Seminars in Cardiothoracic and Vascular Anesthesia recent issues

Introduction

Nuttall, G. A., Schears, G. J. — 2009-09-18

Update on Safety Equipment for Extracorporeal Life Support (ECLS) Circuits

Riley, J. B., Scott, P. D., Schears, G. J. — 2009-09-18

Though much has been surveyed and written about the equipment aspects of extracorporeal life support (ECLS) in the past 10 years, there is value in reviewing the use and nonuse of multiple safety devices and techniques. Minimally equipped ECLS circuits for adult and pediatric bridge to decision during cardiac and respiratory failure are rapidly gaining popularity to maintain simplicity and portability. ECLS circuits employed for long-term therapy are outfitted differently and should include more safety devices. The purpose of this review is to compare and contrast the spectrum of minimally equipped ECLS circuits to circuits with maximum flexibility and safety device protection. Due to the lack of high-level, well-controlled scientific studies regarding ECLS equipment and safety devices, this study reviews the basis for how we use ECLS circuits and devices in our institution to provide safe patient support.

Optimal Time for Initiating Extracorporeal Membrane Oxygenation

Haile, D. T., Schears, G. J. — 2009-09-18

The technical evolution of extracorporeal membrane oxygenation (ECMO) coincides with the vast improvement in intensive care medicine of the past 4 decades. Extracorporeal circulatory technology substitutes for acutely failed cardiac or pulmonary function until these organs regain sustainable function through goal-oriented intensive care practice. The technology has been validated to improve survival in select patients who would otherwise have 100% mortality. This is by far the most complex life-sustaining technology employed and thus can contribute significant risks such that the decision to institute ECMO requires prompt risk and benefit analysis. Delaying the institution of ECMO may cause irreversible pulmonary and cardiac injuries in addition to other organs. Therefore, the optimal time of initiating ECMO support is crucial to the survival of a critically ill patient.

Anticoagulation and Coagulation Management for ECMO

Oliver, W. C. — 2009-09-18

Advances in extracorporeal membrane oxygenation (ECMO) management have helped to reduce complications compared with its inception but they remain high. The principal causes of mortality and morbidity are bleeding and thrombosis. The nonbiologic surface of an extracorporeal circuit provokes a massive inflammatory response leading to consumption and activation of procoagulant and anticoagulant components. The vast differences in neonatal and adult anticoagulation and transfusion requirements demands tremendous clinical knowledge to provide the best care. Increased use of thrombelastogram will complement other methods currently being used to improved care. Methods to recognize the level of thrombin formation at the bedside could help reduce neurologic complications. ECMO requires a multidisciplinary team approach to achieve the best outcomes.

ECMO Cannulation Controversies and Complications

2009-09-18

Advances in extracorporeal life support have expanded indications for use extending beyond patients undergoing cardiac surgery. The approach to cannulation in patients requiring extracorporeal membrane oxygenation should be individualized and based on the specific clinical scenario in which the need arises. Adherence to proper techniques of vessel visualization, exposure, and cannulation along with accurate placement of cannulae will optimize flows and minimize complications in this setting. Patients in need of mechanical circulatory support require input from a multidisciplinary team approach with systematic clinical evaluation to optimize outcome. If hemodynamics do not initially permit the successful separation from mechanical support, then a systematic search for potentially reversible patient and/ or pump related factors should be undertaken. The success of this therapy is predicated on patient selection, a multidisciplinary team approach in the intensive care unit, adherence to precise technical principles, and repeated patient evaluation.

Extracorporeal Life Support: Utilization, Cost, Controversy, and Ethics of Trying to Save Lives

Crow, S., Fischer, A. C., Schears, R. M. — 2009-09-18

Since the first successful application of extracorporeal membrane oxygenation (ECMO) in 1972, ECMO’s role in the management of respiratory and circulatory collapse continues to be refined and debated. Randomized clinical trials aimed at establishing efficacy and patient selection criteria have been fraught with ethical challenges. Growing concerns over rising health care costs require that careful evaluations of cost, utilization, and ethical issues surrounding heroic life-saving interventions such as ECMO are undertaken. Continued analyses of ECMO’s place in the medical management of respiratory and circulatory failure will help ensure that ECMO is used for not only prolonging life but also for providing a chance for "quality of life" following recovery from near-fatal illnesses.

