Prophylactic Platelet Transfusion: Is There Evidence of Benefit, Harm, or No Effect?

The optimal use of prophylactic platelet transfusion remains uncertain in a number of clinical scenarios. Platelet count thresholds have been established in patients with hematologic malignancies, yet thresholds backed by scientific data are limited or do not exist for many patient populations. Clinical scenarios involving transfusion thresholds for thrombocytopenic patients with critical illness, need for surgery or invasive procedures, or those involving specials populations like children and neonates, lack clear evidence for discerning favorable outcomes without undue risk related to platelet transfusion. In addition, while prophylactic platelet transfusions are administered with the goal of enhancing hemostasis, increasing evidence supports critical nonhemostatic roles for platelets related to innate and adaptive immunity, inflammation, and angiogenesis, which may impact patient responses and outcomes. Here we review several recent studies conducted in adult or pediatric patients that highlight the limitations in our current understanding of prophylactic platelet transfusion. Together, these studies underscore the need for additional research, especially in the form of robust randomized clinical trials and integrating additional parameters beyond the platelet count. Future research at the basic, translational, and clinical levels will best define the optimal role for prophylactic transfusion across the lifespan and its broader impact on health and disease.

Preoperative Type and Screen Before General Thoracic Surgery: A Nomogram to Reduce Unnecessary Tests

BACKGROUND

A preoperative type and screen (T&S) is traditionally routinely obtained before noncardiac thoracic surgery; however an intraoperative blood transfusion is rare. This practice is overly cautious and expensive.

METHODS

We included adult patients undergoing major thoracic surgery at the Mayo Clinic from 2007 to 2016. Patients receiving a T&S blood test ≤72 hours of surgery was the main exposure. We randomly split the cohort into derivation and validation datasets. We used multiple logistic regression to create a parsimonious nomogram predicting the need for a T&S in relation to the likelihood of intraoperative blood transfusion. We validated the nomogram in terms of discrimination, calibration, and negative predictive value.

RESULTS

Of 6280 patients 46.1% had a preoperative T&S, but only 7.1% received intraoperative transfusions. The derivation dataset had 4196 patients. Patients who had a T&S were more likely to have baseline hemoglobin level <10 g/dL (7.9% vs 3.6%, P < .001) and less likely to have minimally invasive operations (36.1% vs 43.5%, P < .001) but were otherwise similar in baseline age and comorbidities. A transfusion threshold of 5% was selected a priori. The nomogram included age, planned operation, approach, body mass index, and preoperative hemoglobin. The nomogram was validated with a c-statistic of 86% and a negative predictive value of 97.9%. Patients who needed a blood transfusion but who did not have a preoperative T&S did not have a higher rate of mortality (P = .121).

CONCLUSIONS

An intraoperative blood transfusion during major thoracic surgery is a rare event. Patient who required transfusion but did not have a T&S did not have worse outcomes. A simple nomogram can aid in the selective use of T&S orders preoperatively.

Equivalent inpatient mortality among direct-acting oral anticoagulant and warfarin users presenting with major hemorrhage

BACKGROUND

Extrapolation of clinical trial results comparing warfarin and direct-acting oral anticoagulant (DOAC) users experiencing major hemorrhage to clinical care is challenging due to differences seen among non-randomized oral anticoagulant users, bleed location, and etiology. We hypothesized that inpatient all-cause-mortality among patients presenting with major hemorrhage differed based on the home-administered anticoagulant medication class, DOAC versus warfarin.

METHODS

More than 1.5 million hospitalizations were screened and 3731 patients with major hemorrhage were identified in the REDS-III Recipient Database. Propensity score matching and stratification were used to account for potentially confounding factors.

RESULTS

Inpatient all-cause-mortality was lower for DOAC (HR = 0.60, 95%CI 0.45-0.80, p = 0.0005) before accounting for confounding and competing events. Inpatient all-cause-mortality for 1266 propensity-score-matched patients compared using proportional hazards regression did not differ (HR = 0.84, 95%CI 0.58-1.22, p = 0.36). Inpatient all-cause-mortality in stratified analyses (warfarin as reference) produced: HR = 0.69 (95%CI 0.31-1.55) for traumatic head injuries; HR = 1.10 (95%CI 0.62-1.95) for non-traumatic head injuries; HR = 0.62 (95%CI 0.20-1.94) for traumatic, non-head injuries; and HR = 0.69 (95%CI 0.29-1.63) for non-traumatic, non-head injuries. Mean time to discharge was shorter for DOAC (HR = 1.17, 95%CI 1.05-1.30, p = 0.0034) in the propensity score matched analysis. Plasma transfusion occurred in 42% of warfarin hospitalizations and 11% of DOAC hospitalizations. Vitamin K was administered in 63% of warfarin hospitalizations.

