Bleeding and thrombosis in intensive care patients with thrombocytopenia-Protocol for a topical systematic review

BACKGROUND

Thrombocytopenia is a common condition in critically ill patients in the intensive care unit (ICU). It is associated with prolonged stay in the ICU, increased transfusion requirements, risk of bleeding and mortality. The evidence regarding the use of prophylactic platelet transfusion and thrombosis prophylaxis in patients with thrombocytopenia in the ICU is unknown. To direct future research, we aim to assess the current evidence regarding prophylactic platelet transfusion and thrombosis prophylaxis on patient-important benefits and harms in the ICU population.

METHODS

We will conduct a topical systematic review of all study designs (ie no study design will per se be excluded from the proposed review) in accordance with the Preferred Reporting Items for Systematic and Meta-Analyses (PRISMA) statements. We will include studies on adult patients in the ICU where the incidence of thrombocytopenia and the predefined outcome measures, including mortality, quality-of-life, thrombotic events and haemorrhagic events are reported. We will provide descriptive analyses of the included studies/trials, ie no meta-analyses will be conducted, and the quality of evidence will be assessed according to the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

CONCLUSION

The outlined topical systematic review will provide important data on the benefits and harms of prophylactic platelet transfusion and thrombosis prophylaxis in ICU patients with thrombocytopenia and provide estimates on the rate of thrombocytopenia in this vulnerable population.

Coevolution of the coagulation and immune systems

BACKGROUND

Higher organisms rely on the coagulation and immune systems to fight disease-causing pathogens and other foreign invaders in the body. Coagulation has an important role as a barrier against foreign bodies, including bacteria, viruses, and protozoa. The protective responses associated with the coagulation and immune systems can protect the host organism from a wide range of pathogens, such as viruses, parasites, fungi, and even bacteria.

AIM

The purpose of this paper was to review available research on the evolution of the coagulation and immune systems.

MATERIALS AND METHODS

The study analyzed evidence from studies that have examined the coagulation and immune systems in the context of evolutionary processes. The articles used in the review were identified from the PsycINFO, CIHAHL, PubMed, Web of Science, and CIHAHL databases.

RESULTS

Studies have shown that both the coagulation system and the early immune system originated from the same initial system in early organisms. Some researchers argue that hemocytes from lower organisms are the common link from which the immune system and coagulation system developed.

DISCUSSION AND CONCLUSION

Simple organisms have hemocytes that can carry out both immune response and coagulation processes. Evolution led to the separation of these processes in higher organisms. Furthermore, this divergence resulted in the emergence of thrombocytes and plasmatic coagulation subsystems. These observations explain why there is some form of overlap between immunity and hemostasis, even in advanced organisms such as vertebrates. Several phenomena in clinical medicine related to coagulation and immunity can be explained by this overlap and are consistent with the hypothesis of the coevolution of coagulation and the immune system.

Thrombocytopenia in Intensive Care Unit

How to cite this article: Aluru N, Samavedam S. Thrombocytopenia in Intensive Care Unit. Indian J Crit Care Med 2019;23(Suppl 3):S185–S188.

Thrombocytopenia in the intensive care unit

Thrombocytopenia is a frequent finding in intensive care unit especially among adults and medical ICU patients. Thrombocytopenia is defined as a platelet count less than 100×10⁹/l in ICU setting. Platelets are made in the bone marrow from megakaryocytes. Although not fully understood, proplatelets transform into platelets in the lung. The body tries to maintain platelet count relatively constant throughout life. Pathophysiology of thrombocytopenia can be defined by hemodilution, elevated levels of platelet consumption, compromise of platelet production, increased platelet sequestration and increased platelet destruction. Unlike in other situations, absolute platelet count alone does not provide sufficient data in characterizing thrombocytopenia in ICU patients. In such cases, the time course of changes in platelet count is also pivotal. The dynamics of platelet count decrease vary considerably between different ICU patient populations including trauma, major surgery and minor surgery/medical conditions. There are strong evidences available that delay in platelet count restoration in ICU patients is an indicator of a bad outcome.

Immune Thrombocytopenia is Still the Commonest Diagnosis on Consultative Hematology

Thrombocytopenia is often a source of concern for physicians and patients alike and is one of the commonest reasons for a hematology consultation. Through this study, we wish to ascertain the different etiologies which should be kept in mind by a hematologist when a consultation for thrombocytopenia is sought. We assessed the etiology & clinical features of thrombocytopenia seen on consultative hematology calls for patients admitted in the general ward of a tertiary care hospital. 88/277 hematology consultations taken over a course of 2 months were for thrombocytopenia. The median age of these patients was 30 years, 62.5% were female, and median platelet of 40,500/µL (1000-112000). Mild, moderate & severe thrombocytopenia was seen in 6.8%, 27.3% and 65.9% respectively. 50% of patients had a primary hematological diagnosis. Immune thrombocytopenia (ITP) was the commonest diagnosis (38.6%). Bleeding manifestations were present in 48.9% patients with 20.5% having a major bleed. One third of hematology consultations in the general ward and emergency of a tertiary care hospital are for thrombocytopenia. Almost in half, the etiology of thrombocytopenia is related to a primary hematological disorder. This information should help in decision making of use of appropriate resources.

The primary haemostasis is more preserved in thrombocytopenic patients with liver cirrhosis than cancer

: In thrombocytopenia, differences in haemostatic capacity may explain discrepancies in bleeding risk between patients with cancer and patients with liver cirrhosis. The objective was to compare the haemostatic capacity in different thrombocytopenic patient populations. We evaluated platelet aggregation using impedance aggregometry (Multiplate Analyzer), von Willebrand factor antigen (VWF:Ag), VWF:ristocetin-cofactor activity (VWF:RCo), activated partial thromboplastin time (aPTT), coagulation factor VIII, fibrinogen, and thrombin generation in adult hospitalized patients with platelet count less than 80 × 10/l. Patients either had liver cirrhosis (n = 28), or cancer (n = 169; n = 49 had haematological cancer) with no difference among patients with liver cirrhosis and cancer. Median platelet count was 48 × 10/l [interquartile range (IQR) 32-63 × 10/l]. Median platelet aggregation was higher in patients with cirrhosis than cancer, 416 AU × min (IQR 257-676) versus 145 AU × min (IQR 50-326) for collagen-induced platelet aggregation, P < 0.001. There was no difference in activated partial thromboplastin time (aPTT), coagulation factor VIII, or thrombin generation between the patient groups. Fibrinogen activity was higher in patients with cancer compared with patients with cirrhosis [12.5 μmol/L (IQR 9.9-16.5) versus 7.2 μmol/l (IQR 5.6-10.2)], P < 0.003. Patients with liver cirrhosis had a more preserved primary haemostasis compared with patients with cancer.

Prophylactic platelet transfusions prior to surgery for people with a low platelet count

BACKGROUND

People with thrombocytopenia often require a surgical procedure. A low platelet count is a relative contraindication to surgery due to the risk of bleeding. Platelet transfusions are used in clinical practice to prevent and treat bleeding in people with thrombocytopenia. Current practice in many countries is to correct thrombocytopenia with platelet transfusions prior to surgery. Alternatives to platelet transfusion are also used prior surgery.

OBJECTIVES

To determine the clinical effectiveness and safety of prophylactic platelet transfusions prior to surgery for people with a low platelet count.

SEARCH METHODS

We searched the following major data bases: Cochrane Central Register of Controlled Trials (CENTRAL; 2017, Issue 2), PubMed (e-publications only), Ovid MEDLINE, Ovid Embase, the Transfusion Evidence Library and ongoing trial databases to 11 December 2017.

SELECTION CRITERIA

We included all randomised controlled trials (RCTs), as well as non-RCTs and controlled before-and-after studies (CBAs), that met Cochrane EPOC (Effective Practice and Organisation of Care) criteria, that involved the transfusion of platelets prior to surgery (any dose, at any time, single or multiple) in people with low platelet counts. We excluded studies on people with a low platelet count who were actively bleeding.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane for data collection. We were only able to combine data for two outcomes and we presented the rest of the findings in a narrative form.

