Optimization of the IntraVascular Oxygenator Catheter Using Angular Oscillation.

We demonstrate a methodology which both improves oxygen transport and reduces or eliminates bubble formation in a novel hyperbaric membrane oxygenator catheter model system. Angular oscillations were introduced to a bundle of hollow fiber membranes (HFMs) supplied with hyperbaric 100% oxygen at average gauge pressures up to 0.35 barg. Oscillating bundles enabled delivery of an oxygen flux of up to 400 mL min-1 m-2 in an aqueous solution, a doubling over a previous non-oscillating setup. Similarly, the addition of angular oscillations facilitated a five-fold reduction in pressure to achieve similar oxygen flux. The increased angular speed of oscillation improved flux, while the addition of angular micro-oscillation variations resulted in flux reductions of 7-20% compared to continuous macro-oscillation only, depending on mixing conditions. However, semi-quantitative visual observation demonstrated that angular oscillations reduced or eliminated the instance of oxygen bubble formation on the HFMs. The modeled mass transfer coefficients indicated a quasi linear relationship between rotational velocity and flux, suggesting that faster oscillation speeds could further improve oxygen mass transport allowing for HFM bundles to maintain high oxygen fluxes while eliminating bubble formation. This encourages further development of our compact oxygenating catheter that could be used intravascularly.

Sedation Weaning Initiative Targeting Methadone Exposure: Single Center Improvements in Withdrawal Symptoms and Hospital Length of Stay for Pediatric Cardiac Critical Care.

OBJECTIVES: Sedation and pain medications are necessary in the management of postoperative pediatric cardiac patients. Prolonged exposure to these medications can lead to negative side effects including withdrawal. We hypothesized that standardized weaning guidelines would decrease exposure to sedation medications and decrease withdrawal symptoms. The primary aim was to decrease average days of methadone exposure to within goal for moderate- and high-risk patients within 6 months. DESIGN: Quality improvement methods were used to standardize sedation medication weaning in a pediatric cardiac ICU. SETTING: This study took place at Duke Children's Hospital Pediatric Cardiac ICU in Durham, North Carolina from January 1, 2020, to December 31, 2021. PATIENTS: Children less than 12 months old admitted to the pediatric cardiac ICU who underwent cardiac surgery. INTERVENTIONS: Sedation weaning guidelines were implemented over the course of 12 months. Data were tracked every 6 months and compared with the 12 months pre-intervention. Patients were stratified into low, moderate, and high risk withdrawal categories based on duration of opioid infusion exposure. MEASUREMENTS AND MAIN RESULTS: Total sample size was 94 patients in the moderate and high risk categories. Process measures included documentation of Withdrawal Assessment Tool scores and appropriate methadone prescription in patients which increased to 100% post-intervention. For outcome measures, we observed decreased dexmedetomidine infusion duration, decreased methadone wean duration, decreased frequency of elevated Withdrawal Assessment Tool scores, and decreased hospital length of stay post-intervention. For the primary aim, methadone wean duration consistently decreased after each study period. Our intervention did not adversely impact balancing measures. CONCLUSIONS: A quality improvement initiative to standardize sedation weaning in a Pediatric Cardiac ICU was successfully implemented and was correlated with decreased duration of sedation medications, decreased withdrawal scores, and decreased length of stay.

Intravascular Gas Exchange: Physiology, Literature Review, and Current Efforts.

Acute respiratory failure with inadequate oxygenation and/or ventilation is a common reason for ICU admission in children and adults. Despite the morbidity and mortality associated with acute respiratory failure, few proven treatment options exist beyond invasive ventilation. Attempts to develop intravascular respiratory assist catheters capable of providing clinically important gas exchange have had limited success. Only one device, the IVOX catheter, was tested in human clinical trials before development was halted without FDA approval. Overcoming the technical challenges associated with providing safe and effective gas exchange within the confines of the intravascular space remains a daunting task for physicians and engineers. It requires a detailed understanding of the fundamentals of gas transport and respiratory physiology to optimize the design for a successful device. This article reviews the potential benefits of such respiratory assist catheters, considerations for device design, previous attempts at intravascular gas exchange, and the motivation for continued development efforts.

Standardized Training for Physicians Practicing Pediatric Cardiac Critical Care.

