Cardiovascular effects of moderate normovolaemic haemodilution during enflurane–nitrous oxide anaesthesia in man

Abstract

The cardiovascular effects of mild normovolaemic haemodilution during enflurane-nitrous oxide anaesthesia were studied in 20 patients with normal cardiac function before, during and after total hip replacement. After induction of anaesthesia, patients were randomly allocated to one control group (C), or one haemodiluted group (H) where Hct was decreased to 30% by replacement of blood volume by an identical volume of hydroxyethyl starch 200/05. Each patient was monitored with a pulmonary artery catheter allowing the measurement of right ventricular ejection fraction. During haemodilution, stroke index and right ventricular end-diastolic volume index increased from 33.1 +/- 7.9 to 39.3 +/- 7.1 ml.M-2 and from 73.8 +/- 20.3 to 94.9 +/- 18.5 ml.M-2 respectively (mean +/- s.d., both P < 0.05). However, heart rate decreased so that cardiac index did not change. O2 delivery decreased significantly (from 389 +/- 70 to 311 +/- 63 ml.min-1.m-2; P < 0.05), but was not different to the control group. O2 consumption was maintained by an increase in O2 extraction. During the surgical procedure, cardiac index was higher in the haemodiluted group than in the control group, so that O2 delivery was similar in the two groups. O2 consumption tended to be greater in the haemodiluted group. In patients with normal cardiac function, enflurane-nitrous oxide anesthesia could alter the normal physiologic response to mild normovolaemic haemodilution.

A Randomized Trial of Acute Normovolemic Hemodilution Compared to Preoperative Autologous Blood Donation in Total Knee Arthroplasty

“…Recent publications have attempted to define the role of ANH in patients undergoing orthopedic surgery [20, 21, 22, 23, 24]. One report was randomized trial in which 20 patients undergoing total hip arthroplasty underwent ANH (900 ml, or 2 units) and 20 patients underwent ‘natural’ hemodilution during perisurgical blood loss; both groups received transfusion when the intraoperative hematocrit level was <0.25 and the postoperative hematocrit levels was <0.30 [23].…”

“…Mean estimated blood loss was 1,750 ml in both cohorst (ranges 740–4,750 ml), and mean postoperative hematocrit levels were 0.32 and 0.33, respectively (NS). A second report evaluated hemodynamic safety parameters and efficacy in 10 patients who underwent ANH before total hip arthroplasty compared to 10 control patients with no ANH [22]. Despite the small cohort size, the mean allogeneic blood volume transfused was smaller in the ANH compared to the control group (165±270 vs. 1,085±387 ml, respectively).…”

Do We Have Enough Evidence to Know when to Transfuse Erythrocytes?

“…Lesser degrees of acute isovolemic anemia in humans also have not resulted in decreased oxygen consumption [10,11]. Anesthetized patients, in response to acute anemia, do not increase their heart rate [10,11], as do awake humans, perhaps owing to the effects of administered opioids [12]. Nevertheless, these humans, also do not show altered oxygen consumption in response to acute reduction of hemoglobin concentration to 8 g/dl [10,11].…”

“…Even further reduction of DO2 at a hemoglobin concentration of 5 g/dl, to 7.3 ml O2/kg/min does not produce systemic evidence of inadequate oxygenation [9]. Lesser degrees of acute isovolemic anemia in humans also have not resulted in decreased oxygen consumption [10,11]. Anesthetized patients, in response to acute anemia, do not increase their heart rate [10,11], as do awake humans, perhaps owing to the effects of administered opioids [12].…”

Acute Normovolemic Hemodilution

“…Another recent study evaluated the safety of acute hemodilution in patients with coronary artery disease treated with beta-adrenergic blocker therapy 18 . ecent publications have attempted to define the role of acute hemodilution in patients undergoing orthopaedic surgery [19][20][21][22][23][24][25][26] . One report was a randomized trial in which 20 patients undergoing total hip arthroplasty underwent acute hemodilution (900 mL, or two units) and 20 patients underwent natural hemodilution associated with perisurgical blood loss; both groups received transfusions when the intraoperative hematocrit level was less than 25% and the postoperative hematocrit level was less than 30% 24 .…”