MAIN RESULTS

We identified five RCTs, all conducted in adults; there were no eligible non-randomised studies. Three completed trials enrolled 180 adults and two ongoing trials aim to include 627 participants. The completed trials were conducted between 2005 and 2009. The two ongoing trials are scheduled to complete recruitment by October 2019. One trial compared prophylactic platelet transfusions to no transfusion in people with thrombocytopenia in an intensive care unit (ICU). Two small trials, 108 participants, compared prophylactic platelet transfusions to other alternative treatments in people with liver disease. One trial compared desmopressin to fresh frozen plasma or one unit of platelet transfusion or both prior to surgery. The second trial compared platelet transfusion prior to surgery with two types of thrombopoietin mimetics: romiplostim and eltrombopag. None of the included trials were free from methodological bias. No included trials compared different platelet count thresholds for administering a prophylactic platelet transfusion prior to surgery. None of the included trials reported on all the review outcomes and the overall quality per reported outcome was very low.None of the three completed trials reported: all-cause mortality at 90 days post surgery; mortality secondary to bleeding, thromboembolism or infection; number of red cell or platelet transfusions per participant; length of hospital stay; or quality of life.None of the trials included children or people who needed major surgery or emergency surgical procedures.Platelet transfusion versus no platelet transfusion (1 trial, 72 participants)We were very uncertain whether giving a platelet transfusion prior to surgery had any effect on all-cause mortality within 30 days (1 trial, 72 participants; risk ratio (RR) 0.78, 95% confidence interval (CI) 0.41 to 1.45; very-low quality evidence). We were very uncertain whether giving a platelet transfusion prior to surgery had any effect on the risk of major (1 trial, 64 participants; RR 1.60, 95% CI 0.29 to 8.92; very low-quality evidence), or minor bleeding (1 trial, 64 participants; RR 1.29, 95% CI 0.90 to 1.85; very-low quality evidence). No serious adverse events occurred in either study arm (1 trial, 72 participants, very low-quality evidence).Platelet transfusion versus alternative to platelet transfusion (2 trials, 108 participants)We were very uncertain whether giving a platelet transfusion prior to surgery compared to an alternative has any effect on the risk of major (2 trials, 108 participants; no events; very low-quality evidence), or minor bleeding (desmopressin: 1 trial, 36 participants; RR 0.89, 95% CI 0.06 to 13.23; very-low quality evidence: thrombopoietin mimetics: 1 trial, 65 participants; no events; very-low quality evidence). We were very uncertain whether there was a difference in transfusion-related adverse effects between the platelet transfused group and the alternative treatment group (desmopressin: 1 trial, 36 participants; RR 2.70, 95% CI 0.12 to 62.17; very-low quality evidence).

AUTHORS' CONCLUSIONS

Findings of this review were based on three small trials involving minor surgery in adults with thrombocytopenia. We found insufficient evidence to recommend the administration of preprocedure prophylactic platelet transfusions in this situation with a lack of evidence that transfusion resulted in a reduction in postoperative bleeding or all-cause mortality. The small number of trials meeting the inclusion criteria and the limitation in reported outcomes across the trials precluded meta-analysis for most outcomes. Further adequately powered trials, in people of all ages, of prophylactic platelet transfusions compared with no transfusion, other alternative treatments, and considering different platelet thresholds prior to planned and emergency surgical procedures are required. Future trials should include major surgery and report on bleeding, adverse effects, mortality (as a long-term outcome) after surgery, duration of hospital stay and quality of life measures.

Characterization of hospitalized cardiovascular patients with suspected heparin-induced thrombocytopenia

BACKGROUND

Little is known about heparin-induced thrombocytopenia (HIT), a pro-thrombotic, potentially life-threatening immune-mediated reaction to heparin exposure, in conservative and interventional cardiovascular medicine.

HYPOTHESIS

The 4T score, validated for prediction of HIT in surgical patients before, is also suitable for assessing HIT probability in cardiovascular patients with unclear thrombocytopenia.

METHODS

A total of 403 consecutive patients from our Department of Cardiology, Angiology and Pneumology in whom a HIT screening test was performed between 2009 and 2016 were identified. All 72 patients with a positive screening test were subjected to a functional confirmation test (heparin-induced platelet activation test, HIPA), resulting in 23 patients with serologically confirmed HIT (positive screening test, positive HIPA) and 49 patients with nonconfirmed HIT (positive screening test, negative HIPA).

RESULTS

The 4TScore had a sensitivity of 82.6% and a specificity of 28.6% in our patients, suggesting that it might not sufficiently predict the clinical probability of HIT in cardiovascular patients. In both confirmed and nonconfirmed HIT, intrahospital mortality was high without a significant difference (30% in confirmed HIT vs 43% in nonconfirmed HIT). Bacteremia was more often found in patients with nonconfirmed HIT, suggesting infection as a frequent differential diagnosis of thrombocytopenia in these patients (49% vs 17%, P = 0.0185).

CONCLUSION

HIT screening should be initiated in cardiovascular patients with unclear thrombocytopenia despite a low 4Tscore in order to distinguish patients requiring alternative anticoagulants from those with other causes such as infections. Further research is needed to specify the risk profile for HIT in cardiovascular patients.

Amicus or Adversary Revisited: Platelets in Acute Lung Injury and Acute Respiratory Distress Syndrome

Platelets are essential cellular effectors of hemostasis and contribute to disease as circulating effectors of pathologic thrombosis. These are their most widely known biologic activities. Nevertheless, recent observations demonstrate that platelets have a much more intricate repertoire beyond these traditional functions and that they are specialized for contributions to vascular barrier integrity, organ repair, antimicrobial host defense, inflammation, and activities across the immune continuum. Paradoxically, on the basis of clinical investigations and animal models of disease, some of these newly discovered activities of platelets appear to contribute to tissue injury. Studies in the last decade indicate unique interactions of platelets and their precursor, the megakaryocyte, in the lung and implicate platelets as essential effectors in experimental acute lung injury and clinical acute respiratory distress syndrome. Additional discoveries derived from evolving work will be required to precisely define the contributions of platelets to complex subphenotypes of acute lung injury and to determine if these remarkable and versatile blood cells are therapeutic targets in acute respiratory distress syndrome.

Evaluation of Thrombocytopenia in Critically Ill Patients Receiving Continuous Renal Replacement Therapy

BACKGROUND

Continuous renal replacement therapy (CRRT) may be associated with thrombocytopenia in critically ill patients. A confounding factor is concomitant use of unfractionated heparin (UFH) and suspicion for heparin-induced thrombocytopenia (HIT).

OBJECTIVE

To determine the impact of CRRT on platelet count and development of thrombocytopenia.

METHODS

Retrospective analyses evaluated the intrapatient change in platelet count following CRRT initiation. Critically ill adult patients who received CRRT for at least 48 hours were included. The primary outcome was intrapatient change in platelet count from CRRT initiation through the first 5 days of therapy. Secondary outcomes included thrombocytopenia incidence, identification of concomitant factors associated with thrombocytopenia, and frequency of HIT.

RESULTS

80 patients were included. Median platelet count at CRRT initiation (D0) was 128000/µL (81500-212500/µL), which was higher than those on subsequent post-CRRT days (D1: 104500/µL [63000-166750/µL]; D2: 88500/µL [53500-136750/µL]; D3: 91000/µL [49000-138000/µL]; D4: 93000/µL [46000-134000/µL]; and D5: 76000/µL [45500-151000/µL]; P < 0.05 for all). Twenty-five (35%) patients had thrombocytopenia on CRRT D0 compared with D2 (56.3%), D3 (58.7%), and D5 (59.1%); P < 0.05 for all. Controlling for potential confounders, Sequential Organ Failure Assessment score at the time of CRRT initiation was the only independent factor associated with thrombocytopenia. One (1.3%) patient had confirmed HIT. Conclusion and Relevance: This study is the first to demonstrate serial decreases in platelet count across multiple days after CRRT initiation. These data may provide additional insight to thrombocytopenia development in critically ill patients receiving heparin while on CRRT that is not associated with HIT.

The Impact of Nutritional Status and Complete Blood Count Parameters on Clinical Outcome in Geriatric Critically Ill Patients

Background

The geriatric population in intensive care units (ICUs) has recently increased. The aim of this study was to analyse the impact of initial complete blood count (CBC)-related parameters and nutritional status on morbidity and mortality in geriatric ICU patients.

