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Hemodynamic Monitoring 2016Avoiding Occult hypoperfusion
Tom Ahrens, PhD RN FAAN
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NO! Physical Assessment is often inaccurate, slow to change and difficult to interpret 4
• Stroke volume falls• Heart rate compensates to keep cardiac output
normal– Many reasons for heart rate to increase
• Cardiac output falls• Heart rate compensation fails• Vasoconstriction (increase in SVR), BP remains
unchanged• Increased oxygen extraction of hemoglobin
• Peripheral initially (StO2)• Central later (ScvO2)
• Blood pressure, urine output change5
Signs of Hypoperfusion
LV dysfunction
Hypovolemia
Sepsis
Which signs are similar with all
three?
BP
HR
LOC
Urine output
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• Connors AF Jr, Dawson NV, Shaw PK, Montenegro HD, Nara AR, Martin L. Hemodynamic status in critically ill patients with and without acute heart disease. Chest. 1990 Nov;98(5):1200-6.
• Dawson NV, Connors AF Jr, Speroff T, Kemka A, Shaw P, Arkes HR. Hemodynamic assessment in managing the critically ill: is physician confidence warranted? Med Decis Making. 1993 Jul-Sep;13(3):258-66.
• Eisenberg PR, Jaffe AS, Schuster DP. Clinical evaluation compared to pulmonary artery catheterization in the hemodynamic assessment of critically ill patients. Crit Care Med. 1984 Jul;12(7):549-53.
• Iregui MG, Prentice D, Sherman G, Schallom L, Sona C, Kollef MH. Physicians' estimates of cardiac index and intravascular volume based on clinical assessment versus transesophageal Doppler measurements obtained by critical care nurses. Am J Crit Care. 2003 Jul;12(4):336-42.
• Neath SX, Lazio L, Guss DA. Utility of impedance cardiography to improve physician estimation of hemodynamic parameters in the emergency department. Congest Heart Fail. 2005 Jan-Feb;11(1):17-20.
• Staudinger T, Locker GJ, Laczika K, et al. Diagnostic validity of pulmonary artery catheterization for residents at an intensive care unit. J Trauma. 1998 May;44(5):902-6.
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• CVP and PAOP should never be used in isolation–Inconsistent in revealing information about
volume and flow• Flow and pressure do not always correlate
–Marik et al. Based on the results of our systematic review, we believe that CVP should no longer be routinely measured in the ICU, operating room, or emergency department.
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Marik P, Baram M, Vahid B. Does central venous pressure predict fluid responsiveness?A Systematic Review ofthe Literature and the Tale of Seven Mares. Chest 2008;134;172-178
Trends…..Trends…..BaselineBaseline
SV 22SV 22
HR 113HR 113
CO 2.5CO 2.5
FTc 288FTc 288
CVP 7CVP 7
S/P 5000 S/P 5000 mlsmls
7575
83 83
6.5 6.5
360 360
7 7
S/p 250 S/p 250 mlsmls LR LR
3333
99 99
3.2 3.2
310 310
7 7
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• Is BP is measured because it can be measured
• If BP increases, does blood flow increase?– think of use of levophed
• Blalock 1943, says:“It is well known by those interested in this “It is well known by those interested in this “It is well known by those interested in this “It is well known by those interested in this subject that the blood volume and cardiac subject that the blood volume and cardiac subject that the blood volume and cardiac subject that the blood volume and cardiac output are usually diminished in traumatic output are usually diminished in traumatic output are usually diminished in traumatic output are usually diminished in traumatic shock before the arterial blood pressure shock before the arterial blood pressure shock before the arterial blood pressure shock before the arterial blood pressure declines significantly”declines significantly”declines significantly”declines significantly”
Blalock A, (1943) Surgery 14: 487-508
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BP Measurement - Useful or Misleading?BP Measurement - Useful or Misleading?
Do they equal each other?
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• CO = Stroke volume x heart rate–decrease in SV causes increase in heart
rate–decrease in CO causes increase in SVR
• Compensatory changes keep the BP close to normal initially in shock states
• BP does not change until late due to these compensatory responses
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What is the Purpose of Blood Pressure?The role of the biventricular cardiovascular system
What is the Purpose of Blood Pressure?The role of the biventricular cardiovascular system
Systemic Values Pulmonic Values
LV 110/10 RV 25/0-5
Aorta 120/80 PA 25/10
Capillaries 30-50 Capillaries 12-17
RA 0-5 LA 8-12
Stroke Volume as an End point
Stroke volume normal valuesStroke volume variation
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• Chytra I, Pradl R, Bosman R, Pelnar P, Kasal, Zidkova A. Esophageal Doppler-guided fluid management decreases blood lactate levels in multiple-trauma patients: a randomized controlled trial. Critical Care 2007 Feb 22;11(1):1-9.
