Meeting Reviews

Session III: Best Abstracts for Oral Presentation

By Destiny F. Chau, MD

Moderator: David F. Vener, MD (Texas Children’s Hospital, Houston, TX)

Five abstracts with the highest scores were chosen for virtual video oral presentations this year. Below is a brief description for each of the presented posters.

Title: Implementation of a Preoperative Anemia Clinic for Pediatric Cardiac Surgical Patients: A Single Center Experience
Authors: Otsuka Y, Naraine N, Switzer T, Faraoni D (The Hospital for Sick Children, Toronto, Ontario, Canada)

Description
Dr. Otsuka presented institutional data after the implementation of a preoperative anemia clinic. He began by stating the association of blood transfusion with adverse events and that blood transfusions should be minimized. The authors aimed to analyze the association between preoperative iron treatment, preoperative hemoglobin, and perioperative red blood cell transfusion in children undergoing cardiac surgery following the implementation of a preoperative anemia clinic.

The study was retrospective and included patients undergoing cardiac surgery with cardiopulmonary bypass in 2013 and excluded patients younger than three months of age and those preoperatively admitted to the cardiac intensive care unit. Collected data included demographic variables, perioperative laboratory results, blood transfusion details, and surgical characteristics. Univariable and multivariable logistic regressions were done for data analysis. The primary outcomes were preoperative hemoglobin levels and perioperative red blood cell transfusion.

A total of 201 children receiving preoperative iron supplementation were compared to 95 children who did not receive iron supplementation (control group). Children in the iron supplementation group were older (1047 days vs 260 days), had higher body weight (13 vs 6.5 kg) and height (92 vs 66 percentile), and had higher baseline oxygen saturations (98% vs 96%) compared to those in the control group. Other characteristics such as the type of surgery, percent of reoperative procedures, congenital heart disease lesion including single ventricle physiology, and cardiopulmonary bypass duration were comparable in both groups.

The results demonstrated that children receiving iron supplementation compared to the control group had the following:

Higher preoperative hemoglobin levels, 13.9 g/dL vs 12.9 g/dL
Similar exposure rate to red blood cell transfusion (50% vs 61%). Dr. Otsuka mentioned this might be related to the blood added to the cardiopulmonary bypass prime for all children under 10 kg.
Decreased transfused red blood cell volume, 1.4 mL/kg vs 12.5 mL/kg
Decreased autologous blood cell volume, 11.0 mL/kg vs 17.0 mL/kg
Comparable hemoglobin levels after surgery, 12.8 g/dL vs 13.4 g/dL and at discharge 11.3 g/dL vs 11.6 g/dL.

In conclusion, this study showed that preoperative iron supplementation was associated with higher preoperative hemoglobin levels and could help reduce the volume of red blood cell transfusions in the perioperative period. This study was limited by its retrospective nature and small number of patients.

Title: Effect of Previous Cardiac Surgery on Mortality Following Non-Cardiac Surgery in Children
Authors: Sisney J, Mpody C, Tobias J, Nafiu O (Nationwide Children's Hospital, Columbus, OH, USA)

Description
Dr. Sisney highlighted that children with congenital heart disease (CHD) undergoing non-cardiac surgery have increased risk of perioperative cardiorespiratory complications as well as 30-day mortality compared to those without CHD. The impact of prior cardiac surgery on mortality risk during subsequent non-cardiac surgery is undetermined. This study evaluated the association of previous cardiac surgery on 30-day postoperative mortality risk in children undergoing inpatient, non-cardiac surgical interventions.

The authors performed a secondary data analysis of a previous retrospective cohort of children from the National Surgical Quality Improvement-Pediatric (NSQIP-P) database between the ages of one month and 18 years, who had inpatient surgery between 2012 and 2018 (n=312,205). The primary exposure measure was history of prior cardiac surgery. The 30-day postoperative mortality of children with and without history of prior cardiac surgery undergoing inpatient non-cardiac surgery was compared.

History of prior cardiac surgery was present in 12,475 (4.0%) children. Overall, the mortality rate was 0.59 per 1000 children-days. The 30-day postoperative mortality was higher for children with history of prior cardiac surgery at 1.46 per 1000 children-days vs 0.51 per 1000 children-days for those who did not have history of prior cardiac surgery. After controlling for baseline covariates, history of prior cardiac surgery conferred a two times greater risk of mortality. Children with history of prior cardiac surgery had lower survival probability and longer duration of postoperative hospital stay.

