Where does the breathing circuit begin?
Fresh gas outlet
Most common portable tank? Pressure and volume?
2,000 psi, 700L
Most common bulk tank? Pressure and volume?
2,000 psi, 7,000L
Name the cylinder color for:
4) medical-grade air
Which safety system prevents hooking up a PORTABLE tank to the incorrect yoke?
Pin index safety system
each type of gas tank has holes in unique locations that align with pins on the corresponding gas line
Working pressure entering into the anesthesia machine?
2 mechanisms that can be present on WALL OUTLETS to prevent hooking up supply lines to the wrong source?
Diameter Index Safety System
How does activation of the oxygen flush valve affect anesthetic concentrations in the system?
Decreases (dilutes) them
Which part of the anesthesia machine enables the liquid anesthetic to become a vapor and mix with oxygen?
Common outflow for the vaporizer and oxygen flush?
fresh gas outlet
this is also where the breathing circuit connects
4 classifications of breathing circuits?
2) semi-open (non-rebreathing)
3) semi-closed (circle)
4) closed (circle)
4 advantages of non-rebreathing over circle system
1) low resistance
2) simple (low failure)
3) no distance limitations
4) immediate control of inspired concentration
Main difference between semi-closed and closed circuit?
in semi-closed, FGF exceeds patient’s metabolic requirement
Closed only supplies enough to meet patient’s metabolic needs
Purpose of Sodasorb and what are the by-products of its interaction with CO2?
Sodasorb scavenges CO2 from expired gas
produces water and heat
2 purposes of APL (pop-off) valve?
1) vents excess gas from circuit
2) close to provide patient with manual ventilation
This structure of an ET tube provides a secondary airway should the primary lumen become occluded
T/F: The cuff on an ET tube will eliminate the risk of aspiration entirely
*cuff mainly serves to reduce leaks for positive pressure ventilation
Name two advantages of ISO over SEVO
Iso is more potent and costs less
COST= PRIMARY advantage
Name one advantage of SEVO over ISO
It’s less soluble (works faster)
Less soluble= good; less will go to blood and other tissues…more to brain!
Both SEVO & ISO are administered as _____
Vapor pressure denotes the ability of a substance to ______
higher vapor pressure=more likely to evaporate
In a mixture of gases, the pressure exerted by one gas if it occupied the space alone?
How to calculate partial pressure?
multiple the % of the gas of interest by the atmospheric pressure
Clinically useful way to record the amount of inhalant being administered to a patient?
Blood: gas PC determines?
induction and recovery
*lower PC= less soluble (less molecules in blood)= faster induction & recovery
Oil:gas PC determines?
cannot determine induction speed using this
Time constant = ?
Volume(L)/ flow (L/min)
time it takes to fill a container
% of changes after:
1 time constant?
4 time constants?
after 1: 63% changed
after 4: 98% changed
Rank order of distribution of inhalants to the 4 different tissue groups (most saturated to least)
vessel rich (brain & viscera)
vessel poor (cartilage, bone)
Name 2 factors that influence alveolar concentration?
1) concentration of inhaled anesthetic
2) alveolar ventilation (depth of breath)
What measurable variable reflects the partial pressure of an inhalant present in the brain?
expired volume percent
3 disadvantages of an oxygen concentrator?
1) requires electricity to work
2) doesn’t deliver pure oxygen
3) doesn’t use pressurized gas (can’t use ventilator)
The flowmeter is measured in ______ and it’s normal range is ?
4 purposes of the breathing circuit
1) deliver gas mixture to patient
2) remove CO2 from patient
3) secure airway
4) provide ventilation
4 disadvantages of non-rebreathing compared to circle system
1) high FGF rate ($$)
2) loss of heat and moisture
3) environmental pollution
4) harder to control manual ventilation if needed
Two purposes of reservoir bag?
1) provides excess capacity to build between breaths
2) used for manual ventilation
4 advantages of circle system over non-rebreathing
1) lower FGF (cheaper)
2) preserves heat and moisture
3) less pollution
4) easier to provide mechanical ventilation
4 disadvantages of circle vs. nonrebreathing
1) higher resistance
2) complex (higher failure rate)
3) constrained distance
4) takes time to equilibrate circuit to new concentration
3 advantages and disadvantages of closed over semi-closed
1) conserves gas
2) preserves heat and moisture
3) no pollution
1) longer equilibration (hrs)
2) accuracy of vaporizer
3) tricky monitoring
Disadvantages of inhalant anesthetics (3)
narrow therapeutic index
expensive initial investment
doesn’t block nociceptive input
3 factors that affect arterial concentration of inhaled anesthetics
1) blood:gas partition coefficient
2) cardiac output (CO) (higher=slower induction)
3) arterial-venous concentration difference (larger difference drives things to arterial side & we don’t want that… so larger difference=slower induction)