Qualitative and quantitative changes in platelets after coronary-artery bypass surgery may help identify thrombotic complications and infections

Assessment of the utility of platelet indices to diagnose clinical benign prostatic hyperplasia in dogs

Introduction

Platelet indices changes in severely ill people and in dogs with inflammation are compatible findings. This study aimed to compare platelet indices between dogs with clinical benign prostatic hyperplasia (BPH) and healthy controls. Additionally, to determine whether there is a correlation between the relative prostatic size (S _rel) and the platelet indices in BPH dogs.

Methods

Thirty-five adult intact male dogs of different breeds were allocated to the experimental groups: dogs with clinical BPH (groups A; n = 24; median age of 6 years; the median weight of 8.50 kg) and healthy dogs (group B; n = 11; median age 5.50 years; the median weight of 7.00 kg) based on physical examination, clinical signs, and S _rel detected by ultrasonographic findings. The individual prostatic volume (IPV) was divided by the expected prostatic volume (EPV) to determine the relative prostatic size in dogs over 4 years old. Platelet indices were compared between the two groups, and a correlation between S _rel and these indices was calculated.

Results

The median S _rel of dogs in group A was significantly higher (P = 0.001), and the mean plateletcrit (PCT) was significantly lower (P = 0.003) compared with those in group B. S _rel showed a significant negative correlation with PLT and PCT (r = -0.388; P = 0.02 and r = -0.402; P = 0.01). Receiver operating characteristic (ROC) analysis showed PLT and PCT thresholds for estimating S _rel > 1 with 75% and 87.5% sensitivity and 71.82 and 63.64% specificity.

Discussion

The findings of this study support the use of platelet indices like PLT and PCT to detect clinical BPH in dogs. However, more research is needed to confirm their utility in conjunction with other previously described diagnostic factors.

Mean Platelet Volume and Platelet Volume Distribution Width in Canine Parvoviral Enteritis

Bacterial translocation from the damaged intestinal tract, reported in canine parvoviral (CPV) enteritis, is thought to be responsible for the systemic inflammatory response resulting from coliform septicemia, which could ultimately progress to septic shock and death. Alterations in platelet indices, specifically mean platelet volume (MPV), is a consistent finding in critically ill people and dogs with and without sepsis. Increased MPV has been reported to be an indirect indicator of platelet activation and of bone marrow response in people and dogs with sepsis. The study aim was to compare admission MPV and platelet volume distribution width (PVDW) in dogs with CPV enteritis to that of healthy aged-matched control dogs. Forty-eight dogs with CPV enteritis and 18 healthy age matched control dogs were included. CPV infection was confirmed with electron microscopy and concurrent blood-borne infections were excluded using PCR. EDTA whole blood samples were analyzed on an automated cell counter, ADVIA 2120, within 30-60 min from collection. There was no significant difference for platelet count between the groups. The MPV for CPV infected dogs (median: 14.0; IQR: 12.2–15.1) was significantly higher compared to controls (11.3; IQR: 10.3–13.1, P = 0.002). The PVDW for CPV infected dogs (66.9; IQR: 64.2–68.8) was significantly higher compared to controls (63.3; IQR: 60.2–65.1, P < 0.001). These findings suggest that significant platelet activation is present in dogs with CPV enteritis which may play a role in the disease outcome, similar to people with sepsis. Further studies are required to investigate the prognosticating ability of MPV in dogs with CPV enteritis.

Common Thrombotic Disorders Defined by CBC Platelet Parameters

The Coulter STKS mean platelet volume (MPV), platelet distribution width (PDW), mean corpuscular volume (MCV), and hematocrit (HCT) are assessed in thrombotic diseases. Complete blood counts (CBCs) were studied retrospectively in 645 consecutive hospital cases and, 850 "CBCs with blood films to the pathologist." Because the MPV and PDW are time dependant, nomograms and tables were created for the 0-25- and 26-40-min elapsed time intervals. In this study, abnormal CBC platelet parameters were found in the majority of patients with common thrombotic diseases, such as diabetes, atherosclerosis, hypertension, congestive heart failure, deep vein thrombosis (DVT), and toxemia. Thrombotic disease-related CBC categories include combined elevated MPV and PDW, elevated MPV or PDW alone, "MCV/MPV mismatch" (failure of physiologic "MCV/MPV match"), rheologic problem of elevated HCT and MPV, and mild thrombocytopenia with decreased MPV and high PDW. Anticoagulants and steroids often decrease the MPV. CBC platelet parameter abnormalities provide a new useful classification of thrombotic diseases in daily practice.

