MIDTERM REVIEW Flashcards
Types of Vaporizers: Variable Bypass Vaporizers
•Ohmeda Tec 4 & 5, Drager 19.1, 19.3
Types of Vaporizers: Blender
•Ohmeda Tec 6 (Desflurane)
Factors that influence Tec 6 Vaporizer Output
Varried Altitudes
Carrier Gas composition
Effects of Varied altitudes of Tec 6
Requires manual adjustments of the concentration dial with changes in barometric pressured
Increase in Barometric pressure results in
Decrease Vapor administered
Never fill the vaporizer with
Dial on the “On” Position
Overfilling can occur
if key not tightly on the bottom
If Tipping occurs:
3 things to do
• In hardened facilities turn in to maintenance
• Flush for 20-30 minutes with high FGF and set the
vaporizer concentration low
• End-tidal agent monitoring
Pumping effect is Associated with______ or ________
•
• Bypass has diluted vapor and vaporizing chamber is also saturated with vapor
• Causes higher than expected vapor concentrations
positive pressure ventilation or oxygen flushing
During Pumping effect, Oxygen flush is at __ psig-
•
transmitted back
Occurs during the inspiratory phase - PPV
During Pumping effect there is ______Flow through _________
• Reverse flow through the vaporizing chamber back into the bypass chamber
Pumping effect more pronounced with
- Low flow rates • Low dial settings • Low levels of agent in the chamber • Rapid respiratory rates • High peak inspired pressures • Rapid drops in pressure during expiration
Dalton’s Law of partial pressure
In a mixture of gasses the pressure exerted by each gas is the same as that which it would exert if it alone occupied the container.
Henry’s law
At a gas/liquid interface, some of the gas will dissolve
in the liquid.
Measure Flow characteristics (COMMON)
Carrier gas (CG) bubbles through agent Manual Temp. conversion Multi-agent Operator determines CG split No longer manufactured (but still present on field machines)
The Ohmeda Tec 6 vaporizer pressurizes the liquid and warms it at
39C.
Variable Bypass characteristics
CG flows over agent Auto adjust for Temp &Pressure Agent specific Auto CG split Higher safety standards
TEC 6 has______alarm
- Agent______
- Tilt
- Power Failure
- Internal malfunction
Low Agent
Illuminates with______
Warm-Up
No Output Alarm
< 20 ml (1 bar)
> 10 degrees
50cc of agent1
0 minutes to reach operating
temp of 39C
Low pressure system
Manifold/Flowmeters
➢Thorpe Tube, Needle Valves, Floats
❖Ohmeda – Link 25 Proportion Limiting Control
System
❖Narkomed - Oxygen Ratio Monitor Controller
(ORMC)
❖Vaporizer Mounting Devices & Vaporizers
❖Common (fresh) Gas Outlet
❖Outlet Check Valve (only on Ohmeda)
❖Pressure Relief Device
HIGH PRESSURE SYSTEM
Size E Cylinders on back of machine ❖Cylinder pressure gauge (Bourdon) ❖Check valves in the hanger yoke ❖Index pins on the hanger yoke ❖Pressure regulator, i.e. First stage regulator
Intermediate pressure system
Pipeline inlet connections ❖DISS (diameter index safety system) ❖Pipeline check valves ❖Pressure gauges from pipeline ❖Machine piping (usually metal) ❖Gas power outlet for ventilator (outside the bellows) ❖Master Switch Oxygen Pressure Sensor “failsafe” Shut Off Valve (Ohmeda) ❖Oxygen Failure Protection Device “failsafe” (Narkomed) ❖Oxygen Supply Failure Alarm ❖Oxygen Flush valve ❖Second stage regulator ❖Before (Upstream) - Flow control valve (Sits on the fence)
Five main pathways or functions
- Powers the ventilator
- Oxygen flush valve
- Oxygen supply failure alarm
- Opens the pressure sensor shutoff valve
- Second stage pressure regulator
▪ Bypasses flowmeters etc & goes straight to
Common Gas Outlet
O2 flush valve
Flush valve flow rate _____LPM and presssure of _____
35-75 LPM at 50 psig
If O2 pressure drops below 20 psi, flow of
N20, Air, Helium are stopped by PRESSURE SENSOR SHUT OFF VALVE
2nd stage regulator reduces O2 pressure to
▪ Reduces Nitrous Oxide to
14 -16 psi
26 psi
Valve that is part of the 2nd stage regulator
