Relative adrenal insufficiency as a predictor of disease severity, mortality, and beneficial effects of corticosteroid treatment in septic shock

OBJECTIVE

To evaluate the concept of relative adrenal insufficiency necessitating corticosteroid therapy in septic shock.

DESIGN

Retrospective study.

SETTING

Medical-surgical intensive care unit of a university hospital.

PATIENTS

We studied 218 consecutive patients with septic shock in a 3-yr period who underwent a short 250-microg adrenocorticotropic hormone test because of >6 hrs of hypotension requiring repeated fluid challenges and/or vasopressor/inotropic treatment.

INTERVENTIONS

The test was performed by intravenously injecting 250 mug of synthetic adrenocorticotropic hormone and measuring cortisol immediately before and 30 and 60 mins postinjection.

MEASUREMENTS AND MAIN RESULTS

Intensive care unit mortality until day 28 was 22%. Nonsurvivors had greater disease severity, as exemplified by higher Simplified Acute Physiology Score II and Sequential Organ Failure Assessment score, on the day of adrenocorticotropic hormone testing. Cortisol levels directly correlated with albumin levels. Simplified Acute Physiology Score II and Sequential Organ Failure Assessment score increased with higher strata of baseline cortisol/albumin or lower cortisol increases/albumin ratios as measures of free cortisol. Baseline cortisol, cortisol increases, and albumin levels did not independently contribute to mortality prediction by disease severity and absence of corticosteroid (hydrocortisone) treatment in a Cox proportional hazard model, although adrenocorticotropic hormone-induced cortisol increase <100 nmol/L (n = 53) predicted mortality (p = .007). Posttest treatment by corticosteroids (n = 161, 74%) was associated with higher survival in patients with cortisol increase <100 nmol/L (p = .0296).

CONCLUSIONS

In intensive care unit patients with septic shock, the cortisol response to adrenocorticotropic hormone inversely relates to disease severity, independent of blood cortisol binding. An adrenocorticotropic hormone-induced cortisol increase <100 nmol/L predicts mortality and beneficial effects of corticosteroid treatment. The data favor relative adrenal insufficiency.

Coronary stent occlusion after platelet transfusion: a case series

Early stent occlusion after myocardial infarction is associated with increased morbidity and mortality, and antiplatelet drugs are applied to prevent these complications. We report on 3 patients with gastrointestinal bleeding or who were scheduled for emergency surgery and who received donor platelet transfusion early in the course after stenting. These patients had symptomatic coronary artery stenoses and were treated with antiplatelet therapy. Stent occlusion was diagnosed 6 to 17 hours after donor platelet transfusion, suggested by electrocardiographic and, in 1 patient, angiographic findings. One patient died of intractable bleeding from the gastrointestinal tract. Our observations emphasize the risks involved in platelet transfusion, and support withholding such therapy, unless vitally indicated, in patients who have undergone recent bare-metal coronary artery stent implantation.

Cardiac Output Measured by a New Arterial Pressure Waveform Analysis Method Without Calibration Compared With Thermodilution After Cardiac Surgery

OBJECTIVES

To investigate whether measuring cardiac output and its course after cardiac surgery by a new analysis technique of radial artery pressure waves, without need for calibration (FloTrac/Vigileo [FV]; Edwards Lifesciences, Irvine, CA), conforms to the standard bolus thermodilution method via a pulmonary artery catheter (PAC).

DESIGN

Prospective study.

SETTING

Intensive care unit of university hospital.

PARTICIPANTS

Twenty patients for up to 24 hours after cardiac surgery.

INTERVENTIONS

Simultaneous and triplicate PAC thermodilution and FV cardiac output measurements at 1 and 3 hours after surgery and the following morning.

MEASUREMENTS AND MAIN RESULTS

Fifty-six simultaneous measurement sets were obtained. Mean cardiac output (PAC) ranged between 2.8 and 10.3 L/min and for the FV method between 3.3 and 8.8 L/min. The coefficient of variation for pooled measurements was 7.3% for the PAC and 3.0% for the FV method. For pooled data, the r2 was 0.55 (p < 0.001), with a bias of -0.14, precision of 1.00 L/min, and 95% limits of agreement between -2.14 and 1.87 L/min in a Bland-Altman plot. Also, the FV method tended to overestimate cardiac output when <7 L/min and increased with time, whereas mean arterial pressure increased and PAC cardiac output did not change. Changes in cardiac output correlated (r2 = 0.52, p < 0.001).

CONCLUSIONS

The FV arterial pressure waveform analysis method is a clinically applicable method for cardiac output assessment without calibration, after cardiac surgery. It performs well at low cardiac outputs but remains sensitive to changes in vascular tone.

Epidemiology of acute lung injury and acute respiratory distress syndrome in The Netherlands: A survey

BACKGROUND

The characteristics, incidence and risk factors for acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) may depend on definitions and geography.

METHODS

A prospective, 3-day point-prevalence study was performed by a survey of all intensive care units (ICU) in the Netherlands (n=96). Thirty-six ICU's responded (37%), reporting on 266 patients, of whom 151 were mechanically ventilated. The questionnaire included criteria and potential risk factors for ALI/ARDS, according to the North American-European Consensus Conference (NAECC) or the lung injury score (LIS>or=2.5).

RESULTS

Agreement between definitions was fair (kappa 0.31-0.42, P=0.001). ALI/ARDS was characterized, regardless of definition, by radiographic densities, low oxygenation ratios, high inspiratory O(2) and airway pressure requirements. Depending on definitions, ALI and ARDS accounted for about 12-33% and 7-9% of ICU admissions per year, respectively, constituting 21-58% (ALI) and 13-16% (ARDS) of all mechanically ventilated patients. The annual incidences of ALI and ARDS are 29.3 (95%CI 18.4-40.1) and 24.0 (95%CI 14.2-33.8) by NAECC, respectively, and are, respectively, 83.6 (95%CI 65.3-101.9) and 20.9 (95%CI 11.7-30.1) by LIS per 100,000. Risk factors for ALI/ARDS were aspiration, pneumonia, sepsis and chronic alcohol abuse (the latter only by NAECC).

CONCLUSION

The effect of definitions of ALI/ARDS on mechanical ventilation in the Netherlands is small. Nevertheless, the incidence of ALI/ARDS may be higher than in other European countries but lower than in the USA, and the incidence of ALI by LIS may overestimate compared to that by NAECC. Aspiration, pneumonia, sepsis and chronic alcohol abuse are major risk factors, largely independent of definitions.

Management of invasive pulmonary aspergillosis in non-neutropenic critically ill patients

During recent years, a rising incidence of invasive pulmonary aspergillosis (IPA) in non-neutropenic critically ill patients has been reported. Critically ill patients are prone to develop disturbances in immunoregulation during their stay in the ICU, which render them more vulnerable for fungal infections. Risk factors such as chronic obstructive pulmonary disease (COPD), prolonged use of steroids, advanced liver disease, chronic renal replacement therapy, near-drowning and diabetes mellitus have been described. Diagnosis of IPA may be difficult and obtaining histo- or cytopathological demonstration of the fungus in order to meet the gold standard for IPA is not always feasible in these patients. Laboratory markers used as a non-invasive diagnostic tool, such as the galactomannan antigen test (GM), 1,3-beta-glucan, and Aspergillus PCR, show varying results. Antifungal therapy might be considered in patients with persistent pulmonary infection who exhibit risk factors together with positive cultures or sequentially positive GM and Aspergillus PCR in serum, in whom voriconazole is the drug of choice. The benefit of combination antifungal therapy lacks sufficient evidence so far, but this treatment might be considered in patients with breakthrough infections or refractory disease.

Quantitative detection of Staphylococcus aureus and Enterococcus faecalis DNA in blood to diagnose bacteremia in patients in the intensive care unit

Direct detection of bacterial DNA in blood offers a fast alternative to blood culture and is presumably unaffected by the prior use of antibiotics. We evaluated the performance of two real-time PCR assays for the quantitative detection of Staphylococcus aureus bacteremia and for Enterococcus faecalis bacteremia directly in blood samples, without prior cultivation. Whole-blood samples for PCR were obtained simultaneously with blood cultures from patients admitted to the intensive care unit of our hospital. After the extraction of DNA from 200 mul of blood, real-time PCR was performed for the specific detection and quantification of S. aureus and E. faecalis DNA. The sensitivity for bacteremia of the S. aureus PCR was 75% and that of the E. faecalis PCR was 73%, and both tests had high specificity values (93 and 96%, respectively). PCR amplification reactions were positive for S. aureus for 10 (7%) blood samples with negative blood cultures, and 7 (4%) PCR reactions were positive for E. faecalis. The majority of these PCR results were likely (50%) or possibly (42%) related to infection with the specific microorganism, based on clinical data and radiological and microbiological investigations. PCR results were concordant for 95% of paired whole-blood samples, and blood culture results were concordant for 97% of the paired samples. We conclude that the detection of S. aureus and E. faecalis DNA in blood by real-time PCR enables a rapid diagnosis of bacteremia and that a positive DNAemia is related to proven or possible infection with the specific microorganism in the majority of patients with negative blood cultures.

