Gert Jan Scheffer

Defining and Improving Data Quality in Medical Registries: A Literature Review, Case Study, and Generic Framework

Over the past years the number of medical registries has increased sharply. Their value strongly depends on the quality of the data contained in the registry. To optimize data quality, special procedures have to be followed. A literature review and a case study of data quality formed the basis for the development of a framework of procedures for data quality assurance in medical registries. Procedures in the framework have been divided into procedures for the co-ordinating center of the registry (central) and procedures for the centers where the data are collected (local). These central and local procedures are further subdivided into (a) the prevention of insufficient data quality, (b) the detection of imperfect data and their causes, and (c) actions to be taken / corrections. The framework can be used to set up a new registry or to identify procedures in existing registries that need adjustment to improve data quality.

Chronic post‐thoracotomy pain: a retrospective study

Background:  Chronic pain is common after thoracotomy. The primary goal of this study was to investigate the incidence of chronic post‐thoracotomy pain. The secondary goal was to identify possible risk factors associated with the development of chronic post‐operative pain.

Low-tidal-volume mechanical ventilation induces a toll-like receptor 4-dependent inflammatory response in healthy mice.

Background:Mechanical ventilation (MV) can induce ventilator-induced lung injury. A role for proinflammatory pathways has been proposed. The current studies analyzed the roles of Toll-like receptor (TLR) 4 and TLR2 involvement in the inflammatory response after MV in the healthy lung. Methods:Wild-type (WT) C57BL6, TLR4 knockout (KO), and TLR2 KO mice were mechanically ventilated for 4 h. Bronchoalveolar lavage fluid was analyzed for presence of endogenous ligands. Lung homogenates were used to investigate changes in TLR4 and TLR2 expression. Cytokines were measured in lung homogenate and plasma, and leukocytes were counted in lung tissue. Results:MV significantly increased endogenous ligands for TLR4 in bronchoalveolar lavage fluid and relative messenger RNA expression of TLR4 and TLR2 in lung tissue. In lung homogenates, MV in WT mice increased levels of keratinocyte-derived chemokine, interleukin (IL)-1α, and IL-1β. In TLR4 KO mice, MV increased IL-1α but not IL-1β, and the increase in keratinocyte-derived chemokine was less pronounced. In plasma, MV in WT mice increased levels of IL-6, keratinocyte-derived chemokine, and tumor necrosis factor α. In TLR4 KO mice, MV did not increase levels of IL-6 or tumor necrosis factor α, and the response of keratinocyte-derived chemokine was less pronounced. MV in TLR2 KO mice did not result in different cytokine levels compared with WT mice. In WT and TLR2 KO mice, but not in TLR4 KO mice, MV increased the number of pulmonary leukocytes. Conclusions:The current study supports a role for TLR4 in the inflammatory reaction after short-term MV in healthy lungs. Increasing the understanding of the innate immune response to MV may lead to future treatment advances in ventilator-induced lung injury, in which TLR4 may serve as a therapeutic target.

Mechanical ventilation in healthy mice induces reversible pulmonary and systemic cytokine elevation with preserved alveolar integrity : An in vivo model using clinical relevant ventilation settings

Background:Mechanical ventilation (MV) may activate the innate immune system, causing the release of cytokines. The resulting proinflammatory state is a risk factor for ventilator-induced lung injury. Cytokine increase results from direct cellular injury but may also result from cyclic stretch alone as demonstrated in vitro: mechanotransduction. To study mechanotransduction in vivo, the authors used an animal MV model with clinically relevant ventilator settings, avoiding alveolar damage. Methods:Healthy C57BL6 mice (n = 82) were ventilated (tidal volume, 8 ml/kg; positive end-expiratory pressure, 4 cm H2O; fraction of inspired oxygen, 0.4) for 30, 60, 120, and 240 min. Assigned animals were allowed to recover for 2 days after MV. Both pulmonary tissue and plasma interleukin (IL)-1&agr;, IL-1&bgr;, tumor necrosis factor &agr;, IL-6, IL-10, and keratinocyte-derived chemokine levels were measured. Histopathologic appearance of lung tissue was analyzed by light microscopy and electron microscopy. Results:In lung tissue, all measured cytokines and keratinocyte-derived chemokine levels increased progressively with MV duration. Light microscopy showed increased leukocyte influx but no signs of alveolar leakage or albumin deposition. Electron microscopy revealed intact epithelial cell and basement membranes with sporadically minimal signs of partial endothelial detachment. In plasma, increased levels of IL-1&agr;, tumor necrosis factor &agr;, IL-6, and keratinocyte-derived chemokine were measured after MV. In the recovery animals, cytokine levels had normalized and no histologic alterations could be found. Conclusions:Mechanical ventilation induces reversible cytokine increase and leukocyte influx with preserved tissue integrity. This model offers opportunities to study the pathophysiologic mechanisms behind ventilator-induced lung injury and the contribution of MV to the “multiple-hit” concept.

