Alexander P. J. Vlaar

Dr. Alexander P. J. Vlaar

orcid

Research Focus & Metrics

Academic Career Length

20Years (2007-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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5 May 2020 in Journal of Thrombosis and Haemostasis
Verified
Journal Article
Open access
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SMSaskia Middeldorp
Saskia Middeldorp
MCMichiel Coppens
Michiel Coppens
THThijs F. van Haaps
Thijs F. van Haaps
MFMerijn Foppen
Merijn Foppen
AVAlexander P. J. Vlaar
Alexander P. J. Vlaar
NENick van Es
Nick van Es
Coronavirus disease 2019 (COVID‐19) can lead to systemic coagulation activation and thrombotic complications. We investigated the incidence of objectively confirmed venous thromboembolism (VTE) in 198 hospitalized patients with COVID‐19 in a single‐center cohort study. Seventy‐five patients (38%) were admitted to the intensive care unit (ICU). At time of data collection, 16 (8%) were still hospitalized and 19% had died. During a median follow‐up of 7 days (IQR, 3‐13), 39 patients (20%) were diagnosed with VTE of whom 25 (13%) had symptomatic VTE, despite routine thrombosis prophylaxis. The cumulative incidences of VTE at 7, 14 and 21 days were 16% (95% CI, 10‐22), 33% (95% CI, 23‐43) and 42% (95% CI 30‐54) respectively. For symptomatic VTE, these were 10% (95% CI, 5.8‐16), 21% (95% CI, 14‐30) and 25% (95% CI 16‐36). VTE appeared to be associated with death (adjusted HR, 2.4; 95% CI, 1.02‐5.5). The cumulative incidence of VTE was higher in the ICU (26% (95% CI, 17‐37), 47% (95% CI, 34‐58), and 59% (95% CI, 42‐72) at 7, 14 and 21 days) than on the wards (any VTE and symptomatic VTE 5.8% (95% CI, 1.4‐15), 9.2% (95% CI, 2.6‐21), and 9.2% (2.6‐21) at 7, 14, and 21 days). The observed risk for VTE in COVID‐19 is high, particularly in ICU patients, which should lead to a high level of clinical suspicion and low threshold for diagnostic imaging for DVT or PE. Future research should focus on optimal diagnostic and prophylactic strategies to prevent VTE and potentially improve survival.

17 March 2020 in JAMA
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Journal Article
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MWMarije Wijnberge
Marije Wijnberge
BGBart F. Geerts
Bart F. Geerts
LHLiselotte Hol
Liselotte Hol
NLNikki Lemmers
Nikki Lemmers
MMMarijn P. Mulder
Marijn P. Mulder
DVDenise P. Veelo
Denise P. Veelo
An estimated 266 million operations were performed worldwide in 2015.1 One of the risks patients commonly face is intraoperative hypotension. A previous study involving 255 patients reported that 87% experienced 1 or more hypotensive episodes intraoperatively (with hypotension defined as a mean arterial pressure [MAP] <65 mm Hg).2 Reported causes are anesthetic drugs, existing comorbidities, and surgical manipulation.3,4

26 January 2023 in New England Journal of Medicine
Verified
Journal Article
Closed access
MSMartje M. Suverein
Martje M. Suverein
TDThijs S.R. Delnoij
Thijs S.R. Delnoij
RLRoberto Lorusso
Roberto Lorusso
GBGeorge J. Brandon Bravo Bruinsma
George J. Brandon Bravo Bruinsma
LOLuuk Otterspoor
Luuk Otterspoor
MPMarcel C.G. van de Poll
Marcel C.G. van de Poll
Extracorporeal cardiopulmonary resuscitation (CPR) restores perfusion and oxygenation in a patient who does not have spontaneous circulation. The evidence with regard to the effect of extracorporeal CPR on survival with a favorable neurologic outcome in refractory out-of-hospital cardiac arrest is inconclusive. In this multicenter, randomized, controlled trial conducted in the Netherlands, we assigned patients with an out-of-hospital cardiac arrest to receive extracorporeal CPR or conventional CPR (standard advanced cardiac life support). Eligible patients were between 18 and 70 years of age, had received bystander CPR, had an initial ventricular arrhythmia, and did not have a return of spontaneous circulation within 15 minutes after CPR had been initiated. The primary outcome was survival with a favorable neurologic outcome, defined as a Cerebral Performance Category score of 1 or 2 (range, 1 to 5, with higher scores indicating more severe disability) at 30 days. Analyses were performed on an intention-to-treat basis. Of the 160 patients who underwent randomization, 70 were assigned to receive extracorporeal CPR and 64 to receive conventional CPR; 26 patients who did not meet the inclusion criteria at hospital admission were excluded. At 30 days, 14 patients (20%) in the extracorporeal-CPR group were alive with a favorable neurologic outcome, as compared with 10 patients (16%) in the conventional-CPR group (odds ratio, 1.4; 95% confidence interval, 0.5 to 3.5; P = 0.52). The number of serious adverse events per patient was similar in the two groups. In patients with refractory out-of-hospital cardiac arrest, extracorporeal CPR and conventional CPR had similar effects on survival with a favorable neurologic outcome. (Funded by the Netherlands Organization for Health Research and Development and Maquet Cardiopulmonary [Getinge]; INCEPTION ClinicalTrials.gov number, NCT03101787.).

