Viscoelastic haemostatic point-of-care assays in the management of postpartum haemorrhage: a narrative review.

Viscoelastic haemostatic assays provide rapid testing at the bed-side that identify all phases of haemostasis, from initial fibrin formation to clot lysis. In obstetric patients, altered haemostasis is common as pregnancy is associated with coagulation changes that may contribute to bleeding events such as postpartum haemorrhage, as well as thrombosis events. In this narrative review, we examine the potential clinical utility of viscoelastic haemostatic assays in postpartum haemorrhage and consider the current recommendations for their use in obstetric patients. We discuss the clinical benefits associated with the use of viscoelastic haemostatic assays due to the provision of (near) real-time readouts with a short turnaround, coupled with the identification of coagulation defects such as hypofibrinogenaemia. The use of viscoelastic haemostatic assay-guided algorithms may be beneficial to diagnose coagulopathy, predict postpartum haemorrhage, reduce transfusion requirements and monitor fibrinolysis in women with obstetric haemorrhage. Further studies are required to assess whether viscoelastic haemostatic assay-guided treatment improves clinical outcomes, and to confirm the utility of prepartum viscoelastic haemostatic assay measurements for identifying patients at risk of postpartum haemorrhage.

When and how should I transfuse during obstetric hemorrhage?

The incidence of maternal hemorrhage and blood transfusion has increased over time. Causes of massive hemorrhage, defined as a transfusion > 10 units of erythrocytes, include abnormal placental insertion, preeclampsia, and placental abruption. Although ratio-based transfusion has been described for managing massive hemorrhage, a goal-directed approach using laboratory or point-of-care data may lead to better outcomes. Autotransfusion, which involves the collection, washing, and filtration of maternal shed blood, avoids many of the complications associated with allogeneic blood transfusion. In this review, we provide an overview of transfusion practices related to the management of obstetric hemorrhage.

Adult extracorporeal membrane oxygenation: an international survey of transfusion and anticoagulation techniques.

BACKGROUND AND OBJECTIVES: Extracorporeal membrane oxygenation (ECMO) is a method of life support for either isolated cardiac failure or respiratory failure, with or without cardiac failure. When used for hemodynamic support, the ECMO circuit presents a non-endothelialized, artificial surface to blood inciting an inflammatory response which activates haemostatic pathways. Anticoagulation may complicate a pre-existing coagulopathy and/or inadequate surgical hemostasis of varying severity. There is no standardized method to achieve and monitor anticoagulation or guide transfusion therapy during ECMO. We tested the hypothesis that institutions across the world conduct similar management of anticoagulation and transfusion during adult ECMO support. METHODS: This is a descriptive, self-reporting cross-sectional survey of anticoagulation and transfusion practice for patients age 18 or older on ECMO. This 38 multiple-choice question survey was sent to 166 institutions, internationally, utilizing adult ECMO. About 32·4% (54) of institutions responded. Responses were anonymously collected. Descriptive analyses were calculated. RESULTS: Our findings indicate there appears to be a significant practice variation among institutions regarding anticoagulation and transfusion during adult ECMO support. DISCUSSION: The lack of standard practices among institutions may reflect a paucity of data regarding optimal anticoagulation and transfusion for patients requiring ECMO. Standardized protocols for anticoagulation and transfusion may help increase quality of care for and reduce morbidity, mortality and cost to patients and healthcare centres. Further study is required for standardized, high quality care.

The effects of a data driven maximum surgical blood ordering schedule on preoperative blood ordering practices.

OBJECTIVES: The maximum surgical blood ordering schedule (MSBOS) provides guidelines for pre-operative pre-transfusion testing for elective surgical procedures. This study compared blood ordering and utilization during the period when the MSBOS was created by achieving consensus between the blood bank and the various surgical specialties, and after the introduction of an MSBOS created by using department-specific red blood cell (RBC) transfusion data (data driven MSBOS, dMSBOS). METHODS: The dMSBOS was created by analyzing 12 months of RBC transfusion data for each procedure across a regional health system. Pre-transfusion testing and the RBC crossmatch:transfusion (C:T) ratios at 8 of the hospitals were compared between the 12 month period before the dMSBOS was introduced, and the 15 months after its introduction. RESULTS: There were significant reductions in the median monthly number of type and screens not associated with RBC crossmatches (10 714-10 061; p < 0.0001) and the median number of type and screens associated with RBC crossmatches (10 127-9 349; p = 0.0014) on surgical patients after dMSBOS implementation. There were significant decreases in the median number of monthly RBC units crossmatched (2 981-2 444; p < 0.0001) and transfused (890-791; p < 0.0001) to surgical patients after implementing the dMSBOS. The overall system-wide C:T ratio trended down after dMSBOS implementation (from 3.34 to 3.17, p = 0.067). DISCUSSION: Crossmatching fewer RBC units facilitates more efficient management of the blood bank's inventory. CONCLUSION: The dMSBOS was effective in reducing the extent of unnecessary pre-transfusion testing before surgery and reduced the number of RBCs that were crossmatched for specific patients.

