CCAS 2016 Annual Meeting Review
By Faith J. Ross, MD
Seattle Children’s Hospital
Viviane G. Nasr, MD
Boston Children’s Hospital
Morning Sessions
This year’s program director Mark Twite, MD, BCh (Colorado Children’s Hospital, Aurora) and co-directors Scott Walker, MD (Riley Hospital for Children, Indianapolis) and Luis Zabala, MD (Children’s Medical Center Dallas, Dallas) have put together an outstanding variety of topics and speakers covering high altitude and its relevance to the anesthesiologist, updates on anesthesia practices and adult congenital heart disease.
Session I: Basic Science and clinical application
Mark D. Twite, MD, BCh (Colorado Children’s Hospital, Aurora) introduced the first session of the day.
Andrew Lovering, PhD (University of Oregon, Oregon) started the session with a talk about patent foramen ovale (PFO), its effect on ventilation and core temperature at different altitude levels. The incidence of PFO ranges between 25% and 38% in the general population. The presence and size of the PFO play a role when assessing pulmonary gas exchange. The A-aDO2 increase is higher in patients with PFO during exercise. In addition, subjects with PFO have a blunted respiratory acclimatization and do not significantly increase resting ventilation at higher altitude and therefore arterial oxygen saturation decreases. PFO subjects have a higher core temperature. The combination of a lower PaO2 and increased core temperature lead to a right-shifted oxyhemoglobin dissociation curve and therefore lowering the oxygen arterial saturation. At high altitude, this will cause an exaggerated pulmonary hypertension and right ventricular dysfunction.
Hilary Grocott, MD (University of Manitoba, Manitoba, Canada) followed with a discussion about the importance of neurologic outcomes following cardiac surgery in children as these patients are living into adulthood. Incidence of neurologic injury in children is 40-50% ranging from stroke, intracerebral hemorrhage, white matter lesions, sub-clinical MRI lesions, functional and developmental abnormalities, and seizures. Neurologic insults can occur at multiple stages of life starting prenatally and continuing through the perioperative periods with preoperative, intraoperative and postoperative risk factors. Multiple strategies have been applied to optimize cerebral outcomes. Non-pharmacologic tools include temperature monitoring with avoidance of hyperthermia, pH-stat management, optimizing oxygen delivery, maintaining hematocrit >24%, avoidance of hypo-perfusion. There is no evidence yet for any beneficial pharmacologic therapy. Cerebral monitoring including BIS/EEG, temperature, cerebral perfusion pressure and cerebral oximetry are recommended.
The session concluded with an audience question showing that the majority of the attendees use regional cerebral perfusion whenever possible.
Questions
A comment by Dr Andropoulos (Texas Children’s Hospital, Texas) to Dr Grocott: Using high flow rates for 71 min RCP shows a seizure rate < 1% and decent neurodevelopmental outcomes suggesting the importance of high flows.
Comment to Dr. Lovering suggested a potential benefit of hypoventilation in subjects with PFO to decrease shunting and have a right shifted oxyhemoglobin dissociation curve so they can unload more at the tissue.
Question for Dr. Lovering: Were there differences in TCD and NIRS in pts with PFO?
Answer: This was not possible to see because the number of subjects per group was too small.
Question for Dr Lavering: What is the impact of PFO on elite athletes?
Answer: The team is planning to study that. It may be related to overheating in some athletes.
Session II: Practice Updates in Congenital Cardiac Anesthesia
Wanda Miller-Hance, MD (Texas Children’s Hospital, Houston) led an excellent discussion of practice updates in congenital cardiac anesthesia.
Susan Nicolson, MD (Children’s Hospital of Philadelphia, Philadelphia) began the session with an update on pediatric cardiac care improvement through collaborative learning. Although randomized controlled trials provide important data to guide clinical care, the utility of large trials is practically limited due to time, cost, and delay in dissemination of findings. An alternative strategy of collaborative learning provides a more timely and convenient method of standardizing and improving care. Pediatric cardiac surgery is ideally suited to this approach due to the high complexity, low volume at individual centers, and high resource utilization. Dr. Nicolson’s team chose duration of mechanical ventilation after repair of Tetralogy of Fallot and coarctation as the initial focus of this project.
