Meaning of arterio-venous PCO2 difference in circulatory shock

The arterovenous difference in carbon dioxide tension (DeltaPCO2) can be calculated after simultaneous sampling of arterial blood (PaCO2) and of mixed venous blood from the distal of a pulmonary artery catheter (PvCO2). Under physiological conditions, DeltaPCO2 ranges from 2 to 5 mmHg. The DeltaPCO2 depends on carbon dioxide and cardiac output by a complex fashion. In this article, we detail the influence of these factors on DeltaPCO2 in normoxic conditions and in hypoxic conditions. We bring evidence that DeltaPCO2 cannot serve as a marker of tissue hypoxia contrary to what was initially thought. However, DeltaPCO2 can be considered as a marker of the adequacy of venous blood flow (i.e. cardiac output) to remove the total CO2 produced by the peripheral tissues. In this regard, the knowledge of DeltaPCO2 should help the clinicians for the decision of giving therapy aimed at increasing cardiac output.

[B-natriuretic peptide and cardiological emergencies in childhood]

The increase in B-natiuretic peptide (BNP) is well correlated with cardiovascular symptoms in adults. Its use in children is recent and only partially evaluated. The authors undertook a prospective study of BNP concentrations and its kinetics in 54 children with an average age of 15 months (5 days to 11 years) admitted as paediatric emergencies. The symptoms were dyspnoea (60%), shock (15%), suspicion of Kawasaki disease (15%) and other (10%). Twenty children had BNP levels of more than 100 pg/ml related to decompensation of known congenital heart disease in 7 patients (average BNP 462 +/- 323 pg/ml), due to neonatal coarctation in 2 patients (BNP > 3000 pg/ml), due to cardiomyopathy in 6 patients (BNP= 2576 +/- 1215 pg/ml), due to an arrhythmia in 1 patient (BNP= 3754 pg/ml) and to Kawasaki disease in 4 patients (BNP= 521 +/- 448 pg/ml). Thirty-four children had BNP values of less than 100 pg/ml; 29 had no cardiac disease and 5 had known congenital heart disease with other symptoms. Measuring BNP is quick and economical and is a valuable aid in the diagnosis of cardiac dysfunction in symptomatic children in the emergency room. High BNP values seem to be correlated with the severity of the cardiac disease. Low BNP values seem to have a good negative predictive value in children without underlying cardiac disease. The interpretation of intermediary values, especially when there is previous cardiac disease, is more difficult in view of the absence of known threshold values for different haemodynamic situations. Further studies are required to determine the value of this test for the follow-up and setting up of prognostic values in children with congenital heart disease.

B-type natriuretic peptide (BNP) and N-terminal-proBNP for heart failure diagnosis in shock or acute respiratory distress

BACKGROUND

Plasma B-type natriuretic peptide (BNP) assay is recommended as a diagnostic tool in emergency-room patients with acute dyspnea. In the intensive care unit (ICU), the utility of this peptide remains a matter of debate. The objectives of this study were to determine whether cut-off values for BNP and N-terminal-proBNP (NT-proBNP) reliably diagnosed right and/or left ventricular failure in patients with shock or acute respiratory distress, and whether non-cardiac factors led to an increase in these markers.

METHODS

Plasma BNP and NT-proBNP levels and echocardiographic parameters of cardiac dysfunction were determined in 41 patients within 24 h of the onset of shock or acute respiratory distress.

RESULTS

BNP and NT-proBNP levels were higher in the 25 patients with heart failure than in the other 16 patients: 491.7 +/- 418 pg/ml vs. 144.3 +/- 128 pg/ml and 2874.4 +/- 2929 pg/ml vs. 762.7 +/- 1128 pg/ml, respectively (P < 0.05). In the diagnosis of cardiac dysfunction, BNP > 221 pg/ml and NT-proBNP > 443 pg/ml had 68% and 84% sensitivity, respectively, and 88% and 75% specificity, respectively, but there was a substantial overlap of BNP and NT-proBNP values between patients with and without heart failure. BNP and NT-proBNP were elevated, but not significantly, in patients with isolated right ventricular dysfunction. Patients with renal dysfunction and normal heart function had significantly higher levels of BNP (258.6 +/- 144 pg/ml vs. 92.4 +/- 84 pg/ml) and NT-proBNP (2049 +/- 1320 pg/ml vs. 118 +/- 104 pg/ml) than patients without renal dysfunction.

