Background:Patients with atrial fibrillation (AF) remain at increased risk of thromboembolism despite apparent maintenance of sinus rhythm with the cause often attributed to periods of asymptomatic AF. Atrial mechanical discordance, with the body of the left atrium (LA) in sinus rhythm and the left atrial appendage (LAA) in AF may also be a contributor. Objectives:The purpose of this study was to assess the frequency of electrocardiogram (ECG) rhythm and LAA and/right atrial appendage (RAA) Doppler ejection phenotype (transesophageal echocardiography [TEE]) discordance in patients undergoing cardiac surgery. Methods:A total of 124 patients undergoing coronary artery bypass graft (CABG), CABG and valve surgery, or isolated valve repair or replacement (valve ± CABG) were prospectively studied. Intraoperative surface ECG rhythm strip and TEE were performed before cardiopulmonary bypass. The ECG and TEE LAA/RAA Doppler spectrum were independently classified as sinus or AF. Results:Of 107 patients (age 65 ± 12 years; 31% female; 65% CABG, 31% valve ± CABG) without a history of AF, 39 (36%) had ECG and LAA and/or RAA discordance (ECG/LAA Doppler discordance, n = 12 [11%]; ECG/RAA Doppler discordance, n = 35 [33%]). There was no significant difference between concordant and discordant groups with regard to age, gender, history of hypertension, diabetes, heart failure, or stroke (all P > 0.05). Conclusions:A large minority of patients without a history of AF undergoing cardiac surgery have ECG/atrial appendage Doppler discordance, a setting that may promote thromboembolism in non-anticoagulated patients. Clinical parameters do not identify patients at increased risk for discordance.

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. 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.

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.

Introduction: Post-operative atrial fibrillation (POAF) after cardiac surgery is associated with increased length of stay and long-term risk of stroke. Identification of at-risk patients is therefo...

