chapter 3 monitoring Flashcards
What are indications for EKG in anesthetized patient (4)
1)diagnosis of dysrhythmias, 2)diagnosis of ischemia 3)diagnosis of conduction defects 4)diagnosis of electrolyte distrubances
What are best leads for determining an inferior MI
II, III, AVF
What are best leads for determining lateral MI
I, AVL
Which lead is preferable for cardiac surgical patients
V5-single best lead for diagnosis of myocardial ischemia
best when analyzed with lead II (90% of ischemic episodes)
What are limitations of using 3 lead system vs. 5 electrode system
3 lead-right arm, left arm, and left leg
limits areas of monitoring to anterior, lateral, and inferior walls
Advantages of 5 lead system
5 lead system is all limbs plus unipolar precordial lead(V5 position, or right precordium to monitor Right wall)
7 different leads can be monitored, all but posterior wall can be monitored for ischemia
name bipolar leads, unipolar leads augmented leads
Bipolar I, II, III (monitor + and- electrical potential b/t leads
unipolar augmented AVR, AVL, AVF (one is positive, determine absolute electrical potential between 3 leads)
what is esophageal lead sensitive for
with esophageal stethoscope, atrial dysrhythmias, posterior ischemia
what is tracheal ECG leads good for
pediatric patients for atrial dysrhythmias
what are epicardial electrodes used for
ventricular/atrial wires good for weaning off of CPB before sternal closure, recording of atrial or ventricular epicardial EKG, post operatively to diagnosis conduction issues/dysrhythmias
risks associated with ECG
minimal-microshock
Will non invasive blood pressure work during CPB?
no, must use invasive mechanisms, as pulsatile blood flow is absent in these patients
what are components of invasive BP monitoring
intravascular catheter, fluid filled tubing, transducer, electronic analyzer/display system
critically dampened art line, under dampened, over dampened art line correlate to what type of heart rates
critically dampened HR >150, under dampened, low HR and overestimation od systolic and underestimation of diastolic, and over dampened underestimate of systolic and overestimate of diastolic
describe most transducer systems in anesthesia
under dampened systems with low natural frequency
what effect does air have on invasive BP monitoring
leads to over dampening of system (underestimate of systolic, overestimate of diastolic
describe catheter whip
noticeable pressure swing in PA or LV catheters
describe radial arterial pressure in relation to aortic pressure
radial arterial pressure 20 to 50 mmHG higher than aortic pressure due to decreased peripheral arterial elastane and wave summation
aortic wave form vs. femoral vs.dorsals pedis waveform
aortic rounded, definite dicrotic notch
femoral-delay in pulse transmission (higher systolic pressure) and slurring
dorsals-loss of dicrotic notch, second wave due to arterial arteriolar impedance mismatch
where is reference position for transducer in hemodynamic monitoring
at the right atrium
what are indications for arterial pressure monitoring in cardiac patient
1)small changes in arterial perfusion pressure increase patient risk requiring beat to beat assessment 2)wide variation in BP or intravascular volume is anticipated, 3)frequent blood sampling, 4) assessment of BP can not be performed by other methods (CBP no pulsatile flow) dysrhythmia, or marked obesity)
what are advantages of using femoral artery for invasive BP
1)assessment of central venous pressure 2) access for intra aortic balloon pump
if difficult weaning from CPB is expected (depressed EF, severe wall motion abnormalities, or significant CAD)
*seldinger technique
other areas for arterial BP
radial, ulnar, femoral, axillary, brachial, dorsalis pedis, posterior tibial arteries can all be used
describe respiratory variation in waveforms in relation to hypovolemia
decrease in arterial systolic pressure with PPV (pulses paradox) with PPV impeding venous return to the heart and will seen in hypovolemia
other arterial artery assessments-contractility, SV, vascular resistance-describe
contractility(rate of rise during systole effected by preload, and after load and HR), SV(area under curve from onset of systole to dicrotic notch), vascular resistance(position of dicrotic notch with a notch appearing high on downslope of pressure tracing suggesting high resistance, low resistance causes a dicrotic notch that is low not diastolic portion of the pressure tracing)
what are 5 complications of arterial catheterization
ischemia, thrombosis, infection, bleeding and false lowering of radial artery pressure may be significantly lower than aortic pressure at completion of CPB with forearm vasodilation secondary to rewarming leading to AV shunting resulting in steal phenomenon
what does CVP measure
RA pressure, affected by circulating blood volume, venous tone, and RV function
what can CVP monitor
fluid and drug therapy, decision to insert CVP to PA catheter
most common place for CVP
IJ-contraindicated in carotid artery disease, recent cannulation of IJ vein, thyromegaly or prior neck surgery.
