New professionals in the ICU

Intensivistendagen 2014 J.G. van der Hoeven

„New” professionals

• Nurse practitioner

• Nurse specialist

• Physician assistant

• Technical medicine

Technical medicine

• 2003 - start bachelor Clinical Technology

• 2006 - start master Technical Medicine

• 2013 - registration of Technical Medicine in the Dutch register for Professions in Health Care

Technical Physician• Performs and optimizes complex technical-medical

procedures

• Designs and develops innovations and improvements in diagnosis and/or therapy with the use of technology

Competence domains• Technical medicine

• Research and design

• Technical-medical practice

• Scientific approach

• Reasoning, reflecting and judgment

• Professional behavior

• Situational „awareness” (temporal, social, organizational)

Bachelor clinical technology

Q1! Q2! Q3! Q4

1 Anatomy/Imaging Cell biology

Introduction pathophysiological core

concepts

Proces signaling (Matlab) Regulation/integration

Blood- and immune system Rotation

Functions of 1 variable TG project Signal analysis Communication skills 3 D mathematics

Professional behavior

2 Cardiovascular system Academic skills

Respiratory system Digestive system Neural system Body in motion + project

Vector analysis

Communication skills and professional behavior

Communication skills and professional behavior

Epidemiology and medical statistics Health care law

3 Sensory system Academic skills Urogenital system

Applied cell biology Biomaterials and human

body interactionMultidisciplinary assignment

Epidemiology and medical statistics / MTA Medical technology ethics Health care law

Master curriculum (M1)Medical

SignalingRobotics and

ImagingReconstructive

medicine

First quartileBiological control systems Circulation & Ventilation!Injection, punctures and

catheterizations!Case 1

Radiation expertise Imaging technologies

Injection, punctures and catheterizations!

Case 1

Elective course Cellular pathology

Injection, punctures and catheterizations!

Case 1

Second quartileAdvanced signal analysis

Elective course Surgical skills

Microscopic detection Elective course Surgical skills

Microscopic detection Advanced cell biology

Surgical skills

Third quartileHuman motor control

Biomedical signal acquisition Advanced life support!

Case 2

Reconstruction and visualization

Robotics Advanced life support!

Case 2

Elective course Immunology & Transplantation!

Advanced life support!Case 2

Fourth quartileNeural networks Elective course

Endoscopic skills

Elective cours Surgical navigation technology

Endoscopic skills

Tissue engineering Biomaterials & human body

Endoscopic skills

Master curriculum (M2&3)M2 M3

First quartile Clinical rotations

Laboratory animal science (3 EC)

!+ !

Clinical specialization rotation (57 EC)

Second quartile Clinical rotations

Third quartile Clinical rotations

Fourth quartile Clinical rotations

EC = European credit point = 28 study hours

Clinical fellowship• Two years

• Clinical practice clearly separated from research

• Training in a specific subject with the aim of employment in this field

Radboudumc - expert in mechanical ventilation

Just a few examples (M1)The Patient Tilt Technique as a new method for measurement of MSFP in critically ill patients.

Figure 5: Optical coherence tomographic scan of a pig’scoronary artery. (Reprinted from [42].)

coronary arteries [41]. OCT uses light which isemitted on the target tissue. A part of the lightis scattered, but another part is re�ected by thetissue. The collected part of the back-re�ectedlight is compared with the original beam. Thephase di�erence depends on how long the beamwas on the go. With these data an image can beconstructed [40] as in �gure 5.

3.3. TILTING THE PATIENT

Lifting the legs of a lying patient induces grav-itational transfer of blood from the legs to thecentral circulatory compartment [43]. This can beexplained by equation (5). Raising the legs causesthe blood pressure to increase because of an in-creasing hydrostatic pressure. Due to the higherpressure the blood will �ow from the legs to theheart. The research of Rutlen et al. [44] showedthat leg elevation of 20�, which corresponds withan ankle raised 20 cm above the examining table,will lead to transfer approximately 150 ml blood.