The role of heparin and allied compounds in the treatment of sepsis

The crosstalk between coagulation and inflammation and the propensity for microthromboembolic disease during sepsis calls for anticoagulant measures to prevent tissue hypoxygenation and to attenuate organ damage and dysfunction. Only one anticoagulant, recombinant human activated protein C (aPC, drotrecogin-alpha) has a proven survival benefit when used as an adjunctive therapy for human sepsis, partly because of its anti-inflammatory effect. However, heparin (-like compounds) may exert similar beneficial anti-inflammatory actions as aPC, in spite of the relatively narrow therapeutic window for anticoagulation. This narrative review is based on a Medline search of relevant basic and clinical studies published in English and discusses the potential role of heparin in modulating inflammatory responses in the treatment of animal models and human sepsis and its harmful sequelae. In any case, the results of a meta-analysis based on animal data suggest a potentially life-saving effect of heparin (-like compounds) in the treatment of sepsis. Therefore, a prospective randomized clinical trial is called upon to study effects in human sepsis.

Continuous venovenous hemofiltration with or without predilution regional citrate anticoagulation: a prospective study

BACKGROUND/AIMS

Continuous venovenous hemofiltration (CVVH) requires anticoagulation to prevent circuit clotting and its use is contraindicated in patients with high bleeding risk. The aim of this study was to compare CVVH with and without regional citrate anticoagulation (RCA) with respect to filter life, azotemic control and cost.

METHODS

This was a prospective sequential cohort study. The first cohort of patients with a high bleeding risk and acute renal failure was treated by anticoagulant-free predilution CVVH (n = 31). In the second cohort, CVVH was applied with RCA (n = 20).

RESULTS

The median filter life was 41 h (interquartile range 20-62) with RCA and 12 h (8-28) without RCA (p = 0.001). The azotemic control was better in the group with RCA. The hourly cost was comparable between the two groups.

CONCLUSION

Regional anticoagulation with citrate-based replacement solution improved filter life compared to anticoagulant-free predilution CVVH. This regimen appeared safe, feasible and without metabolic complications or increased costs.

Increased permeability-oedema and atelectasis in pulmonary dysfunction after trauma and surgery: a prospective cohort study

BACKGROUND

Trauma and surgery may be complicated by pulmonary dysfunction, acute lung injury (ALI) and acute respiratory distress syndrome (ARDS), but the mechanisms are incompletely understood.

METHODS

We evaluated lung capillary protein permeability non-invasively with help of the 67Ga-transferrin pulmonary leak index (PLI) technique and extravascular lung water (EVLW) by the transpulmonary thermal-dye dilution technique in consecutive, mechanically ventilated patients in the intensive care unit within 24 h of direct, blunt thoracic trauma (n = 5, 2 with ARDS), and within 12 h of indirect trauma by transhiatal oesophagectomy (n = 8), abdominal surgery for cancer (n = 6) and bone surgery (n = 4). We studied transfusion history, haemodynamics, oxygenation and mechanics of the lungs. The lung injury score (LIS, 0-4) was calculated. Plain radiography was also done to judge densities and atelectasis.

RESULTS

The PLI and EVLW were elevated above normal in 61 and 30% of patients, respectively, and the PLI directly related to the number of red cell concentrates given (rs = 0.69, P < 0.001), without group differences. Oxygenation, lung mechanics, radiographic densities and thus the LIS (1.0 [0.25-3.5]) did not relate to PLI and EVLW. However, groups differed in oxygenation and airway pressures and impaired oxygenation related to the number of radiographic quadrants with densities (rs = 0.55, P = 0.007). Thoracic trauma patients had a worse oxygenation requiring higher airway pressures and thus higher LIS than the other patient groups, unrelated to PLI and EVLW but attributable to a higher cardiac output and thereby venous admixture. Finally, patients with radiographic signs of atelectasis had more impaired oxygenation and more densities than those without.

CONCLUSION

The oxygenation defect and radiographic densities in mechanically ventilated patients with pulmonary dysfunction and ALI/ARDS after trauma and surgery are likely caused by atelectasis rather than by increased permeability-oedema related to red cell transfusion.

Transpulmonary dilution-derived extravascular lung water as a measure of lung edema

PURPOSE OF REVIEW

This review highlights current insights concerning the (measurement of) extravascular lung water as an index of pulmonary edema, by transpulmonary dilution techniques. The focus is on the applicability of the technique at the bedside in monitoring critically ill patients.

RECENT FINDINGS

Several (animal) studies have been performed to validate the technique by postmortem gravimetry in different conditions. Moreover, recent clinical data emphasize the utility of the thermodilution-derived extravascular lung water, its contribution to the clinical manifestations of acute lung injury/acute respiratory distress syndrome, its response to treatment aimed at edema prevention or resolution, and as a prognostic parameter.

SUMMARY

The thermodilution-derived extravascular lung water is a useful adjunct to assess lung vascular injury, cardiogenic edema and overhydration and to guide treatment in critically ill patients. The effects on morbidity and mortality of this approach need to be studied further.

Relative adrenal insufficiency: an identifiable entity in nonseptic critically ill patients?

OBJECTIVE

To determine whether relative adrenal insufficiency (RAI) can be identified in nonseptic hypotensive patients in the intensive care unit (ICU).

DESIGN

Retrospective study in a medical-surgical ICU of a university hospital.

PATIENTS

One hundred and seventy-two nonseptic ICU patients (51% after trauma or surgery), who underwent a short 250 microg ACTH test because of > 6 h hypotension or vasopressor/inotropic therapy.

MEASUREMENTS

On the test day, the Simplified Acute Physiology Score II (SAPS II) and Sequential Organ Failure Assessment (SOFA) score were calculated to estimate disease severity. The ICU mortality until day 28 was recorded. Best discriminative levels of baseline cortisol, increases and peaks were established using receiver operating characteristic curves. These and corticosteroid treatment (in n = 112, 65%), among other variables, were examined by multiple logistic regression and Cox proportional hazard regression analyses to find independent predictors of ICU mortality until day 28.

RESULTS

ICU mortality until day 28 was 23%. Nonsurvivors had higher SAPS II and SOFA scores. Baseline cortisol levels correlated directly with albumin levels and SAPS II. In the multivariate analyses, a cortisol baseline > 475 nmol/l and cortisol increase < 200 nmol/l predicted mortality, largely dependent on disease severity but independent of albumin levels. Corticosteroid (hydrocortisone) treatment was not associated with an improved outcome, regardless of the ACTH test results.

CONCLUSION

In nonseptic hypotensive ICU patients, a low cortisol/ACTH response and treatment with corticosteroids do not contribute to mortality prediction by severity of disease. The data thus argue against RAI identifiable by cortisol/ACTH testing and necessitating corticosteroid substitution treatment in these patients.

Digital image analysis of cytoskeletal F-actin disintegration in renal microvascular endothelium following ischemia/reperfusion

BACKGROUND

Damaged and/or dysfunctional microvascular endothelium has been implicated in the pathogenesis of ischemic acute renal failure (ARF). Rapidly occurring changes in the endothelial F-actin cytoskeleton as observed in vitro might be responsible, but have been proven difficult to measure accurately in situ. Therefore, the purpose of this study was to examine several methods of digital image analysis in order to quantify the alterations of endothelial F-actin after renal ischemia and reperfusion (I/R), and to relate these to deterioration of renal function.

METHODS

Frozen sections of Sham and I/R rat kidneys were fixed in 4% formaldehyde and stained with rhodamine-phalloïdin. Microvascular structures were captured using a 3i Marianastrade mark digital imaging fluorescence microscope workstation. Images were analyzed using 3i SlideBooktrade mark software, employing several masking techniques and line-scans.

RESULTS

Digital image analysis demonstrated a decrease in the mean intensity of rhodamine-phalloïdin fluorescence after I/R from 1030 +/- 187 to 735 +/- 121 a.u. (arbitrary units, mean +/- SD, n = 7). The number of F-actin fragments per pixel increased from (15.8 +/- 4.9) x 10(-5) to (20.7 +/- 3.5) x 10(-5) (n = 7), indicating cytoskeletal fragmentation. In addition, line-scan analysis demonstrated a disturbed spatial orientation of the F-actin cytoskeleton after I/R. Finally, the loss of F-actin correlated with a rise in plasma creatinine.