We greatly enjoyed reading the recent review by Dr Nogami (Nogami, 2016). However, we noted there was no specific mention of von Willebrand disease (VWD). We present a patient with VWD sheduled to undergo cardiac surgery in which TEG was used to successfully guide the intraoperative dosing of VWF concentrate. Testing to diagnose and manage VWD includes measurement of von Willebrand factor (VWF) antigen (VWF:Ag), ristocetin cofactor activity (VWF:RCo) and factor VIII (FVIII) activity levels (FVIII:C). Patients with acquired VWD undergoing major surgery are at increased risk for bleeding and require prophylactic administration of VWF concentrate. However, the monitoring of these patients during surgery poses a challenge: In most laboratories, turn-around times for factor assays preclude use in ‘real-time’ decision-making. While the activated partial thromboplastin time (APTT) may also be prolonged in patients with VWD due to loss of FVIII activity, heparin used during bypass surgery limits utility. Four years prior to surgery, a 75-year-old male presented with recurrent haematuria and rectal bleeding attributed to radiation cystitis and proctitis. He was found to have a mildly elevated APTT that ranged from 36·2 to 45·6 s (reference range: 22–35 s) and a normal prothrombin time (PT). The patient had no personal or family history of coagulopathy and had undergone hip replacement in the past without any bleeding complications. On further testing, FVIII:C was 5–15% (normal 50–200%), VWF:Ag was 16% (normal 50–180%) and VWF:RCo was <12·5% (normal 50–200%). He was diagnosed with acquired VWD. A year later, an echocardiogram demonstrated moderate aortic stenosis (AS) (mean gradient: 28 mm Hg). Over the ensuing 3 years, his AS progressed to severe (mean gradient: >60 mm Hg) and was associated with worsening shortness of breath. As a consequence, he was scheduled to undergo surgical aortic valve replacement (AVR). To better understand the contribution of the aortic stenosis to his acquired VWD, a multimer analysis showed a normal pattern and distribution of bands, while aortic stenosis-associated VWD typically leads to a loss of high-molecular weight multimers (Vincentelli et al, 2003). In preparation for surgery, a cardiac catheterization was performed after a single dose of VWF/FVIII concentrate (Humate-P; CSL-Behring, King of Prussia, PA, USA). Immediately after a dose of 30 units/kg ristocetin cofactor (RCo, expected to raise the VWF activity level by approximately 60%), his VWF:Ag rose from 13% to 101%, VWF activity from <10·5% to 71%, and FVIII:C from 6% to 44%, but these levels dropped by over 50% four hours later. A plan was developed between anesthesiology, haematology and laboratory medicine to administer high dose Humate-P for the AVR. In the operating room (OR), following collection of baseline TEG, APTT, VWF:Ag, FVIII levels and VWF:RCo, 107 RCo units/kg of Humate-P (expected to raise the VWF and FVIII levels by ~200% and ~100% respectively) would be administered with plans to give an empiric second dose immediately after protamine administration. Although the haematology laboratory planned for ‘stat’ VWF and FVIII testing after Humate-P and protamine administration, given the nature of these assays it was not expected the results would return in time to affect intraoperative management. The APTT results, while available more rapidly, would be elevated by the heparin used during the bypass procedure. As such, the plan included monitoring of coagulation during surgery via TEG. TEG is a point-of-care, whole blood, viscoelastic coagulation assay, which provides information regarding the function of the patient's coagulation factors, fibrinogen, and platelets in clot formation and breakdown (Bolliger et al, 2012). Although a full TEG profile may take 30 min or longer to develop, useful information is available within 5–10 min of test initiation. Furthermore, TEG assays can be run with heparinase so as to remove the effect of the heparin used on cardiopulmonary bypass (CPB). After the baseline samples were obtained, the patient received his first dose of Humate-P, reconstituted in the OR, prior to heparin administration. The baseline TEG showed an increased reaction (R)-time of 13·2 min, consistent with the decrease in FVIII and prolonged APTT at baseline (Fig 1A,C). After administration of Humate-P, the R-time decreased to 6·3 min, consistent with normalization of FVIII and APTT. Of note, the TEG result was available within 10 min after injection of Humate-P. The decision on whether to give additional Humate-P was made during the rewarming period while the patient was on bypass and fully heparinized. Using the TEG with heparinase assay, the R-time remained in the normal reference range at 8·2 min and, as a consequence, the Humate-P was not reconstituted (Fig 1A,B). Another TEG result obtained 5 min after protamine administration showed return of the R-time to levels close to the pre-surgery/post-Humate-P timepoint, corroborating that an additional dose of Humate-P was not necessary. At no point did the operative team experience any difficulty with haemostasis. The first VWF laboratory values after the administration of Humate-P only became available after the patient was already off CPB and the surgery was close to completion (Fig 1B). This indicates that, even though there was a substantial amount of organization and work to improve ‘stat’ coagulation analysis in the laboratory, the results were still not available in time to affect patient care. Surprisingly, FVIII levels post-surgery increased to 247%, further than expected based on prior in vivo recovery estimates. In addition, the rate of FVIII and VWF level decline was slower than previously observed. Although these levels eventually dropped to his previous baseline, subsequent Humate-P infusions for recurrent haematuria continued to indicate improved in vivo recovery. These results suggest that AS may have been playing some role in the patient's acquired VWD. This case provides useful information regarding management of patients with clotting factor deficiencies undergoing complex surgery. While the use of TEG for monitoring patients with VWD during surgery has been reported before (Tuman et al, 1987; Pivalizza, 2003), to our knowledge, this is the first report describing a patient with acquired VWD. In this setting, responses to clotting factor concentrates are much less predictable than in congenital deficiencies and obtaining rapid coagulation testing results is even more critical. By using TEG, we were able to obtain ‘real-time’ results on a heparinized patient to prevent an unnecessary empiric second dose of clotting factor concentrate, helping to conserve a scarce and expensive resource and preventing potential harm to the patient from receiving unnecessary treatment. All authors were involved in the care of the patient and developed the treatment plan together. M.S. and S.C. drafted the letter. S.S. and K.B. provided background information and specific values from the past medical history. All authors analysed and interpreted the clinical results and helped to finalise the manuscript.

