Changes in the blood endotoxin concentration after digestive surgery

Systemic endotoxin activity correlates with clot formation: an observational study in patients with early systemic inflammation and sepsis

Introduction

Inflammation and coagulation are closely linked, and both can be triggered by endotoxin. Thrombelastometry and impedance aggregometry are of diagnostic and predictive value in critically ill patients. In this observational study we investigated the correlation of endotoxin activity with thrombelasometric and aggregometric variables in patients with systemic inflammation.

Methods

Based on a daily screening on a tertiary academic surgical ICU, patients, as soon as they fulfilled two or more criteria for systemic inflammatory response syndrome (SIRS), were included. In whole blood we performed endotoxin activity (EA) assay, thrombelastometry (ROTEM^®) and impendance aggregometry (Multiplate^®).

Results

In total, 49 patients were included with a broad spread of EA levels of (median (minimum to maximum)) 0.27 (0.01 to 0.72), allowing expedient correlative analysis. Clot formation time (CFT) (263 s (60 to 1,438 s)) and clotting time (CT) (1,008 s (53 to 1,481 s)) showed a significant negative correlation with EA level (r = -0.38 (P < 0.005) and r = -0.29 (P < 0.05)). Positive correlations were found for alpha-angle (50° (17 to 78°), r = 0.40 (P < 0.005)) and maximum clot firmness (MCF) (55 mm (5/76), r = 0.27 (P < 0.05)). No significant correlations were found between Lysis Index at 60 minutes (LI60) and EA levels. There was no correlation between EA level and aggregometric values, or classical coagulation parameters.

Conclusions

In patients with systemic inflammation, increasing endotoxin concentrations correlate with increased clot formation.

Effect of major abdominal surgery on endotoxin release and expression of Toll-like receptors 2/4

BACKGROUND

Surgery can cause endotoxemia, and endotoxin aggregates to Toll-like receptors and acts proinflammatory; repetitive endotoxin application can cause tolerance. The objective of the study is to characterize early inflammatory response and expression of TLR2/4 during major abdominal surgery.

MATERIALS AND METHODS

A prospective controlled study of 20 patients with elective major abdominal surgery was performed. Blood samples were collected before and at a defined time after surgery. Endotoxemia, capability of plasma to inactivate endotoxin, cytokine release of LPS-stimulated mononuclear cells, quantitative TLR mRNA expression, and plasma concentrations of TNFalpha, IL-6, C-reactive protein (CRP), alpha(1)-acid glycoprotein, transferrin, and albumin were measured.

RESULTS

Surgery caused endotoxemia (p = 0.053), and the capability of plasma to inactivate endotoxin was reduced (p = 0.0002). Two hours postoperatively, the plasma concentrations of TNFalpha and IL-6 peaked significantly, but the liberation capacity of mononuclear cells for cytokines (TNFalpha, IL-1beta, IL-6) was significantly reduced. The concentration of CRP and alpha(1)-acid glycoprotein peaked 48 h postoperatively, but those of transferrin and albumin were significantly decreased (p < 0.001, respectively). Median mRNA expression of TLR2 and TLR4 of mononuclear cells was not altered, and there was no obvious trend over time.

CONCLUSION

Major abdominal surgery is associated with endotoxemia, reduced capability of plasma to inactivate endotoxin, cytokine kinetics resembling those of healthy man after experimentally given LPS, and substantial acute-phase reaction. The cytokine liberation of mononuclear cells suggests a state of postoperative endotoxin tolerance. Despite these substantial changes, trends in TLR2/4 expression are not obvious.

Clinical laboratory differentiation of infectious versus non-infectious systemic inflammatory response syndrome

OBJECTIVE

To evaluate the accuracy of C-reactive protein (CRP), procalcitonin (PCT), neopterin, and endotoxin in the differential diagnosis of sepsis and non-infectious systemic inflammatory response syndrome (SIRS).

METHODS

A Medline database and references from identified articles were used to perform a literature search relating to the differential diagnosis of sepsis versus non-infectious SIRS.

RESULTS

CRP, PCT, and neopterin are released both in sepsis and in non-infectious inflammatory disease. CRP and PCT are equally effective, although not perfect, in differentiating between sepsis and non-infectious SIRS. However, CRP and PCT have different kinetics and profiles. The kinetics of CRP is slower than that of PCT, and CRP levels may not further increase during more severe stages of sepsis. On the contrary, PCT rises in proportion to the severity of sepsis and reaches its highest levels in septic shock. PCT tends to be higher in nonsurvivor than in survivor. Therefore, PCT demonstrated a closer correlation with the severity of sepsis and outcome than CRP. Unlike CRP and PCT, neopterin is increased in viral infection as well as bacterial infection, and neopterin is also a useful indicator of sepsis. Endotoxemia was detected in no more than half of patients with Gram-negative bacteremia, and Gram-negative bacteremia was detected in half of patients with endotoxemia.