Extracorporeal Membrane Oxygenation for the Treatment of Neonatal Respiratory Failure

Carey, W. A., Colby, C. E. — 2009-09-18

This review discusses the use of extracorporeal membrane oxygenation (ECMO) for the treatment of respiratory failure in neonates. After briefly reviewing the early history of neonatal ECMO, the authors describe the respiratory diagnoses most often treated with ECMO and the manner in which affected neonates are deemed to have "failed" conventional therapies and thus require ECMO. After reviewing the most common indications for ECMO, factors that influence the timing of conversion to extracorporeal life support, as well as criteria that may exclude patients from receiving ECMO therapy, are described. At the conclusion of this article, the authors discuss the long-term outcomes of neonates whose respiratory disease was treated with ECMO and the costs associated with that care.

Introduction

Murkin, J. M. — 2009-07-20

What Was Hot and What Was Not in 2007?: A Literature Review

Bainbridge, D. — 2009-07-20

While the number of publications each year in cardiac anesthesia is enormous there are a select group of interesting articles highlighting controversies in current practice or new techniques, medications, procedures which may change practice down the road. The purpose of this article is to review some of these articles. While by no means a systematic review, this article highlights some of the more interesting papers from the cardiac anesthesia and surgical literature from 2007. The articles focus on areas such as: methods to reduce both cerebral dysfunction and renal dysfunction, myocardial protection inhaled volatile anesthetic agents, and methods to reduce atrial fibrillation.

Mathematical Modeling in Cardiac Surgery: Helping Clinical Trials Answer the Question

Poullis, M., Poole, R. — 2009-07-20

Mathematical modeling, based on fundamental principles from engineering may help clinical trial design, aiding in answering problems that remain in cardiac surgery, such as management of carotid artery stenosis in patients undergoing cardiopulmonary bypass (CPB), hematocrit during CPB, adequacy of oxygen delivery during CPB, adequacy of blood pressure management during CPB, filtration during bypass for renal failure, bypass circuit pacification, carbon dioxide wound insufflation and neurological events, and pulsatile to nonpulsatile flow during CPB. In addition, mathematical modeling may help explain deficiencies of previous work that have failed to clarify what to do.

Redefining the Systemic Inflammatory Response

Landis, R. C. — 2009-07-20

From the first description of the "systemic inflammatory response" in the early 1990s, it has been recognized that this is a multifaceted response of the body to the combined insult of cardiothoracic surgery with bypass, involving causation by "activation of complement, coagulation, fibrinolytic, and kallikrein cascades, activation of neutrophils with degranulation and protease enzyme release, oxygen radical production, and the synthesis of various cytokines from mononuclear cells." Yet the intervening 15 years have seen a narrowing of research into individual systems and interventions naively targeted at single pathways without achieving clinically meaningful benefits. The time has come to redefine the systemic inflammatory response so that research can be more productively focused on objectively measuring and interdicting this multisystem disorder. A key concept of this new understanding is that translation into a hard adverse event occurs when the systemic imbalance is combined with a localized trigger. Triggers might be inadvertently provided by transient episodes of ischemia/malperfusion to vulnerable organs or handling trauma to major vessels. Future research should be directed at suppressing systemic activation with combinations of drugs and improved circuit coating, whereas changes in clinical practice and continuous monitoring of perfusion parameters can help eliminate localized triggering events.

Immediate Postoperative Care of the Heart Transplant Recipient: Perils and Triumphs

Novick, R. J. — 2009-07-20

The early postoperative care of a heart transplant recipient remains challenging, even in experienced centers with a long tradition of excellence. Approximately 10% to 20% of heart transplant recipients experience potentially life-threatening right ventricular dysfunction intraoperatively and early postoperatively due to an elevated pulmonary vascular resistance. In addition, heart transplant recipients experience a high risk of perioperative hemorrhage, as well as opportunistic infection and rejection. The authors describe a case of severe right ventricular dysfunction in a 46-year-old male several hours after heart transplantation for a dilated cardiomyopathy. This patient was salvaged by judicious multimodality therapy including the use of adrenergic agents, phosphodiesterase inhibitors, inhaled nitric oxide, and extracorporeal membrane oxygenation. The risk factors for the development of early graft failure after heart transplantation are reviewed, along with the principles of appropriate management of this complication.