CONCLUSION

Both BNP and NT-proBNP can help in the diagnosis of cardiac dysfunction in ICU patients, but cannot replace echocardiography. An elevated BNP or NT-proBNP level merely indicates the presence of a 'cardiorenal distress' and should prompt further investigation.

Serum vasopressin concentrations in critically ill patients*

OBJECTIVE

To measure arginine vasopressin (AVP) serum concentrations in critically ill patients.

DESIGN

Prospective study.

SETTING

Twelve-bed general and surgical intensive care unit in a tertiary, university teaching hospital.

PATIENTS

Two-hundred-thirty-nine mixed critically ill patients and 70 healthy volunteers.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Demographic data, hemodynamic variables, vasopressor drug requirements, blood gases, AVP serum concentrations within 24 hrs after admission, multiple organ dysfunction score, and outcome were recorded. Twenty-four hours after admission, study patients had significantly higher AVP concentrations (11.9 +/- 20.6 pg/mL) than healthy controls (0.92 +/- 0.38 pg/mL; p < .001). Males had lower AVP concentrations than females (9.7 +/- 19.5 vs. 15.1 +/- 20.6 pg/mL; p = .014). Patients with hemodynamic dysfunction had higher AVP concentrations than patients without hemodynamic dysfunction (14.1 +/- 27.1 vs. 8.7 +/- 10.8 pg/mL; p = .042). Patients after cardiac surgery (n = 96) had significantly higher AVP concentrations when compared to patients admitted for other diagnoses (n = 143; p < .001). AVP concentrations were inversely correlated with length of stay in the intensive care unit (correlation coefficient, -0.222; p = .002). There was no correlation between serum AVP concentrations and the incidence of shock or specific hemodynamic parameters. Four (1.7%) of the 239 study patients met criteria for an absolute AVP deficiency (AVP, <0.83 pg/mL), and 32 (13.4%) met criteria for a relative AVP deficiency (AVP, <10 pg/mL, and mean arterial pressure, <70 mm Hg). In shock patients, relative AVP deficiency occurred in 22.2% (septic shock), 15.4% (postcardiotomy shock), and 10% (shock due to a severe systemic inflammatory response syndrome) (p = .316).

CONCLUSIONS

AVP serum concentrations 24 hrs after intensive care unit admission were significantly increased in this mixed critically ill patient population. The lack of a correlation between AVP serum concentrations and hemodynamic parameters suggests complex dysfunction of the vasopressinergic system in critical illness. Relative and absolute AVP deficiency may be infrequent entities during acute surgical critical illness, mostly remaining without significant effects on cardiovascular function.

PLATONIN, A CYANINE PHOTOSENSITIZING DYE, CAUSES ATTENUATION OF CIRCULATORY SHOCK, HYPERCOAGULABLE STATE, AND TISSUE ISCHEMIA DURING HEAT STROKE

The aim of this study was to investigate the therapeutic effect of platonin, a cyanine photosensitizing dye as well as an inhibitor of proinflammatory cytokines, in an animal model of heat stroke. Anesthetized rats, immediately after the onset of heat stroke, were divided into two major groups and given the following: normal saline (1 mL per kg body weight) intravenously, or platonin (12.5-50 microg/mL per kg body weight) intravenously. They were exposed to ambient temperature of 43 degrees C to induce heat stroke. Another group of rats was exposed to room temperature (26 degrees C) and used as normothermic controls. Their physiologic and biochemical parameters were continuously monitored. When the vehicle-treated rats underwent heat exposure, their survival time values were found to be 18 to 22 min. Resuscitation with intravenous doses of platonin, but not normal saline, immediately at the onset of heat stroke, significantly improved survival during heat stroke (41-147 min). All heat-stressed animals displayed systemic inflammation and activated coagulation, evidenced by increased tumor necrosis factor-alpha, prothrombin time, activated partial thromboplastin time, fibrinogen degradation products, and D-dimer, and decreased platelet count and protein C. Biochemical markers evidenced cellular ischemia and injury/dysfunction: plasma levels of blood urea nitrogen, creatinine, glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, and alkaline phosphatase, and striatal levels of partial pressure of oxygen, local cerebral blood flow, glycerol, glutamate, and lactate/pyruvate were all elevated during heat stroke. The systemic inflammation, hypercoagulable state, and cerebral ischemia and injury during heat stroke were all significantly suppressed by platonin. The data demonstrate that platonin therapy may resuscitate heat stroke victims by reducing circulatory shock, systemic inflammation, hypercoagulable state, and tissue ischemia and injury.

