Comparative evaluation of extracellular mass and body cell mass between patients with SIRS and severe sepsis by bioelectrical impedance analysis

Introduction

The present study compares the changes of extracellular mass (ECM) and body cell mass (BCM) in patients with SIRS and severe sepsis with the aid of bioelectrical impedance analysis.

Methods

In the study, 32 mechanically ventilated SIRS patients were included. The total body water balance and nitrogen balance (NB) were evaluated everyday. ECM and BCM were measured in kilograms, by bioelectrical impedance analysis at the first and 10th ICU hospitalisation day. On the second measurement, 12 patients (SIRS group) remained in SIRS with stable health status or improvement, while 18 patients had severe sepsis (SEPSIS group). Differences between the first and second measurement were expressed as ΔECM and ΔBCM. Alterations of all studied parameters were compared between the two groups with the student paired t test (P < 0.05).

Results

BCM was significantly reduced from 23.7 ± 7.21 to 19.0 ± 7.01 (P = 0.048). The reduction in the SEPSIS group was insignificant (from 21.8 ± 6.28 to 20.3 ± 5.74, P = 0.252). The difference between the corresponding changes was not significant (P = 0.2180).

ECM decreased non-significantly in the SIRS group (from 36.6 ± 9.91 to 35.3 ± 7.88, P = 0.666). On the contrary, ECM increased significantly in the SEPSIS group (from 37.7 ± 11.94 to 49.2 ± 13.09, P < 0.0001). Changes of ECM differed significantly between the two groups (P = 0.0011). The total body water balance in the SIRS group (602.9 ± 2938.85) was significantly lower than in the SEPSIS group (12,779.4 ± 8025.75) (P < 0.0001). The NB was negative in both groups (SIRS: 1.5 ± 3.74; SEPSIS: 4.3 ± 4.23), but their difference was not significant (P = 0.7308).

Conclusions

The present study shows that BCM and NB follow a similar reduction pattern in both groups, although it is not correlated. This finding could be related to the multivariate influence on BCM (catabolism, immobilization, medication). It seems that ECM changes reflect the process of the disease since it decreased in the rather stable SIRS group and increased in the deteriorating SEPSIS group.