Voytek Bosek, M.D.
Associate Professor of Anesthesiology,
University of South Florida
H. Lee Moffitt Cancer Center and Research Institute
Tampa, Florida
bosekv@moffitt.usf.edu
Postoperative outcome in the elderly is determined by their
compensatory capacity to offset the effect of perioperative
stress, such as blood loss. During blood loss, several defensive
mechanisms are activated. One of these mechanisms is the translocation
of water from extravascular space into the intravascular compartment
that results in hemodilution. Similarly, preoperative acute
normovolemic hemodilution (ANH) has been introduced into clinical
practice whereby blood is removed and simultaneously replaced
with an appropriate volume of crystalloid and/or colloid. The
application of ANH may decrease the need for allogenic blood
transfusion, thereby decreasing the risk of transfusion-transmitted
disease, transfusion reactions and cost. Subsequent reinfusion
of the patientās own blood may also help preserve platelet function.
There is some hesitancy to use acute normovolemic hemodilution
in the elderly due to these patients' limited capacity to increase
cardiac output, in part due to their reduced ²-receptor
responsiveness.1 Nevertheless,
there is a strong desire to avoid allogenic blood transfusion
under at least some surgical circumstances, such as colorectal
and hepatic cancer surgery where perioperative use of allogenic
blood transfusion has been shown to increase tumor recurrence.4,5
Acute normovolemic hemodilution may help minimize such transfusion.
Recent studies have shown that the danger of ANH in the elderly
had been exaggerated.
For example, when 2 units of blood were removed and replaced
with an equal volume of 6 percent hydroxyethyl starch in a group
of elderly ASA I-III patients scheduled for noncardiac surgery,
cardiac output increased mainly due to an increase in stroke
volume; the heart rate did not change.2
Oxygen extraction increased, oxygen consumption remained stable
and mean arterial pressure and systemic vascular resistance
both decreased slightly. No patient developed ST segment alterations
suggestive of myocardial ischemia. During the surgical procedure,
after preoperative hemodilution, hemoglobin decreased further,
and the autologous blood was transfused to achieve a hemoglobin
value of 7.7 g/dL. Even at the lowest hemoglobin level encountered,
there were no direct nor indirect signs of myocardial ischemia
such as ST segment deviation, hypotension, arrhythmias or increased
filling pressure. In a group of elderly patients scheduled for
cardiac surgery, ANH produced increases in cardiac output, oxygen
transport capacity and decreases in systemic vascular resistance
and myocardial oxygen consumption.3
No signs of ischemia were found in either the EKG or the EEG
during hemodilution.
For these reasons, it is safe to conclude that moderate ANH
can be performed in at least reasonably healthy elderly patients
undergoing cardiac or noncardiac operations.
References:
1. Roseberg B, Wulff K. Hemodynamics
following normovolemic hemodilution in elderly patients. Acta
Anaesthesiol Scand. 1981; 25(5):402-406.
2. Spahn DR, Zollinger A, Schlumpf RB,
et al. Hemodilution tolerance in elderly patients without
known cardiac disease. Anesth Analg. 1996; 82:681-686.
3. Murday HK, Jungblut M. How safe is
isovolemic hemodilution in elderly patients at risk? Clinical
studies of geriatric heart surgery. Anasth Intensivther Notf
Med. 1990; 25(5):335-339.
4. Yamamoto J, Kosuge T, Takamaya T, et
al. Perioperative blood transfusion promotes recurrence of
hepatocellular carcinoma after hepatectomy. Surgery.
1994; 115:303-309.
5. Rosen CB, Nagorney DM, Taswell HF,
et al. Perioperative blood transfusion and determinants of
survival after liver resection for metastatic colorectal carcinoma.
Ann Surg. 1992; 216:493-505.