O. Thuemer

Increasing cardiac output by fluid loading: effects on indocyanine green plasma disappearance rate and splanchnic microcirculation

Background:  Sufficient cardiac pre‐load for maintaining adequate cardiac output is a major goal in the treatment of critically ill patients. We studied the effects of increasing cardiac output by fluid loading on the indocyanine green plasma disappearance rate (ICG‐PDR) and gastric mucosal regional CO2 tension (PRco2) as an indicator of splanchnic microcirculation.

The Influence of Venovenous Renal Replacement Therapy on Measurements by the Transpulmonary Thermodilution Technique

BACKGROUND:Use of the transpulmonary thermodilution technique has been suggested for extended hemodynamic monitoring in critically ill patients. However, many of these patients also require renal replacement therapy (RRT). Therefore, we analyzed the influence of venovenous RRT on measurement of cardiac index (CI), intrathoracic blood volume index (ITBVI), and extravascular lung water index (EVLWI). METHODS:We studied 24 consecutive critically ill patients (15 males, 9 females; age 39–81, mean 62 yr) who had received a clinically indicated 5F femoral arterial catheter (PV2015L20, Pulsion Medical Systems, Germany), which was connected to a monitor (PiCCOplus, Pulsion Medical Systems, Germany). A 12F dialysis catheter (Trilyse Expert, Vygon) was either advanced from the vena femoralis into the vena cava inferior (n = 12) or placed into the superior vena cava (n = 12). Patients continuously received heparin for anticoagulation. Hemodynamic measurements were performed in triplicate by central venous injection of saline (15 mL, <8°C) during RRT, during a brief interruption in RRT (by disconnection, without retransfusion), and immediately after reconnection. Ventilator settings, fluid status, and vasoactive drugs remained unchanged. RESULTS:RRT was associated with significant changes in CI (mean change, −0.1 L/min/m2, P = 0.003) and ITBVI (mean change, −18 mL/m2, P = 0.02), whereas EVLWI was unaffected (mean change, +0.1 mL/kg, P = 0.42). The influence of RRT on CI, ITBVI, and EVLWI was not statistically different in both subgroups. CONCLUSIONS:RRT had no clinically relevant effect on measurement of CI, ITBVI, and EVLWI in patients with sepsis and maintained cardiac output. Furthermore, the dialysis catheter tip position had no significantly different influence under these conditions.

Positive end-expiratory pressure does not affect indocyanine green plasma disappearance rate or gastric mucosal perfusion after cardiac surgery

Background and objective: Positive end‐expiratory pressure (PEEP) may affect hepato‐splanchnic blood flow. We studied whether a PEEP of 10 mbar may negatively influence flow‐dependent liver function (indocyanine green plasma disappearance rate, ICG‐PDR) and splanchnic microcirculation as estimated by gastric mucosal PCO2 (PRCO2). Methods: In a randomized, controlled clinical study, we enrolled 28 patients after elective cardiac surgery using cardiopulmonary bypass. In 14 patients (13 male, 1 female; age 48–74, mean 63 ± 7 yr) we assessed ICG‐PDR and PRCO2 on intensive care unit admission with PEEP 5 mbar, after 2 h with PEEP of 10 mbar and again after 2 h at PEEP 5 mbar. Inspiratory peak pressure was adjusted to maintain normocapnia. Fourteen other patients (8 male, 6 female; age 46–86, mean 68 ± 11 yr) in whom PEEP was 5 mbar throughout served as controls. All patients underwent haemodynamic monitoring by measurement of central venous pressure, left atrial pressure and cardiac index using pulmonary artery thermodilution. Results: While doses of vasoactive drugs and cardiac filling pressures did not change significantly, cardiac index slightly increased in both groups. ICG‐PDR remained unchanged either within or between both groups (PEEP10 group: 24.0 ± 6.9, 22.0 ± 7.9 and 25.5 ± 7.7% min−1 vs. controls: 22.0 ± 7.5, 23.8 ± 8.4 and 21.4 ± 6.5% min−1) (P = 0.05). The difference between PRCO2 and end‐tidal PCO2 (PCO2‐gap) did not change significantly (PEEP10 group: 1.1 ± 0.9, 1.3 ± 0.7 and 1.3 ± 0.9 kPa vs. controls: 0.8 ± 0.5, 0.9 ± 0.5 and 0.9 ± 0.5 kPa). Conclusion: A PEEP of 10 mbar for 2 h does not compromise liver function and gastric mucosal perfusion in patients after cardiac surgery with maintained cardiac output.

