526 
HEMODYNAMICS 
— , 10 
Q 
O 
O 
< 
z 
o 
o 
u. 
o 
>- 
O 
u 
to 
10 
10' 
10 
h(%) 
34 ELEPHANT 
44 man: 
44 DOG -V 
37 TURKEY 
37 SHEEP._ 
29 GOAT — 
TEMP. = 37 C 
44 MAN. 
TEMP. X 20 'C 
29 AMPHIUMA 
24 FROG--'-.,u.;- 
31 TURTLE 
10" 
,-2 
1 I I mill I I 1 1 II 
' I 1 I ri III I 1 I I mil 
10"' 1 10 
SHEAR RATE (sec"') 
10^ 
Figure 1. — Eelation between viscosity of original 
whole blood and shear rate, (from ref. 1). 
cells are dispersed. As shear rate increases, fluid 
forces cause rouleaux to flex (so they have a 
smaller effective size) and disperse. At low 
shear rates individual cells appear rigid. As 
shear rate increases further, rouleaux are fur- 
ther dismantled and individual cells begin to 
flex — sweeping a smaller effective volume as 
they rotate. 
10 
8io 
^10 
1 1 
3 
1 1 
1 r- 
455.HumQn Medium 
RBC (lo^'^'^P) - 
^ — ^^^"""^--^ 
N P : 
NA: 
HA: 
Normal Plasma 
Normal 11*/. Alb. 
Hardened 11 X Alb. 
- Aggregation 
^ HA 
C-...0 
r NA 
Deformation 
— 1 I'll ""I ' 
1 1 1 1 1 1 ll 1 1 1 I 1 1 111 
10-= 10-' 
1 10 10' 10' 
SHEAR RATE (sec-'l 
Figure 2. — Relation between relative viscosity and 
shear rate of human normal RBC in plasma, normal 
RBC in 11% Albumin-Ringer, and hardened RBC in 
11% Albumin-Ringer, (from ref. 1). 
Figure 3. — Election micrograph of RBC suspended in 
Dextran with a mean molecular weight of over one 
million, (from ref. 1). 
Interestingly, the ability to form rouleaux 
depends upon cell deformability. Figure 3 shows 
how cells must deform in order to form rou- 
leaux. The ability to deform is thought to be 
related to the surface to volume ratio, mem- 
brane flexibility and perhaps to internal 
viscosity. 
An idea of size and shapes of the cells tested 
can be obtained from Figure 4 (note goat cells 
do not spontaneously form rouleaux). Average 
statistics of cells examined are given in Table I. 
Note the mean corpuscular hemoglobin concen- 
tration (MCHC) varies but little suggesting 
that in isotonic suspensions the internal viscos- 
ity will not vary from species to species. Also 
note the sphericity index appears to be a mono- 
tonic function of cell volume. More will be said 
of this in the next section. 
Cell deformability is classified by filter tests 
in Figure 5. Note the results for the mammalian 
cells are grouped closely together despite large 
cell diameter variations. This is because the 
small cells are less deformable due to, for the 
most part, their high sphericity index. Similarly 
high sphericity index impairs the tendency to 
form rouleaux. This can be seen in Figure 6. The 
