Annette Rebel

The Accuracy of Point-of-Care Glucose Measurements

Control of blood glucose (BG) in an acceptable range is a major therapy target for diabetes patients in both the hospital and outpatient environments. This review focuses on the state of point-of-care (POC) glucose monitoring and the accuracy of the measurement devices. The accuracy of the POC glucose monitor depends on device methodology and other factors, including sample source and collection and patient characteristics. Patient parameters capable of influencing measurements include variations in pH, blood oxygen, hematocrit, changes in microcirculation, and vasopressor therapy. These elements alone or when combined can significantly impact BG measurement accuracy with POC glucose monitoring devices (POCGMDs). In general, currently available POCGMDs exhibit the greatest accuracy within the range of physiological glucose levels but become less reliable at the lower and higher ranges of BG levels. This issue raises serious safety concerns and the importance of understanding the limitations of POCGMDs. This review will discuss potential interferences and shortcomings of the current POCGMDs and stress when these may impact the reliability of POCGMDs for clinical decision-making.

Transesophageal Echocardiography for the Noncardiac Surgical Patient

Transesophageal echocardiography (TEE) has been established as a very valuable asset for patient monitoring during cardiac surgery. The value of perioperative TEE for patients undergoing noncardiac surgery is less clear. This article reviews the technical aspects of TEE and comments on the potential benefit of using TEE as a monitoring modality apart from cardiac surgery. Based on patients comorbidities and/or injury pattern, TEE is a fast and minimally invasive approach to obtain important hemodynamic information, especially useful in a hemodynamically unstable patient. However, certain requirements for the use of the technique are necessary, most important the development of sufficient echocardiographic skills by the anesthesiologists. Indications, skill requirements, and possible complications of the technique are reviewed.

In situ immunoradiographic method for quantification of specific proteins in normal and ischemic brain regions.

This study tested the application of an immunoisotopic assay for immunohistochemical localization and quantification of proteins in brain sections from rats without or with transient focal ischemia. We assessed the hypothesis that measurements of protein levels in injured brain determined by an isotopic assay using [(125)I]-protein A have greater reliability than those made by conventional immunoperoxidase labeling using diaminobenzidine. Quantification of immunoreactivities for glial fibrillary acidic protein (GFAP), glutamate transporter-1 (GLT-1) and heat shock protein-70 (HSP-70) was determined by optical density signal in the immunoisotopic and immunoperoxidase assays. In ischemic brain, the immunoisotopic assay detected protein increases (cortical penumbra HSP-70, 151+/-6%), protein decreases (cortical ischemic core GLT-1, 61+/-6%) and no changes in GFAP levels compared to controls animals. These results differed from the protein levels found by the immunoperoxidase assay, which showed elevated HSP-70, GLT-1 and GFAP in all ischemic regions. We conclude that nonspecific immunosignal confounds assessments of protein expression in injured brain and that the immunoisotopic method is a valid approach to regionally localize and quantify proteins after brain injury. The disadvantage of the falsely positive overestimation of protein immunoreactivity after stroke with the immunoperoxidase method has to be weighted with the advantage of the cellular resolution.

How do we integrate thromboelastography with perioperative transfusion management

