Mean platelet volume during coagulase-negative staphylococcal sepsis in neonates

Platelets in pediatric and neonatal sepsis: novel mediators of the inflammatory cascade

Sepsis, a dysregulated host response to infection, has been difficult to accurately define in children. Despite a higher incidence, especially in neonates, a non-specific clinical presentation alongside a lack of verified biomarkers has prevented a common understanding of this condition. Platelets, traditionally regarded as mediators of haemostasis and thrombosis, are increasingly associated with functions in the immune system with involvement across the spectrum of innate and adaptive immunity. The large number of circulating platelets (approx. 150,000 cells per microlitre) mean they outnumber traditional immune cells and are often the first to encounter a pathogen at a site of injury. There are also well-described physiological differences between platelets in children and adults. The purpose of this review is to place into context the platelet and its role in immunology and examine the evidence where available for its role as an immune cell in childhood sepsis. It will examine how the platelet interacts with both humoral and cellular components of the immune system and finally discuss the role the platelet proteome, releasate and extracellular vesicles may play in childhood sepsis. This review also examines how platelet transfusions may interfere with the complex relationships between immune cells in infection. IMPACT: Platelets are increasingly being recognised as important "first responders" to immune threats. Differences in adult and paediatric platelets may contribute to differing immune response to infections. Adult platelet transfusions may affect infant immune responses to inflammatory/infectious stimuli.

Mean platelet volume in preterm: a predictor of early onset neonatal sepsis

Background: Early onset sepsis (EOS) is potentially life-threatening problem especially in preterm. EOS diagnosis is challenging due to its non-specific signs and laboratory tests. Mean platelet volume (MPV) has been used as predictor of many inflammatory diseases.Objectives: To assess the correlation between serial MPV measurement and EOS occurrence in preterm infants and to determine MPV effectiveness in combination with C reactive protein (CRP) to diagnose EOS and mortality prediction.Methods: The study was carried out on 95 preterm infants with antenatal risk factor for EOS. Blood samples were taken for complete blood count (CBC) including MPV evaluated at birth (cord blood) and at 72 h of life. CRP analyzed on days 1 and 3, subsequently patients were identified in two groups: sepsis (n = 28) and no-sepsis (n = 67).Results: MPV was significantly higher on both day 1 (10.23 ± 0.92) fl and day 3 (10.77 ± 1.16) fL in the sepsis group compared with no-sepsis (8.11 ± 0.29) fl and (8.53 ± 0.42) fl, respectively. MPV of 8.6 fL was identified as cut off value in patients probably resulting in sepsis with a sensitivity of 97.14% and a specificity of 100%. MPV of 10.4 fl was determined as cut off value in patients possibly resulting in death with a sensitivity of 70% and a specificity of 82.5%. The combination of both MPV and CRP on day 1 resulted in improving performance of MPV with higher negative predictive value (93.1%) and higher sensitivity (80%).Conclusion: High cord blood and day 3 MPV can be used as surrogate marker for prediction of EOS and associated mortality in preterm neonates.

Platelet indices in neonatal sepsis: A review

Thrombocytopenia is a common hematological abnormality in neonates with sepsis. The autoanalyzers now-a-days readily provide platelet indices along with platelet counts without any additional cost. However these indices are not given proper weightage often. The important platelet indices available for clinical utility include mean platelet volume (MPV), platelet distribution width and plateletcrit that are related to morphology and proliferation kinetics of platelets. Studies in adult patients reported their role in the diagnosis of severe sepsis and prognosis of adverse clinical outcomes including mortality. Abnormal MPV can aid diagnosing the cause of thrombocytopenia. Low MPV associated with thrombocytopenia has been found to result in clinical bleeding. Other indices, however, are less studied. The studies addressing the importance of these platelet indices in neonatal sepsis are limited. The current review gives an overview of potential utility of important platelet indices in neonatal sepsis.

Mean platelet volume and uric acid levels in neonatal sepsis

OBJECTIVES

To determine the role of mean platelet volume (MPV) and uric acid levels in the diagnosis of neonatal sepsis (NS).

METHODS

A total of 146 newborns with suspected NS were prospectively included in the study and infants without NS (n = 142) were assigned as controls. The patients were divided into three groups: Group I (n = 64): clinical NS, Group II (n = 82): culture-proven NS, and Group III (n = 142): healthy controls.