Autonomic Nervous System and Cardiovascular Disease

Deschamps, A., Denault, A. — 2009-07-20

Because anesthesia affects the integrity of the autonomic nervous system, anesthesiologists use vital signs to maintain respiratory and circulatory homeostasis. However, patients with genetic predispositions or with autonomic dysfunctions are at risk of severe complications from anesthesia. For these patients, the monitoring of vital signs may not give sufficient warning to avoid complications. The development of methods to measure autonomic tone could be of interest to anesthesiologists because they could warn of changes in autonomic tone before vital signs are affected. New noninvasive methods are being developed to obtain measurements of parasympathetic and sympathetic output allowing for the monitoring of perioperative autonomic tone. These measurements are based on analysis of heart rate and blood pressure variability. In this report, the principals of the analysis of heart rate and blood pressure variability will be explained and the usefulness of these methods to anesthesiologists will be discussed.

Endovascular Treatment of Blunt Traumatic Thoracic Aortic Injury

Nicolaou, G. — 2009-07-20

Blunt traumatic thoracic aortic injury (BTTAI) is a lethal injury associated with a prehospital mortality of 80% to 90%. Patients arriving in the emergency room and considered appropriate to undergo emergency open surgical repair still have a mortality rate of 15% to 30% because of severe associated injuries. Conventional open surgical repair requires a left thoracotomy, single lung ventilation, aortic-cross clamping and unclamping, with or without the adjunct use of partial or full cardiopulmonary bypass and systemic heparinization. All this leads to significant physiological stress and surgical trauma resulting in perioperative complications such as major blood loss, coagulopathy, myocardial infarction, stroke, respiratory failure, renal failure, bowel infarction, and paraplegia. Despite advances in anesthesia, critical care medicine, and surgical techniques, a recent meta-analysis showed no definite improvement in operative mortality over the past decade, following open surgical repair in patients with BTTAI. Endovascular repair of BTTAI does not require a thoracotomy, single lung ventilation, aorticcross clamping and unclamping, or systemic heparinization. As a result, endovascular repair of BTTAI has emerged as an effective, minimally invasive treatment alternative, especially in patients with severe concomitant injuries, which may be prohibitive to open surgical repair. Recent published studies have shown that endovascular repair of BTTAI is associated with lower morbidity, mortality, stroke, and paraplegia/paraparesis rates, when compared with open surgical repair of BTTAI.

Optimal Versus Suboptimal Perfusion During Cardiopulmonary Bypass and the Inflammatory Response

De Somer, F. — 2009-07-20

Despite major improvements in perfusion techniques over the past 50 years, it is still not possible to formulate a clear definition of what is meant by optimal perfusion. In part this is due to the lack of sufficient evidence-based data and in part because of the complex pathophysiology that takes place during cardiac surgery with cardiopulmonary bypass. To find an answer we need to understand the exact mechanism of the inflammatory reaction triggered by the cardiopulmonary bypass. However, it is clear that further improvement of the cardiopulmonary bypass components alone will be sufficient. Only a combined strategy can further improve cardiopulmonary bypass—related morbidity and mortality. Such a combined strategy will embrace perfusion techniques as well as a pharmacological approach. It will also require a continuous monitoring of the microcirculation. The latter will not only allow to rapidly sense changes in the quality of perfusion but, even more important, also make it possible to intervene at the moment of deterioration. Recent research shows that such an approach has positive an impact on cardiopulmonary bypass—related morbidity postoperatively.