Clinicians and engineers visited five benchmark pediatric cardiac surgery centers to determine if there were elements of outcome variation that could be modified by collaboration. The team conducted site visits and phone calls and developed a clinical practice guideline to be disseminated among the sites. Five additional sites served as controls during the period of intervention. After intervention, the investigators found that extubation within 6 hours increased from 13% to 73% at the active sites, but remained constant at around 10% in the control sites. They found no increase in the incidence of reintubation and a significant reduction in the duration of sedation and time to enteral feeding. ICU length of stay was similar. Compliance with the clinical practice guideline was 91%.
These promising results demonstrate that a multidisciplinary collaborative approach can reduce practice variation and improve outcomes. Important further steps include evaluation of sustainability of these changes, dissemination of clinical practice guidelines to other sites, and application of the collaborative process to other aspects of pediatric cardiac care.
Glyn “Jumbo” Williams, MB, ChB (Lucille Packard Children’s Hospital, Palo Alto) followed with an interesting presentation on blood factor concentrates. The development and availability of factor concentrates has raised important questions about the role of these products in reducing adverse effects associated with bleeding and transfusion.
Currently, these products are used off label in pediatric cardiac surgery and high quality data regarding safety and efficacy is limited. Types of factor concentrates available for clinical use include Prothrombin Complex Concentrates (PCCs), fibrinogen concentrate (FC), and activated Factor VII (FVIIa).
In vivo studies show efficacy of FVIIa as a rescue strategy in pediatric cardiac surgery with reduced bleeding, decreased need for blood products, and a high patient response rate. Patients with elevated INR, inadequate platelet count, diminished factor levels, or low pH are less likely to respond to FVIIa. Adverse events are more commonly related to severity of bleeding than the medication itself. Thrombotic events are observed in 12% of adults and 5% of children and are unrelated to dose. There appears to be no difference in safety between FVIIa and FEIBA (a type of PCC). Overall, FVIIa appears to be useful for rescue of serious bleeding in pediatric cardiac surgery. There is no data to support its use as a transfusion reduction strategy.
Fibrinogen is the first coagulation factor to decline during hemodilution and hemorrhage and is a crucial factor for clot formation and strength. Fibrinogen concentrate is commonly used as a rescue therapy in Europe in place of cryoprecipitate. As part of a transfusion reduction strategy, FC is equivalent to cryoprecipitate in terms of blood loss, transfusion requirement, and fibrinogen levels. Adult studies showed higher fibrinogen levels and a reduction in transfusion from 100% to 45% with FC vs. placebo in patients undergoing aortic surgery. In these studies, a fibrinogen level greater than 287 appeared to be associated with decreased clinical bleeding. FC is associated with a low incidence of allergic reaction and thromboembolism.
There are several types of PCCs, all of which contain factors II, IX, and X, but differ in inclusion of other factors including factor VII and protein C and S. Adult studies suggest that PCCs are more effective as a rescue therapy than FVIIa, but no pediatric data are available. Pediatric studies evaluating use of PCCs to reduce donor exposure indicate less bleeding and similar donor exposure vs. matched controls. In adults, 4-factor PCCs are associated with less thrombosis than FC and appear to be an effective alternative to fresh frozen plasma. PCCs increase thrombin potential for 3-4 days and can potentially lead to a dangerous prothrombotic state. Overall, PCCs appear to be superior to FVIIa as a rescue therapy with similar safety profile.
Dr. Williams wrapped up his presentation with a suggested algorithm for use of factor concentrates in severe bleeding:
- Use FC early after bypass, aiming for a goal fibrinogen around 300 mg/dL
- Assay platelet function to determine the need for platelet administration
- If bleeding continues, use PCC
- If bleeding persists despite PCC, use FVIIa
The session concluded with an outstanding discussion of heparin alternatives by Tony Moriarty, BCh (Birmingham Children’s Hospital, Birmingham, UK). Although heparin does have some well known disadvantages, there is no great alternative currently on the market. Alternatives to heparin may be indicated in heparin allergy, heparin-induced thrombocytopenia, or heparin resistance.
