Anaesthesia Flashcards
Factors affecting choice of breathing system (6)
resistance
rebreathing
fresh gas flow requirements
mechanical dead space
circuit drag
cleaning and maintenance
Circle
- rebreathing
- soda lime
- low fresh gas flow requirement - 10ml/kg/minute
- higher flow at start to avoid alveolar hypoxia from dissolved nitrogen in blood
- economical use
- expensive to buy
- increased resistance
- unidirectional valves prevent mixing - need maintenance
Magill
flow = 1*minute volume
can’t be used for IPPV
Lack
flow = 1*minute volume
either tube inside tube or parallel
can’t be used for IPPV
Mini Lack
flow = 1*minute volume
<10kg
parallel tubes
can’t be used for IPPV
T-Piece
flow = 2-3*minute volume
long tube, t connector, short tube with bag
<8kg
can use for IPPV
Bain
flow = 2-3*minute volume
co-axial tube
7-10kg
Can’t use for IPPV
Humphrey ADE
Lever up - lack
Lever down - t-piece
Circle
Can use for IPPV
Monitoring - temperature
hypothermia
rectal thermometer or oesophageal thermoprobe
core-periphery difference - early CV problem sign
low temperature –> increased pain, increased infection, delayed recovery
Causes of temperature fall (7)
Vasodilation
reduced shivering
reset thermoneutral point
open body cavity
cold gases
dry gases
wetting and prep
Monitoring - Pulse
Femoral
dorsal metatarsal (disappears with hypotension)
lingual
auricular
Monitoring - Pulse Oximetry
% oxygen saturation of hemoglobin
accuracy affected by - circulation, ambient light, movement of probe, pigmented skin
probe design not always suitable
Monitoring - ECG
to detect arrythmia
Monitoring - Capnography
CO2 breathed out
info on cardiac and respiratory function
info about - rebreathing, cardiac oscillations, ETT obstruction
increase ETCO2 - hypoventilation
decreased ETCO2 - hyperventilation
sudden drop - cardiac arrest
Monitoring - Blood Pressure
used with HR to determine cardiac output
non- invasive - sphygomanometry, oscillometric, doppler
invasive - cannula for direct BP measurement
Decreased blood pressure causes - anaesthesia (4)
IV fluid loss (hemorrhage)
failing myocardial function
sepsis
relative hypovolemia - vasodilation (sepsis, drugs)
Monitoring - CNS
eye position
jaw tone
EEG - electrical output from brain (bispectral index from 100 (awake) - 60 (general anaesthesia) - 0 (flat line/dead))
Common problems - recovery
Prolonged recovery - hypothermia, too much pre-med, too deep during maintenance, hypoglycemia, choice of inhalant, choice of induction agent
Airway obstruction - debris or gauze, body fluids
Agitated recovery - inadequate pre med or analgesia
BOAS patients
sedate for recovery
supplementary oxygen
leave in IV
leave in ETT until sat up
retube if - cyanosis, distress, low SPO2, paradoxical breathing
ETT
Red rubber - opaque, high pressure seal so can irritate, crack easy
PVC/silicon - less prone to kinking, non-irritant, less pressure, transparent
Armored - coil of wire through - kink resistant, need stylet to place, can be damaged if bite down, can’t reduce dead space
Cole Patter - human pediatric - exoticss
cats - lidocaine sprat
cuff with pilot balloon
Supraglottic airway devices
sit above larynx and envelopes
cats and rabbits - v-gels
Complications - ETT (5)
high pressure/low volume - tracheitis or pressure necrosis
disconnect when moved
leaks
over insertion
improper cleaning - infection, irritation
IV placement
cephalic
saphenous - brachycephalics
jugular - right side, sampling
auricular - peripheral - rabbits and floppy ear dogs
Complications - IV placement (5)
extravasation
thrombosis
thrombophlebitis
emboli
exsanguination
Anaesthetic Machine Components (7)
pressure regulator - maintains constant gas flow
flow meter - tells oxygen level
vaporiser - contains anaesthetic agnt
check valve - stop backflow to vaporiser
back bar - contains pressure relief valve
common gas outlet
Gas Colours
Tanks -
Oxygen - black with white top or just white
Nitrous oxide - blue
Wall sockets -
Oxygen - green
Nitrous - blue
Medical air - yellow
Alternatives to oxygen tanks
cryotanks
oxygen generators
Anaesthetic machine checks (5)
visual check
leak check - check alarms are working
bain - occlude end with syringe, pressure should drop
breath into circuit to check valve
soda lime colour
Anesthetic machine safety features (6)
oxygen failure alarm
oxygen failure protection device
hypoxic mixture alarms
interlocks between vaporisers - one volatile agent at once
pin safety index system on gas cylinders
gas hoses with non-interchangeable valve connectors