In conclusion, history of prior cardiac surgery in children was associated with higher risk of postoperative mortality and longer duration of post-surgical hospital stay in children undergoing inpatient non-cardiac surgical procedures.

Title: Small Volume Bolus of Papaverine Versus Heparin to Maintain Patency of Peripheral Arterial Catheters in Pediatric Patients Undergoing Cardiac Surgeries: A Randomized Double-blind Controlled Trial
Authors: Gautam N, Edmonds K, Pawelek O, Rydalch E, Griffin E, Hubbard R, de Silva A, Salazar J, Hoffman C (UT Health Houston, Houston, TX, USA; UT Houston, Houston, TX, USA)

Description
Dr. Gautam described the factors affecting the accuracy of arterial line waveforms. The arterial line transducer senses the arterial waveform and breaks down the complex waveform into fundamental waves. The system remains vulnerable to resonance, excessive amplification and dampening. Patient factors such as arterial vasospasm, arterial clot, catheter malposition or occlusion, and ratio of artery-to-catheter size causing over-dampening can affect the accuracy of peripheral arterial line waveforms. Other factors relate to the flush solution used to maintain arterial line patency. Extrapolating the use of continuous infusion of papaverine to maintain arterial line patency in the intensive care unit, the authors hypothesized that a single bolus of intraluminal papaverine administered immediately after peripheral arterial line placement can improve arterial waveform characteristics and enhance patency.

This study was a single-institution, prospective, randomized, double-blinded trial in pediatric patients younger than 17 years who had arterial catheters placed for open heart surgery. The equipment for arterial cannulation and transducing systems were standardized. Immediately after inserting a peripheral arterial line, arterial waveform characteristics were noted, which included the following: 1) presence of a dicrotic notch, 2) absence of cavitation during sampling and presence of one to two post-flush oscillations after the square wave test, 3) evidence of a color change at the catheter site when the line was flushed, and 4) ease of aspirating a standardized two mL blood sample in 30 secs was recorded. Following this, one mL of a drug was randomly administered, heparin 2 units/mL versus papaverine 0.12 mg/mL. Hemodynamics and arterial wave characteristics (same as those recorded after arterial line insertion) were recorded at 5 minutes and 60 minutes later. If the arterial waveform was not optimal at 60 minutes, another second randomized drug bolus was administered with waveform and data assessed 5 minutes after the second bolus. At this time, if the arterial waveform was still suboptimal, rescue papaverine was administered.

One hundred patients were enrolled, and 88 patients had complete datasets for analysis. Out of the 12 who were excluded, two patients in the heparin group had their catheters replaced due to arterial spasm vs zero in the papaverine group. At baseline, groups were similar in terms of arterial line patency. Five minutes after administering the research syringe of drug, improved arterial line patency and waveforms were observed in the papaverine group compared to the heparin group (64% vs 39%); at 60 min, arterial line patency was comparable in both groups (71% vs 61 %). However, 37% of patients in the heparin group compared to 17% in the papaverine group required papaverine rescue to improve arterial line characteristics. The response to the rescue dose in the heparin group was increased compared to the response of the papaverine group (28% vs 7%).

In summary, papaverine injection immediately after peripheral arterial catheter placement in pediatric patients undergoing cardiac surgery was associated with improved initial arterial line patency. This drug was further associated with improved arterial patency when used as a rescue medication.

Title: Examining an Urban Myth: Do Patients with Down Syndrome Require Greater Amounts of Analgesic and Sedative Medications during and after Pediatric Cardiac Surgery?
Authors: Vogel E, Staffa S, DiNardo J, Brown M (Mayo Clinic, Rochester, MN, USA and Boston Children's Hospital, Boston, MA, USA)

Description
Dr. Vogel presented the study examining the urban myth that patients with Down Syndrome require greater amounts of analgesic and sedative medications compared to their peers without Down Syndrome. This myth may be based on the difficulty of ensuring adequate pain control in children with Trisomy 21 due to variable pain thresholds. Prior studies evaluating analgesic dosing in children with Down Syndrome have had limited and mixed results. This study aimed to determine whether children with Down Syndrome received higher doses of opioid medications compared to children without Down Syndrome undergoing complete atrioventricular canal repair. A retrospective chart review was done on children younger than two years of age who underwent repair of a complete atrioventricular canal between 2009 and 2019. Exclusion criteria included diagnosis of unbalanced atrioventricular canal and children who had staged biventricular procedures for repair. The primary outcome was oral morphine equivalents (OME) received in the first 24 hours after surgery. Secondary outcomes included intraoperative OMEs and OMEs at 48 and 72 hours, dosing of non-opioid analgesics and sedative medications, pain scores, time to extubation, length of stay, and death.

