The effect of a hemofilter during extracorporeal circulation on hemodynamics in patients with SIRS

Extracorporeal Therapies in the Treatment of Sepsis: Experience and Promise

Desire to restore the balance of body elements has enamored physicians since the ancient practice of bloodletting. More recently, extracorporeal techniques have been employed in both adults and children in treating sepsis. Extracorporeal therapies include continuous renal replacement (CRRT), plasma-based removal techniques, and extracorporeal membrane oxygenation (ECMO). These treatments could theoretically 1) provide immunohomeostasis of pro- and anti-inflammatory cytokines and other sepsis mediators, 2) decrease organ microthrombosis through removal of pro-coagulant factors and modulating the impaired septic coagulation response in sepsis, and 3) provide mechanical support of organ perfusion during the acute septic episode to allow time for response to traditional sepsis therapies and antimicrobials. CRRT is beneficial in managing fluid overload and acute renal failure in sepsis. Removal of sepsis mediators through the technique is variable, and the outcome impact of CRRT on sepsis has not been definitively determined. High-flow CRRT has demonstrated benefit in septic adults. Intriguing early results suggest that plasma exchange could improve outcomes in both adults and children. Based on experience, ECMO is recommended for refractory septic shock in neonates and should be considered for use in children. Ongoing trials may help determine whether the promise of extracorporeal therapies translates into outcome improvement in septic children.

Amelioration of hemodynamics and oxygen metabolism by continuous venovenous hemofiltration in experimental porcine pancreatitis

AIM: To investigate the potential role of continuous venovenous hemofiltration (CVVH) in hemodynamics and oxygen metabolism in pigs with severe acute pancreatitis (SAP).

METHODS: SAP model was produced by intraductal injection of sodium taurocholate [4%, 1 mL/kg body weight (BW)] and trypsin (2 U/kg BW). Animals were allocated either to untreated controls as group 1 or to one of two treatment groups as group 2 receiving a low-volume CVVH [20 mL/(kg.h)], and group 3 receiving a high-volume CVVH [100 (mL/kg.h)]. Swan-Ganz catheter was inserted during the operation. Heart rate, arterial blood pressure, cardiac output, mean pulmonary arterial pressure, pulmonary arterial wedge pressure, central venous pressure, systemic vascular resistance, oxygen delivery, oxygen consumption, oxygen extraction ratio, as well as survival of pigs were evaluated in the study.

RESULTS: Survival time was significantly prolonged by low-volume and high-volume CVVHs, which was more pronounced in the latter. High-volume CVVH was significantly superior compared with less intensive treatment modalities (low-volume CVVH) in systemic inflammatory reaction protection. The major hemodynamic finding was that pancreatitis-induced hypotension was significantly attenuated by intensive CVVH (87.4±12.5 kPa vs 116.3±7.8 kPa, P<0.01). The development of hyperdynamic circulatory failure was simultaneously attenuated, as reflected by a limited increase in cardiac output, an attenuated decrease in systemic vascular resistance and an elevation in oxygen extraction ratio.

CONCLUSION: CVVH blunts the pancreatitis-induced cardiovascular response and increases tissue oxygen extraction. The high-volume CVVH is distinctly superior in preventing sepsis-related hemodynamic impairment.

Effect of Hemodiafiltration on Pulmonary Hemodynamics in Endotoxic Shock

Hemofiltration can improve pulmonary hemodynamics during septic shock. The main objective of the study was to determine whether hemodiafiltration (HDF) would also have beneficial effects on pulmonary hemodynamics during septic shock. In the Endo group, six anesthetized pigs received a 0.5 mg/kg endotoxin infusion over 30 min. In the HDF group (n = 6), HDF was started 30 min after the end of the endotoxin infusion, while in the Control group (n = 4) they received HDF but no endotoxin infusion. Pulmonary hemodynamics were analyzed in detail with a four-element windkessel model. Although in the Control group, HDF did not alter pulmonary hemodynamic parameters, in the HDF group, it was responsible for an amplification of the deleterious pulmonary vascular response to endotoxin insult. Our results show that HDF must be used cautiously in septic shock since it can precipitate right heart failure by increasing pulmonary vascular resistance.

Effects of direct hemoperfusion with a beta2-microglobulin adsorption column on hypercytokinemia in rats

BACKGROUND/AIM

Blood purification therapies have been clinically applied to treat the cytokine-induced pathological responses. The effects of direct hemoperfusion(DHP) with a beta(2)-microglobulin (BMG) adsorption column on hypercytokinemia were investigated.

METHODS

A hypercytokinemia model was prepared by injecting lipopolysaccharide (LPS) into femoral veins of male Wistar rats weighing 250-400 g. The hypercytokinemic rats were connected to the DHP system using a small BMG adsorption column, and time course changes in plasma levels of inflammatory cytokines were then examined.

RESULTS

Plasma levels of interleukins (IL) 1beta and 6 and tumor necrosis factor alpha (TNF-alpha) were found to be significantly elevated within 3 h after LPS injection in the control group that underwent extracorporeal circulation without the BMG adsorption column, whereas the increases in plasma levels of IL-6 and TNF-alpha were significantly inhibited in the group that was treated with the BMG adsorption column. The adsorption rates of cytokines with the BMG adsorption column were 20-40% for IL-1beta and IL-6 and 10-85% for TNF-alpha during treatment for 3 h.

CONCLUSIONS

These results suggest that the systemic inflammatory response syndrome with hypercytokinemia might be treated with DHP using the BMG adsorption column.

Acute renal failure in the ICU: assessing the utility of continuous renal replacement

Acute renal failure (ARF) in the ICU patient still remains a common problem and is associated with increased morbidity, mortality, and cost. Potential advantages of continuous renal replacement (CRRT), compared with intermittent hemodialysis (IHD) include enhanced hemodynamic stability, increased solute removal, and greater ultrafiltration. Although it was hoped that CRRT would lead to improvement in patient outcomes, there are few prospective, randomized clinical studies comparing this modality with conventional hemodialysis in the treatment of patients with ARF. The difficulties associated with designing such prospective studies are the complex status of the medical patients and the ethical dilemma of randomizing patients to a certain dialysis modality. At this time, there is no evidence to support the assertion that CRRT improves clinical outcomes compared with IHD.