A 67-YEAR-OLD MALE (height 183 cm, weight 100 kg) with a history of anterior myocardial infarction and cardiomyopathy (estimated ejection fraction of 20%-25%) presented for implantable cardioverter-defibrillator (ICD) lead extraction and single-chamber ICD reimplantation. At the time of presentation, his device was a single-chamber Medtronic Virtuoso ICD (Medtronic, Dublin, Ireland), which was implanted in 2007 for inducible ventricular tachycardia. The extraction was planned because the existing right ventricular (RV) Fidelis lead (Medtronic) had been placed on Food and Drug Administration advisory and the device battery was nearing elective replacement indications. His preoperative transthoracic echocardiogram showed severe regional left ventricular (LV) systolic dysfunction, with akinesis of the septum and severe hypokinesis of the mid-anterior wall and all distal LV segments. An apical LV aneurysm also was demonstrated on transthoracic echocardiography. The RV free wall displayed mild-to-moderate global hypokinesis. The valvular structure and function were normal. The patient was scheduled for an elective lead extraction under general anesthesia with cardiopulmonary bypass as standby. After an uneventful induction of general anesthesia, the esophagus was intubated with a transesophageal echocardiography (TEE) probe, and an intraoperative echocardiographic examination was performed with an X7-2t probe and a Philips iE33 ultrasound system (Philips Ultrasound, Andover, MA). Of note, before lead extraction, the RV displayed moderate-to-severe global free wall hypokinesis (Video 1, A). The procedure proceeded uneventfully until after the RV lead extraction. An immediate postextraction TEE examination demonstrated a flail tricuspid valve (TV) leaflet (septal or anterior) (Fig 1; Video 2). There also was an eccentric tricuspid regurgitation (TR) jet of severe intensity (see Fig 1, C; Video 1, B), with abnormal leftward interatrial septal deviation suggestive of elevated right atrial (RA) pressure (Fig 2; Video 2). Global RV systolic function seemingly improved because of the severe TR (Video 1, B,). In addition, color-flow Doppler demonstrated a simultaneous right-to-left shunt flow across the interatrial septum (Fig 3). This was associated with transient mild hypoxia (oxygen saturation 92% on 40% FIO2). The patient also experienced transient hypotension that responded to intermittent phenylephrine boluses (300 μg) and an epinephrine infusion (0.03-μg/kg/min).Fig 2Intraoperative transesophageal echocardiography, midesophageal 4-chamber view. Diastolic septal motion toward the left atrium due to elevated right atrial pressure.View Large Image Figure ViewerDownload Hi-res image Download (PPT)Fig 3Midesophageal bicaval view. Right-to-left atrial shunt due to high right atrial pressure and patent foramen ovale. Flow detected on color Doppler indicated by arrow.View Large Image Figure ViewerDownload Hi-res image Download (PPT) The echocardiographic challenges were as follows:1Establishing the exact nature and severity of injury to the TV.2Accurately assessing the severity of TR.3Excluding other intracardiac injuries. The clinical challenges were as follows:1Does the TV injury require immediate intervention?2If immediate intervention is not necessary, what clinical course should be taken? The electrophysiology team was informed immediately of this new echocardiographic finding and its clinical sequelae. A complete TEE examination also was performed to exclude other intracardiac injuries. After exclusion of other intracardiac injuries and clinical stabilization of the patient, it was decided mutually to keep the patient’s esophagus intubated for the time being and to monitor the course of the TR. The postoperative course was uneventful. The patient’s esophagus was extubated 24 hours later, and the patient was discharged home after two days and scheduled for additional follow-up echocardiograms. After implantation, ICD leads and surrounding intracardiac structures usually go through fibrotic encapsulation by the activation of different humoral and cellular mechanisms.1Esposito M. Kennergren C. Holmström N. et al.Morphologic and immunohistochemical observations of tissues surrounding retrieved transvenous pacemaker leads.J Biomed Mater Res. 2002; 63: 548-558Crossref PubMed Scopus (57) Google Scholar Therefore, complications such as pericardial tamponade, RV rupture, vascular damage, pulmonary embolism, and TV injury can occur periodically.2Coffey J.O. Sager S.J. Gangireddy S. et al.The impact of transvenous lead extraction on tricuspid valve function.Pacing Clin Electrophysiol. 2014; 37: 19-24Crossref PubMed Scopus (32) Google Scholar, 3Meier-Ewert H.K. Gray M.-E. John R.M. Endocardial pacemaker or defibrillator leads with infected vegetations: A single-center experience and consequences of transvenous extraction.Am Heart J. 2003; 146: 339-344Abstract Full Text Full Text PDF PubMed Scopus (96) Google Scholar, 4Fu H.-X. Huang X.-M. Zhong L.I. et al.Outcomes and complications of lead removal: Can we establish a risk stratification schema for a collaborative and effective approach?.Pacing Clin Electrophysiol. 2015; 38: 1439-1447Crossref PubMed Scopus (46) Google Scholar A high level of vigilance is required to detect and manage these possible complications during ICD extraction. Real-time TEE is an essential periprocedural imaging modality. Specifically, RV rupture can cause pericardial effusion and cardiac tamponade. The latter is a critical complication because it requires immediate intervention. Systolic RA or diastolic RV collapse and mitral valve inflow variation are used as diagnostic criteria. In the case of uncontrollable hemorrhage, RV repair is mandatory with cardiopulmonary bypass support. Disruption of the superior vena cava or brachiocephalic vein is a devastating complication because it results in immediate exsanguination in the thoracic cavity. Reconstruction with the patient under deep hypothermic circulatory arrest (18-20º C) and antegrade cerebral perfusion usually are mandatory. TV leaflet injury or elevated RV pressure due to pulmonary embolism can cause severe TR. A comprehensive echocardiographic valve analysis is essential when new-onset TR is diagnosed. Data regarding RV and pulmonary artery pressure, RV and RA dimensions, and RV systolic function need to be collected. However, life-threatening pulmonary embolism caused by vegetations derived from RV leads is rare.5Noheria A. Ponamgi S.P. Desimone C.V. et al.Pulmonary embolism in patients with transvenous cardiac implantable electronic device leads.Europace. 2016; 18: 246-252Crossref PubMed Scopus (20) Google Scholar The management strategy for severe TR caused by TV injury is less well defined. Patients responsive to resuscitation are eligible for postprocedural stabilization before a decision for intervention is made. According to the American Heart Association/American College of Cardiology guidelines for management of valvular heart disease, the indication for TV replacement/repair is determined by the patient’s symptoms and/or progression of RV dysfunction in the postoperative phase. Surgery in symptomatic patients can be beneficial if the patient’s condition is unresponsive to conservative management; in asymptomatic patients with progressive deterioration of RV function, surgery may be considered (level of evidence C).6Nishimura R.A. Otto C.M. Bonow R.O. et al.2014 AHA/ACC guideline for the management of patients with valvular heart disease.J Thorac Cardiovasc Surg. 2014; 148: e1-e132Abstract Full Text Full Text PDF PubMed Scopus (803) Google Scholar In conclusion, the management of complications caused by lead extraction can be challenging and is highly dependent on the patient’s condition. High-fidelity cardiac imaging using TEE is mandatory for quick and accurate diagnosis. eyJraWQiOiI4ZjUxYWNhY2IzYjhiNjNlNzFlYmIzYWFmYTU5NmZmYyIsImFsZyI6IlJTMjU2In0.eyJzdWIiOiI0YWI5YTBlN2ZkMzc5YTI4NGE1OWVkODFjODUwZDY2MyIsImtpZCI6IjhmNTFhY2FjYjNiOGI2M2U3MWViYjNhYWZhNTk2ZmZjIiwiZXhwIjoxNjc4MDIyOTgwfQ.nMeKSCNkw6Zw36bwVC_hN1Pp-Ul0wwIDv4yoFTFoW1nly34UUufv5fkV65Q9DYCylwIYLvkVcTXwk4UkOc8XQ6SFkBBgoDUHUetDe4c7c0f01oaCeyzTF6BROrI3-fEbjMQGrQmVRr2HniKHt2iQ42x5GIMHIRawvFAzewHMqrzBBqBpST1ElF-MgIQRO_YGkivVprzaBX8gI8Phs4Z20TduRTklVc24dvVZQdLkYn34U6KiiEsoXrUFvQr5rROdQvs8NaUctOqTO1At8iW7tyffsVbEZ7kkjDhIRAWlQmUSntsEWEMuqczgyuhqYLAoyim_4yy_z1mGkICcVRVAAQ Download .mp4 (39.27 MB) Help with .mp4 files Supplementary material: Video 1. (A) Midesophageal 4-chamber view. Before lead extraction, the right ventricular (RV) free wall displayed mild to moderate global hypokinesis. (B) Midesophageal 4-chamber view. Severe tricuspid regurgitation jet detected using color Doppler. Due to severe tricuspid regurgitation, the RV wall motion seemingly improved compared with the preprocedural state. eyJraWQiOiI4ZjUxYWNhY2IzYjhiNjNlNzFlYmIzYWFmYTU5NmZmYyIsImFsZyI6IlJTMjU2In0.eyJzdWIiOiJjOTMwMTIzYTMzOTc4MzZkOWU2NzQxYWY4M2FiYWMyNiIsImtpZCI6IjhmNTFhY2FjYjNiOGI2M2U3MWViYjNhYWZhNTk2ZmZjIiwiZXhwIjoxNjc4MDIyOTgwfQ.BnT8x9c1OBC72lIAMXKiVE8SCfJ4bObUU4vFSm-0RAPg5kRnnYukzx3UAfcDHgf77asRRjVhok5YP58a2tOhzhdE24fII5BSoMJ_mWDBYiJ-jsK53sjgMJtzkSqPPSlsLV4Gz66qEUkk8nA-nYoev0mbNubmM2mHgNhCb5EfC2Ez1ahSMQQTk6NgzzRQgx-DvCjyFaw_ZksdZSwUByDKVxwU_17A5kUwt5p2WQuOq1maL9BtkgJ7YcMNt6kkX4iWxVrLnyCsdYbFEozsTtZkiZDQJprL-oeNy5XgyZH8pcURAj_DMCU6ochuAjSAp8zg7ryNdaxKxXZLbA1sscxDdQ Download .mp4 (39.05 MB) Help with .mp4 files Supplementary material: Video 2. Midesophageal 4-chamber view. Flail tricuspid valve leaflet and interatrial septal deviation toward left atrium due to tricuspid regurgitation.