CONCLUSIONS

The diagnostic capacity of PCT is superior to that of CRP due to the close correlation between PCT levels and the severity of sepsis and outcome. Neopterin is very useful in the diagnosis of viral infection. The endotoxin assay in combination with CRP, PCT, or neopterin may help as a diagnostic marker for Gram-negative bacterial infection.

Methodological studies on plasma endotoxin level and endotoxin inactivation capacity

To establish stable methods for detecting plasma endotoxin level and endotoxin inactivation capacity in a normal population and general surgical patients and evaluate their perioperative changes. 50 healthy people and 50 patients receiving gastrointestinal operation were enrolled, their plasma endotoxin levels and plasma endotoxin inactivation capacity were assayed. Our results showed that plasma endotoxin levels were 0.044 +/- 0.009 EU/ml in the normal population and 0.044 +/- 0.023 EU/ml in the preoperative patients. Endotoxin level peaked 3 h after the operation (0.223 +/- 0.041 EU/ml), and then decreased rapidly on the first day after the operation (0.134 +/- 0.164 EU/ml). Endotoxin inactivation capacity also had the same time course as endotoxin level. Systemic inflammatory response syndrome and infection induced another elevation in the time course. It is concluded that establishing the endotoxin standard curve by using pyrogenic free water is better than by using plasma. Plasma endotoxin inactivation capacity can be used as an indirect indicator of postoperative immune depression. Plasma endotoxin level and endotoxin inactivation capacity peaked shortly after operation, indicating surgical stress is closely related with the changes.

Influence of modest endotoxemia on postoperative antithrombin deficiency and circulating secretory immunoglobulin a levels

OBJECTIVE

To evaluate the influence of modest endotoxemia on postoperative antithrombin deficiency and cholestasis.

SUMMARY BACKGROUND DATA

It has not been determined whether endotoxin translocation in small amounts is a physiological phenomenon or whether it is a potential health hazard.

METHODS

Blood endotoxin, antithrombin III (ATIII), secretory immunoglobulin A (sIgA), which was selected as a marker of cholestasis, C-reactive protein (CRP), and alpha-1-antitrypsin (AAT) concentrations were measured from the 20 patients undergoing curative gastrectomy for gastric cancer preoperatively and postoperatively. Portal and systemic blood samples were taken for the analysis of endotoxin and interleukin-6 (IL-6) concentrations during surgery in these patients.

RESULTS

Although plasma endotoxin levels showed a significant increase during surgery, we did not find a correlation with ATIII, sIgA, CRP, and IL-6 levels. Systemic blood endotoxin levels during surgery correlated with a postoperative rise of serum AAT levels. Plasma ATIII levels transiently decreased on the first and third postoperative day, and sIgA levels were shown to increase on the seventh postoperative day. There was a weak relationship between the extent of postoperative endotoxemia and a reduction in ATIII concentrations.

CONCLUSIONS

The influence of modest endotoxemia on postoperative antithrombin deficiency and cholestasis was limited, and increased translocational endotoxemia during abdominal surgery may be a physiological phenomenon to trigger off an acute-phase protein response.

Endotoxemia and acute-phase proteins in major abdominal surgery

BACKGROUND

Translocation of endotoxin is a controversial issue. The ability of plasma to inactivate endotoxin is an indirect measure of endotoxemia. Endotoxin is a potent stimulator of the inflammatory response and affects the innate immune system.

OBJECTIVE

To elucidate the kinetics of endotoxemia and the ability of plasma to inactivate endotoxin in patients with major abdominal operations. To demonstrate the early time course of the acute-phase proteins C-reactive protein (CRP), serum amyloid A (SAA), alpha(1)-antitrypsin, alpha(2)-macroglobulin, transferrin, and interleukin 6 (IL-6), and to correlate them with the amount of endotoxemia.

METHODS

Twenty patients with elective major abdominal operation and 10 healthy controls were investigated. Blood was collected preoperatively, during the operation and regularly up to 12 days after surgery. Endotoxin was measured by Limulus amebocyte lysate test (LAL), the ability of plasma to inactivate endotoxin by modified LAL, the acute-phase proteins nephelometrically, and IL-6 by enzyme-linked immunosorbent assay (ELISA).

