Circuits and Flows Flashcards
what 3 factors influence uptake and distribution and therefore the anesthetic % delivered to the patient
1) vaporizer setting
2) anesthetic circuit
3) patient
what is oxygen consumption (VO2)
amount of oxygen required by cells to carry on normal aerobic metabolism
how do we ensure carbon dioxide production (VCO2) elimination
by ensuring FGF is high enough to remove CO2 with or without the soda lime absorber (depending on type of circuit)
you should use at least what FGF regardless of patient size… why?
1L/min… because precision vaporizers are less accurate in their output of anesthetic at flows of < 300-500 mL/min
what is the oxygen consumption for all species
5-10 ml/kg/min
oxygen consumption is within the (lower/higher) dose range for large animals and within the (lower/higher) dose range for small animals because of degree of __________
lower; higher; metabolism
in terms of CO2 removal, a rebreathing system can be (higher/lower/equal to) minute ventilation whereas a non-breathing system should be (higher/lower/equal to) minute ventilation
lower; equal
what is the equation for minute ventilation
VE = Vt x RR
what is tidal volume in most species
10-20 ml/kg/breath
do we more commonly use VIC or VOC
VOC: safer and more accurate
where is VIC located
between the inspiratory unidirectional valve and the patient
is anesthetic diluted more if the vaporizer is VIC or VOC
VOC
what is the effect of FGF on dilution of anesthetic for the following:
VIC
VOC
VIC: increased FGF = increased dilution (more slowly overcome)
VOC: Increased FGF = decreased dilution (more quickly overcome)
T/F both rebreathing and non-rebreathing systems can use co-axial tubing
T: for rebreathing would be an F circuit and for non-rebreathing is a Bain
how can you identify a bain system easily
it contains FGF tubing to connect to the common gas outlet of the anesthetic machine
what are the consequences of higher FGF in a non-rebreathing system (think of the properties of oxygen)
lower body temperature and less humidification
it is recommended to use a rebreathing system if patients are what size and non-rebreathing is patients are what size
rebreathing > 10kg
non-rebreathing < 10kg
what 3 things influence circuit dilution
1) size of circuit
2) FGF
3) vaporizer setting
why do we use higher FGF than VO2
1) to overcome dilution from the system and the patient
2) to reach dialed anesthetic % faster so that FA approaches FI faster
What are the FGF for a rebreathing system during the following:
- induction
- maintenance
- recovery
- induction: 100 ml/kg/min
- maintenance: 50 ml/kg/min
- recovery: 100 ml/kg/min (with iso off)
what are the FGF for large animals in the following:
- induction
- maintenance
- recovery
why are they different?
induction: 20 ml/kg/min
maintenance: 10 ml/kg/min
recovery: 20 ml/kg/min
flowmeters only reach 10L/min in anesthetic machines, so if we used the 100, 50, 100 metrics the flow would exceed that amount
with large animals it is mandatory to use
rebreathing system and fresh/active soda lime
what FGF do we use for a non-rebreathing system
200 ml/kg/min UNLESS the calculated amount is < 1L/min, in which case we use 1L/min
the FGF for a non-rebreathing system is about the same as what
minute ventilation (VE)