BACKGROUND:Thiamine is a vitamin that is essential for adequate aerobic metabolism. The objective of this study was to determine if thiamine administration prior to coronary artery bypass grafting would decrease post-operative lactate levels as a measure of increased aerobic metabolism.METHODS:We performed a randomized, double-blind, placebo-controlled trial of patients undergoing coronary artery bypass grafting. Patients were randomized to receive either intravenous thiamine (200 mg) or placebo both immediately before and again after the surgery. Our primary endpoint was post-operative lactate levels. Additional endpoints included pyruvate dehydrogenase activity, global and cellular oxygen consumption, post-operative complications, and hospital and intensive care unit length of stay.RESULTS:Sixty-four patients were included. Thiamine levels were significantly higher in the thiamine group as compared to the placebo group immediately after surgery (1200 [683, 1200] nmol/L vs. 9 [8, 13] nmol/L, p < 0.001). There was no difference between the groups in the primary endpoint of lactate levels immediately after the surgery (2.0 [1.5, 2.6] mmol/L vs. 2.0 [1.7, 2.4], p = 0.75). Relative pyruvate dehydrogenase activity was lower immediately after the surgery in the thiamine group as compared to the placebo group (15% [11, 37] vs. 28% [15, 84], p = 0.02). Patients receiving thiamine had higher post-operative global oxygen consumption 1 hour after the surgery (difference: 0.37 mL/min/kg [95% CI: 0.03, 0.71], p = 0.03) as well as cellular oxygen consumption. We found no differences in clinical outcomes.CONCLUSIONS:There were no differences in post-operative lactate levels or clinical outcomes between patients receiving thiamine or placebo. Post-operative oxygen consumption was significantly increased among patients receiving thiamine.TRIAL REGISTRATION:clinicaltrials.gov NCT02322892, December 14, 2014.

