Hemodynamics Flashcards
What is the AANA standard for monitoring and alarms?
Standard 9: when monitoring device used, variable pitch and threshold alarms are set and audible, vitals q5 min, cont. pulse ox, etCO2, cont HR monitor, twitch monitor - paralytics, use temperature monitoring and regulation bc pt at risk for MH d/t exposure to anesthetic gas
First duty as CRNA
vigilance
Describe Precordial/Esophageal Stethoscope, whats it used for, wheres it placed?
continuous monitoring of heart and breath sounds and minimally invasive. use to assess for windmill murmur (VAE) or bronchospasm (peds). Precordial on chest. Esophageal 28-30 cm into esophagus.
Normal PRI
0.12-0.2s
Normal QRS
0.08 - 0.1s
Normal QT
0.4-0.43
Normal RR
0.6-1s
What can ECGs detect? (5)
arrhythmias, HR (based on R-R wave), ischemia, electrolyte changes, monitor pacemaker function
What view is missing in a 3 lead EKG?
anterior view
What are the limitations (4) of a 3 lead EKG and what is needed to be able to detect them?
ST monitoring, BBBs, VT, SVT - need a true V1 lead to detect arrhythmias
Majority of dysrhythmias and ischemia can be detected via what two leads?
II and V5
Gain should be set at what?
standardization, 1 mV produces 10 mm pulse, able to monitor 1 mm ST change
What should filtering capacity be set to, and why?
diagnostic mode, filtering out low end can distort ST segment
If monitoring ST segment, what should be done before pt is anesthetized?
get baseline ST segment
What are 6 indicators of ischemia?
st elevation > 1mm, T wave flat/inverted, q wave, st depression/flat/downslope > 1mm, peaked t wave, arrhythmias
Most common ST change and why?
ST depression, indication of demand problem bc heart stressed decreased HR, increased O2 demand
ST elevation is an indication of what?
blockage
What are some common causes of ST changes other than ischemia (4)?
drugs (digitalis), temp changes (hypo - depression), hyperventilation (elevation), position changes (elevation)
The leads that monitor ST changes in the inferior, lateral, anterior, and septal walls including the artery are:
Inferior: II, III, AVF - RCA
Lateral: I, AVL, V5, V6 - CxA (LCA)
Septal: V1, V2 - LCA
Anterior: V3, V4 - LCA
Exercise-related ischemia is most sensitively detected in what leads?
V4 V5
When is peak SBP generated?
ventricular contraction
Changes in SBP correlate with what?
changes in myocardial O2 requirements
DBP is a trough pressure and is generated during
ventricular relaxation
Changes in DBP indicate what?
coronary perfusion pressure
How to calculate pulse pressure?
SBP - DBP
What is MAP?
weighted average of arterial pressure during pulse cycle
How is MAP calculated?
SBP + 2/3DBP
Intraoperative hypotension is defined as (and its exception)?
MAP < 55-60 mmHg (HTN pts may need higher MAPs due to a shift in their autoregulatory curve)
List types of BP measurement (5) and describe
palpation - palpate return of pulse when cuff deflated only measure SBP (underestimates),
doppler - underestimates SBP, sound waves
auscultation - steth/cuff/sphygmomanometer uses kortkoff sounds, estimates SBP and DBP (unreliable HTN)
oscillometry - automatic cuff, measures SBP/DBP/MAP
continuous NIBP finger - unreliable
Gold standard for BP measurement?
arterial line
What SBP do peripheral and central pulse become weak?
peripheral <90, central < 70
Which measurement is most reliable: SBP or DBP or MAP?
MAP
What is the ideal circumference and ideal length for a NIBP cuff?
