Hemodynamic Monitoring Flashcards
What is the purpose of hemodynamic monitoring?
Assess homeostasis, trends Observe for adverse reactions Assess therapeutic interventions Manage anesthetic depth Evaluate equipment function
Monitoring standards
Monitors to Be Used - Minimal Standard
1 .Electrocardiogram (HR and rhythm) 2. Blood pressure 3. Precordial stethoscope 4. Pulse oximetry 5. Oxygen analyze r6. End tidal carbon dioxide
Monitoring Information - Minimal Standard - On Graphic Display
- Electrocardiogram 2. Blood pressure 3. Heart rate 4. Ventilation status 5. Oxygen saturation
* * All alarms must be audible
Basic monitoring techniques
Inspection
Auscultation
Palpation
*Vigilance
What are some considerations regarding monitoring techniques?
A. Indications/contraindications B. Risk/ benefit C. Techniques/alternatives D. Complications E. Cost
What are the hemodynamic monitoring devices?
Stethoscope ECG BP Invasive Non-invasive CVP PAP and PCWP TEE
Describe the precordial stethoscope
Continual assessment of breath sounds and heart tones
Esophageal used in intubated patients only placed 28-30 cm into esophagus
Very sensitive monitor for bronchospasm and changes in pediatric patients
Describe the electrocardiogram monitoring?
Recording of electrical activity of the heart Standard- every patient, continuous monitoring, from beginning of anesthesia until leaving anesthetizing location Purpose- detect arrhythmias monitor heart rate detect ischemia detect electrolyte changes monitor pacemaker function
Describe the 3 lead vs. 5 lead monitoring?
3 lead:
Electrodes RA, LA, LL
Leads I, II, III
3 views of heart (no anterior view)
5 lead:
Electrodes RA, LA, LL, RL, chest lead
Leads I, II, III, aVR, aVL, aVF, V lead
7 views of heart
Gain Setting and frequency bandwidth
Gain should be set at standardization
1 mV signal produces 10-mm calibration pulse
A 1-mm ST segment change is accurately assessed
Filtering capacity should be set to diagnostic mode
Filtering out the low end of frequency bandwidth can distort ST segment
ECG indicators of acute ischemia:
5 Principle Indicators:
ST segment elevation , ≥1mm T wave inversion Development of Q waves ST segment depression, flat or downslope of ≥1mm Peaked T waves
Coronary Anatomy and ECG: Myocardial Ischemia
(Posterior)/ Inferior wall ischemia (right coronary artery) Changes in Lead II, III, AVF
Lateral wall ischemia (circumflex branch of left coronary artery) Changes in Lead I, AVL, V5-V6
Anterior wall ischemia (left coronary artery) Changes in Lead I, AVL, V1-V4
Anterioseptal ischemia (left descending coronary artery) Changes in Lead V1-V4
Blood Pressure generalities
Systolic BP-peak pressure generated during systolic ventricular contraction
Changes in SBP correlate with changes in myocardial O2 requirements
Diastolic BP-trough pressure during diastolic ventricular relaxation
Changes in DBP reflect coronary perfusion pressure
Pulse pressure=SBP-DBP
MAP-time weighted average of arterial pressure during a pulse cycle
MAP=SBP+2(DBP)/3
As a pulse moves peripherally wave reflection distorts the pressure waveform-exaggerated SBP and wider pulse pressure
Blood pressure 4 ways to measure NIBP
- Palpation- palpating the return of arterial pulse while on occluded cuff is deflated
Underestimates systolic pressure, simple, inexpensive, measures only SBP. - Doppler- based on shift in frequency of sound waves that is reflected by RBCs moving through an artery
Measures only SBP reliably. - Auscultation- using a sphygmomanometer, cuff, and stethoscope; Korotkoff sounds due to turbulent flow within an artery created by mechanical deformation from BP cuff (unreliable in HTN pts-usually lower)
Permits estimation SBP and DBP
Oscillometry- Senses oscillations/fluctuations in cuff pressure produced by arterial pulsations while deflating a BP cuff
1st oscillation correlates with SBP
Maximum/ peak oscillations occurs at MAP - Oscillations cease at DBP
Automated cuffs work by this mechanism-measure changes in oscillatory amplitude electronically, derives MAP, SBP, DBP by using algorithms.