Excessive quantities of red blood cells are issued to the operating room.

OBJECTIVES: To determine what percentage of red blood cell (RBC) units that were issued to the operating room (OR) were returned unused, and to determine how often all of the RBCs that were issued for a patient were returned unused using the institution's maximum surgical blood ordering schedule (MSBOS) as a guide. BACKGROUND: The MSBOS provides guidelines for blood ordering, but is merely a suggestion for the ordering clinicians. This study examined how closely ordering practices followed the MSBOS, and how often ordered RBCs were actually transfused. METHODS: For a 4-week period, RBC issue and utilization data were collected on elective surgery patients who were eligible for electronic cross-match at a tertiary care hospital. These data were compared to the MSBOS. RESULTS: There were 1350 surgical procedures performed. Of these cases, 439 patients had a type and screen (T&S) performed, and 215/439 (49%) patients had at least 1 RBC issued during their case. To these 215 patients, 742 RBC units were issued and 537/742 (72%) of these units were returned to the blood bank unused. In 152/215 (71%) cases with issued RBCs, all of the RBCs were returned to the blood bank unused. Amongst the surgical categories in this study, the percentage of cases where none of the issued RBCs were transfused ranged from 38 to 93%. CONCLUSIONS: Significant numbers of RBC units are issued but not transfused during surgery. Involving the surgical team in the blood issuing process and using a data-driven MSBOS may reduce the number of unused units.

Role of the massive transfusion protocol in the management of haemorrhagic shock.

The concept of rapid delivery of multiple blood products to the bedside of a massively haemorrhaging patient seems to be a logical approach to the management of the massively bleeding patient. However, controversy exists in the use of fixed blood component ratios. Assessing the extent of the coagulopathy through point-of-care testing might provide patients with product administration as needed, and avoid excessive transfusion and its associated complications.

Impulsivity, cognitive function, and their relationship in heroin-dependent individuals.

There is mixed evidence concerning cognitive function and heroin dependence. In this study, abstinent heroin-dependent individuals (n = 86) and age- and sex-matched non-drug-using controls (n = 88) were compared on self-report measures of impulsivity and computerized assessments of cognitive function. Abstinent heroin-dependent individuals reported greater motor impulsivity and experience seeking and showed functional weaknesses in cognitive ability, including impulsivity and distractibility (d = 0.28 to 0.49), but not decision making or working memory. Self-reported impulsivity was uncorrelated with cognitive function. These results suggest underlying brain-related factors in heroin dependence and have implications for therapeutic intervention.

Haemolysis and sublethal injury of RBCs after routine blood bank manipulations.

OBJECTIVES: To determine the extent of RBC sublethal injury in male donor units as measured by both the mechanical fragility index (MFI) and percentage haemolysis after RBCs underwent leucoreduction (LR), irradiation (IRRAD), and washing. BACKGROUND: RBCs frequently undergo post-collection processing to meet certain recipient's special needs. The extent of haemolysis and sublethal injury following these interventions has not been fully characterised. METHODS: Eight to ten day old male, AS-5 RBCs underwent either LR, IRRAD or washing. A control group of male, AS-5 RBCs were unmanipulated. The MFI, percent haemolysis, and plasma free haemoglobin (PFHb) were measured immediately after manipulation and, for a series of irradiated RBCs, 28 days after irradiation (IRRAD28). RESULTS: The MFI of the washed units was significantly higher than unmanipulated, LR, IRRAD, IRRAD28 units (P < 0·0001). The percent haemolysis was highest in the IRRAD28 units (1·4%) followed by the washed units (0·74%); the other three units demonstrated significantly less haemolysis (P < 0·0001). The largest mean total amount of PFHb per unit was found in the IRRAD28 units (500·5 mg/unit) followed by the washed units (149·8 mg/unit); the mean total amount of PFHb in the three other types of units was significantly less than that found in both the IRRAD28 and washed units (P at least < 0·001). CONCLUSION: There is a significant quantity of PFHb in IRRAD28 RBC units, and potentially in washed allogeneic RBC units. Clinical correlation is required to determine if this quantity of PFHb and the transfusion of potentially fragile RBCs causes adverse events.

