Early hemodynamic course of septic shock

Strong correlation between doppler snuffbox resistive index and systemic vascular resistance in septic patients

PURPOSE

To compare systemic vascular resistance index (SVRI) as measured by invasive transpulmonary indicator dilution (TPID) and non-invasive Doppler-derived resistive index in septic patients.

METHODS

We measured the snuffbox resistive index (SBRI) in both hands of septic patients who received hemodynamic monitoring by TPID prospectively.

RESULTS

Thirty-six patients with septic shock were enrolled (median acute physiology and chronic health evaluation II score: 23; median age: 64 years). Four SBRI values were measured in each patient, for a total of 96 patient days and 951 ultrasound measurements. The correlation coefficients between SVRI and the four SBRI values were all higher than 0.87 (p < .001). A higher SVRI was associated with sharp waveforms and reversed diastolic flow. A resistive index (RI) of 0.97 was the lower limit of normal SVRI (1700 dyn*s*cm^-5*m²), and an RI of 1.1 was the upper limit of normal SVRI (2400 dyn*s*cm^-5*m²).

CONCLUSIONS

Using ultrasound to measure RI is a noninvasive, inexpensive, reliable method to evaluate peripheral vascular resistance in septic patients, and it is highly correlated with SVRI. In addition, SBRI can be used to evaluate peripheral circulatory disturbances in septic patients.

Hemodynamic Analysis of Pediatric Septic Shock and Cardiogenic Shock Using Transpulmonary Thermodilution

Septic shock and cardiogenic shock are the two most common types of shock in children admitted to pediatric intensive care units (PICUs). The aim of the study was to investigate which hemodynamic variables were associated with mortality in children with shock. We retrospectively analyzed 50 children with shock (37 septic shock cases and 13 cardiogenic shock cases) in the PICU and monitored their hemodynamics using transpulmonary thermodilution from 2003 to 2016. Clinical factors were analyzed between the patients with septic and cardiogenic shock. In addition, hemodynamic parameters associated with mortality were analyzed. The 28-day mortality was significantly higher in the septic group than in the cardiogenic group (p = 0.016). Initially, the parameters of cardiac output and cardiac contractility were higher in the septic group (p < 0.05) while the parameters of preload and afterload were all higher in the cardiogenic group (p < 0.05). Cardiac index was significantly lower in the nonsurvivors of cardiogenic shock at the time of initial admission and after the first 24 hours (both p < 0.05), while systemic vascular resistance index (SVRI) was significantly lower in the nonsurvivors of septic shock (p < 0.001). Therefore, during the first 24 hours after intensive care, SVRI and cardiac index are the most important hemodynamic parameters associated with mortality.

Effect of N-acetylcysteine and fructose-1,6-bisphosphate in the treatment of experimental sepsis

Sepsis is a syndrome caused by uncontrolled systemic inflammatory response of the individual, which represents a serious epidemiological problem worldwide. The aim of this study was to investigate the effect of N-acetylcysteine (NAC) and fructose-1,6-bisphosphate (FBP) in the treatment of experimental sepsis. We used rats that were divided into five experimental groups: normal control (not induced), septic control (induced using a capsule with non sterile fecal content and Escherichia coli), treated with FBP (500 mg/kg i.p.), treated with NAC (150 mg/kg i.p.), and treated with the combination of FBP with NAC. In the group treated with NAC, 16.68% of the mice survived, the FBP reduced the mortality of mice during the acute stage of the disease and increased the animals' survival time in 33.34%, and the combination of drugs had no effect. Our results show that NAC prevented the mortality of animals after septic induction. These data confirm the validity of the use of NAC in the treatment of sepsis. Our data also show that the synergistic action with FBP does not improve the picture.

The hemodynamics of human septic shock relate to circulating innate immunity factors

The role of innate immunity, e.g., complement activation and cytokine release in the hemodynamic alterations in the course of human septic shock is largely unknown. We prospectively studied 14 consecutive septic shock patients with a pulmonary artery catheter in place. For 3 days after admission, hemodynamic variables and plasma levels of C3a, a product of complement activation, and interleukin (IL)-6 and tumor necrosis factor alpha (TNF-α) were measured 6-hourly. Doses of vasoactive drugs were recorded. Of the 14 patients, 8 died in the ICU. Patients had a hyperdynamic circulation with tachycardia, mild hypotension, increased cardiac index, peripheral vasodilation and myocardial depression. C3a, IL-6 and TNF-α plasma levels were supranormal in 123 of 138 (89%), 132 of 138 (96%) and 83 of 111 (75%) measurements, respectively. Independently of blood culture results, treatment with vasoactive drugs and outcome, mean arterial blood pressure and systemic vascular resistance index were lower when IL-6 levels were higher and left ventricular function was less depressed when C3a levels were higher in the course of septic shock. The TNF-α levels did not invariably relate to peripheral vascular and myocardial function parameters. Our serial observations suggest that, in human septic shock, peripheral vasodilation is most strongly and independently, of all inflammatory factors, associated with IL-6 release, whereas complement activation partly offsets the myocardial depression of the syndrome. Innate immunity factors may thus differ in their contribution to the course of hemodynamic abnormalities of septic shock.

Early recovery in hemodynamics after direct hemoperfusion with polymyxin B-immobilized fibers may predict mortality rate in patients with septic shock

PURPOSE

This retrospective and observational study attempted to determine whether the rapid improvement in hemodynamic parameters and the subsequent discontinuation or decrease of catecholamine infusion shortly after direct hemoperfusion with polymyxin B-immobilized fibers (PMX) may be strong predictors of mortality in patients with septic shock.

METHODS

Retrospectively, 46 patients were divided into two groups; those who survived more than 30 days after PMX (survival group, S group) and those who died within 30 days (nonsurvival group, NS group). Sequential Organ Failure Assessment (SOFA) scores, mean arterial pressure, catecholamine index (CAI), and vasopressor dependency index (VDI) were examined before and after PMX. The same parameters were examined on days 3, 4, 5, 6, 8, and 16 after PMX.

