Vol. 283, Issue 3, H1191-H1199, September 2002
Systemic and microvascular responses to hemorrhagic shock and
resuscitation with Hb vesicles
Hiromi
Sakai1,
Shinji
Takeoka1,
Reto
Wettstein2,
Amy G.
Tsai2,
Marcos
Intaglietta2, and
Eishun
Tsuchida1
1 Advanced Research Institute for Science and
Engineering, Waseda University, Tokyo 169-8555, Japan;
and 2 Department of Bioengineering, University of
California, San Diego, La Jolla, California 92093-0412
A phospholipid vesicle encapsulating
hemoglobin (Hb vesicle, HbV) has been developed to provide
O2-carrying capacity to plasma expanders. Its ability to
restore systemic and microcirculatory conditions after hemorrhagic
shock was evaluated in the dorsal skinfold window preparation of
conscious hamsters. The HbV was suspended in 8% human serum albumin
(HSA) at Hb concentrations of 3.8 g/dl [HbV(3.8)/HSA] and 7.6 g/dl
[HbV(7.6)/HSA]. Shock was induced by 50% blood withdrawal, and mean
arterial pressure (MAP) at 40 mmHg was maintained for 1 h by the
additional blood withdrawal. The hamsters receiving either HbV(3.8)/HSA
or HbV(7.6)/HSA suspensions restored MAP to 93 ± 14 and 93 ± 10 mmHg, respectively, similar with those receiving the shed blood
(98 ± 13 mmHg), which were significantly higher by comparison
with resuscitation with HSA alone (62 ± 12 mmHg). Only the HSA
group tended to maintain hyperventilation and negative base excess
after the resuscitation. Subcutaneous microvascular blood flow reduced
to ~10-20% of baseline during shock, and reinfusion of shed
blood restored blood flow to ~60-80% of baseline, an effect
primarily due to the sustained constriction of small arteries
A0 (diameter 143 ± 29 µm). The HbV(3.8)/HSA group
had significantly better microvascular blood flow recovery and
nonsignificantly better tissue oxygenation than of the HSA group. The
recovery of base excess and improved tissue oxygenation appears to be
primarily due to the increased oxygen-carrying capacity of HbV fluid resuscitation.
blood substitutes; artificial red blood cells; microcirculation; microhemodynamics; liposome