New techniques for monitoring of
dialysis patients
Jan Sternby
Gambro Research
© 2013, Gambro
1
Dialysis patients worldwide 2000-2010
2500
1 000 patients
2000
RoW
+ 156%
RoW
Japan
+ 47%
Japan
USA
+ 50%
Europe
+ 51%
1500
1000
500
0
USA
Europe
2000
2010
Gambro Market Information System 2012
© 2013, Gambro
2
Major drivers in the dialysis world today?
♦cost
- dialysis care takes up an unproportional part
of shrinking healthcare budgets
♦capacity
- increasing number of patients need dialysis
due to demographic changes and developing
economies
♦outcome
- high mortality, similar to some forms of cancer,
small improvement over past 25 year in spite of
significant technological and pharmaceutical
development
© 2013, Gambro
3
Cost efficient possibilities
Use already existing sensors for new tasks
♦Pressure transducers in blood line
♦Conductivity cell (after dialyzer)
♦Temperature sensors in fluid line
♦ .....
© 2013, Gambro
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With pressure transducers in blood line
♦Supervision of venous needle
♦Start up determination
♦Detection of reversed needles
Technical
Applications
♦Heart status monitoring
♦ heart rythm & heart rate variability
♦ ectopic beats & arrhythmia detection
♦Breathing monitoring
♦ Monitoring of sleep apnea in home patients
Medical
Applications
♦ Venous needle monitoring by breathing
♦Hypotension prediction
♦Cardiac output and access flow monitoring
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With conductivity cell after dialyzer
♦Clearance (dialysis efficiency)
♦Dialysis dose (Kt, Kt/V)
♦Recirculation
♦Plasma conductivity (~plasma sodium)
♦Access flow rate
♦Detect reversed needles
♦Cardiac output
© 2013, Gambro
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Why measure cardiac output
♦Dialysis patients have a high frequency of
cardiovascular problems (and mortality)
♦CO one important parameter in assessment of
cardiovascular status
♦No easy method exists to measure CO
♦Access blood flow directly related to CO
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Cardiac Output principle
QA
CO
AUCd
Qb
K
AUCd
K
=
M
CO
Dose=M
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Outlet conductivity after Sodium pulse
Outlet conductivity (mS/cm)
14.8
14.6
14.4
14.2
14
13.8
0
50
100
150
minutes
200
250
© 2013, Gambro
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Outlet conductivity after Sodium pulse
Outlet conductivity (mS/cm)
14.8
14.6
14.4
Outlet conductivity pulse
14.2
mS/cm
14
13.8
0
50
100
150
minutes
200
250
14.1
14.0
70
72
74
76
Time (min)
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Extraction of pulse
Post dialyzer conductivity (mS/cm)
14.3
14.25
14.2
14.15
56
58
60
62
64
66
68
Time (minutes)
© 2013, Gambro
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Extracted and filtered pulse
Post dialyzer conductivity (mS/cm)
14.3
14.25
14.2
14.15
56
58
60
62
Time (minutes)
64
66
68
© 2013, Gambro
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Cardiac Output comparison
Conductivity method vs Transonic
9
8
7
6
5
Cond1
4
Cond2
3
2
1
0
0
2
4
6
8
10
Cardiac output from Transonic (L/min)
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Cardiac Output, summary
♦No disposable required
♦Manual infusion of 2 ml NaCl
♦All calculations and timing instructions can be done
automatically by machine
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With pressure transducers in blood line
♦Supervision of venous needle
♦Start up determination
♦Detection of reversed needles
Technical
Applications
♦Heart status monitoring
♦ heart rythm & heart rate variability
♦ ectopic beats & arrhythmia detection
♦Breathing monitoring
♦ Monitoring of sleep apnea in home patients
Medical
Applications
♦ Venous needle monitoring by breathing
♦Hypotension prediction
♦Cardiac output and access flow monitoring
© 2013, Gambro
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VNM - Problem
Blood loss during extra-corporeal blood circulation
♦ Major causes
♦Venous needle drop-out
♦Needle connector fault
♦ Severity
♦Lethal blood loss within
3 to 12 minutes at full flow
♦ Prevalence
Venous needle dislodgement incident
discovered after ~20s,
blood flow 300 ml/min
♦Incidence rate
1/ 5 000 – 1/ 50 000
© 2013, Gambro
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Venous Pressure Monitoring (VPM)
- the conventional method
♦Venous needle dislodgement may
cause a pressure drop that triggers
an alarm and the blood pump stops
Pressure sensor
(venous)
Pro’s & Con’s
+ Low cost
+ No disposables
VP
Venous needle
- Many false alarms
Blood
line
- Alarm limits often set too wide
=> most patients are not
supervised!