Effects of PEEP on liver function and splanchnic microcirculation: A-630

tol 20% 1.5 ml kg 1 (group M) or normal saline 1.5 ml kg 1 (group S) intravenously, before the performance of hepatic vascular occlusion. Venous blood malondialdehyde concentration (MDA), as an index of lipid peroxidation, was measured spectrophotometrically at selected timepoints. Results and Discussions: Patients in both groups presented with raised, compared to baseline, MDA values (p 0.05) for the period starting before the release of vascular occlusion until six days postoperatively. In patients receiving mannitol lower MDA values were observed (p 0.05) compared to group S at the end of operation. Conclusion: Mannitol might have a free radical scavenging activity for a short period after its administration to patients undergoing liver resection surgery with inflow vascular occlusion, but it does not seem to produce a sustained antioxidant effect after the end of operation. Furthermore, we could not confirm a positive impact on the postoperative clinical course of patients receiving mannitol. Reference: 1 Selzner N, Rudiger H, Graf R, Clavien P. Protective strategies against ischemic injury of the liver. Gastroenterology 2003; 125:917–36.

Changes in serum lactate, mix-venous oxygen saturation and indocyanin green plasma disappearance rate in postoperative cardio surgical patients: 12AP7-8

Anaesthesiology and Intensive Care, Friedrich-Schiller-University Jena, Jena, Germany Background and Goals: Parameters of global and regional, in particular hepato-splanchnic, blood flow may be used for guiding therapy in critically ill patients. However, regional conditions may not be adequately reflected by global parameters. In this study, we analysed changes in cardiac index (CI), mixed-venous oxygen saturation (SvO2), serum lactate, gastric mucosal PCO2 (PRCO2) and indocyanine green plasma disappearance rate (ICGPDR) in patients after cardiac surgery. Methods: With ethics approval and written consent we studied 52 patients (39 male, 13 female, age 65 10 years). All patients underwent pulmonary artery catheterisation for clinical indication. Serum lactate and SvO2 were determined by a blood gas analyser. ICG-PDR was measured by a transcutaneous system and PRCO2 by air tonometry. All parameters were determined immediately postoperatively on the ICU and 2 hours later. Linear regression was used for statistical analysis. A p 0.05 was considered statistically significant. Results: Cardiac index (2.8 0.8 vs. 3.2 0.7 l/min/m2), serum lactate (1.9 1.2 vs. 2.4 1.6 mmol/l) and PRCO2 (5.2 1.0 vs. 5.6 1.1 kPa) significantly increased during the study period while SvO2 (66 7 vs. 68 6 %) and ICG-PDR (21.4 6.9 vs. 21.8 7.4 %/min) remained unchanged. Furthermore, central venous pressure (8 3 vs. 8 4) and haemoglobin content (6.2 0.9 vs. 6.0 0.8 mmol/l) did not change significantly. However, body temperature (36.0 0.8 vs. 36.6 0.7°C) and dosages for norepinephrine (mean 0.04 vs. 0.02 g/kg/min) and epinephrine (mean 0.02 vs. 0.03 g/kg/min) changed significantly. The changes in SvO2 and CI correlated moderately (r 0.43, p 0.001). However, no correlation was found between changes in CI and ICG-PDR (r 0.07, p 0.62) and CI and lactate (r 0.37, p 0.91). The correlation between changes in CI and PRCO2 was r 0.37 (p 0.006). There was no relationship between changes in variables of global oxygen transport and regional blood flow: r 0.06 (p 0.65) for ICG-PDR / SvO2, and r 0.009 (p 0.95) for ICG-PDR / lactate. Conclusion: Changes in serum lactate, SvO2, ICG-PDR and PRCO2 do not correlate with changes in cardiac index and also changes within regional parameters are not reflected by each other. Thus it is not possible to draw definite conclusions from one to the other parameters.

