Annual Meeting Summary
By Greg Latham, MD & Jeremy Geiduschek, MD
Department of Anesthesiology and Pain Medicine
Seattle Children’s Hospital
University of Washington School of Medicine
Seattle, WA
On Thursday, February 23, 2012, the spring meeting of Congenital Cardiac Anesthesia Society (CCAS) was convened at the Marriott Waterfront Hotel in Tampa, Florida. The meeting was very well attended with a great program put forth by Drs. James DiNardo, Jumbo (G.D.) Williams, and Wanda C. Miller-Hance.
Session I: “Oxygen: The Elixir of Life and Death” was moderated by Dr. Chandra Ramamoorthy (Stanford University).
The session started with Dr. Francis McGowan (Medical University of South Carolina) providing a whirlwind review of “Oxidative Stress and End-Organ Injury: Basic Science and Clinical Perspective.” He started by asking the audience what the standard practice is for maintaining the PaO2 during CPB. 56% responded 150-200 mmHg and 39% responded 250-500 mmHg. 75% in the audience do not routinely reduce the PaO2 during CPB for cyanotic infants and children. The talk was loaded with information regarding the role of reactive oxygen species (ROS) in causing cell injury as well as in regulating cellular homeostasis in hyperoxic, normoxic, hypoxic and anoxic environments. Possible mechanisms for hyperoxic lung injury and retinopathy of prematurity (both mediated by ROS) were presented, as well as recent work involving measuring biomarkers to determine extent of ROS-mediated damage both in vitro and in vivo. The talk concluded with presentation of data that suggest that re-inflating the lungs following CPB should be done with air and also hinted that CPB strategy should be to keep the PaO2 less than 150 and possibly lower for cyanotic infants.
Dr. Wally Carlo (Division of Neonatology, University of Alabama at Birmingham) followed with his talk, “Supplemental Oxygen in the Perinatal Period: Friend or Foe?” He began by asking the audience what target SpO2 would be used for a term neonate undergoing exploratory laparotomy? 84% responded 91-94% and 16% responded 95-97%. A follow-up statement “A premature infant has better outcome if SpO2 is maintained at 91-94% compared to 95-98%” was considered true by 69% and false by 31% of attendees.
Dr. Carlo reviewed recent clinical studies to help guide informed decision making regarding the use of supplemental oxygen, at birth, in the neonatal period for premature infants and briefly in the perinatal period and during cardiac surgery. This included a review of studies that led to the AAP recommendation to administer 100% oxygen during neonatal resuscitation if there is bradycardia at 90 seconds of age regardless of concentration of oxygen administered during the first 90 seconds. For infants born at less than 32 weeks gestation, Dr. Carlo says the evidence supports starting with 100% oxygen and titrating down to prevent hyperoxia.
Dr. Carlo was one of the investigators in the SUPPORT Trial. Infants of 24-27 weeks gestation were assigned to one of two target SpO2 ranges (85-89% vs. 91-95%) using novel methods to keep caregivers blinded to patient study arm. There was no difference in the combined outcomes of severe ROP and death. The low SpO2 group had significantly less ROP but also had significantly higher mortality. The lower SPO2 group had less oxygen use at 36 weeks corrected age and otherwise there was no difference between groups for other pulmonary outcomes, PDA, IVH, PVL, or NEC. If results of the SUPPORT Trial are combined with the BOOST II studies from the UK, Australia and New Zealand, there is additional supportive evidence to target SpO2 in the range of 91-95%. Dr. Carlo also discussed results of the STOP-ROP and BOOST studies both indicating that there are no benefits to targeting SPO2 >95% and that this approach can be harmful.
A lively Q and A followed:
Question: Does one need to pay attention to the blood tension of carbon dioxide? Does CO2 counter the effects of ROS?
Carlo: The SUPPORT Trial had a randomization arm involving CO2. There was no significant interaction found with measured outcomes.
McGowan: Acidosis may be protective up to a point.
Question: What do you do if the NIRS is 30-40 and lactate is elevated?
McGowan: Aim to keep NIRS >40% so give oxygen
One audience member urged caution in interpreting results of these studies where subjects are being transfused with adult blood.
Question: Both lecturers were asked what are some potential emerging therapies for oxygen-mediated injury?
McGowan: Possibly allopurinol or n-acetylcysteine
Carlo: Superoxide dismutase will likely be shown to be of no benefit.
Session II: “Emerging Technologies: Pulse Pressure Analysis and Non-Invasive Cardiac Output Measurement” was moderated by Wanda C. Miller-Hance (Texas Children’s Hospital)
Dr. Maxime Cannesson (University of California, Irvine) delivered the first talk titled “Pulse Pressure Analysis in Children: Past, Present and Future.” Audience members use a wide range of methods to predict fluid bolus responsiveness. 50% use a combination of heart rate and arterial pressure, 26% use pulse contour, 16% CVP, 2% urine output and 5% some other means. When asked about pulse pressure variation, 41% use this frequently to determine fluid responsiveness while 48% consider it helpful in adults and of limited value in children. 7% do not believe in it and 4% have never heard of it.
