Hemodynamic Instability in Sepsis

Activated protein C improves lipopolysaccharide-induced cardiovascular dysfunction by decreasing tissular inflammation and oxidative stress

BACKGROUND

Recombinant human activated Protein C (APC) is used as an adjunctive therapeutic treatment in septic shock. APC seemingly acts on coagulation-inflammation interaction but also by decreasing proinflammatory gene activity, thus inhibiting subsequent production of proinflammatory cytokines, NO and NO-induced mediators, reactive oxygen species production and leukocyte-endothelium interaction. The hemodynamic effects of APC on arterial pressure and cardiac function are now well established in animal models. However, the specific effects of APC on heart and vessels have never been studied.

OBJECTIVES

To investigate the potential protective properties of therapeutic ranges of APC on a rat endotoxic shock model in terms of anti-inflammatory and cytoprotective pathways.

DESIGN

Laboratory investigation.

SETTING

University medical center research laboratory.

INTERVENTIONS

Rats were exposed to lipopolysaccharide (LPS) (10 mg/Kg intravenous). Endotoxic shock was treated with infusion of saline with or without APC (33 microg/kg/h) during 4 hrs. Hemodynamic parameters were continuously assessed and measurements of muscle oxygen partial pressures, NO and superoxide anion (O2(-)) by spin trapping, of NF-kappaB, metalloproteinase-9 (MMP-9) and inducible NO synthase (iNOS) by Western blotting, as well as leukocyte infiltration and MMP-9 activity were performed at both the heart and aorta level (tissue).

MAIN RESULTS

APC partially prevented the reduction of blood pressure induced by LPS and improved both vascular hyporeactivity and myocardial performance. This was associated with a decreased up-regulation of NF-kappaB, iNOS and MMP-9. LPS-induced tissue increases in NO and O2(-) production were decreased by APC. Furthermore, APC decreased tissue leukocyte infiltration/activation as assessed by a decrease in myeloperoxidase and matrix metalloproteinase 9 activity.

CONCLUSIONS

These data suggest that APC improves cardiovascular function: 1) by modulating the endotoxin induced-proinflammatory/prooxidant state, 2) by decreasing endothelial/leukocyte interaction and 3) by favoring stabilization of the extracellular matrix.

Echocardiography practice, training and accreditation in the intensive care: document for the World Interactive Network Focused on Critical Ultrasound (WINFOCUS)

Echocardiography is increasingly used in the management of the critically ill patient as a non-invasive diagnostic and monitoring tool. Whilst in few countries specialized national training schemes for intensive care unit (ICU) echocardiography have been developed, specific guidelines for ICU physicians wishing to incorporate echocardiography into their clinical practice are lacking. Further, existing echocardiography accreditation does not reflect the requirements of the ICU practitioner. The WINFOCUS (World Interactive Network Focused On Critical UltraSound) ECHO-ICU Group drew up a document aimed at providing guidance to individual physicians, trainers and the relevant societies of the requirements for the development of skills in echocardiography in the ICU setting. The document is based on recommendations published by the Royal College of Radiologists, British Society of Echocardiography, European Association of Echocardiography and American Society of Echocardiography, together with international input from established practitioners of ICU echocardiography. The recommendations contained in this document are concerned with theoretical basis of ultrasonography, the practical aspects of building an ICU-based echocardiography service as well as the key components of standard adult TTE and TEE studies to be performed on the ICU. Specific issues regarding echocardiography in different ICU clinical scenarios are then described. Obtaining competence in ICU echocardiography may be achieved in different ways - either through completion of an appropriate fellowship/training scheme, or, where not available, via a staged approach designed to train the practitioner to a level at which they can achieve accreditation. Here, peri-resuscitation focused echocardiography represents the entry level--obtainable through established courses followed by mentored practice. Next, a competence-based modular training programme is proposed: theoretical elements delivered through blended-learning and practical elements acquired in parallel through proctored practice. These all linked with existing national/international echocardiography courses. When completed, it is anticipated that the practitioner will have performed the prerequisite number of studies, and achieved the competency to undertake accreditation (leading to Level 2 competence) via a recognized National or European examination and provide the appropriate required evidence of competency (logbook). Thus, even where appropriate fellowships are not available, with support from the relevant echocardiography bodies, training and subsequently accreditation in ICU echocardiography becomes achievable within the existing framework of current critical care and cardiological practice, and is adaptable to each countrie's needs.

Actual incidence of global left ventricular hypokinesia in adult septic shock

RATIONALE AND OBJECTIVE

To evaluate the actual incidence of global left ventricular hypokinesia in septic shock.

METHOD

All mechanically ventilated patients treated for an episode of septic shock in our unit were studied by transesophageal echocardiography, at least once a day, during the first 3 days of hemodynamic support. In patients who recovered, echocardiography was repeated after weaning from vasoactive agents. Main measurements were obtained from the software of the apparatus. Global left ventricular hypokinesia was defined as a left ventricular ejection fraction of <45%.

MEASUREMENTS AND MAIN RESULTS

During a 3-yr period (January 2004 through December 2006), 67 patients free from previous cardiac disease, and who survived for >48 hrs, were repeatedly studied. Global left ventricular hypokinesia was observed in 26 of these 67 patients at admission (primary hypokinesia) and in 14 after 24 or 48 hrs of hemodynamic support by norepinephrine (secondary hypokinesia), leading to an overall hypokinesia rate of 60%. Left ventricular hypokinesia was partially corrected by dobutamine, added to a reduced dosage of norepinephrine, or by epinephrine. This reversible acute left ventricular dysfunction was not associated with a worse prognosis.

CONCLUSION

Global left ventricular hypokinesia is very frequent in adult septic shock and could be unmasked, in some patients, by norepinephrine treatment. Left ventricular hypokinesia is usually corrected by addition of an inotropic agent to the hemodynamic support.

N-terminal pro-brain natriuretic peptide as an early prognostic factor in cancer patients developing septic shock

INTRODUCTION

The overall prognosis of critically ill patients with cancer has improved during the past decade. The aim of this study was to identify early prognostic factors of intensive care unit (ICU) mortality in patients with cancer.

METHODS

We designed a prospective, consecutive, observational study over a one-year period. Fifty-one cancer patients with septic shock were enrolled.

