Peter Pickkers

Decontamination of the Digestive Tract and Oropharynx in ICU Patients

BACKGROUND Selective digestive tract decontamination (SDD) and selective oropharyngeal decontamination (SOD) are infection-prevention measures used in the treatment of some patients in intensive care, but reported effects on patient outcome are conflicting. METHODS We evaluated the effectiveness of SDD and SOD in a crossover study using cluster randomization in 13 intensive care units (ICUs), all in The Netherlands. Patients with an expected duration of intubation of more than 48 hours or an expected ICU stay of more than 72 hours were eligible. In each ICU, three regimens (SDD, SOD, and standard care) were applied in random order over the course of 6 months. Mortality at day 28 was the primary end point. SDD consisted of 4 days of intravenous cefotaxime and topical application of tobramycin, colistin, and amphotericin B in the oropharynx and stomach. SOD consisted of oropharyngeal application only of the same antibiotics. Monthly point-prevalence studies were performed to analyze antibiotic resistance. RESULTS A total of 5939 patients were enrolled in the study, with 1990 assigned to standard care, 1904 to SOD, and 2045 to SDD; crude mortality in the groups at day 28 was 27.5%, 26.6%, and 26.9%, respectively. In a random-effects logistic-regression model with age, sex, Acute Physiology and Chronic Health Evaluation (APACHE II) score, intubation status, and medical specialty used as covariates, odds ratios for death at day 28 in the SOD and SDD groups, as compared with the standard-care group, were 0.86 (95% confidence interval [CI], 0.74 to 0.99) and 0.83 (95% CI, 0.72 to 0.97), respectively. CONCLUSIONS In an ICU population in which the mortality rate associated with standard care was 27.5% at day 28, the rate was reduced by an estimated 3.5 percentage points with SDD and by 2.9 percentage points with SOD. (Controlled Clinical Trials number, ISRCTN35176830.)

A subset of neutrophils in human systemic inflammation inhibits T cell responses through Mac-1

Suppression of immune responses is necessary to limit damage to host tissue during inflammation, but it can be detrimental in specific immune responses, such as sepsis and antitumor immunity. Recently, immature myeloid cells have been implicated in the suppression of immune responses in mouse models of cancer, infectious disease, bone marrow transplantation, and autoimmune disease. Here, we report the identification of a subset of mature human neutrophils (CD11cbright/CD62Ldim/CD11bbright/CD16bright) as what we believe to be a unique circulating population of myeloid cells, capable of suppressing human T cell proliferation. These cells were observed in humans in vivo during acute systemic inflammation induced by endotoxin challenge or by severe injury. Local release of hydrogen peroxide from the neutrophils into the immunological synapse between the neutrophils and T cells mediated the suppression of T cell proliferation and required neutrophil expression of the integrin Mac-1 (αMβ2). Our data demonstrate that suppression of T cell function can be accomplished by a subset of human neutrophils that can be systemically induced in response to acute inflammation. Identification of the pivotal role of neutrophil Mac-1 and ROS in this process provides a potential target for modulating immune responses in humans.

A unified theory of sepsis-induced acute kidney injury: inflammation, microcirculatory dysfunction, bioenergetics, and the tubular cell adaptation to injury.

ABSTRACT Given that the leading clinical conditions associated with acute kidney injury (AKI), namely, sepsis, major surgery, heart failure, and hypovolemia, are all associated with shock, it is tempting to attribute all AKI to ischemia on the basis of macrohemodynamic changes. However, an increasing body of evidence has suggested that in many patients, AKI can occur in the absence of overt signs of global renal hypoperfusion. Indeed, sepsis-induced AKI can occur in the setting of normal or even increased renal blood flow. Accordingly, renal injury may not be entirely explained solely on the basis of the classic paradigm of hypoperfusion, and thus other mechanisms must come into play. Herein, we put forward a “unifying theory” to explain the interplay between inflammation and oxidative stress, microvascular dysfunction, and the adaptive response of the tubular epithelial cell to the septic insult. We propose that this response is mostly adaptive in origin, that it is driven by mitochondria, and that it ultimately results in and explains the clinical phenotype of sepsis-induced AKI.

