ESTIMATION OF STROKE VOLUME BY NON-INVASIVE BLOOD PRESSURE MONITORING IN HUMAN CENTRIFUGE

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1 84TH ASMA ANNUAL SCIENTIFIC MEETING CHICAGO - MAY 12-16, 213 ESTIMATION OF STROKE VOLUME BY NON-INVASIVE BLOOD PRESSURE MONITORING IN HUMAN CENTRIFUGE PROGRAM ID NUMBER 445 MANEN O, DUSSAULT C, SAUVET F, BISCONTE S, HORNEZ A-P, MARTEL V, PERRIER E, MONTMERLE S Aeromedical Centre, Percy Military Hospital, Clamart, France Military Institute of Biomedical Research, Brétigny/Orge, France

2 Disclosure Information MANEN Olivier 84TH ASMA ANNUAL SCIENTIFIC MEETING CHICAGO - MAY 12-16, 213 I have no financial relationships to disclose I will not discuss off-label use I will discuss the following investigational use in my presentation : Portapres, FMV BV

3 INTRODUCTION / BACKGROUND Cardiac Output (CO) measurement : intermittent techniques ++ No validated techniques for continuous CO during extreme conditions Algorithms to estimate the Stroke Volume (SV) from the Arterial Blood Pressure (ABP) waveform : Initially based on central ABP Clinical validation with radial ABP vs thermodilution Accuracy with non-invasive ABP : matter of concern Remmen JJ. Clin Sci (Lond) 22; Sugawara J. Acta Physiol Scand 23; Lu Z. J Appl Physiol 26; Truijen J. J Clin Monit Comput 212; Van Lieshout JJ. Eur J Appl Physiol 23 Pitt MS. Clin Sci (Lond) 24 Bogert LW. Anaesthesia 21 Van Der Spoel AG. J Clin Anesth 212

4 Estimator Mean Pressure Windkessel Systolic Area CO = k. below P mean P pulse. HR A sys. HR Warner Time Correction ( 1 + T sys / T dias ) A sys. HR Liljestrand & Zander ( P pulse / ( P sys + P dias )). HR Herd ( P mean P dias ). HR Corrected Impedance variant of systolic area Nonlinear compliance complex formula RMS Simplified form of Exponential best fit (( P(t) P mean )²). HR fit curve to diastolic decay 3-element model variant of non linear, time-varying model RMS, root-mean-square. HR, heart rate. Asys, area under systolic region of ABP. Tsys, Tdias durations of systole, diastole. Sun JX. Crit Care Med 29

5 OBJECTIVES Main objective To evaluate the accuracy of finger ABP waveform to estimate SV, with 3 different algorithms, in comparison to echocardiography, before and after exposure to +Gz accelerations in human centrifuge Second objective Estimator Best algorithm? Windkessel CO = k. below P pulse. HR A sys. HR Systolic Area Liljestrand & Zander ( P pulse / ( P sys + P dias )). HR Protocol approved by the Ethics Committee of Ile-de-France III, 21 Military Institute of Biomedical Research (IRBA), Department of Operational Environments,

6 METHODS Population 1 military male volunteers (French Air Force) Young age : mean ± SD, 3 ± 2 y Strong constitution : body surface mean ± SD, 1.95 ±.2 m² Non smoker No cardio-pulmonary disease Good cardiac echogenicity Inclusion examination (physical exam, rest ECG, echocardiography) Written informed consent

7 Materials Human centrifuge Echocardiograph Anti-G suit Finger Portapres system

8 Protocol Pre-run stages Location Medical room Stage Action Runs Centrifuge gondola 1 1 min rest 2 Echo 1 1 min Rest Echo 2 ECHO_1 Medical room Warm-up and Type 1 profile Echo 3 Echo 4 BP BP SV echo ABP waveform 3 s 3 SV Portapres File Post-run stages ECHO_2 T= 6 Rest Echo 5 T= min ECHO_3 ECHO_4

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10 Centrifuge runs + Gz Time (seconds) 12 + Gz 15 s min 15 s 15 s 2 min 2 min 15 s 2 min Time (minutes) 4 8

11 RESULTS Quality of BP signal with the Portapres system Unexploitable signal in 16% of ABP segments Comparison of the averages 13 * SV (%) 115 SV echo SV Liljestrand 1 SV systolic area SV Windkessel 85 7 echo 1 1 echo 2 2 echo 3 3 Ultrasound periods echo 4 4 echo 5 5

12 Reproducibility with Bland and Altman method Liljestrand Systolic area (SV echo + SV Liljestrand) / 2 (ml) (SV echo + SV systolic area) / 2 (ml) High «95% limits of agreement» Windkessel SV Windkessel - SV echo (ml) SV systolic area - SV echo (ml) SV Liljestrand - SV echo (ml) (SV echo + SV Windkessel) / 2 (ml) 12

13 1 Linear regression analysis Liljestrand SV Liljestrand (ml) 12 Y =,55 X + 45,188 R2 =, SV echo (ml) Systolic area SV systolic area (m l) 1 12 Y =,585 X + 44,527 R2 =, SV echo (ml) 1 SV Windkessel (ml) 12 Y =,51 X + 5,578 R2 =, Windkessel SV echo (ml)

14 During the «warm-up» run Blood Pressure Anti-G suit Pressure G-level Blood Pressure Heart Rate Stroke Volume Cardiac Output

15 During the «type 1 profile» run Blood Pressure Anti-G suit Pressure G-level Blood Pressure Heart Rate Stroke Volume Cardiac Output

16 DISCUSSION Main results SV by finger ABP waveform (Portapres) close to SV by ultrasound Changes in the same direction Calibration necessary A random error : difficult calibration to obtain absolute SV monitoring of relative SV ++ Systolic area method ++ (best reproducibility)

17 DISCUSSION Review of the methods BP by finger photoplethysmography? Polito MD. Blood Press Monit 27 Nitzan M. Biomed Eng Online 29 An accurate method but ideal conditions : temperature > 22 C, hand covered, to move fingers Echocardiography as a reference method? Perfectible vs RMI / thermodilution Limits of the study Moderate G-levels No reference method during centrifuge runs Martins S. Rev Port Cardiol 2 Galderisi M. Eur J Echocardiogr 211 Trinkmann F. Clin Cardiol 21

18 CONCLUSION Continuous monitoring of relative SV / CO : aeronautical applications Aeromedical training of fighter pilots / navigators in human centrifuge MEDEVAC Futures prospects Protocols without anti-g suit or with +Gz > 4 G Transthoracic bioreactance vs finger ABP waveform, in comparison to ultrasound

19 Thank you for your attention

20 Collection and analysis of data Echocardiography ABP waveform Acqknowledge MyLab Desk MatLab Excel SV echo Calibration with echo 1 Exploitable? 3 s? SV waveform Relative SV Absolute SV Statistical analysis (3 steps) Averages Bland and Altman Linear regression