RESULTS

The ICU mortality rate was 51% (26 deaths). Among the 45 patients who benefited from transthoracic echocardiography evaluation, 17 showed right ventricular dysfunction, 18 showed left ventricular diastolic dysfunction, 18 showed left ventricular systolic dysfunction, and 11 did not show any cardiac dysfunction. During the first three days of ICU course, N-terminal pro-brain natriuretic peptide (NT-proBNP) levels were significantly higher in patients presenting cardiac dysfunctions compared to patients without any cardiac dysfunction. Multivariate analysis discriminated early prognostic factors (within the first 24 hours after the septic shock diagnosis). ICU mortality was independently associated with NT-proBNP levels at day 2 (odds ratio, 1.2; 95% confidence interval, 1.004 to 1.32; p = 0.022). An NT-proBNP level of more than 6,624 pg/ml predicted ICU mortality with a sensitivity of 86%, a specificity of 77%, a positive predictive value of 79%, a negative predictive value of 85%, and an accuracy of 81%.

CONCLUSION

We observed that critically ill cancer patients with septic shock have an approximately 50% chance of survival to ICU discharge. NT-proBNP was independently associated with ICU mortality within the first 24 hours. NT-proBNP could be a useful tool for detecting high-risk cancer patients within the first 24 hours after septic shock diagnosis.

Echocardiographic features, mortality, and adrenal function in patients with cirrhosis and septic shock

OBJECTIVES

Cirrhosis of the liver is associated with an increased susceptibility to bacterial infections capable of causing septic shock and with a basal hyperdynamic circulatory state. The primary objective of this study was to delineate the echocardiographic characteristics and outcomes of septic shock in patients with liver cirrhosis. The secondary objective was to determine whether adrenal insufficiency, which may contribute to hyperdynamic syndrome, was more marked in patients with cirrhosis than in other patients with septic shock.

DESIGN

Prospective single-center cohort study.

PATIENTS AND METHODS

Thirty-four patients admitted to the intensive care unit (ICU) for septic shocks were included, 14 with and 20 without liver cirrhosis. Echocardiography was performed within the first 24 h to measure the cardiac index (CI), systolic index (SI), and left ventricular ejection fraction (LVEF). A Synacthen test was performed.

RESULTS

Patients with cirrhosis had higher values for the CI (3.69+/-1.0 vs. 2.86+/-0.8 l/min/m(2); P=0.02), SI (37.5+/-8 vs. 32.4+/-7 ml/m(2); P=0.04), and LVEF (67+/-7 vs. 55.9+/-12%; P=0.005). ICU mortality was 53% overall, 64% in patients with cirrhosis, and 45% in patients without cirrhosis (P=0.27). Serum cortisol levels under basal conditions (H0) and after stimulation (H1) showed no significant differences between patients with and without cirrhosis. The proportion of patients with no response to Synacthen was 77% among patients with cirrhosis and 50% among patients without cirrhosis (P=0.18).

CONCLUSION

In a population with septic shock, left ventricular function was more hyperdynamic in the subset with cirrhosis. Relative adrenal insufficiency occurred in similar proportions of patients with and without cirrhosis.

Cardiac morphological and functional changes during early septic shock: a transesophageal echocardiographic study

OBJECTIVE

The objective was to prospectively evaluate cardiac morphological and functional changes using transesophageal echocardiography (TEE) during early septic shock.

DESIGN

Prospective, observational study.

SETTING

Medical-surgical intensive care unit of a teaching hospital.

PATIENTS AND PARTICIPANTS

Ventilated patients with septic shock, sinus rhythm and no cardiac disease underwent TEE within 12h of admission (Day0), after stabilization of hemodynamics by fluid loading (median volume: 4.9l [lower and upper quartiles: 3.7-9.6l]) and vasopressor therapy, and after vasopressors were stopped (Dayn).

MEASUREMENTS AND RESULTS

Thirty-five patients were studied (median age: 60 years [range 44-68]; SAPS II: 53 [46-62]; SOFA score: 9 [8-11]) and 9 of them (26%) died while on vasopressors. None of the patients exhibited TEE findings of cardiac preload dependence. Between Day0 and Dayn (7 days [range 6-9]), mean left ventricular (LV) ejection fraction (EF) increased (47 +/- 20 vs. 57 +/- 14%: p < 0.05), whereas mean LV end-diastolic volume decreased (97 +/- 25 vs. 75 +/- 20ml: p < 0.0001). Out of 16 patients (46%) with LV systolic dysfunction on Day0, 12 had normal LVEF on Dayn and 4 patients fully recovered by Day28. Only 4 women had LV dilatation (range, LV end-diastolic volume: 110-148ml) on Day0, but none on Dayn. Doppler tissue imaging identified an LV diastolic dysfunction in 7 patients (20%) on Day0 (3 with normal LVEF), which resolved on Dayn.

CONCLUSIONS

This study confirms that LV systolic and diastolic dysfunctions are frequent, but LV dilatation is uncommon in fluid-loaded septic patients on vasopressors. All abnormalities regressed in survivors, regardless of their severity.

DESCRIPTORS

Shock: clinical studies (38), Cardiovascular monitoring (34).

Efficacy of therapeutic hypothermia after out-of-hospital cardiac arrest due to ventricular fibrillation

AIM OF THE STUDY

We investigated implementation and efficacy of mild therapeutic hypothermia in the treatment of out-of-hospital cardiac arrest due to ventricular fibrillation.

MATERIALS AND METHODS

Two periods were compared, an historical one (36 patients) between 2000 and 2002 where therapeutic hypothermia was never used, and a recent period (32 patients) between 2003 and 2005 where therapeutic hypothermia (32-34 degrees C) was implemented prospectively in our unit. Cooling was obtained by simply using wet cloths and ice packs. Survival in the two groups and factors associated with survival were analysed, together with the neurological prognosis in discharged patients.

RESULTS

Survival was significantly higher in the hypothermia group (56% versus 36%), whereas no significant difference was observed in severity between the two periods. Only age, time from return to spontaneous circulation <20min, and therapeutic hypothermia were independently associated with survival. Therapeutic hypothermia was well tolerated and was associated with a significant improvement in neurological outcome. Whereas only 23% of patients actually reached the target temperature in 2003, 100% did in 2005.