RESULTS

CAI in the S group significantly decreased from 14.7 (95% CI, 10.3-19.1) at baseline to 6.4 (95% CI, 3.7-9.2; P < 0.001) at post-PMX, whereas a significant decrease in CAI was not observed in the NS group (23.1; 95% CI, 15.4-30.7 to 18.1; 95% CI, 11.6-24.7; P = 0.114). The significant decrease in VDI at post-PMX was observed both in the S group and in the NS group. If the cutoff point of VDI at post-PMX is 0.2, there is a significant difference in numbers of the S group (VDI ≥ 0.2, n = 24; VDI < 0.2, n = 2) and NS group (VDI ≥ 0.2, n = 8; VDI < 0.2, n = 20) using Fisher's exact test.

CONCLUSIONS

We concluded that the early improvement in CAI and VDI shortly after PMX might be prognostic indicators for survival.

Hemodynamics in preterm infants with late-onset sepsis

OBJECTIVE

To describe the hemodynamic changes with time in preterm infants with clinical sepsis.

STUDY DESIGN

Blood pressure, right ventricular output (RVO), left ventricular output (LVO), and superior vena cava (SVC) flow of infants who had a suspected infection and showed signs of cardiovascular compromise were measured every 12 hours or until there was considered clinical improvement.

RESULTS

Twenty infants with a median gestational age of 27 weeks (range, 25-32 weeks) and weight of 995 g (range, 650-1980 g) were examined. Five patients died. The mean (SD) RVO, LVO, and SVC flow at the first measurement were 555 (133), 441 (164), and 104 (39) mL/kg/min, respectively. The calculated systemic vascular resistance (SVR) was 0.08 (0.04) mm Hg/mL/kg/min. There was no significant change in flow in the 15 surviving infants. Blood pressure and SVR increased from the first to the last measurement (mean difference: blood pressure, 8 mm Hg; 95% CI 3 to -13; systemic vascular resistance, 0.02 mm Hg/mL/kg/min; 95% CI, 0.01 to -0.04). Flows decreased and SVR increased in the 5 non-surviving infants (mean difference: RVO, -318 mL/kg/min; 95% CI, -463 to -174; LVO, -292 mL/kg/min; 95% CI, -473 to -111; SVC flow, -46 mL/kg/min; 95% CI, -77 to -16).

CONCLUSION

Preterm neonates with sepsis have relatively high left and right cardiac outputs and low SVRs. A decrease in RVO or LVO >50% compared with the initial measurement is associated with mortality.

Functional echocardiography; from physiology to treatment

Functional echocardiography (fECHO) is the bedside use of ultrasound to longitudinally assess myocardial function, systemic and pulmonary blood flow, and intra and extracardiac shunts. This review will focus on fECHO as a tool for the clinician to assess the hemodynamic condition of sick neonates and describe situations where fECHO can help determine a pathophysiological choice for cardiovascular support. The very low birth weight infant with hypotension during the first 24h of life, assessment and monitoring of the ductus arteriosus, assessment and response to treatment of infants with pulmonary hypertension, the infant with perinatal asphyxia and the infant with sepsis and cardiovascular compromise are reviewed. Close cooperation with pediatric cardiology, proper logistics and training programs are mandatory to achieve a 24h a day fECHO service run by bedside clinicians.

Prognostic value of increased plasma levels of brain natriuretic peptide in patients with septic shock

Our objective was to investigate the plasma levels of brain and atrial natriuretic peptides (BNP and ANP, respectively) in patients with septic shock/severe sepsis and to study the association of BNP and ANP levels with hemodynamic parameters, severity of the disease, and prognosis of those patients. This is a prospective case series study of 22 patients with septic shock, 11 patients with severe sepsis, and 20 healthy volunteers at the Department of Emergency and Critical Care Medicine, Nara Medical University Hospital, Japan. Blood collection was performed on admission and on days 1, 2, and 4. Plasma BNP and ANP levels were measured by radioimmunoassay. Right atrial pressure, mean pulmonary arterial pressure, pulmonary arterial wedge pressure, and left ventricular stroke work index were determined using a thermodilution catheter. Acute Physiological and Chronic Health Evaluation II scores were calculated. Plasma levels of BNP and ANP were markedly elevated in patients with septic shock/severe sepsis compared with controls (BNP, 7 +/- 0.3 pg mL; ANP, 13 +/- 1 pg mL). In patients with septic shock, both BNP and ANP peaked on day 2 (BNP, 987 +/- 160 pg mL; ANP, 103 +/- 17 pg mL). Plasma levels of BNP on day 2 in patients with septic shock significantly correlated with right atrial pressure (r = 0.744, P < 0.01), mean pulmonary arterial pressure (r = 0.670, P < 0.01), pulmonary arterial wedge pressure (r = 0.709, P < 0.01), left ventricular stroke work index (r = -0.552, P < 0.05), Acute Physiological and Chronic Health Evaluation II score (r = 0.581, P < 0.01), and poor prognosis (P < 0.05). The optimal cutoff point for predicting mortality in patients with septic shock was a BNP level of 650 pg mL on day 2, in which sensitivity and specificity were 92% and 80%, respectively. Increased plasma levels of BNP may reflect not only the severity of myocardial depression but also the disease severity and could be of prognostic value in patients with septic shock.

Myocardial dysfunction in meningococcal septic shock

PURPOSE OF REVIEW

The underlying pathophysiology of sepsis has long been disputed. Systemic vasodilatation is important in the development of shock and, in septic critically ill adults who have been volume resuscitated, the systemic pressure is often low and the cardiac output high. In septic children however, and especially in those with meningococcal septic shock, poor cardiac output as a consequence of depressed myocardial function seems to be important, often being the cause of death in these patients. There is much evidence for disturbance of myocardial performance, yet despite the literature, there is still no consensus on how best to manage this complication of meningococcal disease.