- Cannot ensure detection of
needle disconnected under
blanket…
Fistula pressure
Fistula
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Improved Venous Pressure Monitoring
Techniques
• Suppressing pump pressure variation
• Detection based on both arterial and
venous pressure
Pump
variation
100
+
+
+
+
Narrower alarm limits(~15 mmHg)
Less false alarms
Low cost
No disposables
Pressure vs time
Venous
pressure
(VP)
80
60
VP-AP
40
20
0
Arterial
pressure
(AP)
-20
-40
-60
0
Pro’s & Con’s
0.2
0.4
0.6
0.8
1
1.2
- Cannot ensure detection of needle
disconnected under blanket…
- Sensitive to disturbances from one
side only (VP or AP)
- Cannot determine if a patient is
possible to supervise or not
1.4
© 2013, Gambro
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Principle of new method: VNM Stethoscope
1. Listen to the heart pulse via the blood lines
Heart pulse detected in venous pressure
© 2013, Gambro
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Principle of new method: VNM Stethoscope
1. Listen to the heart pulse via the blood lines
2. Loss of signal indicates dislodgement
No heart pulse
© 2013, Gambro
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Monitoring of Heart Pulses with
Venous and Arterial Pressure Sensors
Venous pressure sensor
Arterial
pressure
sensor
Arterial
needle
Venous
needle
Venous or Arterial Pressure
=
+
Blood
pump
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Dislodgement Indication Technique
Correlation between both blood lines (index between -1 and 1)
Both needles connected:
Disconnection of venous needle:
♦Heart pulses are present in both the
venous and arterial pressure,
♦Heart pulses are only present in
the arterial pressure,
♦“Pressure variations in blood lines are
similar” = high correlation.
♦“Pressure variations in blood lines
are different” = low correlation.
Arterial line
Venous line
Variations are similar
Variations are different
© 2013, Gambro
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Gambro VNM by ”Stethoscope Technology”
Heart pulse is extracted from both venous
and arterial pressure
Extraction performed with blood pump
stopped (easy) and running (advanced
algorithms)
Dislodgement detection only during
stopped blood pump
…
Pro’s & Con’s
+ Determines if a patient is
possible to supervise
+ Very high sensitivity
+ No false alarms
+ Low cost
+ No disposables
+ Platform for other applications:
heart arrythmia, sleep apnea,
hypotension, reversed needles
- Non-supervisible patients
need alternative monitoring
© 2013, Gambro
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Clinical test of dislodgement ability
Successful detection of dislodgement!
Pulse before dislodgement
Pressure
Venous & Arterial
8000
6000
4000
2000
Adaptive
filtering
0
-2000
-4000
0
2
4
6
8
10
s
Pulse after dislodgement
-6000
-8000
1.95
1.952
1.954
1.956
1.958
1.96
1.962
1.964
1.966
Time
time
x 10
6
Blood flow change
500 -> 200 ml/min
DISLODGEMENT
(Venous pressure drop ~30mmHg)
0
2
4
6
8
10
s
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Physiological signals during BP-stop
Example 1.
Heart pulsation visible
Venous pressure
250
strong signal ~15mmHg (top-top)
200
mmHg
150
30
100
25
mmHg
20
50
15
10
5
0
0
50
100
150
200
treatment time (min)
250
300
0
60.7
60.8
60.9
61
61.1 61.2
treatment time (min)
61.3
61.4
61.5
Blood pump is stopped
during 30 s
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Physiological signals during BP-stop, cont’d
Heart pulsation & breathing visible
Example 2.
Weak heart ~0.3mmHg (top-top)
Venous pressure
Venous pressure
250
-20
200
-25
mmHg
100
-30
-35
50
-40
V enous pres s ure
-32.5
-45
0
-33
67.3
-50
67.4
67.5
67.6 67.7 67.8 67.9
-33.5
treatment
time (min)
68
68.1
68.2
mmHg
mmHg
150
0
50
100
150
treatment time (min)
Blood pump is stopped
during 30 s
200
-34
-34.5
-35
67.6
67.65
67.7
treatm ent tim e (m in)
© 2013, Gambro
67.75
26
Physiological signals during BP-stop
conclusions
♦Analysis of physiological signal possible during BP-stop
♦No advanced filtering is needed
♦BP-stop duration is limited due to
♦ Risk for coagulation (1 min is safe)
♦ Reduction of dialysis dose/ delay of treatment
♦BP-stop are suitable
♦ Directly after connection of needles
♦ In conjunction with UF-tarations
♦
Which applications would be suited for BP-stops?