RESULTS

Preoperative endotoxin plasma level (0.026 +/- 0.004 EU/mL) did not differ from healthy volunteers but increased during operation (0.09 +/- 0.02 EU/mL, P = 0.02). Endotoxemia peaked 1 hour after the surgical procedure (0.16 +/- 0.03 EU/mL; P <0.0001 versus preoperative) and decreased to almost normal values after 48 hours. The capability of plasma to inactivate endotoxin was significantly reduced during (recovery, 0.16 +/- 0.03 EU/mL), 1 hour (0.25 +/- 0.04 EU/mL) and 24 hours (0.16 +/- 0.02 EU/mL) after the operation compared with preoperative (0.068 +/- 0.01 EU/mL) values. Plasma IL-6 was significantly increased for 48 hours with a peak 1 hour after surgery (470 +/- 108 pg/mL). CRP peaked at 210 +/- 19 mg/L (P <0.0001 versus preoperative) 48 hours after operation and was significantly elevated for the rest of the observation period. SAA was significantly increased 24 hours after surgery (249 +/- 45 mg/L) and peaked additional 48 hours later (456 +/- 86 mg/L). alpha(1)-Antitrypsin, although a positive acute-phase protein, decreased initially to 1.38 +/- 0.1 g/L (preoperative, 2.33 +/- 0.18 g/L; P <0.0001) and increased thereafter until day 12 (3.05 +/- 0.35 g/L, P = 0.11 versus preoperative). The same was true for alpha(2)-macroglobulin (preoperative, 2.2 +/- 0.16 g/L; intraoperative, 1.36 +/- 0.13 g/L; day 5, 2.8 +/- 0.4 g/L). Transferrin decreased already during surgery (1.6 +/- 0.1 g/L versus preoperative 2.8 +/- 0.17 g/L, P <0.0001) and remained on this level for 5 days. Correlation analysis revealed a relationship between endotoxemia and the ability of plasma to inactivate endotoxin (r = 0.67, P <0.0001) and also a relation between intraoperative endotoxemia on one hand and alpha(2)-macroglobulin (-0.53 > r > -0.6, P <0.05) as well as alpha(1)-antitrypsin (0.64 > r >0.55, P <0.05) on the other.

CONCLUSION

Major abdominal surgery is associated with transient endotoxemia and a transient reduced endotoxin inactivation capacity of the plasma. Endotoxemia correlates with the endotoxin inactivation capacity. The surgical procedure causes substantial changes in plasma concentrations of acute-phase proteins. alpha(2)-Macroglobulin and alpha(1)-antitrypsin correlate moderately with endotoxemia.

Translocation of endotoxin and acute-phase proteins in malleolar fractures

BACKGROUND AND OBJECTIVE

Translocation of endotoxins was demonstrated for multiple injury but not for minor trauma such as isolated malleolar fractures. Major trauma leads to substantial changes in the plasma concentration of acute-phase proteins. However, isolated malleolar fractures are minor trauma. The objective of this study was to elucidate the kinetics of endotoxemia and the ability of plasma to inactivate endotoxin of patients operated on malleolar fractures and to demonstrate the early time course of the acute-phase proteins C-reactive protein, transferrin, alpha1-acid glycoprotein, haptoglobin, and interleukin-6 and to correlate them with the amount of endotoxemia.

METHODS

Thirty patients with malleolar fractures were operated on within 6 hours after injury. Blood was collected immediately after admission and regularly up to 96 hours after surgery.

RESULTS

Preoperative endotoxin plasma levels were increased compared with that of healthy individuals (0.05 +/- 0.017 vs. 0.02 EU/mL). Endotoxemia peaked 0.5 hours after the surgical procedure at 0.096 +/- 0.03 (p < 0.05 vs. healthy) and decreased to almost normal values after 24 hours. The ability of the plasma to inactivate endotoxin was significantly reduced after the surgical procedure compared with normal subjects (recovery, 0.17 +/- 0.028 EU/mL vs. 0.04 +/- 0.01 EU/mL; p < 0.05). Plasma interleukin-6 peaked 0.5 hours postoperatively (114 +/- 11 pg/mL, p < 0.05 vs. healthy), decreasing thereafter. C-Reactive protein peaked at 45 +/- 5 mg/mL (p < 0.05) 48 hours after injury. Transferrin decreased significantly postoperatively (2.41 +/- 0.12 mg/mL vs. pre-OP 2.65 +/- 0.1 mg/mL) and remained on this level for 96 hours. Both, alpha1-acid glycoprotein and haptoglobin increased postoperatively until day 4 (0.78 +/- 0.06 mg/mL to 1.15 +/- 0.08 mg/mL and 1.51 +/- 0.12 mg/mL to 3.24 +/- 0.22 mg/mL). There was no correlation between endotoxemia and the concentrations of the acute-phase proteins and interleukin-6.