CONCLUSION

Therapeutic hypothermia is efficient in significantly improving survival and neurological outcome of out-of-hospital cardiac arrest with ventricular fibrillation. By using a simple method, it can be implemented easily and quickly, without side effects.

Relationship between the tricuspid annular plane systolic excursion and right and left ventricular function in critically ill patients

OBJECTIVE

Echocardiographic recording of the tricuspid annular plane systolic excursion (TAPSE) has been recommended for assessing right ventricular function in cardiac patients. The ability of TAPSE to reflect right ventricular function at baseline and to monitor acute changes in right ventricular function was tested in critically ill patients.

DESIGN

Prospective study.

SETTING

A 24-bed medical intensive care unit.

PATIENTS

Eighty-six patients admitted for acute respiratory failure, circulatory failure, or coma.

INTERVENTIONS

In 40 patients, the examination was repeated after volume expansion (n = 15), passive leg raising (n = 5), or dobutamine infusion (n = 20).

MEASUREMENTS AND RESULTS

The right ventricular fractional area change, TAPSE, the left ventricular ejection fraction, and the ratio of right to left ventricular end-diastolic area were measured using Doppler echocardiography. In the overall population, TAPSE (19+/-5 mm) was positively related to left ventricular ejection fraction (r2 = 0.31, p < 0.001) and right ventricular fractional area change and was negatively related to age and to the ratio of right to left ventricular end-diastolic area. Multivariate analysis indicated that only left ventricular ejection fraction and age were independently related to TAPSE (multiple r2 = 0.36, p < 0.001). Following dynamic interventions, the changes in TAPSE were linearly related to changes in left ventricular ejection fraction (r2 = 0.65, p < 0.01) but notto changes in the right ventricular fractional area change.

CONCLUSIONS

Unexpectedly, TAPSE was more strongly related to left ventricular ejection fraction than to indices of right ventricular function in critically ill patients. The potential interest of TAPSE as a dynamic marker of left ventricular systolic function deserves further study.

Prone positioning unloads the right ventricle in severe ARDS

BACKGROUND

Despite airway pressure limitation, acute cor pulmonale persists in a minority of ARDS patients. Insufficient airway pressure limitation, hypercapnia, or both may be responsible. Because prone positioning (PP) has been shown to be a safe way to reduce airway pressure and to improve alveolar ventilation, we decided to assess its effect on right ventricular (RV) pressure overload in ARDS patients.

METHODS

Between January 1998 and December 2006, we studied 42 ARDS patients treated by PP to correct severe oxygenation impairment (Pao2/fraction of inspired oxygen ratio, <100 mm Hg). RV function was evaluated by bedside transesophageal echocardiography, before and after 18 h of prone-position ventilation. RV enlargement was measured by RV/left ventricular (LV) end-diastolic area ratio in the long axis. Septal dyskinesia was quantified by measuring short-axis systolic eccentricity of the LV.

RESULTS

Before PP, 21 patients (50%) had acute cor pulmonale, defined by RV enlargement associated with septal dyskinesia (group 1), whereas 21 patients had a normal RV (group 2). PP was accompanied by a significant decrease in airway pressure and Paco2. In group 1, this produced a significant decrease in mean (+/-SD) RV enlargement (from 0.91+/-0.22 to 0.61+/-0.21) after 18 h of PP (p=0.000) and a significant reduction in mean septal dyskinesia (from 1.5+/-0.2 to 1.1+/-0.1) after 18 h of PP (p=0.000).

CONCLUSION

In the most severe forms of ARDS, PP was an efficient means of controlling RV pressure overload.

Validation of a skills assessment scoring system for transesophageal echocardiographic monitoring of hemodynamics

OBJECTIVE

Transesophageal echocardiography (TEE) is increasingly used in hemodynamic monitoring in the intensive care unit. This paper describes and validates a scoring system for assessing competence in TEE performed by intensivists for this indication.

DESIGN

Prospective study over an 18-month period.

SETTINGS

Two medical intensive care units.

METHODS

The scoring system is used to assess four aspects of TEE: quality of the views (score out of 14); semiquantitative evaluation of respiratory variations in the superior vena cava, valve regurgitation, size of the right ventricle (score out of 10); accuracy of measurement of velocity-time integrals for pulmonary and aortic flow, peak velocity of the E and A waves of mitral flow, left ventricular fractional area change (score out of 8); summary and proposed treatment (score out of 8). The scoring system was validated by using it to assess intensivists after 1 month (M1), 3 months (M3) and 6 months (M6) of training. TEE was done on a mechanically ventilated, hypotensive patient and scored by comparing the intensivist's examination with that of the expert examiner. The intensivists were divided into two groups of theoretical expertise at the start of training.

RESULTS

Nineteen intensivists were evaluated. The scores at M1 for level 0 (no experience in echocardiography) and level 1 (previous experience) were, respectively, 18.5 +/- 4 and 24.7 +/- 5. The scores at M1, M3, and M6 were, respectively, 20.4 +/- 5, 30.4 +/- 5 and 35.7 +/- 3. At M6, the intensivists had performed TEE 29 +/- 10 times.

CONCLUSION

The scoring system was discriminatory and sensitive to change, and could be used as a tool to assess an intensivist's mastery of TEE.

Pericardiotomy and right ventricular failure: a case report

A 57-year-old woman developed cardiogenic shock secondary to right ventricular failure in the postoperative setting. Because of clinical suspicion of pulmonary embolism, the patient was taken to the operating room for emergency thrombectomy. The patient improved dramatically after sternotomy and pericardiotomy, with no evidence of thrombus being found. Sternotomy followed by pericardiotomy may have a role in the treatment of acute right ventricular failure with small pericardial effusion.