Normovolaemia defined by central blood volume and venous oxygen saturation

1. The intravenous administration of fluid and blood has to balance the danger of unexpected death in response to a reduction of central blood volume (CBV) against that of developing pulmonary and/or peripheral oedema. 2. The initial cardiovascular response to haemorrhage is similar to that developed in response to standing. In the upright position, adults are subjected to a reduction of CBV of approximately 0.5 L and can therefore tolerate a blood loss of approximately 1 L when supine. 3. However, volume administration directed by cardiovascular variables is seldom precise, even with integration of the bradycardia and hypotension developed when CBV decreases by approximately 30%. Immediate intervention is needed because such a reduction in CBV raises the lower limit of cerebral autoregulation to approximately 80 mmHg compared with the commonly considered value of approximately 60 mmHg with an associated risk of developing brain ischaemia and irreversible shock. 4. Alternatively, the volume load can be monitored both directly and accurately by means of thoracic electrical admittance. A functional definition of normovolaemia may be the filling of the heart that ensures cardiac output and oxygen delivery. From that perspective, supine humans are normovolaemic in that a maximal venous oxygen saturation (Svo2) is established. 5. Conversely, Svo2 decreases in the upright position and, with a blood loss of approximately 100 mL, Svo2 is reduced by 1%. It is suggested that, in supine humans and guided by Svo2, normovolaemia may be established to an accuracy of approximately 100 mL and that its adequacy is controlled by recording cerebral oxygenation.

[Influence of the enteral feeding of levorotatory arginine on severely burned patients during shock stage]

OBJECTIVE

To investigate the effects and the mechanism of action of postburn dietary supplementation of levorotatory arginine (L-Arg) on burn shock resuscitation in severely burned patients.

METHODS

This study was designed to be a prospective, randomized, single blinded and controlled one. Twenty burn patients with total burn surface area (TBSA) more than 30% were enrolled and randomized into two groups; 1) Group A (n = 10): enteral feeding of 50 g/L glucose normal saline (GNS) 500 ml per day containing L-Arg (400 mg/kg.day) at equal pace with fluid infusion for shock resuscitation for 4 days. 2) Group C (n = 10): enteral feeding with only 50 g/L GNS 500 ml per day for 4 days. All of the twenty patients received equal amount of enteral feeding via an intra-gastric tube with the aid of an enteral feeding pump, started within 24 postburn hours (PBH). Venous blood was harvested from all the patients in both groups on 1, 2, 3 and 4 postburn day (PBD) for the determination of serum content of nitric oxide (NO), malondialdehyde (MDA) and the activity of serum superoxide dismutase (SOD). And the arterial content of lactate (BL) was also determined concomitantly.

RESULTS

The results indicated that the serum SOD activity in group A was increased after burns, peaked on 4 PBD (68 +/- 23 U/ml), and it was obviously higher than that in group C (31 +/- 9 U/ml, P < 0.01). The serum contents of MDA and NO were decreased in both groups after burns. On 2 PBD, the serum NO level in group A decreased to the lowest level (50 +/- 14 micromol/L), which was obviously lower compared with group C (78 +/- 22 micromol/L, P < 0.01). On 4 PBD, serum MDA levels in group A (3.4 +/- 0.8 micromol/L) and group C (3.5 +/- 1.3 micromol/L) were decreased to the lowest level. The BL content in group A was obviously lower than that in group C on 2 and 3 PBD (P < 0.05 or 0.01).

CONCLUSION

Enteral supplementation of L-arginine can decrease excessive NO production to a relatively normal level, and it might be beneficial to resuscitation of burn shock. It might also exert a protective effect against ischemia/reperfusion injury to burn patients.