NIBP cuffs rules
Bladder width is approximately 40% of the circumference of the extremity
Bladder length should be sufficient to encircle at least 80% of the extremity
Applied snugly, with bladder centered over the artery and residual air removed
Erroneous BP Measurement with NIBP
Falsely high BP Cuff too small Cuff too loose Extremity below level of heart Arterial stiffness- HTN, PVD Falsely low BP Cuff too large Extremity above level of heart Poor tissue perfusion Too quick deflation Also- improper cuff placement,dysrhythmias,tremors/shivering
Complications of NIBP
Edema of extremity Petechiae/ bruising Ulnar neuropathy Interference of IV flow Altered timing of IV drug administration Pain Compartment syndrome
Invasive IABP: what are its implications and what does it involve?
Involves percutaneous insertion of catheter into an artery, which is then transduced to convert the generated pressure into an electrical signal to provide a waveform Generates real-time beat to beat BP Allows access for arterial blood samples Measurement of CO/ CI/ SVR Indications Elective deliberate hypotension Wide swings in intra-op BP Risk of rapid changes in BP Rapid fluid shifts Titration of vasoactive drugs End organ disease Repeated blood sampling Failure of indirect BP measurement
How do you increase the accuracy of invasive IABP?
System dynamics and accuracy improved by minimizing tube length, limit stop cocks, no air bubbles, the mass of fluid is small, using non compliant stiff tubing, and calibration at level of heart
Accuracy depends on correct calibration and zeroing
Leveling transducer
Mid axillary line in supine pts (right atrium)
Level of the ear (circle of Willis) in sitting pts.
Dampening and overshooting
Describe the Normal Arterial Pressure Waveforms
Rate of upstroke-contractility
Rate of downstroke-SVR
Exaggerated variations in size w/ respirations-hypovolemia
Area under the curve-MAP
Dicrotic notch- closure of aortic valve
Normal arterial blood pressure waveform and its relationship to the electrocardiographic R wave.
1. Systolic upstroke; 2, systolic peak pressure; 3, systolic decline; 4, dicrotic notch aortic valve closure); 5, diastolic runoff; 6, end-diastolic pressure.
Distal Pulse Amplification
Remember arterial BP waveforms as they travel through the arterial tree to periphery— distal pulse amplification
SBP peak increases
DBP wave decreases
MAP not altered
Dicrotic notch becomes less and appears later
IABP
Nerve Damage Hemorrhage/ Hematoma Infection Thrombosis Air embolus Skin necrosis Loss of digits Vasospasm Arterial aneursym Retained guidewire
Indications of CVCs
Indications: Measuring right heart filling pressures Assess fluid status/blood volume Rapid administration of fluids Administration of vasoactive drugs Removal of air emboli Insertion of transvenous pacing leads Vascular access Sample central venous blood Pulmonary artery catheters
Describe the length, diameter, and distal placement position of CVCs
7 french
20 cm length
Multiport catheters most common
Placement usually not confirmed by XRAY in OR
Aspirate blood from all ports
After surgery, XRAY
Ideally, tip within the SVC, just above junction of venae cavae and the RA, parallel to vessel walls, positioned below the inferior border of clavicle and above the level of 3rd rib, the T4/T5 interspace, the carina, or takeoff right main bronchus
What are contraindications and risks for CVCs?
Contraindications: R atrial tumor Infection at site Risks: Risks: Usually due to poor technique Air or thrombo-embolism Dysrhythmia Hematoma Carotid puncture Pneumo/hemothorax Vascular damage Cardiac tamponade Infection Guidewire embolism
What is the normal CVP and normal pressure?
The waveforms result from ebbs and flows of blood in the right atrium.
CVP pressures = RAP = RV preload.
A mean RA pressure in a spontaneously breathing patient is approximately 1-7 mmHg
This rises about 3-5 mmHg during mechanical ventilation
Measuring CVP
The peak of the “a” wave coincides with the point of maximal filling of the right ventricle
Therefore, this is the value which should be used for measurement of RVEDP
Machines just “average” the measurement
Should be measured at end-expiration
CVP Waveform
5 Phasic Events Three Peaks (a, c, v) Two Descents (x, y) “a” wave Due to contraction of the right atrium, which results in increased pressure in the atrium (since there is no pressure difference between the vena cava and the atrium)
“a” wave
“a” wave
Due to contraction of the right atrium, which results in increased pressure in the atrium (since there is no pressure difference between the vena cava and the atrium)
Caused by atrial contraction (follows the P-wave on EKG)
End diastole
Corresponds with “atrial kick” which causes filling of the right ventricle
“c” wave
“c” wave
Due to closure of the tricuspid valve and isovolemic ventricular contraction; results in the tricuspid valve “bulging” back into the atrium.