Platelet indices are novel predictors of hospital mortality in intensive care unit patients

BACKGROUND AND OBJECTIVE

Platelet volume indices (PVIs) are inexpensive and readily available in intensive care units (ICUs). However, their association with mortality has never been investigated in a critical care setting. Our study aimed to investigate the association of PVI and mortality in unselected ICU patients.

METHODS

This was a retrospective study conducted in a mixed 24-bed ICU from September 2010 to December 2012. Platelet indices including mean platelet volume (MPV), platelet distribution width (PDW), platelet count, and plateletcrit were measured on ICU entry. Univariable analyses were performed to screen for variables that were associated with mortality. Variables with P < .1 were incorporated into a regression model to adjust for the odds ratio of platelet indices.

RESULTS

A total of 1556 patients were included during the study period, including 1113 survivors and 443 nonsurvivors (mortality rate: 28.47%). Platelet distribution width and MPV were significantly higher in nonsurvivors than in survivors. Platelet distribution width greater than 17% and MPV greater than 11.3 fL were independent risk factors for mortality (adjusted odds ratio: 1.92 and 1.84, respectively) and survival time (hazards ratio: 1.77 and 1.75, respectively).

CONCLUSION

Higher MPV and PDW are associated with increased risk of death, whereas the decrease in plateletcrit is associated with increased mortality risk.

Static platelet adhesion, flow cytometry and serum TXB2 levels for monitoring platelet inhibiting treatment with ASA and clopidogrel in coronary artery disease: a randomised cross-over study

Background

Despite the use of anti-platelet agents such as acetylsalicylic acid (ASA) and clopidogrel in coronary heart disease, some patients continue to suffer from atherothrombosis. This has stimulated development of platelet function assays to monitor treatment effects. However, it is still not recommended to change treatment based on results from platelet function assays. This study aimed to evaluate the capacity of a static platelet adhesion assay to detect platelet inhibiting effects of ASA and clopidogrel. The adhesion assay measures several aspects of platelet adhesion simultaneously, which increases the probability of finding conditions sensitive for anti-platelet treatment.

Methods

With a randomised cross-over design we evaluated the anti-platelet effects of ASA combined with clopidogrel as well as monotherapy with either drug alone in 29 patients with a recent acute coronary syndrome. Also, 29 matched healthy controls were included to evaluate intra-individual variability over time. Platelet function was measured by flow cytometry, serum thromboxane B₂ (TXB₂)-levels and by static platelet adhesion to different protein surfaces. The results were subjected to Principal Component Analysis followed by ANOVA, t-tests and linear regression analysis.

Results

The majority of platelet adhesion measures were reproducible in controls over time denoting that the assay can monitor platelet activity. Adenosine 5'-diphosphate (ADP)-induced platelet adhesion decreased significantly upon treatment with clopidogrel compared to ASA. Flow cytometric measurements showed the same pattern (r² = 0.49). In opposite, TXB₂-levels decreased with ASA compared to clopidogrel. Serum TXB₂ and ADP-induced platelet activation could both be regarded as direct measures of the pharmacodynamic effects of ASA and clopidogrel respectively. Indirect pharmacodynamic measures such as adhesion to albumin induced by various soluble activators as well as SFLLRN-induced activation measured by flow cytometry were lower for clopidogrel compared to ASA. Furthermore, adhesion to collagen was lower for ASA and clopidogrel combined compared with either drug alone.

Conclusion

The indirect pharmacodynamic measures of the effects of ASA and clopidogrel might be used together with ADP-induced activation and serum TXB₂ for evaluation of anti-platelet treatment. This should be further evaluated in future clinical studies where screening opportunities with the adhesion assay will be optimised towards increased sensitivity to anti-platelet treatment.

[Hemocompatibility of various synthetic granulates]

The adherence of platelets to different polymer granulates was examined in a perfusion chamber filled with platelet-rich plasma. The surface area of each of the granulates was of a standardised size. The results were compared with those found for a non-thrombogenic and a highly thrombogenic foreign-body surface. The three polymers examined-Cryolite, Styrolux and Zylar-must be considered non-thrombogenic. Platelet adherence to these substances is significantly less (3%) than that to a highly thrombogenic surface such as glass (95%). The three materials did not differ in terms of platelet adherence, and would appear to be suitable potential materials for use in cell separators.

Surgical stress induces a shift in the type-1/type-2 T-helper cell balance, suggesting down-regulation of cell-mediated and up-regulation of antibody-mediated immunity commensurate to the trauma

BACKGROUND

Measuring serum cytokines, pituitary hormones, or acute phase proteins during or after surgery is not an optimal method for quantifying the impact of surgical procedures. In an effort to assess surgical stress by means of the immune response, we focused on changes in cell-mediated and antibody-mediated immunity as illustrated by the type 1/type 2 T-helper (Th1/Th2) cell balance. The sensitivity of this approach was evaluated by comparing laparoscopic and conventional cholecystectomy (LCE, CCE).

