Hemodynamic Monitoring Flashcards
How far is an esophageal stethoscope inserted into the esophagus?
28-30cm. This allows us to hear heart sounds and BS internally.
What are precordial and esophageal stethoscopes useful for?
Continuous assessment of heart and breath sounds. Very sensitive monitor for bronchospasm and changes in pediatric patients
How often should we have a regular stethoscope available?
At all times
What 4 general things are continually evaluated?
Oxygenation, ventilation, circulation, and temperature
Considerations in deciding what type of monitoring to use
1) Indication
2) Risk/benefit
3) Complications
4) Alternatives
5) Cost
6) Skill level
Types of hemodynamic monitoring used
EKG, BP (NIBP and IABP), CVP, PAP, PCWP, TEE, stethoscope
What can the EKG tell you?
Heart rate, arrhythmias, Ischemia, electrolyte imbalances, pacemaker function
Aspects of the 3 Lead EKG
Electrodes used: RA, LA, LL
Leads: I, II, III
Number of views of the heart: 3
Aspects of the 5 lead EKG
Electrodes used: RA, LA, RL, LL, chest
Leads: I, II III, AVL, AVR, AVF, V lead
Number of views of the heart: 7
Value of the length and width of each EKG box
.1mV and .04s
How to calculate HR based on EKG lead
1500/# boxes between R waves
How should the gain be set in order to accurately assess the ST segment?
At standardization (1mV signal gives a rise of 10mm). This setting also fixes the ratio of the QRS complex to the ST segment size so that a 1mm change in the ST segment can be accurately assessed. If the wrong gain setting is used, ST changes may be under or over-diagnosed.
What filtering mode should the EKG be on for accurate ST assessment?
Diagnostic mode. Filtering out the low end of frequency bandwith (which can happen on monitor mode) can lead to ST distortion (either elevation OR depression)
5 main indicators of acute ischemia
ST elevation ( >1mm), ST depression ( >1mm), flipped Ts, peaked Ts, development of Q waves
Posterior / inferior wall ischemia is seen in these leads and is due to a blockage in this artery
II, III, AVF
Right coronary
Lateral wall ischemia is seen in these leadsand is due to a blockage in this artery
I, AVL, V5-6
Left circumflex coronary artery
Anterior wall ischemia is seen in these leadsand is due to a blockage in this artery
I, AVL, V1-4
Left coronary artery
Anterioseptal wall ischemia is seen in these leads and is due to a blockage in this artery
V1-4
Left anterior descending coronary artery
This part of BP correlates to the point of the most demand on the heart
SBP
The pulse pressure changes as you move from where to where
From the central arterial system to the periphery. The pulse pressure widens due to wave reflections in the vasculature.
These factors can cause a falsely high NIBP reading
Cuff too small, cuff below the level of the heart, loose cuff, arterial stiffness (HTN, PVD)
These factors can cause a falsely low NIBP reading
Cuff too large, cuff above the level of the heart, poor tissue perfusion, deflation is too rapid
Fals NIBP reading can also occur with
Cardiac dysrhythmia, tremors/shivering/ and improper cuff placement
This type of NIBP reading only gives you SBP
Palpation. It measures the return of arterial pulse during deflation. This is simple, inexpensive, and underestimates the SBP.
This NIBP reading only gives you SBP but measures it fairly reliably
Doppler. Measures it by a shift in frequency of sound waves that is reflected by RBCs moving through an artery.
This NIBP method estimates both SBP and DBP
Auscultation with a sphygmomanometer. Measures BP by auscultation Karotkoff sounds created by turbulent blood flow though the artery created by the mechanical deformation from the BP cuff. This method is unreliable in patients with HTN.
Changes in SBP correlate with changes in ____
Myocardial O2 demand.
Automated cuffs work by this mechanism
Oscillometry
Complications of NIBP measurement
Ulnar nerve damage, compartment syndrome, edema of the extremity, bruising / petechiae, pain, interference of IV flow, altered timing of IV drug administration
Indications for IABP monitoring
1) Deliberate hypotension
2) Risk of rapid BP changes
3) Wide swings in BP intra-op
4) Rapid fluid shifts
5) Titration of vasoactive drugs
6) End organ disease
7) Repeated blood sampling
8) NIBP measurement failure
What test has to be done before radial a-line placement?
Allen’s test
Rate that NS moves through the a-line system to prevent clot formation
1-3mL/hr
How can a-line dynamics and accuracy be improved?
Remove bubbles, calibrate at the level of the heart, limit tube length and number of stop-cocks, use non-compliant stiff tubing, and make sure the mass of the fluid used is small
Where should the a-line be calibrated?
Supine patients- midaxillary line (right atrium)
Sitting patients- level of the ear / circle of willis because we are concerned about CBF
Rate of a-line upstroke tells you about
Contractility
Rate of a-line downstroke tells you about
SVR
Exaggerated variations in a-line tracing size with respirations indicates
Hypovolemia
The area under the a-line curve tells you
MAP
The dicrotic notch indicates the closure of this valve
Aortic valve
What happens to IABP readings as they move further into the periphery?
Distal pulse amplification!
