New-Onset Atrial Arrhythmias Are Independently Associated With In-Hospital Mortality in Veno-Venous Extracorporeal Membrane Oxygenation.

OBJECTIVE: To explore if atrial arrhythmias are associated with in-hospital mortality in veno-venous extracorporeal membrane oxygenation (VV-ECMO) patients. DESIGN: Retrospective observational cohort study. SETTING: Quaternary care academic medical center. PARTICIPANTS: Patients with respiratory failure requiring VV-ECMO for >24 hours between January 1, 2016, and January 1, 2019. INTERVENTIONS: None, observational study. MEASUREMENTS AND MAIN RESULTS: Two hundred nineteen VV-ECMO patients were included. Patients were stratified by absence or presence of clinically significant atrial arrhythmias during the VV-ECMO run. Atrial arrhythmias were defined as either atrial fibrillation or atrial flutter that occurred during VV-ECMO and required pharmacologic or electrical intervention. The primary outcome was in-hospital mortality. Secondary outcomes included a composite of thrombotic events, which included ischemic stroke and on-pump arterial thrombosis. Other objectives of this analysis included characterization of atrial arrhythmia incidence, risk factors, and management. A total of 67 patients (30.5%) experienced new-onset atrial arrhythmias post-ECMO cannulation. Age, male sex, and norepinephrine use were independently associated with atrial arrhythmia development. In-hospital mortality was significantly higher in the atrial arrhythmia group (38.8% v 19.1%; p = 0.003). In the multivariate logistic regression analysis, atrial arrhythmias during VV-ECMO were independently associated with increased odds of in-hospital mortality (odds ratio, 2.21; 95% confidence interval, 1.08-4.55; p = 0.03), after controlling for Respiratory Extracorporeal Membrane Oxygenation Survival Prediction score, acute renal failure, total norepinephrine dose, and total cannulation time. CONCLUSIONS: New-onset atrial arrhythmias are a frequent complication during VV-ECMO and are independently associated with excessive in-hospital mortality. Thus, their presence may serve as an important prognostic tool in this patient population.

An incidental finding of Dandy-Walker malformation.

ABSTRACT: Dandy-Walker malformation is a rare congenital anomaly affecting the posterior fossa, occurring in one in 30,000 births. Its hallmark characteristics include hypoplasia of the vermis, dilation of the fourth ventricle, and an enlarged posterior fossa. This case study describes a finding of Dandy-Walker malformation during a workup of encephalopathy in a patient on veno-venous extracorporeal membrane oxygenation for acute respiratory distress syndrome.

Pilot study evaluating a non-titrating, weight-based anticoagulation scheme for patients on veno-venous extracorporeal membrane oxygenation.

OBJECTIVE: There is no universally accepted algorithm for anticoagulation in patients on veno-venous extracorporeal membrane oxygenation. The purpose of this pilot study was to compare a non-titrating weight-based heparin infusion to that of a standard titration algorithm. METHODS: We performed a prospective randomized non-blinded study of patients: Arm 1-standard practice of titrating heparin to activated partial thromboplastin times goal of 45-55 seconds, and Arm 2-a non-titrating weight-based (10 units/kg/h) infusion. Primary outcome was need for oxygenator/circuit changes. Secondary outcomes included differences in hemolysis and bleeding episodes. Descriptive statistics were performed for the continuous data, and primary and secondary outcomes were compared using Fisher's exact test as appropriate. RESULTS: Six patients were randomized to Arm 1 and four to Arm 2. There was no difference in age, pH, PaO2/FiO2 ratio, peak inspiratory pressure, positive end expiratory pressure, mean airway pressure at time of cannulation, time on extracorporeal membrane oxygenation, or survival to hospital discharge in the two arms. Arm 1 had a statistically higher median activated partial thromboplastin times (48 (43, 52) vs 38 (35, 42), p < 0.008) and lower LDH (808 units/L (727, 1112) vs 940 units/L (809, 1137), p = 0.02) than Arm 2. There was no difference in plasma hemoglobin (4.3 (2.5, 8.7) vs 4.3 (3.0, 7.3), p = 0.65) between the two arms. There was no difference in mean oxygenator/circuit change, transfused packed red blood cell, or documented bleeding complications per patient in each arm (p = 0.56, 0.43, 0.77, respectively). CONCLUSION: In this pilot study, a non-titrating, weight-based heparin infusion appears safe and as effective in preventing veno-venous extracorporeal membrane oxygenation circuit thrombotic complications as compared to a titration algorithm. Larger studies are needed to confirm these preliminary findings.

Nitrogen Balance During Venovenous Extracorporeal Membrane Oxygenation Support: Preliminary Results of a Prospective, Observational Study.

