Alagille Syndrome and Repeat Oxygenator Failure during Cardiopulmonary Bypass: A Word of Caution.

Alagille syndrome is an autosomal dominant disorder that is caused by heterozygous mutation of JAG1 or NOTCH2 gene that impacts several multisystem organs including but may not be limited to the liver, heart, musculoskeletal, skin, and the eyes. The most common congenital heart defect associated with Alagille syndrome is multilevel right ventricular outflow tract obstruction with multiple central and peripheral branch pulmonary arterial stenoses occurring in up to two-thirds of these patients. We report two cases of Alagille syndrome who underwent extensive pulmonary arterial branch rehabilitation and experienced unusual oxygenator failure during cardiopulmonary bypass (CPB). We present lessons learned from these two cases and the changes that we implemented in our practice that facilitated smooth conduct of CPB in other cases that we performed subsequently.

Thromboelastography on-the-go: Evaluation of the TEG 6s device during ground and high-altitude Aeromedical Evacuation with extracorporeal life support.

BACKGROUND: Coagulation monitoring capabilities during transport are limited. Thromboelastography (TEG) is a whole-blood clotting test measuring clot formation, stabilization, and fibrinolysis and is traditionally performed in a laboratory. We evaluated a new point-of-care TEG analyzer, TEG 6s (Haemonetics, Braintree, MA), in a large animal model of combat-relevant trauma managed with extracorporeal life support during ground and high-altitude aeromedical evacuation. The objective was to compare TEG 6s used during transport versus the predicate device, TEG 5000, used in the laboratory. We hypothesized that TEG 6s would be comparable with TEG 5000 during dynamically changing transport conditions. METHODS: Thromboelastography parameters (R, K, angle, MA, LY30) derived by TEG 6s and TEG 5000 were compared during transport of 8 swine. TEG 6s was transported with animals during ground transport and flight. TEG 5000 was stationary in an adjacent building. TEG 6s activated clotting time (ACT) was compared with a Hemochron Junior ACT analyzer (Accriva Diagnostics, San Diego, CA). Statistics were performed using SAS 9.4 with Deming regressions, Spearman correlations, and average differences compared. RESULTS: Correlation between devices was stronger at sea-level (R, r = 0.7413; K, r = 0.7115; angle, r = 0.7192; MA, r = 0.8386; LY30, r = 0.9099) than during high-altitude transport (R, r = 0.4787; K, r = 0.4007; angle, r = 0.3706; MA, r = 0.6573; LY30, r = 0.8481). Method agreement was comparable during stationary operation (R, r = 0.7978; K, r = 0.7974; angle, r = 0.7574; MA, r = 0.7841; LY30, r = 0.9140) versus ground transport (R, r = 0.7927; K, r = 0.6246; angle, r = 0.6967; MA, r = 0.9163; LY30, r = 0.8603). TEG 6s ACT trended higher than Hemochron ACT when subjects were heparinized (average difference, 1,442 ± 1,703 seconds) without a methodological difference by Deming regression. CONCLUSION: Mobile TEG 6s during ground and altitude transport is feasible and provides unprecedented information to guide coagulation management. Future studies should assess the precision and accuracy of TEG 6s during transport of critically ill.

Automatic proximal airway volume segmentation using optical coherence tomography for assessment of inhalation injury.