OBJECTIVES: In the vast majority of Children's Hospitals, the critically ill patient can be found in one of three locations: the PICU, the neonatal ICU, and the cardiac ICU. Training, certification, and maintenance of certification for neonatology and critical care medicine are over seen by the Accreditation Council for Graduate Medical Education and American Board of Pediatrics. There is no standardization of training or oversight of certification and maintenance of certification for pediatric cardiac critical care. DATA SOURCES: The curricula from the twenty 4th year pediatric cardiac critical care training programs were collated, along with the learning objectives from the Pediatric Cardiac Intensive Care Society published "Curriculum for Pediatric Cardiac Critical Care Medicine." STUDY SELECTION: This initiative is endorsed by the Pediatric Cardiac Intensive Care Society as a first step toward Accreditation Council for Graduate Medical Education oversight of training and American Board of Pediatrics oversight of maintenance of certification. DATA EXTRACTION: A taskforce was established of cardiac intensivists, including the directors of all 4th year pediatric cardiac critical care training programs. DATA SYNTHESIS: Using modified Delphi methodology, learning objectives, rotational requirements, and institutional requirements for providing training were developed. CONCLUSIONS: In the current era of increasing specialized care in pediatric cardiac critical care, standardized training for pediatric cardiac critical care is paramount to optimizing outcomes.

Development of a novel intravascular oxygenator catheter: Oxygen mass transfer properties across nonporous hollow fiber membranes.

Despite hypoxic respiratory failure representing a large portion of total hospitalizations and healthcare spending worldwide, therapeutic options beyond mechanical ventilation are limited. We demonstrate the technical feasibility of providing oxygen to a bulk medium, such as blood, via diffusion across nonporous hollow fiber membranes (HFMs) using hyperbaric oxygen. The oxygen transfer across Teflon® membranes was characterized at oxygen pressures up to 2 bars in both a stirred tank vessel (CSTR) and a tubular device mimicking intravenous application. Fluxes over 550 ml min-1 m-2 were observed in well-mixed systems, and just over 350 ml min-1 m-2 in flow through tubular systems. Oxygen flux was proportional to the oxygen partial pressure inside the HFM over the tested range and increased with mixing of the bulk liquid. Some bubbles were observed at the higher pressures (1.9 bar) and when bulk liquid dissolved oxygen concentrations were high. High-frequency ultrasound was applied to detect and count individual bubbles, but no increase from background levels was detected during lower pressure operation. A conceptual model of the oxygen transport was developed and validated. Model parametric sensitivity studies demonstrated that diffusion through the thin fiber walls was a significant resistance to mass transfer, and that promoting convection around the fibers should enable physiologically relevant oxygen supply. This study indicates that a device is within reach that is capable of delivering greater than 10% of a patient's basal oxygen needs in a configuration that readily fits intravascularly.

Implantation of a HeartMate 3 ventricular assist device in a 21-kg pediatric patient with Fontan failure.

AIMS: The HeartMate 3 (HM3) ventricular assist device (VAD) is gaining popularity in adults due to a favorable risk profile. However, reports of HM3 use in children are limited, potentially due to concerns with device size. MATERIALS AND METHODS: Here we report the successful use of an HM3-VAD as a bridge to transplantation in a 21 kg (BSA 0.84), an 8-year-old male child with Fontan failure on home inotropes. RESULTS: Urgent VAD implantation was performed. The standard adult sewing ring was used. The tricuspid valve and papillary muscles were completely excised from the ventricular cavity to prevent inflow obstruction. The pump was placed in the left pleural space. Outflow graft and driveline implantation were routine. VAD function appeared excellent with a reduction in Fontan pressures and improved kidney and liver function. Reoperation was required once to rule out tamponade and twice to evacuate a recurrent right hemothorax. The patient was discharged 3 months later in good condition and underwent successful heart transplantation 10 months after VAD placement. DISCUSSION: This report demonstrates the feasibility of HM3-VAD implantation in a 21-kg Fontan patient, suggesting HM3 size is not a prohibitive limitation at this weight.

Indications and Outcomes for Temporary Mechanical Circulatory Support in Pediatric Patients with Cardiac Failure.

Temporary continuous-flow ventricular assist devices (cfVAD) and extracorporeal membrane oxygenation (ECMO) are options for temporary mechanical circulatory support in pediatric patients. Despite the increase in temporary cfVAD use, the literature describing its use in pediatrics is limited. This was a single-center retrospective review of temporary cfVAD and a cohort of similar ECMO patients between January 1, 2011, and June 30, 2016, in patients <19 years of age. Thirteen patients underwent temporary cfVAD placement and 11 patients underwent ECMO cannulation for similar indications during the study period. Precannulation data were not statistically different, except for higher lactate and lower pH in the ECMO cohort. Median length of cfVAD support was 20 days (range 6-227), compared with 9 days (range 1-15) on ECMO. Primary outcome for cfVAD patients was one decannulated with recovery, six transplanted, and six died, compared with ECMO patients with five decannulated with recovery, three transplanted after conversion to durable VAD, and three died. No patients were transplanted directly from ECMO. This review provides new evidence that temporary cfVAD use can be used to support pediatric patients more than longer periods of time compared with ECMO, with transition to durable VAD and transplant.