40% circumference, 80% circumference
What happens when too small of a cuff is used?
false high readings
What can cause false high BP readings? (6)
cuff too small, cuff too loose, extremity BELOW level of heart, arterial stiffness (HTN, PVD), dysrhythmias, tremors/shivering
Why does arterial stiffness cause artificially high BP?
d/t widening pulse pressure and discrepancy between UE and LE
What can cause falsely low BP? (6)
cuff too large, extremity above level of heart, poor tissue perf., quick deflation, dysrhythmias, tremors/shivering
Complications of NIBP measurement? (6)
pain, petechiae/ecchymoses, limb edema, venous stasis/thrombophlebitis, peripheral neuropathy, compartment syndrome
What type of patients are vulnerable to complications of NIBP? (5)
peripheral neuropathies, arterial/venous insufficiency, coagulopathies, recent thrombolytic therapy, post-mastectomy
How is an arterial BP waveform formed?
ejection of blood from left vent. into aorta during systole then peripheral run off during diastole
Indications of arterial cannulation? (5)
cont. real time BP, planned pharmcological/mechanical cardio manip., repeated blood sampling, failure of indirect BP measurement, diagnostic info needed from waveform (valve changes)
Extreme dorsiflexion of a wrist where an arterial line is located can cause what complication?
median nerve damage
What arterial cannulation site is preferred in peds?
pedal
Complications from arterial line are more likely when (7)? And what is the relative risk over all of arterial line insertion?
arterial spasm, previous arterial injury, thrombocytosis, protracted shock, high dose vaso pressor admin., prolonged cannulation, infection
low risk overall
Allen test tests for what? What is its predictive value?
To see if pt can tolerate arterial line in that extremity.
Predictive value is low.
How is allen test done?
Compress both radial/ulnar art., pt makes tight fist, pt then opens hands (no hyperextension), release ulnar occlusion, normal color returns w/ in seconds. > 6-10 seconds means reduced flow
Indications for Arterial Lines? (8)
deliberate hypotension, wide swings in intraop BP, r/o rapid changes in BP, rapid fluid shifts, vasoactive drugs, end organ disease, repeated blood sampling, failure of BP measurement
How to make arterial lines more accurate? (6)
minimize tube length, limit stop cocks, no air bubbles, mass of fluid small, using stiff tubing, calibrated at level of heart (phlebostatic axis) or at meatus/circle of Willis if concerned at cerebral perfusion
What is the rate of passive flushing in an arterial line?
1-3 mL
The dicrotic notch represents what mechanical event?
aortic valve closure
Which comes first, mechanical event or electrical event?
Electrical, then mechanical
The distance from the systolic peak of an arterial line from the dicrotic notch moves _____ the more distal the insertion site is.
increases
Describe the parts of an arterial waveform.
aortic valve opens, slope of systolic upstroke represents contractility, peak of systolic upstroke is SBP/isovolumetric contraction of ventricles, area under curve from peak to dicrotic notch is SV (EDV-ESV) and represents myocardial O2 demand
dicrotic notch is where aortic valve closes, pressure drops as blood flows out of aorta, from dicrotic notch to lowest pressure represents myocardial O2 supply, DBP is the lowest point of the waveform, pulse pressure is the difference from the peak to lowest pressure.
Describe underdamped arterial line and what causes are (4)?
systolic pressure overshoot; caused by catheter whip or artifact, stiff noncompliant tubing, tachycardia/dysrhythmias
Describe overdamped arterial line and what causes are (6)?
diminished pulse pressure; loose connections, air bubbles, kinks, blood clots, arterial spasms, narrow tubing
What interventions can you try for damped waveforms? (5)
pressure bag inflated 300 mm Hg, reposition extremity/pt, verify appropriate scale, flush/aspirate line, check/replace module/cable
The square wave test ensures what?
arterial line is optimally damped (only two oscillations after a flush)
What is the phlebostatic axis?
a reference point for zeroing arterial line, 4th intercostal space, midaxillary line
What pressure are all physiological pressures referenced to in invasive lines?
atmospheric pressure
A 20 cm difference in height produces a ___ mmHG difference in pressure.