RECENT FINDINGS

Many mediators have been proposed as the cause of the reduced myocardial performance, most recently interleukin-6 has emerged as a possible candidate involved in the pathophysiology of the myocardial dysfunction. Cardiac troponin I has been shown to be a marker of myocardial injury and may be used to monitor left ventricular function. Newer treatments emerging to manage the dysfunction include reports of success with phosphodiesterase inhibitors.

SUMMARY

Accepting that myocardial dysfunction may be an important cause of the shock state in overwhelming meningococcal disease, the approach to management may need to be tailored appropriately. Although presently there is no targeted treatment, it may be that therapy focused on inhibiting or antagonising interleukin-6 will be helpful in the future. Regardless of the importance of myocardial depression, fluid resuscitation remains a cornerstone in the management of severe meningococcal disease.

Interleukin-6 Causes Myocardial Failure and Skeletal Muscle Atrophy in Rats

Background— The impact of interleukin (IL)-6 on skeletal muscle function remains the subject of controversy.

Methods and Results— The effects of 7-day subcutaneous administration of recombinant human IL-6 were examined at 3 doses, 50, 100, or 250 μg · kg −1 · d −1 , in rats. Skeletal muscle mass decreased dose-dependently (with increasing dose: in the diaphragm, −10%, P =NS; −15%, P =0.0561; and −15% P <0.05; and in the gastrocnemius, −9%, P =NS; −9%, P =NS; and −18%, P <0.005) because of decreases in cross-sectional area of all fiber types without alterations in diaphragm contractile properties. Cardiovascular variables showed a dose-dependent heart dilatation (for end-diastolic volume: control, 78 μL; moderate dose, 123 μL; and high dose, 137 μL, P <0.001), reduced end-systolic pressure (control, 113 mm Hg; moderate dose, 87 mm Hg; and high dose, 90 mm Hg; P =0.037), and decreased myocardial contractility (for preload recruitable stroke work: control, 79 mm Hg; moderate dose, 67 mm Hg; and high dose, 48 mm Hg; P <0.001). Lung edema was confirmed by an increased wet-to-dry ratio (control, 4.2; moderate dose, 4.6; and high dose, 4.5; P <0.001) and microscopy findings. These cardiovascular alterations led to decreases in organ blood flow, particularly in the diaphragm (control, 0.56 mL · min −1 · g −1 ; moderate dose, 0.21 mL · min −1 · g −1 ; and high dose, 0.23 mL · min −1 · g −1 ; P =0.037). In vitro recombinant human IL-6 administration did not cause any alterations in diaphragm force or endurance capacity.

Conclusions— IL-6 clearly caused ventilatory and peripheral skeletal muscle atrophy, even after short-term administration. Blood flow redistribution, resulting from the myocardial failure induced by IL-6, was likely responsible for this muscle atrophy, because IL-6 did not exert any direct effect on the diaphragm.

Dexamethasone improves vascular hyporeactivity induced by LPS in vivo by modulating ATP-sensitive potassium channels activity

(1) Septic shock represents an important risk factor for patients critically ill. This pathology has been largely demonstrated to be a result of a myriad of events. Glucocorticoids represent the main pharmacological therapy used in this pathology. (2) Previously we showed that ATP-sensitive potassium (KATP) channels are involved in delayed vascular hyporeactivity in rats (24 h after Escherichia coli lipopolysaccharide (LPS) injection). In LPS-treated rats, we observed a significant hyporeactivity to phenylephrine (PE) that was reverted by glybenclamide (GLB), and a significant increase in cromakalim (CRK)-induced hypotension. (3) We evaluated the effect of dexamethasone (DEX 8 mg kg-1 i.p.) whether on hyporeactivity to PE or on hyperreactivity to CRK administration, in vivo, in a model of LPS (8 x 106 U kg-1 i.p.)-induced endotoxemia in urethane-anaesthetised rats. (4) DEX treatment significantly reduced, in a time-dependent manner, the increased hypotensive effect induced by CRK in LPS-treated rats. This effect was significantly (P<0.05) reverted by the glucocorticoid receptor antagonist RU38486 (6.6 mg kg-1 i.p.). (5) GLB-induced hypertension (40 mg kg-1 i.p.), in LPS-treated rats, was significantly inhibited by DEX if administered at the same time of LPS. (6) Simultaneous administration of DEX and LPS to rats completely abolished the hyporeactivity to PE observed after 24 h from LPS injection. (7) In conclusion, our results suggest that the beneficial effect of DEX in endotoxemia could be ascribed, at least in part, to its ability to interfere with KATP channel activation induced by LPS. This interaction may explain the improvement of vascular reactivity to PE, mediated by DEX, in LPS-treated rats, highlighting a new pharmacological activity to the well-known anti-inflammatory properties of glucocorticoids.

An assessment of fructose-1,6-bisphosphate as an antimicrobial and anti-inflammatory agent in sepsis

Tissue lesion mechanisms provoked by sepsis include the infectious process, inflammation, and cellular energy deficit. We chose to test fructose-1,6-bisphosphate (FBP) because of its possible anti-inflammatory and antimicrobial actions. Wistar rats were used and divided into three experimental groups: a control group (n=10), in which a capsule was introduced into the peritoneum of the animals; a septic group (n=10), in which a capsule containing non-sterile fecal matter was introduced together with Escherichia coli (1.5 x 10(9)CFU); and a septic group treated with FBP 500 mg/kg (n=10). The blood cell tests revealed that levels of leukocytes increased significantly in the septic group when compared to both the septic group treated with FBP and the control group. The blood cultures were 100% positive in both the septic group and the septic group treated with bisphosphorylated sugar. The antibiogram only revealed an inhibitory halo in the case of the antibiotic ampicillin, there was no such indication for FBP. The anti-inflammatory power of FBP remained at 60% for 5 h in the rats that received the carrageenan injection. What is more, the sugar reduced the levels of ionic calcium in relation to the control group. This data proves the validity of using FBP in the treatment of sepsis, possibly due to its anti-inflammatory rather than antimicrobial action.