• Conway DH, Mayall R, Abdul-Latif MS, Gilligan S, Tackaberry C. Randomized controlled trial investigating the influence of intravenous fluid titration using esophageal Doppler monitoring during bowel surgery. Anesthesia 2002 Sept;57(9):845-849.
• Gan TJ, Soppitt A, Maroof M, El-Moalem H, Robertson K, Moretti E, Dwane P, Glass PS. Goal-directed intra-operative fluid administration reduces length of hospital stay after major surgery. Anesthesiology 2002;97:820-826.
• Mark JB, Steinbrook RA, Gugino LD, et al. Continuous noninvasive monitoring of cardiac output with esophageal Doppler during cardiac surgery. Anesth Anlg 1986;61:1013-1020.
• McKendry M, McGloin H, Saberi D, Caudwell L, Brady AR, Singer M. Randomized controlled trial assessing the impact of a nurse delivered, flow monitored protocol for optimization of circulatory status after cardiac surgery. BMJ 2004;329(7460):258 (31 July), doi:10.1136/bmj.38156.767118.7C.
• Mythen MG, Webb AR. Peri-operative plasma volume expansion reduces the incidence of gut mucosal hypoperfusion during cardiac surgery. Archives of Surgery 1995;130:423-429.
• Sinclair S, James S, Singer M. Intraoperative intravascular volume optimization and length of hospital stay after repair of proximal femoral fracture: randomized controlled trial. BMJ 1997 October 11;315:909-912.
• Valtier B, Cholley BP, Belot JP, Coussay JE, Mateo J, Payen DM. Noninvasive monitoring of cardiac output in critically ill patients using transesophageal Doppler. Am J Respir Crit Care Med. 1998;158:77-83.
• Venn R, Steele A, Richardson P, Poloniecki J, Grounds M, Newman P. Randomized controlled trial to investigate influence of the fluid challenge on duration of hospital stay and perioperative morbidity in patients with hip fractures. British Journal of Anesthesia 2002;88:65-71.
• Wakeling HG, McFall MR, Jenkins CS, Woods WGA, Miles WFA, Barclay GR, Fleming SC. Intraoperative esophageal Doppler guided fluid management shortens postoperative hospital stay after major bowel surgery. Br J Anaesth. 2005 Nov;95(5):634-42. 15
Evidence (8 RCTs) of Using SV as Evidence (8 RCTs) of Using SV as Evidence (8 RCTs) of Using SV as Evidence (8 RCTs) of Using SV as EndpointEndpointEndpointEndpoint
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SV Optimization for Fluid SV Optimization for Fluid SV Optimization for Fluid SV Optimization for Fluid AdministrationAdministrationAdministrationAdministration
Stop giving fluids Monitor SI as indicated
Give 200 ml of colloid Or 500 ml of crystalloid
If SV/SI or FTc is low
Is the heart Pumping enough
Blood?
YES(SI increased < 10%)
NO(SI increased > 10%)
If SV/SI decreased >10%
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Stop treatment Monitor SI as indicated
Give preload reducer, afterload reducer or inotrope
If SV/SI or PV is low
Is the heart Pumping enough
Blood?
YES(SI increased < 10%)
NO(SI increased > 10%)
If SV/SI decreased >10%
SV Optimization for Ht Failure SV Optimization for Ht Failure SV Optimization for Ht Failure SV Optimization for Ht Failure
SV as an End point
SV normal values
SV variation
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Moving Toward Blood Flow Moving Toward Blood Flow Moving Toward Blood Flow Moving Toward Blood Flow MeasurementMeasurementMeasurementMeasurement
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Determine success of fluid or inotropic therapy by The response in stroke volume/index and SvO2
Stroke Volume
End-Diastolic Volume
∆∆∆∆ < 10%
∆∆∆∆ > 10%
∆∆∆∆ 0%
Treatment Guidelines
Uses Ease of use Accuracy Professional Reimbursement
Doppler -USCOM
Anywhere Good Good -
Doppler (EDM) OR, ICU Excellent Excellent $$$
ECON OR, ICU Good Fair -
Bioimpedance Anywhere Good Fair $
Pulse contour(FloTrac, LiddCo, PICCO)
OR, ICU Difficult Fair -
NICO OR, ICU Difficult Fair -
PAC OR, ICU Difficult Good $$
Bioreactance OR, ICU Good Good $ 20
Methods of Measuring SVMethods of Measuring SVMethods of Measuring SVMethods of Measuring SV
Non invasive CO/SV measurement
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• All methods have strengths and limitations
• Many acute and critical care patients can have these techniques used
• All can be used within limitations
• Use oxygenation end points to validate information regarding blood flow
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Arguable – but the one with the most evidence is clear – esophageal Doppler
Which has the most potential application?Non invasive Doppler
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Which Technique is Best?Which Technique is Best?Which Technique is Best?Which Technique is Best?
