Hemodynamic monitoring Flashcards
What are 5 purposes of hemodynamic monitoring?
- Assess hemostasis, trends
- Observe for adverse reactions
- Assess therapeutic interventions
- Manage anesthetic depth
- Evaluate equipment function
What needs to be continually monitored during anesthesia?
Oxygenation, ventilation, circulation, temperature
What monitors must be used under minimal standards?
- Electrocardiogram (HR and rhythm)
- Blood Pressure
- Precordial stethoscope
- Pulse oximetry
- Oxygen analyzer
- End tidal carbon dioxide
What minimal monitoring information must be on graphic display?
- Electrocardiogram
- Blood Pressure
- Heart rate
- Ventilation status
- Oxygen saturation
What are three basic monitoring techniques?
- Inspection
- Auscultation
- Palpation
What are 5 considerations when choosing hemodynamic monitoring techniques?
- Indications/contraindications
- Risk/benefit
- Techniques/alternatives
- Complications
- Cost
Describe the purpose/use of a precordial stethoscope.
- Used for continual assessment of breath sounds and heart tones
- Esophageal use in intubated pts (only 28-30 cms into the esophagus)
- Very sensitive monitor for bronchospasm and changes in pediatric patients
When does a patient have to have ECG monitoring?
Continuously from the beginning of anesthesia until leaving anesthesia location
What is the purpose of ecg monitoring?
- Record electrical activity of the heart
- Detect arrhythmias
- Monitor heart rate
- Detect ischemia
- Detect electrolyte changes
- Monitor pacemaker function
Describe the difference between 3 lead and 5 lead ECGs.
3 Lead:
- Elecrodes RA, LA, LL
- Leads I,II, III
- 3 views of the heart
5 lead:
- Electrodes RA, LA, LL, RL and chest lead
- Leads I, II, III, aVR, aVL, aVF, V lead
- 7 views of heart
What should the gain of an ECG be set at?
Gain should be set at standardization
- 1 mV signal produces 10mm calibration pulse
- a 1 mm ST segment change is accurately assessed
What should the filtering capacity be set to on an ECG?
Filtering capactiy should be set to diagnostic mode.
-Filtering out the low end of the frequency bandwith can distort ST segment
What are the 5 principle indicators of acute ischemia on an ECG?
- ST segment elevation ≥ 1mm
- T wave inversion
- Development of Q waves
- ST segment depression, flat or downslope of ≥1mm
- Peaked T waves
What leads would you see changes in with posterior/inferior wall ischemia (right coronary artery)?
Leads II, III, AVF
What leads would you see changes in with lateral wall ischemia (circumflex branch of left coronary artery)?
Leads I, AVL, V5-6
What leads would you see changes in with anterior wall ischemia (left coronary artery)?
Leads I, AVL, V1-V4.
What leads would you see changes in with anterioseptal ischemia (left descending coronary artery).
Leads V1-V4
What do changes in systolic/diastolic blood pressure correlate with?
Changes in SBP correlate with changes in myocardial O2 requirements. Changes in DBP reflect coronary perfusion pressure
What changes occur to the pulse pressure and SBP as a pulse moves peripherally?
As a pulse moves peripherally wave reflection distorts the pressure waveform-exaggerated SBP and wider pulse pressure.
What are 4 ways to non-invasively measure blood pressure?
- Palpation-palpating the return of arterial pulse while on occuluded cuff is deflated
- underestimates systolic pressure, 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 stehoscope. Korotkoff sounds due to turbulent flow within an artery created by mechanical deformation from BP cuff.
- Permits estimation of SBP and DBP, unreliable in HTN patients (usually lower) - Oscillometry- senses oscillations/fluctuations in cuff pressure produced by arterial pulsations while deflating a BP cuff. The first oscillation correlates with SBP, maximum/peak oscillations occur at MAP, oscillations cease at DBP. This is how automated cuffs work.
Describe the sizing and positioning of a BP cuff.
- Bladder width 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
What can cause false high BP measurements with a BP cuff?
- Cuff too small
- Cuff too loose
- Extremity below level of heart
- Arterial stiffness- HTN, PVD
What can cause false low BP measurements with a BP cuff?
- Cuff too large
- Extremity above level of heart
- Poor tissure perfusion
- Too quick deflation
What are some complications associated with non-invasive blood pressure measurement?
- Edema of extremity
- Petechiae/bruising
- Ulnar neuropathy
- Interference of IV flow
- Altered timing of IV drug administration
- Pain
- Compartment syndrome
Describe invasive blood pressure measurement.
- Involves percutaneous insertion of a 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
- Small catheter
- Sites of insertion include radial, ulnar, brachial, femoral, dorsalis pedis, axillary
- Transducer system-continuous flush device. 1-3 ml/hr of NS prevents thrombus formation, allows rapid flushing
- 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
What are the indications for invasive blood pressure measurement?
- 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 pressure sampling
- Failure of indirect BP measurement
Describe leveling an A-line.
- Mid axillary line in supine patients (right atrium)
- Level of the ear (circle of willis) in sitting pts
What does the rate of upstroke indicate on an arterial waveform?
Contractility
What does the rate of downstroke indicate on an arterial waveform?
SVR
What is the effect of hypovolemia on the arterial waveform?
Exaggerated variations in size with respirations.