RESULTS

The patients in Group II had the highest C-reactive protein (CRP) levels (54.6 ± 5.4 mg/L), lowest platelet counts (199,329 ± 135,952/mm(3)) and lowest uric acid levels (2.6 ± 1.8 mg/dL) when compared to Groups I and III (p < 0.05, for all comparisons). MPV values were higher in Group I (10.6 ± 1.1 fL) and Group II (10.4 ± 0.9 fL) when compared to Group III (9.2 ± 1.2 fL) (p = 0.001), although there was no difference between Groups I and II. Area under curve (AUC) values for CRP, MPV, and uric acid were 0.92 (p = 0.001), 0.76 (p = 0.001) and 0.28 (p = 0.001), respectively. The diagnostic cut-off values for CRP and MPV were 9.5 mg/dL and 10.4 fL. Sensitivity and specificity of MPV in NS were 54 % and 82 % respectively. When combined with CRP its sensitivity and specificity increased to 89 % and 79 % respectively.

CONCLUSIONS

The combined use of CRP and MPV should be considered in the early diagnosis of NS, but uric acid levels may only be utilized as an additional tool to support diagnosis. CRP is shown to be more sensitive and specific than MPV and uric acid in diagnosing neonatal sepsis.

[Thrombopenia and the nature of the microorganism in infected critically ill children]

BACKGROUND

Thrombopenia is correlated with sepsis and mortality in pediatric intensive care units. The purpose of this study was to find an association between thrombopenia and the microorganism type to guide the choice of empiric antibiotic therapy in infected critically ill children.

MATERIALS AND METHODS

We conducted a prospective descriptive study, including all newborns, infants, and children admitted to a pediatric surgical intensive care unit from 1st January to 31st December 2009. We identified patients who developed an infection and/or thrombopenia (platelet count less than 100,000/mm(3)) during hospitalization.

RESULTS

One hundred ninety-seven patients were included (57 newborns, 41 infants, 99 children). Ninety patients developed 100 infectious episodes during the study period. Of the 57 newborns enrolled in the study, 31 (54%) developed 37 infections. Seventy-six microorganisms (55 Gram-negative bacilli [GNB], 17 Gram-positive cocci, two Gram-negative cocci, two fungal pathogens) were identified during 65 infectious episodes in 55 patients. Thirty-four episodes of thrombopenia were observed in 30 patients. Thrombopenia was observed only in infected patients (P<0.001). Thrombopenia was associated with infections caused by GNB (26/28 vs 20/37, P=0.001) and by Klebsiella (16/28 vs 6/37, P=0.001) and may be associated with infections caused by GNB producing extended-spectrum beta-lactamases (P=0.07). Gram-positive cocci infections were correlated to the non-occurrence of thrombopenia (P=0.02). Postoperative peritonitis was also significantly associated with thrombopenia (P=0.03). The mortality rate in our patients was 12.7% (22.8% in neonates). There was an association between thrombopenia and death in univariate analysis (11/25 vs 19/172, P<0.001). Multivariate logistic regression analysis did not confirm thrombopenia as an independent predictive factor of mortality in children.

CONCLUSION

Because of the relatively high proportion of resistant GNB, an empiric antibiotic therapy combining a carbapenem and an aminoglycoside may be indicated in infected critically ill children developing thrombopenia.

An increase in mean platelet volume after admission is associated with higher mortality in critically ill patients

Background

Platelet activation and consumption are common in critically ill patients and are associated with poorer prognosis. Mean platelet volume is a simple surrogate for platelet activation, with higher MPV being associated with worse clinical condition on a large array of clinical diagnoses. We therefore aimed to investigate associations between changes in platelet count and mean platelet volume (MPV) with prognosis and inflammatory cytokine values in critically ill patients.

Methods

This study prospectively included 84 critically ill patients. Patients were stratified into four groups according to proportional changes in MPV (ΔMPV_24h) and platelet count (ΔPlat_24h) in the first 24 hours after admission. Mortality between groups was compared using the χ² test. Logistic regression was performed using hospital mortality as outcome and Simplified Acute Physiology Score (SAPS 3), ΔPlat_24h and ΔMPV_24h as covariates. Concentrations of the following inflammatory mediators were measured using Miliplex® technology: IL1β, IL6, IL8, IL10, epidermal growth factor, vascular endothelial growth factor, TNFα and IFNα. Cytokine concentrations were compared between groups using the Kruskal-Wallis test with Bonferroni correction.

Results

Patients in whom MPV increased and platelet count decreased had higher mortality rates (46%). According to logistic regression, ΔMPV_24h was independently associated with increased mortality (OR 1.28 per 1% increase; 95% CI 1.08 to 1.48). No strong associations between inflammatory mediators and changes in MPV and platelet count were found.

Conclusion

An increase in MPV after admission to an ICU is independently associated with higher hospital mortality.

Mean platelet volume in neonatal sepsis

BACKGROUND

The aim of this study was to investigate any changes in mean platelet volume (MPV) in patients with neonatal sepsis (NS).