Physiopathological studies in septic rats and the use of fructose 1,6-bisphosphate as cellular protection

OBJECTIVE

The aim of this research project was to test the ability of fructose 1,6-bisphosphate (FBP), which has anti-inflammatory effects and maintains cellular energy levels, to inhibit the septic process in an experimental model in rats.

DESIGN

Prospective, controlled animal trial.

SETTING

Research laboratory.

SUBJECTS

Fed male Wistar rats.

INTERVENTIONS

Three experimental groups were formed for the test: control group, untreated septic group, and septic group treated with FBP (500 mg/kg).

MEASUREMENTS AND MAIN RESULTS

In the control group, there were no deaths; in the untreated septic group, the mortality rate was 100% within 15 hrs; in the septic group treated with FBP, the mortality rate reached 20% within 15 hrs. The blood cell tests revealed that concentrations of hematocrit, leukocytes, monocytes, and immature cells increased significantly in the untreated septic group compared with both the FBP-treated septic group and the control group. The histologic lesions verified in the heart, lungs, liver, and kidneys of septic animals were smaller and even absent in those treated with FBP.

CONCLUSION

FBP reduced the mortality rate provoked by experimental sepsis and ameliorated hematologic and histologic alterations.

Endotoxin removal by direct hemoperfusion with an adsorbent column using polymyxin B-immobilized fiber ameliorates systemic circulatory disturbance in patients with septic shock

Direct hemoperfusion (DHP) with an adsorbent column using polymyxin B-immobilized fiber (PMX-F) has been shown to improve the state of shock in patients with septic shock. However, no evidence has been presented for a direct link between endotoxin removal by DHP with PMX-F and improvement in septic shock. We retrospectively analyzed clinical profiles of 24 patients with septic shock (16 patients, gram-negative; 8 patients, non-gram-negative septic shock) who underwent DHP with PMX-F. Patients with gram-negative septic shock were characterized by hyperdynamic circulation. DHP with PMX-F reduced blood endotoxin concentrations and ameliorated shock, with an improvement in hyperdynamic circulation in patients with gram-negative septic shock. Mean arterial pressure also was elevated after therapy in patients with non-gram-negative septic shock, but systemic hemodynamics were unaffected. Regardless of the causative microorganism, patients with endotoxemia (blood endotoxin level > 10 pg/mL) showed hyperdynamic shock, and DHP with PMX-F reduced blood endotoxin levels and ameliorated hyperdynamic circulation, whereas patients without endotoxemia showed features of shock without hyperdynamic circulation, and DHP with PMX-F ameliorated shock without affecting cardiac performance. In patients with gram-negative septic shock, blood endotoxin concentration correlated positively with cardiac output and negatively with systemic vascular resistance before DHP therapy. Reduction in blood endotoxin concentration by DHP therapy positively correlated with the reduction in cardiac output. Our findings indicate that the improvement in hyperdynamic circulation was related directly to endotoxin removal by the PMX-F column, and endotoxin has an important role in the development of hyperdynamic circulation in patients with gram-negative septic shock.

Cytoprotective role of taurine in a renal epithelial cell culture model

Taurine (TAU) is a sulfur-containing amino acid that has been shown to decrease during aging and is believed to be important for cytoprotection. A decrease in TAU could exacerbate the accumulation of free radical-induced damage that may lead to cell death during the aging process. We have shown previously that TAU directly inhibits dopamine (DA) and (-)-3-(3,4-dihydroxyphenyl)-L-alanine (L-dopa) oxidation. Experiments were conducted to establish a cytoprotective role for TAU. Porcine renal epithelial cells were treated for 1 hr with iron and catecholamines (L-dopa and DA) to produce cytotoxicity by a free radical and quinone mechanism in the absence and presence of 10 or 20mM TAU. Viability assays, protein, and DNA measurements were performed after a 24hr recovery period. In some experiments, cells were extracted immediately after the insult for DA and TAU content measurements using high performance liquid chromatography with electrochemical detection. Catecholamine-induced cytotoxicity caused a 50% loss in cell viability, and 10 or 20mM TAU provided significant protection from cytotoxicity and maintained the functional integrity of the cells. Photomicrographs showed attenuation in cell loss and swelling in the presence of TAU. Pretreatment with 1mM TAU followed by exposure to iron and L-dopa in the presence of 1mM TAU caused a moderate but non-significant increase in cell survival. These data conclusively show that TAU can play a cytoprotective role in the LLC-PK(1) cell culture model.

Vascular cell adhesion molecule--1 expression is obligatory for endotoxin-induced myocardial neutrophil accumulation and contractile dysfunction

BACKGROUND

Sepsis-induced cardiac dysfunction occurs commonly in critically ill patients and is associated with high mortality rates. Neutrophils play a central role in sepsis-induced lung and liver injury; however, the mechanism of sepsis-induced cardiac dysfunction remains unclear. Vascular cell adhesion molecule-1 (VCAM-1) has been implicated in neutrophil-mediated liver injury during endotoxemia and is also expressed in myocardium. The purposes of this study were to examine the temporal relationship of myocardial VCAM-1 expression with neutrophil accumulation during endotoxemia and to determine whether VCAM-1 mediates neutrophil accumulation and cardiac dysfunction during endotoxemia.

