Monitoring - Quiz 2 Flashcards by Kristen Nelson

What causes the most pressure monitoring errors?

air within a catheter or transducer

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What is the recommended mode of monitoring temp on a cardiac surgical pt? (CSP)

One core site (nasal) AND

One shell site (bladder or rectal)

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True or False. Although low serum Ca may affect myocardial pumping fx, admin of Ca during potential neural ischemia or repercussion may likely worsen the outcome and should be avoided.

True

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Which EKG leads are most useful for monitoring the inferior wall of the heart?

II, III, aVF

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Which EKG leads are most useful for monitoring the lateral wall of the heart?

I, aVL

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Where is the precocial unipolar lead placed to best monitor the LV?

V5 position along the anterior axillary line in the 5th intercostal space

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The best single lead in diagnosing myocardial ischemia in a pt w CAD

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> 90% of ischemic episodes will be detected by EKG is which 2 leads are analyzed simultaneously?

leads II and V5

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How can one monitor for posterior wall ischemia?

7- lead system or esophageal lead

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most useful leads in the post-op dx of complex conduction problems and dysrhythmias

AV pacing wires (epicardial electrodes)

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None of the standard EKG leads can detect ischemia in which 2 locations?

posterior wall

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How well do noninvasive monitoring devices function when pulsatile blood flow is absent (during CPB or LVAD use)

They don’t.

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True or false: Correct damping of a pressure-monitoring system should not affect the natural frequency of the system

true

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A system that overestimates SBP and underestimates DPB would be ____damped

Underdamped

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A system that underestimates SBP and overestimates DBP would be ____damped

Overdamped

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An optimally or critically damped system will exhibit a ________ frequency response in the range or frequencies up to the natural frequency of the system

constant/flat

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critical part of a transducer that acts to link fluid wave to electrical input

diaphragm

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True or False: most transducer systems used in clinical anesthesia can be described as underdamped systems with low natural frequency

true

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Systolic pressure measured in a radial A line may be up to ___ - ___ mmHg higher than aortic pressure. WHY?

20-50 mmHg

because of decreased peripheral arterial elastance and wave summation

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What is the most common site used for arterial cannulation? Why?

Radial artery

it is convenient
it provides a reasonably accurate estimation of the true aortic pressure

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What indicates limited collateral ulnar artery flow into the hand?

positive Allen’s test

even w a positive Allen’s test, radial artery cannulation still has had very few ischemic complications

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True or False: The distal location of DP and PT arterial line sites leads to increased distortion of the arterial wave.

True.

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Factors that may cause a narrow pulse pressure on an A-line

pericardial tamponade

hypovolemia

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factors that may cause an increased pulse pressure on an A-line

worsening aortic valvular insufficiency

hypovolemia

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A decreased SBP with PPV suggests....

Hypovolemia Positive intrathoracic pressure impedes venous return to the heart w a more pronounced effect in a hypovolemic pt

Rate of pressure rise during systole can reflect...

contractility | HR, preload, and after load can affect it tho

area under the aortic pressure wave from the onset of systole to the dicrotic notch can reflect....

Stroke volume

Position of the dicrotic notch on the A-line wave form correlates w....

SVR | high notch = high SVR; low notch = low SVR

What has more risk of thrombus development, A-lines or central venous catheters? Why?

A-lines because they are not heparin bonded

Why is radial artery pressure significantly lower than aortic pressure at completion of CPB?

1. forearm vasodilation secondary to rewarming may lead to A-V shunting, resulting in steal phenomenon 5-30 min longer in duration OR 2. hypovolemia and vasoconstriction

most common IV access route in cardiac anesthesia

internal jugular vein

Relative contraindications for IJ central line placement

1. presence of carotid dz 2. recurrent cannulation of IJV (thrombus risk) 3. contralateral diaphragmatic dysfunction 4. Thyromegaly or prior neck surgery

What site is recommended as the first option for PAC placement?

