Coagulation factor levels in neurosurgical patients with mild prolongation of prothrombin time: effect on plasma transfusion therapy

[Hemostatic disorders in neurosurgical patients: diagnostics and correction]

The authors analyzed the main causes of perioperative hemostatic disorders in neurosurgical patients. The problem of preoperative hemostatic screening, intraoperative and postoperative factors contributing to hemostatic disorders are considered. The authors also discuss the methods for correction of hemostatic disorders.

Preoperative evaluation of coagulation status in neuromodulation patients

OBJECTIVE

The incidence of hemorrhage in patients who undergo deep brain stimulation (DBS) and spinal cord stimulation (SCS) is between 0.5% and 2.5%. Coagulation status is one of the factors that can predispose patients to the development of these complications. As a routine part of preoperative assessment, the authors obtain prothrombin time (PT), partial thromboplastin time (PTT), and platelet count. However, insurers often cover only PT/PTT laboratory tests if the patient is receiving warfarin/heparin. The authors aimed to examine their experience with abnormal coagulation parameters in patients who underwent neuromodulation.

METHODS

Patients who underwent neuromodulation (SCS, DBS, or intrathecal pump implantation) over a 9-year period and had preoperative laboratory values available were included. The authors determined abnormal values on the basis of a clinical protocol utilized at their practice, which combined the normal ranges of the laboratory tests and clinical relevance. This protocol had cutoff values of 12 seconds and 39 seconds for PT and PTT, respectively, and < 120,000 platelets/μl. The authors identified risk factors for these abnormalities and described interventions.

RESULTS

Of the 1767 patients who met the inclusion criteria, 136 had abnormal preoperative laboratory values. Five of these 136 patients had values that were misclassified as abnormal because they were within the normal ranges at the outside facility where they were tested. Fifty-one patients had laboratory values outside the ranges of our protocol, but the surgeons reviewed and approved these patients without further intervention. Of the remaining 80 patients, 8 had known coagulopathies and 24 were receiving warfarin/heparin. The remaining 48 patients were receiving other anticoagulant/antiplatelet medications. These included apixaban/rivaroxaban/dabigatran anticoagulants (n = 22; mean ± SD PT 13.7 ± 2.5 seconds) and aspirin/clopidogrel/other antiplatelet medications (n = 26; mean ± SD PT 14.4 ± 5.8 seconds). Eight new coagulopathies were identified and further investigated with hematological analysis.

CONCLUSIONS

New anticoagulants and antiplatelet medications are not monitored with PT/PTT, but they affect coagulation status and laboratory values. Although platelet function tests aid in a subset of medications, it is more difficult to assess the coagulation status of patients receiving novel anticoagulants. PT/PTT may provide value preoperatively.

Spontaneous intracranial hemorrhage associated with dengue fever: An emerging concern for general physicians

Dengue fever (DF) is an arboviral disease caused by a positive-sense RNA virus of the genus Flavivirus. The overall incidence of DF has increased exponentially worldwide over the last three decades. The atypical clinical manifestations of DF grouped under expanded dengue syndrome (EDS), have also been reported more frequently for the last decade. These unusual manifestations are usually associated with coinfections, comorbidities, or complications of prolonged shock. Intracranial hemorrhage (ICH) is one of the rare manifestations of the central nervous system involvement by dengue as a part of EDS. The pathogenesis and treatment of this manifestation also remain controversial. Therefore, we report a case of a previously healthy 65-year-old female who developed ICH as a part of EDS along with a brief review of literature.

Clotting-Factor Concentrations 5 Days After Discontinuation of Warfarin

BACKGROUND

The American Society of Regional Anesthesia and Pain Medicine guidelines recommend discontinuation of warfarin and an international normalized ratio (INR) of 1.2 or less before a neuraxial injection. The European and Scandinavian guidelines accept an INR of 1.4 or less. We evaluated INR and levels of clotting factors (CFs) II, VII, IX, and X 5 days after discontinuation of warfarin.

METHODS

Patients who discontinued warfarin for 5 days and had an INR of 1.4 or less had activities of factors II, VII, IX, and X measured. The primary outcome was the frequency of subjects with CF activities of less than 40%.

RESULTS

Twenty-three patients were studied; 21 (91%) had an INR of 1.2 or less. In these 21 patients, the median (interquartile range) activities of factors II, VII, IX, and X were 66% (52%-80%), 114% (95%-132%), 101% (84%-121%), and 55% (46%-63%), respectively. Ninety-five percent (99% confidence interval, 69%-99%) had CF activities of greater than 40%. The patient who did not CF activities greater than 40% had end-stage renal disease. Two subjects had an INR of greater than 1.2; the activities of factor II, VII, IX, and X were 37% and 46%, 89% and 105%, 66% and 78%, and 20% and 36%, respectively. Neither patient had CF activities of greater than 40%.

