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.

Thrombocytopenia and extracorporeal membrane oxygenation in adults with acute respiratory failure: a cohort study

PURPOSE

The association between extracorporeal membrane oxygenation (ECMO) use and the development of thrombocytopenia is widely presumed yet weakly demonstrated. We hypothesized that longer duration of ECMO support would be independently associated with worsened thrombocytopenia.

METHODS

We performed a single-center retrospective cohort study of 100 adults who received ECMO for acute respiratory failure. We used generalized estimating equations to test the association between days on ECMO and daily percentage of platelets compared to the first post-cannulation platelet count. We constructed a multivariable logistic regression model with backwards stepwise elimination to identify clinical predictors of severe thrombocytopenia (≤50,000/μL) while on ECMO.

RESULTS

Days on ECMO was not associated with a decrease in platelet count in the unadjusted analysis (β -0.85, 95 % CI -2.05 to 0.36), nor after considering and controlling for days hospitalized prior to ECMO, APACHE II score, platelet transfusions, and potential thrombocytopenia-inducing medications (β -0.83, 95 % CI -1.9 to 0.25). Twenty-two subjects (22 %) developed severe thrombocytopenia. The APACHE II score and platelet count at the time of cannulation predicted the development of severe thrombocytopenia. The odds of developing severe thrombocytopenia increased 35 % for every 5-point increase in APACHE II score (OR 1.35, 95 % CI 0.94-1.94) and increased 35 % for every 25,000/μL platelets below a mean at cannulation of 188,000/μL (OR 1.35, 95 % CI 1.10-1.64).

CONCLUSIONS

Duration of ECMO is not associated with the development of thrombocytopenia. The severity of critical illness and platelet count at the time of cannulation predict the development of severe thrombocytopenia while receiving ECMO for respiratory failure. Future studies should validate these findings, especially in cohorts with more venoarterial ECMO patients, and should characterize the association between thrombocytopenia and bleeding events while on ECMO.

Thrombocytopenia: A Risk Factor of Mortality for Patients with Sepsis in the Intensive Care Unit

OBJECTIVES

The objective of this study was to evaluate the intensive care unit (ICU) and long-term mortality in sepsis patients with/without thrombocytopenia on the fifth day of ICU admission.

MATERIALS AND METHODS

The retrospective observational cohort study was performed in a teaching hospital, and patients with sepsis who stayed more than 4 days in the ICU between January 2012 and December 2012 were included. Patients were divided into two groups according to thier platelet count at fifth day of ICU stay: Group 1, < 150.000/μL; Group 2, >150.000/μL. Patients having thrombocytopenia on admission were excluded. The patients' characteristics, comorbid diseases, body mass index, arterial blood gas analysis and blood biochemistry results, SIRS criteria, Acute Physiological and Chronic Health Evaluation Score II (APACHE II), implication of invasive and non-invasive mechanical ventilation, use of sedation, nutrition information, and culture results of microbiological samples were recorded. The groups were compared according to the recorded data. Logistic regression analysis was performed for ICU mortality; the Kaplan-Meier test was used to evaluate 12-month survival after ICU discharge.

RESULTS

During the period, 1003 patients were admitted to the ICU; 307 sepsis patients were included in the study. Group 1 (n= 67) and Group 2 (n=240) had similar patient characteristics and sepsis findings. The groups had similar ICU and hospital stays; mortality was higher in Group 1 than in Group 2 (40.3% vs. 17.5%, respectively, p< 0.001). Fifth day thrombocytopenia, septic shock, male gender, and low albumin levels were found to be risk factors of ICU mortality; the respective odds ratios, 95% confidence intervals, and p values for these factors were 3.03, [1.15-7.45], p= 0.025; 4.97, [1.79-13.86], p= 0.002; 3.61, [1.27-10.23], p= 0.001; and 0.19, [0.07-0.52], p= 0.001. Follow-up after a year indicated that 124 out of 238 (52.1%) patients died, and 50% of the deaths occurred in the first 2 months. Kaplan-Meier analysis revealed no statistically significant effects of thrombocytopenia at ICU day 5 on 12-month mortality after ICU discharge.

CONCLUSION

Higher rates of septic shock and mortality were seen in sepsis patients with thrombocytopenia in the ICU. The measurement of thrombocytopenia in the ICU, which is easy and low-cost, may help to predict mortality. Thus, precautions can be taken early in patient treatment and follow-up. As we know, early intervention is crucial in the approach to sepsis.

Platelet transfusions in cancer patients with hypoproliferative thrombocytopenia in the intensive care unit

Background

Thrombocytopenia is a frequent finding in critically ill cancer patients for whom indications of platelet transfusions are unclear. We herein addressed the current practices in platelet transfusion and the risk of bleeding in cancer patients with hypoproliferative thrombocytopenia in the intensive care unit (ICU).

Methods

A retrospective monocenter study over a 7-year period was conducted in a medical ICU. Adult patients with malignancies and hypoproliferative thrombocytopenia, and who received at least one platelet concentrate during their ICU stay, were included.