CONCLUSION

Surgery for malleolar fractures is associated with temporary endotoxemia and temporary reduced endotoxin inactivation capacity of the plasma. The injury and the surgical procedure leads to substantial changes in the plasma concentrations of acute-phase proteins. The relation between endotoxemia and acute-phase response is not dose dependent.

(1-->3)-beta-D-glucan determination in rat organs with limulus coagulation factor G

One cause of a false positive limulus test after surgery or hemodialysis has been identified as extrinsic (1-->3)-beta-D-glucan which was derived from surgical gauze or cellulose dialyzer. However, there have been no investigations concerning intrinsic factors and the presence of (1-->3)-beta-D-glucan in mammalian organs. In this study, (1-->3)-beta-D-glucan in homogenate of various rat organs and stool was measured by a Gluspecy test (G test) using factor G, which specifically reacts with (1-->3)-beta-D-glucan. In small intestine and lung, large amounts of factor G-activating substance were observed and identified as (1-->3)-beta-D-glucan by a digestion study using end-(1-->3)-beta-D-glucanase. However, only very small amounts of (1-->3)-beta-D-glucan were found in the kidney, spleen, vena cava, aorta, thymus, heart and liver. In serum and plasma, no (1-->3)-beta-D-glucan was observed. On the other hand, extremely large amounts of (1-->3)-beta-D-glucan were found in stool. Minute amounts of (1-->3)-beta-D-glucan were observed in a variety organs except for the small intestine and lung. High levels of (1-->3)-beta-D-glucan found in the small intestine might be traced to contamination by stool in the small intestine, and such levels in the lung might derive from macrophages which have trapped (1-->3)-beta-D-glucan in the air.

Clinical and experimental studies of the limulus test after digestive surgery

A chromogenic limulus test (Toxicolor test) revealed a transiently increased blood endotoxin level in some patients after digestive surgery. However, most showed no clinical signs of endotoxemia. The Endospecy test of these specimens, which reacts specifically with endotoxin, did not show a high value, while the Gluspecy test, which reacts specifically with (1-->3)-beta-D-glucan (glucan), did. These findings thus suggested that the gauze used for surgery contains a large amount of glucan. The intraperitoneal injection of this gauze-saline into rats results in a phenomenon similar to that observed in clinical studies. These findings suggested the involvement of substances other than endotoxin such as glucan in the postoperative positive-Toxicolor phenomenon. In addition, the Toxicolor test also showed a higher value in patients with liver cirrhosis than in those without. In an experimental study in rats, the liver cirrhosis group also showed a significantly high value. These results therefore suggest that the glucan clearance mechanism is impaired in the reticuloendothelial system in liver damage such as cirrhosis.

Endotoxemia: methods of detection and clinical correlates

As an assay for endotoxin, the Limulus amebocyte lysate assay has several desirable properties: sensitivity, specificity, and potential for adaptation to a quantitative format. Several modifications have been developed to enhance its potential for clinical application. The modifications that allow quantitative measurement of endotoxin and also improve its application to blood samples are described in this review. In fluids other than blood, the detection of endotoxin with the Limulus amebocyte lysate assay can be used as an aid to identify the presence of gram-negative bacteria, and the assay has established utility. With blood, however, there are a range of factors that interfere with the detection of endotoxemia and there are disparate views with respect to the diagnostic and prognostic significance of the test results. In general, the clinical significance of the finding of endotoxemia broadly parallels the frequency and importance of gram-negative sepsis in the patient groups studied and a decline in endotoxin levels accompanies clinical improvement. However, with therapies designed to reduce levels of endotoxin, or to antagonize its effects, it is unclear whether clinical improvement occurs as a consequence of changes in the levels of endotoxemia.

The fate of intravenously injected endotoxin in normal rats and in rats with liver failure

The elimination of endotoxin from the blood was studied in rats with D-galactosamine-induced liver failure and in normal controls after intravenous injection of various doses of endotoxin. Endotoxin was found to localize in liver tissue by immunohistochemical staining with factor C, which is derived from amebocyte lysate of the horseshoe crab and which reacts specifically with endotoxin. Before injection, the blood endotoxin concentrations were normal both in control rats and in rats with liver failure. The blood concentrations of endotoxin were significantly higher after intravenous injection of endotoxin in the D-galactosamine-induced liver failure group (p < 0.05) and decreased much more slowly (p < 0.05). Endotoxin concentrations were also significantly higher after in vitro incubation with plasma from rats with liver failure (p < 0.05). After intravenous injection of endotoxin (1 mg/kg), endothelial and Kupffer cells in the liver sinusoids were positively stained for endotoxin in the control group, but not stained or faintly stained in the liver failure group. Endotoxemia in liver failure thus results from reduced inactivation of endotoxin in plasma and from impaired hepatic clearance.