Knockout of Mkp-1 enhances the host inflammatory responses to gram-positive bacteria

MAPK phosphatase (MKP)-1 is an archetypal member of the dual specificity protein phosphatase family that dephosphorylates MAPK. We have previously demonstrated that MKP-1 acts as a negative regulator of p38 and JNK in immortalized macrophages after stimulation with peptidoglycan isolated from Gram-positive bacteria. To define the physiological function of MKP-1 during Gram-positive bacterial infection, we studied the innate immune responses to Gram-positive bacteria using Mkp-1 knockout (KO) mice. We found that Mkp-1(-/-) macrophages exhibited prolonged activation of p38 and JNK, but not of ERK, following exposure to either peptidoglycan or lipoteichoic acid. Compared with wild-type (WT) macrophages, Mkp-1(-/-) macrophages produced more proinflammatory cytokines such as TNF-alpha and IL-6. Moreover, after challenge with peptidoglycan, lipoteichoic acid, live or heat-killed Staphylococcus aureus bacteria, Mkp-1 KO mice also mounted a more robust production of cytokines and chemokines, including TNF-alpha, IL-6, IL-10, and MIP-1alpha, than did WT mice. Accordingly, Mkp-1 KO mice also exhibited greater NO production, more robust neutrophil infiltration, and more severe organ damage than did WT mice. Surprisingly, WT and Mkp-1 KO mice exhibited no significant difference in either bacterial load or survival rates when infected with live S. aureus. However, in response to challenge with heat-killed S. aureus, Mkp-1 KO mice exhibited a substantially higher mortality rate compared with WT mice. Our studies indicate that MKP-1 plays a critical role in the inflammatory response to Gram-positive bacterial infection. MKP-1 serves to limit the inflammatory reaction by inactivating JNK and p38, thus preventing multiorgan failure caused by exaggerated inflammatory responses.

Levosimendan restores both systolic and diastolic cardiac performance in lipopolysaccharide-treated rabbits: Comparison with dobutamine and milrinone

OBJECTIVE

Current treatment strategies for severe septic conditions (i.e., intravenous fluids, vasopressors, and cardiac inotropes) reestablish fluid balance and improve cardiac systole but do not address diastolic dysfunction. Our study aimed to fully characterize both systolic and diastolic abnormalities of sepsis-associated heart failure and to identify treatment that would support full-cycle cardiac improvement.

DESIGN

Endotoxin-injected rabbits, an animal model of abnormal cardiac function in human sepsis, were used to delineate cardiac abnormalities and to examine effects of drug treatments on heart systolic and diastolic function (n = 30); saline-injected animals served as comparators (n = 17). As treatment, three inotropes commonly used for treatment of cardiac failure were infused for 45 mins in separate animal groups-milrinone, dobutamine, and levosimendan.

MEASUREMENTS

Variables of left ventricular systolic and diastolic function were assessed with a pressure conductance catheter. Measurements were made before and after endotoxin/saline injection and before and after inotrope treatment.

RESULTS

Pressure-volume analyses of the left ventricle showed marked impairment in systolic function and in all indices of diastolic function (isovolumic relaxation time constant, left ventricular end-diastolic pressure, and end-diastolic pressure-volume relationship) in endotoxin-treated rabbits. The inotropes, milrinone, dobutamine, and levosimendan, could each partially or completely restore systolic function in the lipopolysaccharide-treated rabbits. However, only levosimendan therapy led to additional beneficial effects on left ventricular relaxation and diastolic function.

CONCLUSIONS

Cardiac failure in severe sepsis results from impairments in both systolic and diastolic functions. Treatment with the calcium sensitizer levosimendan improved both systolic and diastolic cardiac functions in septic animals, but cyclic adenosine monophosphate-dependent inotropes milrinone and dobutamine only improved systolic function.

Interdépendance cœur–poumons chez le patient ventilé par pression positive

Heart-lung interactions during positive-pressure ventilation are characterized by an extreme sensibility to the patient's intravascular volume status. Indeed, a fall in cardiac output due to decreased ventricular preload can be observed when initiating positive-pressure ventilation. This phenomenon is due to the close anatomic-functional association between heart and lungs, and to the fact that pulmonary volume and intrathoracic pressure variations cyclically modify heart-lung interactions. The present review address the questions of the physiological and physiopathological effects of positive-pressure ventilation on the right and left venous returns, and on pulmonary and systemic vascular resistances.

Use of N-terminal pro-brain natriuretic peptide to detect acute cardiac dysfunction during weaning failure in difficult-to-wean patients with chronic obstructive pulmonary disease

OBJECTIVE

To evaluate the utility of serial measurements of plasma N-terminal pro-brain natriuretic peptide (NT-proBNP) to detect acute cardiac dysfunction during weaning failure in difficult to wean patients with chronic obstructive pulmonary disease.

DESIGN

Prospective observational cohort study.

SETTING

A 14-bed general intensive care unit in a university hospital.

PATIENTS

Nineteen patients mechanically ventilated for chronic obstructive pulmonary disease exacerbation who were difficult to wean.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Cardiac and hemodynamic variables, arterial and central venous blood gas, breathing pattern, respiratory mechanics, indexes of oxygen cost of breathing, and plasma levels of NT-proBNP were measured and analyzed immediately before (baseline) and at the end of a spontaneous breathing trial. Eight of 19 patients (42%) were identified with acute cardiac dysfunction at the end of the weaning trial. Baseline NT-proBNP levels were significantly higher (median 5000, interquartile range 4218 pg/mL) in these patients than in patients without evidence of acute cardiac dysfunction (median 1705, interquartile range 3491 pg/mL). Plasma levels of NT-proBNP increased significantly at the end of the spontaneous breathing trial only in patients with acute cardiac dysfunction (median 12,733, interquartile range 16,456 pg/mL, p < .05). The elevation in NT-proBNP at the end of the weaning trial had a good diagnostic performance in detecting acute cardiac dysfunction, as estimated by area under the receiver operating characteristic curve analysis (area under the curve 0.909, se 0.077, 95% confidence interval 0.69-0.98; p < .0001, cutoff = 184.7 pg/mL).

CONCLUSIONS

Serial measurements of NT-proBNP plasma levels provided a noninvasive manner to detect acute cardiac dysfunction during an unsuccessful weaning trial in difficult to wean patients with chronic obstructive pulmonary disease. The utility of this test as a complement of the standard clinical monitoring of the weaning trial deserves further investigation.