Results

296 patients were included and received a total of 904 platelet transfusions, for prophylactic indications in 300 (33.2 %) episodes, for securing an invasive procedure in 257 (28.4 %), and for treatment of minor to major bleeding manifestations in 347 (38.4 %). Most prophylactic transfusions (80 %) were performed at platelet count thresholds below 10–20 × 10⁹/L. Platelet increments were generally low in all three indications, 10 (interquartile range 2–25), 11 (2–25), and 8 (0–21) × 10⁹/L, respectively. A total of 97 major ICU-acquired bleeding events occurred in 40 patients. About half of those bleeding episodes (54.7 %) occurred at platelet counts below 20 × 10⁹/L. However, neither low admission platelet count nor low nadir platelet counts were predictive of ICU-acquired bleeding. The in-ICU mortality rate tended to be higher in patients with severe ICU-acquired bleeding events (50 vs. 36 %).

Conclusions

Most prophylactic platelet transfusions were given using thresholds of 10–20 × 10⁹/L in critically ill thrombocytopenic cancer patients. The individual risk of ICU-acquired severe bleeding appears hardly predictable with the depth of thrombocytopenia.

Group G streptococci mediate fibrinogen-dependent platelet aggregation leading to transient entrapment in platelet aggregates

Platelets have been reported to become activated in response to bacteria and this is proposed to contribute to the acute response to bacterial infection. In the present study, we investigated platelet aggregation in response to group G streptococci (GGS) in vitro in healthy human donors and in vivo in a mouse model of streptococcal sepsis. Platelet aggregation by GGS was dependent on the bacterial surface protein FOG and engagement of the platelet fibrinogen receptor; however, it was independent of IgG and the platelet Fc receptor. Platelets exerted no antibacterial effects on the bacteria, and aggregates formed were markedly unstable, allowing bacteria to rapidly return to the plasma and grow post-aggregation. Thrombocytopenia and platelet activation occurred during invasive infection with GGS, and platelets were demonstrated to contribute to bacterial dissemination during infection. These findings reveal an important role for bacteria-platelet interactions during the pathogenesis of streptococcal infection.

Pitfalls in the diagnosis of heparin-Induced thrombocytopenia: A 6-year experience from a reference laboratory

Heparin-induced thrombocytopenia (HIT) is caused by platelet-activating antibodies against complexes of platelet factor 4 (PF4) and heparin. The diagnosis of HIT is contingent on accurate and timely laboratory testing. Recently, alternative anticoagulants for the treatment of HIT have been introduced along with algorithms for better HIT diagnosis. However, the increased reliance on immunoassays for the diagnosis of HIT may have harmful consequences due to the high rate of false positive results. To compare trends and implications of current HIT testing approaches, we analyzed results over a six-year period from the McMaster University Platelet Immunology Reference Laboratory. From 2008 to 2013, 8,546 samples were investigated for HIT using both an in-house IgG-specific anti-PF4/heparin enzyme immunoassay (EIA) and the serotonin-release assay (SRA). Of 8,546 samples tested, 13.4% were true-positives (positive in both assays); 65.6% were true-negatives (negative in both assays); 20.9% were presumed false positive for HIT (EIA-positive/SRA-negative); and 0.2% were EIA-negative/SRA-positive. The frequency of EIA-positive/SRA-negative results increased over time (from 12.9% in 2008 to 22.9% in 2013). We found that the number of SRA-negative samples was reduced from referring centers that used an immunoassay as an initial screen; however, 41% of those samples tested negative in the immunoassay and in the SRA at the reference laboratory. The suspicion of HIT continues at a high rate and the agreement between the EIA and SRA test results remains problematic.

Platelet interaction with bacterial toxins and secreted products

Bacteria that enter the bloodstream will encounter components of the cellular and soluble immune response. Platelets contribute to this response and have emerged as an important target for bacterial pathogens. Bacteria produce diverse extracellular proteins and toxins that have been reported to modulate platelet function. These interactions can result in complete or incomplete platelet activation or inhibition of platelet activation, depending on the bacteria and bacterial product. The nature of the platelet response may be highly relevant to disease pathogenesis.

Association of the immature platelet fraction with sepsis diagnosis and severity

Management of Sepsis would greatly benefit from the incorporation of simple and informative new biomarkers in clinical practice. Ideally, a sepsis biomarker should segregate infected from non-infected patients, provide information about prognosis and organ-specific damage, and be accessible to most healthcare services. The immature platelet fraction (IPF) and immature reticulocyte fraction (IRF) are new analytical parameters of the complete blood count, that have been studied as biomarkers of several inflammatory conditions. Recently, a study performed in critically-ill patients suggested that IPF could be a more accurate sepsis biomarker than C-reactive protein (CRP) and procalcitonin. In this retrospective study we evaluated the performance of IPF and IRF as biomarkers of sepsis diagnosis and severity. 41 patients admitted to two intensive care units were evaluated, 12 of which with severe sepsis or septic shock, and 11 with non-complicated sepsis. Significantly higher IPF levels were observed in patients with severe sepsis/septic shock. IPF correlated with sepsis severity scores and presented the highest diagnostic accuracy for the presence of sepsis of all studied clinical and laboratory parameters. No significant differences were observed in IRF levels. Our results suggest that IPF levels could be used as a biomarker of sepsis diagnosis and severity.