Di�erent blood �ows can be created by liftingthe legs in di�erent angles. A disadvantageof this method is that there is hip �exion andpossible femoral catheter movement which cancause pain-induced sympathetic stimulation [43].Therefore it is better to lie the patient horizon-tally and tilt the entire bed. A pro of this methodis that it induces a larger blood volume to �ow,because the blood in the large splanchnic com-partment is also mobilised [43]. Di�erent blood

θ

Figure 6: A schematic illustration of tilting the entire bedin di�erent angles. An angle moving the patient’shead up is de�ned as positive. An angle of 20� isdisplayed.

�ows can be created by changing how much youtilt the bed as in �gure 6.

3.3.1. Time when the e�ect can be measured

When passive leg raising is used as explainedabove, blood will �ow from the legs to the heart.This causes the VR to increase and therefore thevenous pressure increases as well. This e�ect willvanish over time. One explanation for the disap-pearance of the e�ect is that the body adapts ina way a steady state can be reached. Anotherreason may be the capillary leak, caused by ex-tended blood volume. In healthy patients thee�ect of the extended volume vanishes in about10 minutes, in patients it does not always sustainover 10 minutes [43, 45]. For example, patients inseptic shock have more capillary leak [43], caus-ing the e�ect to be present for a shorter time.When tilting the bed, the e�ect will also vanishin the end. It is important to do the measure-ments when the e�ect is present since di�erentblood �ows corresponding with di�erent venouspressures need to be measured. Therefore themeasurements should take place as soon as pos-sible as the e�ect is present.

Research has shown that the e�ect of passive legraising rapidly occurs after starting the maneu-ver and the biggest e�ect is observed within the�rst thirty seconds [46]. Therefore the pressureand �ow should be measured in the �rst thirtyseconds after tilting the bed. When the pressureand �ow will be measured after this time, therestill will be a di�erent pressure and �ow, but thee�ect is less present.

11

The Patient Tilt Technique as a new method for measurement of MSFP in critically ill patients.

Figure 5: Optical coherence tomographic scan of a pig’scoronary artery. (Reprinted from [42].)

coronary arteries [41]. OCT uses light which isemitted on the target tissue. A part of the lightis scattered, but another part is re�ected by thetissue. The collected part of the back-re�ectedlight is compared with the original beam. Thephase di�erence depends on how long the beamwas on the go. With these data an image can beconstructed [40] as in �gure 5.

3.3. TILTING THE PATIENT

Lifting the legs of a lying patient induces grav-itational transfer of blood from the legs to thecentral circulatory compartment [43]. This can beexplained by equation (5). Raising the legs causesthe blood pressure to increase because of an in-creasing hydrostatic pressure. Due to the higherpressure the blood will �ow from the legs to theheart. The research of Rutlen et al. [44] showedthat leg elevation of 20�, which corresponds withan ankle raised 20 cm above the examining table,will lead to transfer approximately 150 ml blood.

Di�erent blood �ows can be created by liftingthe legs in di�erent angles. A disadvantageof this method is that there is hip �exion andpossible femoral catheter movement which cancause pain-induced sympathetic stimulation [43].Therefore it is better to lie the patient horizon-tally and tilt the entire bed. A pro of this methodis that it induces a larger blood volume to �ow,because the blood in the large splanchnic com-partment is also mobilised [43]. Di�erent blood

θ

Figure 6: A schematic illustration of tilting the entire bedin di�erent angles. An angle moving the patient’shead up is de�ned as positive. An angle of 20� isdisplayed.

�ows can be created by changing how much youtilt the bed as in �gure 6.

3.3.1. Time when the e�ect can be measured

When passive leg raising is used as explainedabove, blood will �ow from the legs to the heart.This causes the VR to increase and therefore thevenous pressure increases as well. This e�ect willvanish over time. One explanation for the disap-pearance of the e�ect is that the body adapts ina way a steady state can be reached. Anotherreason may be the capillary leak, caused by ex-tended blood volume. In healthy patients thee�ect of the extended volume vanishes in about10 minutes, in patients it does not always sustainover 10 minutes [43, 45]. For example, patients inseptic shock have more capillary leak [43], caus-ing the e�ect to be present for a shorter time.When tilting the bed, the e�ect will also vanishin the end. It is important to do the measure-ments when the e�ect is present since di�erentblood �ows corresponding with di�erent venouspressures need to be measured. Therefore themeasurements should take place as soon as pos-sible as the e�ect is present.