OBJECTIVESThe objective of this study was to characterize the association between lactate levels and hospital length of stay (LOS) after cardiac surgery.DESIGNA retrospective study using prospectively collected data from the Society of Thoracic Surgeons adult cardiac surgery database.SETTINGA tertiary-care hospital.PARTICIPANTSPatients in the database who presented for major cardiac surgery between 2002 and 2014 and whose lactate level was measured within 3 hours after skin closure.INTERVENTIONSNone.MEASUREMENTS AND MAIN RESULTSThe authors performed multivariable linear regression with adjustment for more than 30 variables to assess the association between postoperative lactate levels and hospital LOS. The study included 1,208 patients whose median LOS was 6 days (quartiles: 5, 9). Median LOS in the low-, moderate-, and high-lactate groups was 5 days (quartiles: 4, 7), 6 days (quartiles: 5, 9) and 9 days (quartiles: 6, 17), respectively; p<0.001. In multivariable analysis, patients with a moderate lactate level had a 1.08 times (95% CI: 1.00-1.17; p = 0.04) longer LOS compared with those with a low lactate level. Patients with a high lactate level had a 1.12 times (95% CI: 1.00-1.26; p = 0.04) longer LOS compared with those with a low lactate level. Lactate levels also were associated with intensive care unit LOS and nonsurgical postoperative complications.CONCLUSIONSPostoperative lactate levels are associated with increased hospital LOS for patients undergoing major cardiac surgery.