7 January 2010 in Critical Care
Verified
Journal Article
Open access
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RDRogier M Determann
Rogier M Determann
ARAnnick Royakkers
Annick Royakkers
EWEsther K Wolthuis
Esther K Wolthuis
AVAlexander P. J. Vlaar
Alexander P. J. Vlaar
GCGoda Choi
Goda Choi
MSMarcus J Schultz
Marcus J Schultz
Introduction: Recent cohort studies have identified the use of large tidal volumes as a major risk factor for development of lung injury in mechanically ventilated patients without acute lung injury (ALI). We compared the effect of conventional with lower tidal volumes on pulmonary inflammation and development of lung injury in critically ill patients without ALI at the onset of mechanical ventilation. Methods: We performed a randomized controlled nonblinded preventive trial comparing mechanical ventilation with tidal volumes of 10 ml versus 6 ml per kilogram of predicted body weight in critically ill patients without ALI at the onset of mechanical ventilation. The primary end point was cytokine levels in bronchoalveolar lavage fluid and plasma during mechanical ventilation. The secondary end point was the development of lung injury, as determined by consensus criteria for ALI, duration of mechanical ventilation, and mortality. Results: One hundred fifty patients (74 conventional versus 76 lower tidal volume) were enrolled and analyzed. No differences were observed in lavage fluid cytokine levels at baseline between the randomization groups. Plasma interleukin-6 (IL-6) levels decreased significantly more strongly in the lower-tidal-volume group ((from 51 (20 to 182) ng/ml to 11 (5 to 20) ng/ml versus 50 (21 to 122) ng/ml to 21 (20 to 77) ng/ml; P = 0.01)). The trial was stopped prematurely for safety reasons because the development of lung injury was higher in the conventional tidal-volume group as compared with the lower tidal-volume group (13.5% versus 2.6%; P = 0.01). Univariate analysis showed statistical relations between baseline lung-injury score, randomization group, level of positive end-expiratory pressure (PEEP), the number of transfused blood products, the presence of a risk factor for ALI, and baseline IL-6 lavage fluid levels and the development of lung injury. Multivariate analysis revealed the randomization group and the level of PEEP as independent predictors of the development of lung injury. Conclusions: Mechanical ventilation with conventional tidal volumes is associated with sustained cytokine production, as measured in plasma. Our data suggest that mechanical ventilation with conventional tidal volumes contributes to the development of lung injury in patients without ALI at the onset of mechanical ventilation. Trial registration: ISRCTN82533884

26 February 2021 in Science
Verified
Journal Article
Open access
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MLMads Delbo Larsen
Mads Delbo Larsen
EGErik L. de Graaf
Erik L. de Graaf
MSMyrthe E. Sonneveld
Myrthe E. Sonneveld
HPH. Rosina Plomp
H. Rosina Plomp
JNJan Nouta
Jan Nouta
Gestur VidarssonGestur Vidarsson
Gestur Vidarsson
A single sugar makes all the difference: Antibodies are divided into several classes based on their nonvariable tail (Fc) domains. These regions interact with disparate immune cell receptors and complement proteins to help instruct distinct immune responses. The Fc domain of immunoglobulin G (IgG) antibodies contains a conserved N-linked glycan at position 297. However, the particular glycan used at this position is highly variable. IgG lacking core fucosylation at this position initiates enhanced antibody-dependent cellular cytotoxicity by increased affinity to the Fc receptor FcRIIIa. Larsen et al. report that COVID-19 patients with severe symptoms have increased levels of anti–severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) IgG afucosylation compared with patients with mild disease. These findings suggest that treatment of COVID-19 patients with fucosylated anti–SARS-CoV-2 antibodies may circumvent pathologies associated with severe COVID-19. Science , this issue p. eabc8378

2 June 2021 in Science Translational Medicine
Verified
Journal Article
Open access
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WHWillianne Hoepel
Willianne Hoepel
HCHung-Jen Chen
Hung-Jen Chen
CGChiara E. Geyer
Chiara E. Geyer
SASona Allahverdiyeva
Sona Allahverdiyeva
XMXue D. Manz
Xue D. Manz
JDJeroen den Dunnen
Jeroen den Dunnen
High titers and low fucosylation of human anti–spike protein IgG promote alveolar macrophage activation and inflammation.