Heparin-induced thrombocytopenia (HIT) develops in 1-4% of patients exposed to heparin due to the production of platelet factor 4-heparin antibodies. Many patients have PF4 antibodies without clinical evidence of HIT. Thus functional testing is required to determine the clinical significant of these antibodies in an individual patient. These antibodies are typically of the IgG type and wane over the course of three months. Thus, patients with clinically insignificant antibodies or a remote history of HIT are often candidates for heparin anticoagulation during bypass. Low levels of antithrombin III (ATIII) due to young age or depletion from thrombosis lead to heparin resistance that can often be overcome with increased heparin dose or administration of FFP, cryoprecipitate, or antithrombin concentrate to provide additional ATIII.
Alternative strategies for anticoagulation in patients with a contraindication to heparin include plasma exchange to remove antibodies prior to heparinization or use of an alternative anticoagulant such as bivalirudin or argatroban. Argatroban is a direct thrombin inhibitor that undergoes hepatic metabolism with a half-life of 45 minutes. Anticoagulation with argatroban can be evaluated with ACT or PTT monitoring, however the optimal dosing and goals for monitoring are unclear and clots often form despite an apparently adequate ACT.
Argatroban has no reversal agent, so hemostasis after bypass is time-dependent and significant bleeding is often encountered. Given argatroban’s multiple shortcomings, many institutions prefer to use bivalirudin, an alternative direct thrombin inhibitor. Bivalirudin is metabolized by proteolysis and excreted by the kidneys with a half-life of 25 minutes. Monitoring may be done by ACT or less commonly by factor IIa activity or rotational thromboelastography. Bivalirudin can be removed by hemofiltration, so modified ultrafiltration after cardiopulmonary bypass can be helpful in achieving hemostasis. Data to guide use of these anticoagulants in children is limited and future multisite data exchange is essential to determine the optimal drug and optimal monitoring and reversal strategy for children undergoing cardiac surgery.
Questions
For Dr. Williams: What are your thoughts on giving these factors during rewarming on bypass?
Answer: There are case reports of administration of fibrinogen concentrate during rewarming causing thrombosis.
For Dr. Williams: Comment of the safety and timing of these factors
Answer: Some experts suggest giving FFP on bypass to increase the level of anticoagulants if you are planning to use PCCs post-bypass. Others suggest that giving PCCs and then FVIIa is beneficial as you establish a baseline level of factors to facilitate action of FVIIa. There is insufficient data to establish safety.
Session III: Focus on a lesion: Transposition of the Great Arteries
Scott G. Walker, MD (Riley Hospital for Children, Indianapolis) introduced the speakers for the excellent annual review of a specific cardiac lesion including anesthetic and surgical considerations.
Gregory Latham, MD (Seattle Children’s, Seattle) began the discussion for Transposition of the great arteries (TGA) describing an incidence of 7% and a higher prevalence in males. TGA is classified into three subtypes: TGA-Intact Ventricular Septum (IVS) being the most common, TGA-Ventricular septal defect (VSD), TGA-VSD-Left Ventricular Outflow Tract Obstruction (aka TGA-PS). In TGA–IVS, intercirculatory mixing depends on the size and location of shunts. Saturation is determined by the degree of mixing rather than the amount of pulmonary blood flow. A reverse differential cyanosis can be present after birth with elevated pulmonary blood flow. In TGA-VSD, there is bidirectional mixing through VSD and saturations are usually above 80% In TGA-VSD-LVOTO, pulmonary blood flow is limited with presentation of severe cyanosis without heart failure. Neonatal physiology is similar to TOF/PA.
Algorithm for preoperative management includes starting prostaglandins, PGE1 and completing an echocardiogram to guide the decision for balloon atrial septectomy (BAS) vs early surgical management. There is no clear association between the risk of stroke and BAS. The echocardiogram should include an inspection of the great vessels, ventricular septum, outflow obstruction, coronaries, and the presence of a restrictive atrial septum defect.
