Publications by authors named "Koopman A"

Electrical impedance tomography (EIT) is an emerging technology for the non-invasive monitoring of regional distribution of ventilation and perfusion, offering real-time and continuous data that can greatly enhance our understanding and management of various respiratory conditions and lung perfusion. Its application may be especially beneficial for critically ill mechanically ventilated patients. Despite its potential, clear evidence of clinical benefits is still lacking, in part due to a lack of standardization and transparent reporting, which is essential for ensuring reproducible research and enhancing the use of EIT for personalized mechanical ventilation.

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Tissue hydration provides articular cartilage with dynamic viscoelastic properties. Early stage osteoarthritis (OA) is marked by loss of proteoglycans and glycosaminoglycans (GAG), lowering fixed charge density, and impairing tissue osmotic function. The most common GAG replacement, chondroitin sulfate (CS), has failed to show effectiveness.

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Background: Lung volume optimization maneuvers (LVOM) are necessary to make physiologic use of high-frequency oscillatory ventilation (HFOV), but lung behavior during such maneuvers has not been studied to determine lung volume changes after initiation of HFOV, to quantify recruitment versus derecruitment during the LVOM and to calculate the time to stabilization after a pressure change.

Methods: We performed a secondary analysis of prospectively collected data in subjects < 18 years on HFOV. Uncalibrated respiratory inductance plethysmography (RIP) tracings were used to quantify lung recruitment and derecruitment during the LVOM inflation and deflation.

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Article Synopsis
  • Post-translational modifications (PTMs) are essential for the regulation of sarcomeric proteins, particularly myosins, which are key for muscle contraction and cell motility.
  • Myosin consists of two heavy chains and two pairs of light chains, with specific regions prone to PTMs that can influence their function.
  • Dysregulation of these PTMs can lead to muscle dysfunction and contribute to diseases like myopathies and cardiovascular disorders, making their study important for understanding muscle physiology.
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Background: The underlying pathophysiological pathways how reverse triggering is being caused are not fully understood. Respiratory entrainment may be one of these mechanisms, but both terms are used interchangeably. We sought to characterize reverse triggering and the relationship with respiratory entrainment among mechanically ventilated children with and without acute lung injury.

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Sleep is a complex physiological process with an important role in memory consolidation characterised by a series of spatiotemporal changes in brain activity and connectivity. Here, we investigate how task-related responses differ between pre-sleep wake, sleep, and post-sleep wake. To this end, we trained participants on a serial reaction time task using both right and left hands using Targeted Memory Reactivation (TMR), in which auditory cues are associated with learned material and then re-presented in subsequent wake or sleep periods in order to elicit memory reactivation.

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Background: Accuracy of esophageal pressure measured by an air-filled esophageal balloon catheter is dependent on balloon filling volume. However, this has been understudied in mechanically ventilated children. We sought to study the optimal filling volume in children receiving ventilation by using previously reported calibration methods.

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Surface electromyography (sEMG) can be used to measure the electrical activity of the respiratory muscles. The possible applications of sEMG span from patients suffering from acute respiratory failure to patients receiving chronic home mechanical ventilation, to evaluate muscle function, titrate ventilatory support and guide treatment. However, sEMG is mainly used as a monitoring tool for research and its use in clinical practice is still limited-in part due to a lack of standardization and transparent reporting.

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Objective: Ethnic minority groups have experienced a disproportionate burden of COVID-19, and should therefore be especially encouraged to receive SARS-CoV-2 vaccination. This study compared first-dose uptake of the primary SARS-CoV-2 vaccination series across six ethnic groups in Amsterdam, the Netherlands in 2021.

Methods: We analyzed data from participants of the population-based HELIUS cohort.

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It is now well established that memories can reactivate during non-rapid eye movement (non-REM) sleep, but the question of whether equivalent reactivation can be detected in rapid eye movement (REM) sleep is hotly debated. To examine this, we used a technique called targeted memory reactivation (TMR) in which sounds are paired with learned material in wake, and then re-presented in subsequent sleep, in this case REM, to trigger reactivation. We then used machine learning classifiers to identify reactivation of task-related motor imagery from wake in REM sleep.

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Introduction: It is currently unknown how the central nervous system controls ballistic whole-body movements like vertical jumps. Here we set out to study the time frame of generating muscle activation patterns for maximum-effort jumps from different initial postures.

Methods: We had ten healthy male participants make a slow countermovement from an upright position and initiate a maximal vertical jump as soon as possible following an auditory trigger.

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Background: The patient's neuro-respiratory drive, measured as electrical activity of the diaphragm (EAdi), quantifies the mechanical load on the respiratory muscles. It correlates with respiratory effort but requires a dedicated esophageal catheter. Transcutaneous (surface) monitoring of respiratory muscle electromyographic (sEMG) signals may be considered a suitable alternative to EAdi because of its non-invasive character, with the additional benefit that it allows for simultaneously monitoring of other respiratory muscles.

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Background: Ethnic minority groups experience a disproportionately high burden of infections, hospitalizations and mortality due to COVID-19, and therefore should be especially encouraged to receive SARS-CoV-2 vaccination. This study aimed to investigate the intent to vaccinate against SARS-CoV-2, along with its determinants, in six ethnic groups residing in Amsterdam, the Netherlands.