METHODS

Mice were subjected to lipopolysaccharide (LPS; 0.5 mg/kg, intraperitoneally). Myocardial VCAM-1 expression and neutrophil accumulation were determined by immunofluorescence staining. Cardiac performance with or without VCAM-1 blocking antibody (5 mg/kg, intravenously) was determined by the Langendorff technique.

RESULTS

LPS caused a time-dependent increase in both myocardial VCAM-1 expression and neutrophil accumulation. At 6 hours after LPS, the immunofluorescent intensity for VCAM-1 increased from 2.5 +/- 0.6 x 10(6) in saline solution controls to 19.9 +/- 3.5 x 10(6) (P <.05, analysis of variance), and neutrophil count increased from 2.4 +/- 1.7/mm(2) in saline solution controls to 13.0 +/- 2.5/mm(2) (P <.05). Left ventricular developed pressure was decreased maximally at 6 hours after LPS compared with saline solution controls (29.1 +/- 1.1 mm Hg vs 53.1 +/- 3.9 mm Hg; P <.05). Treatment with VCAM-1 monoclonal antibody abrogated both myocardial neutrophil accumulation and cardiac dysfunction during endotoxemia.

CONCLUSIONS

LPS-induced myocardial dysfunction is associated with increased expression of VCAM-1 and with neutrophil accumulation. Blockade of VCAM-1 abrogates myocardial neutrophil accumulation and preserves cardiac function during endotoxemia, which supports a role for VCAM-1 as a therapeutic target for myocardial protection during sepsis.

The severity of hyperdynamic circulation may predict the effects of direct hemoperfusion with the adsorbent column using polymyxin B-immobilized fiber in patients with gram-negative septic shock

It has been reported that direct hemoperfusion with the adsorbent column using polymyxin B-immobilized fiber (DHP with PMX-F column) ameliorates hyperdynamic circulation in septic shock and improves survival rate. However, the clinical characteristics of patients with an improvement of septic shock after DHP with PMX-F column have not been evaluated. To clarify this issue, the clinical profiles of 46 patients who were suggested to have gram-negative septic shock and treated using DHP with PMX-F column were analyzed retrospectively. Of 46 patients, 31 were diagnosed with gram-negative septic shock (G group). Mean arterial pressure (MAP) just before DHP with PMX-F column was not different between the G and the non-G group. As compared with the non-G group, the G group had a higher cardiac index (CI) and a lower systemic vascular resistance (SVR). Significant increases in MAP and SVR with a significant decrease in CI were observed after DHP with PMX-F column in the G group. In the non-G group, MAP was significantly increased after the DHP therapy, but systemic hemodynamics were unchanged. Patients in the G group who fulfilled the following criteria were considered as the effective group: MAP was elevated more than 10 mm Hg or 125% of the basal MAP and/or the dose of vasopressors was reduced after DHP with PMX-F column. Twenty-one patients (67.8%) were in the effective group. In comparison with the effective group, the noneffective group was characterized by a significant increase in CI before DHP with PMX-F column. All patients with a CI less than 6 L/min/m2 were in the effective group. These data suggest that DHP with PMX-F column was useful for patients with gram-negative septic shock who did not have severe hyperdynamic circulation.

alpha-atrial natriuretic peptide, cyclic guanosine monophosphate, and endothelin in plasma as markers of myocardial depression in human septic shock

OBJECTIVE

To assess the value of alpha-atrial natriuretic peptide (alpha-ANP), second messenger cyclic guanosine monophosphate (cGMP,) and endothelin as markers of myocardial depression in septic shock.

DESIGN

Prospective observational study.

SETTING

Medical intensive care unit (ICU) of a university hospital.

PATIENTS

Fourteen consecutive patients with septic shock and arterial and pulmonary artery catheters in place.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic variables and plasma levels of alpha-ANP, cGMP, and endothelin were measured every 6 hrs for 3 days after admission. Eight patients died from shock in the ICU. The nadir left ventricular stroke work index (LVSWI) was below 35 g/m2 in all patients, and the median peak circulating alpha-ANP (n < 68 pg/mL) was 276 pg/mL (range, 79-1056), the median peak cGMP (n < 2.1 ng/mL) was 8.1 ng/mL (range, 3.2-29.7), and the median peak endothelin (n < 5.3 pg/mL) was 15.5 pg/mL (range, 8.5-33.9), supranormal in all patients. Outcome groups differed in the course of cardiac index and LVSWI, which were lower in nonsurvivors despite similar filling pressures and more intensive inotropic treatment (p < .01). The course of alpha-ANP, cGMP, and endothelin plasma levels also differed between groups, with higher levels in nonsurvivors (p < .05). As for pooled data, the mean daily or nadir LVSWI inversely related to mean daily or peak alpha-ANP, cGMP, and endothelin levels, respectively (p < .05). The area under the receiver operating characteristic curve for myocardial depression (LVSWI < 35 g/m2) was for alpha-ANP and endothelin 0.77, and for cGMP 0.85 (p < .01). The optimum cutoff values for alpha-ANP, cGMP, and endothelin were 172 pg/mL, 4.5 ng/mL, and 10.0 pg/mL, respectively. The sensitivity for myocardial depression of alpha-ANP, cGMP, and endothelin was 68%, 77%, and 72%, and the specificity was 82%, 93%, and 69%, respectively.

CONCLUSIONS

Circulating alpha-ANP, endothelin, and, particularly, cGMP may be markers of the myocardial depression of human septic shock, which is associated with mortality.

Nitric oxide indices in human septic shock

OBJECTIVES

To study the relation between nitrite, nitrate, nitrotyrosine, and nitrosothiols as NO indices in human septic shock.

DESIGN

A prospective clinical study.

SETTING

Intensive care units in a university hospital and a central county hospital.