Influence of running veno-venous renal replacement therapy on transpulmonary thermodilution: A-766

Department of Anesthesiology and Intensive Care Medicine, Friedrich-Schiller-University, Jena, Germany Department of Statistics, University of Hamburg, Germany Introduction: In principle, various factors may influence the accuracy of transpulmonary thermodilution. We analyzed whether veno-venous renal replacement therapy (RRT) has impact on the measurement of cardiac index (CI), intrathoracic blood volume index (ITBVI) and extravascular lung water index (EVLWI). Methods: With ethics approval, we studied 24 critically ill patients (9 female, 15 male) undergoing monitoring by the transpulmonary thermodilution technique for clinical indication and veno-venous RRT. All patients had a 5F-femoral arterial catheter and monitoring system (PV2015L20, Pulsion Medical Systems). 12 patients had a femoral venous 12F-dialysis catheter in situ (Trilyse Expert, Vygon) and 12 patients one placed in the V. cava superior. All patients received heparin for anticoagulation of the extracorporeal circuit. Measurements of CI, ITBVI and EVLWI were performed in triplicate by injecting 15 ml of saline (4–6°C) through the distal port of a triple lumen central venous catheter (Certofix Trio, Braun, Melsungen) into the V. cava superior during RRT, during shortly interrupted therapy (disconnection) and immediately after reconnection. Results: Global hemodynamics were comparable at the three time points (mean standard deviation).

Optimizing cardiac output by fluid loading: effects on liver function and splanchnic microcirculation: A-192

Department of Anesthesiology and Intensive Care Medicine, Friedrich-Schiller-University, Jena, Germany Introduction: Hypovolemia may be associated with hepato-splanchnic hypoperfusion which is of major prognostic relevance (1). In general, optimizing cardiac preload to increase cardiac output is a primary clinical goal. We tested whether increasing cardiac output by optimizing intravascular fluid status leads to an improved regional, i.e. hepato-splanchnic, blood flow and function. Methods: After approval by our Ethics Committee we post-operatively studied 12 patients (mean age 66 13 years) with elective coronary artery bypass grafting who underwent extended hemodynamic monitoring by a pulmonary artery for clinical indication. Microcirculation within the splanchnic area was assessed by gastric tonometry, liver blood flow and function non-invasively by transcutaneous measurement of ICG-PDR. All patients were considered hypovolemic and received hemodynamic optimization by infusion of hydroxyethylstarch (130 kD). Global and regional parameters were measured at baseline and one hour after optimization. All patients were on pressure-controlled mechanical ventilation and respirator settings remained unchanged throughout the study. Data are mean SD. A p 0.05 was considered significant. Results: Overall, 630 130 ml of hydroxyethylstarch were administered. Cardiac index and stroke volume index increased significantly after fluid administration, in average from 2.8 0.7 to 3.6 0.6 l/min/m2 and from 30 7 to 38 8 ml/m2, respectively. Central venous and left atrial pressure significantly increased from 6 2 to 12 2 and from 5 3 to 11 3 mmHg, respectively. However, ICG-PDR and PCO2-gap (difference between gastric mucosal and end-tidal CO2-tension) did not change significantly, i.e. from 21.2 6.5 to 21.6 6.5%/min and from 0.9 0.5 to 1.0 0.7 kPa. Conclusion: Optimizing cardiac output by fluid loading per se is not associated with a significant change in ICG-PDR or gastric mucosal PCO2. However, since ICG-PDR increased in all patients with a value 18%min, particularly patients with a low ICG-PDR may benefit. Further studies are required to test this hypothesis. Reference: 1 Sakka SG et al. Prognostic value of the indocyanine green plasma disappearance rate in critically ill patients. Chest 2002; 122: 1715–20.