Making the Case For Less Invasive Flow Based Parameters: APCO + SVV. Patricia A. Meehan, RN, MS, CCRN (a) Education Consultant Edwards Lifesciences

Transcription

1 Making the Case For Less Invasive Flow Based Parameters: APCO + SVV Patricia A. Meehan, RN, MS, CCRN (a) Education Consultant Edwards Lifesciences

2 A New Gold Standard?

3 How does the system work? Sensor measures the pressure variation from the existing arterial line. Pulse pressure proportional to SV. Monitor uses Sensor values to continuously compute SV. Input age, gender, ht, and wt to determine patient-specific vascular compliance. Dynamic changes in the peripheral resistance and vascular tone, which affect pulse pressure, are compensated for. Monitor displays CO on a continuous basis (every 20 sec) by multiplying the pulse rate and computed SV.

4 Technology Description SBP PP SV SD SV DBP PP (SBP DBP) is proportional to SV. (Inversely proportional to aortic compliance) Full arterial pulse waveform is assessed at 100 Hz. Variability (SD) of the arterial pressure is made over a 20 second window. SD is proportional to SV. SV x PR = CO

5 What about vascular changes? Effect of altered vessel compliance and changing resistance: Software compensates for physiologic effects on arterial pressure: Effect of large vessel compliance Age, gender, height, weight Effect of peripheral resistance Assessment of waveform elements associated with vascular changes

6 Effect of peripheral resistance The algorithm looks for characteristic changes in arterial pressure that affect flow Those changes are included in the calculation of SV Quick rise in pressure - Increased resistance Increase MAP - Increased resistance Dramatic increase/decrease in pressure within same time altered resistance

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8 Concerns and Potential Limitations 1. Factors affecting arterial pressure monitoring Prime tubing - Components Proper leveling Proper zeroing Square Wave Test 2. Causes of irregular heart rate 3. Concerns with additional calibration

9 A clinical question: Can the head of bed be raised? Angles YES, BUT... must ensure that the transducer air fluid interface is raised as well!

10 Pressure Tracing Showing Erroneous Values due to Bed Height Movements Bed Raised Bed Raised Bed Raised Bed Lowered Bed Lowered

11 Arterial Pressure Based Technologies that use the arterial pressure to determine cardiac output can be affected by the quality of the arterial pressure tracing. Note the impact of an overdamped tracing on the LiDCO cardiac output value. Jansen & van den Berg 2005 Technologies

12 Basic parameters: Are they enough? Mr. B is a 58 y/o male. Post-op AAA monitored in the PACU with noninvasive technology. Is Mr. B stable?

13 Gave Volume 1 Mr. B is given a 500 ml fluid bolus. The MAP increased slightly. HR decreased slightly. Is this sufficient?

14 Gave Volume 2 Mr. B is given another 250 ml bolus of fluid. The MAP increased slightly. HR decreased slightly. Does the blood pressure reflect flow?

15 Does Pressure = Flow? Headley 2006 Critical Care Nurse Clinics of North America

16 Assumptions: Blood pressure reflects flow MAP = CO If BP goes up then CO goes up.. If CO is down then BP is down Assumption P = F is really a MISCONCEPTION

17 What Makes an Arterial Pulse? Arterial SV SBP PP SV Cardiac Output MAP Arterial Tone: Compliance Resistance DBP JMHeadley 2005 Arterial SVR

18 Does Pressure = Flow? Headley 2006 Critical Care Nurse Clinics of North America

19 MAP: slow to respond, does not tell the full story.. It should be recognized that systemic hypo-perfusion usually precedes hypotension, especially in patients with sepsis MAP ~ SVR X CO Rackow, JAMA 1991 P = R x F (Schwaitzberg, J Ped Surg, 1988)

20 Added CVP Mr. B now has a central line placed. CVP is within normal range. Do Nothing? Add Cardiac Output? Did this add more information to the case? Give Volume? Add SVV?

21 Preload Responsiveness: Which test is best? A. Traditional clinical markers of hypovolemia Low Urine Output - limited with AKI and CRF Dry mucous membranes B. CVP and PAWP C. Response of BP to a fluid bolus D. SVV and PPV

22 P V Preload indices such as CVP, RAP, PAOP, and LVEDP are poor predictors of preload status and volume responsiveness. Altered ventricular compliance affects the P/V relationship. These are also known as static indices as they do not predict the patient s response to fluid.

23 Kumar et al. CCM 2004 CVP and PAOP: Poor Predictors of Fluid Status Pressure based indices did not correlate to volume or change in stroke volume after a fluid bolus. Pre-fluid bolus Post fluid bolus Pre-fluid bolus Post fluid bolus

24 Added Cardiac Output The decision was made to add APCO to assess flow. An arterial line was inserted and attached to a FloTrac sensor. Did this add more information to the case?

25 Added Cardiac Output Volume was given CO increased but only by 10% Would additional parameters provide needed information in a more timely manner?

26 Pulsus Paradoxus: The Origin of SVV Pulsus Paradoxus is the origin of SVV value. Occurs with spontaneously breathing patients. Reverse Pulsus Paradoxus Occurs during positive pressure ventilation. Clinical use of this phenomenon remains marginal. Michard Anesthesiology 2005

27 Added SVV The stroke volume variation is abnormally elevated. Normal is 10 15%. This indicates that the patient will be responsive to fluid Did this add more information to the case?

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29 Kungys, Rose, Fleming 2009 Basic hemodynamic variables such as HR and arterial blood pressure may not have the sensitivity required for optimal care.

30 Kungys, Rose, Fleming 2009 Optimization of intravascular volume based on real-time changes in SVV may be an appropriate strategy, especially for patients in whom tighter control of fluid replacement is beneficial.

31 Right monitor for the Right Patient An improved understanding of these emerging technologies will assist the intensivist in applying the appropriate device to his or her particular setting. Minimally invasive hemodynamic monitoring for the intensivist: Current and emerging technologies Chaney & Derdak Crit Care Med 2002

32 Making the Case For Less Invasive Flow Based Parameters: APCO +SVV CAUTION: Federal (United States) law restricts this device to sale by or on the order of a physician. See instructions for use for full prescribing information, including indications, contraindications, warnings, precautions and adverse events. Patricia A. Meehan is a paid consultant of Edwards Lifesciences. Any quotes used in this material are taken from independent third-party publications and are not intended to imply that such third party received or endorsed any of the products of Edwards Lifesciences. As a member of the Advanced Medical Technology Association ("AdvaMed"), Edwards Lifesciences strictly adheres to the requirements of the AdvaMed Code of Ethics regarding interactions with health care professionals. Edwards Lifesciences wishes to disclose that all speakers, instructors and panel members will receive compensation and reimbursement of reasonable travel expenses from Edwards Lifesciences for their services in full compliance with all applicable laws, rules and regulations, including the AdvaMed Code of Ethics. Edwards is a trademark of Edwards Lifesciences Corporation. Edwards Lifesciences, and the stylized E logo, the FloTrac and Vigileo are trademarks of Edwards Lifesciences Corporation and are registered in the United States Patent and Trademark Office Edwards Lifesciences. All rights reserved. AR06143

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