Extravascular lung water measurements and hemodynamic monitoring in the critically ill: bedside alternatives to the pulmonary artery catheter

The recently completed Fluid and Catheter Treatment Trial conducted by the National Institutes of Health ARDSNetwork casts doubt on the value of routine pulmonary artery catheterization for hemodynamic management of the critically ill. Several alternatives are available, and, in this review, we evaluate the theoretical, validation, and empirical databases for two of these: transpulmonary thermodilution measurements (yielding estimates of cardiac output, intrathoracic blood volume, and extravascular lung water) that do not require a pulmonary artery catheter, and hemodynamic measurements (including estimates of cardiac output and ejection time, a variable sensitive to intravascular volume) obtained by esophageal Doppler analysis of blood flow through the descending aorta. We conclude that both deserve serious consideration as a means of acquiring useful hemodynamic data for managing shock and fluid resuscitation in the critically ill, especially in those with acute lung injury and pulmonary edema, but that additional study, including carefully performed, prospective clinical trials demonstrating outcome benefit, is needed.

Management of sepsis during the early "golden hours"

Severe sepsis and septic shock are common causes of morbidity and mortality. Interventions directed at specific endpoints, when initiated early in the "golden hours" of patient arrival at the hospital, seem to be promising. Early hemodynamic optimization, administration of appropriate antimicrobial therapy, and effective source control of infection are the cornerstones of successful management. In patients with vasopressor-dependent septic shock, provision of physiologic doses of replacement steroids may result in improved survival. Administration of drotrecogin alfa (activated), (activated protein C) has been shown to improve survival in patients with severe sepsis and septic shock who have a high risk of mortality. In this article we review the multi-modality approach to early diagnosis and intervention in the therapy of patients with severe sepsis and septic shock.

Bedside echocardiographic evaluation of hemodynamics in sepsis: is a qualitative evaluation sufficient?

OBJECTIVE

Transesophageal echocardiography (TEE) has proven its efficiency in assessing hemodynamics in patients by its ability to evaluate cardiac function and fluid responsiveness. Classically, it requires quantitative measurements, whereas in routine practice TEE is used in our unit especially as a qualitative procedure. We assessed the accuracy of this qualitative central hemodynamic evaluation obtained by TEE at the bedside.

DESIGN AND SETTING

Prospective study conducted in a medical ICU between September 2004 and April 2005. All TEE examinations performed in consecutive patients hospitalized for septic shock and mechanically ventilated for an associated acute lung injury were eligible for evaluation. Intensivists trained in echocardiography were asked to classify (a) respiratory changes in the superior vena cava (SVC), (b) left ventricular (LV) systolic function, (c) right ventricular (RV) end-diastolic size, and (d) shape and kinetics of the interventricular septum (IVS). A post-hoc quantitative evaluation was then performed by a trained investigator unaware of the patients' status.

RESULTS

We evaluated 83 examinations in 30 patients. Qualitative evaluation was easily able to distinguish patients with significant or nonsignificant SVC respiratory changes, normal, moderately or markedly depressed LV systolic function, and nondilated or dilated right ventricle. Acute cor pulmonale was also well recognized.

CONCLUSION

By its ability accurately to evaluate hemodynamic status qualitative TEE could be useful for intensivists in managing circulatory failure in septic shock, rendering the more time-consuming quantitative evaluation useless.

Echocardiographic measurement of fluid responsiveness

PURPOSE OF REVIEW

Fluid responsiveness is a relatively new concept. It enables the efficacy of volume expansion to be predicted before use, rather than assessed afterwards, thus avoiding inappropriate fluid infusion. Echocardiography is a fantastic noninvasive tool which can directly visualize the heart and assess cardiac function. Its use was long limited by the absence of accurate indices to diagnose hypovolemia and predict the effect of volume expansion. In the last few years, several French teams have used echocardiography to develop new parameters of fluid responsiveness, taking advantage of its ability to monitor cardiac function beat by beat during the respiratory cycle.

RECENT FINDINGS

In mechanically ventilated patients perfectly adapted to the respirator, respiratory variations in superior and inferior vena cava diameters and in left ventricular stroke volume have been validated as parameters of fluid responsiveness. In our opinion, the collapsibility index of the superior vena cava is the most reliable of these parameters, but does require transesophageal echocardiography.

SUMMARY

Echocardiography has been widely demonstrated to predict fluid responsiveness accurately. This is now a complete and noninvasive tool able to accurately determine hemodynamic status in circulatory failure.

Preprotachykinin-A Gene Products Are Key Mediators of Lung Injury in Polymicrobial Sepsis

Preprotachykinin-A (PPT-A) gene products substance P and neurokinin-A have been shown to play an important role in neurogenic inflammation. To investigate the role of PPT-A gene products in lung injury in sepsis, polymicrobial sepsis was induced by cecal ligation and puncture in PPT-A gene-deficient mice (PPT-A(-/-)) and the wild-type control mice (PPT-A(+/+)). PPT-A gene deletion significantly protected against mortality, delayed the onset of lethality, and improved the long-term survival following cecal ligation and puncture-induced sepsis. PPT-A(-/-) mice also had significantly attenuated inflammation and damage in the lungs. The data suggest that deletion of the PPT-A gene may have contributed to the disruption in recruitment of inflammatory cells resulting in protection against tissue damage, as in these mice the sepsis-associated increase in chemokine levels is significantly attenuated.

Organ dysfunction during sepsis

BACKGROUND

Multiple organ dysfunction syndrome is the commonest reason for sepsis-associated mortality.

DISCUSSION

In the 40 years since it was first described understanding of its pathophysiology has improved, and novel methodologies for monitoring and severity of illness scoring have emerged. These, together with the development of systematic strategies for managing organ dysfunction in sepsis, and potentially effective new therapeutic interventions, should assist in reducing sepsis-associated mortality.

CONCLUSION

These historical developments are discussed, and the reader is directed to these references for further guidance.

Hydrocortisone increases the sensitivity to α1-adrenoceptor stimulation in humans following hemorrhagic shock*

OBJECTIVE

To assess the pressor response to phenylephrine infusion before and after hydrocortisone in severe trauma patients and to correlate this response with their adrenal reserve.

DESIGN

Prospective clinical study.

SETTING

Surgical intensive care unit in a university teaching hospital.

PATIENTS

Twenty-three young trauma patients (Injury Severity Score, 38 +/- 14) were studied at the end of the resuscitative period (27 +/- 15 hrs after trauma).