CONCLUSIONS

The methods of digital image analysis described in the present study demonstrate that renal I/R induces profound changes in the F-actin cytoskeletal structure of microvascular endothelial cells, implicating an injured and dysfunctional microvascular endothelium, which may contribute to acute renal failure (ARF).

The role of procalcitonin in a decision tree for prediction of bloodstream infection in febrile patients

Bloodstream infection (BSI) in febrile patients is associated with high mortality. Clinical and laboratory variables, such as procalcitonin (PCT), may predict BSI and help decision-making concerning empirical treatment. This study compared two models for prediction of BSI, and evaluated the role of PCT vs. clinical variables, collected daily in 300 consecutive febrile inpatients, for 48 h after onset of fever. Multiple logistic regression (MLR) and classification and regression tree (CART) models were compared for discriminatory power and diagnostic performance. BSI was present in 17% of cases. MLR identified the presence of intravascular devices, nadir albumin and thrombocyte counts, and peak temperature, respiratory rate and leukocyte counts, but not PCT, as independent predictors of BSI. In contrast, a peak PCT level of >2.45 ng/mL was the principal discriminator in the decision tree based on CART. The latter was more accurate (94%) than the model based on MLR (72%; p <0.01). Hence, the presence of BSI in febrile patients is predicted more accurately and by different variables, e.g., PCT, in CART analysis, as compared with MLR models. This underlines the value of PCT plus CART analysis in the diagnosis of a febrile patient.

Biomarkers of acute renal injury and renal failure

Acute renal failure (ARF) is a frequent problem in the intensive care unit and is associated with a high mortality. Early recognition could help clinical management, but current indices lack sufficient predictive value for ARF. Therefore, there might be a need for biomarkers in detecting renal tubular injury and/or dysfunction at an early stage before a decline in glomerular filtration rate is noted by an increased serum creatinine. A MEDLINE/PubMed search was performed, including all articles about biomarkers for ARF. All publication types, human and animal studies, or subsets were searched in English language. An extraction of relevant articles was made for the purpose of this narrative review. These biomarkers include tubular enzymes (alpha- and pi-glutathione S-transferase, N-acetyl-glucosaminidase, alkaline phosphatase, gamma-glutamyl transpeptidase, Ala-(Leu-Gly)-aminopeptidase, and fructose-1,6-biphosphatase), low-molecular weight urinary proteins (alpha1- and beta2-microglobulin, retinol-binding protein, adenosine deaminase-binding protein, and cystatin C), Na+/H+ exchanger, neutrophil gelatinase-associated lipocalin, cysteine-rich protein 61, kidney injury molecule 1, urinary interleukins/adhesion molecules, and markers of glomerular filtration such as proatrial natriuretic peptide (1-98) and cystatin C. These biomarkers, detected in urine or serum shortly after tubular injury, have been suggested to contribute to prediction of ARF and need for renal replacement therapy. However, excretion of these biomarkers may also increase after reversible and mild dysfunction and may not necessarily be associated with persistent or irreversible damage. Large prospective studies in human are needed to demonstrate an improved outcome of biomarker-driven management of the patient at risk for ARF.

Heterogeneity and prediction of hemodynamic responses to dobutamine in patients with septic shock

OBJECTIVE

To establish the heterogeneity of hemodynamic responses to dobutamine in patients with septic shock and to identify the predictive factors of these hemodynamic responses.

DESIGN

Prospective study.

SETTING AND PATIENTS

A total of 12 patients with septic shock in a tertiary medical intensive care unit.

INTERVENTIONS

A 20-min dobutamine infusion at 5 microg.kg(-1).min(-1) with subsequent increments to 8, 12.6, and 20 microg.kg(-1).min(-1), on two consecutive days. Responses were dichotomized into changes in heart rate (HR) or stroke volume index (SVI) of >10% and < or =10% at the maximal dobutamine infusion.

MEASUREMENTS AND MAIN RESULTS

No differences were found in survival, Acute Physiology and Chronic Health Evaluation II score, maximal dobutamine doses, or pharmacokinetics of dobutamine between HR and SVI groups. In DeltaHR > 10% vs. DeltaHR < or = 10%, baseline HR was lower, and baseline mixed venous oxygen tension and saturation were higher. During dobutamine infusion, mean arterial pressure decreased in DeltaHR > 10%. Cardiac index and the systemic oxygen delivery index increased and the systemic vascular resistance index decreased at unchanged SVI. Pressure work index increased and the ratio of the diastolic to systolic aortic pressure time indices decreased but not to <0.6. In DeltaHR < or = 10%, systemic vascular resistance index and the ratio of the diastolic to systolic aortic pressure time indices decreased (but remained >0.6) without changes in SVI or cardiac index. Baseline hemodynamic and metabolic variables did not differ between SVI groups. In DeltaSVI > 10%, cardiac index increased with dobutamine, but Pao2 and the systemic oxygen delivery index decreased. In DeltaSVI < or = 10%, HR and the systemic oxygen delivery index increased; mean arterial pressure, left ventricular stroke work index, systemic vascular resistance index, and the ratio of the diastolic to systolic aortic pressure time indices decreased.

CONCLUSIONS

Patients with a positive chronotropic response to dobutamine had lower baseline HR values, and a chronotropic rather than inotropic response predicted an increase in cardiac index and systemic oxygen delivery index. Incremental dosages of dobutamine did not compromise indirectly measured myocardial oxygen balance.

Rho kinase regulates renal blood flow by modulating eNOS activity in ischemia-reperfusion of the rat kidney

Renal ischemia-reperfusion (I/R) results in vascular dysfunction characterized by a reduced endothelium-dependent vasodilatation and subsequently impaired blood flow. In this study, we investigated the role of Rho kinase in endothelial nitric oxide synthase (eNOS)-mediated regulation of renal blood flow and vasomotor tone in renal I/R. Male Wistar rats were subjected to 60-min bilateral clamping of the renal arteries or sham procedure. One hour before the clamping, the Rho kinase inhibitor Y27632 (1 mg/kg) was intravenously infused. After I/R, renal blood flow was measured using fluorescent microspheres. I/R resulted in a 62% decrease in renal blood flow. In contrast, the blood flow decrease in the group treated with the Rho kinase inhibitor (YI/R) was prevented. Endothelium-dependent vasodilatation of renal arcuate arteries to ACh was measured ex vivo in a pressure myograph. These experiments demonstrated that the in vivo treatment with the Rho kinase inhibitor prevented the decrease in the nitric oxide (NO)-mediated vasodilator response. In addition, after I/R renal interlobar arteries showed a decrease in phosphorylated eNOS and vasodilator-stimulated phosphoprotein, a marker for bioactive NO, which was attenuated by in vivo Rho kinase inhibition. These findings indicate that in vivo inhibition of Rho kinase in renal I/R preserves renal blood flow by improving eNOS function.

Extravascular lung water to blood volume ratios as measures of permeability in sepsis-induced ALI/ARDS

OBJECTIVE

We studied the relationship, and the effect of fluid loading on this, between the ratio of extravascular lung water (EVLW) to intrathoracic/pulmonary blood volumes (ITBV, PBV) and the radionuclide pulmonary leak index (PLI) to protein during sepsis-induced acute lung injury/acute respiratory distress syndrome (ALI/ARDS).

DESIGN AND SETTING

A prospective observational study, in the intensive care unit of a university hospital.

PATIENTS

Twenty-two consecutive mechanically ventilated patients with sepsis-related ALI/ARDS from pneumonia (n = 12) or extrapulmonary sources (n = 10), without elevated cardiac filling pressures.

INTERVENTION

Crystalloid (1700-1800 ml) or colloid (1000-1800 ml) fluid loading until target filling pressures.

MEASUREMENTS AND RESULTS

Protein permeability was assessed noninvasively over the lungs with help of 67Ga-labeled transferrin and 99mTc-labeled red blood cells (Pulmonary leak index, upper limit normal 14.1 x 10(-3)/min) and EVLW and blood volumes by the thermal-dye transpulmonary dilution technique before and after fluid loading. Prior to fluids the pulmonary leak index related to the ratio of EVLW/ITBV and EVLW/PBV (r(s) = 0.46) particularly when the pulmonary leak index was below 100 x 10(-3)/min and in extrapulmonary sepsis (PLI vs. EVLW/PBV r(s) = 0.71). Fluid loading did not alter EVLW, EVLW/ITBV, or EVLW/PBV or the relationship to PLI.