Methods

A retrospective analysis was made of geriatric patients admitted to our tertiary adult ICU for 1 year. Patients with a length of stay (LOS) of < 48 h, with hematological malignancy or age < 65 years age were excluded from the study. Initial albumin level was considered to reflect nutritional status. The prevelance and risk factors of mortality and microbiologically documented infection (MDI) were analysed.

Results

The study included a total of 243 patients with a mean age of 78.96 ± 6.62 years. The overall mortality rate was 40.7%. The most common cause for admission was acute respiratory failure and sepsis (17.2% vs. 16.8%). The most common MDI sources were lower respiratory tract, bloodstream, and urinary tract infections. Patients with thrombocytopenia on admission had a higher mortality rate than patients with normal platelet count (P = 0.019). The initial albumin level of non-survivors was significantly lower than that of survivors (P = 0.001). There was a significant negative correlation between albumin level and LOS (r = -0.157; P = 0.000). Patients with hypoalbuminemia (albumin < 3.2 g/dL) at the time of diagnosis had higher mortality, LOS and MDI rates than those with normal albumin levels (P < 0.05). There was no significant relationship between any other CBC-related parameter and infection and mortality (P > 0.05).

Conclusions

Thrombocytopenia and hypoalbuminemia may be considered as major risk factors for morbidity and mortality in critically ill elderly patients.

Use of platelet transfusions prior to lumbar punctures or epidural anaesthesia for the prevention of complications in people with thrombocytopenia

BACKGROUND

People with a low platelet count (thrombocytopenia) often require lumbar punctures or an epidural anaesthetic. Lumbar punctures can be diagnostic (haematological malignancies, subarachnoid haematoma, meningitis) or therapeutic (spinal anaesthetic, administration of chemotherapy). Epidural catheters are placed for administration of epidural anaesthetic. Current practice in many countries is to correct thrombocytopenia with platelet transfusions prior to lumbar punctures and epidural anaesthesia, in order to mitigate the risk of serious procedure-related bleeding. However, the platelet count threshold recommended prior to these procedures varies significantly from country to country. This indicates significant uncertainty among clinicians regarding the correct management of these patients. The risk of bleeding appears to be low, but if bleeding occurs it can be very serious (spinal haematoma). Consequently, people may be exposed to the risks of a platelet transfusion without any obvious clinical benefit.This is an update of a Cochrane Review first published in 2016.

OBJECTIVES

To assess the effects of different platelet transfusion thresholds prior to a lumbar puncture or epidural anaesthesia in people with thrombocytopenia (low platelet count).

SEARCH METHODS

We searched for randomised controlled trials (RCTs), non-randomised controlled trials (nRCTs), controlled before-after studies (CBAs), interrupted time series studies (ITSs), and cohort studies in CENTRAL (the Cochrane Library 2018, Issue 1), MEDLINE (from 1946), Embase (from 1974), the Transfusion Evidence Library (from 1950), and ongoing trial databases to 13 February 2018.

SELECTION CRITERIA

We included RCTs, nRCTs, CBAs, ITSs, and cohort studies involving transfusions of platelet concentrates, prepared either from individual units of whole blood or by apheresis, and given to prevent bleeding in people of any age with thrombocytopenia requiring insertion of a lumbar puncture needle or epidural catheter.The original review only included RCTs.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane for including RCTs, nRCTs, CBAs, and ITSs. Two review authors independently assessed studies for eligibility and risk of bias and extracted data. Results were only expressed narratively.

MAIN RESULTS

We identified no completed or ongoing RCTs, nRCTs, CBAs, or ITSs. No studies included people undergoing an epidural procedure. No studies compared different platelet count thresholds prior to a procedure.In this update we identified three retrospective cohort studies that contained participants who did and did not receive platelet transfusions prior to lumbar puncture procedures. All three studies were carried out in people with cancer, most of whom had a haematological malignancy. Two studies were in children, and one was in adults.The number of participants receiving platelet transfusions prior to the lumbar puncture procedures was not reported in one study. We therefore only summarised in a narrative form the relevant outcomes from two studies (150 participants; 129 children and 21 adults), in which the number of participants who received the transfusion was given.We judged the overall risk of bias for all reported outcomes for both studies as 'serious' based on the ROBINS-I tool.No procedure-related major bleeding occurred in the two studies that reported this outcome (2 studies, 150 participants, no cases, very low-quality evidence).There was no evidence of a difference in the risk of minor bleeding (traumatic tap) in participants who received platelet transfusions before a lumbar puncture and those who did not receive a platelet transfusion before the procedure (2 studies, 150 participants, very low-quality evidence). One of the 14 adults who received a platelet transfusion experienced minor bleeding (traumatic tap; defined as at least 500 x 10⁶/L red blood cells in the cerebrospinal fluid); none of the seven adults who did not receive a platelet transfusion experienced this event. Ten children experienced minor bleeding (traumatic taps; defined as at least 100 x 10⁶/L red blood cells in the cerebrospinal fluid), six out of the 57 children who received a platelet transfusion and four out of the 72 children who did not receive a platelet transfusion.No serious adverse events occurred in the one study that reported this outcome (1 study, 21 participants, very low-quality evidence).We found no studies that evaluated all-cause mortality within 30 days from the lumbar puncture procedure, length of hospital stay, proportion of participants who received platelet transfusions, or quality of life.

AUTHORS' CONCLUSIONS

We found no evidence from RCTs or non-randomised studies on which to base an assessment of the correct platelet transfusion threshold prior to insertion of a lumbar puncture needle or epidural catheter. There are no ongoing registered RCTs assessing the effects of different platelet transfusion thresholds prior to the insertion of a lumbar puncture or epidural anaesthesia in people with thrombocytopenia. Any future study would need to be very large to detect a difference in the risk of bleeding. A study would need to be designed with at least 47,030 participants to be able to detect an increase in the number of people who had major procedure-related bleeding from 1 in 1000 to 2 in 1000. The use of a central data collection register or routinely collected electronic records (big data) is likely to be the only method to systematically gather data relevant to this population.

My patient is thrombocytopenic! Is (s)he? Why? And what shall I do?

Solving the riddle of a thrombocytopenic patient is a difficult and fascinating task. The spectrum of possible aetiologies is wide, ranging from an in vitro artefact to severe treatment-resistant thrombocytopenic bleeding conditions, or even life-threatening prothrombotic states. Moreover, thrombocytopenia by itself does not protect from thrombosis and sometimes a patient with a low platelet count requires concomitant antithrombotic treatment as well. In order to identify and treat the cause and the effects of the thrombocytopenia, you have to put together several pieces of information, solving a unique jig-jaw puzzle.

The present work is not a textbook article about thrombocytopenia, rather a collection of differential diagnostic thoughts, treatment concepts, and some basic knowledge, that you can retrieve when facing your next thrombocytopenic patient. Enjoy reading it, but most importantly enjoy taking care of patients with a low platelet count. I bet the present work will assist you in this challenging and rewarding clinical task.

Prognosis of Acute Respiratory Distress Syndrome in Patients With Hematological Malignancies

INTRODUCTION

The intensive care unit (ICU) admission of patients with hematologic malignancies is gradually increasing. Life-threatening events are common, and acute respiratory distress syndrome (ARDS) is one of the most critical conditions. The aim of this study was to investigate the clinical characteristics and outcomes of ARDS in patients with hematological malignancies admitted to the ICU.

METHODS

A retrospective study was performed on all patients with ARDS with hematological malignancies in a single tertiary teaching hospital between 2008 and 2015. Data on the treatment of and the outcomes of ARDS were collected to determine the clinical characteristics associated with ICU mortality.