Thrombocytopenia due to hypotension unrelated to infection: shock marrow

Although peripheral blood cytopenias are observed in clinical practice following hypotensive episodes unrelated to infection, there has previously been no formal description of this in the medical literature. We retrospectively reviewed all medical intensive care unit records from two hospitals over a 5-year period to identify cases in which sustained hypotension had occurred that was unrelated to infection. After initial review, 10 records were identified that met our criteria (systolic blood pressure < 90 mmHg for at least 6 h, with no evidence of sepsis or use of drugs commonly associated with suppression of haematopoiesis). All 10 of these patients were found to develop thrombocytopenia. The degree of thrombocytopenia correlated with the severity and duration of hypotension. Severe thrombocytopenia appeared to be associated with a poor outcome. Thrombocytopenia following shock unrelated to sepsis is common and is presumably related to hypoxic injury to haematopoietic progenitor cells.

THE ACUTE INFLAMMATORY RESPONSE IN DIVERSE SHOCK STATES

A poorly controlled acute inflammatory response can lead to organ dysfunction and death. Severe systemic inflammation can be induced and perpetuated by diverse insults such as the administration of toxic bacterial products (e.g., endotoxin), traumatic injury, and hemorrhage. Here, we probe whether these varied shock states can be explained by a universal inflammatory system that is initiated through different means and, once initiated, follows a course specified by the cellular and molecular mechanisms of the immune and endocrine systems. To examine this question, we developed a mathematical model incorporating major elements of the acute inflammatory response in C57Bl/6 mice, using input from experimental data. We found that a single model with different initiators including the autonomic system could describe the response to various insults. This model was able to predict a dose range of endotoxin at which mice would die despite having been calibrated only in nonlethal inflammatory paradigms. These results show that the complex biology of inflammation can be modeled and supports the hypothesis that shock states induced by a range of physiologic challenges could arise from a universal response that is differently initiated and modulated.

[When safety becomes a danger. Penetrating trauma by side impact protection]

We report the case of a penetrating injury of the abdomen by an iron bar of a side impact protection after a traffic accident. The iron bar of the side impact protection entered the lateral thigh, penetrated the pelvis and retroperitoneum and left the body lateral of the spine at the L4 level. The patient was fixed by the iron bar to the car seat. The mechanism of the accident, the patient's symptoms and the initial treatment of the patient are described and discussed.

Arginine vasopressin and serum nitrite/nitrate concentrations in advanced vasodilatory shock

BACKGROUND

Arginine-vasopressin (AVP) can successfully stabilize hemodynamics in patients with advanced vasodilatory shock. It has been suggested that inhibition of cytokine-induced nitric oxide production may be an important mechanism underlying AVP-induced vasoconstriction. Therefore, serum concentrations of nitrite/nitrate (NOx), the stable metabolite of nitric oxide, were measured in patients suffering from advanced vasodilatory shock treated with either AVP in combination with norepinephrine (NE) or NE alone.

METHODS

This trial was a separate study arm of a previously published prospective, randomized, controlled study on the effects of AVP in advanced vasodilatory shock. Thirty-eight patients were prospectively randomized to receive a combined infusion of AVP (4 U h(-1)) and NE, or NE infusion alone. Serum NOx concentrations were measured at baseline, 24, and 48 h after randomization. The increase in mean arterial pressure during the first hour after study enrollment was documented in all patients.

RESULTS

No difference in NOx concentrations was found between groups throughout the study period. AVP patients demonstrated a significantly greater increase in mean arterial pressure than NE patients (22 +/- 10 vs. 5 +/- 9 mmHg; P < 0.001). The magnitude of pressure response to AVP was not correlated with NOx concentrations before start of AVP infusion (Pearson's correlation coefficient, -.009; P = 0.971).

CONCLUSION

Cardiovascular effects of AVP infusion in advanced vasodilatory shock are not mediated by a clinically relevant reduction in serum NOx concentrations. Therefore, hemodynamic improvement of patients in advanced vasodilatory shock during continuous infusion of AVP has to be attributed to other mechanisms than inhibition of nitric oxide synthase. In addition, the magnitude of pressure response to AVP is not correlated with baseline concentrations of NOx.

Utility of B-type natriuretic peptide for the evaluation of intensive care unit shock*

OBJECTIVES

Among patients with congestive heart failure, B-type natriuretic peptide measurement is useful to estimate filling pressures and to prognosticate adverse outcome. However, among critically ill intensive care unit patients with shock, the utility of B-type natriuretic peptide to assess cardiac hemodynamics or prognosis has not been explored.

