 in 1981 to 95% in 2002 (P < 0.001). In 1981, 22% of the respondents replied that they had used acute normovolemic hemodilution; in 2002, 31% indicated that they had used the technique within the previous 12 months.
In 1981, 46% of respondents did not know whether a maximum surgical blood-ordering schedule (MSBOS) was used in their primary hospital; 52% did not know in 2002 (P
= 0.114). The use of a type and screen without crossmatch before surgical procedures in which transfusion might be required increased from 65% in 1981 to 87% in 2002 (P
< 0.001). The percentage of anesthesiologists who require patients undergoing elective surgery to have a hemoglobin concentration of at least 10 g/dl decreased from 65% in 1981 to 9% in 2002 (P
< 0.001). Table 3
shows that there were statistically significant differences in transfusion practices for all of the four case scenarios.
shows that the responses to the methods used for estimating blood loss during major abdominal surgery changed from 1981 to 2002. Measuring the contents of suction containers decreased from 95% in 1981 to 91% in 2002 (P
= 0.01). Visual estimation decreased from 88% in 1981 to 82% in 2002 (P
= 0.005). Use of serial hemoglobin and/or hematocrit determinations increased from 45% in 1981 to 81% in 2002 (P
< 0.001). Weighing sponges decreased from 48% in 1981 to 26% in 2002 (P
In the 1981 survey, erythrocytes were reported to be transfused by 15% of respondents only if vital signs changed (i.e., blood pressure decreased, pulse rate increased significantly). In 2002, 52% relied primarily on vital signs (P < 0.001). One third of anesthesiologists in 2002 transfused before estimated blood loss approached 20% of estimated blood volume; 42% used this criterion in 1981 (P = 0.002). A response indicating transfusion of erythrocytes to adults only if more than 1 U is required changed from 18% in 1981 to 12% in 2002 (P = 0.002). In 2002, 13% indicated that allogeneic whole blood was available in their institutions. Sixty-one percent of respondents to the 2002 survey indicated that they used the same criteria for reinfusion of preoperatively donated autologous blood as for allogeneic blood, whereas 38% transfused autologous blood more liberally.
The reported practice of reconstituting or diluting erythrocytes with crystalloid (vast majority using normal saline) increased from 69% in the 1981 survey to 87% of respondents in the 2002 survey (P < 0.001). This practice was performed to decrease the viscosity of the erythrocyte units. The use of micropore filters for all erythrocyte transfusions increased from 37% in 1981 to 60% in 2002 (P < 0.001). Use of blood warmers for all erythrocyte transfusions increased from 48% in 1981 to 89% in 2002 (P < 0.001).
The primary indications for requesting that platelets be available were a platelet count below a specified value and surgical procedures usually associated with significant blood loss. In 1981, 80% replied that they requested platelets to be available in the first situation, specifying a mean platelet count of 68 × 109/l. In 2002, 89% of the respondents requested that platelets be available for patients with a mean platelet count of 74 × 109/l (P < 0.001) and significant anticipated blood loss. In 1981, 33% requested that platelets be available if more than one blood volume replacement was required; 56% responded similarly in 2002 (P < 0.001).
A question regarding platelet transfusion practices, which had response choices based on the ASA Guidelines, was added to the 2002 survey (question 10, Appendix 2
). Fifty-five percent of respondents would transfuse platelets prophylactically in a patient with idiopathic thrombocytopenic purpura and a platelet count of 20 × 109
/l, although the ASA Guidelines state that prophylactic platelet transfusion is ineffective and rarely indicated in patients with idiopathic thrombocytopenic purpura. Platelets would have been transfused by 51% of anesthesiologists in 2002 to patients with microvascular bleeding and platelet counts less than 100 × 109
/l. Thirty-three percent would have transfus