Dr. Cannesson reviewed the physiology of altering stroke volume in response to volume expansion, how best to predict responsiveness and some of the pitfalls in trying to transfer these principles from adult patients to children. In intubated adults there is a relationship between an increase in peak airway pressure leading to decrease venous return, a drop in RVEDV, RV stroke volume, then LVEDV and finally a drop in LV stroke volume. During cyclic ventilation this will be evident in pulse contour analysis of an arterial pressure tracing.
This chain of events is much less predictive in children due to their increased chest, lung and vascular compliance. For this reason, Dr. Cannesson indicates that echocardiography measured stroke volume remains the best method to determine fluid responsiveness in children.
Dr. Katherine Taylor (Hospital for Sick Children, Toronto) followed with a lecture on “Non-Invasive Cardiac Output Monitoring in Children.” 61% of the audience was not aware of non-invasive methods for cardiac output (NI-CO) determination being commercially available. The five types of NI-CO devices available were presented (Doppler, pulse pressure, impedance cardiography, partial CO2 rebreathing, and plethysmography variability index). The principles of how each are used to determine CO was presented as well as some of the commercially available options within each category. There is currently some good evidence for improved outcome in adult patients who have NI-CO monitoring for goal directed therapy. Data are lacking for children though studies are underway.
Session III: “Sickest of the Sick, Non-Cardiac Surgery” was moderated by Dr. Helen Holtby (Hospital for Sick Children, Toronto) and included three case presentations that would test the coronaries of even the best of us. Scott Watkins (Vanderbilt University) led off with “The Fontan Patient for Posterior Spinal Fusion.” Abnormal physiology is present in virtually all organ systems in Fontan patients. The requirements imposed by having a prolonged, bloody procedure in the prone position with limited anesthetic choices due to spinal cord integrity monitoring create significant challenges. Dr. Mark Twite (Children’s Hospital Colorado) followed with a case of a five year old having a “Pulmonary Hypertensive Crisis During Broviac Catheter Placement.” His thorough review of pathophysiology of PH and management strategies to prevent a PH crisis and how to treat one should it occur could also serve as a cautionary tale -- pediatric patients with PH have a significantly higher mortality rate during an anesthetic compared with other children. Dr. Peggy P. McNaull (University of North Carolina) presented the final case titled: “Laparoscopic Nissen Fundoplication in a 3-Month Old s/p Norwood Procedure.” In spite of several theoretical potential contraindications to lengthy laparoscopic procedures in Norwood patients, Dr. McNaull presented a review of positive outcome results from several centers and outlined a strategy to use in providing anesthesia for this procedure.
At mid-day the audience adjourned for a sumptuous Mexican themed buffet lunch. During the meal, Dr. David Veener (Texas Children’s Hospital) presented the “STS-CCAS Database Update: Well on Our Way (or Down the Rabbit Hole of Data).” As of the fall of 2011 there are 26 programs that have paid the fee to submit anesthesia data (there are 94 surgical program participating). Most are submitting only data for CV surgery cases. A brief review of the first 18 months of anesthesia related data was presented followed by a summary of suggestions for improvements to the data gathering tools.
Afternoon Session
Session IV, “Poster presentations,” was moderated by Dr. Courtney Hardy (Children’s Memorial Hospital). The three best posters were orally presented. These included “An educational simulation of hypoplastic left heart syndrome” by Pitkin A, Lizdas D, and Lampotang S (University of Florida); “Fluid Overload Predicts Morbidity and Mortality in Neonates Following Cardiac Surgery” by Wilder N, Blatt N (University of Michigan), and “Increasing Cumulative Exposure to Inhaled Volatile Anesthetic Agents is Associated with Poorer Neurodevelopmental Outcomes after Cardiac Surgery in Infancy” by Diaz L, Rehman M, Luan X, Gerdes M, Bernbaum J, Nicolson S, Gaynor J (The Children’s Hospital of Philadelphia). All of the accepted abstracts that were presented at the meeting may be viewed on the CCAS website.
Session V, “Recombinant Factor VIIA: Use or Abuse,” was moderated by Dr. Jumbo Williams (Stanford University Medical Center). Dr. Williams began the session with a review of the mechanism of action of recombinant activated factor VIIa (rFVIIa) and discussed the increasing use of rFVIIa in post-bypass coagulopathy. He discussed the 2009 CCAS rFVIIa Taskforce’s consensus recommendations on indications for use, efficacy, dosing, monitoring and safety of rFVIIa for pediatric cardiac surgery. However, levels of evidence in the literature are weak and the recommendations are offered to assist practitioners and stimulate debate.