Diaphragm
Oxygen SUPPLY FAILURE Alarm is activated when PSI falls below:
▪ Ohmeda:
▪ Narkomed:
28 psi
30-37 psi
Oxygen powers vent at ___-psi
50
Main component of CO2 absorber is
Calcium Hydroxide (80%) Na Hydroxide (4%) KOH 1%
100 gm of soda lime will absorb
approximately 26 L of CO
DO NOT change CO2 absorber midcase just
increase fresh gas flow to 5 L/min
CO2 absorber granules sizes
4-8 mesh
Purpose of varying Granule size
▪
Smaller granules increase surface area
▪ Smaller granules decrease channeling
▪ Larger granules decrease resistance
Opening/loosening the knob of APL________ the flow to the scavenging system -____pressure
increases; decrease
➢ Tightening/closing the knob will
Increase ability to give positive pressure ventilation
PISS position Air Oxygen N2O Nitrogen
1-5
2-5
3-5
1-4
Oxygen tank is at _____psig and
1900
Oxygen tank volume is
660L
AIr tank volume is
625L
Air tank pressure is
1900
N2O tank volume is
1590
PSI of N2O tank
745
Oxygen H tank volume
6900L
Oxygen H tank pressure
1900
What gas law governs tank pressures?
Boyle’s Law
P1V1 = P2V2
Formula
Actual gauge reading (psi) / (Initial filling pressure X (known liters full) / (total liter flow))(psi)
Formula with constant
PSI X constant / L/m = minutes before left empty
Constant for E cylinder
0.30
NIOSH for N2O
< 25 ppm
NIOSH exposure limit for Halogenated Agents
< 2 ppm
NIOSH Halogenated Agents and N2O
< 0.5 ppm
Macroshock -
gross amounts of shock that will
cause harm or death
- Microshock -
amount of shock that will harm or kill a patient with a conduit to the heart
Disruption of electrical function of cells
a. contraction of muscles
b. alteration of brain function
c. paralysis of respiration
d. ventricular fibrillation
1st stage and 2nd stage regulator
Diaphragm
Free floating valve
Check valve
Ball and spring
Ventilator Power Outlet Valve
Oxygen Flush Valve
Pin & Spring/Diaphragm
Pressure Sensor Shut Off Valve
Flow Control Valve
Needle valve
Adjustable Pressure Limiting (APL)
Spring/Diaphragm
What is MAC?
Alveolar concentration that prevent MOVEMENT in 50% or patients in response to a standardized stimulus
MAC mirrors
Brian partial pressure
Speed induction
ELLI- DHH
- Elimination of rebreathing
- Low anesthetic-circuit volume
- Low absorption by the anesthetic circuit
- Increased ventilation.
- Decreased solubility
- High fresh gas flows
- High cerebral blood flow (CBF)
Volatile agents all blunt the
Ventilatory stimulation evoked by arterial hypoxemia
Vessel rich group
75%
Nitrous oxide causes on MAP
Unchanged
mildly increases
HR increase minimally with
Desflurane
Only FDA approved for induction
Sevoflurane
VP pressure of isoflurane
160
VP pressure of Desflurane
664
VP pressure of Sevoflurane
239
Blood Gas partition coefficient of isoflurane
1.4
Blood Gas partition coefficient of Desflurane
0.45
Blood Gas partition coefficient of NITROUS OXIDE
0.47
The impact of tissue.
- the duration of anesthesia
2. Solubility of the anesthesia in various tissue compartments
BLOOD gas partition coefficient of Sevoflurane
0.65
The low solubility of________ in blood and body tissues causes a very rapid induction of and emergence from anesthesia.
desflurane
Prolonged exposure to anesthetic concentrations of nitrous oxide can result in
bone marrow depression (megaloblastic anemia) and even neurological deficiencies (peripheral neuropathies).
Halothane lowers
MAP by decreasing CO , SVR unchanged
Greatest change in SVR by those agents
Iso and Des (decrease SVR)
Rapid increases in_________ concentration lead to transient but sometimes worrisome_________that are more pronounced than occur with isoflurane, particularly in patients with cardiovascular disease.
desflurane elevations in heart rate, blood pressure, and catecholamine levels
2.0 MAC of halothane in patients not undergoing surgery results in a
50% decrease in blood pressure and cardiac output
