Novel hemodynamic monitoring tool for major surgery and ICU patients. With minimally invasive doppler probe insertable through regular central line, Nilus is adding right side perspective back into hemodynamic monitoring.

1. Minimally invasive Doppler-based measurement of blood
velocity in superior vena cava - a new tool for detection of
early hypovolemia and fluid responsiveness and cardiac
output trending assessment
Tomas Kovarnik, MD, PhD.
Charles University Hospital, Prague, Czech Republic

2. Conflict of interest
• I, Tomas Kovarnik, have no conflict of interest

3. Challenges of volume therapy in
critically ill patients
• Hypovolemia is not rare in ICU and frequently is not
properly recognized
• Hypovolemia is treated by either vasopressors (
which increases afterload) or volume
• Volume overload in ICU worsens patients prognosis
and prolong time spent in ICU
• Accurate assessment of volume status is an essential
part of a treatment (not only) in ICU

4. Challenges of hemodynamic monitoring in
critically ill patients
• Classical Swan-Ganz catheter
– Invasive, increase risk for infection, high variability of CO in critically ill
patients
– Stable parameters (CVP, PAP, PCw pressures do not correlate well with
hemodynamic status a do not predict reaction to volume therapy)
• Pulse pressure variation
– Limited marker for right side hemodynamics
• Ultrasonographic measurement of flow in superior / inferior
vena cava
– Need experienced echocardiographers
– Cannot be continuous
– BUT: well related to right side hemodynamic, able to predict response
to volume therapy

5. Pulse Doppler of the SVC flow velocity was measured by Combowire (Volcano comp.) and
displayed on the console, which automatically detected and plotted the envelope of the
SVC flow velocity pattern. SVC flow measurement was respiratory and ECG gated. In 20 sec
long intervals we have analyzed flow variations during each individual respiratory cycle.
Minimal flow occurred during inspiration, maximal flow was recorded in
expiration. Doppler envelope data were continuously recorded with a custom PC-based
application specifically designed for the purposes of this trial.

6. Animal study protocol (10 pigs)
bleeding & volume substitution & volume overload
- Bleeding through was 6 F sheath introduced to the femoral artery
- Bleeding period was 10% of estimated blood volume (EBV), calculated
as 65 ml/kg and five times 5% of EBV during10 minutes each
- Two steps of 500 ml blood return (each during 30 minutes) separated by
10 minutes steady states.
- Saline 1 000 ml/30min two times was given separated by 10 minutes of
steady state after reinfusion of blood.

7. Venous Return Variation index (VRVi)
• New index of fluid responsiveness
• calculated as: VRV= (VTImax- VTImin) / (VTImax+VTImin)/2
• 43 individual measurement of VRV in confirmed volemia status events

8. SVC flow
monitoring
with
ComboMap
First version of
interphase and
analyzer

10. Correlation of VTImin with static markers of
hypovolemia.
Values are normalized to 100 points at the baseline
Comparison of cardiac output measurement
Doppler based vs. continuous pulmonary artery thermodilution
r = 0.95
Doppler-based indices vs. standard
measurements
30
50
70
90
110
130
150
170
190
210
1 2 3 4 5 6 7 8 9 10 11 12 13
EDP
PCWP
CVP
VTImin
VRV
PCWP 0.98
EDP 0.89
CVP 0.97
VRV index

11. Normal SVC flow pattern

12. Limitation of PPV during noradrenalin infusion
Case description: young patient with cerebral oedema with therapeutic hypovolemia
and noradrenalin infusion for keeping systemic blood pressure. Notice low PPV and
extreme elevation of VRV index. Significant low volume status would not be recognized
just based on PPV tracing.

13. Normal RV function
and non-elevated RA
pressure
S/D 1-2
sensitivity 86%,
specificity 78%
Reduction of RV
function with normal
RA pressure
S/D > 2
Sensitivity 69%,
specificity 81%
Reduction of RV
function with
elevated RA
pressure
S/D < 1
Sensitivity 52%,
specificity 95%

14. The spectra of SVC in the respiratory cycle in
patients with right heart failure
The spectra of SVC of healthy subjects in
the respiratory cycle

15. Right heart failure with tricuspid regurgitation
Dominant diastolic flow
Significant retrograde systolic flow

16. Description of first cases from clinical
practice
Abbreviations
RHD: right heart disease, TR: tricuspid regurgitation, PAH: pulmonary artery
hypertension, AoCo: aorto-coronary bypass

17. Summary
• Continuous measuring of SVC flow is safe, feasible and user-friendly
• Parameters of SVC flow closely correlate with traditional
hemodynamic parameters
• VRV has the steepest slope of increase and decrease and highest
change from basal level compared to traditional markers of volemia
and can predict reaction to volume challenge
• VRV better correlated with changes of volume status than PPV
• SVC Doppler flow closely followed changes of cardiac output
measured by thermodilution
• Parameters of SVC flow are suitable for continuous monitoring of
volume status during bleeding and volume supplementation
• S/D ratio from SVC is a sensitive marker for right heart dysfunction
and elevation of right atrium pressure
• Future directions: prediction of fluid responsiveness during
spontaneous breathing and cardiac arrhythmias
contact: tomas.kovarnik@vfn.cz