Administration of 100% oxygen in diving accidents--an evaluation of four emergency oxygen devices.

As the use of oxygen enhances the resorption of gas bubbles in decompression illness, it is recommended and generally accepted that the inspired oxygen concentration in emergency treatment of diving accidents has to be as close to 100% as possible. Therefore, several emergency oxygen devices are offered to the diving community but only with little data in literature on the efficacy of these devices. We tested four emergency oxygen devices with respect to efficacy of oxygen supply and breathing comfort at rest. Nine blinded volunteers had to breathe from the four systems with face mask and mouthpiece as well. Gases were measured with mass spectrometry during a 3 min interval from a capillary port close to the subject. The results showed that none of the systems was able to deliver 100% oxygen all the time, but in three systems inspiratory oxygen values were achieved, although in one system the nitrogen wash-out was slowed due to air contamination during inspiration. The fourth tested system frequently supplied the subjects simply with air while breathing at rest. We conclude from our study that it is difficult to achieve oxygen levels close to 100% in practice. Even in a perfectly working system, the interface between device and subject is a source of entrained air, especially when oxygen breathing has to be performed over a longer period of time. In addition, two of four systems had conceptional problems to supply the subjects with pure O2 during inspiration. None of the tested systems was perfectly designed to serve in such emergencies.     

Motor performance is not related to injury risk in growing elite-level male youth football players. A causal inference approach to injury risk assessment

ObjectiveTo identify the causal relation between growth velocity and injury in elite-level youth football players, and to assess the mediating effects of motor performance in this causal pathway.DesignProspective cohort study.MethodsWe measured the body height of 378 male elite-level football players of the U13 to U15 age categories three to four months before and at the start of the competitive season. At the start of the season, players also performed a motor performance test battery, including motor coordination (Körperkoordinationstest für Kinder), muscular performance (standing broad jump, counter movement jump), flexibility (sit and reach), and endurance measures (YoYo intermittent recovery test). Injuries were continuously registered by the academies’ medical staff during the first two months of the season. Based on the causal directed acyclic graph (DAG) that identified our assumptions about causal relations between growth velocity (standardized to cm/y), injuries, and motor performance, the causal effect of growth velocity on injury was obtained by conditioning on maturity offset. We determined the natural indirect effects of growth velocity on injury mediated through motor performance.ResultsIn total, 105 players sustained an injury. Odds ratios (OR) showed a 15% increase in injury risk per centimetre/year of growth velocity (1.15, 95%CI: 1.05–1.26). There was no causal effect of growth on injury through the motor performance mediated pathways (all ORs were close to 1.0 with narrow 95%CIs).ConclusionsGrowth velocity is causally related to injury risk in elite-level youth football players, but motor performance does not mediate this relation.     

Retrograde approach for contralateral iliac and infrainguinal percutaneous transluminal angioplasty: experience in 100 patients.

To assess the technical feasibility of percutaneous transluminal angioplasty (PTA) performed by means of a retrograde contralateral approach, 201 PTA procedures performed from January 1989 to August 1990 were retrospectively reviewed. In 100 of these cases, the retrograde femoral artery puncture employed for acquisition of the initial diagnostic arteriogram was also used for angioplasty of 173 contralateral arteries. The overall technical success rate for PTA via the contralateral route was 91% (157 of 173 arteries). Overall success for contralateral suprainguinal disease was 94% (61 of 65) and was as follows for infrainguinal disease: femoral, 88% (68 of 77); popliteal, 90% (18 of 20); graft anastomoses, 100% (five of five); and infrapopliteal, 83% (five of six). There were eight procedure-related complications, including one clinically insignificant distal atheroembolization, two sheared balloon fragments, three arterial thromboses, and two postprocedural amputations. There were no puncture-related complications. PTA can be performed with a contralateral retrograde femoral puncture in a high percentage of patients, even when disease is well below the inguinal ligament.