Presence of Antiheparin/Platelet Factor 4 Immunoglobulin G Is Associated With Poor Prognosis in Patients With Suspected Disseminated Intravascular Coagulation

The underlying inflammatory or infectious condition in disseminated intravascular coagulation (DIC) may stimulate the formation of antiheparin/platelet factor 4 (PF4) antibody, and the resulting antibody may affect the clinical course of DIC. We investigated the prognosis of antiheparin/PF4 antibodies in patients with suspected DIC. We measured heparin/PF4 immunoglobulin G (IgG) and total antibody levels using an automated chemiluminescence system in 118 patients with DIC. Of the 118 patients, 13 (11.0%) patients were positive for total antiheparin/PF4, and 6 (5.1%) patients were positive for antiheparin/PF4 IgG. These 13 patients were negative for platelet-activating antibody and had low-heparin-induced thrombocytopenia probability scores. Patients with antiheparin/PF4 IgG were older and had lower antithrombin levels than patients without antiheparin/PF4 IgG. Patients with antiheparin/PF4 IgG had a higher risk of mortality than those without antiheparin/PF4 IgG. The presence of antiheparin/PF4 IgG in old age or low antithrombin level patients with DIC with old age or low antithrombin level suggests a poor prognosis.

[Coagulation disorders in the intensive care station]

Coagulation disorders are frequently encountered in the intensive care unit (ICU) and are challenging due to a variety of potential etiologies. Critically ill patients with coagulation abnormalities may present with an increased risk of bleeding, show coagulation activation resulting in thromboembolism, or have no specific symptoms. Hemostatic abnormalities observed in ICU patients range from isolated thrombocytopenia or prolonged global clotting tests to complex and life-threatening coagulation defects. Successful management of coagulation disorders requires prompt and accurate identification of the underlying cause. This review describes the most frequently occurring diagnoses found in intensive care patients with thrombocytopenia and coagulation test abnormalities and summarizes appropriate diagnostic interventions and current approaches to differential diagnosis.

Hospital-acquired thrombocytopenia

The development of thrombocytopenia is common in hospitalized patients and is associated with increased mortality. Frequent and important causes of thrombocytopenia in hospitalized patients include etiologies related to the underlying illness for which the patient is admitted, such as infection and disseminated intravascular coagulation, and iatrogenic etiologies such as drug-induced immune thrombocytopenia, heparin-induced thrombocytopenia, posttransfusion purpura, hemodilution, major surgery, and extracorporeal circuitry. This review presents a brief discussion of the pathophysiology, distinguishing clinical features, and management of these etiologies, and provides a diagnostic approach to hospital-acquired thrombocytopenia that considers the timing and severity of the platelet count fall, the presence of hemorrhage or thrombosis, the clinical context, and the peripheral blood smear. This approach may offer guidance to clinicians in distinguishing among the various causes of hospital-acquired thrombocytopenia and providing management appropriate to the etiology.

Immune functions of platelets

This review collects evidence about immune and inflammatory functions of platelets from a clinician's point of view. A focus on clinically relevant immune functions aims at stimulating further research, because the complexity of platelet immunity is incompletely understood and not yet translated into patient care. Platelets promote chronic inflammatory reactions (e.g. in atherosclerosis), modulate acute inflammatory disorders such as sepsis and other infections (participating in the host defense against pathogens), and contribute to exacerbations of autoimmune conditions (like asthma or arthritis). It would hence be obsolete to restrict a description of platelet functions to thrombosis and haemostasis--platelets clearly are the most abundant cells with immune functions in the circulation.

Clinical characteristics and prognostic significance of changes in platelet count in an internal medicine ward

BACKGROUND

The clinical characteristics and prognostic significance of changes in platelet count (PC) during hospitalization in internal medicine wards have not been well investigated.

METHODS

Demographic, clinical and laboratory data were collected from 345 patients admitted to an internal medicine ward. Following discharge, all-cause mortality was recorded. These data were compared, according to deltaPC (PC on discharge minus PC on admission): group 1 (drop in PC, deltaPC -50×10(9)/l), group 2 (no significant PC changes, deltaPC up to 50×10(9)/l) and group 3 (rise in PC, deltaPC +50×10(9)/l).

RESULTS

Groups 1, 2 and 3 comprised 64 (18.5%), 200 (58%) and 81 (23.5%) patients, respectively. Patients from group 3 were younger, more likely admitted for infection and less likely for cardiovascular disorder, and less often presenting with coronary artery disease, complex nursing care and thrombocytosis on admission or thrombocytopenia on discharge than patients from groups 1 and 2. Mean platelet volume was higher in group 2 on admission and lower in group 3 on discharge. During a median follow-up of 25 months, 146 (42.3%) of 345 patients died. The survival rate was higher for group 3 (65.4%) than for groups 1 (45.3%) and 2 (58.5%), p=0.003. In the entire cohort, each 100×10(9)/l increment of deltaPC was a powerful predictor of lower mortality (p=0.03, relative risk=0.83, 95% confidence interval=0.71-0.98).