15, aka for every 1cm its 0.75 mmHg difference
Examples of arterial line complications are (10)
nerve damage, hematoma/hemorrhage, infection, thrombosis, air embolus, skin necrosis, loss of digits, vasospasm, arterial aneurysm, retained guide wire
How does \_\_\_\_ affect arterial waveform? a aortic stenosis b aortic regurg c hypertrophic cardiomyopathy d systolic LV failure e cardiac tamponade
a pulsus parvus (narrow pp), pulsus tardus (delayed upstroke) - weak pulse
b bisferiens pulse (double peak), wide pulse pressure
c spike and dome, mid systolic obstruction
d pulsus alternans (alt. pp amplitude) alternating strong and weak beats
e pulsus paradoxus - drop in SBP during spont. resp.
What does pulse pressure variation (PPV) measure and thresholds?
measures pt’s responsiveness to fluid bolus
> 13% fluid responsive, dehydrated
<9% fluid overloaded
Whats a way to observe fluid responsiveness via SpO2 pleth?
If SpO2 goes down with positive pressure it is bc of increase in intrathoracic pressure, ie overloaded
What are the requirements to be able to measure PPV? (4)
NSR, intub/mech vent., vent w/ 8 mL/kg of Tv, no sig. alterations to chest compliance (like open chest)
Describe how to measure PPV.
1.) condense waveform from 25 to 6.25 mm/sec. 2.) find pulse pressure during inspiration and during expiration 3.) enter into formula: (PPmax-PPmin)/mean of the two X 100
What law allows SpO2 to be measured via pulse ox, also describe it?
Beer Lambert Law; concentration of dissolved substance is directly proportional to absorbance of light
What wavelengths are absorbed in a pulse ox?
660 nm - deO2Hb
940 nm - O2Hb
What causes inaccuracy in pulse ox? (6)
dyes, malposition, dark nail polish, different Hb (metHb, carboxy Hb), electrical interference, shivering
What is the oxyhemoglobin curve?
Describes the nonlinear relationship between SaO2 y-axis (O2 saturated Hb) and PaO2 x-axis (pp of arterial O2). The curve flattens out at 60 mm Hg indicating little change in O2 saturation past this point. Below 60 mmHg the curve is steep indicating small change result in large drop in O2 saturation. Describes O2’s affinity for Hb. Shift toward left increases O2’s affinity for Hb causes hypoxia bc no O2 to cells/tissues, O2 goes back to lungs w/out being used. Shift right decreases O2’s affinity for Hb means more O2 to tissues/cells, but also less O2 picked up from lungs in first place.
What causes a LEFT shift on the O2Hb curve?
What causes a RIGHT shift?
LEFT: alkalosis, hypocarbia, hypothermia, decreased DPG, COHb, fetal Hb
RIGHT: acidosis, hypercarbia, hyperthermia, increased DPG
How does carboxyHb affect SpO2?
Falsely elevates SaO2
How does metHb affect SpO2?
Falsely lowers SaO2
Indications for CVC? (8)
CVP, admin drugs (vasoactives), temp HD, transvenous pacing, PAC and monitoring, rapid fluid infusion, aspiration of air emboli, inadequate peripheral access, blood sampling
Insertion sites and complications of each
RIJ - preferred, high accuracy, direct to SVC; LIJ r/o pneumo d/t cupola of pleura higher on left, r/o of carotid cannulation d/t anatomy; subclavian - pneumo and arteial puncture, EJ, femoral
Where should a CVC tip be placed?
Just above junction of SVC and RA, T4-5, carina, above 3rd rib
What are the measurements of a CVC?
7 fr, 20 cm length
CVC contraindications? (4)
R atrial tumor, contralateral pneumo, infection at site, thrombus in intended insertion vein
Complications of CVC insertions (9)
vascular injury - cardiac tamponade, aw compression from hematoma, pneumo, nerve injury, arrhythmias, thrombus/embolus, infection, misuse of equipment, misinterpreting data
Normal CVP, and what it rises to when mech vent?