Anesthetic management should focus on presence and/or persistence of pulmonary hypertension, managing the balance between systemic and pulmonary vascular resistances and the management of hypoxic episodes if they occur.
Risk factors for poor outcome include restrictive atrial septum, persistent pulmonary hypertension, low birth weight/prematurity, and a late diagnosis. Post bypass considerations include inotropic support, afterload reduction, coagulopathy, sinus rhythm, transesophageal echocardiogram to evaluate coronary blood flow. Five to seven percent of TGA survivors have coronary obstruction on angiography without obvious clinical manifestations of ischemia.
Max Mitchell, MD (University of Colorado Denver, Aurora), a pediatric cardiac surgeon, presented his perspective on surgical management of transposition of the great arteries. The talk started with a discussion about the ventricular-arterial discordance and the parallel circulation in TGA patients. Mixing is a requirement for survival.
The atrial switch was done in 1957 by Senning followed by the Mustard procedure in 1963. Both procedures have long term complications including dysrhythmias, baffle obstruction and RV failure. The arterial switch was first done by Jatene in 1975. The first neonatal switch was done by Dr. Castaneda at Boston Children’s Hospital in 1983. By the late 1980s, the neonatal arterial switch became the gold standard surgical procedure for TGA. Coronary anatomy is extremely variable and three different classifications exist: Yacoub, Leiden and Lannelongue. The Marie Lannelongue “French” classification is the most simple and guides coronary surgical transfer techniques. The repair for TGA starts with the LeCompte maneuver followed by the coronary transfer depending on the origin and paths of the coronaries. Then the neo-pulmonary artery reconstruction with autologous pericardium is completed.
The STS database shows mortality 1.8% from 2011-2014. Risk factors for early mortality include a low surgical volume (center and surgeon) and a complicated coronary anatomy including intramural left coronary artery or a single coronary.
Questions
Question for Dr. Mitchell: What are your thoughts about public reporting of outcomes?
Answer: This is reality now. We were early adopters of public reporting. It is unfortunate that the public does not really understand the impact of risk spectrum and comorbidities which don’t show up in reporting.
Question for Dr. Latham: Dr. Nicolson mentioned a center that routinely extubates patients early following an arterial switch operation (ASO). Is this feasible?
Answer: Could be feasible in some patients but it requires a consensus from the multidisciplinary team.
Dr Nicolson commented that the plan is to extubate all patients coming with a natural airway and with a stable intraoperative course. 95% of the cases at CHOP are extubated in the operating room. She continues to mention that high dose narcotic anesthetic technique precludes early extubation.
Afternoon Sessions
Session IV: Selected Posters for Oral Presentation
The afternoon kicked off with selected oral presentations moderated by Jeremy Geiduschek, MD (Seattle Children’s Hospital, Seattle).
Lawrence Schwartz, MD (Children’s Hospital Colorado, Aurora) presented an analysis of trends in the perioperative use of dexmedetomidine in pediatric patients with congenital heart disease. According to the CCAS-STS Congenital Heart Disease Database, dexmedetomidine use in congenital cardiac surgery has increased dramatically from 27% of cases in 2010 to 40% of cases in 2013. There was significant variation between centers, with some centers using dexmedetomidine in nearly all cases and some centers with no use. Dexmedetomidine was used preferentially in older patients and those undergoing less complex surgery.
Patients who received dexmedetomidine had a lower incidence of complications; however, this was likely due primarily to selective use of dexmedetomidine in lower risk patients. Nonequivalence of the groups of patients with and without dexmedetomidine precluded determination of outcome differences attributable to dexmedetomidine.
Dheeraj Goswami, MD (Texas Children’s Hospital, Houston) followed with an analysis of his department’s experience utilizing a goal directed pathway for blood product utilization during cardiac surgery. In collaboration with the transfusion medicine department, Dr. Goswami’s group developed a rotational thromboelastography-guided transfusion algorithm with the goal of decreasing cryoprecipitate wastage. Compared with the 7-month period before introduction of the guideline, average cryoprecipitate waste decreased from 43.4 to 12.7 units per month.
