Focused Transthoracic Echocardiography in Hip Fracture Surgery Patients

Despite advances in medical care, hip fracture surgery remains one of the commonest and highest risk surgical procedures (10% in-hospital mortality and 25% at one year), representing a major economic cost to our community and a World health care burden. Hip fracture patients are usually elderly and chronic cardiovascular disease is common. Due to urgency of surgery, frequent patient cognitive impairment and limitations in health care resources, cardiac disease is often inadequately treated and remains the leading cause of mortality. Preoperative transthoracic echocardiography (TTE) performed in the echocardiography laboratory non-invasively alerts treating physicians to cardiac disease but may result in a delay which is associated with worse outcome and hence is usually restricted to selected patients. Anesthesiologists have been increasingly performing their own ‘goal-focused TTE’, an abbreviated examination which really forms an extension of clinical examination, which also alerts the anesthesiologist to abnormal hemodynamic states such as hypovolemia, ventricular failure and vasodilation, thus guiding appropriate hemodynamic treatment and monitoring before, during and after surgery. Recent published data showed a major influence of goal-focused TTE on management of patients requiring hip fracture and other non-cardiac surgery. Further proof of concept data has revealed that mortality may be reduced in hip fracture surgery patients who receive a preoperative focused transthoracic echocardiography by the anesthesiologist. This technology has the potential to drastically improve the medical care of patients at high risk of cardiac disease requiring non-cardiac surgery. Recently, several guidelines from learned societies of echocardiography have been published on recommendations for training and practice of focused TTE by non-cardiologists for ultrasound assisted examination. Focused TTE requires significant training and funding and to justify this important and rapid shift in medical practice, there is a need for high quality outcome studies to be performed. Equally important are efficient teaching methods and a robust mechanism to ensure minimum standards of proficiency to minimize the recognised potential harm from erroneous conclusions drawn from misinterpretation of data. Central Canty et al. (2013) Email: [email protected] Int J Clin Anesthesiol 1(3): 1014 (2013) 2/8 including dementia, which inhibits accurate medical assessment. Careful cardiac assessment and treatment is often missed because surgery is urgent and there is time-pressure to proceed to surgery to palliate their pain and get them out of hospital. These patients often receive a lower priority in view of their advanced age and other considerations such as residence in a nursing home. They are often managed by junior doctors, who may not have the experience or confidence to adequately investigate and treat underlying cardiovascular disease prior to surgery. Can Better Treatment Reduce Mortality? Despite the enormity of the problem there are surprisingly few data on improving outcome in these patients in the anesthetic literature. There are several large audits of mortality in patients undergoing hip fracture surgery, reporting mortality rates from 5 to 25 % [16,17]. These audits do not present morbidity data. It is reasonable to estimate, however, that morbidity will be two to three times the incidence of mortality. Venn et al. [18] demonstrated an earlier hospital discharge in hip fracture surgery patients who had their fluid treatment managed with intraoperative esophageal Doppler compared with central venous pressure monitoring. Sinclair et al. [19] demonstrated faster recovery after hip fracture surgery utilizing esophageal Doppler-guided fluid management compared with standard fluid management, which should translate into reduced hospital length of stay and therefore reduced cost. Both studies were insufficiently powered to show a reduction in morbidity or mortality. At Cornell Medical Centre [10], a specialist orthopedic hospital, most fractured hip surgery patients are treated intensively (regional anesthesia, invasive monitoring, postoperative intensive care and rehabilitation) with a resulting much lower mortality rate (1.5% compared to the standard average of 10%) this highlights that lives can be saved in this at-risk population if they are given intensive treatment (and not treated as “second class patients”). How Could Preoperative Goal-Focused Transthoracic Echocardiography Make a Difference? Preoperative cardiac assessment, as recommended by the American and European Heart Associations [20,21], enables improved cardiac treatment and reduction of cardiac complications. However, despite a high incidence of cardiac disease [22] and dehydration in these patients [23], there is often reluctance to perform preoperative cardiac investigations such as echocardiography or to utilize intensive perioperative monitoring, due to the urgency of surgery and advanced patient age [24-28]. There have been several comprehensive guidelines published from multidisciplinary expert groups in recent years, and a common theme has been emphasis on minimizing delays