For more information, contact: Haobo Ma, MD, Department of Anesthesia hma@bidmc.harvard.edu The Problem Effective communication is critical to patient and family engagement in perioperative care. This team explored innovative ways to evaluate current perioperative processes and apply emerging technology to improve communication for patients and families from Holding Area through intraoperative care to PACU.

As the population ages, increasing numbers of elderly patients with multiple co-morbid conditions are presenting for high-risk cardiovascular surgical procedures. The commensurate increase in perioperative major adverse events (MAEs) increases mortality by 1.4 to 8-fold,1 with an estimated 1 billion dollars annually spent on managing these complications.2 Current MAE risk prediction indexes3,4 are typically based on static or “snapshot” measures, such as the presence or absence of a co-morbid condition like hypertension. Unfortunately, these indexes have failed to adequately predict which high-risk patients will have MAEs5–7 possibly, at least in part, because they do not take into consideration the complex (nonlinear), time-varying features of physiological hemodynamic signals. Furthermore, a “one-size-fits-all” risk prediction model approach is unlikely to accurately identify patients at high risk5–7 particularly at extremes of age and predicted risk.8–13 A major motivation for the program outlined here is that current risk prediction tools may be improved by incorporating dynamical properties of physiologic signals, thereby enhancing: (a) individual patient risk assessment and counseling, (b) design of timely interventions to prevent disabling or fatal complications (e.g., stroke, renal failure, atrial fibrillation and myocardial infarction), and (c) the accuracy of comparisons of provider and hospital performances. Toward this end, our goal is to develop a real-time blood pressure variability (BP variability) index or set of indexes incorporating a patient's own baseline and evolving pathophysiologic characteristics into current “snapshot” scoring systems.4,5,14 One of the most important physiologic signals obtained in the perioperative period is the continuously recorded systemic BP signal.15 While the optimization of BP is a major perioperative target there is no universally accepted guideline for defining hypotension. Furthermore, hypotensive episodes, are dynamic, not static phenomena and not only vary from patient to patient but also within a patient at different surgical stages. Therefore, measures of BP variability, quantified using different metrics, have been the focus of considerable interest. For example, in one study,16 BP variability was defined as the time spent above or below a target systolic blood pressure range of 95–135 mm of Hg, and an increased BP variability value was associated with higher 30-day mortality. In another study, BP variability was defined as the root mean successive square difference of a moving 5 second time period. In this investigation17, decreased intracranial pressure and BP variability were shown to predict long-term adverse outcome after aneurysmal subarachnoid hemorrhage. An intuitive limitation of traditional measures of variability is the fact that they do not take into consideration the temporal structure of a sequence of measurements. For example, the following two sequences: A = {1 2 3 2 1 2 3 2 1 2 3 2 1} and B ={1111222222333}16, have the same variability, as measured by amplitude of range and standard deviation, but completely different structures. In fact, while sequence A defines a triangular wave, sequence B is a step function. Measures that are sensitive to the temporal organization of a signal have been essential in characterizing and discriminating different dynamical systems. Here we assess BP fluctuation (variability) dynamics via two complementary metrics: 1) traditional standard deviation of BP time series and 2) the degree of complexity of their dynamics. The motivating framework for quantifying the degree of complexity of nonlinear physiologic signals, such as BP, is that complexity reflects the degree of robustness/resilience of the underlying control mechanisms, and it decreases with aging and pathology (http://physionet.org/tutorials/cv/, accessed Oct 21, 2013). The term nonlinear may be unfamiliar to readers of physiologic and clinical journals. Linear systems exhibit two properties: proportionality and superposition. Proportionality, as implied by the term, means that there is a straight-line relationship between input and output. Superposition indicates that one can completely understand the system (e.g., a Rube Goldberg-type device) by breaking it down into multiple sub-components. In contrast, the sub-components of a non-linear system do not “add up” to the whole because of either “constructive” or “destructive” interactions between those sub-components. In these cases, reductionist strategies will fail to provide full understanding of a given system.18,19 Furthermore, in nonlinear systems, unanticipated (“off-target”) effects are likely since small input changes may induce major changes in the output (the “so-called “butterfly effect”). Pilot Study: Overview In this pilot study, we tested the feasibility of: i) acquiring BP waveform data of sufficient length and quality for nonlinear complexity analyses, and ii) converting the data from a proprietary to an open-source format. Our specific hypothesis is that the complexity of the dynamics of systolic arterial (SAP), diastolic arterial (DAP) and pulse pressure (PP) from the post-bypass period is lower for the group of patients with MAEs (cases) than for a control group with comparable risk but no MAEs. We included pulse pressure dynamics in light of evidence that abnormalities in pulse pressure has been independently associated with up to 3-fold increase in MAEs following cardiac surgery.20