CONCLUSIONS

Increased PC throughout hospitalization was associated with better prognosis than a drop or blunted rise in PC. The assessment of PC changes in an internal medicine ward may provide useful prognostic information.

Pneumonia, thrombosis and vascular disease

SUMMARY

An enhanced risk of cardiovascular mortality has been observed after pneumonia. Epidemiological studies have shown that respiratory tract infections are associated with an increased risk of thrombotic-related vascular disease such as myocardial infarction, ischemic stroke and venous thrombosis. Myocardial infarction and stroke have been detected essentially in the early phase of the disease (i.e. within 48 h from hospital admission), with an incidence ranging from as low as 1% to as high as 11%. Age, previous cardiovascular events and high pneumonia severity index were independent predictors of myocardial infarction; clinical predictors of stroke were not identified. Deep venous thrombosis and pulmonary embolism may also occur after pneumonia but incidence and clinical predictors must be defined. The biological plausibility of such an association may be deduced by experimental and clinical studies, showing that lung infection is complicated by platelet aggregation and clotting system activation, as documented by up-regulation of tissue factor and down-regulation of activated protein C. The effect of antithrombotic drugs has been examined in experimental and clinical studies but results are still inconclusive.

Percutaneous Cryoablation for Liver Cancer

Based on the primary tumor site, liver cancer can be divided into two categories: (1) primary liver cancer and (2) metastatic cancer to the liver from a distant primary site. Guided cryoablation via many imaging methods induces iceball formation and tumor necrosisand is an attractive option for treating unresectable hepatocellular carcinoma (HCC) and metastatic liver cancer. There are several advantages to using cryoablation for the treatment of liver cancer: it can be performed percutaneously, intraoperatively, and laparoscopically; iceball formation can be monitored; it has little impact on nearby large blood vessels; and it induces a cryo-immunological response in situ. Clinically, primary research has shown that percutaneous cryoablation of liver cancer is relatively safe and efficient, and it can be combined with other methods, such as radiation therapy, chemotherapy, and immunology, to control disease. Although research is preliminary, cryosurgery is fast becoming an alternative treatment method for HCC or liver tumors. Here, we review the mechanisms of liver tumor cryoablation, cryoablation program selection, clinical efficiency, and complications following treatment.

Decreased platelet count in patients receiving continuous veno-venous hemofiltration: a single-center retrospective study

BACKGROUND

A decreased platelet count may occur and portend a worse outcome in patients receiving continuous renal replacement therapy (CRRT). We aim to investigate the incidence of decreased platelet count and related risk factors in patients receiving CRRT.

METHODS

In this retrospective study, we screened all patients receiving continuous veno-venous hemofiltration (CVVH) at Jinling Hospital between November 2008 and October 2012. The patients were included who received uninterrupted CVVH for more than 72 h and had records of blood test for 4 consecutive days after ruling out pre-existing conditions that may affect the platelet count. Platelet counts before and during CVVH, illness severity, CVVH settings, and outcomes were analyzed.

RESULTS

The study included 125 patients. During the 3-day CVVH, 44.8% and 16% patients had a mild decline (20-49.9%) and severe decline (≥ 50%) in the platelet count,respectively; 37.6% and 16.0% patients had mild thrombocytopenia (platelet count 50.1-100 × 109/L) and severe thrombocytopenia (platelet count ≤ 50 × 10(9)/L), respectively. Patients with a severe decline in the platelet count had a significantly lower survival rate than patients without a severe decline in the platelet count (35.0% versus 59.0%, P=0.012), while patients with severe thrombocytopenia had a survival rate similar to those without severe thrombocytopenia (45.0% versus 57.1%, P=0.308). Female gender, older age, and longer course of the disease were independent risk factors for a severe decline in the platelet count.

CONCLUSIONS

A decline in the platelet count and thrombocytopenia are quite common in patients receiving CVVH. The severity of the decline in the platelet count rather than the absolute count during CVVH may be associated with hospital mortality. Knowing the risk factors for a severe decline in the platelet count may allow physicians to prevent such an outcome.

Thrombocytopenia is associated with acute respiratory distress syndrome mortality: an international study

Background

Early detection of the Acute Respiratory Distress Syndrome (ARDS) has the potential to improvethe prognosis of critically ill patients admitted to the intensive care unit (ICU). However, no reliable biomarkers are currently available for accurate early detection of ARDS in patients with predisposing conditions.

Objectives

This study examined risk factors and biomarkers for ARDS development and mortality in two prospective cohort studies.

Methods

We examined clinical risk factors for ARDS in a cohort of 178 patients in Beijing, China who were admitted to the ICU and were at high risk for ARDS. Identified biomarkers were then replicated in a second cohort of1,878 patients in Boston, USA.