CONCLUSION

The data demonstrate that EVLW/ITBV or EVLW/PBV are imperfect measures of increased protein permeability in mechanically ventilated patients with sepsis-induced ALI/ARDS particularly when the PLI is severely increased and during pneumonia, independent of fluid status.

Cardiac response is greater for colloid than saline fluid loading after cardiac or vascular surgery

OBJECTIVE

To study the effects on volume expansion and myocardial function of colloids or crystalloids in the treatment of hypovolaemic hypotension after cardiac and major vascular surgery.

DESIGN AND SETTING

A single-centre, single-blinded, randomized clinical trial at the intensive care unit of a university hospital.

PATIENTS AND METHODS

Patients (n=67) were subjected to a 90-min filling pressure-guided fluid challenge with saline 0.9% or the colloids gelatin 4%, hydroxyethyl starch 6% or albumin 5%. Biochemical variables and haemodynamics (transpulmonary thermodilution) were measured.

RESULTS

An amount of 1800 (1300-1800) ml of saline or 1600 (750-1800) ml of colloid solution (P< 0.005) was infused. Colloid osmotic pressure (COP) decreased in the saline group and increased in the colloid groups (P< 0.001). Plasma volume increased by 3.0% (-18 to 24) in the saline versus 19% (-11 to 50) in the colloid groups (P< 0.001). Cardiac index increased by median 13% (ns) in the saline group and by 22% in the colloid groups (P<0.005). The rise in left ventricular stroke work index was greater in the colloid than in the saline groups. The different colloids were equally effective. The rise in cardiac index related to the rise in plasma volume and global end-diastolic volume, confirming plasma volume and preload augmentation by the fluid loading.

CONCLUSION

After cardiac or major vascular surgery, the pressure- and time-guided fluid response is dependent on the type of fluid used. Colloid fluid loading leads to a greater increase in preload-recruitable cardiac and left ventricular stroke work indices than that with saline, because of greater plasma volume expansion following an increase in plasma COP.

Effect of prior statin therapy on capillary permeability in the lungs after cardiac or vascular surgery

Cholesterol-lowering statins can ameliorate severe forms of vascular hyperpermeability in experimental studies, and may thereby ameliorate acute lung injury and sepsis. It is unknown whether this also applies to humans. This study aimed to define whether or not prior statin therapy reduces mild post-operative increases in pulmonary capillary protein permeability associated with acute lung injury after cardiac or major vascular surgery. A prospective observational study was performed in an intensive care unit of a university hospital on 64 patients, 37 after elective cardiac and 27 after major vascular surgery, of whom 68 and 44%, respectively, had received prior statin therapy. A mobile probe system was used to measure the pulmonary leak index (PLI), i.e. the transvascular transport rate of gallium-67-radiolabelled transferrin. For all of the patients together, the mean PLI did not differ between the statin and control groups (22.9 versus 24.4 x 10(-3) min(-1)). The prevalence of an elevated PLI was 57% in the statin and 59% in the control group. Subgroup analysis did not reveal significant differences caused by statins in the PLI of these patients. Prior statin therapy neither has an adverse effect on mildly increased pulmonary capillary permeability in patients after cardiac or major vascular surgery nor does it ameliorate this increased capillary permeability.

Cardiac output measurement by pulse dye densitometry: comparison with pulmonary artery thermodilution in post-cardiac surgery patients

OBJECTIVE

Pulse-dye densitometry (PDD) could be a suitable, low-invasive alternative to thermodilution using a pulmonary artery catheter (PAC) for monitoring cardiac output. The aim of our study was to assess the reproducibility and validity of PDD compared to PAC-thermodilution.

METHODS

In 43 post-cardiac surgery patients, the mean of triplicate readings of cardiac output was assessed using both methods. In a subgroup of 26 patients, a second set of measurements was obtained on average 2 h later.

RESULTS

Reproducibility of consecutive measurements was slightly better for PAC-thermodilution than for PDD (median coefficient of variation of the triplicate measurements: 3.5% versus 5.4%, P < 0.01). Both methods correlated well (r = 0.84, p < 0.001). Using Bland and Altman analyses with PAC-thermodilution as the reference method, PDD showed a bias of -0.68 +/- 0.82 L/min, mainly due to differences in higher ranges of cardiac output (>6.5 L/min). Measured changes in cardiac output were 81% concordant (i.e. <1 L/min different) between both methods.

CONCLUSION

PDD correlates well with PAC-thermodilution and thus deserves consideration as a low-invasive alternative for measurement and follow-up of cardiac output.

Increased pulmonary capillary permeability and extravascular lung water after major vascular surgery

INTRODUCTION

We decided to investigate the pathogenesis of pulmonary ventilatory and radiographic abnormalities in patients after major vascular surgery.

PATIENTS AND METHODS

Sixteen mechanically ventilated patients without heart failure were studied, within 3 h after major abdominal surgery. We measured extravascular lung water, intrathoracic, global end-diastolic and pulmonary blood volumes, (67)Ga-transferrin pulmonary leak index and ventilatory and radiographic variables. The latter allowed computation of the lung injury score as a measure of lung injury.

RESULTS

The extravascular lung water was elevated (>7 mL kg(-1)) in 5 of 16 patients, while the pulmonary leak index was elevated in 11 patients and a supranormal extravascular lung water was associated with a high pulmonary leak index and higher extravascular lung water relative to intrathoracic blood volume or pulmonary blood volume. Patients were arbitrarily divided into those with a lung injury score >1 and < or =1, and only differed in the factors composing the score as well as in extravascular lung water divided by pulmonary blood volume. A lung injury score >1 was associated with a longer duration of mechanical ventilation.

CONCLUSION

Our data suggest that mild, subclinical, pulmonary oedema is relatively common after major vascular surgery, mainly caused by increased pulmonary capillary permeability in the absence of overt heart failure. However, permeability oedema only partially contributes to postoperative lung injury score and need for mechanical ventilation, suggesting a major contribution by atelectasis.

Effect of fluid loading with saline or colloids on pulmonary permeability, oedema and lung injury score after cardiac and major vascular surgery

BACKGROUND

The optimal type of fluid for treating hypovolaemia without evoking pulmonary oedema is still unclear, particularly in the presence of pulmonary vascular injury, as may occur after cardiac and major vascular surgery.

METHODS

In a single-centre, prospective, single-blinded clinical trial 67 mechanically ventilated patients were randomly assigned to receive saline, gelatin 4%, HES 6% or albumin 5%, according to a 90 min fluid loading protocol with target central venous pressure of 13 and pulmonary capillary wedge pressure of 15 mm Hg, within 3 h after cardiac or major vascular surgery. Before and after the protocol, we recorded haemodynamics and ventilatory variables and took chest radiographs. The pulmonary vascular injury was evaluated using the 67Ga-transferrin pulmonary leak index (PLI) and extravascular lung water (EVLW). Plasma colloid osmotic pressure (COP) was determined and the lung injury score (LIS) was calculated.

RESULTS

More saline was infused than colloid solutions (P<0.005). The COP increased in the colloid groups and decreased in patients receiving saline. Cardiac output increased more in the colloid groups. At baseline, PLI and EVLW were above normal in 60 and 30% of the patients, with no changes after fluid loading, except for a greater PLI decrease in HES than in gelatin-loaded patients. The oxygenation ratio improved in all groups. In the colloid groups, the LIS increased, because of a decrease in total respiratory compliance, probably associated with an increase in intrathoracic plasma volume.

CONCLUSIONS

Provided that fluid overloading is prevented, the type of fluid used for volume loading does not affect pulmonary permeability and oedema, in patients with acute lung injury after cardiac or major vascular surgery, except for HES that may ameliorate increased permeability. During fluid loading, changes in LIS (and respiratory compliance) do not represent changes in pulmonary permeability or oedema.

Simple vs complex radionuclide methods of assessing capillary protein permeability for diagnosing acute respiratory distress syndrome

PURPOSE

Using injection of gallium Ga 67 transferrin, technetium Tc 99m red cells, probes over the lungs, and blood samples, a pulmonary leak index (PLI) and pulmonary transcapillary escape rate (PTCER) for transferrin can be measured. This may help differentiating between cardiogenic pulmonary edema (CPE) and permeability (noncardiogenic) pulmonary edema of the acute respiratory distress syndrome (ARDS). The purpose of the study was to evaluate the relative importance of red cell labeling, blood sampling, and probe measurements in this assessment.

MATERIALS AND METHODS

Analysis of radionuclide data obtained in consecutive patients with radiographic evidence for pulmonary edema, classified as ARDS (n = 13), CPE (n = 8), or mixed (n = 5), was performed. The latter patients met ARDS criteria except for a high pulmonary capillary wedge pressure.