State-of-the-Art Blood Management in Cardiac Surgery

Samolyk, K. A. — 2009-07-20

Blood has been described as the most precious and personal substance in the world. Current directions in cardiac surgery are moving away from transfusing donor "Allogeneic" blood products, and towards improving methods of saving and preserving the patient's own "autologous" blood. Nothing else comes close to the natural healing abilities and homeostasis that one's own whole blood offers. No substitute, whether it is human or artificial, will ever work as well with fluid shifts, hemostasis and homeostasis. News reports today commonly feature severe blood shortages and research documenting recognized transfusion risks such as how older stored blood can put heart surgery patients at increased risk and others that point to the morbidity and mortality associated with its use. Therefore the medical community is moving towards more effective blood utilization by minimizing the exposure to donated blood. Current techniques are saving as much as possible of the patient's own blood that might otherwise be mismanaged or lost during surgery. Techniques, such as Ultrafiltration, that quickly concentrate and reinfuse whole blood back to the patient are the best choice. Admission to discharge hemovigilance requires a concerted multidisciplinary team effort with multimodal tools available in the coagulation armamentarium to effectively avoid this form of organ transplant. Improving outcomes and reducing morbidity and mortality in cardiac surgery takes place at the microcirculatory capillary level and with control of Hemostasis. Cardiac teams need to effectively communicate and minimize blood loss and hemodilution and reverse it, for state of the art blood management in Cardiac surgery.

Suction, Salvage, Sutures, and Potions: Blood Management Post-Aprotinin

Baker, R. A. — 2009-07-20

Hemostasis management of the cardiac surgical patient has changed following the withdrawal of aprotinin for use in cardiac surgical patients. The challenge to minimize blood loss and reduce exposure of cardiac surgical patients to blood products continues to grow with patients presenting being older and sicker and more complex procedures being performed. The cardiac surgery team has many options available for it to consider; although current recommendations strongly support the use of cell salvage as one process to assist in this challenge, other options need to be equally critically evaluated.

Lessons Learned in Antifibrinolytic Therapy: The BART Trial

Murkin, J. M. — 2009-07-20

Despite nearly 2 decades of published reports and clinical trials demonstrating the relative safety and efficacy of aprotinin in adult cardiac surgical patients at increased risk of bleeding—culminating in an official endorsement of the usage of aprotinin in such patients from both cardiac surgery and anesthesiology subspecialty committees—several more recent studies have raised profound concerns regarding the safety of aprotinin in these same patients. These studies and the implications thereof have ultimately resulted in the withdrawal of aprotinin from clinical usage internationally. This article will briefly review these developments with the hope of understanding how this abrupt turnabout took place and will attempt to understand how such events can be avoided in the future.

Physiology and Pharmacology of Myocardial Preconditioning and Postconditioning

Huffmyer, J., Raphael, J. — 2009-04-20

Perioperative myocardial ischemia and infarction are not only major sources of morbidity and mortality in patients undergoing surgery but also important causes of prolonged hospital stay and resource utilization. Ischemic and pharmacological preconditioning and postconditioning have been known for more than 2 decades to provide protection against myocardial ischemia and reperfusion and limit myocardial infarct size in many experimental animal models, as well as in clinical studies. This article reviews the physiology and pharmacology of ischemic and drug-induced preconditioning and postconditioning of the myocardium with special emphasis on the mechanisms by which volatile anesthetics provide myocardial protection. Insights gained from animal and clinical studies are reviewed and recommendations given for the use of perioperative anesthetics and medications.

Improving the Outcome of In-Hospital Cardiac Arrest: The Importance of Being EARNEST

Dichtwald, S., Matot, I., Einav, S. — 2009-04-20

Cardiopulmonary resuscitation techniques were introduced more than 50 years ago, yet the rate of survival from cardiac arrest, particularly in the hospital setting, remains dismally low. This article reviews the prevalence, etiology, and outcome of in-hospital cardiac arrest, with a focus on the determinants of outcome that are amenable to improvement. These include principally components of basic life support that may be supported by either prompting or mechanical assistance (eg, chest compression, ventilation, and defibrillation). Also reviewed are preevent and postevent effectors such as medical staff skills and recognition of impending arrest, induction of mild hypothermia, and stabilization after return of spontaneous circulation.

Current Perioperative Management of the Patient With a Cardiac Rhythm Management Device

Stone, M. E., Apinis, A. — 2009-04-20

The safe and effective perioperative management of the patient with a cardiac rhythm management device (ie, pacemaker and/or implantable cardioverter defibrillator) is based entirely on the avoidance of adverse outcomes, including damage to the device, the leads, or the site of lead implantation that might prevent the device from functioning as intended. An important management principle is the potential reprogramming of such a device in the perioperative period to avoid transient interruption of device function or the delivery of inappropriate electrophysiological therapy (eg, unnecessary defibrillation or pacing). Given the large numbers of patients worldwide currently implanted with these devices, the anesthesia practitioner should become electively familiar with the current technology. This article describes the current status of cardiac rhythm management devices and discusses recommended perioperative management.