BACKGROUND: In the setting of protocolized glycemic control, the relationship between postoperative glycemic variability on major adverse events (MAEs) after cardiac surgery is unknown for patients with increased preoperative hemoglobin A1C (HbA1C >6.5%). In this study, we sought to establish (a) whether postoperative glycemic variability is associated with MAEs after CABG surgery and (b) whether preoperative HbA1C could identify patients at increased risk of postoperative glycemic variability. METHODS: Patients undergoing coronary artery bypass grafting with or without valvular surgery from January 2008 to May 2011 were enrolled in this prospective, single-center, observational cohort study. Demographic, intraoperative, and postoperative outcome data were obtained from institutional data collected for the Society of Thoracic Surgery (STS) database. The primary outcome, MAE was a composite of in-hospital death, myocardial infarction (MI), reoperations, sternal infection, cardiac tamponade, pneumonia, stroke, or renal failure. Glycemic variability in the postoperative period was assessed by the coefficient of variation (CV). CV was used as quartiles for the multivariate logistic regression. Variable selection in multivariable modeling was based on clinical and statistical significance and was performed in a hierarchical fashion. RESULTS: Of the 1461 patients enrolled, 9.8% had an MAE. Based on the established target of HbA1C <6.5% for the diagnosis of diabetes mellitus, we considered HbA1C as a binary variable (<6.5% and ≥6.5%) in our primary analysis. Multivariate logistic regression analyses for the preoperative variables only revealed that preoperative HbA1C (odds ratio [OR], 1.6; 95% confidence interval [CI], 1.1–2.3; P = 0.02), history of MI (OR, 1.9; 95% CI, 1.3–2.8; P = 0.001), and STS risk score per quartile (OR, 1.7; 95% CI, 1.4–2.1; P < 0.001) were associated with MAEs. When postoperative variables were included in the analyses, postoperative glycemic variability (CV per quartile) in the intensive care unit (OR, 1.3; 95% CI, 1.1–1.5; P = 0.03), mean glucose levels averaged over the first 4 postoperative hours (OR, 1.2; 95% CI, 1.0–1.4; P = 0.03), history of MI (OR, 1.8; 95% CI, 1.2–2.6; P = 0.004), and STS risk score per quartile (OR, 1.6; 95% CI, 1.3–2.0; P < 0.001) were associated with MAEs. Glycemic variability as assessed by CV was increased postoperatively in patients with preoperative HbA1C ≥6.5% (0.20 ± 0.09 vs 0.16 ± 0.07, P < 0.001). CONCLUSIONS: Postoperative glycemic variability is associated with MAEs after cardiac surgery. Glycemic variability is only measured when the patient leaves the intensive care unit, and there is no opportunity to intervene earlier. Preoperative HbA1C identifies risk for postoperative glycemic variability and may provide a more rational guide for targeting measures to reduce variability.

We propose that complex (nonlinear) fluctuations of hemodynamic variables (including systemic blood pressure parameters) during cardiovascular surgery contain information relevant to risk assessment and intraoperative management. Preliminary analysis of a pilot study supports the feasibility and potential merits of performing a larger, prospective study to assess the clinical utility of such new dynamical measures and to evaluate their potential role in enhancing contemporary approaches to risk assessment of major adverse events.

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.