CONCLUSIONS

Based on 40% activity of CFs, patients with INRs of 1.2 or less can be considered to have adequate CFs to undergo neuraxial injections. The number of patients with an INR of 1.3 and 1.4 is too small to make conclusions.

Blood Components Load in Post-operative Neurosurgical Patients Suspected with Disseminated Intravascular Coagulation

Neurosurgical patients with suspected DIC receive large amount of transfusion support in form of red cell concentrates (RCC), platelet rich plasma (PRP) and fresh frozen plasma (FFP). However, there are very few studies which have studied the effect of blood components load in the outcome of the patient. We conducted a prospective observational study on 61 post operative neurosurgery patients suspected with DIC and had at least one deranged haemostatic parameter namely platelet count, prothrombin time, partial thromboplastin time and thrombin time. Their blood components load was co-related with the outcome and with the hemostatic derangements. Twenty-eight patients died in our study group. 19/28 died patients had DIC. The red cell load was significantly more in patients who died compared to those who were alive (p = 0.041). On the other hand, load of PRP as well as FFP was significantly different between the patients who were alive and dead. This difference was further heightened when the DIC deaths were compared with the other patients. This is especially true for FFP transfusion which was significantly higher in DIC deaths (p = 0.006). Also, the number of FFPs received by neurosurgical patients suspected with DIC was significantly more in patients >2 coagulation abnormalities (p = 0.008). However, no correlation was found between PRP and RCC received and number of coagulation abnormalities present. To conclude, the load of FFP was maximum in patients with DIC deaths and the load of RCC was associated with overall mortality.

Appropriateness of Plasma Transfusion: A College of American Pathologists Q-Probes Study of Guidelines, Waste, and Serious Adverse Events

Context.—

Plasma transfusion guidelines support patient care and safety, management of product wastage, and compliance; yet, there is little information across multiple institutions about use of and adherence to plasma transfusion guidelines.

Objective.—

To survey multiple institutions regarding their plasma transfusion guidelines and compliance, plasma wastage rates, and incidence of transfusion reactions associated with plasma transfusion.

Design.—

The College of American Pathologists Q-Probes model was used to collect data from 89 participating institutions. Each site was asked to provide data relevant to its most recent 40 adult patient plasma transfusion episodes, and complete a questionnaire regarding plasma transfusion guidelines, utilization and wastage of plasma, and transfusion reactions related to plasma transfusion.

Results.—

The participating institutions reported a total of 3383 evaluable plasma transfusion episodes with transfusion of 9060 units of plasma. Compliance with institution-specific guidelines was seen in 3018 events (89%). Pretransfusion and posttransfusion coagulation testing was done in 3281 (97%) and 3043 (90%) of these episodes, respectively. Inappropriate criteria were noted for more than 100 transfusion episodes. Thirty-two plasma transfusion episodes (1%) were associated with a transfusion reaction. Serious and fatal reactions were reported. Median plasma wastage rate for the year preceding the study was 4.5%.

Conclusions.—

Most participating institutions are compliant with plasma transfusion guidelines based on published references, supported by appropriate testing. With transfusions for indications that lack evidence of efficacy and incidence of transfusion reactions, there is an ongoing role for transfusion service leaders to continue to update and monitor plasma transfusion practices.

Deadly intracranial bleed in patients with dengue fever: A series of nine patients and review of literature

INTRODUCTION

Dengue fever is a global pandemic threat with increasing incidence. To date, there are no cures and the effectiveness of dengue vaccines is still uncertain. World Heath Organization introduced expanded dengue syndrome to include unusual presentations of dengue fever including severe neurologic complications. One of the deadly complications is intracranial hemorrhage (ICH).

METHODOLOGY

We collected data of patients with ICH diagnosed via a plain computed tomography of the brain (CT brain) with thrombocytopenia and positive Dengue virus type 1 nonstructural protein (NS1) antigen test or positive dengue serology IgM from January 2014 till June 2015 at our center. Nine patients were included and all 20 other remaining patients reported in literature so far are discussed.

DISCUSSION

We found that all patients in our center requiring neurosurgical intervention died. Another interesting observation is that detection of Dengue IgG usually meant more severe ICH and poorer outcomes. From our series, platelet levels did not seem to influence the outcome.

CONCLUSION

We recommend that for early detection of ICH, Dengue IgG should be routinely screened and a high index of suspicion be maintained. Future research should be focused on determining predictors of ICH in patients with dengue fever so that preventive steps can be taken as mortality is high and no treatment seems beneficial at the moment once severe ICH occurs.

