J. L. Vincent

Toe temperature versus transcutaneous oxygen tension monitoring during acute circulatory failure

Measurements of toe temperature and transcutaneous PO2 (PtcO2) have been both suggested for non-invasive assessment of peripheral blood flow in acute circulatory failure. The underlying principle of the two methods is that cutaneous vasoconstriction occurs early when tissue perfusion is altered. In 15 patients, we compared the two measurements during cardiogenic shock (27 measurements) or septic shock (29 measurements). Toe-ambiant temperature gradient and PtcO2 correlated well together (r=0.66, p(0.001) especially in hyperkinetic septic shock (r=0.79, p(0.001). In cardiogenic shock, toe-ambiant temperature correlated well with cardiac index (r=0.63), stroke index (r=0.64) and oxygen transport (r=0.65), and these correlations were stronger than for PtcO2. In septic shock, both techniques were poor indicators of blood flow indexes but PtcO2 rather correlated with arterial pressure (r=0.66) and left ventricular work (r=0.66). Trend evaluation of data revealed in cardiogenic shock that the increase in toe temperature usually preceded the increase in PtcO2. Since measurement of PtcO2 is technically more complicated, correlates less well with standard hemodynamic parameters and later reflects cardiovascular improvement, it has no advantage over measurement of toe temperature in circulatory shock. In cardiogenic shock, measurements of toe temperature can reliably track cardiac output changes. In septic states, however, non-invasive assessment of skin perfusion is of limited interest.

Physiology of VO2/DO2

Cellular energy is supplied in the form of high energy phosphate compounds, such as ATP, by metabolic reactions involving the oxidation of hydrocarbons. The concentration of ATP in most cells is maintained by the mitochondrial electron transport systems. Under normal conditions the amount of oxygen present in the mitochondria greatly exceeds that required to maintain oxidative phosphorylation. However when oxygen delivery falls, less efficient anaerobic metabolism takes over, leading to lactate production and acidosis. Cellular processes fail as energy supplies fall, and organ system function deteriorates. Oxygen is thus essential for the normal activity and survival of tissues.

Hemodynamics. PCO2 gradient

Mortality rate of elective infrarenal aortic aneurysm (AA) surgery has been reduced during the last 2 decades but not that of ruptured AA (RAA) operated on emergency (mortality rate about 45 %). However, autotransfusion has been introduced recently in the management of ruptured AA and appeared to reduce drastically mortality of RAA in a retrospective analysis of patients operated during the last 6 years. Forty-three patients were operated on for RAA from January 1986 to December 1991. Anaesthesia, surgical technics, or management of fluid replacement were identical for all patients except autotransfusion (AT) (Stat device, Dideco Lab.) which was used in some patients (n= 17) whenever it was possible. Number of death during surgery and at one month following surgery defined perioperative and postoperative mortality, respectively. Morbidity included postoperative renal or cardiac failures, or sepsis complications (pulmonary or septicemic infections). Stepwise regression analysis was used to delineate predicting factors of mortality and morbidity. Perioperative and postoperative mortality rates were 16.3% and 32.4%, respectively. Preoperative low blood pressure (systolic blood pressure less than 60 mmHg) was the best predicting factor of perioperative mortality (p=0.016) but AT use was the only predicting factor of postoperative mortality (p=0.002). Postoperative mortality of autotransfused patients was thus significantly lower than that of the other patients (12% vs 46%, respectively, p=0.018). Postoperative complications occured in 37 (82.9%) patients: 37 had renal insufficiency (creatinine clearance < 50 mVmin at day 1 after surgery) but only 2 patients required dialysis. Sepsis complications occured frequently (38.2%) mainly as pulmonary infection (35.3%), but no predictive factor of morbidity can be identified from stepwise regression analysis. In conclusion, perioperative autotransfusion may reduce mortality of RAA surgery and should be recommended.

Hemodynamic and metabolic alterations associated with septic acute kidney injury in experimental sepsis.

The role of renal perfusion in the development of septic acute kidney injury (AKI) remains elusive. When septic AKI develops in the presence of hypotension, renal dysfunction is considered to be caused by reduced renal blood flow and tissue hypoxia. However, an integrated view of the effects of sepsis on renal blood flow, oxygenation and local metabolism is currently lacking.

Sepsis: Pulsdruckvariationbei lungenprotektiver Beatmung

Um die Reaktion auf Flussigkeitsgabe vorherzusagen gab es bereits mehrere Studien, welche die Pulsdruckvariation (PPV) untersuchten. Jedoch wurden hierbei fast nie lungenprotektive Beatmungsstrategien benutzt. Daher untersuchten F. G. R. Freitas und Kollegen aus Sao Paulo, Brasilien, eben diese Fragestellung prospektiv.

Les autres techniques de mesure du débit cardiaque (en dehors des ultrasons)

La mesure du debit cardiaque peut etre obtenue par diverses techniques, incluant les techniques de dilution, l’analyse de l’onde de pouls, les ultrasons, et l’analyse des gaz expires et la bio-impedance. Dans ce chapitre, nous nous focaliserons sur l’analyse de la courbe de pression arterielle, avec ou sans calibration, et sur l’analyse des gaz expires; le principe de la thermodilution et des ultrasons seront developpes dans d’autres chapitres.

Le débit cardiaque est-il adapté?