to theatre, which is associated with worse outcome [29-31]. This has increased the pressure on anesthesiologists to ‘skip’ standard preoperative investigations, such as transthoracic echocardiography (TTE), to avoid an associated delay and perceived increase in poor patient outcome. This has been exacerbated in the UK with the introduction of the Best Practice Tariff (BPT) for hip fracture surgery in April 2010, which penalizes hospitals by withdrawal of funding of £1335 (€1706; $2102) [32] if there is a delay in surgery of over 36 hours from the time of diagnosis [33]. These recommendations have led to considerable resistance from orthopedic surgeons to delay surgery for TTE, whose current recommendations are to avoid delays to surgery beyond 48 hours [31]. However, preoperative TTE in these patients remains controversial as some authors favour a low threshold for for this useful and non-invasive investigation [27,28,32], principally to identify asymptomatic severe aortic stenosis, which is associated with a marked elevation in poor outcome [34-36]. One group reported success of a routine preoperative focused TTE program by cardiac sonographers, which identified undiagnosed significant (moderate or severe) aortic stenosis in 8% [27]. Other reported benefits of preoperative TTE include risk stratification enabling a higher level of intraoperative hemodynamic monitoring, postoperative care and analgesia [37]. Operative risk is likely to be reduced by surgical management. Apart from recommending a higher level of seniority of surgeon and anesthesiologist [30], uncemented prostheses have been suggested to prevent bone cement implantation syndrome in patients at high risk, including older patients with impaired cardiopulmonary function [38]. A preoperative TTE may identify patients who may benefit from this practice before arrival of the patient into the operating room. Good examples of patients who may benefit from preoperative TTE are those with aortic stenosis and hypovolemia. Severe aortic stenosis is associated with 4-10 fold increased mortality after non-cardiac surgery [34-36]. Aortic stenosis restricts the left ventricular stroke volume impairing the ability to cope with hemodynamic demands from anesthesia and surgery. If not appropriately managed, cardiac output may become irreversibly depressed and cardiac arrest may ensue. An example is spinal anesthesia, commonly used in hip fracture surgery, which may cause an uncontrollable decrease in systemic vascular resistance. Significant aortic stenosis was present in 8% of a large series of hip fracture surgery patients, but a detectable murmur was not found in one third [27]. Approximately 50% of patients with hip fracture have ejection systolic murmurs and 26-32% have some degree of aortic stenosis [39]. Confident diagnosis of aortic stenosis requires TTE which is associated with a delay in surgery and is often avoided resulting in the anesthesiologists managing the anesthesia and cardiac treatment based on “best guess” clinical assessment. This management approach is not ideal, as if severe aortic stenosis is presumed rather than proven, then patients without aortic stenosis may receive unnecessary invasive management (for example intra-arterial blood pressure and central venous pressure monitoring and postoperative intensive care). On the other hand, patients with severe aortic stenosis may not receive expensive postoperative high level care (from the orthopedic and geriatric medicine teams) as aortic stenosis was only ‘presumed’ by the anesthesiologist. With appropriate perioperative care patients should not die of this condition. However, inadequate treatment could result in hypotension, leading to organ failure and death. This is a preventable death. Approximately half of hip fracture patients who present for surgery are hypovolemic from bleeding, reduced oral intake, and a reluctance of medical staff to give fluids for fear causing pulmonary edema [23,40]. Hypovolemia and cardiac failure is Central Canty et al. (2013) Email: [email protected] Int J Clin Anesthesiol 1(3): 1014 (2013) 3/8 easily detectable with TTE enabling prompt and safe treatment prior to surgery. Unlike esophageal Doppler monitoring (as studied by Venn and Sinclair), TTE provides accurate intravascular volume assessment before surgery, allowing time for correction before anesthesia and surgery commences, which may help avoid hypotension and improve tissue perfusion. Additionally, TTE may prompt avoidance of fluid therapy when cardiac failure is identified. Anesthesiologists assess all hip fracture surgery patients and optimize their cardiac treatment to cope with the stress of anesthesia and surgery. They are the principal physicians responsible for identifying high-risk patients, deciding whether to proceed or delay surgery and the level of intraoperative and postoperative cardiac treatment and monitoring that is required. Indicators of abnormal cardiovascular function are obtained by the anesthesiologist from the history (such as shortness of breath, chest pain, or hypertension), or from the examination (such as reduced blood pressure or increased heart rate; or evidence of poor tissue perfusion such as a cool periphery or reduced urine output). Additional hemodynamic