Atrial pressure decreases after the “a” wave as a result of atrial relaxation
The “c” wave is due to right ventricular contraction; tricuspid valve closed bulges back into the right atrium
Occurs in early systole (after the QRS on EKG)
“x” descent
Atrial pressure continues to decline during ventricular contraction due to atrial relaxation
“Systolic collapse in atrial pressure”
Mid-systolic event
“v” waveform
“v” wave
Reflects venous return against a closed tricuspid valve (which encompasses a portion of RV systole)
The last atrial pressure increase is caused by filling of the atrium with blood from the vena cava
Occurs in late systole with the tricuspid still closed
Occurs just after the T-wave on EKG
“y” descent
“y” descent
After ventricular relaxation, the tricuspid valve opens due to the venous pressure, and blood flows from the atrium into the ventricle.
The y descent is the fall in atrial pressure following opening of the tricuspid valve.
Decrease in atrial pressure as the tricuspid opens and blood flows from atrium to ventricle
“Diastolic collapse in atrial pressure”
Pulmonary Artery Pressure Monitoring used for direct bedside assessment of?
Right-sided heart catheter used for direct bedside assessment of : Intracardiac pressures (CVP, PAP, PCWP) Estimate LV filling pressures Assess LV function CO Mixed venous oxygen saturation PVR and SVR Pacing options
Pulmonary Artery Pressure Catheters size and dimensions
7 or 9 french 110 cm length marked at 10 cm intervals 4 lumens distal port PAP second port 30 cm more proximal CVP third lumen balloon forth wires for temp thermister
Pulmonary Artery Pressure Monitoring indications:
Indications: LV dysfunction Valvular disease Pulmonary HTN CAD ARDS/ resp failure Shock/sepsis ARF Surgical procedure: cardiac, aortic, OB
PA catheter complications
Arrhythmias (including V-fib, RBBB, complete heart block)
Catheter knotting
Balloon rupture
Thromboembolism; air embolism
Pneumonthorax
Pulmonary infarction
PA rupture
Infection (endocarditis)
Damage to cardiac structures (valves, etc.)
Relative Contraindications– WPW syndrome, Complete LBBB
PCWP a and c waveforms
The ‘a’ wave represents contraction of the left atrium. Normally it is a small deflection unless there is resistance in moving blood into the left ventricle as in mitral stenosis.
The ‘c’ wave is due to a rapid rise in the left ventricular pressure in early systole, causing the mitral valve to bulge backward into the left atrium, so that the atrial pressure increases momentarily.
PCWP’ v’ waveforms
The ‘v’ wave is produced when blood enters the left atrium during late systole.
Prominent ‘v’ wave reflect mitral insufficiency causing large amounts of blood to reflux into the left atrium during systole.
Cardiac output monitoring
Thermodilution Continuous thermodilution Mixed venous oximetry Ultrasound Pulse Contour
Factors That Can Distort CVP and PAOP Waveforms
Loss of a waves A fib Ventricular pacing Giant a waves “Cannon” a waves Junctional rhythms Complete HB Mitral stenosis Diastolic dysfunction Myocardial ischemia Ventricular hypertrophy Large v waves Mitral regurgitation Acute increase in intravascular volume
Transesophageal Echocardiography 7 cardiac parameters observed
7 Cardiac Parameters Observed Ventricular wall characteristics and motion Valve structure and function Estimation of end-diastolic and end-systolic pressures and volumes (EF) CO Blood flow characteristics Intracardiac air Intracardiac masses
Transesophageal Echocardiography uses:
Uses: Unusual causes of acute hypotension Pericardial tamponade Pulmonary embolism Aortic dissection Myocardial ischemia Valvular dysfunction
Transesophageal Echocardiography complications:
Complications: Esophageal trauma Dysrhythmias Hoarseness Dysphagia
Most complications in awake patients