2-7 mmHg, rises by 3-5 mmHg
CVP is also know as
RAP or RV preload
Describe cvp waveform and associated mech events in EKG waveform.
a - atrial kick, atrial contraction, end diastole (PQ)
c - isovolumetric contraction (no volume change), tricuspid closed and bulges back into RA, early systole (RS)
x - mid systole, RA relax. (T)
v - systolic filling of RA, ventricular ejection, tricuspid closed, late systole (T)
y - early diastole, tricuspid open early ventricular filling (T)
Describe cardiac cycle.
0.8 s 1) venous blood return to RA via SVC/IVC, 2) isovolumetric relaxation, all valves closed, 3) passive ventrical filling tricuspid & mitral valves open/atrial & pulmonic valves closed, 70-80% blood, blood flows from atria to ventricles, 3) active ventricular filling, atrial contraction/kick, 20-30% blood, 4) isovolumetric contraction, valves closed 5) ventricular contraction, tricuspid/mitral valves closed, aortic/pulmonic valves open, systole
What is the most prominent wave on CVP and whats it represent?
a wave, atrial kick/contraction, P wave, end diastole
Describe CVP waveform abnorm.
afib - loss of a, prom c
av diss. - cannon a
tricuspid regurg - tall c-v wave, no x
tricuspid stenosis - tall a, atten y
RV ischemia - tall a v , steep x y, mw config
pericard constrict - tall a v , steep x y, mw config
card. tamp. - dom x, atten y
What does a PAC do? (7)
intracardiac press., estim. LV filling press., indirectly assess LV, CO, mixed venous O2 sat., PVR/SVR, pacing
Blue port on PAC is ____
Yellow port on PAC is ____
proximal,
distal
PAC stats
7 fr, introducer 8.5fr, 110 cm length (10 cm int), 4 lumens (distal - PAP, second -30 cm prox cvp, 3rd - balloon, fourth - thermistor
Indications for PAC (8)
LV dysfunction, valve disease, pulm htn, cad, ards/resp fail., shock/sepsis, arf, surgical procedure
PAC complications (9) relative contraindications (2)
arrhythmias, RBB, cath knotting, balloon rupture, thrombus/air embolus, pneumo, pa rupture, infection, dmg to cardiac structures
WPW, LBBB
PAC distances from RIJ to:
a) VC, RA junction
b) RA
c) RV
d) PA
e) wedged
a) 15 cm
b) 15-25 cm
c) 25-35 cm
d) 35-45 cm
e) 40-50 cm
Describe PCWP Waveform w/ pressures
RA - acxvy wave (CVP), 2-6 mmHg;
RV - large camel humps, 15-30 mmHg sys, 2-8 mmHg diast;
PA - dicrotic notch returns, 15-30 mmHg sys, 5-15 mmHg diast;
wedge - av waves, small camel humps, 6-12 mmHg
Normals:
a) SVR
b) PVR
c) CO
d) EF
e) CI
f) EDV
g) SV
h) PIP
i) Tv
j) etCO2
a) 50-100 mL/beat
b) <250 dynes - sec/cm3
c) 4-8 L/min
d) 55-70%
e) 2.4-4 L/min/m3
f) 65-230 mL
g) 50-100 mL/beat
h) 15-20 cmH2O
i) 6-8 mL/kg ideal body wt.
j) 35-40 mmHg
What are the 5 types of CO monitoring?
thermodilution, cont. thermodilution, mixed venous oximetry, ultrasound, pulse contour
TEE for 7:
ventr. wall characteristics/motion, valve structure and func., EF, CO, blood flow, intracardiac air, intracardiac masses
Uses of TEE (8)
unusual hypotension/acute, pericard. tamponade, PE, aortic dissec., myocard ischemia, valve dysfunc.- AL changes, wall motion
Complications of TEE (4)
esophageal trauma, dysrhythmias, hoarseness, dysphagia