monitoring (which is rarely used in these patients) can include central venous pressure, pulmonary artery pressure, or cardiac output. If abnormal, these parameters suggest that there is a cardiovascular disorder, but they do not indicate what the cause is. For example, a low blood pressure and increased heart rate could equally be caused by hypovolemia, heart failure, or severe aortic stenosis. The treatments and postoperative care required for these conditions are very different. Goal-focused TTE utilizes the same echocardiography techniques as conventional comprehensive outpatient echocardiography performed by cardiology. The difference is that it is brief and limited, and the practitioner performing the study uses it to answer specific clinical questions. In a more generic term, it can be considered “ultrasound assisted examination”. What the anesthesiologist needs to know to improve the safety of the procedure is: • Is there a significant abnormal hemodynamic state of the patient? (eg. hypovolemia, cardiac failure, vasodilation or normal) • Are there any heart valve abnormalities that could lead to hemodynamic instability? (eg. aortic or mitral stenosis) • Are there any additional incidental findings that could contribute to hemodynamic instability? (eg. severe pulmonary hypertension or a large pleural or pericardial effusion) Goal focused TTE is used as an extension of clinical examination of the primary treating physician at the patient’s bedside and is used to guide diagnosis and treatment in real time. This is a different approach to the traditional wait for a comprehensive TTE to be performed hours to days after referral. Unlike comprehensive TTE, focused TTE is performed quickly so as not to delay clinical management and is directed at qualitative assessment rather than detailed quantitative assessment. Thus differentiating hemodynamically significant disease, such as moderate to severe ventricular dysfunction, or valvular stenosis or regurgitation, from mild dysfunction which is unlikely to cause a hemodynamic problem during the stress of surgery and anesthesia. The focused TTE exam is directed at ventricular volume (direct assessment of preload), function, and the presence of other potential major causes of hemodynamic instability such as vasodilation, pericardial effusion and pulmonary hypertension. Due to limited training and time with which to perform the TTE, it is possible that cardiac pathology could be misinterpreted or missed. There exists a trade-off between comprehensive TTE which is used unlikely to miss pathology, but which is restricted in use to a selected few patients but unlikely to be used to guide immediate treatment, versus focused TTE which may miss pathology but provides useful hemodynamic information at the bedside when it is required, but is still much less likely to get the diagnosis wrong than clinical examination and may be used to benefit a much larger number of patients. Hemodynamic State and Consequences for Treatment The concept of hemodynamic state assessment is to categorize hemodynamic disturbance into seven broad conditions indicative of underlying disease [41]. This gives the anesthesiologist much better understanding of the cardiovascular disorder. Therapeutic strategies can then be better targeted to treat the underlying disorder early and proactively (such as fluid transfusion for hypovolemia) rather than simply reacting to hypotension during surgery. Transthoracic echocardiography is used to assess left ventricular volume, left ventricular systolic function, and estimate left atrial pressure [41]. The three components when put together provide a guide to the primary hemodynamic state (Table 1) and suggest the appropriate treatment (eg. fluids for hypovolemia, vasopressor for vasodilation). Importantly, hemodynamic state assessment using ultrasound can be obtained rapidly and from limited views. Hemodynamically Important Valve Lesions and Effusions Because of the advanced age of these patients, moderate to severe valve lesions are common and are frequently undiagnosed at the time of surgery. Severe aortic stenosis is a classic example of a valve lesion that can lead to death if not properly managed during the perioperative period. If diagnosed, anesthesiologists will step-up their level of care and adjust the anesthetic technique to maintain cardiovascular stability. This may involve the use of invasive monitoring, vasopressor agents, careful optimization of fluid therapy and postoperative analgesia and a decision to send the patient to a high dependency or intensive care environment after surgery, where closer hemodynamic monitoring and treatment is sustained. A warning to the surgeon of high patient cardiac risk may prompt more efficient surgery and less blood loss and consideration of less invasive techniques such as nocement. Preoperative goal focused TTE provides the treating anesthesiologists with a higher level of knowledge about the patient, upon which they can base more rational therapy. What Evidence is there that Preoperative GoalFocused TTE Makes a Difference? The core of the problem of preoperative TTE lies in the lack of resources available to provide prompt service in time before surgery. In most reports, preoperative TTE