Noninvasive Cardiac Output Determination: Broadening the Applicability of Hemodynamic Monitoring

Compton, F., Schafer, J.-H. — 2009-04-20

Although cardiac output (CO) monitoring is usually only used in intensive care units (ICUs) and operating rooms, there is increasing evidence that CO should be determined and optimized as early as possible, even before admission to the ICU, in the care of hemodynamically compromised patients. A variety of different minimally or noninvasive CO determination techniques have been developed, but not all of them are suitable for early hemodynamic monitoring outside the ICU. In this review, the different available methods for CO monitoring are presented and their potential for early hemodynamic assessment is discussed.

Cerebral Air Embolism Recognized by Cerebral Oximetry

Fischer, G. W., Stone, M. E. — 2009-04-20

Absolute cerebral oximetry is useful in clinical settings to identify "catastrophic events" that may occur during the course of surgeries that would otherwise have gone unrecognized. This study reports a case in which cerebral desaturation occurred after commencing cardiopulmonary bypass. Consequently, the source of air entrainment was discovered and therapeutic measures implemented.

Pulmonary Manifestations of Liver Diseases

Yeshua, H., Blendis, L. M., Oren, R. — 2009-04-20

Respiratory problems are common in patients with chronic liver diseases. The most common causes are disorders that are not related to liver diseases such as asthma and COPD. In addition certain liver diseases that are associated with specific pulmonary abnormalities, and conditions associated with end stage liver disease like tense ascites and intercostal muscular wasting are considered. Finally two unique disorders characterizing by vascular abnormalities independent of cardiorespiratory disorder-the hepatopulmonary syndrome (HPS) and portopulmonary hypertension (POPH) are observed. These disorders have different pathogenesis, different clinical pictures, treatment and prognosis. This article reviews the epidemiology, pathophysiology, clinical features, evaluation and current therapy of these two disorders.

Thinking From Inside the Box

Swaminathan, M. — 2008-12-23

New Echocardiographic Techniques for Evaluating Left Ventricular Myocardial Function

Marcucci, C., Lauer, R., Mahajan, A. — 2008-12-23

Ultrasound imaging of the heart continues to play an important role in diagnosis and management of patients with cardiovascular diseases. Recent advances in ultrasound technology and introduction of newer imaging modalities have enabled improved assessment of left ventricular myocardial function. Tissue Doppler imaging and 2-dimensional speckle tracking allow more objective quantification of myocardial function in the form of tissue velocities, displacement, strain, and strain rate. Similarly, contrast-enhanced echocardiography and 3-dimensional echocardiography have provided a unique insight into left ventricular form and function that was not possible by unenhanced 2-dimensional echocardiography. In this review, the authors discuss the clinical application of these new imaging techniques in the assessment of left ventricular myocardial function.

Real-Time 3-Dimensional Echocardiography in the Operating Room

Jungwirth, B., Mackensen, G. B. — 2008-12-23

Real-time 3-dimensional transesophageal echocardiography (RT-3D-TEE) represents a novel clinical and intuitively educational perioperative cardiovascular imaging modality. The development of RT-3D-TEE allows for live 3D imaging as it circumvents most of the disadvantages of reconstructive 3D methods. RT-3D-TEE will likely revolutionize perioperative assessment of complex 3D structures, such as the mitral valve (MV), as it provides important mechanistic insights into functional and ischemic mitral regurgitation. The MV is particularly suited to live RT-3D-TEE assessment because of the complex interrelationships among the valve, chordae, papillary muscles, and myocardial walls. The 3D en face view of the MV is in accordance with the surgical view and allows to illustrate the unique saddle shape of the MV annulus and to define and localize mitral leaflet lesions in MV prolapse, endocarditis, or congenital MV abnormalities, all potentially important in guiding surgical repair. RT-3D-TEE will soon be integrated into routine perioperative practice. Its unique ability of real-time acquisition, online rendering and cropping capabilities, accurate identification of the precise pathology and location of cardiac disease, together with its ability to promptly quantify 3D data sets using built-in software, will likely help in transitioning this modality into standard of care.

