8. Monitoring Anesthesia Flashcards
The big 5s
ECG, pulsox, capnograph, BP, temperature
main causes of complications of anesthetic death
respiratory and CV
50% in post-op period
which palpebral do you loose first?
lateral
Guedel’s classification
clinical assessment of CNS, eyes mostly, old school
BIS bispectral index
0-100 100 = awake
indicates level of consciousness
results controversial in dogs, used in humans
why monitor BP?
indicates tissue perfusion
hypotension
MAP <65mmHg
range of pressure where range of perfusion to organ is preserved, below 65 autoregulation is not preserved and adequate perfusion will not happen
measuring BP
Indirect v. Direct
*pulse does not indicate BP its just difference between systolic and diastolic
Oscillometic method
indirect, cuff inflates above systolic and deflates in stepwise fashion, when the P = systolic the vessell starts vibrating, when vibrating the most thats the MAP.
cuff width
40-60% circumference of extremity, between ELBOW AND CARPUS is best!
inaccurate BP because?
wrong size cuff!! (too big cuff -> lower BP, vice versa) And put cuff at level of the heart
Doppler method
emits US, signal becomes sound indicating blood flow. First audible sound = systolic AP.
- does NOT give diastolic or mean!!!!!!!
- **sortof inaccurate, portela doesn’t like it.
Direct monitoring
gold standard. continuous monitoring*
which artery for direct BP?
dorsopedal artery (dorsal metatarsal) most often (lingual, radial/carpal, coccygeal, femoral, auricular) *Flush regularly to avoid clotting
inaccuracies of direct bp monitoring?
- overdamping - air bubble, systolic lower than real
2. underdamping - systolic higher than real number
Fluid responsiveness
increase in volume causes inc. left ventricle, inc. preload, inc. stroke volume.
- doesn’t work if in FLUID OVERLOAD
Pulse pressure variation must be ____ for patient to be responsive to fluids
above 15%
what measures Tidal volume
wright respirometer
What is capnography
indirectly measures ventilation, espimates PaCO2
- differences between PaCO2 and end tidal CO2 due to dead space ventilation
- can indicate, problem in circuit, obstruction, cardiogenic shock
What happens when hypoventilating?
- if hypoventilating, theyre moving mostly deadspace, end tidal CO2 would be low
- if ET CO2 is low, give a big breath and see if it goes up (if it doesn’t they may be hyperventilating)
two types of capnography monitoring
- side stream:
- monitor is away from patient, sampling continuously, delayed response every time it aspirates
- in small animals doesn’t work
- sample is contaminated in nonrebreathing system - main stream:
- monitor in connector, in real time, more accurate, big awkward thing connected to tube
low ET CO2 indicates?
high ET CO2 indicates?
hyperventilation/deadspace
hypoventilation
Ventilating Deadspace indicates what on capnography??
Low end tidal CO2
** Know this, he kept saying it**
Check by giving big breath!!
Cardiac oscillations
normal, heart pushing on lung parynchyma
/| alpha angle increased?
obstruction! kink in ET, bronchoconstriction
|\ shark fin? (swimming towards you)
Leak, or washing out with high flow O2
inspiration doesn’t go down to 0 on capnograph?
increased baseline
rebreathing CO2
exhausted exorbant, or unidirectional valves not working.
gradual decrease in ET CO2
sudden bp drop, or CO drop, cardiac arrest, PTE
Sudden disappearance of capnograph waveform?
apnea, disconnection
90 Hb saturation indicates ____ PaO2
60 mmHg
uses absorbance of infared light for O2 saturation?
- affected by?
pulsox
- ambient light, motion, skin pigment
vasoconstriction during anesthesia affects temperature mostly during the _______. Loose heat via skin
first hour.
Preheat if you predict your animal will get hypothermic
(skinny, small dogs)
hypothermia causes
marked CNS depression, little or no anesthetic req, unresponsive bradycardia