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U.S. & U.K. Support at the U.S. & U.K. Support at the U.S. & U.K. Support at the U.S. & U.K. Support at the Federal LevelFederal LevelFederal LevelFederal Level
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Example of a real screenExample of a real screenExample of a real screenExample of a real screen
Stroke Volume Optimization is the Key
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Overview
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Interpreting Stroke VolumeInterpreting Stroke VolumeInterpreting Stroke VolumeInterpreting Stroke Volume
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• SV: How much blood is pumped with each beatNormal: 50-120 ml/beat
• SI: How much referenced against body sizeNormal: 25-50 ml/m2
• SD: The distance that blood flows in a specifictime period (This is the most accurate).
Normal: > 10; Hypovolemia: <10
*Normals are just reference points. The real test is whether or not they change if fluid is given.
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FTc: Flow Time correctedThe time of systolic flow corrected to heart rate.
PV: Peak VelocityThe velocity of the blood measured at the peak of systole.
20 yrs: 90 - 120 cm/sec50 yrs: 60 - 90 cm/sec70 yrs: 50 - 80 cm/sec
330 - 360 milliseconds
Normal Ranges
NOTE: Normal Ranges should not be confused with a Physiological Target.
Esophageal Doppler Variables
• After induction, FTc of 323ms, (low) indicated possible hypovolemia.
• SV of 77 ml was reasonable; however, HR of 60 gives a cardiac index (CI) of 2.3 l/m/m2.
• 200ml of colloid was given.
• SV increased >10%, suggesting more colloids be given to optimize the intravascular volume.
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• After 2nd bolus, SV increased by 14 ml (19%) and FTc also increased.
• CI increased from 2.3 to 2.7 l/min/m2
• Indicated more fluid could be given to optimize SV.
• More colloid given in accordance with the SV optimization algorithm until SV increases were less than 10%.
Who is being harmed by our current practices?
We must have a sense of urgency32
Seeking a Direct Measure of Tissue Oxygenation
• Blood draw
• Lab or bedside analysis
• Normal lactate – 1-2 mmol
• pH – normal 7.35-7.45
• If lactate > 4 mmol and pH is less than 7.30, consider tissue hypoxia
• CAUTION: Lactate can increase for reasons other than hypoxia
• Reflects perfusion status where oxygen is delivered to tissue
• If StO2 is < 75% or dropping, consider inadequate tissue perfusion
• Potentially earliest indicator of a threat to tissue oxygenation
• CAUTION: May not be the same as ScvO2 or SvO2
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Lactate as Indicator of Hypoxia
Chemical energy(high-energyElectrons)
GLYCOLYSIS
Glucose Pyruvicacid
Chemical Energy
KREBSCYCLE
Electron transport chain and oxidativephosphorylation
Mitochondrion
ATPsATPs
Cristae
ATPs
Lactate N= 529
< 2 (N=219) 2-4 (N=177) > 4 (N = 104)
SBP > 90 158/219 (72%)116/177 (65%)
64/104 (62%)
SBP < 9061/219 (28%) 61/177 (34%)
40/104 (38%)
Lactate Levels and SBP
No Ventilation CPR
ABC’s or CAB’s
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The relationship between hemodynamics and oxygenation
The relationship between hemodynamics and oxygenation
The role of mixed venous oxyhemoglobin (SvO2)
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Microvascular Blood Flow Is Impaired with normal or
elevated macro hemodynamics (SV, CO)
Venous blood
Arterial bloodSO2 - .98
SO2 - .94
SO2 - .65
SO2 - .86
SO2 - .65
SO2 - .83
SO2 - .65
StO2 Monitoring
Near Infra-Red Spectrometry (NIRS)
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• Hemodynamic monitoring should focus on stroke volume optimization
• Most patients can have hemodynamic monitoring
• Tissue oxygenation should be combined with macro hemodynamic measurements
• The application of hemodynamic monitoring is greater than ever
Summary