F or the foreseeable future, conventional coagulation testing will remain important for anticipation, intervention, and management of hemorrhage and thrombosis in surgical patients. Conventional tests used at our institution include platelet (PLT) count, prothrombin time (PT), activated partial thromboplastin time (aPTT), fibrinogen levels, sometimes other factor levels, and D-dimer. Activated clotting time (ACT; International Technidyne Corp., Edison, NJ) is a point-of-care (POC) test run in our operating room. However, today’s complex and prolonged operations increasingly require effective, targeted use of blood products and hemostasis-altering drugs, which in turn demands more complete and timely coagulation information than conventional testing typically provides. Inherently long turnaround times can render laboratory results irrelevant before they can be reported, creating demand for POC testing including ACT and PLT function screening assays such as the PLT function analyzer (PFA-100; Siemens USA, Washington, DC). POC testing has its own limitations, including cost, quality control (QC), equipment maintenance, and correlation with laboratory-based testing. Available, more sophisticated testing can do a better job for complex surgical patients in the operating room. Another limitation of most coagulation tests is their artificial, analytical nature, which isolates components of the hemostasis system under contrived laboratory conditions. The in vivo coagulation mechanism resembles an intricate ballet performed by flowing red blood cells (RBCs), PLTs, subendothelial proteins, and various circulating proenzymes and cofactors on a dynamic threedimensional stage of phospholipid bilayers and meshed fibrin strands, resulting in a clot that stanches hemorrhage, remains localized to the site of injury, and gradually dissolves as healing proceeds. No in vitro coagulation test will ever do full justice to the in vivo system. While also artificial, whole blood thromboelastography (TEG) nevertheless more closely mimics physiologic hemostasis, providing specific information about coagulation status in real time, and it is currently used extensively at our institution to guide specific interventions with blood product replacement and drug therapy. The basic technology was developed by Hartert in the late 1940s, but was not widely used until much more recently. Two versions of this technique are currently available: TEG (Haemonetics Corp., Braintree, MA) and ROTEM (Tem International GmbH, Munich, Germany). A third method, Sonoclot (Sienco, Inc., Arvada, CO), employs a slightly different clot detection principle. This article will focus on TEG because we currently use it at our institution (Fig. 1). The test is conceptually simple. In our laboratory, a small quantity of fresh citrated whole blood is mixed with kaolin and excess calcium, much as in the aPTT, except that in TEG, the RBCs and PLTs remain to fulfill their physiologic roles. The multiple variables of TEG include not only the time to initial clot detection (the sole endpoint of the aPTT) but also the subsequent rate of clotting, the strength of the clot over time, and the rate and degree of clot lysis. Since both the primary (PLT-related) and the secondary (factor-related) components of hemostasis participate in the reaction, the features of the curve can identify and guide management of thrombocytopenia, factor deficiencies, hypofibrinogenemia, fibrinolysis, or inappropriate dosing of hemostasis-altering agents. At our institution, we primarily use citrated whole blood samples. Versions of TEG using citrated or very fresh uncitrated blood with or without kaolin are available as ABBREVIATIONS: ACT = activated clotting time; aPTT = activated partial thromboplastin time; CPB = cardiopulmonary bypass; LMWH = low-molecular-weight heparin; MA = maximum amplitude; PT = prothrombin time; R time = reaction time; TEG = thromboelastography.

Initial results of a structured rotation in hematology and transfusion medicine for anesthesiology residents.

STUDY OBJECTIVE To develop and evaluate a new curriculum in transfusion medicine for anesthesiology residents. STUDY DESIGN Quasi-experimental study. SETTING Single center, pilot curriculum in the anesthesiology residency program at a university-affiliated medical center. PARTICIPANTS Group TM consisted of residents who participated in the one month-long transfusion medicine rotation in postgraduate year 2 (PGY2; n = 9). The comparison group (non-TM) consisted of residents who had no exposure to the transfusion medicine rotation (n = 21). MEASUREMENTS We compared results of the 2009 American Board of Anesthesiology In-Training Exam (ABA-ITE) 2009 by residents of our program with the national performance of residents in the first clinical anesthesia year (AMG CA1 = PGY-2) and second clinical anesthesia year (AMG CA2 = PGY-3) on transfusion medicine/hematology knowledge. Performance on a pre-test and post-test of those who took part in the transfusion medicine curriculum, and overall performance on the ABA-ITE, of departmental residents who had and had not participated in the Transfusion Medicine curriculum within the target knowledge area of hematology/transfusion medicine and compared against national peer performance data, was assessed. An anonymous electronic survey (5-Point Likert scale) was used to assess the perceived educational value of the curriculum. MAIN RESULTS Transfusion medicine-related knowledge of anesthesia residents markedly improved from the pre- to post-rotation examination and on the ABA-ITE. In the ABA-ITE 2009, the TM group performed better than their national peers (AMG CA1 and CA2) in the hematology content area. The post-rotation anonymous resident survey indicated high resident satisfaction. CONCLUSIONS A structured transfusion medicine curriculum improved anesthesiology resident knowledge in transfusion medicine and was associated with high learner satisfaction.

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.

Retrospective analysis of high-dose intrathecal morphine for analgesia after pelvic surgery.