Research has shown that the e�ect of passive legraising rapidly occurs after starting the maneu-ver and the biggest e�ect is observed within the�rst thirty seconds [46]. Therefore the pressureand �ow should be measured in the �rst thirtyseconds after tilting the bed. When the pressureand �ow will be measured after this time, therestill will be a di�erent pressure and �ow, but thee�ect is less present.

11

The Patient Tilt Technique as a new method for measurement of MSFP in critically ill patients.

20 25 30

0

0.5

1

P (mmHg)

Q̇(m

L/m

in)

pressure P vs. �ow Q̇ data pointsPTT demo �tzero of �t

Figure 9: Demonstration of a �t for randomly chosen pres-sure P vs. �ow Q̇. The extrapolation of theMSFP is the black circle (‘zero’) on the �ttedcurve.

�ows). This means a twice as large increase inpressure results in a twice as large increase in ra-dius of the vessel. Assuming dP/dt is very smallshortly after tilting the patient, i.e. C · dP/dt ⌧�P/R, equation (8) becomes equation (6) again.In this equation, the resistance is a function ofpressure: R(P), described by equation (7). So:R / 1/�P4 and Q̇ / �P4. This means the extrap-olation must be done by �tting a fourth-orderpolynomial on the acquired data points. Fit func-tion f (P) has the form

f (P) ⇤ aP4 + b , (9)

and is depicted in �gure 9 for arbitrary datapoints. Appendix B describes how the graphwas created.

3.5. PHYSIOLOGICAL REACTION ON TILTINGTHE BED

3.5.1. The tilt angle influences the pressure

During the measurement, the patient’s bed istilted at various angles. The consequence is a dif-ferent hydrostatic pressure in the vein dependingon the angle. When the bed is rotated, the loca-tion of the measurement device changes in heightwith respect to the axis of rotation. This pres-sure di�erence between two heights is denotedby equation (5). The height di�erence h1 � h2

depends sinusoidally on the angle ✓,

h1 � h2 ⇤ l sin ✓, (10)

where l is the distance from the axis of rotationand the point of measurement along the patient.Angle ✓ is de�ned such that increasing the angleraises the patient’s head.

Combining equations (5) and (10) provides

�P ⇤ �⇢gl sin ✓. (11)

In other words: increasing the angle such that thevena jugularis interna increases in height, willdecrease the pressure in the vein (and vice versa).

3.5.2. The tilt angle influences the flow

Tilting changes the �ow in the vena jugularisinterna as well as the pressure. This dependson various conditions. These conditions are allbased on the same principle: change in pressureresults in �ow if resistance is not in�nite. Somebasic examples illustrate this statement.

One example is the heart. When it pumps outblood, the diastolic pressure is increased up tosystolic pressure. The result is a �ow from highto low pressure. This is the driving pressure.

Another pressure that can induce a �ow is hydro-static pressure, described already in the previoussection. When a height di�erence is introduced,gravity will pull from the mass of the volumeand it will �ow towards a lower area.

These �ows can only exist when the resistanceto �ow is not in�nite. An example of an in�niteresistance is a Valsalva manoeuvre [53]. This isdone by trying to breathe out, without openingthe throat so that no air can �ow out. Intratho-racic pressure increases without a �ow. However,if the throat is opened, the resistance becomeslower and �ow can commence.

3.6. MEASUREMENT SITE

The MSFP re�ects a parameter of the vascularbeds and is localised in the venous system. Thelocation within the circulation can be describedby the resistance of venous return divided bythe systemic vascular resistance [15]. The higherthis ratio, the more upstream the position of the

14

The Patient Tilt Technique as a new method for measurement of MSFP in critically ill patients.

Figure 13: Protocol for tilting the bed.

APPENDICES

A. PROTOCOL FOR THE PATIENT TILTTECHNIQUE

Figure 13 shows in which angles the bed shouldbe tilted. Below is the step by step protocol forthe Patient Tilt Technique.

1. Check the patient for contra-indications. Pre-pare the patient and the machines for �owand pressure measurements. Place the RIPbands on the patients. Put the patient in a�at position.

2. The bed tilts itself in an angle of approxi-mately 10�. When the RIP bands gives asignal, measure the �ow and pressure in thevena jugularis interna.

