Venous / Arterial Compliance Ratio Calculation. Conflict of Interest

Transcription

1 Venous / Arterial Compliance Ratio Calculation Kirk H. Shelley, M.D., Ph.D. Professor of Anesthesiology Yale University STA 13 Conflict of Interest Twenty plus year history of research on this and related topics. Not a consultant, not in any speaker bureau, nor on any advisor boards. I do not like NDA / CDAs Have applied for patents on this and related technology. Scientific founder of a Yale start-up company to help bring new PPG technology to the marketplace. 1

2 Clinical Monitoring Essentials What do we understand about the physiology? What is our mental model? Can we monitor it? Biomedical engineering Does it alter therapy? Do we do something with this information? Does it change outcomes? Remarkably complex question Clinically Actionable Information Fluid status Early success with respiratory-induced variability Fluid infusion vs. Diuretics Vasculature tone What do we follow? BP? SVR? Vasoconstrictor vs. Vasodilator Cardiac function Adequacy of tissue perfusion on a global and regional level. Blood transfusion & Inotropic medications Rivers, E., B. Nguyen, et al. (1). "Early goal-directed therapy in the treatment of severe sepsis and septic shock." N Engl J Med 34(19): O'Connor, M. F. University of Chicago (9-11): Understanding Clinical Hemodynamics ASA Refresher Course 2

3 LED! PD! Hertzman, A.B. and C. Spielman, Observations on the finger volume pulse recorded photoelectrically. Am J Physiol, : p A Volume Signal!! Baseline vs. Amplitude Modula3on Baseline modula3on occurs before Amplitude modula3on 6 3

4 Real World Bleeding 12:4:1. AM LIVER TX BLEEDING 12_ 16_ PPG (AU) Baseline Modulation Pulse Amplitude remains constant : 46: 46: 46: LIVER TX BLEEDING 12_ 16_ 12::46.3 AM 6 PPG (AU) 4 2 Baseline and Amplitude Modulating : : 1: 1: Aymen Alian Yale University Two types of modulation Stroke Volume Variation (ΔPOP) AC Modulation Venous Blood Movement DC Modulation Combined Modulations Adam Shelley - Johns Hopkins 4

5 PPG = Arterial + Venous LIVER TX BLEEDING 12_ 16_ Arterial Pressure (mmhg) 12::46.3 AM PVP (mmhg) PPG (AU) : : 1: 1: Aymen Alian Yale University. Blood in Motion Oesophageal Pulse Oximeter. 4. 'IR AC' 'Red AC' V * Hz Venous modulation Arterial modulation. Resp Cardiac Frequency Pt 17: : - 6:4 mins : Spectrum (Amplitude Density) 9 x 8192 (4 Hz) Nov 7 St. Bartholomew's Hospital City University London, England Kirk Shelley Justin Phillips Richard Langford Prof Panayiotis Kyriacou

6 Potential to have information from both the pre-load and after-load side from the pulse oximeter waveform. Zac Walton Yale University Venous/Arterial Compliance Ra3o Compliance = volume /pressure Photoplethysmograph (PPG) modula3on is an uncalibrated measure of blood volume change. The arterial line (or just a BP cuff!) and peripheral IV allows one to measure pressure change. PPG modula3on at the respiratory frequency (.1 Hz.4 Hz) = change of venous blood volume PPG modula3on at the cardiac frequency (.8 Hz 2. Hz) = change of arterial blood volume 6

7 9.9 ratio=(1.26/.4) / (1.438/6.27) Effect of Phenylephrine Case 23_ shoulder_ 9 _ post_ induction_ waves_ compliance_ total_ power v 2 Complian... Finger PP... PVP (mm... Arterial P :3:8. AM Venous C Arterial C :4: 1:6: 1:8: 1:: 1:12: 1:14: 1:16: Aymen Alian Yale University 7

8 Shoulder Case Older patient with labile blood pressure Case 23_ shoulder_ 9 _ post_ induction_ waves_ compliance_ total_ power 12:6:. AM Arterial Pressure (m... PVP (mmhg) Finger PPG (AU) - Compliance ratio () Venous Compliance () Arterial Compliance () :: 1:: 1:: 1:: 1:: Effect of Phenylephrine on Arterial Compliance Pre-Drug Post-Drug The arterial compliance goes down (vessels get tighter) with phenylephrine. 8

9 3 Effect of Phenylephrine on Venous Compliance 3 2 Pre-Drug Post-Drug The venous compliance goes up (vessels get looser) with phenylephrine. Effect of Phenylephrine Median value of the effect of Phenylephrine on Compliance compliance Venous Compliance (V) Arterial Compliance (A) (V/A)Compliance ratio ratio * * * 12. Pre-Drug Post-Drug events So arteries get tighter, veins get looser therefore the vein/arterial compliance ratio goes up with phenylephrine 9

10 Effect of Fluid Boluses Scoliosis Case #_ 4_ 16_ 12_ Part 2 Scoliosis Case #_ 4_ 16_ 12_ Part 2 A. Line (m... 1:48:19.77 AM A. Line (... 2:3:6. AM PVP (mmh PVP (mm PPG (AU) 3 2 PPG (AU) 3 2 Venous co... 2 Venous c... 2 Arterial co Arterial c complianc... 1:48:3 1:49: 1:49:3 1:: 1::3 Before fluid bolus complian... 4: 2:4:3 2:: 2::3 2:6: 2:6:3 After fluid bolus Effect of 3cc Fluid Boluses on Venous Compliance Before fluid bolus After fluid bolus Venous Compliance drops (veins become tighter) with fluid boluses.

11 Effect of Fluid Bolus on Arterial Compliance Before fluid bolus After fluid bolus No significant change in arterial compliance with fluid boluses Effect of Fluid Boluses Median value of effect of fluid bolus on compliance Venous Compliance (V) Arterial Compliance (A) (V/A)Compliance ratio ratio Before fluid bolus After fluid bolus * * events So arteries stay the same, veins get tighter therefore the vein/ arterial compliance ratio goes down with fluid boluses. 11

12 Why use a ratio? Given the fact the PPG is uncalibrated the individual arterial and venous compliance measurement can only be followed as a trend monitor. The venous/arterial compliance ratio allows for the development of a threshold monitor with normal values and the potential to guide vasopressor therapy. Needed to move forward Examples over a wider range of interventions and conditions. Pharmaceutical NTG, Nitroprusside, Vasopressin, Epinephrine, etc Clinical Conditions Sepsis, CHF, Renal Failure Responder vs. Non-Responder type Studies Outcome studies that demonstrates that changes in therapy based upon this new measurement. Goal would be improved tissue perfusion What is a marker of that? PI, UO, GI function, venous sats? 12

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