92 D. Dörffel et al.: J Extra Corpor Technol 2025, 57, 89 – 95
Figure 2. Scatterplot of the age of patients relative to the hematocrit of the processed blood in %.
In 182 cases, the target value for the hematocrit of the autotransfusion blood was achieved. Of these, 63 % were men and 37 % were women, which roughly corresponds to the gender distribution of the entire cohort( 65 % men, 35 % women). The mean age of this group was 63 and the median was 69. In 52 cases( 22 %), the hematocrit of the autotransfusion blood was 50 %. The proportion of men was 71 % and that of women 29 %. The mean age was 67, and the median age was 70. No significant correlation was observed between the patient age and the hematocrit value in the processed blood( two-sided p = 0.186 by Spearman correlation). The correlation between patient age and the level of hematocrit in the processed blood is shown in a scatterplot, which also indicates no obvious correlation( shown in Fig. 2). Therefore, the patient’ s age did not significantly influence the hematocrit. There was also no significant correlation between the patient’ s gender and the level of hematocrit in the processed blood( p = 0.288 by Phi coefficient). Of the 234 cases in which the hematocrit value was available in the autotransfusion blood, a surgical diagnosis was given in 200 cases. The correlation between the surgical diagnosis and compliance with the hematocrit target was not significant( p = 0.147 by Cramer V). The distribution of hematocrit in the processed blood did also not differ significantly between the categories of surgical diagnosis( p = 0.078 by Kruskal-Wallis-Test). Therefore, there was no significant influence of the surgical diagnosis on the hematocrit value.
Elimination of total protein
The distribution of total protein elimination is shown in the histogram( shown in Fig. 3). The minimum total protein elimination was 57.5 %, and the maximum was 99.9 %. The arithmetic mean was 95.24 %, and the median was 96.13 %, both of which are within the prescribed target value of 90 %. The total protein elimination values were not normally distributed. In 11 cases, the target value could not be achieved, corresponding to approximately 8.5 %. In the cases where the target value
was not reached, the mean age was 65 and the median age was 70, which is slightly higher than in the group that reached the target value( mean age 60, median age 65). No significant correlation was observed between the patient age and the total protein elimination( two-sided p = 0.159 by Spearman correlation). The correlation between patient age and total protein elimination is shown in a scatter plot, which also indicates no obvious correlation( shown in Fig. 4). In the group that did not meet the target value, the proportion of male patients was higher, corresponding to 91 %. In all cases, regardless of the total protein elimination, the proportion of male patients was around 63 %. The Phi coefficient of �0.175 indicates a slight significant correlation between gender and reaching the target value( p = 0.046). However, this difference may also be due to the small number of cases in which the target value for total protein elimination was not reached. There was no significant difference in hematocrit distribution of protein elimination between surgical diagnoses( p = 0.5 by Kruskal-Wallis-Test). Consequently, we conclude that surgical diagnosis did not have a significant impact on total protein elimination.
Discussion
Previous clinical studies have not explicitly investigated the influence of patient age, gender, and surgical diagnosis on compliance with the target values for intraoperative cell salvage. This may be because Germany is one of the few countries that have defined target values for intraoperative cell salvage. In this retrospective data analysis conducted at the Charité, it was shown that the target values for hematocrit in autotransfusion blood(> 50 %) and for total protein elimination(> 90 %) are not always achieved when intraoperative cell salvage is used. The target hematocrit value was not achieved in around 22 % of the cases included. The total protein elimination did not fulfill the target value in 8.5 % of cases. The age and gender of the patient and the surgical diagnosis have little to no influence on compliance with the target values.