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Life Support #2
Monitoring Systems (A-line)
| Question | Answer |
|---|---|
| Components of a Fluid Filled monitoring system | intravascular catheter, low compliance tubing, transducer, amplifier/monitor, continuous flush system |
| The intravascular catheter is semi- ___ and provides access to ___ ____, _____ | rigid;central veins, arteries |
| The low compliance/____ tubing connects what to what? | rigid; intravascular catheter to transducer |
| Max length of the low compliance tubing should be | no greater than 3-4 ft |
| This receives low voltage electrical signal from the transducer and increases the signal amplitude to be displayed on the monitor | Amplifier/monitor |
| The amplifier/monitor responds rapidly to changes, creating real time display correlating with ___ | ECG |
| The flush system continuously flushes fluid through the system at a rate of __ml/hr | 3 |
| Each beat of the heart generates a __ ___ __ (arterial pulse) | complex pressure wave |
| The arterial pressure is propagated through systemic circulation at a given ____ | frequency (bpm)( |
| The resulting sine wave is called the first ___ | harmonic |
| Phase I of the arterial pressure waveform = | early systole, inotropic component |
| The steepness, rate and height of the anacrotic rise in Phase I are related to | stroke volume and LV contraction |
| What is Phase II of the arterial pressure waveform? | Systole, Volume displacement curve, Continued ejection of SV from ventricle |
| What is Phase III of the arterial pressure waveform? | Late systole and Diastole, Sloping decline, dicrotic notch |
| This Phase of the arterial pressure waveform has the anacrotic notch and volume displacement curve | Phase II |
| This Phase of the arterial pressure waveform consists of the anacrotic rise (inotropic component) | Phase I |
| What is Damping? | Friction that slows down and reduces the amplitude of oscillations |
| What are the 3 damping factors? | Elasticity(compliance of pressure tubing), Mass of fluid in tubing and cath, and Friction(viscosity and flow of the fluid/blood) |
| Underdamped waveform appears | narrow, peaked |
| Effects of underdamped waveforms on BP measurements | Overestimates/Inaccurately high SBP; Underestimates/inaccurately low DBP |
| What can cause an underdamped waveform? | long tubing |
| Overdamped waveform appears how | Widened and slurred, dicrotic notch not clearly visible |
| Overdamped effects on BP measurements | underestimates/inaccurately low SBP, Overestimates/inaccurately high DBP |
| Causes of overdamped waveform | air bubbles, overly compliant tubing, kinks, clots, stopcocks |
| The ability of a fluid filled monitoring system to accuraely reproduce the true pressure pulse on the monitor is called | Dynamic response |
| What is the name of the test for dynamic response? | Square wave/fast flush/snap test |
| If the fast flush test generates numerous oscillations that extend below baseline, what kind of system does that indicate? | underdamped |
| If the fast flush test generates no oscillations below the baseline (no "ringing" after flush), what kind of system does that indicate? | overdamped |
| Use ___, not SBP or DBP for monitoring bc ___ is less subject to error | MAP |
| 2 reasons for having an A-Line | frequent blood draws and BP monitoring |
| 4 ways to insure accuracy of fluid filled monitoring system | unobstructed, zeroed, leveled, and calibrated properly |
| What is the number 1 cause there is no waveform? | stopcock turned off to patient |
| Troubleshooting: no waveform, what do you do? | check for kink, clot(aspirate first, do not flush), Check stopcock not off to pt, check pressure bag setting, check for loose connections, verify zero and level |
| What causes artifact? | catheter whip |
| If you see Artifact what should you do? | check pt movement, perform dynamic response testing to determine underdamping |
| Steps to assemble A-line | collect equipment, puncture flush bag, attach pressure bag, tighten connections, prime press. tubing with flush soln changing stopcocks as you progress, inflate bag to 300mmHg, inspect for kinks/bubbles, connect to monitor, level and zero, connect to pt. |
| Blood pressure is _____ at all points in the arterial system, _____ affects BP | not equal; gravity |
| ABP ____ downward from the heart level and _____ upwards from the heart level | increases; decreases |
| Why should all BP measurements be taken at the heart level? | to eliminate the affect of gravity on hydrostatic pressure |
| Leveling eliminates this type of pressure | hydrostatic |
| This is an accurate reference to establish a standard neutral level for all measured pressures | zeroing |
| Zeroing eliminates this type of pressure | atmospheric |
| Where is the phlebostatic axis? | midaxillary line, level of RA, 4 ICS, 1/2 AP diameter |
| Intravascular volume(Preload), Pump efficiency, SVR, and PVR(afterload) are all effected by what during Systole? | Stroke volume |
| What is stroke volume? | the volume of blood ejected from the heart with each beat |
| These factors influence ABP during Diastole | Vascular resistance(SVR, PVR), vascular tone, heart rate |
| How does heart rate affect diastolic pressure? | it changes the duration of diastole and the pressure continues to fall until next systole |
| SVR equation and Norm | SVR=[(MAP-CVP/CO) x80] Norm: 770-1500 dynes/sec/cm-5 |
| PVR equation and Norm | PVR=[(MPAP-PWP/CO) x80] Norm: 20-120 dynes/sec/cm-5 |
| What causes ABP to decrease? | Hypovolemia, vasodilation(shock, vagal stimulation), cardiac failure |
| What causes ABP to increase? | Vasoconstriction(sympathetic stimulation, vasopressors), improvement in circulating volume, Increase in Stroke Volume |
| What is compensatory vasoconstriction? | vasoconstriction maintains ABP within acceptable range even though significant decreases in intravascular volume or SV may be present |
| What may still exist with compensatory vasoconstriciton? | organ hypoperfusion |
| This is an early sign of changes in circulating blood volume? | Changes in Pulse pressure |
| Pulse pressure is directly related to what? | acute changes in SV; SV increases=PP increases, SV decreases=PP decreases |
| Normal PP range | 25-80mmHg |
| Mean PP | 40mmHg |
| low pulse pressures can indicate what 2 things? | CHF and shock |
| What can cause high pulse pressures | Stiff arteries, aortic regurgitation |
| What is the average driving force in the arterial system throughout the cardiac cycle known as? | Mean arterial pressure |
| MAP is used to calculate what? | SVR and PVR |
| Normal MAP is | 70-105 |
| MAP below 60 indicates | circulation to vital organs may be compromised and poor tissue perfusion |
| Why does SBP become progressively higher toward the peripheral arteries? | bc they are narrower |
| MAP is less affected by what 2 things ? | motion artifact and damping factors |
| When is MAP not reliable? | HR > 120 |
| Systolic measurements by cuff may be __mmHg lower than arterial SBP | 20mmHg |
| Diastolic measurements by cuff may be generally __ than arterial DBP | higher |
| indications for Arterial cannulation | hemodynamically unstable pt, pt on vasoactive drips (EPI, dopamine), pt with IAB, Perioperative pt |
| Contraindications of arterial cannulation | hemorrhagic disorders, anticoagulant therapy, thrombolytic agents, Site specific: dialysis shunt, infection, grafts, vascular surgery, negative allens test |
| This insertion site is the largest vessel, useful in cardiopulmonary arrest | femoral |
| Order of arterial insertion sites | radial, brachial, pedal or femoral, axillary |
| Hazards of arterial cannulation | hemorrhage, thrombus, air embloli, systemic infection, site infection, arterial spasm, vascular occlusion |
Created by:
Dabi2
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