Evaluation of the Association of Platelet Count, Mean Platelet Volume, and Platelet Transfusion With Intraventricular Hemorrhage and Death Among Preterm Infants

Most major bleeds in preterm infants occur in the absence of severe thrombocytopenia: an observational cohort study

OBJECTIVE

To describe the incidence of major bleeds according to different platelet counts in very preterm infants, and to explore whether this association is influenced by other risk factors for bleeding.

DESIGN

Observational cohort study.

SETTING

A Dutch tertiary care neonatal intensive care unit.

PATIENTS

All consecutive infants with a gestational age at birth <32 weeks admitted between January 2004 and July 2022.

EXPOSURE

Infants were stratified into nine groups based on their nadir platelet count (×109/L) during admission (<10, 10-24, 25-49, 50-99, 100-149, 150-199, 200-249, 250-299 and ≥300), measured before the diagnosis of a major bleed and before any platelet transfusion was administered.

MAIN OUTCOME MEASURE

Incidence of major bleeds during admission. Logistic regression analysis was used to quantify the relationship between nadir platelet count and incidence of major bleeds.

RESULTS

Among 2772 included infants, 224 (8%) developed a major bleed. Of the infants with a major bleed, 92% (206/224) had a nadir platelet count ≥50×109/L. The incidence of major bleeds was 8% among infants with and without severe thrombocytopenia (platelet count <50×109/L), 18/231 (95% CI 5 to 12) and 206/2541 (95% CI 7 to 9), respectively. Similarly, after adjustment for measured confounders, there was no notable association between nadir platelet counts below versus above 50×109/L and the occurrence of major bleeds (OR 1.09, 95% CI 0.61 to 1.94).

CONCLUSION

In very preterm infants, the vast majority of major bleeds occur in infants without severe thrombocytopenia.

The causal relationship between blood cell indices and 28-day mortality in sepsis: a retrospective study and bidirectional Mendelian randomization analysis

BACKGROUND

Despite emerging evidence linking blood cell indices (BCIs) to sepsis mortality, the inconsistency of observational studies obscures the clarity of these associations. This study aims to clarify the causal influence of BCIs on 28-day mortality rates in sepsis patients.

METHODS

Utilizing univariable and multivariable Mendelian randomization (MR) analyses, we examined the impact of BCIs on sepsis mortality by analyzing data from extensive genome-wide association studies. The inverse-variance weighted (IVW) method was our primary analytic tool, complemented by several robustness checks to mitigate pleiotropy, including weighted median, mode-based estimates, MR-Egger regression, and MR-PRESSO. Subsequently, we conducted a retrospective study to further explore the correlation between platelet indices and 28-day mortality of sepsis using real-world data.

RESULTS

Our findings highlight a significant causal relationship between platelet distribution width (PDW) and 28-day mortality in sepsis, with the univariable Mendelian randomization approach yielding an odds ratio of 1.12 (95% CI, 1.06-1.26; P < 0.05). Multivariable analysis further substantiated PDW's robust association with mortality risk (OR 1.23; 95% CI, 1.03-1.48; P < 0.05). Conversely, our analysis did not uncover significant correlations between the genetic predispositions to other BCIs-including red blood cell count, erythrocyte distribution width, platelet count, mean platelet volume, white blood cell count, neutrophil count, neutrophil percentage, lymphocyte count, and lymphocyte percentage-and 28-day mortality in sepsis. Additionally, an inverse MR analysis did not establish a causal impact of 28-day mortality in sepsis on PDW (OR 1.00; 95% CI, 1.00-1.07; P = 0.29). Moreover, a similar result was observed in the retrospective study.

CONCLUSIONS

The study underscores the independent causal role of PDW in predicting 28-day mortality in sepsis, suggesting its potential utility in early patient assessment, risk stratification, and tailoring of therapeutic interventions.

Development and validation of a diagnostic prediction model for severe periventricular-intraventricular hemorrhage in newborns: insights from a retrospective analysis utilizing the MIMIC-III database

OBJECTIVE

Periventricular-intraventricular hemorrhage is the most common type of intracranial bleeding in newborns, especially in the first 3 days after birth. Severe periventricular-intraventricular hemorrhage is considered a progression from mild periventricular-intraventricular hemorrhage and is often closely associated with severe neurological sequelae. However, no specific indicators are available to predict the progression from mild to severe periventricular-intraventricular in early admission. This study aims to establish an early diagnostic prediction model for severe PIVH.

METHOD

This study was a retrospective cohort study with data collected from the MIMIC-III (v1.4) database. Laboratory and clinical data collected within the first 24 h of NICU admission have been used as variables for both univariate and multivariate logistic regression analyses to construct a nomogram-based early prediction model for severe periventricular-intraventricular hemorrhage and subsequently validated.