Assessment of the worldwide burden of critical illness: the Intensive Care Over Nations (ICON) audit

BACKGROUND Global epidemiological data regarding outcomes for patients in intensive care units (ICUs) are scarce, but are important in understanding the worldwide burden of critical illness. We, therefore, did an international audit of ICU patients worldwide and assessed variations between hospitals and countries in terms of ICU mortality. METHODS 730 participating centres in 84 countries prospectively collected data on all adult (>16 years) patients admitted to their ICU between May 8 and May 18, 2012, except those admitted for fewer than 24 h for routine postoperative monitoring. Participation was voluntary. Data were collected daily for a maximum of 28 days in the ICU and patients were followed up for outcome data until death or hospital discharge. In-hospital death was analysed using multilevel logistic regression with three levels: patient, hospital, and country. FINDINGS 10,069 patients were included from ICUs in Europe (5445 patients; 54·1%), Asia (1928; 19·2%), the Americas (1723; 17·1%), Oceania (439; 4·4%), the Middle East (393; 3·9%), and Africa (141; 1·4%). Overall, 2973 patients (29·5%) had sepsis on admission or during the ICU stay. ICU mortality rates were 16·2% (95% CI 15·5-16·9) across the whole population and 25·8% (24·2-27·4) in patients with sepsis. Hospital mortality rates were 22·4% (21·6-23·2) in the whole population and 35·3% (33·5-37·1) in patients with sepsis. Using a multilevel analysis, the unconditional model suggested significant between-country variations (var=0·19, p=0·002) and between-hospital variations (var=0·43, p<0·0001) in the individual risk of in-hospital death. There was a stepwise increase in the adjusted risk of in-hospital death according to decrease in global national income. INTERPRETATION This large database highlights that sepsis remains a major health problem worldwide, associated with high mortality rates in all countries. Our findings also show a significant association between the risk of death and the global national income and suggest that ICU organisation has an important effect on risk of death. FUNDING None.

Development and validation of PRE-DELIRIC (PREdiction of DELIRium in ICu patients) delirium prediction model for intensive care patients: observational multicentre study

Objectives To develop and validate a delirium prediction model for adult intensive care patients and determine its additional value compared with prediction by caregivers. Design Observational multicentre study. Setting Five intensive care units in the Netherlands (two university hospitals and three university affiliated teaching hospitals). Participants 3056 intensive care patients aged 18 years or over. Main outcome measure Development of delirium (defined as at least one positive delirium screening) during patients’ stay in intensive care. Results The model was developed using 1613 consecutive intensive care patients in one hospital and temporally validated using 549 patients from the same hospital. For external validation, data were collected from 894 patients in four other hospitals. The prediction (PRE-DELIRIC) model contains 10 risk factors—age, APACHE-II score, admission group, coma, infection, metabolic acidosis, use of sedatives and morphine, urea concentration, and urgent admission. The model had an area under the receiver operating characteristics curve of 0.87 (95% confidence interval 0.85 to 0.89) and 0.86 after bootstrapping. Temporal validation and external validation resulted in areas under the curve of 0.89 (0.86 to 0.92) and 0.84 (0.82 to 0.87). The pooled area under the receiver operating characteristics curve (n=3056) was 0.85 (0.84 to 0.87). The area under the curve for nurses’ and physicians’ predictions (n=124) was significantly lower at 0.59 (0.49 to 0.70) for both. Conclusion The PRE-DELIRIC model for intensive care patients consists of 10 risk factors that are readily available within 24 hours after intensive care admission and has a high predictive value. Clinical prediction by nurses and physicians performed significantly worse. The model allows for early prediction of delirium and initiation of preventive measures. Trial registration Clinical trials NCT00604773 (development study) and NCT00961389 (validation study).

Immunochemical and Mass-Spectrometry–Based Serum Hepcidin Assays for Iron Metabolism Disorders

BACKGROUND Hepcidin is an iron-regulatory peptide hormone that consists of 3 isoforms: bioactive hepcidin-25, and inactive hepcidin-22 and hepcidin-20. Hepcidin is instrumental in the diagnosis and monitoring of iron metabolism disorders, but reliable methods for its quantification in serum are sparse, as is knowledge of their relative analytical strengths and clinical utility. METHODS We developed a competitive (c)-ELISA and an immunocapture TOF mass-spectrometry (IC-TOF-MS) assay. Exploiting these 2 methods and our previously described weak cation exchange (WCX)-TOF-MS assay, we measured serum hepcidin concentrations in 186 patients with various disorders of iron metabolism and in 23 healthy controls. RESULTS We found that (a) the relative differences in median hepcidin concentrations in various diseases to be similar, although the absolute concentrations measured with c-ELISA and WCX-TOF-MS differed; (b) hepcidin isoforms contributed to differences in hepcidin concentrations between methods, which were most prominent in patients with chronic kidney disease; and (c) hepcidin concentrations measured by both the c-ELISA and IC-TOF-MS correlated with ferritin concentrations <60 μg/L, and were suitable for distinguishing between iron deficiency anemia (IDA) and the combination of IDA and anemia of chronic disease. CONCLUSIONS c-ELISA is the method of choice for the large-scale quantification of serum hepcidin concentrations, because of its low limit of detection, low cost, and high-throughput. Because of its specificity for bioactive hepcidin-25, WCX-TOF-MS can be regarded as a valuable special-purpose assay for disorders with variable concentrations of hepcidin isoforms, such as chronic kidney disease.