Systemic Inflammation Decreases Pain Threshold in Humans In Vivo

Background Hyperalgesia is a well recognized hallmark of disease. Pro-inflammatory cytokines have been suggested to be mainly responsible, but human data are scarce. Changes in pain threshold during systemic inflammation evoked by human endotoxemia, were evaluated with three quantitative sensory testing methods. Methods and Results Pressure pain thresholds, electrical pain thresholds and tolerance to the cold pressor test were measured before and 2 hours after the intravenous administration of 2 ng/kg purified E. coli endotoxin in 27 healthy volunteers. Another 20 subjects not exposed to endotoxemia served as controls. Endotoxemia led to a rise in body temperature and inflammatory symptom scores and a rise in plasma TNF-α, IL-6, IL-10 and IL-1RA. During endotoxemia, pressure pain thresholds and electrical pain thresholds were reduced with 20±4 % and 13±3 %, respectively. In controls only a minor decrease in pressure pain thresholds (7±3 %) and no change in electrical pain thresholds occurred. Endotoxin-treated subjects experienced more pain during the cold pressor test, and fewer subjects were able to complete the cold pressor test measurement, while in controls the cold pressor test results were not altered. Peak levels and area under curves of each individual cytokine did not correlate to a change in pain threshold measured by one of the applied quantitative sensory testing techniques. Conclusions and Significance In conclusion, this study shows that systemic inflammation elicited by the administration of endotoxin to humans, results in lowering of the pain threshold measured by 3 quantitative sensory testing techniques. The current work provides additional evidence that systemic inflammation is accompanied by changes in pain perception.

Toll-like Receptor 4 Signaling in Ventilator-induced Diaphragm Atrophy

Background: Mechanical ventilation induces diaphragm muscle atrophy, which plays a key role in difficult weaning from mechanical ventilation. The signaling pathways involved in ventilator-induced diaphragm atrophy are poorly understood. The current study investigated the role of Toll-like receptor 4 signaling in the development of ventilator-induced diaphragm atrophy. Methods: Unventilated animals were selected for control: wild-type (n = 6) and Toll-like receptor 4 deficient mice (n = 6). Mechanical ventilation (8 h): wild-type (n = 8) and Toll-like receptor 4 deficient (n = 7) mice. Myosin heavy chain content, proinflammatory cytokines, proteolytic activity of the ubiquitin-proteasome pathway, caspase-3 activity, and autophagy were measured in the diaphragm. Results: Mechanical ventilation reduced myosin content by approximately 50% in diaphragms of wild-type mice (P less than 0.05). In contrast, ventilation of Toll-like receptor 4 deficient mice did not significantly affect diaphragm myosin content. Likewise, mechanical ventilation significantly increased interleukin-6 and keratinocyte-derived chemokine in the diaphragm of wild-type mice, but not in ventilated Toll-like receptor 4 deficient mice. Mechanical ventilation increased diaphragmatic muscle atrophy factor box transcription in both wild-type and Toll-like receptor 4 deficient mice. Other components of the ubiquitin-proteasome pathway and caspase-3 activity were not affected by ventilation of either wild-type mice or Toll-like receptor 4 deficient mice. Mechanical ventilation induced autophagy in diaphragms of ventilated wild-type mice, but not Toll-like receptor 4 deficient mice. Conclusion: Toll-like receptor 4 signaling plays an important role in the development of ventilator-induced diaphragm atrophy, most likely through increased expression of cytokines and activation of lysosomal autophagy.

Emergence and Persistence of Macrolide Resistance in Oropharyngeal Flora and Elimination of Nasal Carriage of Staphylococcus aureus after Therapy with Slow-Release Clarithromycin: a Randomized, Double-Blind, Placebo-Controlled Study