There were 151 children included, 131 in the Trisomy 21 and 24 in the non-Trisomy 21 group. Preoperative baseline characteristics were comparable between groups except for age which was higher in the Trisomy 21 group with a median of 96.3 days vs 75.9 days in the non-Trisomy 21 group. Other variables including median weight, sex, exposure to preoperative medications such as opioids and diuretics were no different between groups. Intraoperative variables such as cardiopulmonary bypass and aortic cross clamp time and intraoperative doses of ketamine, fentanyl, midazolam, and morphine were similar between groups.

For the primary outcome measure, there was no difference in OME received in the first 24 hours postoperatively between the Trisomy 21 and non-Trisomy 21 groups (median 3.01 mg/kg vs 3.57 mg/kg). Interestingly, OMEs were lower in the Trisomy 21 group compared to the non-Trisomy 21 group at 48 h (median 0.52 mg/kg vs 2.16 mg/kg) and 72 h (median 0.31 mg/kg vs 0.58 mg/kg). Similar amounts of non-opioid analgesics and sedation were given to both groups of patients at all time points. There were no significant differences in other parameters including pain scores, days to extubation, days hospitalized, or other postoperative complications.

Although the OMEs at 48 h and 72 h were statistically lower in the Trisomy 21 patients, the authors highlight that the doses are clinically similar and caution against using this finding to lower opioid administration in Trisomy 21 patients.

In conclusion, this study suggests that patients with Trisomy 21 undergoing common atrioventricular canal repair did not show increased analgesic or sedative requirements compared to a group of children without Trisomy 21. This correlates well with prior data demonstrating no difference in clearance of morphine in this patient population.

Title: Comparative Incidence of Perioperative Adverse Events in Infants With and Without Congenital Heart Disease Undergoing Gastrostomy Tube Placement

Authors: Brown L, Knio Z, Kim W, Durieux M, Naik B, Castro B, Sharma R (University of Virginia Health, Charlottesville, VA, US)

Description
Dr. Brown introduced the topic by presenting data that children with congenital heart disease (CHD) undergoing non-cardiac surgery frequently experience adverse perioperative events. It is estimated that 30% of children with CHD will undergo non-cardiac surgery before the age of five years old. The authors aimed to understand the incidence of perioperative adverse events in their institution’s CHD infant population undergoing gastrostomy tube placement and compared this incidence with the non-CHD infants undergoing the same surgery.

The authors performed a retrospective chart review of all infants less than one year old undergoing open or laparoscopic gastrostomy tube placement at the University of Virginia Children’s Hospital from January to December 2019. The patients were divided into CHD infants and control infants. The incidence of perioperative cardiac and respiratory adverse events was compared between groups. Hypotension was defined as a 20% decrease from baseline mean arterial blood pressure (MAP). Baseline MAP was an average of all MAPs available within 30 days preoperatively. Univariate testing was applied to investigate differences in patient characteristics and operative events between the two study groups.

A total of 37 infants (23 CHD and 14 controls) underwent gastrostomy tube placement and were analyzed. Groups were matched for gestational age at birth, sex, age at time of procedure, and syndromic diagnosis. Compared to patients without CHD, the patients with CHD had a greater ASA class. There were no differences in the incidence of inotrope use, cardiac arrest, bronchospasm or laryngospasm, difficult intubation, failed extubation, arterial desaturation, or escalation of care from non-ICU to ICU. The incidence of hypotension was 78% in the CHD and 85% in the control group. Further analysis of the hemodynamic profiles of each group revealed that the CHD group experienced less hypotension in cumulative minutes (18.83 min vs. 38.71 min), in terms of percentage of time of the total procedure (0.26 vs. 0.59), and in terms of mmHg x minutes below goal (88.03 vs. 292.71). Also, CHD infants were less likely to have the attending anesthesiologist simultaneously staffing two operating rooms (52.2% vs. 92.9%).

In conclusion, the hemodynamic profile comparison revealed that CHD infants spent less time being hypotensive (both in total minutes as well as percentage of time of the procedure) when compared to infants without CHD. Given their higher ASA status and anesthetic risk, the opposite was expected. This result could be explained by the increased propensity to treat hypotension in the CHD group given the limited cardiovascular reserve in this patient population as well as a lower ratio of attending to case staffing in instances of patients with CHD at our institution.