Patient monitors and defibrillators Flashcards
What accounts for a dual-plateau (low at first then a high tail at the end) capnogram?
a leak in the gas sampling line
What accounts for a double-peak (high peak at first then a slow rise to a second peak) capnogram?
single lung transplant: first peak is the healthy lung, second peak is the diseased, obstructive lung
What can cause a slurred downslope in the capnogram?
inspiratory valve OR expiratory valve stuck open (both cause increased inspired CO2)
How is CO2 most commonly detected in the OR?
IR absorption (also used for nitrous oxide and inhaled anesthetics)
What technology can be used to measure levels of ALL gases used in the OR?
Raman scattering
What are the 3 ways oxygen can be measured?
paramagnetic (switching magnetic fields), polarographic (oxidation-reduction), and galvanic (battery)
Which muscle relaxants will give you fade on train-of-four stimulation? Why?
Non-depolarizing, because they inhibit positive feedback of ACh via presynaptic nAChRs.
In what situation is tetanic stimulation useful?
When you have 0 twitches on train-of-four stimulus, post-tetanic twitch count can help you estimate how much time you have left until twitches return on TOF stimulus.
In what way is double-burst stimulation superior to TOF?
Manual detection of fade is much more accurate with double-burst stimulation.
Is pulse pressure wider or narrower at the radial artery compared to the aorta?
wider
What is the sensitivity of monitoring leads II and V5 in detection myocardial ischemia?
80%
What do the waves (a, c, x-descent, v, y-descent) on a CVP tracing represent.
a: atrial contraction
c: ventricular contraction
x-descent: ventricular emptying
v: venous return to the atrium
y-descent: atrial emptying
What scenarios give you Cannon A waves?
A-V disociation: periodic Cannon A waves
tricuspid stenosis: continuous Cannon A waves
What scenarios give you tall A and V waves?
RV ischemia and pericarditis
What is the equation for PVR? Normal value?
80 (PAP-PCWP) / CO
100-200
What are indicators of ischemia with a PA catheter?
increase in average pressure
tall V waves as you develop functional MR
What is the Law of LaPlace?
T = P x r / 2L
T-wall tension
P-cavity pressure
r-cavity radius
L-wall thickness
How is oxygen content in the blood calculated?
CaO2 = 1.34 (Hgb x SaO2) + PaO2 (0.003)
What is the estimated incidence of CLABSI?
5%
What are the relative colonization rates of arterial vs. central venous catheters?
same, although central venous catheteres are more often implicated in blood stream infections
What mechanism accounts for most perioperative heat loss?
radiation
What is the maximum reduction in CMRO2 achievable with sodium thiopental?
50%
What is seen on EEG with high doses of opiates?
high amplitude delta waves
Is biphasic or monophasic defibrillation more effective? Which uses more energy?
Biphasic is more effective.
Monophasic uses more energy.
Is defibrillation more effective during inspiration or expiration? Why?
expiration, because air impedes energy transfer
What is the proper name of the polarographic electrode used to measure the partial pressure of oxygen in a blood sample?
Clark electrode
What TOF ratio correlates with a 5-second head lift? Ability to oppose incisors against a tongue depressor?
- 6 for head lift
0. 85 for bite
What device is used to measure pH?
Sanz electrode
What device is used to measure pCO2 in a blood sample?
Severinghaus electrode