RESULTS

During the 8-year study period, among a total of 821 patients with ARDS admitted to the ICU, all 185 patients with hematological malignancies were included in the analysis. Most of the patients (88.1%) had moderate-to-severe ARDS, and the median PaO₂/FiO₂ ratio was 122 (interquartile range: 88-157). The overall ICU mortality rate was 57.3% (50.0% for mild, 52.0% for moderate, and 67.7% for severe ARDS). After the univariate and the multivariate logistic regressions, the factors independently associated with a higher ICU mortality were severe ARDS (odds ratio [OR]: 2.47; 95% confidence interval [CI]: 1.17-5.25), identification of carbapenem-resistant gram-negative bacteria (OR: 6.61; 95% CI: 1.31-33.41), the amount of blood product transfusion (OR: 1.25; 95% CI: 1.13-1.38), and the progressive or refractory disease (OR: 3.01; 95% CI: 1.31-6.91). Mortality was independently lower in patients who received the initial low tidal volume ventilation (OR: 0.37, 95% CI: 0.14-0.96).

CONCLUSION

The outcome of ARDS in patients with hematological malignancies is associated with the severity of the underlying diseases, the presence of multidrug-resistance pathogens, and the amount of transfusion; however, strict application of low tidal volume ventilation may improve the outcome of these patients at the time of diagnosis.

Assessing thrombocytopenia in the intensive care unit: the past, present, and future

Thrombocytopenia is common among patients admitted to the intensive care unit (ICU). Multiple pathophysiological mechanisms may contribute, including thrombin-mediated platelet activation, dilution, hemophagocytosis, extracellular histones, ADAMTS13 deficiency, and complement activation. From the clinical perspective, the development of thrombocytopenia in the ICU usually indicates serious organ system derangement and physiologic decompensation rather than a primary hematologic disorder. Thrombocytopenia is associated with bleeding, transfusion, and adverse clinical outcomes including death, though few deaths are directly attributable to bleeding. The assessment of thrombocytopenia begins by looking back to the patient's medical history and presenting illness. This past information, combined with careful observation of the platelet trajectory in the context of the patient's clinical course, offers clues to the diagnosis and prognosis. Management is primarily directed at the underlying disorder and transfusion of platelets to prevent or treat clinical bleeding. Optimal platelet transfusion strategies are not defined, and a conservative approach is recommended.

Blood platelets and sepsis pathophysiology: A new therapeutic prospect in critically [corrected] ill patients?

Beyond haemostasis, platelets have emerged as versatile effectors of the immune response. The contribution of platelets in inflammation, tissue integrity and defence against infections has considerably widened the spectrum of their role in health and disease. Here, we propose a narrative review that first describes these new platelet attributes. We then examine their relevance to microcirculatory alterations in multi-organ dysfunction, a major sepsis complication. Rapid progresses that are made on the knowledge of novel platelet functions should improve the understanding of thrombocytopenia, a common condition and a predictor of adverse outcome in sepsis, and may provide potential avenues for management and therapy.

Platelet Counts and Postoperative Stroke After Coronary Artery Bypass Grafting Surgery

BACKGROUND

Declining platelet counts may reveal platelet activation and aggregation in a postoperative prothrombotic state. Therefore, we hypothesized that nadir platelet counts after on-pump coronary artery bypass grafting (CABG) surgery are associated with stroke.

METHODS

We evaluated 6130 adult CABG surgery patients. Postoperative platelet counts were evaluated as continuous and categorical (mild versus moderate to severe) predictors of stroke. Extended Cox proportional hazard regression analysis with a time-varying covariate for daily minimum postoperative platelet count assessed the association of day-to-day variations in postoperative platelet count with time to stroke. Competing risks proportional hazard regression models examined associations between day-to-day variations in postoperative platelet counts with timing of stroke (early: 0-1 days; delayed: ≥2 days).

RESULTS

Median (interquartile range) postoperative nadir platelet counts were 123.0 (98.0-155.0) × 10/L. The incidences of postoperative stroke were 1.09%, 1.50%, and 3.02% for platelet counts >150 × 10/L, 100 to 150 × 10/L, and <100 × 10/L, respectively. The risk for stroke increased by 12% on a given postoperative day for every 30 × 10/L decrease in platelet counts (adjusted hazard ratio [HR], 1.12; 95% confidence interval [CI], 1.01-1.24; P= .0255). On a given day, patients with moderate to severe thrombocytopenia were almost twice as likely to develop stroke (adjusted HR, 1.89; 95% CI, 1.13-3.16; P= .0155) as patients with nadir platelet counts >150 × 10/L. Importantly, such thrombocytopenia, defined as a time-varying covariate, was significantly associated with delayed (≥2 days after surgery; adjusted HR, 2.83; 95% CI, 1.48-5.41; P= .0017) but not early postoperative stroke.

CONCLUSIONS

Our findings suggest an independent association between moderate to severe postoperative thrombocytopenia and postoperative stroke, and timing of stroke after CABG surgery.

Prophylactic platelet transfusions prior to surgery for people with a low platelet count

This is a protocol for a Cochrane Review (Intervention). The objectives are as follows: To determine the clinical effectiveness and safety of prophylactic platelet transfusions prior to surgery for people with a low platelet count or platelet dysfunction (inherited or acquired).

Risk factors of mortality in bloodstream infections caused by Klebsiella pneumonia: A single-center retrospective study in China

The prevalence of Klebsiella pneumonia bloodstream infections (KP-BSIs) is increasing worldwide. Few study reports focus on the KP-BSIs published in Mainland China over the previous years. This study aimed to describe the risk factors of mortality from KP-BSIs.A retrospective study was conducted in a teaching hospital in Shanghai, China, for a period of 4 years. Risk factors related to the patient mortality were analyzed using the binary logistic regression model.Of 104 patients with KP-BSIs, the overall 30-day mortality rate was 25%. The logistic regression analysis revealed that thrombocytopenia (TB) (odds ratio [OR]: 1.007, 95% confidence interval [CI]: 1.002-1.013), pancreaticobiliary tract (PBT) (OR: 4.059, 95% CI: 1.398-11.78), and intra-abdominal infection (OR: 6.816, 95% CI: 1.806-25.716) were powerful risk factors leading to the mortality associated with KP-BSIs. Although prior antibiotic exposure, inappropriate empirical antibiotics, and inappropriate definitive antibiotics were not associated with mortality, multidrug-resistant (MDR) of KP-BSIs in the present study was high in both survivors and nonsurvivors (67.9% and 88.5%, respectively).TB, PBT, and intra-abdominal infection caused significant mortality rates increase in KP-BSIs during the study period.

Implementation of a rapid HIT immunoassay at a university hospital - Retrospective analysis of HIT laboratory orders in patients with thrombocytopenia

BACKGROUND

Heparin-induced thrombocytopenia (HIT) is a rare cause of thrombocytopenia and a potentially life-threatening adverse drug reaction. Clinical overdiagnosis of HIT results in costly laboratory tests and anticoagulation. Criteria and algorithms for diagnosis are established, but their translation into clinical practice is still challenging.

STUDY DESIGN AND METHODS

In a retrospective approach we studied all HIT related laboratory test requests within four years and evaluated data before (1st period, 24month) and after (2nd period, 24month) replacing particle gel immunoassay (PaGIA) and enzyme-linked immunosorbent assay (ELISA) by a chemiluminescent immunoassay (CLIA). HIT was confirmed by heparin-induced platelet activation (HIPA) test. Clinical pretest probability for HIT using an implemented simplified 4Ts score and platelet count were evaluated. Costs for laboratory tests and alternative anticoagulation were calculated.

RESULTS

In 1850 patients with suspected HIT, 2327 laboratory orders were performed. In 87.2% of these orders an intermediate/high simplified 4Ts score was found. Thrombocytopenia was present in 87.1%. After replacing PaGIA and ELISA by CLIA the number of immunological and functional laboratory tests was reduced by 38.2%. The number of positive HIT immunoassays declined from 22.6% to 6.0%, while the number of positive HIPA tests among positive immunological tests increased by 19%. Altogether, acute HIT was confirmed in 59 patients. A decline in the use of alternative anticoagulants was observed in the 2nd period.

CONCLUSION

Our study shows that in a university hospital setting HIT is well-known, but diagnosis requires a precise laboratory confirmation. Replacing PaGIA and ELISA by CLIA did not influence laboratory order behavior but results in reduced overall costs for laboratory diagnostics and alternative anticoagulation.