Intracranial pressure monitoring: fundamental considerations and rationale for monitoring

Traumatic brain injury (TBI) is a major cause of death and disability worldwide. In large part critical care for TBI is focused on the identification and management of secondary brain injury. This requires effective neuromonitoring that traditionally has centered on intracranial pressure (ICP). The purpose of this paper is to review the fundamental literature relative to the clinical application of ICP monitoring in TBI critical care and to provide recommendations on how the technique maybe applied to help patient management and enhance outcome. A PubMed search between 1980 and September 2013 identified 2,253 articles; 244 of which were reviewed in detail to prepare this report and the evidentiary tables. Several important concepts emerge from this review. ICP monitoring is safe and is best performed using a parenchymal monitor or ventricular catheter. While the indications for ICP monitoring are well established, there remains great variability in its use. Increased ICP, particularly the pattern of the increase and ICP refractory to treatment is associated with increased mortality. Class I evidence is lacking on how monitoring and management of ICP influences outcome. However, a large body of observational data suggests that ICP management has the potential to influence outcome, particularly when care is targeted and individualized and supplemented with data from other monitors including the clinical examination and imaging.

Successful implementation of a packed red blood cell and fresh frozen plasma transfusion protocol in the surgical intensive care unit

Background

Blood product transfusions are associated with increased morbidity and mortality. The purpose of this study was to determine if implementation of a restrictive protocol for packed red blood cell (PRBC) and fresh frozen plasma (FFP) transfusion safely reduces blood product utilization and costs in a surgical intensive care unit (SICU).

Study Design

We performed a retrospective, historical control analysis comparing before (PRE) and after (POST) implementation of a restrictive PRBC/FFP transfusion protocol for SICU patients. Univariate analysis was utilized to compare patient demographics and blood product transfusion totals between the PRE and POST cohorts. Multivariate logistic regression models were developed to determine if implementation of the restrictive transfusion protocol is an independent predictor of adverse outcomes after controlling for age, illness severity, and total blood products received.

Results

829 total patients were included in the analysis (PRE, n=372; POST, n=457). Despite higher mean age (56 vs. 52 years, p=0.01) and APACHE II scores (12.5 vs. 11.2, p=0.006), mean units transfused per patient were lower for both packed red blood cells (0.7 vs. 1.2, p=0.03) and fresh frozen plasma (0.3 vs. 1.2, p=0.007) in the POST compared to the PRE cohort, respectively. There was no difference in inpatient mortality between the PRE and POST cohorts (7.5% vs. 9.2%, p=0.39). There was a decreased risk of urinary tract infections (OR 0.47, 95%CI 0.28-0.80) in the POST cohort after controlling for age, illness severity and amount of blood products transfused.

Conclusions

Implementation of a restrictive transfusion protocol can effectively reduce blood product utilization in critically ill surgical patients with no increase in morbidity or mortality.

Transfusion of Blood and Blood Products

In transfusion medicine, several blood products can be prepared and used as replacement therapy; however, four of these products are more commonly used in general practice: RBCs, fresh frozen plasma (FFP), platelets and cryoprecipitate. RBC transfusions are mainly administered to improve tissue oxygenation in cases of anaemia or acute blood loss due to trauma or surgery. FFP, platelets and cryoprecipitate are used for the prevention and treatment of bleeding.

Usefulness of standard plasma coagulation tests in the management of perioperative coagulopathic bleeding: is there any evidence?

Standard laboratory coagulation tests (SLTs) such as prothrombin time/international normalized ratio or partial thromboplastin time are frequently used to assess coagulopathy and to guide haemostatic interventions. However, this has been challenged by numerous reports, including the current European guidelines for perioperative bleeding management, which question the utility and reliability of SLTs in this setting. Furthermore, the arbitrary definition of coagulopathy (i.e. SLTs are prolonged by more than 1.5-fold) has been questioned. The present study aims to review the evidence for the usefulness of SLTs to assess coagulopathy and to guide bleeding management in the perioperative and massive bleeding setting. Medline was searched for investigations using results of SLTs as a means to determine coagulopathy or to guide bleeding management, and the outcomes (i.e. blood loss, transfusion requirements, mortality) were reported. A total of 11 guidelines for management of massive bleeding or perioperative bleeding and 64 studies investigating the usefulness of SLTs in this setting were identified and were included for final data synthesis. Referenced evidence for the usefulness of SLTs was found in only three prospective trials, investigating a total of 108 patients (whereby microvascular bleeding was a rare finding). Furthermore, no data from randomized controlled trials support the use of SLTs. In contrast, numerous investigations have challenged the reliability of SLTs to assess coagulopathy or guide bleeding management. There is actually no sound evidence from well-designed studies that confirm the usefulness of SLTs for diagnosis of coagulopathy or to guide haemostatic therapy.

On the value of routine prothrombin time screening in elective neurosurgical procedures

Object

The authors performed a study to evaluate whether preoperative assessment of prothrombin time (PT) is mandatory in patients undergoing routinely planned neurosurgical procedures.