BACKGROUND: Acute respiratory distress syndrome (ARDS) is a severe form of acute lung injury with a mortality rate of up to 40%. Early management of ARDS has been difficult due to the lack of sensitive imaging tools and robust analysis software. We previously designed an optical coherence tomography (OCT) system to evaluate mucosa thickness (MT) after smoke inhalation, but the analysis relied on manual segmentation. The aim of this study is to assess in vivo proximal airway volume (PAV) after inhalation injury using automated OCT segmentation and correlate the PAV to lung function for rapid indication of ARDS. METHODS: Anesthetized female Yorkshire pigs (n = 14) received smoke inhalation injury (SII) and 40% total body surface area thermal burns. Measurements of PaO2-to-FiO2 ratio (PFR), peak inspiratory pressure (PIP), dynamic compliance, airway resistance, and OCT bronchoscopy were performed at baseline, postinjury, 24 hours, 48 hours, 72 hours after injury. A tissue segmentation algorithm based on graph theory was used to reconstruct a three-dimensional (3D) model of lower respiratory tract and estimate PAV. Proximal airway volume was correlated with PFR, PIP, compliance, resistance, and MT measurement using a linear regression model. RESULTS: Proximal airway volume decreased after the SII: the group mean of proximal airway volume at baseline, postinjury, 24 hours, 48 hours, 72 hours were 20.86 cm (±1.39 cm), 17.61 cm (±0.99 cm), 14.83 cm (±1.20 cm), 14.88 cm (±1.21 cm), and 13.11 cm (±1.59 cm), respectively. The decrease in the PAV was more prominent in the animals that developed ARDS after 24 hours after the injury. PAV was significantly correlated with PIP (r = 0.48, p < 0.001), compliance (r = 0.55, p < 0.001), resistance (r = 0.35, p < 0.01), MT (r = 0.60, p < 0.001), and PFR (r = 0.34, p < 0.01). CONCLUSION: Optical coherence tomography is a useful tool to quantify changes in MT and PAV after SII and burns, which can be used as predictors of developing ARDS at an early stage. LEVEL OF EVIDENCE: Prognostic, level III.

Point-of-care endoscopic optical coherence tomography detects changes in mucosal thickness in ARDS due to smoke inhalation and burns.

BACKGROUND: The prevalence of acute respiratory distress syndrome (ARDS) in mechanically ventilated burn patients is 33%, with mortality varying from 11-46% depending on ARDS severity. Despite the new Berlin definition for ARDS, prompt bedside diagnosis is lacking. We developed and tested a bedside technique of fiberoptic-bronchoscopy-based optical coherence tomography (OCT) measurement of airway mucosal thickness (MT) for diagnosis of ARDS following smoke inhalation injury (SII) and burns. METHODS: 16 female Yorkshire pigs received SII and 40% thermal burns. OCT MT and PaO2-to-FiO2 ratio (PFR) measurements were taken at baseline, after injury, and at 24, 48, and 72h after injury. RESULTS: Injury led to thickening of MT which was sustained in animals that developed ARDS. Significant correlations were found between MT, PFR, peak inspiratory pressure (PIP), and total infused fluid volume. CONCLUSIONS: OCT is a useful tool to quantify MT changes in the airway following SII and burns. OCT may be effective as a diagnostic tool in the early stages of SII-induced ARDS and should be tested in humans.

Duplex Ultrasound Surveillance After Uncomplicated Endovascular Abdominal Aortic Aneurysm Repair.

OBJECTIVES: Health-care costs and risks of radiation and intravenous contrast exposure challenge computed tomography angiography (CTA) as the standard surveillance method after endovascular abdominal aortic aneurysm repair (EVAR). We reviewed our experience using Duplex ultrasound scan (DUS) as an initial and subsequent surveillance technique after uncomplicated EVAR. METHODS: The medical records of patients who underwent EVAR from 2004 to 2014 with at least 1 postoperative imaging study were retrospectively reviewed. Duplex ultrasound scan was the primary modality, with CTA reserved for patients with suspicious findings. RESULTS: Mean follow-up was 3.2 years for 266 patients. Fifty-seven endoleaks (7 type I, 50 type II) were detected in 51 patients (19%). Nineteen (33%) endoleaks were identified and monitored by DUS alone. Nine (16%) endoleaks were identified on CTA without prior DUS. Twenty-two (39%) endoleaks were identified on DUS and confirmed by CTA; 6 of these patients had a secondary intervention. When compared to subsequent CTA, there were 7 discordant results: 4 false-negative and 3 false-positive endoleaks on DUS. Two of these patients with discordant results required intervention. Follow-up CTA was not obtained for the other 2 patients due to severe comorbidities including renal disease. One of these patients eventually developed abdominal aortic aneurysm rupture and death. Among 88 patients with both DUS and CTA, positive predictive value and negative predictive value for DUS were 0.88 and 0.94, respectively. Sac size on DUS compared to CTA resulted in an interclass correlation coefficient of r = .84. CONCLUSIONS: In our experience, DUS was safe and effective for initial and follow-up surveillance after uncomplicated EVAR.