INTERVENTIONS

Total cortisol response to intravenous corticotropin bolus (250 microg) was obtained. Total cortisol response <9 microg/dL defined an impaired adrenal function and the patient was called a nonresponder. Twelve to 24 hrs following this stimulation, phenylephrine was infused in a stepwise manner to establish the phenylephrine-mean arterial pressure dose-response curve before and after intravenous hydrocortisone administration (50 mg). An Emax model was used to describe the curve; the influence of the group (responder/nonresponder), the sequence (before/after hydrocortisone), and three covariates (Injury Severity Score, shock, and interleukin-6) were thereafter tested.

MEASUREMENTS AND MAIN RESULTS

Forty-three percent of patients were nonresponders. Total cortisol response was not correlated with serum albumin concentration and was negatively correlated with the interleukin-6 concentration. A trend for a higher incidence of nonresponders (53% vs. 36%) and a lesser total cortisol response (7.9 +/- 5.1 vs. 12.5 +/- 5.1 microg/dL) was observed in the shock patients. A phenylephrine dose-response structure (E0, ED50, and Emax) was described without influence of the group and the sequence. However, hydrocortisone induced a 37% decrease in ED50 without change in Emax in the shock patients.

CONCLUSION

An acute administration of hydrocortisone increases the sensitivity to alpha1-adrenoceptor stimulation in fully resuscitated severe trauma patients following hemorrhagic shock. This effect is independent of the adrenal reserve of the patients and different from that previously reported in septic patients.

Echocardiography in the critically ill: current and potential roles

BACKGROUND

The use of echocardiography in the critically ill presents specific challenges. However, information of direct relevance to clinical management can be obtained relating to abnormalities of structure and function and can be used to estimate pulmonary arterial and venous pressures.

DISCUSSION

Investigation of the consequences of myocardial ischaemia, valvular dysfunction and pericardial disease can be facilitated, and changes characteristic of specific conditions (e.g. sepsis, pulmonary thromboembolism) detected. Echocardiography can also be used to monitor the effects of therapeutic interventions.

CONCLUSIONS

The applications of echocardiography in the critical care setting (excluding standard peri-operative echocardiography for cardiac surgery) are reviewed, with particular emphasis on the assessment of cardiac physiology.

Early veno-venous haemodiafiltration for sepsis-related multiple organ failure

Introduction

We conducted a prospective observational study from January 1995 to December 2004 to evaluate the impact on recovery of a major advance in renal replacement therapy, namely continuous veno-venous haemodiafiltration (CVVHDF), in patients with refractory septic shock.

Method

CVVHDF was implemented after 6–12 hours of maximal haemodynamic support, and base excess monitoring was used to evaluate the improvement achieved. Of the 60 patients studied, 40 had improved metabolic acidosis after 12 hours of CVVHDF, with a progressive improvement in all failing organs; the final mortality rate in this subgroup was 30%. In contrast, metabolic acidosis did not improve in the remaining 20 patients after 12 hours of CVVHDF, and the mortality rate in this subgroup was 100%. The crude mortality rate for the whole group was 53%, which is significantly lower than the predicted mortality using Simplified Acute Physiology Score II (79%).

Conclusion

Early CVVHDF may improve the prognosis of sepsis-related multiple organ failure. Failure to correct metabolic acidosis rapidly during the procedure was a strong predictor of mortality.

The acutely decompensated right ventricle: pathways for diagnosis and management

Decompensated right ventricular (RV) failure is becoming increasingly common as the prevalence of predisposing conditions grows. Advances in diagnosis and management have granted insights into the following pathophysiologic mechanisms of RV dysfunction: impaired RV contractility, RV pressure overload, and RV volume overload. Emerging imaging modalities, such as cardiac MRI, and new therapeutic agents, such as pulmonary selective vasodilators, have expanded our options for evaluation and management, respectively. An improved understanding of pathophysiology and technologic progress provides us with new pathways in the diagnosis and hemodynamic support of these often critically ill patients.

Pre-ejection period variations predict the fluid responsiveness of septic ventilated patients

OBJECTIVES

In septic patients with acute circulatory failure, reliable predictors of fluid responsiveness are needed at the bedside. We hypothesized that the respiratory change in pre-ejection period (DeltaPEP) would allow the prediction of changes in cardiac index following volume administration in mechanically ventilated septic patients.

DESIGN

Prospective clinical investigation.

SETTING

A ten-bed hospital intensive care unit.

PATIENTS

Patients admitted after septic shock equipped with an arterial catheter.

INTERVENTIONS

Pre-ejection period (PEP)--defined as the time interval between the beginning of the R wave on the electrocardiogram and the upstroke of the radial arterial pressure curve (PEPKT) or the pulse plethysmographic waveforms (PEPPLET)--and cardiac index (transthoracic echocardiography-Doppler) were determined before and after volume infusion of colloid (8 mL x kg). DeltaPEP (%) was defined as the difference between expiratory and inspiratory PEP divided by the mean of expiratory and inspiratory values. Respiratory changes in pulse pressure (DeltaPP) was also measured.

MEASUREMENTS AND MAIN RESULTS

: Twenty-two volume challenges were done in 20 deeply sedated patients. DeltaPEPKT, DeltaPEPPLET, and DeltaPP (measured in all patients) before volume expansion were correlated with cardiac index change after fluid challenge (r = .73, r = .67, and r = .70, respectively, p < .0001). Patients with a cardiac index increase induced by volume expansion > or = 15% and <15% were classified as responders and nonresponders, respectively. Receiver operating characteristic curves showed that the threshold DeltaPP value of 17% allowed discrimination between responder/nonresponder patients with a sensitivity of 85% and a specificity of 100%. For both DeltaPEPKT and DeltaPEPPLET, the best threshold value was 4% with a sensitivity-specificity of 92%-89% and 100%-67%, respectively.

CONCLUSIONS

The present study found DeltaPEPKT and DeltaPEPPLET to be as accurate as DeltaPP in the prediction of fluid responsiveness in mechanically ventilated septic patients.

Monitoring of right-sided heart function

PURPOSE OF REVIEW

Because the right side of the heart supplies blood to the pulmonary circulation, its integrity is required for both adequate respiratory and circulatory function. By reducing pulmonary perfusion, right-sided heart failure may compromise arterial oxygenation and left ventricular filling, and monitoring of right-sided heart function at the bedside in critically ill patients is fundamental. Two recent clinical commentaries have focused on the invaluable help provided by echocardiography for this purpose.