© 2013, Gambro
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1. Detection of needle connection
• Detection of physiological signals in venous and/or arterial blood
line during BP-stop just after needle connection
•Indication that needle connection is completed
•Safety procedures of Protective System may be
started automatically
Serious adverse events may be avoided:
e.g. priming solution pumped into patient
© 2013, Gambro
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2. Detection of reversed needles
Important to avoid reduction of dialysis dose
Correct position of needles
Venous
heart beat
Arterial
heart beat
Reversed needles
Venous
heart beat
Arterial
heart beat
Detection by changes of amplitude, phase and shape
Automatic detection of reversed needle fault may be performed
during BP-stop after connection of needles
© 2013, Gambro
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Heart signal analysis by ”Stethoscope Technology”
potential applications
♦Heart rhythm/status monitoring
♦Heart rate (HR)
♦Arrhythmia detection
♦Ectopic beats
♦Atrial fibrillation
♦Heart rate variability (HRV), autonomic balance
Timing information
Ectopic beat
© 2013, Gambro
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Breathing, potential application 1
♦VNM by analysis of breathing signal
♦ “Breathing signal disappears as needles slips out”
♦ Advantage: complementary to VNM by heart signal
Venous
pressure
Arterial
pressure
Breathing signal
(external sensor)
© 2013, Gambro
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Breathing, potential application 2
♦Detection of Sleep Apnea
♦Increased morbidity (hypertension, coronary artery disease,
arrhythmias, heart failure, and stroke)
♦Elevated prevalence in dialysis patients 30%-50% (healthy <10%)
♦Not always linked with snoring
♦Surveillance & screening of unattended patients: nocturnal & home…
© 2013, Gambro
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How to predict blood pressure drops during
dialysis…
2.
1. ”Refilling”
Relative blood volume
BVS
1.
2. Heart activity
Heart rate, stroke volume
ECG: HRV, EBC, HRT…
3.
.
3. Vasconstriction
Capillaries & extermities
central blood volume, BIA
capillary pulse, pulsoximeter
Ultrafiltration ≈ 0.5 l/h
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Pulsoximeter
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How does it work?
Optical
measurement
1.
Light absorption depends on oxygen
saturation and blood volume in the vessel
2.
Blood volume in vessel depends on
vasoconstriction
3.
Vasoconstriction can be estimated from the
light absorption reading
• Oxygen saturation
• Capillary pulse signal
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Vasoconstriction & capillary pulse
Relative magnitude of capillary pulse signal
⇔
vasoconstriction change
Envelope
Amplitude
Integral
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Result from clinical study in Copenhagen
28 treatments totally
In 3 treatments the pulseoximeter could not be used due to cold
hands or sensor problems
17 treatments without blood pressure drops
7 acute hypotensive episodes in 5 treatments (2 treatments with
double pressure drops)
2 slow blood pressure drops over the entire treatments
1 treatment where the patient had consistently low blood pressure
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Patient with stable blood pressure
Relative
Relative magnitude
magnitude of
of capillary
capillary pulse
pulse
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Patient with acute blood pressure drop
Blood pressure drop
Relative magnitude of capillary pulse
Threshold=0.75
Threshold=0.55
15
min
5 min
© 2013, Gambro
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Results
PD=probablity of detection, PFA =probability of false alarms
0.54
PD=100%, PFA=0%,
=0% pred time=38min
PD
Prediction
time
Threshold
Threshold
Average
prediction
time
PFA
Threshold
Threshold
© 2013, Gambro
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Capillary pulse hypothesis
Prior to a blood pressure drop a protective response of body to
prevent hypotension is started
First priority is blood pressure in the central, vital organs (brain,
heart)
Vasoconstriction

The capillary pulse signal is attenuated/depleted
© 2013, Gambro
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Hypotension prediction
Application: Early warning of hypotension to allow prevention of adverse events
Hypothesis:
Pulse
pressure
and PPG
Start of
treatment
End of
treatment
Reduction of heart signal
may predict acute
symptomatic hypotension
(as for PPG-signal)
Indication:
Amplitude of heart pressure
pulse (VP & AP) decrease
over treatment similar to
PPG signal
time
Art heart= red, Ven heart = blue, PPG = green
Confidential for Vinnova
© 2013, Gambro
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So ....
Many interesting possibilities for
patient monitoring remain to be
explored
© 2013, Gambro
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