RESULTS

The PLI, PTCER, and the (67)Ga-lung/blood radioactivity increase (without (99m)Tc-red cell data) were specific and sensitive indices to differentiate ARDS/mixed from CPE. The blood transcapillary escape rate (TER) of (67)Ga-transferrin was about 2- to 6-fold higher in ARDS and mixed than in CPE. The TER had similar diagnostic value as the PLI, PTCER, and the (67)Ga-lung/blood radioactivity ratio increase.

CONCLUSIONS

The diagnostic value of the simple blood TER of (67)Ga-transferrin is similar to that of complex methods, using (99m)Tc-red cells and probe measurements over the lungs, because the complex methods largely depend on the blood TER. Simplification of the method without red cell labeling and probes may facilitate bedside use to diagnose permeability edema of ARDS, particularly in the absence of a pulmonary artery catheter.

Pulmonary abnormalities after cardiac surgery are better explained by atelectasis than by increased permeability oedema

BACKGROUND

Cardiac surgery can be complicated by pulmonary abnormalities, but it is unclear how various manifestations interrelate.

METHODS

A prospective study in the intensive care unit was performed on 26 mechanically ventilated patients without cardiac failure within 3 h after elective cardiac surgery involving cardiopulmonary bypass. Oedema (extravascular lung water, EVLW) was measured by the thermal-dye technique and permeability by a dual radionuclide technique, yielding a pulmonary leak index (PLI). Radiographic, mechanical and gas exchange features were used to calculate the lung injury score (LIS), ranging between 0 and 4. Evidence for left lower lobe atelectasis was obtained from plain radiographs. The plasma colloid osmotic pressure (COP) was measured by an oncometer.

RESULTS

The EVLW (normal, <7 ml/kg) was elevated in 36% of patients and the PLI (normal, <14.1 x 10(-3)/min) in 44%, but the variables did not interrelate directly. Patients with a supranormal EVLW had a lower COP than patients with normal EVLW. The duration of mechanical ventilation was prolonged in patients (20%) with EVLW > 10 ml/kg. There was no difference in EVLW and PLI in patients with LIS < 1 and LIS > 1 (31% of patients). In patients with radiographic evidence for atelectasis (46%), the positive end-expiratory pressure and inspiratory O2 fraction to maintain oxygenation were higher than in those without.

CONCLUSIONS

After cardiac surgery, mild pulmonary oedema is relatively common, even in the absence of high filling pressures, and is mainly attributable to a low COP, irrespective of increased permeability in about one-half of patients. It may prolong mechanical ventilation at EVLW > 10 ml/kg. However, pulmonary radiographic and ventilatory abnormalities may result, at least in part, from atelectasis rather than increased permeability oedema.

Induced nitric oxide impairs relaxation but not contraction in endotoxin-exposed rat pulmonary arteries

BACKGROUND

Many patients with severe acute lung injury do not respond to nitric oxide (NO) inhalational therapy with alleviation of pulmonary arterial hypertension and hypoxemia, so this treatment remains controversial. MATERIALS AND METHODS.: We investigated in endotoxin-exposed Wistar rat pulmonary arteries whether endogenous NO alters contractile and relaxing responses, by electrochemical NO and isometric force measurements.

RESULTS

Receptor-independent contraction was similar in control and endotoxin-exposed arteries, while thromboxane analogue (TxA)-dependent contraction was less in the latter. Neither non-selective NO synthase (NOS) inhibition by N(G)-nitro-l-arginine (l-NA) or selective inducible-NOS2 inhibition by aminoguanidine (AG) improved TxA-induced contraction in endotoxin-exposed arteries. Acetylcholine-induced relaxation was impaired in endotoxin-exposed pulmonary arteries, despite a comparable acetylcholine-induced NO release in control arteries. Additionally, NO solution-induced relaxation of endotoxin-exposed arteries was impaired, but could be improved by l-NA or AG. Application of a phosphodiesterase-insensitive cyclic guanosine monophosphate analogue induced similar relaxation in both control and endotoxin-exposed arteries.

CONCLUSIONS

Endotoxin-associated NOS2-derived NO is thus associated with impaired NO-mediated relaxation, but does not underlie reduced receptor-mediated pulmonary contractile responses. An increased phosphodiesterase activity may underlie the former, so this route can be explored to replace or improve the effect of inhalational NO therapy in severe sepsis-induced acute lung injury in patients.

Mechanical ventilation and acute renal failure

OBJECTIVE

To review the current literature on possible mechanisms by which mechanical ventilation may initiate or aggravate acute renal failure.

DATA SOURCE

A Medline database and references from identified articles were used to perform a literature search relating to mechanical ventilation and acute renal failure.

DATA SYNTHESIS

Acute renal failure may be initiated or aggravated by mechanical ventilation through three different mechanisms. First, strategies such as permissive hypercapnia or permissive hypoxemia may compromise renal blood flow. Second, through effects on cardiac output, mechanical ventilation affects systemic and renal hemodynamics. Third, mechanical ventilation may cause biotrauma-a pulmonary inflammatory reaction that may generate systemic release of inflammatory mediators. The harmful effects of mechanical ventilation may become more significant when a comorbidity is present. In these situations, it is more difficult to maintain normal gas exchange, and moderate arterial hypoxemia and hypercapnia are often accepted. Renal blood flow is compromised due to a decreased cardiac output as a consequence of high intrathoracic pressures. Furthermore, the effects of biotrauma are not limited to the lungs but may lead to a systemic inflammatory reaction.

CONCLUSIONS

The development of acute renal failure during mechanical ventilation likely represents a multifactorial process that may become more important in the presence of comorbidities. Development of optimal interventional strategies requires an understanding of physiologic principles and greater insight into the precise molecular and cellular mechanisms that may also play a role.

Sequential organ failure predicts mortality of patients with a haematological malignancy needing intensive care

OBJECTIVES

Poor survival of patients with a haematological malignancy admitted to the intensive care unit (ICU) prompts for proper admission triage and prediction of ICU treatment failure and long-term mortality. We therefore tried to find predictors of the latter outcomes.

METHODS

A retrospective analysis of charts and a prospective follow-up study were done, of haemato-oncological patients, admitted to our ICU in a 7-year period with a follow-up until 2 yr thereafter. Clinical parameters during the first four consecutive days were taken to calculate the simplified acute physiology (SAPS II) and the sequential organ failure assessment (SOFA) scores, of proven predictive value in general ICU populations.

RESULTS

From a total of 58 patients (n = 47 with acute myelogenous leukaemia or non-Hodgkin lymphoma), admitted into ICU mostly because of respiratory insufficiency, sepsis, shock or combinations, 36 patients had died during their stay in the ICU. Of ICU survivors (n = 22), 20 patients died during follow-up so that the 1-year survival rate was only 12%. The SAPS II and particularly the SOFA scores were of high predictive value for ICU and long-term mortality.

CONCLUSIONS

Patients with life-threatening complications of haematological malignancy admitted to ICU ran a high risk for death in the ICU and on the long-term, and the risk can be well predicted by SOFA. The latter may help us to decide on intensive care in individual cases, in order to avoid potentially futile care for patients with a SOFA score of 15 or higher.

Long-term outcome after 60 days of intensive care

Patients with a long stay in the intensive care unit because of chronic critical illness consume many resources, and yet their outcome may be poor. We evaluated the long-term outcome of patients spending more than 60 days in the intensive care unit. We performed a retrospective cohort and prospective follow-up study of 78 patients staying more than 60 days in the 19-26 bed mixed intensive care unit of a university hospital from November 1995 to January 2003. The mortality in the intensive care unit was 38%; at 1 and 5 years it was 56% and 67%, respectively. Advanced age, prior pulmonary disease, long duration of renal replacement therapy, a low oxygenation ratio and platelet count and high Simplified Acute Physiology Score II and Sequential Organ Failure Assessment scores on day 60 influenced long-term mortality. A Simplified Acute Physiology Score II of 50 or a Sequential Organ Failure Assessment score of 8 or higher was associated with 100% mortality during follow-up. The overall 5-year survival rate of 33% suggests that prolonged intensive care may be worth the effort in certain patients.

