New Uses for Thromboelastography and Other Forms of Viscoelastic Monitoring in the Emergency Department: A Narrative Review.

Patients frequently visit the emergency department with conditions that place them at risk of worse outcomes when accompanied by coagulopathy. Routine tests of coagulation-prothrombin time, partial thromboplastin time, platelets, and fibrinogen-have shortcomings that limit their use in providing emergency care. One alternative is to investigate coagulation disturbance with viscoelastic monitoring (VEM), a coagulation test that measures the timing and strength of blood clot development in real time. VEM is widely used and studied in cardiac surgery, liver transplant surgery, anesthesia, and trauma. In this article, we review the technique of VEM and the biologic rationale of using it in addition to routine tests of coagulation in emergency clinical situations. Then, we review the evidence (or lack thereof) for using VEM in the diagnosis and treatment of specific conditions. Finally, we describe the limitations of the test and future directions for clinical use and research in emergency medicine.

Interrelationship of preoperative anemia, intraoperative anemia, and red blood cell transfusion as potentially modifiable risk factors for acute kidney injury in cardiac surgery: a historical multicentre cohort study.

PURPOSE: Acute kidney injury (AKI) is a potentially serious complication of cardiac surgery. Anemia and red blood cell (RBC) transfusion have individually been identified as potentially modifiable risk factors, but their interrelationship with AKI has not been clearly defined. The purpose of this study was to explore the interrelationship of preoperative anemia, intraoperative anemia, and RBC transfusion on the day of surgery with AKI in cardiac surgery. METHODS: This historical cohort study included 16 hospitals, each contributing data on approximately 100 consecutive patients who underwent cardiac surgery with cardiopulmonary bypass. Acute kidney injury was defined as a > 50% increase in creatinine levels during the first postoperative week. Multivariable regression was used to identify the interrelationship between preoperative anemia (hemoglobin < 130 g·L(-1) in males and < 120 g·L(-1) in females), intraoperative anemia (hemoglobin < 80 g·L(-1) during cardiopulmonary bypass), RBC transfusion on the day of surgery, and their interaction terms, after adjusting for site and baseline AKI risk. RESULTS: Of the 1,444 patients included in the study, 541 (37%) had preoperative anemia, 501 (35%) developed intraoperative anemia, 619 (43%) received RBC transfusions, and 238 (16%) developed AKI. After risk-adjustment, an individual with the combination of these three risk factors had a 2.6-fold (95% confidence interval 2.0 to 3.3) increase in the relative risk of AKI over an individual with none of these risk factors. CONCLUSIONS: Preoperative anemia, intraoperative anemia, and RBC transfusion on the day of surgery are interrelated risk factors for AKI after cardiac surgery. Targeting these risk factors may reduce the burden of AKI.

Echocardiographic anatomy of the mitral valve: a critical appraisal of 2-dimensional imaging protocols with a 3-dimensional perspective.

OBJECTIVE: To highlight the limitations of traditional 2-dimensional (2D) echocardiographic mitral valve (MV) examination methodologies, which do not account for patient-specific transesophageal echocardiographic (TEE) probe adjustments made during an actual clinical perioperative TEE examination. DESIGN: Institutional quality-improvement project. SETTING: Tertiary care hospital. PARTICIPANTS: Attending anesthesiologists certified by the National Board of Echocardiography. INTERVENTION: Using the technique of multiplanar reformatting with 3-dimensional (3D) data, ambiguous 2D images of the MV were generated, which resembled standard midesophageal 2D views. Based on the 3D image, the MV scallops visualized in each 2D image were recognized exactly by the position of the scan plane. Twenty-three such 2D MV images were created in a presentation from the 3D datasets. Anesthesia staff members (n = 13) were invited to view the presentation based on the 2D images only and asked to identify the MV scallops. Their responses were scored as correct or incorrect based on the 3D image. METHODS AND MAIN RESULTS: The overall accuracy was 30.4% in identifying the MV scallops. The transcommissural view was identified correctly >90% of the time. The accuracy of the identification of A1, A3, P1, and P3 scallops was <50%. The accuracy of the identification of A2P2 scallops was ≥50%. CONCLUSION: In the absence of information on TEE probe adjustments performed to acquire a specific MV image, it is possible to misidentify the scallops.

Cardiac output monitoring: is there a gold standard and how do the newer technologies compare?

As a principal determinant of oxygen delivery and of blood pressure, cardiac output (CO) represents an important hemodynamic variable. Its accurate measurement, therefore, is important to the clinician caring for critically ill patients in a variety of care environments. Though the first clinical measurement of CO occurred 70 years ago, it was the introduction of the pulmonary artery catheter (PAC) with thermodilution-based determination of CO in the 1970s that set the stage for practical and widespread clinical measurement of CO. Although the usefulness and accuracy of this technique have justified its consideration as a "practical" gold standard in CO measurement, its drawbacks have driven the search for newer, less invasive measurement techniques. The last decade has seen the introduction of several such devices into the clinical arena. This article will serve to give a brief review of the history of CO measurement, to provide a discussion of the measurement of accuracy as it relates to CO measurement, and to discuss some of the newer methods and devices for CO measurement and how they have fared against a "practical" gold standard.

Changes in mitral valve annular geometry after repair: saddle-shaped versus flat annuloplasty rings.

