Monitoring the Cardiovascular Patient Flashcards
What is one of the primary responsibilities of an anesthesiologist ?
Act as a guardian for the anesthetized patient ?
Review slide -4
What is the definition of monitoring ?
Continuous or repeated observation + vigilance in order to maintain homeostasis
List the 4 ASA standards of monitoring
I. Qualified personnel
II.Oxygenation: SaO2, FiO2
III. Ventilation: ETCO2, stethoscope, disconnect alam
IV. Circulation: BP, pulse, ECG
**Other monitors: Temp Peak airway pressure, Vt, ABG
What are modalities in the OR?
- Arterial Line
- Systolic Pressure Variation
- CVP
- PAC
- Cardiac Output
- Mixed Venous O2
What are the five indications for an arterial line?
1-Rapid moment to moment BP changes
2- Frequent blood sampling
3- Circulatory therapies: bypass, IABP, vasoactive drugs, deliberate hypotension
4- Failure of indirect BP: Burns, morbid obesity
5- Pulse Contour Analysis, SPV, SV
What steps do we need order to place a radial artery catheter?
Good collateral circulation
*Allen’s test
Uncommon, however what complications can we see with a radial artery line placement that are not?
- Vasospastic disease
- Prolonged shock
- High dose vasopressors
- Prolonged Cannulation
What are alternative arterial line sites ?
1-Brachial
—use a longer catheter to traverse elbow joint
–postop keep arm extended
–collateral circulation not as good as hand
2-Femoral
–use guide-wire technique
–puncture femoral artery below inguinal ligament ( easier to compress if required)
How do we calculate systolic pressure variation(SPV)?
Difference between maximal + minima values of systolic BP during PPV
-Normal ~ 5 mmHg due to decrease venous return
What SPV value do we use to predict hypovolemia?
SPV >15mmHg
or down > 15mmHg
What does PulseCO SPV + SV do for us as providers?
1-Predicts SV increase in response to volume are cardiac surgery and in the ICU
2- Similar estimates of preload v. echo during hemorrhage
3-Helpful in dx of hypovolemia after blast injury
4- Limitations: AI, arrythmias,
*Required mechanical ventilation
What are the seven indication of central venous line?
1-CVP monitoring
2- Advanced CV disease + major operation
3- Secure vascular access for drugs: TLC
4- Secure access for fluids:introducer sheath
5- Aspiration of entrained air: sitting craniotomies
6- Inadequate peripheral IV access
7- Pacer, Stanz Ganz
What are the steps for a central venous line placement in the right IJ?
A. IJ vein lies in grove between sternal and clavicular heads of sternocleidomastoid muscle
B. IJ vein is lateral + slightly anterior to carotid
C.Aseptic technique, head down
D. Insert needle towards ipsilateral nipple
E. Seldinger method: 22G finder, 18G needle, guidewire, scalpel blade, + catheter
F. Observe ECG, maintain control of guidewire
G. US guidance, CXR post insertion
What are the advantages to a RIJ central line placement?
- Consistent, predictable anatomic location
- Readily identifiable landmarks
- Short straight course to SVC
- Easy intro access for anesthesiologist at patients head
- High success rate , 90-99%
What are the alternate sites to central line placement?
- Subclavian
- -Easier to insert vs IJ if in C-spine precautions
- -Better patient comfort vs IJ
- -Risk pneumo- 2%
- External Jugular
- -easy to cannulate if visible, no risk of pneuno
- -20% cannot access central circulation
- Double Cannulation of the same RIJ
- Serious complications: vein avulsion, catheter entanglement, catheter fracture
What does CVP monitoring provide for us?
A-Reflects pressure at junction of vena cava+ RA B-CVP is driving force for filing RA + RV C- CVP provides estimate of --intravascular blood volume --RV preload D-Trending CVP is useful E. Measure at END- EXPIRATION F.Zero at mid axillary line
What do pulmonary catheters allow ?
