entrainment with a disconnection. In this case, the machine will not alarm and the patient will continue to be ventilated, but air will be entrained, resulting in lower oxygen concentration and anesthetic agents.
What is the relationship between fresh gas flow, tidal and minute volume?
When the fresh gas flow is increased, the tidal and minute volume will increase. When the gas flow is decreased, tidal and minute volume will decrease as well
What is the ventilator driving gas?
Oxygen
What are the three types of alarms?
1- High priority (cannot be silenced)- immediate action
2- Intermediate priority- prompt action
3- Low priority- operator awareness but not necessarily action.
What will prevent barotrauma?
Setting the pressure 10 cm H20 above the peak pressure achieved with the desired tidal volume.
Trace gas levels in OR depends on…
1- fresh gas flow 2- the ventilation system 3-the length of time the anesthetic agents have been administered. 4- the measurement site 5- the anesthetic technique
What are some problems attributed to trace gas?
- Spontaneous abortions
- Infertility
- Birth defects
- Impaired performance
- Cancer
- Liver disease
Scavenging is…
the collection of excess gases from equipment used to administer anesthesia or exhaled by the patient and the removal of these gases to an appropriate place of discharge outside the work environment.
Dorsch CH 13.
What is the purpose of the gas-collecting assembly?
It collects excess gases and delivers them to the transfer means.
Conveys gas from the collecting assembly to the interface when the interface is not an integral part of the gas-collecting assembly
Transfer tubing
COPD, Asthma, emphysema
Pathologies that will benefit from prolonged expiratory time.
Monitor drive pressure and will alarm if pressure falls below 25 psig. It ensures that driving pressure is within a set safe parameter
Regulated Pressure Transducer
How often do you calibrate the oxygen sensor?
Every morning at 21%.
Every month at 100%
Y-piece
the most common site of disconnection
Tubing Sizes
Scavenger: 19 or 30mm
Common gas outlet: 15 mm
Breathing circuit: 22 mm
Protocol for mechanical ventilator failure
1- manually ventilate with the circle system.
2- bag with oxygen or room air
3- try to pass a suction catheter through the tracheal tube
4- visualize the hypopharynx and cords, or reintubate
What is the NIOSH recommendation for maximum safe level of exposure of halogenated agents with nitrous oxide?
0.5 ppm
What is the NIOSH recommendation for maximum safe level of exposure of nitrous oxide alone?
25 ppm
