6/10/1999Mansfield, MA Approximate calculation of needed pump speed (PS) t = Kt/V * V/K * 1000 K =...

6/10/1999 Mansfield, MA

Approximate calculation of needed pump speed (PS)

t = Kt/V * V/K * 1000

K = Kt/V *V/t*1000

t = 1.3 *40/300*1000 = 173 min

K = 1.3 *40/240 *1000 = 217K = 1.3 *50/240 *1000 = 270

Pump speed vs. clearance with F-80 dialyzerPS = 400; Blood Flow = 360; K = 270

6/10/1999 Mansfield, MA

Approximate calculation of needed pump speed (PS)

t = (Kt/V) * (V/K) * 1000

K = (Kt/V) *(V/t)*1000

t = 1.6 *(40/270)*1000 = 237 min

K = 1.6 *(40/240) *1000 = 267K = 1.6 *(50/240) *1000 = 333

Pump speed vs. clearance with F-80 dialyzerPS = 400; Blood Flow = 360; K = 270

6/10/1999 Mansfield, MA

Blood flow through the catheter Design

– Length– Diameter– Cross section

Tip location Tip occlusion

– Fibrin sheath– Ball thrombus– Mural thrombus

6/10/1999 Mansfield, MA

Catheter design

Q p r

4

8L

Poiseuille’s equation

Flow in catheters is directly proportional to the pressure difference and the 4th power of thelumen radius, and inversely proportional to the lumen length and the viscosity of fluid (blood)

In lumens deviating from circular, resistance is higher(flow is lower at the same length and cross section)

6/10/1999 Mansfield, MA

Negative Pressure (mm Hg)

-400 -300 -200 -100 0

Blo

od

Flo

w (

ml/m

in)

0

100

200

300

400

500

600

SNIJ Flush TipSNIJ StaggeredPermCathAccess Cath MedcompSoft Cell Vas Cath

SNIJ - linear regression

Others - linear regression

SNIJ: y = -1.78x + 0.33 r

2 = 0.92

Others: y = -1.15x + 42.2

r2 = 0.95

6/10/1999 Mansfield, MA

6/10/1999 Mansfield, MA

Tip location

The best tip location is at the superior vena cava/right atrium junction

Flows are usually worse with other locations

6/10/1999 Mansfield, MA

Tip in right brachiocephalic

vein

6/10/1999 Mansfield, MA

Tip in rightbrachiocephalic

vein

6/10/1999 Mansfield, MA

Catheter tip in the mid-SVC

6/10/1999 Mansfield, MA

Tip in right atrium

6/10/1999 Mansfield, MA

Inflow in left brachicephalic vein

Outflow in SVCagainst the wall

6/10/1999 Mansfield, MA

Inflow against wall

Outflow tip

6/10/1999 Mansfield, MA

Tip low in atrium

6/10/1999 Mansfield, MA

Tip in the mid right atrium

6/10/1999 Mansfield, MA

Tip close toinferior vena

cava

Opti-Flow

6/10/1999 Mansfield, MA

Tip in right

ventricle

6/10/1999 Mansfield, MA

Tip in right

ventricle

6/10/1999 Mansfield, MA

Tip occlusion

Fibrin sheath (sleeve) - probably on all catheters– Asymptomatic– Poor or no inflow when involving catheter tip

Ball thrombus– A large clot adherent to the catheter tip but not to the

vessel wall. Difficult to dissolve, can be stripped

Mural thrombus– A large clot adherent to both catheter and vessel wall and

causing partial or complete occlusion of the vessel

6/10/1999 Mansfield, MA

FibrinSheath

Formation

6/10/1999 Mansfield, MA

FibrinSheath

Formation

Inflow tip occluded

6/10/1999 Mansfield, MA

FibrinSheath

Formation

Inflow tip occluded

6/10/1999 Mansfield, MA

FibrinSheath

Formation

Both tips occluded

6/10/1999 Mansfield, MA

Tip occlusion

Fibrin sheath (sleeve) - probably on all catheters– Asymptomatic– Poor or no inflow when involving catheter tip

Ball thrombus– A large clot adherent to the catheter tip but not to the

vessel wall. Difficult to dissolve, can be stripped

Mural thrombus– A large clot adherent to both catheter and vessel wall and

causing partial or complete occlusion of the vessel

6/10/1999 Mansfield, MA

Ball thrombus removed with catheter

6/10/1999 Mansfield, MA

Ball thrombus, closer view