PATIENTS

Sixteen patients admitted for septic shock. Nine healthy volunteers served as controls.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Patients with septic shock had a hyperdynamic circulatory response and required infusion of at least two vasopressors to maintain systemic blood pressure. Four episodes of recurrent shock occurred in two patients. Heparinized plasma was collected once daily for analysis of NO indices. Peak plasma concentrations of nitrite + nitrate (NOx) were elevated in first episodes of septic shock; 144+/-39 microM vs. controls, 20+/-3 microM (p < .05). Peak plasma NOx concentrations in recurrent shocks were; 160+/-19 microM. Peak plasma concentrations of 3-nitrotyrosine (NT) were elevated in primary septic shock 102+/-19 pmol x mL(-1) vs. controls 14+/-6 pmol x mL(-1) (p < .05). Peak NT concentrations were 117+/-37 pmol x mL(-1) in recurrent septic shock. Peak plasma NT concentrations did not coincide with peak NOx concentrations in half of the episodes of septic shock. Plasma NT was elevated (59+/-15 pmol x mL(-1) vs. controls 14+/-6 pmol x mL(-1), p < .05) in patients with normal plasma NOx concentrations throughout septic shock. Plasma concentrations of nitrosothiols did not change during septic shock.

CONCLUSIONS

Plasma concentrations of NOx and NT are elevated in primary episodes of septic shock and may also be elevated in secondary septic shock, but too few episodes of recurrent septic shock occurred to allow firm conclusions. Plasma concentrations of NT are elevated in patients with septic shock with normal plasma NOx concentrations, indicating that plasma concentrations of NOx may not always accurately reflect NO production. Reactive nitrogen species may be formed in septic shock, and measuring both NOx and NT may give a better indication of NO production in septic shock than NOx alone. Plasma levels of nitrosothiols did not change during septic shock.

Blockade of the action of nitric oxide in human septic shock increases systemic vascular resistance and has detrimental effects on pulmonary function after a short infusion of methylene blue

To investigate the role of nitric oxide in human sepsis, ten patients with severe septic shock requiring vasoactive drug therapy and mechanical ventilation were enrolled in a prospective, open, non-randomized clinical trial to study the acute effects of methylene blue, an inhibitor of guanylate cyclase. Hemodynamic and metabolic variables were measured before and 20, 40, 60, and 120 min after the start of a 1-h intravenous infusion of 4 mg/kg of methylene blue. Methylene blue administration caused a progressive increase in mean arterial pressure (60 [55-70] to 70 [65-100] mmHg, median [25-75th percentiles]; P<0.05), systemic vascular resistance index (649 [479-1084] to 1066 [585-1356] dyne s-1 cm-5 m-2; P<0.05) and the left ventricular stroke work index (35 [27-47] to 38 [32-56] g m-1 m-2; P<0.05) from baseline to 60 min. The pulmonary vascular resistance index increased from 150 [83-207] to 186 [121-367] dyne s-1 cm-5 m-2 after 20 min (P<0.05). Mixed venous saturation decreased from 65 [56-76] to 63 [55-69]% (P<0.05) after 60 min. The PaO2/FiO2 ratio decreased from 168 [131-215] to 132 [109-156] mmHg (P<0.05) after 40 min. Arterial lactate concentration decreased from 5.1 +/- 2.9 to 4.5 +/- 2.1 mmol/l, mean +/- SD (P<0.05) after 60 min. Heart rate, cardiac filling pressures, cardiac output, oxygen delivery and consumption did not change. Methylene blue administration was safe and no adverse effect was observed. In severe human septic shock, a short infusion of methylene blue increases systemic vascular resistance and may improve myocardial function. Although there was a reduction in blood lactate concentration, this was not explained by an improvement in tissue oxygenation, since overall oxygen availability did not change. However, there was a significant increase in pulmonary vascular tone and a deterioration in gas exchange. Further studies are needed to demonstrate if nitric oxide blockade with methylene blue can be safe for patients with septic shock and, particularly, if it has an effect on pulmonary function.

Persistent preload defect in severe sepsis despite fluid loading: A longitudinal echocardiographic study in patients with septic shock

STUDY OBJECTIVE

To investigate the rate of recovery from septic shock in patients with suspected left ventricular (LV) preload deficiency and LV systolic dysfunction.

DESIGN

A monitoring period was defined by the need for inotropic/vasopressor support, and LV function was assessed daily during this period by bedside two-dimensional echocardiography (2D-ECHO).

SETTING

University hospital ICU.

PATIENTS

During a 5-year period, 90 patients with an episode of septic shock (60% with gram-positive bacteria as the causative agent) were consecutively enrolled in the study (mean age, 55 +/- 18 years). Standard volume resuscitation combined with inotropic/vasopressor support was used to maintain systolic arterial pressure > 90 mm Hg. All patients received mechanical ventilation because of associated respiratory failure. The average duration of hemodynamic support was 4.4 +/- 1.6 days. Thirty-four patients were weaned from hemodynamic support during the monitoring period and ultimately recovered (group I). Twenty-eight patients died from refractory circulatory failure during the monitoring period, and 28 died later from ARDS or multiple organ dysfunction syndrome, leading to a 62% overall mortality rate (group II).

METHODS

Daily bedside LV volumes and ejection fraction (LVEF) were recorded using 2D-ECHO. Data obtained at the start (day 1 and day 2) and end of the monitoring period (day n) were compared.

RESULTS

LV end-diastolic volume was within the normal range of our laboratory values in all patients, but was initially smaller in group II than in group I, and remained so despite fluid loading. LVEF was significantly depressed in all patients, resulting in severe reduction in LV stroke volume (LVSV), which was initially more marked in group I. In group I patients, LVEF significantly improved during the monitoring period, resulting in an increase in LVSV.

CONCLUSION

2D-ECHO changes during hemodynamic support in 90 septic patients confirmed defective LV preload with a propensity to worsen despite fluid loading in nonsurvivors (62% in the present study). Our results are also in agreement with previous studies reporting depressed LV systolic function at the initial phase of septic shock. Since LV dysfunction was more marked in patients who recovered, we suggest that the exact significance of this finding should be reevaluated.