ABSTRACT To investigate the effect of slow-release (SR) clarithromycin on colonization and the development of resistance in oropharyngeal and nasal flora, a double-blind, randomized, placebo-controlled trial was performed with 8 weeks of follow-up. A total of 296 patients with documented coronary artery disease were randomized in the preoperative outpatient clinic to receive a daily dose of SR clarithromycin (500 mg) (CL group) or placebo tablets (PB group) until the day of surgery. Nose and throat swabs were taken before the start of therapy, directly after the end of therapy, and 8 weeks later. The presence of potential pathogenic bacteria was determined, and if they were isolated, MIC testing was performed. Quantitative culture on media with and without macrolides was performed for the indigenous oropharyngeal flora. In addition, analysis of the mechanism of resistance was performed with the macrolide-resistant indigenous flora. Basic patient characteristics were comparable in the two treatment groups. The average number of tablets taken was 15 (standard deviation = 6.4). From the throat swabs, Haemophilus parainfluenzae was isolated and carriage was not affected in either of the treatment groups. Nasal carriage of Staphylococcus aureus, however, was significantly reduced in the CL group (from 35.3 to 4.3%) compared to the PB group (from 32.4 to 30.3%) (P < 0.0001; relative risk [RR], 7.0; 95% confidence interval [CI], 3.1 to 16.0). Resistance to clarithromycin was present significantly more frequently in H. parainfluenzae in the CL group after treatment (P = 0.007; RR, 1.6; 95% CI, 1.1 to 2.3); also, the percentage of patients with resistance to macrolides in the indigenous flora after treatment was significantly higher in the CL group (31 to 69%) (P < 0.0001; RR, 1.9; 95% CI, 1.4 to 2.5). This persisted for at least 8 weeks. This study shows that besides the effective elimination of nasal carriage of S. aureus, treatment with SR clarithromycin for approximately 2 weeks has a marked and sustained effect on the development of resistance in the oropharyngeal flora for at least 8 weeks.

The in vitro mechanisms and in vivo efficacy of intravenous lidocaine on the neuroinflammatory response in acute and chronic pain.

The neuroinflammatory response plays a key role in several pain syndromes. Intravenous (iv) lidocaine is beneficial in acute and chronic pain. This review delineates the current literature concerning in vitro mechanisms and in vivo efficacy of iv lidocaine on the neuroinflammatory response in acute and chronic pain.

DANGER IN THE INTENSIVE CARE UNIT: DAMPS IN CRITICALLY ILL PATIENTS

ABSTRACT Danger-associated molecular patterns (DAMPs) that are released by injured, threatened, or dead cells, or that originate from the extracellular matrix, influence the immune system. This is of great relevance in critically ill patients, in whom trauma or surgery-related cell damage, hypoxia, ischemia, and infections can result in extensive release of DAMPs. As many patients at the intensive care unit suffer from immune system-related complications, DAMPs could serve as markers for the prognosis of these patients and represent possible therapeutic targets. In the present review, we provide an overview of several well known DAMPs (high-mobility group box 1, heat-shock proteins, s100 proteins, nucleic acids, and hyaluronan) and their effects on the immune system. Furthermore, we discuss the role of DAMPs as markers or therapeutic targets in several conditions frequently encountered in critically ill patients, such as sepsis, trauma, ventilator-induced lung injury, and cardiac arrest.

Blueprints of signaling interactions between pattern recognition receptors: implications for the design of vaccine adjuvants.

ABSTRACT Innate immunity activation largely depends on recognition of microorganism structures by Pattern Recognition Receptors (PRRs). PRR downstream signaling results in production of pro- and anti-inflammatory cytokines and other mediators. Moreover, PRR engagement in antigen-presenting cells initiates the activation of adaptive immunity. Recent reports suggest that for the activation of innate immune responses and initiation of adaptive immunity, synergistic effects between two or more PRRs are necessary. No systematic analysis of the interaction between the major PRR pathways were performed to date. In this study, a systematical analysis of the interactions between PRR signaling pathways was performed. PBMCs derived from 10 healthy volunteers were stimulated with either a single PRR ligand or a combination of two PRR ligands. Known ligands for the major PRR families were used: Toll-like receptors (TLRs), C-type lectin receptors (CLRs), NOD-like receptors (NLRs), and RigI-helicases. After 24 h of incubation, production of tumor necrosis factor alpha (TNF-α), interleukin-1 beta (IL-1β), IL-6, and IL-10 was measured in supernatants by enzyme-linked immunosorbent assay (ELISA). The consistency of the PRR interactions (both inhibitory and synergistic) between the various individuals was assessed. A number of PRR-dependent signaling interactions were found to be consistent, both between individuals and with regard to multiple cytokines. The combinations of TLR2 and NOD2, TLR5 and NOD2, TLR5 and TLR3, and TLR5 and TLR9 acted as synergistic combinations. Surprisingly, inhibitory interactions between TLR4 and TLR2, TLR4 and Dectin-1, and TLR2 and TLR9 as well as TLR3 and TLR2 were observed. These consistent signaling interactions between PRR combinations may represent promising targets for immunomodulation and vaccine adjuvant development.