Menopausal status affects the susceptibility of stored RBCs to mechanical stress.

The mechanical fragility index (MFI) is an in vitro measure of sublethal injury to RBCs. In our previous experiments, we demonstrated that an increase in sublethal injury (increasing MFI) was a component of the RBC storage lesion, and that the MFI was significantly higher amongst the RBC units from male donors compared to pre-menopausal female donors during storage. It was hypothesized that hormonal or menstrual factors contributed to this difference. In this study, we found that RBC units donated by post-menopausal women demonstrated an MFI that was significantly higher than those donated by pre-menopausal women throughout storage.

The use of thromboelastography for the peripartum management of a patient with platelet storage pool disorder.

We describe the peripartum management of a 26-year-old primigravida with a platelet storage pool disorder who underwent spontaneous vaginal delivery of twins with epidural analgesia. Postpartum hemorrhage from uterine atony, and cervical and vaginal lacerations were treated successfully with 1-desamino-8D-arginine vasopressin and blood products. The use of thromboelastography in the assessment and management of bleeding risk in the setting of platelet storage pool disorder is described.

The use of the mechanical fragility test in evaluating sublethal RBC injury during storage.

BACKGROUND: The mechanical fragility index (MFI) is an in vitro measurement of the extent of RBC sublethal injury. Sublethal injury might constitute a component of the RBC storage lesion, thus the MFI was determined serially during routine RBC storage. METHODS: Leucoreduced AS-5- and SAGM-preserved RBCs were stored under routine blood bank conditions. The mechanical fragility (MF) of each unit was serially measured during storage. RESULTS: For both AS-5 and SAGM units, male and female RBCs demonstrated statistically significant increases in the MFI during storage. The MFI was significantly lower in AS-5 units compared to SAGM units throughout storage. Female RBCs had significantly lower MFI vs. male RBCs in both AS-5 and SAGM units at all times. No significant differences in MFI were observed between ABO groups for both genders for AS-5 RBCs. CONCLUSIONS: The MF of RBCs increases during storage. Both gender and preservation solution influenced the MFI; however, the male:female MFI ratios were similar at all time-points and remained stable, suggesting that gender-based biological differences exist independent of storage solution. The MF could be a useful test for evaluating the effect of novel interventions intended to mitigate the susceptibility of RBCs to sublethal injury during storage.

I.V. infusion of a drag-reducing polymer extracted from aloe vera prolonged survival time in a rat model of acute myocardial ischaemia.

BACKGROUND: I.V. infusion of drag-reducing polymers (DRPs) has been shown to improve survival time in animals subjected to haemorrhagic shock. We hypothesized that DRPs might prolong survival time in rats following acute myocardial ischaemia (AMI). METHODS: Sixteen adult male rats were anaesthetized and mechanically ventilated. An i.v. infusion of either Dextran-40 2.5% (Control, n=8) or Dextran-40 2.5% containing 50 microg ml(-1) of an aloe vera-based DRP (DRP, n=8) was initiated at 3.5 ml h(-1). The left anterior descending coronary artery was ligated. Blood pressure, skin-tissue perfusion, and heart rate were monitored and arterial blood samples were analysed. RESULTS: The mortality at 60 min following coronary ligation was 0% in the DRP group vs 50% in the control group (P=0.025). DRP-treated animals maintained higher mean arterial pressure [60.9 (5.1) vs 47.5 (5.1) mm Hg, P=0.004] and tissue perfusion [4.2 (3.4) vs 1.2 (0.5) TPU, P=0.029]. The DRP group trended towards better acid-base status with base excess [-5.0 (1.7) vs -8.1 (5.1) mmol litre(-1), P=0.083] and pH [7.42 (0.07) vs 7.35 (0.02), P=0.03]. CONCLUSIONS: Administration of nanomolar concentrations of aloe vera-based DRP prolonged survival time in animals with AMI. DRPs may offer a novel method to treat organ/tissue hypoperfusion.

Anesthetic management for emergency cesarean section in a patient with severe valvular disease and preeclampsia.