Methods

The charts of all patients admitted to general wards of the authors' department for routinely planned surgery (excluding trauma and ICU patients) between 2006 and 2010 were retrospectively reviewed. The authors assessed preoperative PT and the clinical courses of all patients, with special consideration for patients receiving coagulation factor substitution. All cases involving hemorrhagic complications were analyzed in detail with regard to pre- and postoperative PT abnormalities. Prothrombin time was expressed as the international normalized ratio, and values greater than 1.28 were regarded as elevated.

Results

Clinical courses and PT values of 4310 patients were reviewed. Of these, 33 patients (0.7%) suffered hemorrhagic complications requiring repeat surgery. Thirty-one patients (94%) had a normal PT before the initial operation, while 2 patients had slightly elevated PT values of 1.33 and 1.65, which were anticipated based on the patient's history. In the latter 2 cases, surgery was performed without prior correction of PT. Preoperatively, PT was elevated in 78 patients (1.8%). In 73 (93.6%) of the 78 patients, the PT elevation was expected and explained by each patient's medical history. In only 5 (0.1%) of 4310 patients did we find an unexpected PT elevation (mean 1.53, range 1.37–1.74). All 5 patients underwent surgery without complications, while 2 had received coagulation factor substitution preoperatively, as requested by the surgeon, because of an estimated risk of bleeding complications. None of the 5 patients received coagulation factor substitution postoperatively, and later detailed laboratory studies ruled out single coagulation factor deficiencies. There was no statistically significant association between preoperatively elevated PT levels and the occurrence of hemorrhagic complications (p = 0.12). Before the second procedure but not before the initial operation, 4 (12%) of the 33 patients had elevated PT.

Conclusions

The findings suggest that the value of preoperative PT testing is limited in patients in whom a normal history can be ascertained. Close postoperative PT control is necessary in every neurosurgical patient, and better tests need to be developed to identify patients who are prone to hemorrhagic complications.

The Baboon (Papio spp.) as a model of human Ebola virus infection

Baboons are susceptible to natural Ebola virus (EBOV) infection and share 96% genetic homology with humans. Despite these characteristics, baboons have rarely been utilized as experimental models of human EBOV infection to evaluate the efficacy of prophylactics and therapeutics in the United States. This review will summarize what is known about the pathogenesis of EBOV infection in baboons compared to EBOV infection in humans and other Old World nonhuman primates. In addition, we will discuss how closely the baboon model recapitulates human EBOV infection. We will also review some of the housing requirements and behavioral attributes of baboons compared to other Old World nonhuman primates. Due to the lack of data available on the pathogenesis of Marburg virus (MARV) infection in baboons, discussion of the pathogenesis of MARV infection in baboons will be limited.

Blood component support in acquired coagulopathic conditions: is there a method to the madness?

Acquired coagulopathies are often detected by laboratory investigation in clinical practice. There is a poor correlation between mild to moderate abnormalities of laboratory test and bleeding tendency. Patients who are bleeding due to coagulopathy are often managed with various blood components including plasma, platelets, and cryoprecipitate. However, prophylactic transfusion of these products in a nonbleeding patient to correct mild to moderate abnormality of a coagulation test especially preprocedure is not evidence-based. This article reviews the management of bleeding due to oral anticoagulants and antiplatelet agents, disseminated intravascular coagulation, chronic liver disease, and trauma.

Intracranial pressure: why we monitor it, how to monitor it, what to do with the number and what's the future?

PURPOSE OF REVIEW

The review touches upon the current physiopathological concepts relating to the field of intracranial pressure (ICP) monitoring and offers an up-to-date overview of the ICP monitoring technologies and of the signal-analysis techniques relevant to clinical practice.

RECENT FINDINGS

Improved ICP probes, antibiotic-impregnated ventricular catheters and multimodality, computerized systems allow ICP monitoring and individualized optimization of brain physiology. Noninvasive technologies for ICP and cerebral perfusion pressure assessment are being tested in the clinical arena. Computerized morphological analysis of the ICP pulse-waveform can provide an indicator of global cerebral perfusion.

SUMMARY

Current recommendations for the management of traumatic brain injury indicate ICP monitoring in patients who remain comatose after resuscitation if the admission computed tomography scan reveals intracranial abnormalities such as haematomas, contusions and cerebral oedema. The most reliable methods of ICP monitoring are ventricular catheters and intraparenchymal systems. A growing number of these devices are being safely placed by neurointensivists. The consensus is to treat ICP exceeding the 20 mmHg threshold, and to target cerebral perfusion pressure between 50 and 70 mmHg. Recent evidence suggests that such thresholds should be optimized based on multimodality monitoring and individual brain physiology. Noninvasive ICP estimation using transcranial Doppler can have a role as a screening tool in patients with low to intermediate risk of developing intracranial hypertension. However, the technology remains insufficiently accurate and too cumbersome for continuous ICP monitoring.