The Clinical Utility of the Heparin Neutralization Assay in the Diagnosis of Heparin-Induced Thrombocytopenia

Heparin-induced thrombocytopenia (HIT) remains diagnostically challenging. Immunoassays including PF4/heparin enzyme-linked immunosorbent assay (ELISA) have high sensitivity but low specificity. Whether the heparin neutralization assay (HNA) improves the diagnostic accuracy of the PF4/heparin ELISA for HIT is uncertain. In this study, to assess its clinical utility and evaluate whether it improves the diagnostic accuracy for HIT, we implemented HNA in conjunction with PF4/heparin ELISA over a 1-year period. A total of 1194 patient samples were submitted to the laboratory for testing from December 2015 to November 2016. Heparin neutralization assay alone is a poor predictor for HIT, but it has high negative predictive value (NPV): Cases with %inhibition <70% are always negative for serotonin release assay. It improves the diagnostic positive predictive value (PPV) of ELISA without compromising sensitivity: ELISA optical density (OD) ≥1.4 alone has a sensitivity of 88% (14/16) and a PPV of 61% (14/23); with HNA %inhibition ≥70%, the sensitivity remains 88% (14/16) and PPV is 82% (14/17). 4Ts score correlates with ELISA OD and predicts HIT; the predictive accuracy of 4Ts score is further improved by HNA. Interestingly, HNA %inhibition of <70% correlates with low 4Ts scores. Based on its high NPV, HNA has the potential to facilitate more timely and accurate HIT diagnosis.

Intra-aortic balloon pumping and thrombocytopenia in patients with acute coronary syndrome : Incidence, risk factors, and prognosis

BACKGROUND

Thrombocytopenia is a frequently encountered phenomenon during intra-aortic balloon pumping (IABP), which may limit its prolonged utilization. The aim of the study was to explore the risk factors and clinical implications of IABP-associated thrombocytopenia in patients with acute coronary syndrome (ACS).

METHODS

We retrospectively analyzed the data of 222 patients with ACS undergoing invasive treatment strategy supported by IABP. The incidence and risk factors of IABP-associated thrombocytopenia, and the association between thrombocytopenia and relevant clinical endpoints (in-hospital death, bleeding according to the TIMI scale, and thromboembolic events), were analyzed.

RESULTS

IABP-associated thrombocytopenia was observed in 54.5% (121/222) of the patients. The incidence of thrombocytopenia was higher and the magnitude of reduction in platelet count was greater in the Arrow balloon group (n = 89) compared with the Datascope balloon group (n = 133; 68.5% vs. 45.1%, p = 0.001; 48.7% vs. 33.2%, p < 0.001; respectively). Independent predictors of thrombocytopenia included older age and Arrow balloon utilization (odds ratio [OR]: 1.054; 95% confidence interval [CI]: 1.028-1.080; p<0.001; OR: 2.468; 95%CI: 1.375-4.431; p = 0.002; respectively). The incidence of in-hospital death was higher in patients who developed thrombocytopenia than those who did not (9.1% vs. 2.0%, p = 0.041), and thrombocytopenia was correlated with in-hospital death (OR: 5.932; 95%CI: 1.221-28.822; p = 0.027). However, the rates of TIMI bleeding and thromboembolic events were similar between the two groups (5.8% vs. 5.0%, p = 1.000; 3.2% vs. 6.0%, p = 0.518; respectively), and thrombocytopenia was not associated with TIMI bleeding or thromboembolic events (OR: 0.940; 95%CI: 0.267-3.307; p = 0.923; OR: 0.541, 95%CI: 0.148-1.974, p = 0.352; respectively).

CONCLUSION

IABP-associated thrombocytopenia occurred in 54.5% of patients with ACS undergoing an invasive strategy and it was correlated with increased in-hospital mortality. Older age and use of the Arrow balloon may predict IABP-associated thrombocytopenia.

The association between platelet transfusions and bleeding in critically ill patients with thrombocytopenia

BACKGROUND

Platelet transfusions are commonly used to treat critically ill patients with thrombocytopenia. Whether platelet transfusions are associated with a reduction in the risk of major bleeding is unknown.

PATIENTS/METHODS

Observational cohort study nested in a previous multicenter, randomized thromboprophylaxis trial in the intensive care unit (ICU). The objective was to evaluate the association between platelet transfusions and adjudicated major bleeding events. Platelet transfusion episodes were reviewed for timing of administration, product type, and dose. Major bleeding with and without platelet transfusions was adjusted for severity of thrombocytopenia, use of anti-platelet agents, surgery and other covariates. Secondary outcomes were thrombosis, death in ICU and platelet count increment.

RESULTS

Among 2,256 patients, 71 (3.1%) received 190 platelet transfusions. Of those, 121 (63.7%) were administered to 54 non-bleeding, thrombocytopenic patients. Adjusted rates of major bleeding were not statistically different with or without the administration of platelet transfusions (hazard ratio for transfused patients 0.85; 95% confidence interval, 0.42-1.72). We did not find a significant association between platelet transfusion use and thrombosis or death in ICU in adjusted analyses. Thrombocytopenia, anemia, major or minor bleeding and use of anticoagulants were associated with platelet transfusion administration. The median post-transfusion platelet count increment was 20×109/L at 3.5 hours post-transfusion.

CONCLUSIONS

Rates of major bleeding were not different for patients who did and did not receive platelet transfusions. Inferences were limited by the small number of transfused patients. Clinical trials are needed to better investigate the potential hemostatic benefit and potential harms of platelet transfusions for this high-risk population.

Nutrition Support for Critically Ill Patients With Cancer

Oncology patients often experience the classic signs of malnutrition-weight loss as well as fat and muscle wasting, which have been associated with poor tolerance to treatment and increased morbidity and mortality. Nutrition status may be an important factor in determining tolerance to treatment and outcomes associated with it. Thus, identification of those with preexisting malnutrition or who are at risk for developing malnutrition is crucial not only at time of cancer diagnosis but also throughout the treatment course so that nutrition interventions may be implemented to prevent development or worsening of malnutrition in this high-risk population. These patients often have extremely complicated hospital courses due to the aggressive nature of the disease and treatment, leading to intensive care unit admission and periods of critical illness. Critical illness is associated with catabolism, extreme stress on the body, and a state of systemic inflammation. During critical illness, it is important to provide adequate nutrition to prevent further break down of lean muscle mass and oxidative cellular injury and to regulate favorable immune responses. The purpose of this review is to discuss the importance of nutrition screening and assessment for the critically ill patient with cancer; to appropriately identify those at risk for, or who have developed, malnutrition; and to provide appropriate interventions to optimize nutrition status. This review also discusses the complications and difficulties associated with feeding this patient population and offers nutrition support recommendations.

Survival, bacterial clearance and thrombocytopenia are improved in polymicrobial sepsis by targeting nuclear transport shuttles

The rising tide of sepsis, a leading cause of death in the US and globally, is not adequately controlled by current antimicrobial therapies and supportive measures, thereby requiring new adjunctive treatments. Severe microvascular injury and multiple organ failure in sepsis are attributed to a "genomic storm" resulting from changes in microbial and host genomes encoding virulence factors and endogenous inflammatory mediators, respectively. This storm is mediated by stress-responsive transcription factors that are ferried to the nucleus by nuclear transport shuttles importins/karyopherins. We studied the impact of simultaneously targeting two of these shuttles, importin alpha 5 (Imp α5) and importin beta 1 (Imp β1), with a cell-penetrating Nuclear Transport Modifier (NTM) in a mouse model of polymicrobial sepsis. NTM reduced nuclear import of stress-responsive transcription factors nuclear factor kappa B, signal transducer and activator of transcription 1 alpha, and activator protein 1 in liver, which was also protected from sepsis-associated metabolic changes. Strikingly, NTM without antimicrobial therapy improved bacterial clearance in blood, spleen, and lungs, wherein a 700-fold reduction in bacterial burden was achieved while production of proinflammatory cytokines and chemokines in blood plasma was suppressed. Furthermore, NTM significantly improved thrombocytopenia, a prominent sign of microvascular injury in sepsis, inhibited neutrophil infiltration in the liver, decreased L-selectin, and normalized plasma levels of E-selectin and P-selectin, indicating reduced microvascular injury. Importantly, NTM combined with antimicrobial therapy extended the median time to death from 42 to 83 hours and increased survival from 30% to 55% (p = 0.022) as compared to antimicrobial therapy alone. This study documents the fundamental role of nuclear signaling mediated by Imp α5 and Imp β1 in the mechanism of polymicrobial sepsis and highlights the potential for targeting nuclear transport as an adjunctive therapy in sepsis management.