Stress doses of hydrocortisone reverse hyperdynamic septic shock: a prospective, randomized, double-blind, single-center study

OBJECTIVE

To investigate the effects of stress doses of hydrocortisone on the duration of vasopressor therapy in human septic shock.

DESIGN

Prospective, randomized, double-blind, single-center study.

SETTING

Twenty-bed multidisciplinary intensive care unit in a 1400-bed university hospital.

PATIENTS

Forty consecutive patients who met the ACCP/SCCM criteria for septic shock. An additional criterion for inclusion in the study was vasopressor support and high-output circulatory failure with a cardiac index of >4 L/min/m2 after fluid resuscitation (pulmonary capillary wedge pressure: 12-15 mm Hg) and without the use of positive inotropes such as dobutamine or dopexamine. The primary study end point was the time to cessation of vasopressor support (norepinephrine or epinephrine in any dose, dopamine > or = 6 microg/kg/min). Secondary study end points were the evolution of hemodynamics and the multiple organ dysfunction syndrome (MODS). The severity of illness at recruitment was graded using the Acute Physiology and Chronic Health Evaluation II and the Simplified Acute Physiology Score II scoring systems. MODS was described by the Sepsis-related Organ Failure Assessment score.

INTERVENTIONS

All eligible patients were prospectively randomized to receive either stress doses of hydrocortisone or placebo. Hydrocortisone was started with a loading dose of 100 mg given within 30 mins and followed by a continuous infusion of 0.18 mg/ kg/hr. When septic shock had been reversed, the dose of hydrocortisone was reduced to 0.08 mg/kg/hr. This dose was kept constant for 6 days. As soon as the underlying infection had been treated successfully or sodium serum concentrations had increased to >155 mmol/L, the hydrocortisone infusion was tapered in steps of 24 mg/day. Physiologic saline solution was the placebo.

MEASUREMENTS AND MAIN RESULTS

Hemodynamic and oxygen-derived variables were measured at previously defined time points over a study period of 5 days. Relevant clinical and laboratory measurements were registered for a study period of 14 days to assess the evolution of organ dysfunction. Baseline data at recruitment did not differ between the two groups. Shock reversal was achieved in 18 of the 20 patients treated with hydrocortisone vs. 16 of the 20 patients treated with placebo. Hydrocortisone significantly reduced the time to cessation of vasopressor support. The median time of vasopressor support was 2 days (1st and 3rd Quartiles, 1 and 6 days) in the hydrocortisone-treated group and 7 days (1st and 3rd Quartiles, 3 and 19 days) in the placebo group (p = .005 Breslow test). There was a trend to earlier resolution of the organ dysfunction syndrome in the hydrocortisone group.

CONCLUSIONS

Infusion of stress doses of hydrocortisone reduced the time to cessation of vasopressor therapy in human septic shock. This was associated with a trend to earlier resolution of sepsis-induced organ dysfunctions. Overall shock reversal and mortality were not significantly different between the groups in this low-sized single-center study.

Has the mortality of septic shock changed with time

OBJECTIVES

To determine whether a systematic review of the literature could identify changes in the mortality of septic shock over time.

DATA SOURCES

A review of all relevant papers from 1958 to August 1997, identified through a MEDLINE search and from the bibliographies of articles identified.

DATA SYNTHESIS

The search identified 131 studies (99 prospective and 32 retrospective) involving a total of 10,694 patients. The patients' mean age was 57 yrs with no change over time. The overall mortality rate in the 131 studies was 49.7%. There was an overall significant trend of decreased mortality over the period studied (r=.49, p < .05). The mortality rate in those patients with bacteremia as an entry criterion was greater than that rate in patients whose entry criterion was sepsis without definite bacteremia (52.1% vs. 49.1%; chi2=6.1 and p< .05). The site of infection altered noticeably over the years. Chest-related infections increased over time, with Gram-negative infections becoming proportionately less common. If all other organisms and mixed infections are included with the Gram-positives, the result is more dramatic, with these organisms being causative in just 10% of infections between 1958 and 1979 but in 31% of infections between 1980 and 1997.

CONCLUSIONS

The present review showed a slight reduction in mortality from septic shock over the years, although this result should be approached with caution. The heterogeneity of the articles and absence of a severity score for most of the studies limited our analysis. Furthermore, there was an increasing prevalence of Gram-positive causative organisms, and a change of the predominant origin of sepsis from the abdomen to the chest.

N(G)-monomethyl-L-arginine improves survival in a pig model of abdominal sepsis

OBJECTIVE

To test the effect of a continuous infusion of the nitric oxide synthase inhibitor N(G)-monomethyl-L-arginine (L-NMMA) on survival rate and hemodynamics in a pig model of endogenous peritoneal live bacterial sepsis.

DESIGN

Prospective, randomized trial.

SETTING

Laboratory at a university medical center.

SUBJECTS

Thirty-five pigs with an average weight of 26 kg (range 21 to 33).

INTERVENTIONS

After surgical preparation, animals (control, n=6) given anesthesia and fluids were observed for 9 hrs. Fifteen experimental animals received 0.5 g of cecal content/kg of body weight intraperitoneally after surgery. Nine of these animals received standard anesthesia and fluids and were observed for 9 hrs or until death. Six animals received a continuous infusion of L-NMMA (10 mg/kg/hr) 3 hrs after sepsis induction. Starting 3 hrs after surgery, five nonrandomized animals were given anesthesia and fluids and received a 6-hr continuous infusion of L-NMMA (10 mg/kg/hr). An additional nine animals were anesthetized and blood samples were taken to determine plasma nitrate concentrations in nonoperated pigs.