RECENT FINDINGS

Bedside echocardiography has supplanted invasive procedures as the best tool to evaluate right-sided heart function. Although not recent, this technique, previously reserved for cardiologists, has recently gained a larger acceptance in respiratory intensive care units. Echocardiographic examination detects excessive right ventricular afterload, visualized by septal dyskinesia, and its usual consequence, right ventricular enlargement, which impairs left ventricular filling.

SUMMARY

Monitoring of right-sided heart function is essential in a clinical setting associated with hemodynamic instability, such as severe sepsis or acute coronary artery obstruction, and also in that it is associated with increased pulmonary vascular resistance, as in massive pulmonary embolism or acute respiratory failure. Moreover, use of mechanical ventilation requires regular evaluation of its effects on the right side of the heart.

Incidence, causes and prognosis of hypotension related to meprobamate poisoning

OBJECTIVE

Meprobamate self-poisoning has been reported as potentially inducing hypotension. We examined the incidence and causes of hypotension induced by this poisoning and its prognosis.

DESIGN AND SETTING

Retrospective observational study conducted in a medical ICU between June 1997 and October 2003. Seventy-four patients admitted for meprobamate poisoning and needing mechanical ventilation were included. Demographic, clinical, and laboratory data were compared between patients with and without hypotension. All echocardiograms recorded in patients with hypotension were reviewed, and left ventricular (LV) and right ventricular (RV) functions were assessed.

RESULTS

Twenty-nine (40%) patients exhibited hypotension without any significant difference in age, gender, cardiac history, or meprobamate concentration in blood when compared to patients without hypotension. Base excess was significantly lower in patients with hypotension. Echocardiography demonstrated a hypokinetic state, associating decreased LV ejection fraction (45+/-15%) and cardiac index (2+/-0.7 l min(-1) m(-2)), and increased inferior vena cava diameter. Most patients with hypotension received inotropic drugs by infusion, and were ventilated for significantly longer.

CONCLUSIONS

Meprobamate self-poisoning induces hypotension, notably related to cardiac failure, in about 40% of cases. This has important therapeutic consequences, as frequent inotropic drug infusion. The mechanisms of cardiac toxicity remain largely unknown, and no predictive factor could be isolated.

Bedside ultrasonography in the ICU: part 1

Ultrasonography has become an invaluable tool in the management of critically ill patients. Its safety and portability allow for use at the bedside to provide rapid, detailed information regarding the cardiovascular system and the function and anatomy of certain internal organs. Echocardiography can noninvasively elucidate cardiac function and structure. This information is vital in the management hemodynamically unstable patients in the ICU. In addition, ultrasonography has particular value for the assessment and safe drainage of pleural and intra-abdominal fluid and the placement of central venous catheters. A new generation of portable, battery-powered, inexpensive, hand-carried ultrasound devices have recently become available; these devices can provide immediate diagnostic information not assessable by physical examination alone and allow for ultrasound-guided thoracocentesis, paracentesis, and central venous cannulation. This two-part article reviews the application of bedside ultrasonography in the ICU.

NH2 terminal pro–brain natriuretic peptide plasma level as an early marker of prognosis and cardiac dysfunction in septic shock patients*

OBJECTIVE

To investigate N-terminal pro-brain natriuretic peptide (NT-proBNP) level as a prognostic factor and a marker of myocardial dysfunction in patients with septic shock.

DESIGN

Prospective observational study.

SETTING

Intensive care unit.

SUBJECTS

A total of 39 patients diagnosed with septic shock and requiring mechanical ventilation.

MEASUREMENTS AND MAIN RESULTS

Demographic, hemodynamic, respiratory, and biological data (notably NT-proBNP, lactate, and cardiac troponin I) were collected at inclusion and every 12 hrs. The independent factors for death were higher Sequential Organ Failure Assessment score in the 24-hr period after inclusion (odds ratio, 4.7; 95% confidence interval, 1.15-19.3) and the highest NT-proBNP level in the 24-hr period after inclusion (odds ratio, 1.12 per 1000 pg/mL increase; 95% confidence interval, 1.05-1.26). An NT-proBNP of >13,600 pg/mL predicted intensive care unit mortality with an accuracy of 77%. Area under the receiver operating characteristic curve was 0.8 (p = .002; 95% confidence interval, 0.66-0.93). NT-proBNP levels were over the accepted normal range in all patients. Values were highest between 24 and 36 hrs after onset of septic shock and were significantly higher in nonsurvivors at each time between inclusion and day 7. The lowest left ventricular stroke work index of the first 24-hr period after inclusion was the only factor that independently influenced higher NT-proBNP levels at the same time (odds ratio, 0.91; 95% confidence interval, 0.84-0.98).

CONCLUSION

NT-proBNP seems to be an early factor of prognosis and myocardial dysfunction in patients with septic shock.

Septic shock

Septic shock, the most severe complication of sepsis, is a deadly disease. In recent years, exciting advances have been made in the understanding of its pathophysiology and treatment. Pathogens, via their microbial-associated molecular patterns, trigger sequential intracellular events in immune cells, epithelium, endothelium, and the neuroendocrine system. Proinflammatory mediators that contribute to eradication of invading microorganisms are produced, and anti-inflammatory mediators control this response. The inflammatory response leads to damage to host tissue, and the anti-inflammatory response causes leucocyte reprogramming and changes in immune status. The time-window for interventions is short, and treatment must promptly control the source of infection and restore haemodynamic homoeostasis. Further research is needed to establish which fluids and vasopressors are best. Some patients with septic shock might benefit from drugs such as corticosteroids or activated protein C. Other therapeutic strategies are under investigation, including those that target late proinflammatory mediators, endothelium, or the neuroendocrine system.

Methods of monitoring shock

Intensive monitoring is a crucial component of the management of shock. However, there is little consensus about optimal strategies for monitoring. Although the pulmonary artery catheter has been widely used, conflicting data exist about the utility of this device. A variety of other techniques have been developed in hopes of providing clinically useful information about myocardial function, intravascular volume, and indices of organ function. In addition, there is evolving evidence that targeting and monitoring certain physiological goals may be most important early in the course of shock. In this chapter, we examine many of the available monitoring techniques and the evidence supporting their use.