RESULTS

A predictive model was established and represented by a nomogram, it comprised three variables: output, lowest platelet count and use of vasoactive drugs within 24 h of NICU admission. The model's predictive performance showed by the calculated area under the curve was 0.792, indicating good discriminatory power. The calibration plot demonstrated good calibration between observed and predicted outcomes, and the Hosmer-Lemeshow test showed high consistency (p = 0.990). Internal validation showed the calculated area under a curve of 0.788.

CONCLUSIONS

This severe PIVH predictive model, established by three easily obtainable indicators within the NICU, demonstrated good predictive ability. It offered a more user-friendly and convenient option for neonatologists.

Separation of platelets by size in a microfluidic device based on controlled incremental filtration

The significant biological and functional differences between small and large platelets suggested by recent studies could have profound implications for transfusion medicine. However, investigating the relationship between platelet size and function is challenging because separating platelets by size without affecting their properties is difficult. A standard approach is centrifugation, but it inevitably leads to premature activation and aggregation of separated platelets. This paper describes the development and validation of a microfluidic device based on controlled incremental filtration (CIF) for separating platelets by size without the cell damage and usability limitations associated with centrifugation. Platelet samples derived from whole blood were used to evaluate the dependence of the CIF device separation performance on design parameters and flow rate, and to compare the properties of PLT fractions generated by the CIF device with those produced using a centrifugation protocol in a split-sample study. This was accomplished by quantifying the platelet size distribution, mean platelet volume (MPV), platelet-large cell ratio (P-LCR) and platelet activation before and after processing for all input and output samples. The 'large platelet' fractions produced by the CIF device and the centrifugation protocol were essentially equivalent (no significant difference in MPV and P-LCR). Platelets in the 'small platelet' fraction produced by the CIF device were significantly smaller than those produced by centrifugation (lower MPV and P-LCR). This was because the CIF 'small platelet' fraction was contaminated by much fewer large platelets (∼2-times lower recovery of >12 fL platelets) and retained the smallest platelets that were discarded by the centrifugation protocol. There was no significant difference in platelet activation between the two methods. However, centrifugation required a substantial amount of additional anticoagulant to prevent platelet aggregation during pelleting. Unlike centrifugation, the CIF device offered continuous, flow-through, single-step processing that did not cause platelet aggregation. Such a capability has the potential to accelerate the basic studies of the relationship between platelet size and function, and ultimately improve transfusion practice, particularly in the pediatric setting, where the need for low-volume, high-quality platelet transfusions is most urgent.

Transfusion of Adult, but Not Neonatal, Platelets Promotes Monocyte Trafficking in Neonatal Mice

BACKGROUND

Thrombocytopenia is common in preterm neonates. Platelet transfusions are sometimes given to thrombocytopenic neonates with the hope of reducing the bleeding risk, however, there are little clinical data to support this practice, and platelet transfusions may increase the bleeding risk or lead to adverse complications. Our group previously reported that fetal platelets expressed lower levels of immune-related mRNA compared with adult platelets. In this study, we focused on the effects of adult versus neonatal platelets on monocyte immune functions that may have an impact on neonatal immune function and transfusion complications.

METHODS

Using RNA sequencing of postnatal day 7 and adult platelets, we determined age-dependent platelet gene expression. Platelets and naive bone marrow-isolated monocytes were cocultured and monocyte phenotypes determined by RNA sequencing and flow cytometry. An in vivo model of platelet transfusion in neonatal thrombocytopenic mice was used in which platelet-deficient TPOR (thrombopoietin receptor) mutant mice were transfused with adult or postnatal day 7 platelets and monocyte phenotypes and trafficking were determined.

RESULTS

Adult and neonatal platelets had differential immune molecule expression, including Selp. Monocytes incubated with adult or neonatal mouse platelets had similar inflammatory (Ly6Chi) but different trafficking phenotypes, as defined by CCR2 and CCR5 mRNA and surface expression. Blocking P-sel (P-selectin) interactions with its PSGL-1 (P-sel glycoprotein ligand-1) receptor on monocytes limited the adult platelet-induced monocyte trafficking phenotype, as well as adult platelet-induced monocyte migration in vitro. Similar results were seen in vivo, when thrombocytopenic neonatal mice were transfused with adult or postnatal day 7 platelets; adult platelets increased monocyte CCR2 and CCR5, as well as monocyte chemokine migration, whereas postnatal day 7 platelets did not.

CONCLUSIONS

These data provide comparative insights into adult and neonatal platelet transfusion-regulated monocyte functions. The transfusion of adult platelets to neonatal mice was associated with an acute inflammatory and trafficking monocyte phenotype that was platelet P-sel dependent and may have an impact on complications associated with neonatal platelet transfusions.