METHODS

In a pragmatic prospective study 43 patients with symptomatic cholelithiasis were operated on either by LCE (n = 25) or CCe (n = 18). Blood sampling was done 24 hours before surgery, immediately before incision, and 2, 24, and 48 hours after surgery. Cell surface markers and cytokine production were used to characterize the Th1/Th2 balance and were measured by means of flow cytometry and enzyme-linked immunosorbent assay techniques.

RESULTS

Activation of Th2 cells evokes the production and secretion of interleukin-4 (IL-4), which up-regulates the expression of immunoglobulin E receptors (Fo epsilon RII, CD23) on B cells. Phytohemagglutinin-induced IL-4 production in freshly isolated peripheral blood mononuclear cells from patients increased more after CCE than LCE (IL-4, +41% versus +17%; p < 0.05). Also the expression of CD23 on B cells was higher after CCE than LCE (+146% versus +63%; P < 0.01). CD30, a membrane molecule that belongs to the tumor necrosis factor receptor superfamily and probably is an important indicator of Th2 activity, was more evaluated on T cells from patients who underwent CCE. The Th1 response, characterized by phytohemagglutinin-induced IFN-gamma secretion in peripheral blood mononuclear cells and up-regulation of human leukocyte antigen-DR expression on monocytes, was lower after CCE than after LCE.

CONCLUSIONS

This study shows that surgical stress induces a shift in the Th1/Th2 balance toward Th2, suggesting that cell-mediated immunity is down-regulated and antibody-mediated immunity is up-regulated after surgery. The evaluation of this shift may be clinically meaningful and help quantify even less invasive surgical procedures. When comparing CCE and LCE in this not strictly randomized study, we found LCE to be the less stressful procedure.

Platelet function defects associated with hemorrhage or thrombosis

Platelet dysfunction, especially acquired forms, is a common cause of hemorrhage, especially when associated with trauma or surgery. Although the hereditary platelet function defects are generally quite rare, hereditary storage pool disease is common enough to be suspected in an individual, usually a child, with characteristic historical and clinical findings. The acquired platelet function defects, especially those resulting from drugs, are common and should promptly be suspected in patients developing easy and spontaneous bruising, mild-to-moderate mucosal membrane hemorrhage, or unexplained bleeding associated with trauma or surgery. The template bleeding time is generally useful as a screening test of platelet function, but a normal template bleeding time, in the face of a suggestive history, suggestive clinical findings, or in a patient frankly bleeding, is not reliable, and platelet aggregation or lumiaggregation should be done in appropriate clinical situations. Also, prolongation of the template bleeding time is an unreliable predictor of clinical bleeding propensity. The mainstay of therapy for almost all these defects, if bleeding is significant, is the liberal infusion of appropriate numbers of platelet concentrates. The acquired platelet function defects should also be managed by attempts to treat or control the underlying disease, if possible, and offending drugs or potentially offending drugs should immediately be stopped.

Masking of heparin activity in the activated coagulation time (ACT) by platelet procoagulant activity

The effect of platelet procoagulant activity in the Activated Coagulation Time (ACT) was measured in whole blood anticoagulated with various levels of heparin before or after reversal with protamine. Similar studies were carried out on blood anticoagulated with hirudin to distinguish procoagulant activity from heparin neutralization in platelet preparations. At 0.5-1.0 units/mL antithrombin activity with heparin or hirudin, the ACT was lowered progressively by the addition of increasing concentrations of lysed platelets to as much as 20 seconds below the baseline clotting time obtained with unanticoagulated blood samples. Neutralization of higher concentrations of heparin with protamine produced an ACT below baseline in the presence of lysed platelets. Aprotinin (400 KIU/mL) prolonged the ACT slightly in heparinized whole blood, but did not prevent the lowering of the ACT by lysed platelets to baseline or below. Recirculation of heparinized whole blood in a simulated cardiopulmonary bypass circuit generated platelet microparticles detected by flow cytometry. An increase in platelet microparticles was associated with a decrease in the amount of protamine needed to reach the baseline ACT in blood samples removed from the circuit at various time points during recirculation. A chromogenic anti-Factor Xa assay of heparin did not show a change with increasing microparticle concentration during recirculation. These findings indicate a masking of heparin activity by the procoagulant activity of platelet membrane microparticles that could affect reversal of heparin based on the ACT.