BACKGROUND The effectiveness of intrathecal opioids (ITOs) for postoperative analgesia has been limited by reduced opioid dosing because of opioid-related side effects, most importantly respiratory depression. To overcome these limitations, high-dose intrathecal morphine was combined with a continuous intravenous (IV) postoperative naloxone infusion. The aim of the present chart analysis was to investigate the safety and efficacy of high-dose ITOs combined with IV naloxone compared with IV opioid analgesia alone. METHODS A retrospective chart analysis was performed on 121 female patients requiring major pelvic surgery. Ninety-eight patients received a single injection of high-dose ITOs before administration of typical general anesthesia, followed by an IV naloxone infusion at 5 µg⁄kg⁄h started post-ITO and continued for 22 h postoperatively. Twenty-three patients were given IV morphine (IVM) for postoperative analgesia and served as a reference group. Postoperative pain relief, analgesic consumption and ability to ambulate were assessed for 48 h postoperatively. Treatment safety was assessed by monitoring opioid-related side effects and vital signs. Data are presented as mean ± SD. RESULTS Mean ITOs given were morphine 1.1±0.2 mg combined with fentanyl 49 ± 6 µg. The mean worst pain visual analogue scale score in the first 12 h postoperatively was 0.2 ± 0.90 in the ITO group versus 4.3 ± 3.0 in the IVM group (P<0.05). On postoperative day 2, the mean worst pain visual analogue scale score was only 1 ± 1.8 in the ITO group versus 4.1 ± 2.6 in the IVM group (P<0.05). Analgesic requirements were reduced in the ITO group. In the first 24 h, the ITO group used 6.8±10.2 morphine equivalents (mg IV) versus 76.1 ± 44.4 in the IVM group (P<0.05). All patients in the ITO group were able to ambulate in the first 12 h postoperatively compared with 17⁄23 in the IVM group. There was a higher incidence of opioid-related sedation in the IVM group. Other opioid-related side effects were infrequent and minor in both groups. CONCLUSIONS High-dose ITOs combined with a postoperative IV naloxone infusion provided excellent analgesia for major pelvic surgery. The IV naloxone infusion combined with high-dose ITOs appeared to control opioid side effects without affecting analgesia.

Neurophysiological monitoring simulation using flash animation for anesthesia resident training.

Introduction: Surgery of the spine is associated with the possible complication of permanent nerve injury. Neurophysiological monitoring is widely used during spine surgery to decrease the incidence and severity of neurologic injury. A profound understanding of physiological and pharmacological factors influencing evoked potentials is expected from the anesthesia provider. Methods: Because demonstration and teaching of all somatosensory evoked potential (SSEP) changes is difficult in the clinical environment, we developed human patient simulator scenarios to facilitate the anesthesia resident training in neurophysiological monitoring. A SSEP simulation for resident training was created using flash animation in a patient simulation program and is the focus of this report. Feedback from participants (anesthesia residents) was obtained by a postscenario survey. Results: This report provides a detailed description of the scenario and computer program. The survey findings indicated that the simulation session is an effective teaching method of SSEP monitoring. Conclusion: Flash animation integration into a patient simulation program for SSEP monitoring appears to be an effective method for anesthesia resident education in neurophysiological monitoring.

The Impact of Exposure to Liver Transplantation Anesthesia on the Ability to Treat Intraoperative Hyperkalemia: A Simulation Experience

The objective of this study was to assess whether resident exposure to liver transplantation anesthesia results in improved patient care during a simulated critical care scenario. Our hypothesis was that anesthesia residents exposed to liver transplantation anesthesia care would be able to identify and treat a simulated hyperkalemic crisis after reperfusion more appropriately than residents who have not been involved in liver transplantation anesthesia care. Participation in liver transplantation anesthesia is not a mandatory component of the curriculum of anesthesiology training programs in the United States. It is unclear whether exposure to liver transplantation anesthesia is beneficial for skill set development. A high-fidelity human patient simulation scenario was developed. Times for administration of epinephrine, calcium chloride, and secondary hyperkalemia treatment were recorded. A total of 25 residents with similar training levels participated: 13 residents had previous liver transplantation experience (OLT), whereas 12 residents had not been previously exposed to liver transplantations (non-OLT). The OLT group performed better in recognizing and treating the hyperkalemic crisis than the non-OLT group. Pharmacologic therapy for hyperkalemia was given earlier (OLT 53.3 ± 27.0 seconds versus non-OLT 148 ± 104.1 seconds; P < 0.01) and hemodynamics restored quicker (OLT 87.9 ± 24.9 seconds versus non-OLT 219.9 ± 87.1 seconds; P < 0.01). Simulation-based assessment of clinical skills is a useful tool for evaluating anesthesia resident performance during an intraoperative crisis situation related to liver transplantations. Previous liver transplantation experience improves the anesthesia residents ability to recognize and treat hyperkalemic cardiac arrest.

Dilemma during ultrasound‐guided internal jugular venous catheterization

The presence of Internal Jugular Valves can pose a diagnostic and procedural challenge during ultrasound‐guided cannulation. After ruling out dissection, thrombus, or ultrasound artifacts, it can still be accessed and successfully cannulated with appropriate precautions including use of Live ultrasound, positioning, use of soft‐tipped catheters, and minimizing duration of catheter placement.