METHODS

Subjects were stratified into two groups: proven sepsis (Group 1a) and clinical sepsis (Group 1b). The control group (Group 2) consisted of healthy newborns matched for gestational age and birth weight.

RESULTS

A total of 100 patients with NS (35 with proven sepsis and 65 with clinical sepsis) and 50 healthy controls were enrolled. A comparison of markers of sepsis obtained at baseline revealed white blood cell count (WBC), C-reactive protein (CRP), interleukin-6 (IL-6), and MPV levels to be significantly higher in newborns with sepsis compared to healthy controls (P = 0.01, <0.001, <0.001, and 0.001, respectively). Mean baseline serum levels of CRP and MPV were significantly higher in Group 1a compared to Group 1b (P = 0.003, P = 0.007, respectively), whereas the difference between group with regards to baseline serum levels of IL-6 and platelet count was statistically insignificant (P = 0.14, P = 0.28, respectively).

CONCLUSION

This is the first study to demonstrate a statistically significant difference with regard to baseline MPV values between patients with sepsis (proven or clinical) and healthy controls.

Is a small platelet mass associated with intraventricular hemorrhage in very low-birth-weight infants?

OBJECTIVE

We sought to determine whether, among very low-birth-weight (VLBW) neonates, the platelet mass was associated with common perinatal factors, and whether a low platelet mass in the first days following birth was associated with a higher incidence and/or severity of intraventricular hemorrhage (IVH).

STUDY DESIGN

This was a cross-sectional, retrospective cohort analysis of VLBW infants admitted to a level 3 neonatal intensive care unit from June 2003 to July 2006, n=408. Platelet mass was calculated and recorded on the day of birth and for 2 consecutive days thereafter. All neonates had a screening cranial sonogram on day 4 of life. Statistical analysis included analysis of variance and Mann-Whitney U-test.

RESULT

Neonates born to mothers with pre-eclampsia had a smaller platelet mass (1921 fl/nl ± 603 vs 2297 fl/nl ± 747; P<0.01). The same was found among neonates with intrauterine growth restriction (IUGR). In contrast, neonates born after histological chorioamnionitis had a larger platelet mass (2400 fl/nl ± 749 vs 2036 fl/nl ± 674; P<0.01). No effect of platelet mass, measured on the day of birth, was observed related the outcomes of IVH, severe IVH or death. However, those with a platelet mass <10th percentile on the 2 subsequent days following birth were more likely to have severe IVH or death.

CONCLUSION

Among VLBW neonates, pre-eclampsia and IUGR are associated with a lower platelet mass, owing to their effect on platelet count. Histological chorioamnionits is associated with a larger platelet mass. A mass <10th percentile on the days following birth was associated with severe IVH and/or death, but it remains unclear whether this is a cause of, or an effect of, the IVH.

Is thrombocytopenia suggestive of organism-specific response in neonatal sepsis?

BACKGROUND

It is controversial whether thrombocytopenia is suggestive of one (or more) causative agents of neonatal sepsis: a low platelet count has been related in turn to Gram-positive, Gram-negative or fungal sepsis.

METHODS

A retrospective, cohort study on 514 very low-birthweight (VLBW) neonates admitted over a 9 year period to a large tertiary neonatal intensive care unit (NICU) in Italy was carried out. Through database search, data on platelet counts, sepsis, clinical course, and microbiological culture were collected and analyzed. Statistical analysis was performed to look for significant association between thrombocytopenia and sepsis caused by different (Gram-positive, Gram-negative or fungal) organisms.

RESULTS

Sepsis diagnosed on microbiological criteria occurred in 197 of 514 VLBW neonates (38.3%), and thrombocytopenia (at least one finding of platelet count <80,000/mm(3)) was detected in 34 (17.2%) of the 197 septic infants. Thrombocytopenia occurred in 10 of 51 neonates with fungal sepsis (19.6%), and in 24 of 146 with bacterial sepsis (16.4%; P = 0.37). The difference was not significant when clustering for sepsis caused by Gram-positive (nine thrombocytopenic of 51 with Gram-positive sepsis, 17.6%; P = 0.40) and Gram-negative organisms (15/95, 15.7%; P = 0.22), or when considering only coagulase-negative Staphylococcus sepsis (6/37, 16.2%; P = 0.25).

CONCLUSIONS

In contrast with previous reports, thrombocytopenia might not be an organism-specific marker of sepsis. Caution should be maintained in relating a low platelet count to any infectious agent (or group of agents) in preterm VLBW neonates.