Results

Of 178 patients recruited from participating hospitals in Beijing, 75 developed ARDS. After multivariate adjustment, sepsis (odds ratio [OR]:5.58, 95% CI: 1.70–18.3), pulmonary injury (OR: 3.22; 95% CI: 1.60–6.47), and thrombocytopenia, defined as platelet count <80×10³/µL, (OR: 2.67; 95% CI: 1.27–5.62)were significantly associated with increased risk of developing ARDS. Thrombocytopenia was also associated with increased mortality in patients who developed ARDS (adjusted hazard ratio [AHR]: 1.38, 95% CI: 1.07–1.57) but not in those who did not develop ARDS(AHR: 1.25, 95% CI: 0.96–1.62). The presence of both thrombocytopenia and ARDS substantially increased 60-daymortality. Sensitivity analyses showed that a platelet count of <100×10³/µLin combination with ARDS provide the highest prognostic value for mortality. These associations were replicated in the cohort of US patients.

Conclusions

This study of ICU patients in both China and US showed that thrombocytopenia is associated with an increased risk of ARDS and platelet count in combination with ARDS had a high predictive value for patient mortality.

Drug-Induced Thrombocytopenia in the Critically Ill

Background:Drugs are suspected when obvious causes of intensive care unit (ICU)-acquired thrombocytopenia have been excluded. It has been estimated that 10% to 25% of cases may be drug induced. Objectives: The objectives of this study were to evaluate the risk of thrombocytopenia associated with drug classes commonly used in the ICU. Methods: Data concerning patients admitted for more than 48 hours between 1997 and 2011 were extracted from a research-purpose database. Patients with thrombocytopenia within the first 72 hours of admission and with diagnoses or interventions considered strongly associated with thrombocytopenia were excluded. Drug exposures were compared and adjusted for confounders using conditional logistic regression. Results: A total of 238 cases were identified after exclusions. Each case was matched according to sex, age, admission year, and admission unit with 1 control. In univariate analysis, quinolones (odds ratio [OR] = 1.56; 95% CI = 1.01-2.40) and extended spectrum β-lactams (OR = 1.71; 95% CI = 1.00-2.93) were significantly associated with an increased risk of thrombocytopenia. After adjusting for confounders, exposure to quinolones was the only drug class with a statistically significant increase in risk of thrombocytopenia (OR = 1.697; 95% CI = 1.002-2.873; P = 0.049). Conclusion: In this study of ICU-acquired thrombocytopenia, we found no association between the exposures to several antibiotic classes, anticonvulsants, antiplatelet agents, nonsteroidal anti-inflammatory agents, and heparins and thrombocytopenia. As linezolid was not studied, no conclusions can be drawn concerning this agent. The statistically significant association between quinolones and thrombocytopenia warrants further investigation.

An overview of platelet indices and methods for evaluating platelet function in thrombocytopenic patients

Thrombocytopenia is associated with bleeding risk. However, in thrombocytopenic patients, platelet count does not correlate with bleeding risk and other factors are thus likely to contribute to this risk. This review presents currently available platelet-related markers available on automated haematology analysers and commonly used methods for testing platelet function. The test principles, advantages and disadvantages of each test are described. We also evaluate the current literature regarding the clinical utility of the test for prediction of bleeding in thrombocytopenia in haematological and oncological diseases. We find that several platelet-related markers are available, but information about the clinical utility in thrombocytopenia is limited. Studies support that mean platelet volume (MPV) can aid diagnosing the cause of thrombocytopenia and low MPV may be associated with bleeding in thrombocytopenia. Flow cytometry, platelet aggregometry and platelet secretion tests are used to diagnose specific platelet function defects. The flow cytometric activation marker P-selectin and surface coverage by the Cone-and-Plate[let] analyser predict bleeding in selected thrombocytopenic populations. To fully uncover the clinical utility of platelet-related tests, information about the prevalence of platelet function defects in thrombocytopenic conditions is required. Finally, knowledge of the performance in thrombocytopenic samples from patients is essential.

Thrombocytopenia in critically ill patients receiving thromboprophylaxis: frequency, risk factors, and outcomes

BACKGROUND

Thrombocytopenia is the most common hemostatic disorder in critically ill patients. The objective of this study was to describe the incidence, risk factors, and outcomes of thrombocytopenia in patients admitted to medical-surgical ICUs.

METHODS

Three thousand seven hundred forty-six patients in 67 centers were enrolled in a randomized trial in which unfractionated heparin was compared with low-molecular-weight heparin (LMWH) for thromboprophylaxis. Patients who had baseline platelet counts < 75 × 10(9)/L or severe coagulopathy at screening were excluded. We analyzed the risk of developing mild (100-149 × 10(9)/L), moderate (50-99 × 10(9)/L), and severe (< 50 × 109/L) thrombocytopenia during an ICU stay. We also assessed independent and time-varying predictors of thrombocytopenia and the effect of thrombocytopenia on major bleeding, transfusions, and death.

RESULTS

The incidences of mild, moderate, and severe thrombocytopenia were 15.3%, 5.1%, and 1.6%, respectively. The predictors of each category of thrombocytopenia were APACHE (Acute Physiology and Chronic Health Evaluation) II score, use of inotropes or vasopressors, and renal replacement therapy. The risk of moderate thrombocytopenia was lower in patients who received LMWH thromboprophylaxis but higher in surgical patients and in patients who had liver disease. Each category of thrombocytopenia was associated with subsequent bleeding and transfusions. Moderate and severe thrombocytopenia were associated with increased ICU and hospital mortality.