This causes increased SBP, decreased DBP, and increased pulse pressure. MAP remains unchanged. The dicrotic notch becomes less and less apparent and appears later in the tracing (takes longer for the pressure wave to reach the transducer).
Complications of IABP measurement
Nerve damage, hemorrhage/hematoma, retained guidewire, infection, thrombosis, air embolus, arterial aneurysm, vasospasm (usually self-limiting), skin necrosis, loss of digits
Are fluids able to be given faster through a PIV or central line?
PIV
Indications for getting central access
Need more vascular access (unable to get enough PIVs) and need to rapidly give fluids, give vasoactive meds, monitor CVP, assess fluid status/blood volume, sample venous blood, remove air emboli, pulmonary artery access, insertion of transvenous pacing leads
Why is the right IJ preferred to the left
It provides a more direct route to the heart and the dome of the lung is higher on the left
Typical central venous catheter size
7 french
20cm
If anesthesia places a central line, is placement confirmed with an x-ray?
No, it is confirmed with blood aspiration from all 3 ports. X-ray is taken after surgery.
Where should the tip of the central line be located?
Just above the RA at the SVC/RA junction and parallel to the vessel walls. Should be at the level of the 3rd rib or the T4/5 interspace or the level of the carina or R mainstem bronchus.
When is a central line contraindicated?
R atrial tumor
Injection at site of desired placement
Central line risks
Thrombo-embolism, air embolism, guidewire embolism, carotid puncture, hematoma, dysrhythmia, pneumo/hemothorax, vascular damage, cardiac tamponade, infection
What does CVP measure?
CVP measures the RAP (because it’s right at the RA junction), which is a measure of preload
Normal RA pressure in a spontaneously breathing patient is ______ and it rises by _______ during mechanical ventilation
1-7mmHg
3-5mmHg
How is RVEDP measure with CVP tracing?
The a wave at end-expiration, which correlates with maximal filling of the right ventricle.
What is the a wave?
Contraction of the right atrium, which results in increased RAP.
The a wave follows this on the EKG
The p wave.
This CVP wave is the atrial kick
The a wave
What is the c wave a reflection of?
Isovolumetric contraction of the right ventricle, resulting in the bulging back of the tricuspid valve into the RA
The c waves follows this waveform on the EKG
The QRS complex. The c wave occurs in early systole
The x descent occurs during
Mid-systole. The x descent follows the c wave.
The v wave reflects what?
Venous return into the RA against a closed tricuspid valve
When does the V wave occur during the cardiac cycle and EKG?
At the end of systole with the tricuspid valve still closed, and it occurs just after the T wave.
What does the y descent reflect?
Passive ventricular filling after ventricular relaxation. The y descent reflects a fall in RAP due to this. This is referred to the “diastolic collapse in atrial pressure”
Size of pulmonary artery catheters and number of lumels
7-9 french
110cm
4 lumens (distal is for PAP, second is 30cm proximal for CVP, third is for balloon, and fourth is for the thermistor wires)
Indications for PAP monitoring
1) Unstable cardiac patients
2) LV dysfunction
3) Pulmonary HTN
4) ARDS/resp failure
5) Shock/sepsis
6) ARF
7) CAD
8) Valvular disease
9) Surgical procedures, such as cardiac, aortic, or OB
Complications of pulmonary artery catheters
Arrhythmias (v-fib, RBBB, complete heart block)*** PA rupture**** Balloon rupture Pulmonary infarction Thromboembolism/air embolism Pneumothorax Catheter knotting Damage to cardiac structures (valves) Infection (endocarditis)
Relative contraindications to a PA catheter
WPW syndrome
Complete LBBB
Distance from right IJ to various structures
SVC/RA junction- 15cm RA- 15-25cm RV- 25-35cm PA- 35-45 PA Wedge 45-50
If you go beyond these measurements and don’t see the proper waveform, you may be coiling the catheter
When might the a wave be larger than normal
Mitral/tricuspid stenosis
When might the v wave be larger than normal?
Mitral/tricuspid insufficiency, causing blood to reflux into the atrium during systole. Remember that the v wave reflects atrial filling during late systole
Ways that we can measure CO
Thermodilution, continuous thermodilution, ultrasound, TEE, pulse contour, and mixed venous oximetry
“a” waves may be lost with
a-fib or ventricular pacing
Giant a waves (“Cannon” a waves) may be caused by
Junctional rhythms, complete HB, mitral stenosis, diastolic dysfunction, myocardial ischemia, ventricular hypertrophy
Large V waves may be caused by
Mitral/tricuspid regurgitation
Acute increase in intravascular volume
7 things you can observe with TEE
1) CO
2) Ventricular wall characteristics and motion
3) Valve structure and function
4) Measurement of EDV and ESV
5) Blood blow characteristics
6) Intracardiac masses
7) Intracardiac air
When is the use of TEE indicated?
1) Pericardial tamponade (for trauma)
2) Unusual causes of acute hypotension
3) PE
4) Aortic dissection
5) Myocardial ischemia
6) Valvular dysfunction
Overall, if someone is still very unstable and unresponsive to our treatments, we can use TEE to get a better overall picture of our patients- checking to see what the actual structural problem might be
Complications of TEE
Esophageal trauma
Dysphagia
Hoarseness
Dysrhythmias
Most complications are reported in awake patients