Methods: We analyzed data of participants enrolled in the population-based multi-ethnic HELIUS cohort, aged 24 to 79 years, who were tested for SARS-CoV-2 antibodies and answered questions on vaccination intent from November 23, 2020 to March 31, 2021.

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Targeted memory reactivation (TMR) is a technique in which sensory cues associated with memories during wake are used to trigger memory reactivation during subsequent sleep. The characteristics of such cued reactivation, and the optimal placement of TMR cues, remain to be determined. We built an EEG classification pipeline that discriminated reactivation of right- and left-handed movements and found that cues which fall on the up-going transition of the slow oscillation (SO) are more likely to elicit a classifiable reactivation.

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Article Synopsis
  • The study investigates the effectiveness of two ventilation methods, pressure controlled assist/control (PC-A/C) and continuous spontaneous ventilation (CSV), in weaning children under 5 years from ventilators due to respiratory failure.
  • Researchers measured patient effort using techniques like inspiratory work of breathing and pressure-rate-product in 36 children, finding no significant differences in effort between the two ventilation modes.
  • A reduction in pressure support during ventilation did lead to a significant increase in patient effort, although the changes were clinically noticeable rather than statistically significant.
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Objectives: It has been suggested that ethnic minorities have been disproportionally affected by the COVID-19. We aimed to determine whether prevalence and correlates of past SARS-CoV-2 exposure varied between six ethnic groups in Amsterdam, the Netherlands.

Design, Setting, Participants: Participants aged 25-79 years enrolled in the Healthy Life in an Urban Setting population-based prospective cohort (n=16 889) were randomly selected within ethnic groups and invited to participate in a cross-sectional COVID-19 seroprevalence substudy.

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Background: Allowing the ventilated adult patient to breathe spontaneously may improve tidal volume (V) distribution toward the dependent lung regions, reduce shunt fraction, and decrease dead space. It has not been studied if these effects under various levels of ventilatory support also occur in children. We sought to explore the effect of level of ventilatory support on V distribution and end-expiratory lung volume (EELV) in spontaneously breathing ventilated children in the recovery phase of their acute respiratory failure.

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Background: Surveillance data in high-income countries have reported more frequent SARS-CoV-2 diagnoses in ethnic minority groups. We examined the cumulative incidence of SARS-CoV-2 and its determinants in six ethnic groups in Amsterdam, the Netherlands.

Methods: We analysed participants enrolled in the population-based HELIUS cohort, who were tested for SARS-CoV-2-specific antibodies and answered COVID-19-related questions between June 24-October 9, 2020 (after the first wave) and November 23, 2020-March 31, 2021 (during the second wave).

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Objectives: Driving pressure (ratio of tidal volume over respiratory system compliance) is associated with mortality in acute respiratory distress syndrome. We sought to evaluate if such association could be identified in critically ill children.

Design: We studied the association between driving pressure on day 1 of mechanical ventilation and ventilator-free days at day 28 through secondary analyses of prospectively collected physiology data.

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Differences in glucose metabolism among categories of prediabetes have not been systematically investigated. In this longitudinal study, participants ( = 2,111) underwent a 2-h 75-g oral glucose tolerance test (OGTT) at baseline and 48 months. HbA was also measured.

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Aim: Subclasses of different glycaemic disturbances could explain the variation in characteristics of individuals with type 2 diabetes (T2D). We aimed to examine the association between subgroups based on their glucose curves during a five-point mixed-meal tolerance test (MMT) and metabolic traits at baseline and glycaemic deterioration in individuals with T2D.

Methods: The study included 787 individuals with newly diagnosed T2D from the Diabetes Research on Patient Stratification (IMI-DIRECT) Study.

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Background: Titration of the continuous distending pressure during a staircase incremental-decremental pressure lung volume optimization maneuver in children on high-frequency oscillatory ventilation is traditionally driven by oxygenation and hemodynamic responses, although validity of these metrics has not been confirmed.

Methods: Respiratory inductance plethysmography values were used construct pressure-volume loops during the lung volume optimization maneuver. The maneuver outcome was evaluated by three independent investigators and labeled positive if there was an increase in respiratory inductance plethysmography values at the end of the incremental phase.

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Background: Patient-ventilator asynchrony is associated with increased morbidity and mortality. A direct causative relationship between Patient-ventilator asynchrony and adverse clinical outcome have yet to be demonstrated. It is hypothesized that during trigger errors excessive pleural pressure swings are generated, contributing to increased work-of-breathing and self-inflicted lung injury.

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Aim: To examine the hypothesis that, based on their glucose curves during a seven-point oral glucose tolerance test, people at elevated type 2 diabetes risk can be divided into subgroups with different clinical profiles at baseline and different degrees of subsequent glycaemic deterioration.

Methods: We included 2126 participants at elevated type 2 diabetes risk from the Diabetes Research on Patient Stratification (IMI-DIRECT) study. Latent class trajectory analysis was used to identify subgroups from a seven-point oral glucose tolerance test at baseline and follow-up.

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Article Synopsis
  • The study investigates the relationship between mechanical energy (ME) delivered by ventilators and lung injury in mechanically ventilated children, focusing on how tidal volume normalized to body weight correlates with lung pathology.
  • Researchers analyzed data from 312 pediatric patients, finding that ME, rather than mechanical power (MP), was more strongly associated with underlying lung conditions and the duration of ventilation.
  • The results indicate that a significant portion of ventilator-generated energy is transferred to the lungs, influenced by factors like lung compliance and airway resistance.
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