Recognition and Management of Hemostatic Disorders in Critically Ill Patients Needing to Undergo an Invasive Procedure

Abnormal laboratory coagulation test results are frequently documented in critically ill patients, and these patients often also need to undergo invasive procedures. Clinicians have an understandable desire to minimize any perceived heightened risk of bleeding complications in those patients who require invasive procedures. In this setting, prophylactic administration of platelets or plasma is commonplace. This review explores the nature of these sequential statements and the degree to which these statements are supported by evidence. We discuss the complexity of managing the low risk of procedure-related bleeding in a setting where coagulation tests fail to reliably predict this risk. The role of prophylactic transfusion of platelets and plasma and correction of medication-induced coagulopathy is also reviewed. New strategies are required to improve the evidence base, including novel methodological approaches or the use of a clinical scoring system.

Etiology and complications of thrombocytopenia in hospitalized medical patients

To determine incidence, risk factors, hematologic complications, and prognostic significance of thrombocytopenia in the general medicine population, we performed a single-institutional, retrospective study of all adult patients admitted to a general medical ward from January 1st, 2014 to December 31st, 2014 with hospital-acquired thrombocytopenia. Those with moderate thrombocytopenia, defined as a platelet count nadir of <100 × 10^9/L and/or a >50% relative decline, were compared to those with less severe thrombocytopenia. Of the 7420 patients admitted, 465 (6.3%) developed hospital-acquired thrombocytopenia. Infection and moderate thrombocytopenia were present in 56 and 23%, respectively. Severe sepsis and antibiotic use were both associated with moderate thrombocytopenia, and proton pump inhibitor use was statistically significant in both univariate and multivariate analysis. Hematologic complications were more frequent with moderate thrombocytopenia, including frequency of HIT testing and red blood cell transfusions. Outcome metrics including transfer to an intensive care unit (OR 6.78), death during admission (OR 6.85), and length of stay (10.6 vs. 5.1 days) were all associated with moderate thrombocytopenia. Thrombocytopenia is associated with poor prognosis, and the association between moderate thrombocytopenia and proton pump inhibitor use is relatively novel and should be validated in prospective studies.

Evaluation of platelet function in thrombocytopenia

Whole blood aggregometry is a functional assay for determination of platelet function. Until now, whole blood aggregometry has not been considered feasible at low platelet counts. Hence, the objectives of the present study were to explore platelet function in thrombocytopenia using a novel index of impedance aggregometry adjusted for platelet count and evaluate the association to platelet function assessed by flow cytometry. Hirudin anticoagulated blood was collected from 20 healthy volunteers, 20 patients with primary immune thrombocytopenia (ITP), and 17 hematological cancer patients. Platelet function was analyzed by impedance aggregometry and by flow cytometry. Collagen, adenosine diphosphate, thrombin receptor agonist peptide-6, and ristocetin were used as agonists for both analyses. Thrombocytopenia in healthy whole blood was induced in vitro employing a recently published method. Platelet aggregation of thrombocytopenic patients was evaluated relative to the aggregation of healthy volunteers at the same platelet count. In flow cytometry, platelet function was described as expression of the platelet surface glycoproteins: bound fibrinogen, CD63, and P-selectin. Similar platelet counts were obtained in the patient groups (p = 0.69) (range: 13-129 × 10⁹/l). Aggregation adjusted for platelet count was significantly increased in ITP patients compared to healthy platelets across all agonists. The platelet aggregation was high in the 95% prediction interval, with 18 ITP patients above the prediction interval in at least two agonists. In contrast, the platelet aggregation was low in the prediction interval in cancer patients, and three cancer patients with platelet aggregation below the prediction interval in at least one agonist. ITP patients displayed increased expression of bound fibrinogen and CD63 following activation, compared with particularly cancer patients, but also compared with healthy platelets. This study demonstrated the feasibility of a novel approach to perform platelet function analyses in thrombocytopenia using impedance aggregometry adjusted for platelet count.

Thrombocytopenia in hospitalized patients with severe clostridium difficile infection

Clostridium difficile infection (CDI) is a common cause of nosocomial diarrhea and colitis. The incidence and prognostic significance of thrombocytopenia as related to mode of acquisition (hospital vs. community), NAP1/027 strain, and disease severity has not been examined. We performed a single-institution retrospective analysis of all adult inpatients from 2013 to 2014 diagnosed with CDI during their hospitalization to document the incidence/prevalence of thrombocytopenia and associated outcomes. Severe disease was defined by a composite endpoint of inpatient death, death within 30 days of discharge, presence of septic shock, or need for colectomy during hospitalization. Of the 533 patients diagnosed with CDI, moderate thrombocytopenia (platelet count <100 × 10⁹/L at time of CDI diagnosis) was present in 15 % of the total cohort and incident thrombocytopenia developed in 3 % of patients after admission. Thrombocytopenia was more common in hospital-acquired disease and associated with increased length of stay, but was not associated with treatment failure. Those with moderate thrombocytopenia were more likely to have severe disease, after controlling for white blood cell count, albumin, and creatinine. Moderate thrombocytopenia is associated with poor prognosis and is a potential risk stratification tool for severe CDI.

Thrombocytopenia on the first day of emergency department visit predicts higher risk of acute kidney injury among elderly patients

Background

Few studies have addressed risk factors for acute kidney injury (AKI) in geriatric patients. We investigated whether thrombocytopenia was a risk factor for AKI in geriatric patients with medical illnesses.

Methods

A prospective cohort study was conducted, by recruiting elderly (≥65 years) patients who visited the emergency department (ED) for medical illnesses during 2014. They all received hemogram for platelet count determination, and were stratified according to the presence of thrombocytopenia (platelets, <150 K/μL) during their initial ED evaluation. They were prospectively followed up during their ED stay. We analyzed the relationship between the diagnosis of thrombocytopenia and subsequent AKI after ED stay, using Cox proportional hazard modeling, with platelet count as a continuous variable or thrombocytopenia as a categorical variable.

Results

Of 136 elderly patients (mean age of 80.7 ± 8.2 years, 40% with chronic kidney disease, and 39% with diabetes) enrolled, 22.8% presented with thrombocytopenia, without differences in baseline renal function. After a mean ED stay of 4.4 ± 2.1 days, 41.9% developed AKI (52.6% Kidney Disease Improving Global Outcomes [KDIGO] grade 1, 24.6% grade 2, and 22.8% grade 3). Patients with higher AKI severity had stepwise lower platelet counts compared to those without AKI. The Cox proportional hazard model revealed that lower platelet count as a continuous variable (hazard ratio [HR] 0.984, 95% confidence interval [CI] 0.975–0.994) and as a categorical variable (presence of thrombocytopenia) (HR 1.86, 95% CI 1.06–3.27) increased the risk of AKI. The sensitivity analyses accounting for nephrotoxic medications use, including non-steroidal anti-inflammatory drugs, vancomycin, and contrast, yielded similar results.

Discussion

Thrombocytopenia is common among ED-visiting elderly, and the potential relationship between platelet counts and the risk of AKI suggests the utility of checking hemogram for those at-risk ofdeveloping adverse renal events.

Conclusion

Thrombocytopenia on initial presentation might indicate an increased risk of AKI among elderly patients with medical illnesses.