We read with interest and concern the case scenario by Ahn et al.1 describing the use of the thromboelastograph to guide thoracic epidural placement in an elderly patient with chest trauma taking clopidogrel and aspirin. Despite presumed platelet inhibition, this patient’s thromboelastograph demonstrated a slightly hypercoagulable state with an increased maximum amplitude of 76.1 mm. We agree that trauma-induced inflammation and acute-phase reaction are possible causes of the reported thromboelastograph findings in this patient. However, we are concerned about the authors’ use of standard, kaolin-activated thromboelastography as a method to assess platelet function in the setting of a P2Y12 antagonist as well as aspirin.Thrombin is, by far and away, the most potent activator of platelets.2 This activation is accomplished through thrombin-mediated cleavage of the protease-activated receptors. Adenosine diphosphate, in contrast, is a relatively weak activator of platelets.3 Adenosine diphosphate agonism of the P2Y12 receptor serves to amplify the platelet in response to thrombin and to stabilize platelet aggregates. This results in a critical issue that practitioners using the thromboelastograph to guide interventions need to understand; kaolin-activated coagulation generates thrombin in quantities that are sufficient to overcome the effects of P2Y12 antagonists on platelet function as assessed by thromboelastography.4 In a similar manner, platelet inhibition by aspirin is also masked in kaolin-activated thromboelastography.Platelet inhibition can be assessed by a modified thromboelastograph assay known as TEG Platelet Mapping® (Haemonetics, Niles, IL). The details related to this assay can be found elsewhere. Despite the fact that authors’ discussion correctly identifies the need for this modified thromboelastograph assay to assess platelet inhibition from clopidogrel and aspirin, the assay was not used in the presented case. Instead, a supranormal maximum amplitude result from a standard thromboelastograph assay was incorrectly interpreted as representing a safe environment for neuraxial intervention.Fortunately, the patient described in this scenario did not appear to suffer any consequence. As the authors themselves note, several studies have found the risk of epidural hematoma to be extraordinarily low even in patients taking clopidogrel on the day of placement. Despite this, we strongly discourage the use of results from standard, kaolin-activated thromboelastography as evidence of a safe hemostatic milieu for neuraxial anesthesia or analgesia in a patient receiving any P2Y12 antagonist. Instead, we recommend using TEG Platelet Mapping® or another assay capable of assessing platelet inhibition from these medications.

Chapter 9 contains 87 questions and answers regarding cardiac anesthesia.

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.

BACKGROUND:Low tidal volumes have been associated with improved outcomes in patients with established acute lung injury. The role of low tidal volume ventilation in patients without lung injury is still unresolved. We hypothesized that such a strategy in patients undergoing elective surgery would reduce ventilator-associated lung injury and that this improvement would lead to a shortened time to extubationMETHODS:A single-center randomized controlled trial was undertaken in 149 patients undergoing elective cardiac surgery. Ventilation with 6 versus 10 ml/kg tidal volume was compared. Ventilator settings were applied immediately after anesthesia induction and continued throughout surgery and the subsequent intensive care unit stay. The primary endpoint of the study was time to extubation. Secondary endpoints included the proportion of patients extubated at 6 h and indices of lung mechanics and gas exchange as well as patient clinical outcomes.RESULTS:Median ventilation time was not significantly different in the low tidal volume group; a median (interquartile range) of 450 (264-1,044) min was achieved compared with 643 (417-1,032) min in the control group (P = 0.10). However, a higher proportion of patients in the low tidal volume group was free of any ventilation at 6 h: 37.3% compared with 20.3% in the control group (P = 0.02). In addition, fewer patients in the low tidal volume group required reintubation (1.3 vs. 9.5%; P = 0.03).CONCLUSIONS:Although reduction of tidal volume in mechanically ventilated patients undergoing elective cardiac surgery did not significantly shorten time to extubation, several improvements were observed in secondary outcomes. When these data are combined with a lack of observed complications, a strategy of reduced tidal volume could still be beneficial in this patient population.

Endovascular aortic surgery presents unique challenges to the anesthesia care team. The ability to care for potentially complex vascular problems in patients with a wide range of comorbidities through a relatively noninvasive, percutaneous approach allows for a seemingly endless number of permutations of anesthetic interventions. This can allow for what might be thought of as “interesting” combinations of interventions such as the placement of invasive arterial catheters at multiple sites and/or pulmonary artery catheterization in a patient ­undergoing a procedure under monitored anesthesia care (MAC) with little or no sedation. Furthermore, while the hope is always for a quick and complication-free operative course, the anesthesia care team must be prepared for potential catastrophe given the nature and location of the inherent pathology.