CONCLUSION

A high severity of illness, prior surgery, use of inotropes or vasopressors, renal replacement therapy, and liver dysfunction are associated with a higher risk of thrombocytopenia developing in the ICU, whereas LMWH thromboprophylaxis is associated with a lower risk. Patients who develop thrombocytopenia in the ICU are more likely to bleed, receive transfusions, and die.

Active exercise in critically ill adults affected by thrombocytopaenia

Introduction

Thrombocytopaenia (TCP), or low platelet count, is a haematological disorder that commonly occurs in critically ill patients and is defined as a platelet count below 100 000/μL. Patients are at higher risk of muscular atrophy and other complications after prolonged bed rest. This literature review aims to clarify the appropriateness of active exercise in critically ill adult patients with TCP.

Methods

A review of the literature was conducted using the following key words that are PubMed medical subheading (MeSH) terms: ‘critical illness’, ‘exercise therapy’, ‘manual therapy’, ‘physical therapy’, ‘physiotherapy’, ‘postoperative care’, ‘rehabilitation’, ‘thrombocytopenia’, and ‘thrombopenia’. The search was limited by publication date (2000 to 2013) and language (English only) in three main databases: PubMed, SCOPUS, and CINAHL.

Results

The key word searches found a total of 78 citations. Of these, only those meeting the inclusion criteria were selected after reading the title and abstract. Two studies were included after reading the full-texts. Exercise is used to treat muscular atrophy in critically ill adult patients, and rehabilitation plays an important role in the care pathway. Results of our analysis do not support evidence for or against exercise in critically ill adult patients with TCP; therefore, health professionals must pay close attention to the presence of signs of bleeding in these patients when proposing exercise.

Discussion

Surprisingly, no study was found that directly covered this issue. Aggressive exercise may not be appropriate in patients with very low platelet counts. On the other hand, critically ill patients are at high risk of muscular atrophy due to the forced bed rest, especially after complex surgery or in prolonged hospitalisation. Physiotherapists and those providing care must share their observations with the rest of the multidisciplinary team before treatment starts.

Conclusions

Active exercise in critically ill adult patients with severe TCP must be personalised and platelet count carefully monitored before proposing physical activity. Physical recovery can be challenging in critically ill adult patients, and it can be limited by severe TCP, mostly when bleeding is present.

Hematologic Complications

Critically ill patients are at high risk of developing various hematologic complications that may be present on admission or occur during their stay in the Intensive Care Unit (ICU). Often times the etiology of specific hematologic abnormalities is unclear and the diagnosis may be challenging due to the complexity of critically ill patients. This chapter will focus on diagnosis and management of the most commonly encountered hematologic problems in the critically ill such as anemia, neutropenia, thrombocytopenia, coagulopathy and thrombotic complications, with specific focus on diagnosis and management of these conditions.

Platelets: bridging hemostasis, inflammation, and immunity

Although the function of platelets in the maintenance of hemostasis has been studied in great detail, more recent evidence has highlighted a central role for platelets in the host inflammatory and immune responses. Platelets by virtue of their large numbers and their ability to rapidly release a broad spectrum of immunomodulatory cytokines, chemokines, and other mediators act as circulating sentinels. Upon detection of a pathogen, platelets quickly activate and begin to drive the ensuing inflammatory response. Platelets have the ability to directly modulate the activity of neutrophils (phagocytosis, oxidative burst), endothelium (adhesion molecule and chemokine expression), and lymphocytes. Due to their diverse array of adhesion molecules and preformed chemokines, platelets are able to adhere to leukocytes and facilitate their recruitment to sites of tissue damage or infection. Furthermore, platelets directly participate in the capture and sequestration of pathogens within the vasculature. Platelet-neutrophil interactions are known to induce the release of neutrophil extracellular traps (NETs) in response to either bacterial or viral infection, and platelets have been shown to internalize pathogens, sequestering them in engulfment vacuoles. Finally, emerging data indicate that platelets also participate in the host immune response by directly killing infected cells. This review will highlight the central role platelets play in the initiation and modulation of the host inflammatory and immune responses.

Risk factors and impact of major bleeding in critically ill patients receiving heparin thromboprophylaxis

PURPOSE

Bleeding frequently complicates critical illness and may have serious consequences. Our objectives are to describe the predictors of major bleeding and the association between bleeding and mortality in medical-surgical critically ill patients receiving heparin thromboprophylaxis.

METHODS

We prospectively studied patients from 67 intensive care units and six countries enrolled in a thromboprophylaxis trial (NCT00182143) comparing dalteparin with unfractionated heparin. Patients with trauma, orthopedic surgery or neurosurgery were excluded. Trained research coordinators used a validated tool to document bleeding, which underwent duplicate independent blinded adjudication. Major bleeding was defined as hypovolemic shock, bleeding into critical sites, requiring an invasive intervention or transfusion of at least two units of red blood cells, or associated with hypotension or tachycardia in the absence of other causes. Adjusted Cox proportional hazard regression analysis was used to identify major bleeding predictors and the association between bleeding and mortality.