DESIGN

Clinical investigation.

SETTING

Hospital.

PATIENTS

Forty-nine patients with shock and indication for pulmonary artery catheterization.

INTERVENTIONS

Analysis for B-type natriuretic peptide was performed on blood obtained at the time of catheter placement.

MEASUREMENTS AND MAIN RESULTS

Correlations between B-type natriuretic peptide and pulmonary artery occlusion pressure as well as cardiac index were calculated using Spearman analysis. Mortality at the time of study completion was correlated with B-type natriuretic peptide values and Acute Physiology and Chronic Health Evaluation II scores, and logistic regression identified independent predictors of mortality. A wide range of B-type natriuretic peptide concentrations was seen in intensive care unit patients (<5 to >5000 pg/mL); only eight patients (16%) had normal B-type natriuretic peptide concentrations. Log-transformed B-type natriuretic peptide concentrations did not correlate with interpatient cardiac index or pulmonary artery occlusion pressure (all p = not significant); however, a B-type natriuretic peptide <350 pg/mL had a negative predictive value of 95% for the diagnosis of cardiogenic shock. Median B-type natriuretic peptide concentrations were higher in those who died than those who survived (943 pg/mL vs. 378 pg/mL, p <.001). In multivariable analysis, a B-type natriuretic peptide concentration in the highest log-quartile was the strongest predictor of mortality (odds ratio = 4.50, 95% confidence interval = 1.87-99.0, p <.001).

CONCLUSION

B-type natriuretic peptide concentrations are frequently elevated among critically ill patients in the intensive care unit and cannot be used as a surrogate for pulmonary artery catheterization. B-type natriuretic peptide concentrations in intensive care unit shock may provide powerful information for use in mortality prediction.

Effect of Ibuprofen on Interleukin-1??-Induced Abnormalities in Hemodynamics and Oxygen Metabolism in Rabbits

We showed previously that the administration of interleukin (IL)-1beta induces circulatory shock and impairs the oxygen consumption (VO2)/oxygen delivery (DO2) relation by increasing the slope of the supply-independent line in rabbits. We tested the effect of ibuprofen, a specific inhibitor of the development of shock in this model, on the VO2/DO2 abnormality. Eighteen rabbits were divided randomly into three groups (n = 6 each) and intravenously given 10 microg/kg of IL-1beta alone or 10 microg/kg of IL-1beta followed by 10 mg/kg of ibuprofen or saline (control). All rabbits were subjected to stepwise cardiac tamponade by inflation of a handmade balloon placed into the pericardial sac to reduce DO2. The VO2/DO2 relation was then analyzed by the dual line method. The IL-1beta group had a significantly lower mean arterial pressure than that of the other groups before cardiac tamponade, and this reduction in mean arterial pressure was suppressed completely by treatment with ibuprofen. The cardiac index did not differ between groups. The slope of the supply-independent line was increased significantly by administration of IL-1beta, and this increase was attenuated significantly by treatment with ibuprofen (IL-1beta only: y = 0.14x + 6.1, ibuprofen: y = 0.06x + 8.5, control: y = 0.01x + 9.0). We conclude that ibuprofen reversed the IL-1beta-induced shock by restoring the systemic vascular resistance to normal and thereby normalized the VO2/DO2 relation in the supply-independent range of DO2.

Hemoglobin solutions

OBJECTIVE

To review current knowledge about cell-free hemoglobin solutions.

DATA SOURCE

A computerized MEDLINE search was used to retrieve all studies concerning cell-free hemoglobin solutions from 1990 to 2003. The reference lists of all available review articles and primary studies were also reviewed to identify references not identified in the computerized search.

STUDY SELECTION

All clinical and experimental studies involving cell-free hemoglobin solutions were included.

DATA EXTRACTION

From the selected studies, information was obtained regarding the experimental model or the study population in which cell-free hemoglobin solutions were investigated, the type of cell-free hemoglobin solution used, their deleterious or beneficial effects, and their possible indications.