before hip fracture surgery was provided by cardiology or radiology Central Canty et al. (2013) Email: [email protected] Int J Clin Anesthesiol 1(3): 1014 (2013) 4/8 departments, who provide a comprehensive and thorough echocardiography examination but at the cost of an average delay to surgery of 3 days [25-27]. It has been suggested that perhaps anesthesiologists should learn to perform TTE to provide timely TTE in these patients [24]. Subsequently, there have been reported observational studies of anesthesiologistperformed preoperative ‘focused TTE’ demonstrating a major impact on anesthetic and surgical management, not only in hip fracture surgery patients but also before other emergency noncardiac surgery and in elective surgery patients presenting to the preoperative clinic (Table 2). In patients who have or are at risk of cardiac disease, clinically significant pathol ogy detected by preoperative focused TTE is in the order of 25% [42,43], which frequently leads to changes in perioperative management. In prospec tive observational studies by Canty et al. [42,44,45] and Cowie [43] on 456 surgical patients, a high degree of therapeutic impact from focused TTE was demonstrated (39% to 82%). The anesthetic management plan was compared before and after a focused TTE performed by an anesthesiologist not involved in care of the patient who was suitably proficient in focused TTE. In these studies, TTE was predominately performed before anesthesia (90%) for noncardiac surgery, but also during and after surgery in mechanically ventilated patients. The ability of useful information from TTE in mechanically ventilated patients, traditionally poor, is likely to reflect significant improvements in echocardiography technology. In the studies reported by Canty et al., although the highest impact on important management changes occurred after identification of significant cardiac pathology, thus declaring high cardiac risk patients and alteration in preoperative assessment and level of postoperative care (10%–15%), surgery was also changed for a small proportion of patients (2%) as a result of the new information from TTE. Most changes were in hemodynamic management (30%–40%), including more rational use of invasive monitoring and fluid and vaso pressor use. Canty et al. [42], reported that in a prospective study of goal-focused TTE used in the preoperative clinic, the overall effect was to step down planned treat ment (based on a reassurance from normal TTE findings) in more patients than to step up treatment based on clini cally significant pathology. This resulted in reduced intensity of preoperative, intraoperative and postoperative treatment and resource use. This, however, has not yet been subjected to economic or outcomes analysis. The overall finding of these studies is that clinical examination is unreliable, as it is proved incorrect approximately 50% of the time by TTE. In 2012, Canty et al. published the first and only existing report that suggests that echocardiography may result in improved postoperative survival [47]. In this retrospective analysis of two reported prospective observational studies [44,45], 64 patients from two centers were identified who received anesthesiologistperformed focused TTE before hip fracture surgery in patients who were deemed to be at increased cardiac risk by the treating anesthesiologist, but in whom had not received a preoperative TTE in the previous 12 months. The mortality over 12 months was compared to a randomised cohort with similar cardiac risk who did not receive preoperative TTE. This control group was generated by randomly selecting patients from the hospital surgical databases with ASA score greater than 2 and age greater than 60 years, and on subsequent analysis, the two groups (TTE Echo parameter Normal Empty Primary diastolic failure Systolic failure Systolic +diastolic failure Vasodilation Right Ventricular failure LV Volume N ↓ N ⁄↓ ↑ ↑ N RV↑ LV Systolic function N N/↑ N ↓ ↓ ↑ RV↓ LV Filling pressure N ↓ ↑ N ↑ N ↑ Table 1: Transthoracic echocardiography hemodynamic state classification [41]. LV is left ventricle, RV is right ventricle, and arrows are increased or decreased. Study Methodology Influence of TTE on management Comments Canty 2009 [44] 87 patients in whom TTE was requested by the treating anesthesiologist. Medical management changed in 34% (hemodynamic management, anesthetic technique and postoperative care) and surgical management in 7% (surgery altered in 2% and deferred in 5%). TTE performed by single anesthesiologist (HEART scan*). Changes occurred in the preoperative assessment clinic (9%), operating room: preoperative (25%), intraoperative (10%) and post anesthesia recovery unit (2%). Cowie 2011 [43] 170 patients. Indications for TTE included murmur (58%), hemodynamic instability, ventricular function, dyspnea, and poor functional capacity. Management changed in 82% including postponed surgery for cardiology TTE (20%), cancelled surgery (4%), perioperative hemodynamic changes (51%) and level of postoperative care (7%). TTE performed by multiple anesthesiologists. Significant aortic stenosis identified in 11%, pulmonary hypertension in 14%. Findings confirmed by a cardiologist in 92%. Canty 2012 [42] 100 patients seen in the