RESULTS

Among 3,746 patients, bleeding occurred in 208 [5.6 %, 95 % confidence interval (CI) 4.9-6.3 %]. Time-dependent predictors were prolonged activated partial thromboplastin time [hazard ratio (HR) 1.10, 1.05-1.14 per 10 s increase], lower platelet count (HR 1.16, 1.09-1.24 per 50 × 10(9)/L decrease), therapeutic heparin (HR 3.26, 1.72-6.17), antiplatelet agents (HR 1.38, 1.02-1.88), renal replacement therapy (HR 1.75, 1.20-2.56), and recent surgery (HR 1.64, 1.01-2.65). Type of pharmacologic thromboprophylaxis was not associated with bleeding. Patients with bleeding had a higher risk of in-hospital death (HR 2.09, 1.69-2.57).

CONCLUSIONS

As major bleeding has modifiable risk factors and is associated with in-hospital mortality, strategies to mitigate these factors should be evaluated in critically ill patients.

Development of a daily mortality probability prediction model from Intensive Care Unit patients using a discrete-time event history analysis

As studies have pointed out, severity scores are imperfect at predicting individual clinical chance of survival. The clinical condition and pathophysiological status of these patients in the Intensive Care Unit might differ from or be more complicated than most predictive models account for. In addition, as the pathophysiological status changes over time, the likelihood of survival day by day will vary. Actually, it would decrease over time and a single prediction value cannot address this truth. Clearly, alternative models and refinements are warranted. In this study, we used discrete-time-event models with the changes of clinical variables, including blood cell counts, to predict daily probability of mortality in individual patients from day 3 to day 28 post Intensive Care Unit admission. Both models we built exhibited good discrimination in the training (overall area under ROC curve: 0.80 and 0.79, respectively) and validation cohorts (overall area under ROC curve: 0.78 and 0.76, respectively) to predict daily ICU mortality. The paper describes the methodology, the development process and the content of the models, and discusses the possibility of them to serve as the foundation of a new bedside advisory or alarm system.

Ticagrelor reduces neutrophil recruitment and lung damage in abdominal sepsis

Abstract Platelets play an important role in abdominal sepsis and P2Y12 receptor antagonists have been reported to exert anti-inflammatory effects. Herein, we assessed the impact of platelet inhibition with the P2Y12 receptor antagonist ticagrelor on pulmonary neutrophil recruitment and tissue damage in a model of abdominal sepsis. Wild-type C57BL/6 mice were subjected to cecal ligation and puncture (CLP). Animals were treated with ticagrelor (100 mg/kg) or vehicle prior to CLP induction. Edema formation and bronchoalveolar neutrophils as well as lung damage were quantified. Flow cytometry was used to determine expression of platelet-neutrophil aggregates, neutrophil activation and CD40L expression on platelets. CLP-induced pulmonary infiltration of neutrophils at 24 hours was reduced by 50% in ticagrelor-treated animals. Moreover, ticagrelor abolished CLP-provoked lung edema and decreased lung damage score by 41%. Notably, ticagrelor completely inhibited formation of platelet-neutrophil aggregates and markedly reduced thrombocytopenia in CLP animals. In addition, ticagrelor reduced platelet shedding of CD40L in septic mice. Our data indicate that ticagrelor can reduce CLP-induced pulmonary neutrophil recruitment and lung damage suggesting a potential role for platelet antagonists, such as ticagrelor, in the management of patients with abdominal sepsis.

Clinical and biologic features of patients suspected or confirmed to have heparin-induced thrombocytopenia in a cardiothoracic surgical ICU

BACKGROUND

The diagnosis of heparin-induced thrombocytopenia (HIT) is problematic in the surgical ICU, as there are multiple potential explanations for thrombocytopenia. We conducted a study to assess the incidence, clinical presentation, and outcome of HIT in a cardiothoracic surgical ICU.

METHODS

From January 2005 to December 2010, all patients with suspicion of HIT were prospectively identified, and data were collected retrospectively. Detection of anti-PF4/heparin antibodies and functional assays were systematically performed.

RESULTS

During the study period, 5,949 patients were admitted to the ICU (2,751 after cardiac surgery and 3,198 after thoracic surgery), of whom 101 were suspected to have HIT(1.7% [95% CI, 1.4%-2.0%]). Suspicion of HIT occurred at a median of 5 (4-9) days after ICU admission. Diagnosis was confirmed in 28 of 5,949 patients (0.47% [95% CI, 0.33%-0.68%]).Thrombosis was detected in 14 patients with HIT (50%) and in 12 patients without HIT (16%)( P 5 .0006). After receiver operating characteristic analysis (area under curve 5 0.78 0.06),a 4Ts score ≥ 5 had a sensitivity of 86% and a specificity of 70%. Course of platelet count was similar between the two groups. Six patients (21%) with HIT and 20 (27%) without died( P 5 .77).

CONCLUSIONS

Even with a prospective platelet monitoring protocol, suspicion for HIT arose in <2% of patients in a cardiothoracic ICU. Most were found to have other causes of thrombocytopenia,with HIT confirmed in 28 of 101 suspected cases (0.47% of all patients in the ICU). The 4Ts score may have value by identifying patients who should have laboratory testing performed.The mortality of patients with HIT was not different from other very ill thrombocytopenic patients in the ICU.