La mesure du debit cardiaque est l’un des elements essentiels de l’evaluation hemodynamique. En effet, le debit cardiaque est le determinant principal du transport en oxygene aux tissus (DO2). L’anemie et l’hypoxemie peuvent etre compensees par une augmentation du debit cardiaque, tandis qu’une diminution du debit cardiaque ne peut qu’entrainer une diminution de la DO2.

RED BLOOD CELL DESIALYLATION, AS OBSERVED IN SEPSIS ALTERS THEIR SHAPE AND BIOCHEMISTRY

TOWARDS RESOLVING THE CHALLENGE OF SEPSIS DIAGNOSTIC. Thomas Herget* and Thomas Joos . *Merck KGaA, Darmstadt, Germany; NMI Natural and Medical Sciences Institute at the University of Tübingen, Reutlingen, Germany Biomarkers have proven to be very useful in clinical conditions such as heart attack, stroke and cancer. There are characteristics linked to sepsis like in blood pressure, body temperature and heart rate. Efforts over the last decade to improve diagnosis for infectious inflammation have been unsuccessful in identifying a single and universal biomarker that provides sufficiently high sensitivity and specificity. In gramnegative septicemia and following major abdominal trauma, the determination of endotoxin continues to be a leading candidate which could become adopted into clinical practice. The importance of endotoxin measurement continues to grow as more clinicians recognize the added value of measuring endotoxin in critically ill patients and with the emergence of major pharmaceutical trials directly targeting endotoxin in the bloodstream. However, hundreds of other candidates potentially serving as biomarker for sepsis have been recently described, e.g. cysteinyl-leukotriene (LTC4) generation, procalcitonin (PCT) and C-reactive protein (CRP). However, none of them fulfils the criteria requested by clinicians, namely being specific and sensitive. The presentation will discuss criteria for a sepsis biomarker, will give an overview of obtaining samples from appropriate cell systems and from patients. Furthermore, tools will be described to identify marker candidates on genetic-, proteinand metabolite level. The integration of these data sets covering e.g. signal transduction, protein : protein interaction, gene expression with the help of bioinformatics and systems biology will help to validate such candidates. The final goal is manufacturing a robust diagnostic device for clinical routine work. A solid sepsis diagnostics method will be beneficial for patients, but also for the healthcare systems and will open challenges for the pharmaceutical industry.

EFFECTS OF HYDROXYETHYL STARCH ADMINISTRATION ON RENAL FUNCTION IN CRITICALLY ILL PATIENTS.: 249-T

BACKGROUND The influence of hydroxyethyl starch (HES) solutions on renal function is controversial. We investigated the effect of HES administration on renal function in critically ill patients enrolled in a large multicentre observational European study. METHODS All adult patients admitted to the 198 participating intensive care units (ICUs) during a 15-day period were enrolled. Prospectively collected data included daily fluid administration, urine output, sequential organ failure assessment (SOFA) score, serum creatinine levels, and the need for renal replacement therapy (RRT) during the ICU stay. RESULTS Of 3147 patients, 1075 (34%) received HES. Patients who received HES were older [mean (SD): 62 (SD 17) vs 60 (18) years, P = 0.022], more likely to be surgical admissions, had a higher incidence of haematological malignancy and heart failure, higher SAPS II [40.0 (17.0) vs 34.7 (16.9), P < 0.001] and SOFA [6.2 (3.7) vs 5.0 (3.9), P < 0.001] scores, and less likely to be receiving RRT (2 vs 4%, P < 0.001) than those who did not receive HES. The renal SOFA score increased significantly over the ICU stay independent of the type of fluid administered. Although more patients who received HES needed RRT than non-HES patients (11 vs 9%, P = 0.006), HES administration was not associated with an increased risk for subsequent RRT in a multivariable analysis [odds ratio (OR): 0.417, 95% confidence interval (CI): 0.05-3.27, P = 0.406]. Sepsis (OR: 2.03, 95% CI: 1.37-3.02, P < 0.001), cardiovascular failure (OR: 6.88, 95% CI: 4.49-10.56, P < 0.001), haematological cancer (OR: 2.83, 95% CI: 1.28-6.25, P = 0.01), and baseline renal SOFA scores > 1 (P < 0.01 for renal SOFA 2, 3, and 4 with renal SOFA = 0 as a reference) were all associated with a higher need for RRT. CONCLUSIONS In this observational study, haematological cancer, the presence of sepsis, cardiovascular failure, and baseline renal function as assessed by the SOFA score were independent risk factors for the subsequent need for RRT in the ICU. The administration of HES had no influence on renal function or the need for RRT in the ICU.

Effects of Adrenergic Agents on the Hepato-Splanchnic Circulation: An Update

Recent studies [1, 2] have implicated the hepato-splanchnic area in the development of multiple organ failure. Important alterations can take place in the gut and the liver during sepsis, A decreased gastric intramucosal pH (pHi), thought to reflect inadequate gut perfusion, is often encountered in sepsis and is associated with increased mortality rates [3, 4]. Liver dysfunction is also common in sepsis and alterations in liver blood flow may contribute to it. The hepatic venous oxygen saturation (ShO2) is often decreased [5-9], reflecting an imbalance between oxygen demand and supply in the hepato-splanchnic area. Also, the liver could be a major source of cytokine release [10], possibly triggered by hypoxia.