They also demonstrated a sustained decrease in cryoprecipitate wastage and a trend toward decreased cryoprecipitate administration after guideline implementation. Future studies plan to look at trends in the use of other blood products.
The presentations concluded with an analysis of an evidence-based guideline for OR extubation after pediatric heart surgery by Raina Abbasi, MD (Riley Hospital for Children, Indianapolis). After a comprehensive review of the literature, Dr. Abbasi’s group developed a set of exclusion criteria for extubation in the operating room after heart surgery. Exclusion criteria included age less than one month, use of deep hypothermic circulatory arrest, STAT mortality category 4 or 5, history of airway anomaly, emergent procedure, bypass duration greater than 150 minutes, significant intraoperative bleeding, intraoperative respiratory difficulties, dopamine greater than 5 mcg/kg/min or any use of epinephrine. They found that use of these criteria resulted in a reduction in the rate of OR extubation from 60% to 45% and a reduction of extubation failure from 2.9% to 1.2%.
Interestingly, the one patient who required reintubation after the guideline was developed was a STAT mortality category 4 case and a deviation from the protocol. Time from skin closure to OR departure was unchanged. They concluded that evidence-based guidelines for extubation may decrease practice variation and extubation failure without a significant effect on OR utilization.
Session V: Adult Congenital Heart Disease (ACHD)
The general sessions concluded with an engaging discussion of the rapidly developing field of adult congenital heart disease, moderated by Robert Seal, MD (Stollery Children’s Hospital, Alberta).
Viviane Nasr, MD (Boston Children’s Hospital, Boston) began the session with a description of trends and outcomes in the growing population of adults with congenital heart disease (CHD). With dramatic improvement in surgical techniques and perioperative care, the number of children with heart disease surviving to adulthood has rapidly increased. The number of adults living with CHD increased from 17,911 in 1985 to 23,536 in 2000. This has lead to a shift in the CHD population as adults have become an increasingly large proportion of this population. Unfortunately, development of resources to care for these complex patients has lagged behind, leading to significant challenges in providing high quality care.
ACHD patients face all of the typical sequelae of pediatric heart surgery in addition to age-related phenomena that may be unfamiliar to many pediatric providers. Common causes of mortality in these patients include dementia, GI bleed, chronic renal disease, heart failure, chronic obstructive pulmonary disease and myocardial infarction. Unsurprisingly, patients with more complex heart lesions face increased risk of morbidity and mortality. ACHD patients experience exercise intolerance and heart failure symptoms similar to elderly patients with acquired heart disease. Although there are obvious benefits to exercise training and physical activity, ACHD patients often face confusion regarding the optimal level of physical exertion. Assessment of baseline functional status, physical examination, and noninvasive testing are helpful in guiding patients to an appropriate exercise regimen.
The optimal setting and personnel to care for ACHD patients is still unclear and there is significant variability in institutional practice. The transition from pediatric to adult care can be fraught with difficulties including financial and insurance questions and lack of available ACHD providers. In the future, development of regional centers for ACHD and registries for multisite collaboration will hopefully expand the resources available to this growing population of complex patients.
Luis Zabala, MD (Children’s Medical Center Dallas, Dallas) continued the session on ACHD with a discussion of the important role of a perioperative surgical home in this group of patients. Survival from birth to 18 years in patients with CHD has increased from 81% in the early 1970s to 90% in the early 1990s, resulting in a disproportionate increase in the cost of health care for patients with CHD. From 1998 to 2005, there was a 127% increase in charges per hospitalization to a total of $3 billion in 2005. 69% of the costs are related to management of medical issues, 20% for cardiac surgery, 8% for noncardiac surgery, and 3% for cardiac catheterization. Common causes of hospitalization include arrhythmia, coronary artery disease, and heart failure.