Molecular mechanisms of acute renal failure following ischemia/reperfusion

Acute renal failure (ARF) necessitating renal replacement therapy is a common problem associated with high morbidity and mortality in the critically ill. Hypotension, followed by resuscitation, is the most common etiologic factor, mimicked by ischemia/reperfusion (I/R) in animal models. Although knowledge of the pathophysiology of ARF in the course of this condition is increasingly detailed, the intracellular and molecular mechanisms leading to ARF are still incompletely understood. This review aims at describing the role of cellular events and signals, including collapse of the cytoskeleton, mitochondrial and nuclear changes, in mediating cell dysfunction, programmed cell death (apoptosis), necrosis and others. Insight into the molecular pathways in the various elements of the kidney, such as vascular endothelium and smooth muscle and tubular epithelium leading to cell damage upon I/R will, hopefully, open new therapeutic modalities, to mitigate the development of ARF after hypotensive episodes and to promote repair and resumption of renal function once ARF has developed.

Endemic multidrug-resistant Pseudomonas aeruginosa in critically ill patients

OBJECTIVE

To describe the epidemiology of endemic multidrug-resistant Pseudomonas aeruginosa colonizations and infections in critically ill patients.

DESIGN

Prospective study on bacterial strain typing and retrospective cohort study of charts of patients in the intensive care unit (ICU).

PATIENTS

Fifty-three patients with P. aeruginosa isolated from clinical cultures in 2001 were selected, divided into those with P. aeruginosa in vitro resistant to at least two classes of antibiotics (multidrug-resistant, n = 18) and those susceptible to all or resistant to only one antibiotic (susceptible, n = 35).

RESULTS

Risk factors for multidrug-resistant P. aeruginosa included maxillary sinusitis, long-dwelling central venous catheters, prolonged use of certain antibiotics, a high lung injury score, and prolonged mechanical ventilation and duration of stay. The frequency of colonization (approximately 50%) versus infection (ie, ventilator-associated pneumonia) did not differ between the groups. On amplified fragment-length polymorphism analysis, 64% of the multidrug-resistant strains had been potentially transmitted via cross-colonization and 36% had probably originated endogenously. ICU mortality was 22% in the multidrug-resistant group and 23% in the susceptible group, although the duration of mechanical ventilation was longer in the former.

CONCLUSIONS

Patients with sinusitis who stayed in the ICU longer, were ventilated longer because of acute lung injury, received antibiotics for longer durations, and had long-dwelling central venous catheters ran an elevated risk of acquiring multidrug-resistant P. aeruginosa. These patients did not have a higher mortality than patients with susceptible P. aeruginosa. Prevention of the emergence of multidrug-resistant strains requires changes in infection control measures and antibiotic policies in our ICU.

Acute lung injury, overhydration or both?

Acute lung injury or acute respiratory distress syndrome (ALI/ARDS) in the course of sepsis is thought to result from increased pulmonary capillary permeability and resultant edema. However, when the edema is assessed at the bedside by measuring the extravascular thermal volume by transpulmonary dilution, some ALI/ARDS patients with sepsis may have normal extravascular lung water (EVLW). Conversely, a raised EVLW may be present even when criteria for ALI/ARDS are not met, according to GS Martin and colleagues in this issue of Critical Care. This commentary puts the findings into a broader perspective and focuses on the difficulty, at the bedside, in recognizing and separating various types of pulmonary edema. Some of these forms of edema, classically differentiated on the basis of increased permeability and cardiogenic/hydrostatic factors, may overlap, whereas the criteria for ALI/ARDS may be loose, poorly reproducible, relatively insensitive and nonspecific, and highly therapy-dependent. Overhydration is particularly difficult to recognize. Additional diagnostics may be required to improve the delineation of pulmonary edema so as to redirect or redefine treatment and improve patient morbidity and, perhaps, mortality. Monitoring EVLW by single transpulmonary thermal dilution, for instance, might have a future role in this process.

Smooth muscle F-actin disassembly and RhoA/Rho-kinase signaling during endotoxin-induced alterations in pulmonary arterial compliance

Endotoxemia is associated with changed pulmonary vascular function with respect to vasoreactivity, endothelial permeability, and activation of inducible nitric oxide synthase II (NOSII). However, whether altered passive arterial wall mechanics contribute to this endotoxin-induced pulmonary vascular dysfunction is still unknown. Therefore, we investigated whether endotoxin affects the passive arterial mechanics and compliance of isolated rat pulmonary arteries. Pulmonary arteries of pentobarbital-anesthetized Wistar rats ( n = 55) were isolated and exposed to Escherichia coli endotoxin (50 μg/ml) for 20 h. Endotoxin increased pulmonary artery diameter and compliance (transmural pressure = 13 mmHg) in an endothelium-, Ca2+-, or NOSII-induced NO release-independent manner. Interestingly, the endotoxin-induced alterations in the passive arterial mechanics were accompanied by disassembly of the smooth muscle cell (SMC) F-actin cytoskeleton. Disassembly of F-actin by incubation of control arteries with the cytoskeleton-disrupting agent cytochalasin B or the Rho-kinase inhibitor Y-27632 induced a similar increase in passive arterial diameter and compliance. In contrast, RhoA activation by lysophosphatidic acid prevented the endotoxin-induced alterations in the pulmonary SMC F-actin cytoskeleton and passive mechanics. In conclusion, these findings indicate that disassembly of the SMC F-actin cytoskeleton and RhoA/Rho-kinase signaling act as mediators of endotoxin-induced changes in the pulmonary arterial mechanics. They imply the involvement of F-actin rearrangement and RhoA/Rho-kinase signaling in endotoxemia-induced vascular lung injury.

Myocardial O2 consumption in porcine left ventricle is heterogeneously distributed in parallel to heterogeneous O2 delivery

Myocardial blood flow is unevenly distributed, but the cause of this heterogeneity is unknown. Heterogeneous blood flow may reflect heterogeneity of oxygen demand. The aim of the present study was to assess the relation between oxygen consumption and blood flow in small tissue regions in porcine left ventricle. In seven male, anesthetized, open-chest pigs, local oxygen consumption was quantitated by computational model analysis of the incorporation of 13C in glutamate via the tricarboxylic acid cycle during timed infusion of [13C]acetate into the left anterior descending coronary artery. Blood flow was measured with radioactive microspheres before and during acetate infusion. High-resolution nuclear magnetic resonance 13C spectra were obtained from extracts of tissue samples (159 mg mean dry wt) taken at the end of the acetate infusion. Mean regional myocardial blood flow was stable [5.0 ± 1.6 (SD) and 5.0 ± 1.4 ml·min−1·g dry wt−1 before and after 30 min of acetate infusion, respectively]. Mean left ventricular oxygen consumption measured with the NMR method was 18.6 ± 7.7 μmol·min−1·g dry wt−1 and correlated well ( r = 0.85, P = 0.02, n = 7) with oxygen consumption calculated from blood flow, hemoglobin, and blood gas measurements (mean 22.8 ± 4.7 μmol·min−1·g dry wt−1). Local blood flow and oxygen consumption were significantly correlated ( r = 0.63 for pooled normalized data, P < 0.0001, n = 60). We calculate that, in the heart at normal workload, the variance of left ventricular oxygen delivery at submilliliter resolution is explained for 43% by heterogeneity in oxygen demand.

Respiratory herpes simplex virus type 1 infection/colonisation in the critically ill: marker or mediator?

BACKGROUND

The clinical significance and pulmonary pathogenicity of herpes simplex virus type 1 (HSV-1) in mechanically ventilated, critically ill patients are unclear.

OBJECTIVE

To determine the clinical features and course of respiratory HSV-1 infections/colonisations in the critically ill, in order to evaluate the contribution to outcome.

DESIGN

A retrospective cohort study in the intensive care unit of an university hospital, involving 22 patients with a HSV-1 isolated from bronchoalveolar lavage (BAL) fluid, divided into survivors (n = 13) and non-survivors (n = 9). All patients except for one survivor had been intubated and were mechanically ventilated.

RESULTS

Non-survivors had acquired HSV-1 sooner on mechanical ventilation than survivors. Prior chronic heart disease was more prevalent in non-survivors than in survivors and, at the time of HSV-1 isolation, the mean creatinine level was higher (P < 0.05) in the former. Survivors had a somewhat greater fall in body temperature after a 10-day course of antiviral therapy than non-survivors, but the lung radiographic abnormalities prior to and after the course did not differ. There were no major differences in cardiorespiratory variables between outcome groups and causes of death and were judged not to relate, in general, to HSV-1.

CONCLUSIONS

Critically ill patients in whom HSV-1 from BAL is isolated, have about 40% chance of dying, mainly because of severe underlying disease and comorbidity, which may predispose to endogenous reactivation of the virus. There is no clinical evidence for direct cardiorespiratory pathogenicity and beneficial effects of antiviral therapy. HSV-1 isolated from lung secretions may thus be a marker rather than a mediator of severe illness.

Mannan binding lectin in febrile adults: no correlation with microbial infection and complement activation

AIMS

To study the role of the mannan binding lectin (MBL) pathway of complement activation in the host defence to microbial infection in vivo, and the role of MBL in infectious mortality in non-selected patients.