CONCLUSIONS

After accounting for differences in patient characteristics, location of bleed, and traumatic injury, inpatient survival was no different in patients presenting with major hemorrhage while on DOAC or warfarin.

Predicting Prolonged Stay in the ICU Attributable to Bleeding in Patients Offered Plasma Transfusion

In blood transfusion studies, plasma transfusion (PPT) and bleeding are known to be associated with risk of prolonged ICU length of stay (ICU-LOS). However, as patients can show significant heterogeneity in response to a treatment, there might exists subgroups with differential effects. The existence and characteristics of these subpopulations in blood transfusion has not been well-studied. Further, the impact of bleeding in patients offered PPT on prolonged ICU-LOS is not known. This study presents a causal and predictive framework to examine these problems. The two-step approach first estimates the effect of bleeding in PPT patients on prolonged ICU-LOS and then estimates risks of bleeding and prolonged ICU-LOS. The framework integrates a classification model for risks prediction and a regression model to predict actual LOS. Results showed that the effect of bleeding in PPT patients significantly increases risk of prolonged ICU-LOS (55%, p=0.00) while no bleeding significantly reduces ICU-LOS (4%, p=0.046).

Effects of Plasma Transfusion on Perioperative Bleeding Complications: A Machine Learning Approach

Perioperative bleeding (PB) is associated with increased patient morbidity and mortality, and results in substantial health care resource utilization. To assess bleeding risk, a routine practice in most centers is to use indicators such as elevated values of the International Normalized Ratio (INR). For patients with elevated INR, the routine therapy option is plasma transfusion. However, the predictive accuracy of INR and the value of plasma transfusion still remains unclear. Accurate methods are therefore needed to identify early the patients with increased risk of bleeding. The goal of this work is to apply advanced machine learning methods to study the relationship between preoperative plasma transfusion (PPT) and PB in patients with elevated INR undergoing noncardiac surgery. The problem is cast under the framework of causal inference where robust meaningful measures to quantify the effect of PPT on PB are estimated. Results show that both machine learning and standard statistical methods generally agree that PPT negatively impacts PB and other important patient outcomes. However, machine learning methods show significant results, and machine learning boosting methods are found to make less errors in predicting PB.

A multicenter study of plasma use in the United States

BACKGROUND

Detailed information regarding plasma use in the United States is needed to identify opportunities for practice improvement and design of clinical trials of plasma therapy.

STUDY DESIGN AND METHODS

Ten US hospitals collected detailed medical information from the electronic health records for 1 year (2010-2011) for all adult patients transfused with plasma.

RESULTS

A total of 72,167 units of plasma were transfused in 19,596 doses to 9269 patients. The median dose of plasma was 2 units (interquartile range, 2-4; range 1-72); 15% of doses were 1 unit, and 45% were 2 units. When adjusted by patient body weight (kg), the median dose was 7.3 mL/kg (interquartile range, 5.5-12.0). The median pretransfusion international normalized ratio (INR) was 1.9 (25%-75% interquartile range, 1.6-2.6). A total of 22.5% of plasma transfusions were given to patients with an INR of less than 1.6 and 48.5% for an INR of 2.0 or more. The median posttransfusion INR was 1.6 (interquartile range, 1.4-2.0). Only 42% of plasma transfusions resulted in a posttransfusion INR of less than 1.6. Correction of INR increased as the plasma dose increased from 1 to 4 units (p < 0.001). There was no difference in the INR response to different types of plasma. The most common issue locations were general ward (38%) and intensive care unit (ICU; 42%).

CONCLUSION

This large database describing plasma utilization in the United States provides evidence for both inadequate dosing and unnecessary transfusion. Measures to improve plasma transfusion practice and clinical trials should be directed at patients on medical and surgical wards and in the ICU where plasma is most commonly used.

Use of an inspiratory impedance threshold valve during cardiopulmonary resuscitation: a progress report

Building upon studies on the mechanism of active compression-decompression (ACD) cardiopulmonary resuscitation, a new inspiratory impedance threshold valve has been developed to enhance the return of blood to the thorax during the decompression phase of CPR. Use of this device results in a greater negative intrathoracic pressure during chest wall decompression. This leads to improved vital organ perfusion during both standard and ACD CPR. Animal and human studies suggest that this simple device increases cardiopulmonary circulation by harnessing more efficiently the kinetic energy of the outward movement of the chest wall during standard CPR or active chest wall decompression. When used in conjunction with ACD CPR during clinical evaluation, addition of the impedance valve resulted in sustained systolic pressures of greater than 100 mmHg and diastolic pressures of greater than 55 mmHg. The new valve may be beneficial in patients in asystole or shock refractory ventricular fibrillation, when enhanced return of blood flow to the chest is needed to 'prime the pump'. The potential long-term benefits of this new valve remain under investigation.