Dr. Susan Staudt (Children’s Hospital of Wisconsin) graciously filled in at the last moment and took the “Pro” side of the argument. She discussed the dramatic 140-fold increase of off-label use of rFVIIa in hospitals since 2008, which represents 97% of hospital usage. Dr. Staudt reviewed two recent retrospective studies that demonstrated a statistically significant reduction in blood loss and transfusion requirements in pediatric cardiac surgery patients. However, there was no difference in intensive care unit or hospital length of stay or mortality between groups. In both studies, no thrombotic complications occurred. A recent review of 29 publications evaluating rFVIIa use in pediatric cardiac surgery patients also demonstrated a statistically significant reduction in blood loss after rFVIIa.
She poked fun at her on-stage opponent, Dr. Guzzetta, because Dr. Guzzetta has published a case series of the effectiveness of rFVIIa, indicating that she also uses rVIIa for refractory bleeding. Lastly, Dr. Staudt argued that only minor complications have been reported with the use of rFVIIa in this setting, which reflects her institution’s experience. She concluded that rFVIIa is extremely effective in decreasing post-bypass bleeding and that there is little evidence to prove that the drug causes disastrous coagulopathy.
Dr. Nina Guzzetta (Children’s Healthcare of Atlanta) presented the “Con” session. She reviewed the literature, including the three articles discussed by Dr. Staudt, arguing that most of the available studies are retrospective, small in size, and all but one lacks case controls. Taken together, these studies do suggest that rFVIIa is effective in reducing post-bypass bleeding, but the evidence to support its efficacy is poor. The one randomized controlled trial of rFVIIa versus placebo in 76 infants reported no significant differences in any of the efficacy outcome measures or in adverse events.
Then Dr. Guzzetta argued that there are many unresolved issues with rFVIIa in pediatric cardiac surgery: (1) there is no agreed upon dosing protocol in children, and there is scant data of the pharmacokinetics in children to direct such dosing; (2) there is a lack of a laboratory assay to predict its clinical efficacy; (3) it is expensive; and (4) there are no adequately powered studies available to determine the safety of rFVIIa in children having cardiac surgery. The conclusion was that there are many unresolved issues with rFVIIa for treatment of post-bypass bleeding, and additional adequately powered studies are needed to address them.
Following was a very spirited Q&A session with the panel:
- 68% of the audience will use rFVIIa only after 3 or more “rounds” of blood product administration.
- 53% use a dose of 80-120 mcg/kg
- 49% will not use rFVIIa in a patient with a shunt
- 15% will not use rFVIIa for a patient on ECMO
- Several commented that use of rFVIIa should be according to an institution-approved protocol.
Session VI, “Disease Update: The Borderline Left Ventricle,” was moderated by Dr. Emad Mossad (Texas Children’s Hospital) and was a fascinating review of borderline hypoplastic left heart syndrome (HLHS).
The session began with Dr. Debra Kearney, (pathologist at Texas Children’s Hospital), giving an excellent presentation of the spectrum of severity of left ventricular (LV) hypoplasia and HLHS. Through the use of surgical specimen and cadaveric photos, multiple variations of LV hypoplasia were explained, including “cherry pit” LV, flat LV, miniscule LV, and borderline LV. The prevalence of other cardiac malformations associated with HLHS was reviewed.
Dr. Sitaram Emani, (Department of Cardiothoracic Surgery, Children’s Hospital Boston), spoke next about the strategic approach to evaluating children with a borderline LV and the advantages and disadvantages of a biventricular repair versus a single ventricle palliation. Conversion to a biventricular repair requires initial single ventricle palliation, maneuvers to rehabilitate the LV, and time for LV growth prior to repair. An important component of LV rehabilitation is surgical resection of endocardial fibroelastosis (EFE). Outcome studies are showing acceptable results; however, biventricular conversion still requires multiple operations and interventions. In a subset of patients that have been evaluated at Boston, approximately 1/3 have been able to go on to biventricular repair.
Dr. Wayne Tworetzky (Director of Fetal Cardiology, Children’s Hospital Boston) further discussed the single ventricle palliation versus two ventricle repair pathways at Boston. He emphasized that HLHS is progressive in utero and LV rehabilitation can begin with balloon valvuloplasty of aortic stenosis in the fetus with good results. Many strategies for LV rehabilitation are employed, including a Stansel anastomosis and BT shunt in stage 1 palliation, surgical resection or stripping of EFE, mitral and aortic valvuloplasty, creation of a restrictive atrial septum, and patience while the LV grows. A plethora of echo images were shown to neatly illustrate these points.
Session VII, “Jeopardy,” was superbly co-moderated by Drs. Anthony Clapcich (Children’s Hospital of New York) and Radhika Dinavahi (Columbia University). Electronic voting keys allowed the entire audience to participate on every question.