DATA SYNTHESIS

In many studies, hemoglobin solutions were considered as efficient resuscitative agents and good alternatives to red blood cell transfusion, owing to their marked vasopressor effect, coupled with their capacity to improve the microcirculation and rapidly restore metabolic parameters. The main problems identified include excessive systemic vasoconstriction and oxidative damage. Initial enthusiasm in the development of hemoglobin solutions has been tempered recently by the negative results of a U.S. multicenter trial studying the early infusion of diaspirin cross-linked hemoglobin in trauma patients. Nevertheless, the properties of diaspirin cross-linked hemoglobin (and particularly the strong vasopressor effects) cannot be attributed to all hemoglobin solutions, and results of new clinical studies are eagerly awaited to evaluate the potential benefit of such solutions in the management of trauma patients.

CONCLUSIONS

Today, we are aware of the effects of the first generation of blood substitutes. Further research is ongoing into newer solutions. One area of interest is the development of new molecular structures to decrease nitric oxide binding, thus minimizing any adverse events and maximizing potential benefits. Nevertheless, possible adverse effects need to be carefully evaluated before these agents can be widely administered.

Assessment of adipose tissue metabolism by means of subcutaneous microdialysis in patients with sepsis or circulatory failure

To evaluate the role of adipose tissue in the metabolic stress response of critically ill patients, the release of glycerol and lactate by subcutaneous adipose tissue was assessed by means of microdialysis in patients with sepsis or circulatory failure and in healthy subjects. Patients with sepsis had lower plasma free fatty acid concentrations and non-significant elevations of plasma glycerol concentrations, but higher adipose-systemic glycerol concentrations gradients than healthy subjects or patients with circulatory failure, indicating a stimulation of subcutaneous adipose lipolysis. They also had a higher lipid oxidation. Lipid metabolism (adipose-systemic glycerol gradients, lipid oxidation) was not altered in patients with circulatory failure. These observations highlight major differences in lipolysis and lipid utilization between patients with sepsis and circulatory failure. Hyperlactataemia was present in both groups of patients, but the adipose-systemic lactate concentration gradient was not increased, indicating that lactate production by adipose tissue was not involved. This speaks against a role of adipose tissue in the development of hyperlactataemia in critically ill patients.

Plasma leptin levels in patients with burn injury: a preliminary report

The purpose of this study was to investigate the relationship between the plasma leptin level and clinical parameters in patients with burn injury. Six patients with burn injury were admitted to the Emergency and Critical Care Medicine Center of St. Marianna University Hospital within 1h after injury. Plasma levels were monitored for leptin, proinflammatory cytokines (interleukin (IL)-1 beta, IL-6, tumor necrosis factor alpha (TNF alpha)), stress-related parameters (adrenocorticotropic hormone (ACTH), cortisol, and C-reactive protein (CRP)). The change in individual plasma leptin levels did not show similar pattern in all these patients. However, leptin levels remained within the normal range, except in a patient (Case 1) complicated with severe hypovolemic shock. Plasma ACTH and cortisol levels were also elevated in most of the patients. Examination of relationships among plasma leptin, proinflammatory cytokines, and stress-related parameters revealed a significant positive correlation between the plasma leptin level and IL-1 beta or IL-6. These results suggest that the plasma leptin level may have some relations to plasma proinflammatory cytokines in pathophysiologic responses to critical conditions of burn injury.

[Fibronectin--an important factor of nonspecific body defense]

The paper shows chief properties of fibronectin and its significance in formation of unspecific bodily defence. Data are submitted on the role fibronectin plays both in the organism of a child and in that of an adult person in different morbid conditions.

Resuscitation with Ringer's ethyl pyruvate solution prolongs survival and modulates plasma cytokine and nitrite/nitrate concentrations in a rat model of lipopolysaccharide-induced shock

The glycolytic intermediate, pyruvate, is capable of scavenging reactive oxygen species (ROS). However, this compound is relatively unstable and hence is not useful as a therapeutic agent. Ethyl pyruvate, a simple derivative of pyruvate, appears to be more stable, and when formulated in a calcium-containing Ringer's-type balanced salt solution (REPS), has been shown to be salutary in rat models of two pathophysiological conditions--mesenteric ischemia/reperfusion and hemorrhagic shock/resuscitation--that are thought to be mediated, at least in part, by ROS. Because ROS also have been implicated in the pathogenesis of lipopolysaccharide (LPS)-induced shock, we carried out a series of experiments to determine if REPS is beneficial in this condition. Anesthetized rats were challenged with intravenous LPS (20 mg/kg). When mean arterial pressure (MAP) decreased to 60 mmHg, 3- to 5-mL boluses of either REPS (n = 10) or Ringer's lactate solution (RLS; n = 10) were infused as needed to prevent MAP from decreasing further. By design, the maximal volume of fluid infused was 7 mL/kg. Resuscitation with REPS as compared with RLS prolonged survival time (498 +/- 48 min vs. 362 +/- 30 min; P = 0.0014). Resuscitation with REPS as compared with RLS also was associated with significantly lower circulating concentrations of nitrite/nitrate and interleukin (IL)-6 and higher plasma levels of IL-10. These data support the view that delayed treatment with REPS modulates the inflammatory response to LPS, and prolongs survival time in a lethal model of endotoxic shock.