Delirium in critically ill patients: Impact on long-term health-related quality of life and cognitive functioning.

Objective:To examine the impact of delirium during intensive care unit stay on long-term health-related quality of life and cognitive function in intensive care unit survivors. Design:Prospective 18-month follow-up study. Setting:Four intensive care units of a university hospital. Patients:A median of 18 months after intensive care discharge, questionnaires were sent to 1,292 intensive care survivors with (n = 272) and without (n = 1020) delirium during their intensive care stay. Measurements and Main Results:The Short Form-36v1, checklist individual strength-fatigue, and cognitive failure questionnaire were used. Covariance analysis was performed to adjust for relevant covariates. Of the 915 responders, 171 patients were delirious during their intensive care stay (median age 65 [interquartile range 58–85], Acute Physiology and Chronic Health Evaluation II score 17 [interquartile range 14–20]), and 745 patients were not (median age 65 [interquartile range 57–72], Acute Physiology and Chronic Health Evaluation II score 13 [interquartile range 10–16]). After adjusting for covariates, no differences were found between delirium and nondelirium survivors on the Short Form-36 and checklist individual strength-fatigue. However, survivors who had suffered from delirium reported that they made significantly more social blunders, and their total cognitive failure questionnaire score was significantly higher, compared to survivors who had not been delirious. Survivors of a hypoactive delirium subtype performed significantly better on the domain mental health than mixed and hyperactive delirium patients. Duration of delirium was significantly correlated to problems with memory and names. Conclusions:Intensive care survivors with delirium during their intensive care unit stay had a similar adjusted health-related quality of life evaluation, but significantly more cognitive problems than those who did not suffer from delirium, even after adjusting for relevant covariates. In addition, the duration of delirium was related to long-term cognitive problems.

Gender differences in the innate immune response and vascular reactivity following the administration of endotoxin to human volunteers.

Objective:To determine gender differences in the innate immune response and vascular reactivity during human endotoxemia. Design:Clinical experimental study. Setting:University medical center intensive care research unit. Subjects:Fifteen female and 15 male volunteers. Interventions:Intravenous injection of 2 ng/kg Escherichia coli lipopolysaccharide. Measurements and Main Results:C-reactive protein, leukocytes, and cytokines were measured at regular time intervals as indicators of inflammation. Heart rate and blood pressure were continuously monitored. Forearm blood flow and the responsiveness of forearm vessels to the intrabrachial infusion of norepinephrine (1–3–10–30 ng/min/dL) were measured before and 4 hrs after the administration of endotoxin using venous occlusion plethysmography. Differences were tested with repeated-measures analysis of variance.Females showed a more proinflammatory response to lipopolysaccharide than males, illustrated by a higher rise in C-reactive protein (42 ± 3 vs. 29 ± 3 mg/L, p = .002) and more leukocyte sequestration (leukopenia 1.8 ± 0.1 × 109 vs. 2.4 ± 0.1 × 109, p = .003). The increase in cytokine levels showed a more proinflammatory pattern in females as reflected by a higher increase in tumor necrosis factor-&agr; (965 ± 193 vs. 411 ± 35 pg/mL, p < .0001), whereas the increase of the anti-inflammatory interleukin-10 was not significantly different (95 ± 15 pg/mL in females vs. 129 ± 15 pg/mL in males, p = .288). Females exhibited higher baseline levels (9.9 ± 1.1 vs. 7.0 ± 0.8 pg/mL in males, p = .042) and an augmented increase in lipopolysaccharide-binding protein, which may explain the more pronounced inflammatory response in females. The lipopolysaccharide-induced change in heart rate was not significantly different between the genders, whereas blood pressure decreased more in females (p < .0001). Lipopolysaccharide administration significantly attenuated the norepinephrine sensitivity in males (p = .002), whereas no lipopolysaccharide-induced effect was observed in females (p = .552; difference between groups, p = .045). Conclusions:During experimental human endotoxemia, females showed a more pronounced proinflammatory innate immune response associated with less attenuation of norepinephrine sensitivity. These findings may be relevant in view of the profound and incompletely explained differences in incidence and outcome of sepsis among male and female patients.