- Allows for accurate bedside measurement of important clinical variables: CO, PAP, PCWP, CVP to estimate LV filling volume + guide fluid/ vasoactive drug therapy
- Discloses pertinent CV data that cannot be accurately predicted from standard signs symptoms
PA waveform pressures?
Slide 26
What are the indications for a PAC by the ASA task force?
- High risk patient with severe cardiopulmonary disease
- Intended surgery places patient at risk because of magnitude or event of operation
- Practice setting suitable for PAC monitoring: MD familiarity, ICU, nursing
- PAC education project
What are PAC outcomes?
- Early use of PAC to optimize volume status, and tissue perfusion may be beneficial
- PAC is ONLY a monitor, it cannot improve outcome if disease has progressed too far, or if intervention based on PAC is unsuccessful or detrimental
- Many confounding factors: learning’s bias, skill knowledge, usage patterns, medical v surgical illness
What are pulmonary artery complications?
- Minor 50% eg: arrhythmias
- Transient RBBB- 0.9-5%
- -external pacer if pre-existing LBBB
- Misinformation
- Serious 0.1-0.5% : knotting , pulmonary infarction, PA rupture ( e.g. over wedge) ,endocarditis, structural heart damage
- Death 0.016%
Problems Estimating LV Preload ?
Review Slide 31
Cardiac output is an important feature of PAC, what does it allow calculation of ?
-DO2
How do you obtain CO on a PAC?
Thermodilution: inject fixed volume, 10 ml ( of room temp or iced D5W ) into CVP port at end-expiration+ measure resulting change in blood temp at distal thermistor
T/F: CO is directly proportional to area under the curve?
FALSE
Inversely proportional
What are the technical problems with CO on a PAC?
1- Variations in respiration
–use average of 3 measures
2- Blood clot over thermistor tip inaccurate temp
3- Shunts: LV + RV outputs unequal , CO invalid
4- TR: recirculation of thermal signal, CO invalid
5- Computation constants
–varies for each PAC, check package insert + manually enter
Mixed Venous Oximetry - is O2 sat, VO2 + Hgb remain constant, SvO2 is ?
An indicator of CO
-Can be measured using oximetric Swan or CVP, or send blood gas from PA/ CVP
What is normal SvO2?
~ 65%
60-75
What does it mean if your SvO2 is >75%?
- Wedged PAC: reflects LAP saturation
- Low VO2: hypothermia, GA, NMB
- Unable to extract O2: carbon monoxide
- High CO: sepsis, burns, L to R shunt, AV fistulas
What could a low SvO2 [<60%] mean?
- decreased CO: MI, CHF, hypovolemia
- low hgb: bleeding, shock
- decreased SaO2: hypoxia, resp distress
- increased VO2: fever, agitation, thyrotoxic, shivering
The factional area of change of the left ventricular cavity can be used as an index for what?
Global systolic function
What is the formula for fractional area of change?
FAC= (LVAd - LVAs)/ LVAd
Or
FAC = (EDA - ESA)/ EDA * 100
What is a normal range for FAC?
35-65%
Where is the made for FAC and what is it calculating?
The measure is made at the mid-papillary level by calculating the cross-sectional area of the LV during systole and diastole
What does it mean is you have an elevated SvO2? ( >75)
- Wedged PAC: reflects LAP saturation ( it is too far)
- Low VO2 state : hypothermia, general anesthesia , NMB
- Unable to extract O2: Carbon monoxide poisoning
- High cardiac output “ sepsis, burns, L –> R shunt, AV fistulas
What conditions would cause a low SvO2? (< 60%)
-decrease of the following
-CO: MI, CHF, hypovolemia
-Hgb : bleeding, shock
-SaO2 : hypoxia, respiratory distress
Increase in :
-VO2: fever, agitation, thyrotoxic shivering
Review TEE
Slide- 37