METHODS

A prospective observational study on 177 hospitalised medical patients with new onset fever. The presence, origin, and microbial cause of infection, the circulating MBL and complement activation product 3a (C3a), and the 28 day hospital course were determined.

RESULTS

The patients had median MBL values similar to healthy blood donors: 18% of the patients and 14% of the blood donors had MBL deficiency, with values below 0.1 microg/ml. Median C3a was higher in patients with microbiologically confirmed infection than in those without, whereas there was no difference in MBL values or frequency of deficiency among patient groups with or without positive local cultures or bacteraemia. The mortality rate was 8% and the outcome groups did not differ in MBL. In febrile adults hospitalised in internal medicine wards, microbial infection induces complement activation, independently of MBL.

CONCLUSIONS

The results argue against a predominant role for the MBL pathway of complement activation and a deficiency of MBL predisposing to serious and invasive microbial infection in non-selected adults.

Elevated nucleosome levels in systemic inflammation and sepsis

OBJECTIVE

Multiple organ dysfunction syndrome is a frequent complication of severe sepsis and septic shock and has a high mortality. We hypothesized that extensive apoptosis of cells might constitute the cellular basis for this complication.

DESIGN

Retrospective study.

SETTING

Medical and surgical wards or intensive care units of two university hospitals.

PATIENTS

Fourteen patients with fever, 15 with systemic inflammatory response syndrome, 32 with severe sepsis, and eight with septic shock.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We assessed circulating levels of nucleosomes, specific markers released by cells during the later stages of apoptosis, with a previously described enzyme-linked immunosorbent assay in these 69 patients with fever, systemic inflammatory response syndrome, severe sepsis, or septic shock. Severity of multiple organ dysfunction syndrome was assessed with sepsis scores, and clinical and laboratory variables. Elevated nucleosome levels were found in 64%, 60%, 94%, and 100% of patients with fever, systemic inflammatory response syndrome, severe sepsis, or septic shock, respectively. These levels were significantly higher in patients with septic shock as compared with patients with severe sepsis, systemic inflammatory response syndrome, or fever, and in nonsurvivors as compared with survivors. In patients with advanced multiple organ dysfunction syndrome, nucleosome levels correlated with cytokine plasma levels as well as with variables predictive for outcome.

CONCLUSIONS

Patients with severe sepsis and septic shock have elevated plasma levels of nucleosomes. We suggest that apoptosis, probably resulting from exposure of cells to excessive amounts of inflammatory mediators, might by involved in the pathogenesis of multiple organ dysfunction syndrome.

Effect of sevoflurane on the ex vivo secretion of TNF-alpha during and after coronary artery bypass surgery

BACKGROUND AND OBJECTIVE

Sevoflurane has been used for the induction and maintenance of anaesthesia during cardiac surgery owing to its favourable haemodynamic effects. It has been suggested that it offers protection against myocardial ischaemia-reperfusion injury.

METHODS

We investigated the effect of sevoflurane on plasma concentrations of tumour necrosis factor-alpha (TNF-alpha) after ex vivo stimulation of whole-blood leukocytes by lipopolysaccharide from 20 patients undergoing coronary artery bypass surgery. The patients were randomized to two groups. Group 1 patients were induced and maintained with sevoflurane; those in Group 2 were anaesthetized with moderate doses of midazolam-sufentanil. Blood samples were drawn from the patients on seven occasions from before induction of anaesthesia until 24 h after skin closure.

RESULTS

Plasma concentrations of TNF-alpha were lower in Group 1 than in Group 2 after cessation of cardiopulmonary bypass (median (interquartiles): 25 (21-30) versus 37 (28-79) pg mL(-1); P < 0.05) and 24h after skin closure (196 (100-355) versus 382 (233-718) pg mL(-1); P < 0.05). Postoperatively, two cases of myocardial infarction were recorded, one in each group. Six patients in Group 2 needed continued inotropic support after the first morning to maintain haemodynamic stability versus one patient in Group 1 (P < 0.05). The length of stay in the intensive care unit was significantly lower in Group 1 than in Group 2 (mean +/- SD: 25 +/- 16 versus 54 +/- 30 h; P < 0.05).

CONCLUSIONS

Sevoflurane reduces production of TNF-alpha more than total intravenous anaesthesia with midazolam-sufentanil during cardiac surgery. This may reduce cardiac morbidity and the length of stay in the intensive care unit.

Endotoxin impairs endothelium-dependent vasodilation more in the coronary and renal arteries than in other arteries of the rat

Endotoxemia may result in endothelial dysfunction, and some vascular beds may be affected more than others. To test this hypothesis, we studied, in vitro, the reactivity of isolated rat coronary, renal, superior mesenteric, and hepatic arteries exposed to endotoxin (E. coli, 50 microg. mL(-1)) or saline for 2 h at 37 degrees C. Vascular smooth muscle function was tested using 125 mM KCl, the vasoconstrictors norepinephrine (NE), and the thromboxane analog U46619 (coronary artery). Endothelium-dependent vasorelaxation was tested with acetylcholine (ACh) in preconstricted vessels. Although differing between vessel types, the smooth muscle contractile responses were not affected by endotoxin, either in the presence or absence of L-arginine. Endotoxin impaired the response to ACh in rat coronary arteries (92.7 +/- 4.6% vasodilation in control and 41.3 +/- 11.6% in endotoxin-exposed segments) and in renal arteries (66.7 +/- 5.2% vasodilation in control and 43.2 +/- 4.9% in endotoxin-exposed segments), so that there was a mean 55% decrease vs controls in coronary and a mean 35% decrease in renal arteries. Endotoxin did not affect superior mesenteric and hepatic arteries. Brief endotoxin exposure of isolated rat arteries may thus inactivate endothelial NO synthase, independent of iNOS. The increase in heterogeneity among endothelium-dependent vasodilation after endotoxin may help to explain early blood flow maldistribution in endotoxin shock.

Circulating inflammatory mediators predict shock and mortality in febrile patients with microbial infection

The host response to microbial infection is associated with the release of inflammatory mediators. We hypothesized that the type and degree of the systemic response as reflected by levels of circulating mediators predict morbidity and mortality, according to the invasiveness of microbial infection. We prospectively studied 133 medical patients with fever and culture-proven microbial infection. For 3 days after inclusion, the circulating levels of activated complement C3a, interleukin (IL)-6, and secretory phospholipase A(2) (sPLA(2)) were determined daily. Based on results of microbiological studies performed for up to 7 days, patients were classified as having local infections (Group 1, n = 80 positive local cultures or specific stains for fungal or tuberculous infections) or bacteremia (Group 2, n = 52 plus 1 patient with malaria parasitemia). Outcome was assessed as the development of septic shock and as mortality up to 28 days after inclusion. Fifteen patients (11%) developed septic shock and overall mortality was 18% (n = 24). Bacteremia was associated with shock and shock predisposed to death. Circulating mediator levels were generally higher in Group 2 than in Group 1. Circulating levels of IL-6 and sPLA(2) were higher in patients developing septic shock and in nonsurvivors, particularly in Group 1. High C3a was particularly associated with nonsurvival in Group 2. In Group 1, the area under the curve (AUC) of the receiver operating characteristic (ROC) curve for the peak sPLA(2) for shock development was 0.79 (P < 0.05). The AUC of the ROC curve of the peak IL-6 and sPLA(2) for mortality was 0.69 and 0.68 (P < 0.05), respectively. In Group 2, the AUC of the ROC for peak C3a predicting mortality was 0.73 (P < 0.05). In conclusion, in medical patients with fever and microbial infection, the systemic inflammatory host response predicts shock and death, at an early stage, dependent on the invasiveness of microbial infection. The results suggest a differential pathogenetic role of complement activation on the one hand and release of cytokine and lipid mediators on the other in bacteremic and local microbial infections, respectively. They may partly explain the failure of strategies blocking proinflammatory cytokines or sPLA(2) in human sepsis and may extend the basis for attempts to inhibit complement activation at an early stage in patients at risk of dying from invasive microbial infections.

Luminal endotoxin modifies reaction to gut ischaemia–reperfusion injury in the pig

Background

Translocation of bacteria and their products through the intestinal mucosa during ischaemia–reperfusion (I/R) may contribute to gut I/R injury.

Methods

In order to study the role of luminal endotoxin in gut I/R injury, two groups of seven germ-free pigs each were studied by clamping of the superior mesenteric artery, with and without luminal administration of endotoxin. Two control groups of seven germ-free pigs, with and without endotoxin, were not clamped. Translocation of an inert indicator (polyethyleneglycol (PEG) 3350), mucosal ischaemia (measured by tonometry) and haemodynamics were assessed.