L subclavian

A "Cannon A wave" on a CVP indicates ________

AV dissociation RA is contracting against a closed tricuspid valve

Abnormal V wave on CVP indicates _______

tricuspid valve insufficiency retrograde flow through the incompetent valve --> increased RA pressure during systole

PA pressure reflects....

1. RV fx 2. PVR 3. LA filling pressure

PCWP is a more direct estimate of

LA filling pressure a valveless hydrostatic column exists b/t the distal port and the LA at end-diastole

2 indications that cannot be performed w CVP alone

1. differentiation of L vs R ventricular fx | 2. assessment of intracardiac filling pressures during cardioplegia administration

Increase in CVP Decrease in CVP to mean PA gradient Low CO ...all indicate _______

RV failure

hallmarks of LV failure

simultaneous readings of high PA pressures and PCWP in the presence of systemic HoTN and low CO

if the PA diastolic and wedge pressures do not agree closely with one another, what would you suspect is occurring?

Pulm HTN

Primary diagnostic modality for tricuspid and pulm valve stenosis in adults

TEE

increase in PA pressure or increase in PCWP reflects a decrease in ventricular compliance. What would this be associated with?

Significant ischemia

The established convention is to evaluate PA pressures during which part of the breathing cycle?

end expiration

4 mechanisms that may result in decreased SvO2

1. decreased CO 2. Decreased hgb concentration 3. decreased arterial O2 sat 4. increased O2 utilization

True or False: Changes in SvO2 usually precede hemodynamic changes by a significant period of time.

True

most common complication associated w PAC insertion

dysrhythmias

Which approach offers the most direct route to the RA and thus results in the highest rate of successful PA catheterization? Which approach is next most effective?

R IJ L subclavian

most common arrhythmia during PAC placement

PVCs usually resolved with either catheter withdrawal or with advancement of the catheter tip from the RV into the PA

The PAC should not be advanced more than _______ from the RIJ approach because this increases the risk for PA rupture or catheter knotting

60 cm

Although thrombus formation of PACs has been noted at 24h, the incense of thrombogenicity substantially increases by ________

72 hrs

How is a CO measurement altered with R sided valvular lesions when using the thermodilution method? How is it altered with mitral or aortic valve lesions?

CO is underestimated w RV valvular lesions CO remains accurate for forward LV CO for LV valvular lesions

5 factors that may alter the CO reading from normal when using the thermodilution method

1. Volume of injectate (less volume = falsely higher CO volume and vice versa) 2. Temp of injectate (increase 1*C = 3% overestimation of CO 3. Shunts 4. Timing with resp cycle 5. Catheter position (must be in PA but not wedged)

practical gold standard for evaluating CO

PAC | thermodilution method is most commonly utilized

True or False: Adequacy of perfusion is likely when a pulse oximeter shows a saturation reading.

True because the pulse ox utilizes plethysmography as part of its basic operation

3 factors for which EtCO2 offers evidence

1. endotracheal intub 2. ventilation 3. perfusion

What does core temperature represent?

The temp of the vital organs

How does hypercarbia affect PA pressures and RV fx?

increases PA pressures | worsens RV fx

Why should an esophageal temp probe not be routinely used for cases involving CPB?

the esophagus will be greatly affected by the temp of the blood returning from the extracorporeal pump

Shell temperature represents

the temp of the majority of the body (musc, fat, bone) which receives a smaller portion of the blood flow

single most important monitor of renal rx during surgical cases involving CPB

Urinary catheter

Which 2 electrolytes typically decline during CPB?

K and Mg

What is the basic principle of clinical EEG monitoring?

cerebral ischemia causes slowing of the electrical activity of the brain, as well as a decrease in signal amplitude

True or False: Microshock cannot occur unless the skin resistance has been bypassed.

True

Most common means of monitoring adequate heparin effect

ACT (activated clotting time)

What ACT level is adequate during CPB?

>400s (if off pump CABG cases using partial heparinization, ACT target is ~300s

How often should blood glucose be measured during cardiac surgery, and at what level should an insulin gtt be started?

q 30-60 min 200 mg/dL