Phage-Derived Protein Induces Increased Platelet Activation and Is Associated with Mortality in Patients with Invasive Pneumococcal Disease

To improve our understanding about the severity of invasive pneumococcal disease (IPD), we investigated the association between the genotype of Streptococcus pneumoniae and disease outcomes for 349 bacteremic patients. A pneumococcal genome-wide association study (GWAS) demonstrated a strong correlation between 30-day mortality and the presence of the phage-derived gene pblB, encoding a platelet-binding protein whose effects on platelet activation were previously unknown. Platelets are increasingly recognized as key players of the innate immune system, and in sepsis, excessive platelet activation contributes to microvascular obstruction, tissue hypoperfusion, and finally multiorgan failure, leading to mortality. Our in vitro studies revealed that pblB expression was induced by fluoroquinolones but not by the beta-lactam antibiotic penicillin G. Subsequently, we determined pblB induction and platelet activation by incubating whole blood with the wild type or a pblB knockout mutant in the presence or absence of antibiotics commonly administered to our patient cohort. pblB-dependent enhancement of platelet activation, as measured by increased expression of the α-granule protein P-selectin, the binding of fibrinogen to the activated αIIbβ3 receptor, and the formation of platelet-monocyte complex occurred irrespective of antibiotic exposure. In conclusion, the presence of pblB on the pneumococcal chromosome potentially leads to increased mortality in patients with an invasive S. pneumoniae infection, which may be explained by enhanced platelet activation. This study highlights the clinical utility of a bacterial GWAS, followed by functional characterization, to identify bacterial factors involved in disease severity.

The exact mechanisms causing mortality in invasive pneumococcal disease (IPD) patients are not completely understood. We examined 349 patients with IPD and found in a bacterial genome-wide association study (GWAS) that the presence of the phage-derived gene pblB was associated with mortality in the first 30 days after hospitalization. Although pblB has been extensively studied in Streptococcus mitis, its consequence for the interaction between platelets and Streptococcus pneumoniae is largely unknown. Platelets are important in immunity and inflammation, and excessive platelet activation contributes to microvascular obstruction and multiorgan failure, leading to mortality. We therefore developed this study to assess whether the expression of pblB might increase the risk of death for IPD patients through its effect on enhanced platelet activation. This study also shows the value of integrating extensive bacterial genomics and clinical data in predicting and understanding pathogen virulence, which in turn will help to improve prognosis and therapy.

[Thrombocytopenia in the intensive care unit]

Thrombozytopenie ist ein häufiges Phänomen in der Intensivmedizin. Eine Vielzahl von Ursachen kann für erniedrigte Plättchenzahlen verantwortlich sein. Da Plättchen Teil der primären Hämostase sind, ist Blutungsneigung die wichtigste Komplikation einer Thrombopenie. Strukturiertes Aufarbeiten der Differenzialdiagnose und Identifikation der Ursache ist essenziell, da die verschiedenen Krankheitsbilder unterschiedliche diagnostische und therapeutische Maßnahmen erfordern. Eine erniedrigte Thrombozytenzahl ist ein starker Prädiktor der Mortalität kritisch kranker Patienten.

Dieser Artikel fasst die Differenzialdiagnose und die diagnostische Aufarbeitung der Thrombopenie in der Intensivmedizin zusammen und gibt einen Überblick über die wichtigsten Krankheitsbilder und die therapeutischen Optionen.

How do we approach thrombocytopenia in critically ill patients?

A low platelet count is a frequently encountered haematological abnormality in patients treated in intensive treatment units (ITUs). Although severe thrombocytopenia (platelet count <20 × 10⁹ /l) can be associated with bleeding, even moderate-degree thrombocytopenia is associated with organ failure and adverse prognosis. The aetiology for thrombocytopenia in ITU is often multifactorial and correcting one aetiology may not normalise the low platelet count. The classical view for thrombocytopenia in this setting is consumption associated with thrombin-mediated platelet activation, but other concepts, including platelet adhesion to endothelial cells and leucocytes, platelet aggregation by increased von Willebrand factor release, red cell damage and histone release, and platelet destruction by the complement system, have recently been described. The management of severe thrombocytopenia is platelet transfusion in the presence of active bleeding or invasive procedure, but the risk-benefit of prophylactic platelet transfusions in this setting is uncertain. In this review, the incidence and mechanisms of thrombocytopenia in patients with ITU, its prognostic significance and the impact on organ function is discussed. A practical approach based on the authors' experience is described to guide management of a critically ill patient who develops thrombocytopenia.

How I evaluate and treat thrombocytopenia in the intensive care unit patient

Multiple causes (pseudothrombocytopenia, hemodilution, increased consumption, decreased production, increased sequestration, and immune-mediated destruction of platelets) alone or in combination make thrombocytopenia very common in intensive care unit (ICU) patients. Persisting thrombocytopenia in critically ill patients is associated with, but not causative of, increased mortality. Identification of the underlying cause is key for management decisions in individual patients. While platelet transfusion might be indicated in patients with impaired platelet production or increased platelet destruction, it could be deleterious in patients with increased intravascular platelet activation. Sepsis and trauma are the most common causes of thrombocytopenia in the ICU. In these patients, treatment of the underlying disease will also increase platelet counts. Heparin-induced thrombocytopenia requires alternative anticoagulation at a therapeutic dose and immune thrombocytopenia immunomodulatory treatment. Thrombocytopenia with symptomatic bleeding at or above World Health Organization grade 2 or planned invasive procedures are established indications for platelet transfusions, while the evidence for a benefit of prophylactic platelet transfusions is weak and controversial. If the platelet count does not increase after transfusion of 2 fresh ABO blood group-identical platelet concentrates (therapeutic units), ongoing platelet consumption and high-titer anti-HLA class I antibodies should be considered. The latter requires transfusion of HLA-compatible platelet concentrates.

Platelets in Pulmonary Immune Responses and Inflammatory Lung Diseases

Platelets are essential for physiological hemostasis and are central in pathological thrombosis. These are their traditional and best known activities in health and disease. In addition, however, platelets have specializations that broaden their functional repertoire considerably. These functional capabilities, some of which are recently discovered, include the ability to sense and respond to infectious and immune signals and to act as inflammatory effector cells. Human platelets and platelets from mice and other experimental animals can link the innate and adaptive limbs of the immune system and act across the immune continuum, often also linking immune and hemostatic functions. Traditional and newly recognized facets of the biology of platelets are relevant to defensive, physiological immune responses of the lungs and to inflammatory lung diseases. The emerging view of platelets as blood cells that are much more diverse and versatile than previously thought further predicts that additional features of the biology of platelets and of megakaryocytes, the precursors of platelets, will be discovered and that some of these will also influence pulmonary immune defenses and inflammatory injury.

Platelet Transfusions in Pediatric Intensive Care

OBJECTIVES

To characterize the determinants of platelet transfusion in a PICU and determine whether there exists an association between platelet transfusion and adverse outcomes.

DESIGN

Prospective observational single center study, combined with a self-administered survey.

SETTING

PICU of Sainte-Justine Hospital, a university-affiliated tertiary care institution.

PATIENTS

All children admitted to the PICU from April 2009 to April 2010.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

Among 842 consecutive PICU admissions, 60 patients (7.1%) received at least one platelet transfusion while in PICU. In the univariate analysis, significant determinants for platelet transfusion were admission Pediatric Risk of Mortality Score greater than 10 (odds ratio, 6.80; 95% CI, 2.5-18.3; p < 0.01) and Pediatric Logistic Organ Dysfunction scores greater than 20 (odds ratio, 26.9; 95% CI, 8.88-81.5; p < 0.01), history of malignancy (odds ratio, 5.08; 95% CI, 2.43-10.68; p < 0.01), thrombocytopenia (platelet count, < 50 × 10/L or < 50,000/mm) (odds ratio, 141; 95% CI, 50.4-394.5; p < 0.01), use of heparin (odds ratio, 3.03; 95% CI, 1.40-6.37; p < 0.01), shock (odds ratio, 5.73; 95% CI, 2.85-11.5; p < 0.01), and multiple organ dysfunction syndrome (odds ratio, 10.41; 95% CI, 5.89-10.40; p < 0.01). In the multivariate analysis, platelet count less than 50 × 10/L (odds ratio, 138; 95% CI, 42.6-449; p < 0.01) and age less than 12 months (odds ratio, 3.06; 95% CI, 1.03-9.10; p = 0.02) remained statistically significant determinants. The attending physicians were asked why they gave a platelet transfusion; the most frequent justification was prophylactic platelet transfusion in presence of thrombocytopenia with an average pretransfusion platelet count of 32 ± 27 × 10/L (median, 21), followed by active bleeding with an average pretransfusion platelet count of 76 ± 39 × 10/L (median, 72). Platelet transfusions were associated with the subsequent development of multiple organ dysfunction syndrome (odds ratio, 2.53; 95% CI, 1.18-5.43; p = 0.03) and mortality (odds ratio, 10.1; 95% CI, 4.48-22.7; p < 0.01).