BACKGROUND: Current literature is insufficient to support specific guidelines for estimating nutrition needs during extracorporeal membrane oxygenation (ECMO). The purpose of this single-center observational study was to investigate protein catabolism during venovenous (VV) ECMO support and assess whether current nutrition recommendations were adequate. METHODS: All patients admitted to the Lung Rescue Unit between November 2016 and June 2017 were screened for eligibility. Patients with a documented nitrogen balance (NB) study were included in the data set. NB results were excluded for a change in blood urea nitrogen ≥10 mg/dL during the urine collection or unquantified nitrogen losses. Demographics, ECMO-specific data, NB, nutrition prescription, and infusion were recorded in a prospective, observational manner. RESULTS: After exclusions, 25 NB results in 16 patients were included for analysis. Nonobese (body mass index [BMI] Ë‚ 30 kg/m2 ) and obese (BMI ≥ 30 kg/m2 ) patients received 85% and 84% of their prescribed protein, respectively. Nonobese patients had a mean NB of -1.7 ± 5.7, whereas obese patients had a mean NB of -11.5 ± 9.6. Obese patients displayed significantly higher urine urea nitrogen (26.7 ± 7.7 vs 13.5 ± 4.3; P = .00004). CONCLUSIONS: These preliminary findings suggest that current guidelines for estimating protein needs in critically ill patients may be adequate for nonobese patients receiving VV ECMO. However, current protein recommendations for critically ill obese patients may not be adequate during VV ECMO support, possibly related to significantly higher rates of catabolism. Future studies with a larger cohort of patients are needed to confirm these results.

Diel versus time-integrated (daily) photosynthesis and irradiance relationships of coral reef organisms and communities.

The most important source of energy to tropical shallow water coral reefs is light, the transformation of which ultimately limits reef biomass and growth. Therefore, measurements of productivity (primary production, P) for benthic reef organisms and communities are critical to understand reef functioning. Short-term (minutes to hours) P measurements of reef photosynthesizers virtually always produce the classic hyperbolic tangent (or similar) P-E (irradiance) relationship, with P rapidly rising to a saturation point as E increases. Longer-term (days to weeks), larger-scale investigations of natural reef communities typically do not explore P-E relationships, but the few that do show no saturation of time-integrated P with high time-integrated E. In this paper we present a modeling study to reconcile this apparent contradiction. We used 52 published short-term (instantaneous) P-E curves of organisms (corals, algae) and communities (corals, mixed corals and algae) from different reefs in the Indo-Pacific and the Caribbean, each coupled with 928 diel light curves comprising a wide range of cloud cover scenarios. The diel light curves provided instantaneous E at 1-minute intervals, from which we calculated corresponding instantaneous P using the different published P-E relationships. We integrated both variables to calculate time-integrated E and P. Time-integrated E varied up to 18-fold due to changes in cloud cover and season. We found that, despite routine saturation of instantaneous P, day-scale P-E relationships were near linear in all cases, with slightly decreased linearity in cases where instantaneous light saturation occurred very early during the day. This indicates that the Functional Convergence Hypothesis (FCH) developed by terrestrial ecologists may also apply for reef photosynthesizers. The FCH states that despite short-term light saturation, plants on average do not absorb more light than they can use, since resource allocations are strictly coordinated and tailored towards an optimal use. Thus, there is no contradiction: At the growth time scale (≥ day), P should be expected to be a near linear function of E. One implication is that reef P can be estimated using rapid optical measurements, as opposed to traditional, laborious respirometry methods. The requirement going forward is to derive appropriate values for light-use efficiency, which is the rate at which the plant or community converts absorbed light into fixed carbon.

Remote sensing of coral reefs and their physical environment.

There has been a vast improvement in access to remotely sensed data in just a few recent years. This revolution of information is the result of heavy investment in new technology by governments and industry, rapid developments in computing power and storage, and easy dissemination of data over the internet. Today, remotely sensed data are available to virtually anyone with a desktop computer. Here, we review the status of one of the most popular areas of marine remote sensing research: coral reefs. Previous reviews have focused on the ability of remote sensing to map the structure and habitat composition of coral reefs, but have neglected to consider the physical environment in which reefs occur. We provide a holistic review of what can, might, and cannot be mapped using remote sensing at this time. We cover aspects of reef structure and health but also discuss the diversity of physical environmental data such as temperature, winds, solar radiation and water quality. There have been numerous recent advances in the remote sensing of reefs and we hope that this paper enhances awareness of the diverse data sources available, and helps practitioners identify realistic objectives for remote sensing in coral reef areas.