Results

Both clamped groups showed ischaemic injury as measured by raised PEG 3350 urinary levels, lowered intestinal pH, and increased intramucosal arterial and intramucosal portal partial pressure of carbon dioxide gradients. Luminal endotoxin application did not aggravate this I/R injury, nor did it influence haemodynamics. The PEG 3350 level in the clamped endotoxin group was significantly lower than that in the clamped control group (mean(s.d.) 0·55(0·37) versus 1·82(0·70); P = 0·001), suggesting a blunting influence of endotoxin on the I/R injury. This might be explained by a desensitizing effect on leucocytes in the gut wall by luminal endotoxin before clamping and diminishing the I/R-induced production of cytokines in the gut wall.

Conclusion

Endotoxin does not significantly mediate gut I/R injury in the pig and might desensitize the gut wall leucocytes, resulting in decreased translocation of large molecules, including bacterial products and endotoxin.

Unusual association of Hodgkin's disease and sarcoidosis

We report a 51-year-old patient who developed abdominal lymphadenopathy following Hodgkin's disease seven years after she was diagnosed as having sarcoidosis. The patient had been treated with steroids, methotrexate and azathioprine. After three cycles of chemotherapy for Hodgkin's disease, the patient again developed sarcoidosis in the mediastinal lymph nodes. A greater awareness of the co-existence of sarcoidosis and Hodgkin's disease could circumvent the diagnostic difficulties.

Vascular pharmacology of acute lung injury and acute respiratory distress syndrome

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) following sepsis, major trauma and surgery are leading causes of respiratory insufficiency, warranting artificial ventilation in the intensive care unit. It is caused by an inflammatory reaction in the lung upon exogenous or endogenous etiologies eliciting proinflammatory factors, and results in increased alveolocapillary permeability and protein-rich alveolar edema. The interstitial and alveolar inflammation and edema alter ventilation perfusion matching, gas exchange and mechanical properties of the lung. The current therapy of the condition is supportive, paying careful attention to fluid balance, relieving the increased work of breathing and improving gas exchange by mechanical ventilation, but in vitro, animal and some clinical research is done to evaluate the value of anti-inflammatory therapies on morbidity and outcome, including inflammatory cell-stabilizing corticosteroids, xanthine derivates, prostanoids and inhibitors, O(2) radical scavenging factors such as N-acetylcysteine, surfactant replacement, vasodilators including inhaled nitric oxide, vasoconstrictors such as almitrine, and others. None of these compounds has been proven to benefit survival in patients, however, even though carrying a physiologic benefit, except perhaps for steroids that may improve outcome in the later stage of ARDS. This partly relates to the difficulty to assess the lung injury at the bedside, to the multifactorial pathogenesis and the severity of comorbidity, adversely affecting survival.

[Acute respiratory distress syndrome more frequently diagnosed in intensive care patients in the Netherlands than would occur according to internationally established criteria]

OBJECTIVE

To determine the agreement of the diagnosis 'acute respiratory distress syndrome' (ARDS) established by intensive care (IC) specialists, with that according to internationally accepted objective criteria.

DESIGN

Descriptive inventory.

METHOD

All 119 hospitals in the Netherlands with an IC department were asked to participate; 34 did (29%). On 3 consecutive days, IC specialists completed a case-record form concerning the respiratory status and additional treatment of all of their patients. In the case of mechanical ventilation, the specialist could indicate whether ARDS or another condition was the cause of the respiratory insufficiency. In addition to this, objective data were requested so that the investigators could establish whether there was ARDS on the basis of the North American-European Consensus Conference (NAECC) criteria and the less generally accepted 'Lung injury score' (LIS > or = 2.5).

RESULTS

Of the 266 patients about whom a case record form was returned, 151 were mechanically ventilated. ARDS was diagnosed in 36 of these patients according to the IC specialists, in 24 according to the NAECC and in 20 according to the LIS criteria (p < 0.05 versus IC specialists). The chance-corrected agreement (kappa) between the diagnoses by IC specialists and the NAECC criteria was 0.34 (p < 0.001) and between the IC specialists and the LIS 0.44 (p < 0.001). The kappa between the NAECC and the LIS diagnoses was 0.42 (p < 0.001). Using NAECC and/or LIS criteria as the golden standard, a correct ARDS diagnosis was made by the IC specialists in the case of 20 patients, a false-positive diagnosis in the case of 16 patients and a false-negative diagnosis in the case of 13 patients.

CONCLUSION

In this investigation, the diagnosis of ARDS was more frequently established than would occur according to the NAECC criteria.

Cold storage sensitizes rat femoral artery to an endotoxin-induced decrease in endothelium-dependent relaxation

Cold-stored arteries, tissues or organs are transferred in vascular, reconstructive and transplantation surgery. The function of transferred vessels and tissues diminishes when infection complicates transplantation, thereby contributing to morbidity. To evaluate the mechanisms involved, the effects of cold storage on basal vascular reactivity and the sensitivity to the vascular effects of endotoxin were tested in isolated rat femoral artery segments. A crossover design was followed, so that prior to cold storage 4 vessels were incubated for 2 h at 37 degrees C with endotoxin (Escherichia coli 0127:B8, 50 microg mL(-1)) in Krebs solution and 4 with Krebs solution only, while, after cold storage, segments from the former vessels were incubated with Krebs solution only and segments from the latter with endotoxin in Krebs solution. Vascular reactivity was tested in a wire myograph by the addition of depolarizing 125 mM KCl or norepinephrine (NE) as well as the endothelium-dependent vasodilator acetylcholine (ACh) and endothelium-independent vasodilator sodium nitroprusside (SNP). Cold storage did not affect vascular reactivity in the absence of endotoxin. Endotoxin decreased maximum response to NE prior to storage and sensitivity to SNP prior to and after cold storage. After cold storage, endotoxin decreased relaxation to ACh and increased vasoconstriction in response to KCl and NE (P < 0.05). We conclude that cold storage does not alter endothelial and smooth muscle function but sensitizes rat femoral artery to an endotoxin-induced decrease in endothelium-dependent relaxation and thereby to an increase in vasoconstrictor responses, whereas endotoxin alone only decreases receptor-dependent vasoconstrictor responses and sensitivity to NO donors. This may explain in part the detrimental effect of infection on function of cold-stored arterial grafts and tissue/organ transfers.

Tumor necrosis factor-alpha impairs endothelium-dependent relaxation of rat renal arteries, independent of tyrosine kinase

We hypothesized that tumor necrosis factor-alpha (TNF-alpha) mimics endotoxin in attenuating endothelium-dependent vasodilation and smooth muscle constriction of rat renal arteries, and that tyrosine kinase is involved. Isolated rat renal arteries (n =6 per group), pretreated for 2 h by genistein (4',5,7-trihydroxyisoflavone, 10 microg/mL, a tyrosine kinase inhibitor) or vehicle, were exposed for 2 h to recombinant human (rh) TNF-alpha (100 ng/mL) or vehicle. rhTNF-alpha attenuated (P < 0.05) the constriction response to depolarizing 125 mM KCl (952.6+/-125.3 mg/mm vs. 1191.4+/-136.8 mg/mm in rhTNF-alpha-exposed and control segments, respectively), but did not affect the constriction response to norepinephrine (NE, 0.01-10 microM). Genistein did not affect the constriction response to KCl. The concentration-response relation to NE in genistein-pretreated control segments showed (P < 0.05) a rightward shift, while the maximum constriction was not affected. Genistein did not prevent a reduction (P < 0.05) by rhTNF-alpha in the maximum response to NE (721.7+/-42.4 mg/mm vs. 999.8+/-84.4 mg/mm in controls). The endothelium-dependent relaxation induced by (acetyl choline) ACh (0.001-1.0 microM) was attenuated (P < 0.05) by rhTNF-alpha (39.4%+/-6.7% and 77.4%+/-10.0% in rhTNF-alpha-exposed and control segments, respectively). The reduction (P < 0.05) in maximum ACh-induced relaxation after exposure to rhTNF-alpha was not affected by genistein (44.6%+/-3.4% and 70.8% x 2.2% in genistein-pretreated rhTNF-alpha-exposed and control segments, respectively). Hence, the attenuated endothelium-dependent relaxation and smooth muscle constriction of rat renal arteries following short-term rhTNF-alpha exposure, mimicking the effect of endotoxin, does not involve the activity of tyrosine kinase. The latter may be involved in pharmacomechanical coupling, by increasing Ca2+ sensitivity, but less in the electromechanical coupling of smooth muscle constriction.