CONCLUSIONS

Among children, 7.1% received at least one platelet transfusion while in PICU. Thrombocytopenia and active bleeding were significant determinants of platelet transfusion. Platelet transfusions were associated with the development of multiple organ dysfunction syndrome and increased mortality.

Effect of Persistent Thrombocytopenia on Mortality in Surgical Critical Care Patients

Thrombocytopenia is common among surgical critically ill patients. The relationship between the duration of thrombocytopenia and mortality is not well studied. This retrospective 12-month cohort study was designed to evaluate the association between persistent thrombocytopenia and mortality among surgical critically ill patients to determine the risk factors for persistent thrombocytopenia. The study included adult patients consecutively admitted to the surgical intensive care unit (SICU) at our institution. Patients with a diagnosis of thrombocytopenia were identified from a prospective critical care database. We defined patients with persistent thrombocytopenia as those with thrombocytopenia lasting more than 7 consecutive days. The primary outcome of this study was 28-day mortality and the secondary outcomes were lengths of SICU stay and hospital stay. Fifty-one patients experienced persistent thrombocytopenia and 71 experienced nonpersistent thrombocytopenia. Among patients with persistent thrombocytopenia, mortality was significantly higher, and SICU and hospital stays were longer than those with nonpersistent thrombocytopenia. Risk factor analysis failed to predict which patients with thrombocytopenia would develop into persistent thrombocytopenia. Persistent thrombocytopenia is a clinically significant disorder and is associated with poorer outcomes. Future studies are needed to further define this process.

Myelodysplastic Syndromes in the Elderly: Treatment Options and Personalized Management

Myelodysplastic syndromes (MDS) are typical diseases of the elderly, with a median age of 68-75 years at initial diagnosis. Demographic changes producing an increased proportion of elderly in our societies mean the incidence of MDS will rise dramatically. Considering the increasing number of treatment options, ranging from best supportive care to hematopoietic stem cell transplantation (HSCT), decision making is rather complex in this cohort of patients. Moreover, aspects of the aging process also have to be considered in therapy planning. Treatment of elderly MDS patients is dependent on the patient's individual risk and prognosis. Comorbidities play an essential role as predictors of survival and therapy tolerance. Age-adjusted models and the use of geriatric assessment scores are described as a basis for individualized treatment algorithms. Specific treatment recommendations for the different groups of patients are given. Currently available therapeutic agents, including supportive care, erythropoiesis-stimulating agents (ESAs), immune-modulating agents, hypomethylating agents, and HSCT are described in detail and discussed with a special focus on elderly MDS patients. The inclusion of elderly patients in clinical trials is of utmost importance to obtain data on efficacy and safety in this particular group of patients. Endpoints relevant for the elderly should be integrated, including maintenance of quality of life and functional activities as well as evaluation of use of healthcare resources.

[Thrombocytopenia in the intensive care unit : Diagnosis, differential diagnosis, and treatment]

Thrombozytopenie ist ein häufiges Phänomen in der Intensivmedizin. Eine Vielzahl von Ursachen kann für erniedrigte Plättchenzahlen verantwortlich sein. Da Plättchen Teil der primären Hämostase sind, ist Blutungsneigung die wichtigste Komplikation einer Thrombopenie. Strukturiertes Aufarbeiten der Differenzialdiagnose und Identifikation der Ursache ist essenziell, da die verschiedenen Krankheitsbilder unterschiedliche diagnostische und therapeutische Maßnahmen erfordern. Eine erniedrigte Thrombozytenzahl ist ein starker Prädiktor der Mortalität kritisch kranker Patienten.

Dieser Artikel fasst die Differenzialdiagnose und die diagnostische Aufarbeitung der Thrombopenie in der Intensivmedizin zusammen und gibt einen Überblick über die wichtigsten Krankheitsbilder und die therapeutischen Optionen.

Platelet Counts, Acute Kidney Injury, and Mortality after Coronary Artery Bypass Grafting Surgery

BACKGROUND

Cardiac surgery requiring cardiopulmonary bypass is associated with platelet activation. Because platelets are increasingly recognized as important effectors of ischemia and end-organ inflammatory injury, the authors explored whether postoperative nadir platelet counts are associated with acute kidney injury (AKI) and mortality after coronary artery bypass grafting (CABG) surgery.

METHODS

The authors evaluated 4,217 adult patients who underwent CABG surgery. Postoperative nadir platelet counts were defined as the lowest in-hospital values and were used as a continuous predictor of postoperative AKI and mortality. Nadir values in the lowest 10th percentile were also used as a categorical predictor. Multivariable logistic regression and Cox proportional hazard models examined the association between postoperative platelet counts, postoperative AKI, and mortality.

RESULTS

The median postoperative nadir platelet count was 121 × 10/l. The incidence of postoperative AKI was 54%, including 9.5% (215 patients) and 3.4% (76 patients) who experienced stages II and III AKI, respectively. For every 30 × 10/l decrease in platelet counts, the risk for postoperative AKI increased by 14% (adjusted odds ratio, 1.14; 95% CI, 1.09 to 1.20; P < 0.0001). Patients with platelet counts in the lowest 10th percentile were three times more likely to progress to a higher severity of postoperative AKI (adjusted proportional odds ratio, 3.04; 95% CI, 2.26 to 4.07; P < 0.0001) and had associated increased risk for mortality immediately after surgery (adjusted hazard ratio, 5.46; 95% CI, 3.79 to 7.89; P < 0.0001).

CONCLUSION

The authors found a significant association between postoperative nadir platelet counts and AKI and short-term mortality after CABG surgery.

Use of platelet transfusions prior to lumbar punctures or epidural anaesthesia for the prevention of complications in people with thrombocytopenia

BACKGROUND

People with a low platelet count (thrombocytopenia) often require lumbar punctures or an epidural anaesthetic. Lumbar punctures can be diagnostic (haematological malignancies, epidural haematoma, meningitis) or therapeutic (spinal anaesthetic, administration of chemotherapy). Epidural catheters are placed for administration of epidural anaesthetic. Current practice in many countries is to correct thrombocytopenia with platelet transfusions prior to lumbar punctures and epidural anaesthesia, in order to mitigate the risk of serious procedure-related bleeding. However, the platelet count threshold recommended prior to these procedures varies significantly from country to country. This indicates significant uncertainty among clinicians of the correct management of these patients. The risk of bleeding appears to be low but if bleeding occurs it can be very serious (spinal haematoma). Therefore, people may be exposed to the risks of a platelet transfusion without any obvious clinical benefit.

OBJECTIVES

To assess the effects of different platelet transfusion thresholds prior to a lumbar puncture or epidural anaesthesia in people with thrombocytopenia (low platelet count).

SEARCH METHODS

We searched for randomised controlled trials (RCTs) in CENTRAL (The Cochrane Library 2016, Issue 3), MEDLINE (from 1946), EMBASE (from 1974), the Transfusion Evidence Library (from 1950) and ongoing trial databases to 3 March 2016.

SELECTION CRITERIA

We included RCTs involving transfusions of platelet concentrates, prepared either from individual units of whole blood or by apheresis, and given to prevent bleeding in people of any age with thrombocytopenia requiring insertion of a lumbar puncture needle or epidural catheter. We only included RCTs published in English.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane.

MAIN RESULTS

We identified no completed or ongoing RCTs in English. We did not exclude any completed or ongoing RCTs because they were published in another language.

AUTHORS' CONCLUSIONS

There is no evidence from RCTs to determine what is the correct platelet transfusion threshold prior to insertion of a lumbar puncture needle or epidural catheter. There are no ongoing registered RCTs assessing the effects of different platelet transfusion thresholds prior to the insertion of a lumbar puncture or epidural anaesthesia in people with thrombocytopenia. Any future RCT would need to be very large to detect a difference in the risk of bleeding. We would need to design a study with at least 47,030 participants to be able to detect an increase in the number of people who had major procedure-related bleeding from 1 in 1000 to 2 in 1000.