Diagnosis and treatment of coagulopathy following percutaneous cryoablation of liver tumors: experience in 372 patients

Coagulopathy after liver cryoablation was first reported many years ago; the cause is local platelet trapping and destruction within the margin of the cryolesion. However, the prognosis and therapeutic effects of coagulopathy remain unclear. This study retrospectively reviewed clinical data from 372 patients (525 sessions) who underwent liver cryoablation in our hospital during the past 4.5 years. Small tumors (major diameter < 6 cm) were treated with a single complete ablation; massive tumors (major diameter 6-10 cm or >10 cm) were divided into two or three parts that were dealt with in turn. Platelet counts decreased to an average of (46.12 ± 68.13) × 10(9)/L after each session of cryoablation. The decline was most evident in patients with high pretreatment platelet counts, while those with low pretreatment counts had the highest risk of coagulopathy. Change in platelet count was not correlated with the diameter of the tumor. Slight coagulopathy (platelet count (70-100) × 10(9)/L) can resolve without treatment within 1 week and administration of recombinant human interleukin-11 can assist recovery from severe coagulopathy (platelet count < 70 × 10(9)/L).

The evaluation of sequential platelet counts has prognostic value for acute kidney injury patients requiring dialysis in the intensive care setting

OBJECTIVE

To evaluate the prognostic value of platelet counts in acute kidney injury patients requiring renal replacement therapy.

METHODS

This prospective cohort study was performed in three tertiary-care hospitals. Platelet counts were obtained upon admission to the intensive care unit and during the first week of renal replacement therapy on days 1, 3, 5 and 7. The outcome of interest was the hospital mortality rate. With the aim of minimizing individual variation, we analyzed the relative platelet counts on days 3, 5, 7 and at the point of the largest variation during the first week of renal replacement therapy. Logistic regression analysis was used to test the prognostic value of the platelet counts.

RESULTS

The study included 274 patients. The hospital mortality rate was 62%. The survivors had significantly higher platelet counts upon admission to the intensive care unit compared to the non-survivors [175.5×10(3)/mm(3) (108.5-259×10(3)/mm(3)) vs. 148×10(3)/mm(3) (80-141×10(3)/mm(3))] and during the first week of renal replacement therapy. The relative platelet count reductions were significantly associated with a higher hospital mortality rate compared with the platelet count increases (70% vs. 44% at the nadir, respectively). A relative platelet count reduction >60% was significantly associated with a worse outcome (mortality rate=82.6%). Relative platelet count variations and the percentage of reduction were independent risk factors of hospital mortality during the first week of renal replacement therapy.

CONCLUSION

Platelet counts upon admission to the intensive care unit and at the beginning of renal replacement therapy as well as sequential platelet count evaluation have prognostic value in acute kidney injury patients requiring renal replacement therapy.

How to approach thrombocytopenia

Thrombocytopenia is a common hematologic finding with variable clinical expression. A low platelet count may be the initial manifestation of infections such as HIV and hepatitis C virus or it may reflect the activity of life-threatening disorders such as the thrombotic microangiopathies. A correct identification of the causes of thrombocytopenia is crucial for the appropriate management of these patients. In this review, we present a systematic evaluation of adults with thrombocytopenia. The approach is clearly different between outpatients, who are frequently asymptomatic and in whom we can sometimes indulge in sophisticated and relatively lengthy investigations, and the dramatic presentation of acute thrombocytopenia in the emergency department or in the intensive care unit, which requires immediate intervention and for which only a few diagnostic tests are available. A brief discussion of the most common etiologies seen in both settings is provided.

Sequential organ failure assessment (SOFA) scores differ between genders in a sepsis cohort: cause or effect?

BACKGROUND

Controversy exists regarding the influence of gender on sepsis events and outcome. Epidemiological data from other countries may not always apply to local circumstances. The aim of this study was to identify gender differences in patient characteristics, treatment, and outcome related to the occurrence of sepsis at admission to the ICU.

METHODS

A prospective observational cohort study on patients admitted to the ICU over a 3-year period fulfilling sepsis criteria during the first 24 hours. Demographic data, APACHE II score, SOFA score, TISS 76, aetiology, length of stay (LOS), mortality rate, and aspects of treatment were collected and then analysed with respect to gender differences.

RESULTS

There were no gender-related differences in mortality or length of stay. Early organ dysfunction assessed as SOFA score at admission was a stronger risk factor for hospital mortality for women than for men. This discrepancy was mainly associated with the coagulation sub-score. CRP levels differed between genders in relation to hospital mortality. Infection from the abdominopelvic region was more common among women, whereas infection from skin or skin structures were more common in men.

CONCLUSION

In this cohort, gender was not associated with increased mortality during a 2-year follow-up period. SOFA score at ICU admission was a stronger risk factor for hospital mortality for women than for men. The discrepancy was mainly related to the coagulation SOFA sub-score. Together with differences in CRP levels this may suggest differences in inflammatory response patterns between genders.