Functional heterogeneity and differential priming of circulating neutrophils in human experimental endotoxemia

Neutrophils play an important role in host defense. However, deregulation of neutrophils contributes to tissue damage in severe systemic inflammation. In contrast to complications mediated by an overactive neutrophil compartment, severe systemic inflammation is a risk factor for development of immune suppression and as a result, infectious complications. The role of neutrophils in this clinical paradox is poorly understood, and in this study, we tested whether this paradox could be explained by distinct neutrophil subsets and their functionality. We studied the circulating neutrophil compartment immediately after induction of systemic inflammation by administering 2 ng/kg Escherichia coli LPS i.v. to healthy volunteers. Neutrophils were phenotyped by expression of membrane receptors visualized by flow cytometry, capacity to interact with fluorescently labeled microbes, and activation of the NADPH‐oxidase by oxidation of Amplex Red and dihydrorhodamine. After induction of systemic inflammation, expression of membrane receptors on neutrophils, such as CXCR1 and ‐2 (IL‐8Rs), C5aR, FcγRII, and TLR4, was decreased. Neutrophils were also refractory to fMLF‐induced up‐regulation of membrane receptors, and suppression of antimicrobial function was shown by decreased interaction with Staphylococcus epidermis. Simultaneously, activation of circulating neutrophils was demonstrated by a threefold increase in release of ROS. The paradoxical phenotype can be explained by the selective priming of the respiratory burst. In contrast, newly released, CD16dim banded neutrophils display decreased antimicrobial function. We conclude that systemic inflammation leads to a functionally heterogeneous neutrophil compartment, in which newly released refractory neutrophils can cause susceptibility to infections, and activated, differentiated neutrophils can mediate tissue damage.

Alkaline phosphatase for treatment of sepsis-induced acute kidney injury: a prospective randomized double-blind placebo-controlled trial

IntroductionTo evaluate whether alkaline phosphatase (AP) treatment improves renal function in sepsis-induced acute kidney injury (AKI), a prospective, double-blind, randomized, placebo-controlled study in critically ill patients with severe sepsis or septic shock with evidence of AKI was performed.MethodsThirty-six adult patients with severe sepsis or septic shock according to Systemic Inflammatory Response Syndrome criteria and renal injury defined according to the AKI Network criteria were included. Dialysis intervention was standardized according to Acute Dialysis Quality Initiative consensus. Intravenous infusion of alkaline phosphatase (bolus injection of 67.5 U/kg body weight followed by continuous infusion of 132.5 U/kg/24 h for 48 hours, or placebo) starting within 48 hours of AKI onset and followed up to 28 days post-treatment. The primary outcome variable was progress in renal function variables (endogenous creatinine clearance, requirement and duration of renal replacement therapy, RRT) after 28 days. The secondary outcome variables included changes in circulating inflammatory mediators, urinary excretion of biomarkers of tubular injury, and safety.ResultsThere was a significant (P = 0.02) difference in favor of AP treatment relative to controls for the primary outcome variable. Individual renal parameters showed that endogenous creatinine clearance (baseline to Day 28) was significantly higher in the treated group relative to placebo (from 50 ± 27 to 108 ± 73 mL/minute (mean ± SEM) for the AP group; and from 40 ± 37 to 65 ± 30 mL/minute for placebo; P = 0.01). Reductions in RRT requirement and duration did not reach significance. The results in renal parameters were supported by significantly more pronounced reductions in the systemic markers C-reactive protein, Interleukin-6, LPS-binding protein and in the urinary excretion of Kidney Injury Molecule-1 and Interleukin-18 in AP-treated patients relative to placebo. The Drug Safety Monitoring Board did not raise any issues throughout the trial.ConclusionsThe improvements in renal function suggest alkaline phosphatase is a promising new treatment for patients with severe sepsis or septic shock with AKI.Trial Registrationwww.clinicaltrials.gov: NCTNCT00511186