preoperative assessment clinic. Indications included suspected cardiac disease or age>65 years. Management changed in 54% including changed surgery in 2%. Changes included a step-up in treatment in 36% and a step down in treatment in 8%. TTE performed by a single cardiac anesthesiologist (HEART scan*). Findings confirmed by a cardiologist in 92% . Canty 2012 [45] 99 emergency non-cardiac surgery patients. Indications included suspected cardiac disease or age≥ 65 years. New findings were found in 67% and management was changed in 44% including changed surgery in 2%. Changes included a step-up in treatment in 20% and a step down in treatment in 34%. TTE performed by multiple anesthesiologists (HEART scan). Procedural changes in 14% (preoperative referral, surgery type or level of postoperative care) and hemodynamic management changes in 30% (invasive monitoring, fluid and vasopressor and anesthetic technique). *HEART scan, Hemodynamic transthoracic Echocardiographic Assessment in Real Time (University of Melbourne)[46] Table 2: Summary of prospective observational studies on the impact of transthoracic echocardiography on decision-making and outcome in non-cardiac anesthesia. Central Canty et al. (2013) Email: [email protected] Int J Clin Anesthesiol 1(3): 1014 (2013) 5/8 and control) had very similar risk factors. Mortality was lower in the TTE group over the 30 days (4.7% v 15.2%, p=0.047) and 12 months after surgery (17.1% versus 33.3%, p=0.031). Hazard of death over 12 months was reduced after adjustment for known risk factors (hazard ratio 0.41, 95% CI 0.2 to 0.85, p=0.016). Thus mortality was halved in the patients who received preoperative focused TTE and this persisted to 12 months after surgery. Diagnosis and management were changed in the majority of the 64 hip fracture patients after goalfocused TTE (Figure 1). This provides a plausible mechanism of effect of the association in reduced mortality in patients who received preoperative focused TTE. The anesthesiologists were not only alerted to identification of patients with significant cardiac disease, the TTE also provided the hemodynamic state (eg. hypovolemia, ventricular failure or vasodilation) which assisted the anesthesiologist in more rational hemodynamic treatment. Because the TTE was performed before commencement of anesthesia, this enabled TTE-guided hemodynamic treatment to be commenced before the hemodynamic stress of anesthesia and surgery, perhaps reducing the degree of perioperative hemodynamic compromise that is so common in these patients. Furthermore, as the hemodynamic and cardiac status were defined before anesthesia, the anesthesiologist is likely to have been better prepared for management of any subsequent hemodynamic instability. TTE identified significant disease in a third of patients where clinical assessment had indicated that there was no cardiac disease present, highlighting not only the inaccuracy of clinical examination but the high incidence of occult cardiac disease in this elderly population. Unlike previous reports [25-27], there was no delay before surgery associated with performance of preoperative TTE (1.7±1.9 mean days before surgery) compared with patients who did not receive preoperative TTE (1.4±1.2 days, p=0.41). Due to the retrospective nature of this study the findings of this study need to be considered as proof of concept only but it represents strong pilot data that supports a large prospective randomised controlled trial. Focused echocardiography is more accurate than clinical examination alone [48-50] and this could explain the difference in short-term mortality by correct diagnosis of life-threatening cardiac pathology, leading to changes in peri-operative management. A possible reason for the persistent reduction in mortality at after 12 months is that detection of significant cardiac pathology using TTE may have led to better post-hospital management of cardiac disease, which may then have led to a further reduction in mortality. If patients survive surgery, but suffer cardiac failure in the peri-operative period [15], they then have a 92% mortality at 12 months, indicating that cardiovascular morbidity at the time of surgery is an important contributor to longer-term mortality. It is possible that preventing cardiovascular complications at the time of surgery may help reduce long-term mortality. Potential Harm of Focused TTE Transthoracic echocardiography is considered by many as non-invasive however, this term probably only applies to the physical effects of surface application of the probe to the patient, compared to of transesophageal echocardiography (TEE) which occasionally causes esophageal perforation with potentially serious consequences. Transesophageal echocardiography also requires sedation or general anesthesia with its associated morbidity including airway complications such as airway obstruction, respiratory failure and pulmonary aspiration of gastric contents. One of the principal risks of TEE identified by learned societies of echocardiography include misinterpretation of acquired data, which can result in Figure 1 Changes in diagnosis and management by the treating anesthesiologist after preoperative focused TTE in 64 hip fracture surgery patients combined from two