The function of mitogen-activated protein kinase phosphatase-1 in peptidoglycan-stimulated macrophages

Mitogen-activated protein (MAP) kinases play a pivotal role in the macrophages in the production of proinflammatory cytokines triggered by lipopolysaccharides. However, their function in the responses of macrophages to Gram-positive bacteria is poorly understood. Even less is known about the attenuation of MAP kinase signaling in macrophages exposed to Gram-positive bacteria. In the present study, we have investigated the regulation of MAP kinases and the role of MAP kinase phosphatase (MKP)-1 in the production of pro-inflammatory cytokines using murine RAW264.7 and primary peritoneal macrophages after peptidoglycan stimulation. Treatment of macrophages with peptidoglycan resulted in a transient activation of JNK, p38, and extracellular signal-regulated kinase. Most interestingly, MKP-1 expression was potently induced by peptidoglycan, and this induction was concurrent with MAP kinase dephosphorylation. Triptolide, a diterpenoid triepoxide, potently blocked the induction of MKP-1 by peptidoglycan and prolonged the activation of JNK and p38. Overexpression of MKP-1 substantially attenuated the production of tumor necrosis factor (TNF)-alpha induced by peptidoglycan, whereas knockdown of MKP-1 by small interfering RNA substantially increased the production of both TNF-alpha and interleukin-1 beta. Finally, we found that in primary murine peritoneal macrophages, MKP-1 induction following peptidoglycan stimulation also coincided with inactivation of JNK and p38. Blockade of MKP-1 induction resulted in a sustained activation of both JNK and p38 in primary macrophages. Our results reveal that MKP-1 critically regulates the expression of TNF-alpha and interleukin-1 beta in RAW264.7 cells and further suggest a central role for this phosphatase in controlling the inflammatory responses of primary macrophages to Gram-positive bacterial infection.

Superior vena caval collapsibility as a gauge of volume status in ventilated septic patients

OBJECTIVE

In mechanically ventilated patients inspiratory increase in pleural pressure during lung inflation may produce complete or partial collapse of the superior vena cava. Occurrence of this collapse suggests that at this time external pressure exerted by the thoracic cavity on the superior vena cava is greater than the venous pressure required to maintain the vessel fully open. We tested the hypothesis that measurement of superior vena caval collapsibility would reveal the need for volume expansion in a given septic patient.

DESIGN AND SETTING

Prospective data collection for 66 successive patients in septic shock admitted in a medical intensive care unit and mechanically ventilated for an associated acute lung injury.

MEASUREMENTS AND RESULTS

We simultaneously measured superior vena caval collapsibility by echocardiography and cardiac index by the Doppler technique at baseline and after a 10 ml/kg volume expansion by 6% hydroxyethyl starch in 30 min. The threshold superior vena caval collapsibility of 36%, calculated as (maximum diameter on expiration-minimum diameter on inspiration)/maximum diameter on expiration, allowed discrimination between responders (defined by an increase in cardiac index of at least 11% induced by volume expansion) and nonresponders, with a sensitivity of 90% and a specificity of 100%.

CONCLUSIONS

Superior vena cava measurement should be systematically performed during routine echocardiography in septic shock as it gives an accurate index of fluid responsiveness.

[Physiopathology of severe sepsis]

Regarding the definition. Severe sepsis associates an explosive inflammatory reaction and organ failure. It is secondary to bacterial, fungal or viral infection. It can be at the origin of acute circulatory failure (state of septic shock). Response of the organism to infection. The presence of certain components of the membrane of pathogenic agents induces the release of various mediators in cascade, notably cytokines. Toll-like receptors (10 cloned in humans) intervene in the detection of microbes and in the inherent and subsequently adaptive immune response. Immune paralysis. The release of pro-inflammatory mediators characterizes the initial phase of sepsis. Persistence of the latter provokes acquired immunodepression, related to an anti-inflammatory profile, and hence to a delayed decrease in hypersensitivity, an incapacity to cope with the infection and the onset of nosocomial infections. The role of the mediators. During sepsis, the cytokines are predominantly pro-inflammatory (TNF-alpha and notably IL-1beta) whereas others, produced concomitantly or subsequently, are predominantly anti-inflammatory (IL-10 in particular). In fact, the majority of the cytokines have multiple and intrinsic effects, they mediate immune defense but also pathological manifestations. Many other mediators intervene: coagulation or complement systems, contact system, breakdown products of the phospholipid membrane, arachidonic acid metabolites, free radicals and nitrous oxide. Endocrine and metabolic dysregulations. The concept of relative adrenal insufficiency and peripheral syndrome of resistance to glycocorticosteroids have led to hormone replacement therapy during septic shock. Acute insulin resistance has also been described. The role of the endothelium and coagulation. The endothelium plays a key part in the onset of vascular insufficiency during sepsis due to abnormalities in vasomotricity and thrombomodulation. The anticoagulant regulating system is perturbed; there is a decrease in protein C with inactivation of its active form, which has pro-fibrinolytic properties, and a decrease in antithrombin III. Regarding myocardial dysfunction During septic shock there is often severe left ventricular systolic dysfunction, sometimes also involving the right ventricle, largely under-diagnosed despite its severe prognosis, and associated with reduced or even collapsed heart rate.

[Treatment of severe sepsis and septic shock]

The 3 poles of treatment. These are the hemodynamic management, early antibiotherapy and more specific treatments, based on improved physiopathological knowledge. From a hemodynamic point of view The first stage must always be to detect and correct the hypovolemia. The administration of vasopressive amines (or vasoconstricting amines) is mandatory in the case of septic shock. The choice of the antibiotics In the absence of microbiological proof, it is based on the germs most often encountered in infections of the suspected site and community or nosocomial nature of the infection. The antibiotherapy must be set-up as early as possible once the bacteriological samples have been. Treatments based on the physiopathology The activated protein C possesses pro-fibrinolytic, anticoagulant and anti-inflammatory properties; it obtained marketing Authorization in Europe for patients with severe sepsis and at least 2 organ failures or hypotension. Low-dose corticosteroids should be prescribed in the case of septic shock with prolonged use of catecholamines, and if possible following a test with Synacthène(R) (relative adrenal insufficiency). Intensive insulin therapy is aimed at maintaining normal glycemia in the patients for as long as possible.