MEASUREMENTS AND MAIN RESULTS

L-NMMA treatment increased 9-hr survival in septic animals from 11% to 83% (p < .001), prevented a further decrease in mean arterial pressure and restored mean arterial pressure to control levels (p < .00002 vs. nontreated septic animals). Mean pulmonary arterial pressure increased slightly during L-NMMA infusion (p < .0003). Coronary blood flow was preserved during L-NMMA treatment. Cardiac index and urine production reached and maintained control levels during L-NMMA treatment of septic animals. Mean central venous pH did not deteriorate during L-NMMA treatment. Animals treated with L-NMMA had plasma nitrate concentrations similar to nonseptic control animals. The results from the nonseptic control group receiving L-NMMA suggest that a substantial part of the effect of L-NMMA in this model of septic shock may be due to inhibition of the constitutive nitric oxide production.

CONCLUSIONS

In this porcine model of peritoneal sepsis, infusion of L-NMMA increased survival rate and maintained mean arterial pressure without worsening tissue oxygenation. Coronary blood flow, cardiac index, systemic vascular resistance, and urine production were well maintained during L-NMMA treatment.

The hemodynamic derangements in sepsis: implications for treatment strategies

The incidence of the sepsis syndrome has increased dramatically in the last few decades. During this time, we have gained new insights into the pathophysiologic mechanisms leading to organ dysfunction in this syndrome. Yet, despite this increased knowledge and the use of novel therapeutic approaches, the mortality associated with the sepsis syndrome has remained between 30% and 40%. Appropriate antibiotic selection and hemodynamic support remain the cornerstone of treatment of patients with sepsis. Recent studies have failed to demonstrate a global oxygen debt in patients with sepsis. Furthermore, therapy aimed at increasing systemic oxygen delivery has failed to consistently improve patient outcome. The primary aim of the initial phase of resuscitation is to restore an adequate tissue perfusion pressure. Aggressive volume resuscitation is considered the best initial therapy for the cardiovascular instability of sepsis. Vasoactive agents are required in patients who remain hemodynamically unstable or have evidence of tissue hypoxia after adequate volume resuscitation.

Therapy of patients with head injuries: key parameters for management

BACKGROUND

Secondary brain injury, presumed secondary to ischemia, increases the mortality and morbidity of traumatic brain injury. Although many mechanisms appear to be involved, many potential ischemic insults results from changes in readily observable physiologic variables.

METHODS

A focused search of scientific articles published in English to determine what data are available to suggest parameters within which key physiologic variables should be maintained.

RESULTS

Few data demonstrate that maintenance of variables within specific ranges alters outcome; however, considerable evidence establishes association with poor outcome and hypotension, intracranial hypertension, and cerebral venous saturation. Key parameters vary somewhat based upon the phase of treatment after injury. Other variables, such as systemic oxygen delivery and brain saturation measured by near-infrared spectroscopy, are less well linked to outcome.

CONCLUSIONS

Further research is necessary to establish that manipulation of physiologic variables to maintain them within preset ranges improves outcome.

Alterations of myocardial and vascular adrenergic receptor-mediated responses in Escherichia coli-induced septic shock in the rat

OBJECTIVES

To investigate responsiveness to exogenous catecholamines in rat bacteremic shock by studying both myocardial and vascular functional parameters; to determine in the same study the relationship of these parameters with other relevant biological parameters of the adrenergic pathway, such as myocardial beta-adrenergic receptors and cyclic adenosine monophosphate (cAMP); and to indirectly approach the roles of tumor necrosis factor-alpha (TNF-alpha) and nitric oxide.

DESIGN

Experimental, comparative study.

SETTING

Laboratory in a university hospital.

SUBJECTS

Male Sprague-Dawley rats, weighing 270 to 320 g.

INTERVENTIONS

Intravenous injection of live Escherichia coli DH5 alpha (2 x 10(10) organisms/kg) or saline (0.6 mL) and comparison of the two groups.

MEASUREMENTS AND MAIN RESULTS

Mean arterial pressure and heart rate (HR) were recorded, and circulating TNF-alpha concentrations were measured, during the first 3 hrs after E. coli administration. Myocardial and vascular functional parameters were obtained, respectively, from Langendorff-perfused hearts and isolated aortic rings. Adrenergic biochemical parameters (catecholamines, density and affinity of beta-receptors, and isoproterenol-stimulated myocardial cAMP) were determined 3 hrs after E. coli injection. Mean arterial pressure decreased within 5 to 60 mins after bacteria injection and returned to basal levels in the last 2 hrs; HR was unchanged. Serum TNF-alpha concentrations peaked at 120 mins (7333 +/- 672 pg/mL) and were still increased at 3 hrs. Plasma concentrations of epinephrine and norepinephrine were significantly (p < .05) increased. Baseline values for differential left ventricular pressure and coronary flow were significantly (p < .0001, p < .001, respectively) reduced; HR remained unchanged. Isoproterenol induced a similar increase in differential left ventricular pressure and in HR. There was no decrease in the functional myocardial response to adrenergic stimulation. beta-adrenergic receptors were similar in density and in affinity in the two groups. Isoproterenol-stimulated myocardial cAMP was significantly (p < .01) reduced compared with the control group. In aortic rings, bacteria administration significantly (p < .01) shifted the dose-response curve to norepinephrine to the right, both in the presence and absence of endothelium. NG-monomethyl-L-arginine significantly increased the contractions to attain the control level: p < .001 in presence of endothelium; p < .05 in absence of endothelium.

CONCLUSIONS

In ex vivo experiments, 3 hrs after E. coli injection, vascular responsiveness was sharply decreased. This impaired response was improved by inhibition of nitric oxide. The heart, nevertheless, was still able to modulate its inotropic and chronotropic response to isoproterenol, even though an impaired beta-adrenergic-receptor stimulation of cAMP was already present.