Motivation for feedback-seeking among pediatric residents: a mixed methods study.

BACKGROUND: For effective self-directed life-long learning physicians need to engage in feedback-seeking, which means fostering such behavior during training. Self-determination theory (SDT) posits that intrinsic motivation is fostered when the environment optimizes the individual's experience of autonomy, relatedness, and competence. Educational settings meeting these psychological needs may foster intrinsic motivation in trainees, enhance their desire for feedback, and promote feedback-seeking. We sought to examine residents' feedback-seeking behaviors through the lens of SDT and explore the association with intrinsic motivation and career choice. METHODS: We used a mixed-methods approach with an explanatory sequential design. Residents participated in simulation training, completed an inventory of intrinsic motivation (IMI) and responded to sequential opportunities for performance feedback requiring different levels of effort. We compared IMI scores and career choice between groups with different effort. We interviewed high-effort feedback-seekers and conducted thematic analysis of interview data. RESULTS: Thirty-four of 35 residents completed the survey (97%). Of those completing the study, 12 engaged in low-effort feedback-seeking only, 10 indicated intent for high-effort feedback-seeking and 10 actually engaged in higher effort to get feedback. Groups did not differ in mean IMI scores. Among high-effort feedback-seekers more residents were interested in critical care-related fields compared to the other groups. We identified 5 themes around autonomy, relatedness, and competence clarifying residents' reasons for feedback-seeking. CONCLUSIONS: Our findings suggest that among residents, the relationship between motivation and feedback-seeking is complex and cannot be predicted by IMI score. Career plans and relationships with feedback providers impact feedback-seeking, which can inform educational interventions.

Useful but Different: Resident Physician Perceptions of Interprofessional Feedback.

UNLABELLED: Phenomenon: Based on recently formulated interprofessional core competencies, physicians are expected to incorporate feedback from other healthcare professionals. Based on social identity theory, physicians likely differentiate between feedback from members of their own profession and others. The current study examined residents' experiences with, and perceptions of, interprofessional feedback. APPROACH: In 2013, Anesthesia, Obstetrics-Gynecology, Pediatrics, and Psychiatry residents completed a survey including questions about frequency of feedback from different professionals and its perceived value (5-point scale). The authors performed an analysis of variance to examine interactions between residency program and profession of feedback provider. They conducted follow-up interviews with a subset of residents to explore reasons for residents' survey ratings. FINDINGS: Fifty-two percent (131/254) of residents completed the survey, and 15 participated in interviews. Eighty percent of residents reported receiving written feedback from physicians, 26% from nurses, and less than 10% from other professions. There was a significant interaction between residency program and feedback provider profession, F(21, 847) = 3.82, p < .001, and a significant main effect of feedback provider profession, F(7, 847) = 73.7, p < .001. On post hoc analyses, residents from all programs valued feedback from attending physicians higher than feedback from others, and anesthesia residents rated feedback from other professionals significantly lower than other residents. Ten major themes arose from qualitative data analysis, which revealed an overall positive attitude toward interprofessional feedback and clarified reasons behind residents' perceptions and identified barriers. Insights: Residents in our study reported limited exposure to interprofessional feedback and valued such feedback less than intraprofessional feedback. However, our data suggest opportunities exist for effective utilization of interprofessional feedback.

Pulmonary Artery Band Reduces Left Atrial Pressure in Dilated Cardiomyopathy.

We describe a case of pulmonary artery band placement in a 2-month-old infant with dilated cardiomyopathy and moderate mitral regurgitation in impending need of ventricular assist device. Despite minimal change in echocardiographic appearance, pulmonary artery band placement resulted in significantly reduced left atrial pressure and unchanged right atrial pressure. Improved cardiac output has enabled weaning from ventilator support and favorable somatic growth with enteral feeding. The patient has been stable on milrinone for 3 months, awaiting cardiac transplantation on a regular ward. This therapy represents a potential alternative in small children, who are deemed high-risk candidates for mechanical circulatory support.