Transesophageal Echocardiography and Noncardiac Surgery

Mahmood, F., Christie, A., Matyal, R. — 2008-12-23

The use of transesophageal echocardiography (TEE) for monitoring during cardiac and noncardiac surgery has increased exponentially over the past few decades. TEE has evolved from a diagnostic tool to a monitoring device and a procedural adjunct. The close proximity of the TEE transducer to the heart generates high-quality images of the intracardiac structures and their spatial orientation. The use of TEE in noncardiac and critical care settings is not well studied, and the evidence of the benefits of its use in these settings is lacking. Despite the widespread availability of TEE equipment in US hospitals, less than 30% of anesthesiologists are formally trained in the use of perioperative TEE. In this review, the safety and indications of TEE are reviewed and detailed analysis of the best available evidence in this regard is presented. Landmark trials evaluating the use of TEE and its therapeutic impact in noncardiac surgical setting are critically reviewed. This article details recommendations to familiarize anesthesiologists with TEE technology to exploit it to its fullest potential to achieve better patient monitoring standards and eventually improve outcome. Training of greater numbers of anesthesiologists in TEE is needed to increase awareness of the indications and contraindications. Until relatively inexpensive TEE equipment is available, the initial cost of equipment acquisition remains a significant prohibitive factor limiting its widespread use.

An Argument for Routine Ultrasound Screening of the Thoracic Aorta in the Cardiac Surgery Population

Whitley, W. S., Glas, K. E. — 2008-12-23

Stroke and neurological injury are among the most devastating and disabling complications associated with cardiac surgery. Transesophageal echocardiography and epiaortic ultrasound allow for sensitive, point-of-care diagnosis of thoracic aortic disease, which is especially common in patients with heart disease. Unlike other operative procedures, the manipulation of the ascending aorta is routine in cardiac surgery and often unavoidable. Dislodgement and embolization from the ascending and aortic arch atheromas have been clearly associated with manipulation during cardiac surgery. Epiaortic ultrasound and transesophageal echocardiography screening are more accurate and more accessible to the operative team than any other available modality to diagnose atherosclerosis of the aorta. The goal of this review is to review the rationale and scientific evidence that suggests that the routine use of ultrasound guidance in cardiac surgery may improve postoperative outcomes in this patient population.

Endovascular Approaches to Complex Thoracic Aortic Disease

Hughes, G. C., Sulzer, C. F., McCann, R. L., Swaminathan, M. — 2008-12-23

Diseases of the thoracic aorta remain among the most lethal and difficult to treat conditions. In 2005, the US Food and Drug Administration approved the first endoprosthesis for the treatment of aneurysms of the descending thoracic aorta; at present, there are 3 thoracic devices approved by the US Food and Drug Administration. Although approved only for the treatment of descending aneurysms, thoracic endografting has other potential off-label applications, including acute and chronic aortic dissection and traumatic aortic transection. Endovascular repair of thoracic aortic pathology is emerging as the preferred treatment strategy in certain patients, as increasing data suggest that endovascular repair may be performed with lower peri-operative morbidity and mortality rates and similar midterm survival, when compared with standard open repair. However, because of anatomic constraints related to required endograft seal zones, a significant number of patients are excluded from standard endovascular repair. Hybrid techniques, including open aortic arch and thoracoabdominal debranching procedures, have been described to allow creation of proximal and/or distal landing zones for the stent graft seal. This review describes the surgical and anesthetic considerations relevant to thoracic endografting, with an emphasis on hybrid procedures used to treat more complex thoracic aortic pathology. Hybrid techniques may be performed with lower rates of morbidity and mortality than conventional open repair, and they appear to be a safe alternative to open repair for thoracoabdominal and aortic arch aneurysms in properly selected patients with significant comorbidity or prior open aortic surgery.

Emerging Concepts in Acute Kidney Injury Following Cardiac Surgery

2008-12-23

Acute kidney injury (AKI) remains a significant cause of morbidity and mortality following cardiac surgery. Through a more thorough understanding of perioperative genomics and the evolving role of early biomarkers ofAKI, the authors seek to improve meaningful outcomes among cardiac surgery patients. In this review, the focus will be on advances in risk stratification, evolving definitions and improving early diagnosis of AKI, identification of effective individualized therapies, and future directions.