Peripheral oedema may not reflect capillary leak in severe sepsis: pilot study

Objectives

Whether systemic capillary leak can be monitored or whether it exists at all remains controversial [1]. The aim of this study was to investigate the origin of peripheral oedema in patients with severe sepsis.

Materials and methods

Ten patients fulfilling the severe sepsis criteria [2], requiring mechanical ventilation, and having a high (> 2 mm) oedema score were recruited [3], and observed daily, for 3 days. Subcutaneous oedema fluid (5 ml) was drained from the patients' back of the hand using a special, perforated 20G intravenous cannula once a day. At the same time arterial blood and urine were collected (5 and 10 ml, respectively). From oedema and blood samples total protein, albumin and inflammatory markers (PCT, CRP, tumour necrosis factor alpha, IL-6, IL-8), and from urine microalbuminuria (MCR) levels were determined. Oedema was considered due to capillary leak if the oedema protein (TPoe)/serum total protein (TPs) ratio ≥ 0.65, and hydrostatic if < 0.65 [4]. Data are presented as the mean ± standard deviation, or the median and interquartile range (IQR) according to the data distribution.

Results

In addition to clinical signs, all patients proved to be septic as indicated by high inflammatory marker levels (Table 1). Increased capillary leak was suggested by high oedema score, 3.3 ± 0.6 mm, and elevated MCR. However, the TPoe/TPs ratio was 0.21 ± 0.16, indicating mainly hydrostatic forces as a reason for peripheral oedema.

Table 1

Discussion

To our knowledge this is one of the first studies to address the question of the origin of the oedema fluid in severe sepsis. The low TPoe/TPs ratio found indicates mainly hydrostatic forces in oedema formation. These preliminary results suggest that, despite evidence of severe sepsis, the diagnosis of 'increased capillary leak' cannot be made on the basis of the clinical signs of severe peripheral oedema.