what should you be careful of in left IJ insertion
be careful of inserting left IJ because of close proximity to thoracic duct and laceration of left brachiocephalic vein or SVC is more common
IJ landmarks Central technique
SCM Apex triangle formed by lateral clavicular and medial sternal head of SCM aim needle caudally and laterally toward ipsilateral nipple
why not use EJ for CVP
courses superficially along SCM, joins subclavian close to junction of IJ, more tortuous, presence of valves more diffuclt
IJ anterior technique
medial border of medial head, 5cm above clavicle direct needle toward ipsilateral nipple
name 3 positive waves of CVP, 2 negative waves
ACV positive
x y negative descents
describe A cannon waves
when AV disassociation occurs, RA contraction occurs against a closed tricuspid valve
describe V waves
tricuspid valve insufficiency with retrograde flow across incompetent valve produces an increase in ra pressure during systole
CVP
RV filling pressure, can be used to estimate LV filling pressures but are distorted in LV dysfunction, decreased LV compliance(ischemia) valvular disease of mitral valve, or pulmonary HTN
when does CVP correlate well with PCWP
when patients with CAD have good EF >40 and no regional wall abnormalities but compliance of RV is higher than that of lv because RV is thinner walled in comparison
Pulmonary artery pressures
RV function, pulmonary vascular resistance, left atrial filling pressure
PCWP
more direct LA filling pressure
A, C, V in correlation with ECG
A wave-p wave atrial systole
C wave QRS bulging of blood against tricuspid valve during systole
V wave-after the T wave atrial filling
Why is the PA diastolic pressure, La pressure and LVEDP greater than RA pressure and RVEDP?
during diastole, pulmonic valve is closed
patients with differences in RV and LV function
volume status difficult to determine because of disparity bt CVP and PCWP-myocardial ischemia, LV dysfunction, PPV
Right ventricular failure findings
increase in CVP, decrease in CVP to mean PA gradient, and a low CO
Left ventricular failure
high PA pressures and wedge pressures in the presence of systemic hypotension and low cardiac output
tricuspid valve stenosis
CVP to RV end diastolic pressure gradient
pulmonic valve stenosis
rv to pa systolic pressure gradient and CVP waveform morphology
mitral valve insufficiency
pa and wedge pressure morphology
mitral insufficiency= abnormal v waves and increase in pulmonary venous pressure from regurgitant flow-myocardial ischemia, ventricular pacing, and presence of VSD
PA cath with ischemia
decrease in ventricular compliance, either an increase in PA pressure or an increase in PCWP, and pathologic V waves from injury to papillary muscles
PEEP >10
effects PA valves
Mixed Venous O2 Saturation normal value
normal is 75 with a 5 to 10% increase clinically significant
4 things that mixed venous O2 sat can tell you
1) decrease in CO
2) decrease in HGB concentration
3) decrease in arterial O2 saturation
4) increased O2 extraction
preferred site for PA cath
right IJ followed by left subclavian
Thermodilution technique
for CO
room temp saline injected in RA, temperature sensor in PA cath determines change in temp/time with is a value for PV output, which is equal to CO if no shunts are present 3 measurements, most likely within 10% of true CO
increase of thermodilution injectatae by 1 degree C will result in
3% overestimate of CO
limitations to TEE
diseases near distal ascending aorta, proximal aortic arch because airway interferes with TEE signal
temps below 32, above 41
below 32 irritable myocardium, Vtach, v fib
above 41enzyme desaturation and cell damage
acute renal failure
2 31% of all cases after CPB
use of mannitol during CPB
hemodialysis, serum HGB rise maintain urine output to avoid damage to renal tubules
and deliberate hemodilution induced with onset of hypothermic CPB allows removal of excess free water
best assessment of renal function during CPB
urinary catheter
serum electrolytes
k and Mg usually decline secondary to mannitol and improved person, cardiopelegia contains K, so replace with caution, and ionized ca replacement may worsen neurological ischemia, only replace ca after reprofusion is established after aortic clamp remove;
microshock
50-100mA, cardiac patients often have indwelling catheters that lead directly to the heart, pace wires, etc. these patients more at risk, and mocroshock cannot occur unless skin resistance is bypassed-vfib common
act
heparin monitoring activated clotting time greater than 400 adequate
TEG
thromboelastography-functional info about platelets, clotting factors, and fibrinolytic processes
glucose in period cardiac patient
treat when greater than 200 measure q 30-60 min
