转自UpTo Date 网的综述:Acute normovolemic (isovolemic) hemodilution (ANH)
Author
Arthur J Silvergleid, MD
INTRODUCTION — Acute normovolemic (isovolemic)
hemodilution (ANH), also referred to as intraoperative hemodilution, was
introduced in the early l970s . This blood conservation technique
entails the removal of blood from a patient, either immediately before
or shortly after induction of anesthesia, with maintenance of isovolemia
using crystalloid and/or colloid replacement. The amount of blood
removed varies between one and three units (450 to 500 mL constitutes
one unit), although larger volumes may be withdrawn safely in certain
circumstances (see below).
The blood withdrawn is anticoagulated and maintained at room
temperature, in the operating room, for up to eight hours. It is
reinfused into the patient as needed during, or after, the surgical
procedure. ANH can be used as the sole blood conservation technique, or
it can be combined with preoperative autologous donation blood
salvage or both.
INDICATIONS AND CONTRAINDICATIONS
— ANH should be considered for patients with good initial hematocrits
who are expected to lose more than two units of blood (900 to 1000 mL)
during surgery. This technique is better suited to healthy, young
adults, but it has been successfully employed in small children and the
elderly. Operative settings in which ANH is appropriate include
vascular, orthopedic, and some general surgical procedures. In addition,
some Jehovah's Witnesses will agree to ANH if the blood is maintained
in a closed circuit continuous flow system 。
ANH is contraindicated in the following settings:
Cardiac disease, since the main compensatory mechanism for the
induced anemia is an increase in the cardiac output. However, the
decreased blood viscosity associated with the induced anemia may have
cardioprotective effects in some cardiac surgical settings 。Impaired renal function, since large amounts of infused fluids need to be excreted.Baseline hemoglobin