Wider selection of young patients for prosthetic valve replacement for valvular heart disease has resulted in an increase in number of women with heart disease reaching childbearing age. Such patients presenting in labor for emergency cesarean section require special consideration. We present a report of a parturient who presented at 36 weeks of gestation with severe aortic and mitral stenosis, pulmonary edema and severe preeclampsia. The goals of our anesthetic management included (1) careful airway management (2) maintaining stable hemodynamics (3) optimizing fluid status, and (4) preventing seizures. Issues related to management of patients with severe valvular disease, prosthetic valves and complications due to anticoagulant therapy during pregnancy are discussed.

A comparison of three facemasks used during the induction of general anaesthesia.

BACKGROUND AND OBJECTIVE: A prospective crossover randomized trial was conducted to compare the performance of three commonly used anaesthetic facemasks: a clear plastic 'Anaesthetic Facemask' with pre-inflated air cushion, no inflation valve, and for single use (Intersurgical Limited, Wokingham, UK), a clear plastic 'Air Cushion Mask' with inflatable air cushion and inflation valve, and for single use (Proact Medical Limited, Kettering, UK), and a black antistatic reusable rubber facemask with pre-inflated air cushion, and no inflation valve (Datex Ohmeda Limited, Hatfield, UK). METHODS: After local Ethics Committee approval, written consent was taken from 60 ASA 1 or 2 patients undergoing elective ENT procedures. Following routine intravenous anaesthetic induction and muscle relaxation, a Guedel's oropharyngeal airway was inserted and each of the facemasks tried in a crossover fashion. The degree of chest expansion, the feel on the reservoir bag, the degree of leak around the mask and the overall satisfaction of the anaesthetist were graded and recorded for each facemask. RESULTS: Both the plastic facemasks performed similarly in all the four criteria. The antistatic rubber facemask performed significantly better than the plastic facemasks in these criteria (P < 0.05). CONCLUSIONS: This study has shown that the antistatic rubber facemask outperformed the two plastic facemasks during routine induction of general anaesthesia. We hope this will encourage manufacturers to improve disposable facemask design to simulate the antistatic rubber facemask.

Errors during intraoperative cell salvage because of inappropriate wash solutions.

IMPLICATIONS: Two case reports illustrate errors that can occur during intraoperative red blood cell salvage and emphasize the need for standardized procedures and quality improvement processes for this intervention.

Normal saline versus lactated Ringer's solution for intraoperative fluid management in patients undergoing abdominal aortic aneurysm repair: an outcome study.

UNLABELLED: Metabolic acidosis and changes in serum osmolarity are consequences of 0.9% normal saline (NS) solution administration. We sought to determine if these physiologic changes influence patient outcome. Patients undergoing aortic reconstructive surgery were enrolled and were randomly assigned to receive lactated Ringer's (LR) solution (n = 33) or NS (n = 33) in a double-blinded fashion. Anesthetic and fluid management were standardized. Multiple measures of outcome were monitored. The NS patients developed a hyperchloremic acidosis and received more bicarbonate therapy (30 +/- 62 mL in the NS group versus 4 +/- 16 mL in the LR group; mean +/- SD), which was given if the base deficit was greater than -5 mEq/L. The NS patients also received a larger volume of platelet transfusion (478 +/- 302 mL in the NS group versus 223 +/- 24 mL in the LR group; mean +/- SD). When all blood products were summed, the NS group received significantly more blood products (P = 0.02). There were no differences in duration of mechanical ventilation, intensive care unit stay, hospital stay, and incidence of complications. When NS was used as the primary intraoperative solution, significantly more acidosis was seen on completion of surgery. This acidosis resulted in no apparent change in outcome but required larger amounts of bicarbonate to achieve predetermined measurements of base deficit and was associated with the use of larger amounts of blood products. These changes should be considered when choosing fluids for surgical procedures involving extensive blood loss and requiring extensive fluid administration. IMPLICATIONS: Predominant use of 0.9% saline solution in major surgery has little impact on outcome as assessed by duration of mechanical ventilation, intensive care unit stay, hospital stay, and postoperative complications, but it does appear to be associated with increased perioperative blood loss.

Bleeding in a patient receiving platelet aggregation inhibitors.

IMPLICATIONS: We describe a patient who experienced intraoperative bleeding after being treated with platelet receptor glycoprotein IIb/IIIa antagonist eptifibatide. We used Sonoclot and Thrombelastograph to monitor antiplatelet effects of eptifibatide.