BACKGROUND: Saddle-shaped annuloplasty rings are being increasingly used during mitral valve (MV) repair to conform the mitral annulus to a more nonplanar shape and possibly reduce leaflet stress. In this study utilizing three-dimensional transesophageal echocardiography we compared the effects of rigid flat rings with those of the saddle rings on the mitral annular geometry. Specifically we measured the changes in nonplanarity angle (NPA) before and after MV repair. METHODS: Geometric analysis on 38 patients undergoing MV repair for myxomatous and ischemic mitral regurgitation with full flat rings (n = 18) and saddle rings (n = 18) were performed. The acquired three-dimensional volumetric data were analyzed utilizing the "Image Arena" software (TomTec GmBH, Munich, Germany). Specifically, the degree of change in the NPA was calculated and compared before and after repair for both types of rings. RESULTS: Both types of annuloplasty rings resulted in significant changes in the geometric structure of the MV after repair. However, saddle rings lead to a decrease in the NPA (7% for ischemic and 8% for myxomatous MV repairs) (ie, made the annulus more nonplanar), whereas flat rings increased the NPA (7.9% for ischemic and 11.8% for myxomatous MV repairs) (ie, made the annulus less nonplanar); p value 0.001 or less. CONCLUSIONS: Implantation of saddle-shaped rings during MV repair surgery is associated with augmentation of the nonplanar shape of the mitral annulus (ie, decreases NPA). This favorable change in the mitral annular geometry could possibly confer a structural advantage to MV repairs with the saddle rings.

Management of a patient with lupus anticoagulant and antiphospholipid syndrome for off-pump coronary artery bypass grafting using the Hepcon system.

Patients with serum lupus anticoagulant antibodies (LAC) with or without antiphospholipid syndrome who present for cardiac surgery provide a unique set of challenges. Chief among these are the interference with anticoagulation monitoring by LAC. We present a case of such a patient who presented to us for coronary artery bypass grafting. We follow with a review of LAC and antiphospholipid syndrome and present a strategy for ensuring adequate anticoagulation during cardiac surgery in the background of previously published reports.

Intraoperative application of geometric three-dimensional mitral valve assessment package: a feasibility study.

OBJECTIVE: To study the feasibility of using 3-dimensional (3D) echocardiography in the operating room for mitral valve repair or replacement surgery. To perform geometric analysis of the mitral valve before and after repair. DESIGN: Prospective observational study. SETTING: Academic, tertiary care hospital. PARTICIPANTS: Consecutive patients scheduled for mitral valve surgery. INTERVENTIONS: Intraoperative reconstruction of 3D images of the mitral valve. RESULTS: One hundred and two patients had 3D analysis of their mitral valve. Successful image reconstruction was performed in 93 patients-8 patients had arrhythmias or a dilated mitral valve annulus resulting in significant artifacts. Time from acquisition to reconstruction and analysis was less than 5 minutes. Surgeon identification of mitral valve anatomy was 100% accurate. CONCLUSIONS: The study confirms the feasibility of performing intraoperative 3D reconstruction of the mitral valve. This data can be used for confirmation and communication of 2-dimensional data to the surgeons by obtaining a surgical view of the mitral valve. The incorporation of color-flow Doppler into these 3D images helps in identification of the commissural or perivalvular location of regurgitant orifice. With improvements in the processing power of the current generation of echocardiography equipment, it is possible to quickly acquire, reconstruct, and manipulate images to help with timely diagnosis and surgical planning.

Transmitral flow propagation velocity and assessment of diastolic function during abdominal aortic aneurysm repair.

INTRODUCTION: In the perioperative arena, pronounced changes in cardiac loading conditions can make assessment of diastolic parameters difficult. A number of Doppler techniques have been introduced to assess perioperative diastolic function. OBJECTIVES: To compare transmitral flow propagation velocity (Vp) with other pulse-wave Doppler echocardiographic assessments of diastolic function in patients undergoing elective abdominal aortic aneurysm (AAA) resection. DESIGN: A prospective observational study. STUDY SUBJECTS: Forty-five consecutive patients undergoing elective AAA repair under general anesthesia. METHODS: Transesophageal echocardiographic examination was performed before, during, and after removal of the aortic cross-clamp (AXC). Diastolic function was categorized on the basis of the ratio of transmitral pulse-wave Doppler (PWD) into early (E) and late (A) waves and their ratio (E/A), deceleration time, and use of pulmonary venous inflow patterns to identify pseudonormal pattern. Subjects were then assessed by using the Canadian Consensus Guidelines (CCG) and on the basis of transmitral flow Vp. The correlation among methods for diagnosis of diastolic dysfunction and pseudonormal pattern was examined. Diastolic function over each of the 3 periods to assess changes during AXC was examined. RESULTS: Data analysis was completed in 35 patients. The authors found excellent correlation between E/A ratio and Vp for diagnosis of diastolic dysfunction (24/25 cases) and a pseudonormal pattern (18/20 cases). The CCG methodology identified fewer cases of diastolic dysfunction than Vp (p = 0.003). The evaluation using CCG methodology could not be categorized in 15% of cases. The incidence of diastolic dysfunction increased during placement of AXC with both Vp and CCG (p < 0.05) but not by E/A ratio, and returned to baseline after removal of the AXC. Good correlation was found among all 3 methods (p < 0.05 and r > 0.5 for all). CONCLUSION: Vp assessment identified the majority (93%) of cases of diastolic dysfunction identified by traditional methods. Furthermore, the incidence of diastolic dysfunction increased with application of the AXC but returned to baseline after removal.