3. The bed tilts itself to an angle of 0�. After 1minute the bed tilts itself in an angle of ap-proximately 20�. When the RIP bands givesa signal, measure the �ow and pressure inthe vena jugularis interna.

4. The bed tilts itself to an angle of 0�. After 1minute the bed tilts itself in an angle of ap-proximately -10�. When the RIP bands givesa signal, measure the �ow and pressure inthe vena jugularis interna.

5. The bed tilts itself to an angle of 0�. After 1minute the bed tilts itself in an angle of ap-proximately -20�. When the RIP bands givesa signal, measure the �ow and pressure inthe vena jugularis interna.

6. Put the patient back to its original position.

7. Put the measured values in a Matlab script,which extrapolates the blood �ow to zero.The script gives the corresponding bloodpressure which is equal to the MSFP.

B. IMPLEMENTATION OF THE PTT FITDEMO IN MATLAB

Figure 9 was implemented in MATLAB® R2013ausing the following code�.

1function PTTfitdemo

2% PTTFITDEMO

3%

4% Demo for the Patient Tilt Technique

data extrapolation: just run the

5% function.

6

7% P- and Q-data points. They are

chosen randomly, but they are

8% physiological for driving pressure

P and flow Q in a blood vessel. The

9P = [20 21 23 26 30]; % driving

pressure (mmHg)

10Q = [.04 .07 .1 .3 .7]; % resulting

flow (mL/min)

11

12% the fit

13fit = createFit(P, Q);

14

15% the fit is evaluated

16Pfit = 16:32;

17Qfit = feval(fit,Pfit);

18

19% find the root of the fit

20p = coeffvalues(fit);

21root = max(real(roots(p)));

22

23% Plot fit with data.

24figure( ’Name’, ’PTT demo fit’ );

25h = plot( P, Q, ’b*’, Pfit, Qfit, ’r-

’, root, 0, ’ko’ );

26legend( h, ’pressure P vs. flow Q’’

data points’, ’PTT demo fit’, ’zero

of fit’, ’Location’, ’Northwest’ )

;

27title(’pressure P vs. flow Q’’ with

fit and zero’)

28xlabel( ’P (mmHg)’ );

29ylabel( ’Q’’ (mL/min)’ );

30grid on

31

32end

33

34function fitresult = createFit(P, Q)

35% Data for fit:

36% X Input : x

�The .m-�le of the code is provided as an attachment inthe digital version of this document (in this same footnote).

24

Measuring mean systemic filling pressure

Just a few examples (M2)Measuring auto regulation after cardiac arrest

Just a few examples (M3)Upper airway opening in relation to diaphragm activity

Levosimendan improves neuromechanical efficiencyDoorduin J. Am J Respir Crit Care Med 2012;185:90-95

Analysis of difficult weaning

TLC$

0$Ppl$/$Pes$ +$-$

FRC$

Lung$volume$

passive$infla9on$$(relaxed$chestwall)$

ac9ve$infla9on$(lung$elas9c$recoil)$

resis9ve$inspiratory$WOB$

elas9c$inspiratory$WOB$

PEEPi

PEEPi$inspiratory$WOB$

expiratory$WOB$FRC$

Vt$

Vt$

0 2 4 6 8 10 12 14 16 1820

40

60

80

100

120

140

160

180

ABP

(mm

Hg)

SVI (

ml/m

2)

Time (s)

0 2 4 6 8 10 12 14 16 180

5

10

15

20

25

30

Time (s)

Pres

sure

(mm

Hg)

ABP

Ppl

Paw

Ppc

CVP

SVI

0 20 400

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8PV−loop Paw

Pressure (cmH2O)

Volu

me

(L)

0 10 200

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8PV−loop Ppl

Pressure (mmHg)

Volu

me

(L)

5 10 150

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8PV−loop Ppc

Pressure (mmHg)

Volu

me

(L)

Transmission index

• Ppleura - 70 ± 27% of alveolar pressure • Ppericard - 37 ± 17% of alveolar pressure • Psvc - 43 ± 11% of alveolar pressure

Transmission increases slightly with lower CW compliance

Volume responderVolume non-responder

Conclusions• Technical physician is complementary to the

„traditional doctor”

• They certainly improve patient care in specific areas

• The stimulate research in previously unknown areas and have innovation as a core competence

• They may play an important role in level III ICU’s