Dopamine does not correct oxygen consumption/oxygen delivery relation abnormality during vasomotor shock induced by interleukin-1beta

We previously showed that interleukin 1beta (IL-1beta) induces vasomotor shock and impairs the oxygen consumption (VO2)/oxygen delivery (DO2) relation by increasing the slope of the supply-independent line in rabbits. In the present study, we investigated the inotropic effect of dopamine on the VO2/DO2 abnormality induced by IL-1beta. Twelve rabbits were divided into two groups (n = 6, each) and were given 10 microg/kg of IL-1beta or saline (control) intravenously. After baseline measurements were obtained, dopamine was infused continuously at a rate of 20 microg/kg/min throughout the study in both groups. All rabbits were subjected to stepwise cardiac tamponade to reduce the DO2 to <5 mL/min/kg by inflation of a handmade balloon placed into the pericardial sac. The VO2/DO2 relation was then analyzed by the dual-line method. Dopamine failed to correct the IL-1beta-induced decrease in mean arterial pressure to the baseline level. Dopamine significantly increased cardiac index in both groups, resulting in significant increases in DO2 (IL-1beta, 28.5 +/- 6.0 mL/min/kg from baseline 24.1 +/- 3.5 mL/min/kg; control, 27.7 +/- 2.9 mL/min/kg from baseline 22.9 +/- 2.9 mL/min/kg), but did not affect VO2 (IL-1beta, 10.0 +/- 0.5 mL/min/kg from baseline 9.9 +/- 0.7 mL/min/kg; control, 10.2 +/- 0.4 mL/min/kg from baseline 10.2 +/- 0.2 mL/min/kg). The IL-1beta group showed a significantly greater supply-independent line slope than that of controls (IL-1beta, y = 0.14x + 6.3; control, y = 0.06x + 8.6) during stepwise decreases in DO2. These results indicate that continuous infusion of dopamine at 20 microg/kg/min increases DO2 but does not correct the vasomotor disturbance or VO2/DO2 abnormality caused by IL-1beta.

Enterococcus faecalis exacerbates burn injury-induced host responses in rats

Pathophysiology of burn injury with complications of gram-positive infections is not well characterized. We have developed an in vivo rat model to study the effects of burn injury along with intra-abdominal inoculation of Enterococcus faecalis. We hypothesized that although burn injury or E. faecalis inoculation by itself may not induce significant pathophysiological responses, the combination of the two can lead to adverse pathophysiological consequences. Sprague-Dawley rats were divided into 4 groups: group 1(C), controls; group 2(B), burn injury on 30% total body surface area; group 3(EF), intra-abdominal implantation of bacterial pellet impregnated with E. faecalis; group 4(B+EF), burn injury plus bacterial pellet implantation. The mortality was 25% and 60% on day 1 and 2 in Group 4(B+EF), respectively; no significant mortality was observed in other groups. In group 4(B+EF), metabolic acidosis, respiratory alkalosis, and a hyperdynamic state developed on day 1, and metabolic and respiratory acidosis and a hypodynamic state on day 2. There were no significant alterations in metabolic or hemodynamic measurements in other groups. Intestinal microvascular permeability to albumin on day 1 and 2 was increased in group 4(B+EF). In group 2(B), microvascular permeability was not increased significantly. Although the permeability was increased on day 1 in group 3(EF), it declined on day 2. The metabolic and hemodynamic alterations were correlated with increased intestinal microvascular permeability to albumin. E. faecalis appeared to be involved in initiating a vicious cycle of burn injury-mediated disruption of intestinal integrity along with metabolic and hemodynamic derangements.