Prediction of readiness to decannulation from venovenous extracorporeal membrane oxygenation.

OBJECTIVE: The criteria and process for liberation from extracorporeal membrane oxygenation in patients with severe acute respiratory distress syndrome are not standardized. The predictive accuracy of the oxygen challenge test as a diagnostic test in determining weaning and decannulation from venovenous extracorporeal membrane oxygenation was tested. DESIGN: A single-centre, retrospective, observational cohort study. SETTING: Tertiary referral severe respiratory failure centre in a university hospital in the United Kingdom. PATIENTS: 253 adults with severe acute respiratory distress syndrome requiring extracorporeal membrane oxygenation. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: Patients had median age: 43 years (interquartile range: 32-52) years, extracorporeal membrane oxygenation days: 9 (interquartile range: 6-14) and acute physiology and chronic health evaluation II score 17.5 (interquartile range: 15-20). Oxygen challenge test value (PaO2-OCT) with best prediction was 31 kPa (232 mmHg; sensitivity 0.74; specificity 0.70; area under curve 0.77 (confidence interval: 0.73-0.81)). PaO2-OCT did not perform well as a prospective test to identify readiness to decannulation. Only 24 patients (10%) were decannulated 48 hours after their first positive oxygen challenge test (true positive) and 73.4% patients were false positives (positive oxygen challenge test but not decannulated). True positives had higher tidal volume (541 ± 218 vs 368 mL ± 210; p < 0.05) and minute ventilation (9.34 ± 5.36 vs 6.33 L/min ± 4.43; p < 0.05). Blood flow (3.17 ± 0.23 vs 3.53 L/min ± 0.56; p < 0.05), sweep gas flow (1.42 ±1.83 vs 3.74 L/min ± 2.43; p < 0.05) and extracorporeal membrane oxygenation minute volume at time of first positive oxygen challenge test was lower in true positives (1.66 ± 2.26 vs 4.82 ± 3.43 L/min). This was a strong predictor for decannulation within 48 hours (area under curve: 0.88, confidence interval: 0.88-0.89). CONCLUSIONS: In severe acute respiratory distress syndrome requiring venovenous extracorporeal membrane oxygenation, the PaO2-OCT is a poor predictor of readiness to decannulate from extracorporeal membrane oxygenation. Additional factors involved in the control of respiratory drive and carbon dioxide clearance, particularly native lung dead space and total minute ventilation, should be assessed.

Screening pulmonary angiogram and the effect on anticoagulation strategies in severe respiratory failure patients on venovenous extracorporeal membrane oxygenation.

BACKGROUND: Venovenous extracorporeal membrane oxygenation in the treatment of severe respiratory failure in adults continues to increase with survival improving; however, it remains associated with serious complications. OBJECTIVE: The aim of this study was to evaluate the prevalence of pulmonary embolism (PE) in patients with severe respiratory failure requiring venovenous extracorporeal membrane oxygenation (VV ECMO) and in those managed with conventional mechanical ventilation. METHODS: A single-center, observational cohort, retrospective study was undertaken of patients with severe respiratory failure managed with conventional ventilation or requiring ECMO in a tertiary referral university teaching hospital. RESULTS: We identified 343 patients with severe respiratory failure between January 2014 and December 2017. VV ECMO was used to support 290 patients and 53 were managed by conventional mechanical ventilation. The prevalence of PE was 9.6% (33/343), of which those supported with VV ECMO was 10% (29/290) and conventional ventilation 7.5% (4/53). There was no difference in survival rates between cohorts with PE versus no PE (ECMO survival to discharge P = .56; conventional ventilation survival to discharge P = .21). CONCLUSIONS: The prevalence of pulmonary embolism in severe respiratory failure has important clinical implications for both short and long-term anticoagulation strategies. Routine screening pulmonary angiogram is warranted in this cohort.

Rocuronium Versus Suxamethonium: A Survey of First-line Muscle Relaxant Use in UK Prehospital Rapid Sequence Induction.

INTRODUCTION: Prehospital anaesthesia in the United Kingdom (UK) is provided by Helicopter Emergency Medical Service (HEMS) and British Association for Immediate Care (BASICS), a road-based service. Muscle relaxation in rapid sequence induction (RSI) has been traditionally undertaken with the use of suxamethonium; however, rocuronium at higher doses has comparable intubating conditions with fewer side effects. HYPOTHESIS/PROBLEM: The aim of this survey was to establish how many prehospital services in the UK are now using rocuronium as first line in RSI. METHODS: An online survey was constructed identifying choice of first-line muscle relaxant for RSI and emailed to lead clinicians for BASICS and HEMS services across the UK. If rocuronium was used, further questions regarding optimal dose, sugammadex, contraindications, and difference in intubating conditions were asked. RESULTS: A total of 29 full responses (93.5%) were obtained from 31 services contacted. Suxamethonium was used first line by 17 prehospital services (58.6%) and rocuronium by 12 (41.4%). In 11 services (91.7%), a dose of 1 mg/kg of rocuronium was used, and in one service, 1.2 mg/kg (8.3%) was used. No services using rocuronium carried sugammadex. In five services, slower relaxation time was found using rocuronium (41.7%), and in seven services, no difference in intubation conditions were noted (58.3%). Contraindications to rocuronium use included high probability of difficult airway and anaphylaxis. CONCLUSION: Use of rocuronium as first-line muscle relaxant in prehospital RSI is increasing. Continued auditing of practice will ascertain which services have adopted change and identify if complications of failed intubation increase as a result.

Effects of distraction on visual enumeration in children and adults.

Speeded enumeration of visual stimuli typically produces a bilinear function, with a shallow subitizing rate (<100 ms/item) up to 3-4 items (subitizing span) and a steeper counting rate (~300 ms/item) thereafter. FINST theory (L. M. Trick & Z. W. Pylyshyn, 1993, 1994) suggests that subitizing of targets is possible in the presence of distractors if attention is not required for target detection, but this has not been tested in children. The present study explored enumeration without distractors (Os alone) and with distractors (Os among Xs) in 35 children aged 6-11 years and 17 adults. Subitizing span increased significantly from childhood to adulthood, and counting rate increased significantly with age. Bilinear functions were significantly better than linear fits to the data for most children and adults both without distractors (97% and 100%, respectively) and with distractors (89% and 94%), consistent with their efficient visual search for a single O among multiple Xs. These findings are discussed in comparison with those from new modeling of earlier enumeration data from young and older adults, revealing striking asymmetries in subitizing with distractors between development and aging.

How to survive an 11-storey fall.

Survival from a high fall is rarely possible. We report an unusual case of a patient who fell over 100 ft on to boggy ground and survived. A successful outcome was achieved by the use of aggressive blood product resuscitation and the early application of a pelvic fixator.