These complex patients often present for surgery with incomplete records and inadequate preoperative evaluation leading to costly and inconvenient surgical delays. Thus, the concept of a perioperative surgical home (PSH) championed by the ASA is particularly important in this group of patients. A multidisciplinary collaborative approach to care coordinated by anesthesiologists has the potential to improve patient outcomes, increase patient satisfaction, and decrease costs. Coordination through a PSH will ensure the availability of appropriate records and facilitate preoperative risk-stratification and clinical optimization.
To address these goals, Dr. Zabala’s group at Children’s Medical Center Dallas developed the role of Cardiac Anesthesia Coordinator.
In collaboration with the preoperative assessment clinic, the Cardiac Anesthesia Coordinator reviews cases, ensures adequate preoperative evaluation, provides risk stratification, determines the appropriate postoperative disposition, and coordinates communication between members of the care team. This will presumably reduce fragmentation of care and unnecessary repeated anesthetic exposure and will lead to improved outcomes and decreased cost.
Carrie Rydin, MBA concluded the session by sharing the inspiring story of her journey through life with congenital heart disease. Carrie was born without a prenatal diagnosis of heart disease, but was found to have a murmur at her 6 week pediatric checkup. She was subsequently diagnosed with double outlet right ventricle and had her first heart surgery at the age of 2 ½. As Carrie recovered from a series of surgeries in childhood, she began to feel like a normal child and considered herself “fixed.” After developing syncope with exertion at the age of 21, Carrie discovered that she had developed sick sinus syndrome as a result of her CHD and required implantation of a pacemaker and AICD. As many young adults with CHD, Carrie felt isolated as she was one of the oldest patients at the children’s hospital yet far younger than most adults dealing with similar medical issues.
Managing the transition from pediatric to adult care can be stressful for young adults struggling to navigate a multitude of psychological, medical, and practical challenges. Prominent issues include body image concerns, fear and uncertainty surrounding exercise, family planning, difficulty obtaining adequate health insurance, and difficulty locating experienced ACHD providers.
The development of national guidelines and standards for management of ACHD are crucial as this population expands in the coming years. Pediatricians can empower young adults with CHD as they transition from parent-driven care to self-driven care. Carrie implored physicians, patients, and policy makers to work together to develop standards and accreditation programs to ensure quality care for all adults living with congenital heart disease.
Session VI: Fireside Chat
James A. DiNardo, MD (Boston Children’s Hospital, Boston) and Emad Mossad (Texas Children’s Hospital, Houston) moderated this educational and interactive session.
Paul Firth, MD (Massachusetts General Hospital, Boston) anesthesiologist and high altitude mountain climber discussed consideration of high altitude and congenital heart disease by presenting case scenarios. The first scenario described the Endurance expedition to Antartica led by Sir Ernest Schackleton who suffered repeated attacks of breathlessness and weakness and finally diagnosed 100 years after his death with having an atrial or ventricular septal defect. The second scenario focused on high altitude syndrome and high altitude pulmonary edema. It is important to note that the amount of oxygen is the same at sea level and at high altitude. The lactate at high altitude is lower following exhaustion and described as the lactate paradox in humans at high-altitude physiological performance.
Hilary Grocott, MD (University of Manitoba, Manitoba, Canada) reviewed neuro-monitoring and its benefits during cardiac surgery. The first description of spectrophotometry was 1954 followed twenty years later by a description of NIRS in Science in 1977. In 1993, Somanetics was the first NIRS approved by the FDA followed by additional cerebral oximetry devices. Multiple studies have been done assessing the relationship of NIRS with oxygenation. Interventional algorithms showed better outcomes overall including renal outcomes without evidence of improvement of cerebral outcomes.
Proposed interventions are as follows: Verify head position, inspect cannula position following cannulation, increase blood pressure, increase fractional inspiratory oxygenation, increase hemoglobin/transfusion, increase cardiac output and pump flow when on bypass, and decrease cerebral metabolism.
Further studies defining the association of NIRS measurement with neurologic outcomes are needed. The current use of NIRS may be limited to trending and management but not diagnosis.
The meeting concluded with a poster session and a reception. We are looking forward to another informative and educational meeting next year in Austin, Texas.