Evaluation and treatment of severe and prolonged thrombocytopenia in neonates

Thrombocytopenia is one of the most common hematologic problems in the neonatal intensive care unit (NICU). Despite its prevalence,several basic pathophysiologic questions remain unanswered. For instance, there is a lack of evidence-based guidelines for treatment,and the kinetic mechanisms (decreased platelet production,increased platelet consumption, or sequestration) responsible for most varieties of neonatal thrombocytopenia are not well defined.Moreover, a clear correlation between degree of thrombocytopenia and the resulting bleeding risk has not been demonstrated, and no transfusion-trigger studies have been conducted in neonates. As a consequence of these deficiencies in knowledge, there is great variability in platelet transfusion practices among NICUs. This article presents an overview of the evaluation of a neonate with severe thrombocytopenia and a review of current and projected therapeutic options.

Platelet count and sepsis in very low birth weight neonates: is there an organism-specific response?

OBJECTIVE

Thrombocytopenia is commonly observed in very low birth weight (VLBW) neonates with sepsis. Specific platelet responses to different infectious agents have not been extensively characterized. The objectives of this study were to examine platelet counts and platelet indices in preterm neonates with culture-proven sepsis to determine if there are organism-specific platelet responses.

STUDY DESIGN

We analyzed a cohort of all VLBW neonates (birthweight <1500 g) born over a 4-year period and admitted to a single level III neonatal intensive care unit (N = 943). Thrombocytopenia was defined as a platelet count <100,000/mm(3). Platelet count, nadir, duration of thrombocytopenia, and mean platelet volume (MPV) were examined during episodes of culture-proven sepsis. Analysis of variance, Kruskal-Wallis, Mann-Whitney U, and chi(2) tests were used to compare groups, and data are expressed as mean +/- standard deviation.

RESULTS

Sepsis was diagnosed in 154 (16%) of 943 patients in the study population. Of the sepsis episodes, 54% were associated with thrombocytopenia and 61% with an elevation in MPV. Infections were grouped by organism type: Gram-positive bacteria (117/154, 76%), Gram-negative bacteria (24/154, 16%), and fungi (13/154, 8%). When compared with patients with Gram-positive sepsis, those with Gram-negative or fungal sepsis had a significantly lower initial platelet count, a lower platelet nadir, a higher incidence of thrombocytopenia, and a greater duration of thrombocytopenia. The decrease in platelet count from baseline was also significantly less in the Gram-positive infections than in the fungal infections. Although there was an overall increase in MPV from baseline, there were no differences between groups.

CONCLUSIONS

In our population of VLBW infants, sepsis is frequently associated with thrombocytopenia and an elevation in MPV. However, fungal and Gram-negative pathogens are associated with a lower platelet count and more prolonged thrombocytopenia compared with Gram-positive pathogens. We conclude that common pathogens causing sepsis have different effects on platelet kinetics.

Mechanisms underlying thrombocytopenia in the neonatal intensive care unit

Thrombocytopenia is one of the most common hematological problems among neonates in the neonatal intensive care unit (NICU), but in the majority of cases the kinetic mechanism responsible is unclear. This review focuses on both traditional and innovative methods used to evaluate the mechanisms responsible for thrombocytopenia in neonates, and analyzes the data generated from those methods.

CONCLUSION

Results of studies using new methods for evaluating thrombocytopenia, coupled with recent descriptions of marrow megakaryocyte mass, suggest that decreased platelet production complicates most cases of thrombocytopenia among neonates in the NICU.

Evaluation and treatment of thrombocytopenia in the neonatal intensive care unit

Thrombocytopenia is a very frequent problem among sick neonates, affecting up to 35% of all infants admitted to the NICU. Although multiple clinical conditions have been causally associated with neonatal thrombocytopenia, the cause of the thrombocytopenia is unclear in up to 60% of affected neonates. This article provides neonatologists with a practical approach to the thrombocytopenic neonate, with an emphasis on conditions that could be life-threatening or could have significant implications for further pregnancies. An overview of the current therapeutic modalities is also presented, including a discussion of the possible use of recombinant thrombopoietic cytokines to treat certain groups of thrombocytopenic neonates.

Mean Platelet Volume in Thrombocytopenic, Preterm Infants

We evaluated the use of mean platelet volume (MPV) as a reliable indicator of bacteremia in neonates. We first established normal MPV values in very low birth weight neonates (< 1 kg and ≥ 1 kg < 1.8 kg, respectively) in the first 47 days of life. We conclude that MPV is not a reliable predictor of sepsis. However, one subset of thrombocytopenic neonates, with birth weights ≥ 1 kg < 1.8 kg was identified with significantly increased MPV (P < 0.05) compared to the age-matched control. In this group, the thrombocytopenia was not associated with sepsis, and the etiology of the decreased platelet count remained to be determined.