Clonidine is used for analgesia and sedation in paediatric anaesthesia, but there are no data on its sedative properties and side effects in critically ill children. We studied 30 ventilated children aged 10 yr and under to determine an effective i.v. dosing range and to assess its cardiovascular effects. Twenty non-paralysed, ventilated children were given a background infusion of midazolam 50 micrograms kg-1 h-1 combined with a variable clonidine infusion (0.1-2 micrograms kg-1 h-1) to maintain optimal sedation. The effects of clonidine 1 microgram kg-1 h-1 on cardiac index were measured in 10 postoperative cardiac patients using a reverse Fick method. Dose-dependent sedation was achievable (713 out of 861 h) without cardiovascular side effects, but an infusion limit of clonidine 1 microgram kg-1 h-1 was inadequate in two patients. An increased dose limit of 2 micrograms kg-1 h-1 combined with midazolam 50 micrograms kg-1 h-1 achieved satisfactory sedation scores for 602 out of a total of 672 h studied with no failures. Clonidine in combination with midazolam at 1 microgram kg-1 h-1 was not associated with significant changes in heart rate arterial pressure or cardiac index.
Sustained observations are required to determine the marine plastic debris mass balance and to support effective policy for planning remedial action. However, observations currently remain scarce at the global scale. A satellite remote sensing system could make a substantial contribution to tackling this problem. Here, we make initial steps towards the potential design of such a remote sensing system by: (1) identifying the properties of marine plastic debris amenable to remote sensing methods and (2) highlighting the oceanic processes relevant to scientific questions about marine plastic debris. Remote sensing approaches are reviewed and matched to the optical properties of marine plastic debris and the relevant spatio-temporal scales of observation to identify challenges and opportunities in the field. Finally, steps needed to develop marine plastic debris detection by remote sensing platforms are proposed in terms of fundamental science as well as linkages to ongoing planning for satellite systems with similar observation requirements.
There is a paucity of data in the published literature on the ecological and economic impacts of derelict fishing traps (DFTs) in coastal ecosystems. We synthesized results from seven NOAA-funded trap fisheries studies around the United States and determined that DFT-caused losses to habitat and harvestable annual catch are pervasive, persistent, and largely preventable. Based on this synthesis, we identified key gaps to fill in order to better manage and prevent DFTs. We conclude with suggestions for developing a U.S. DFT management strategy including: (1) targeting studies to estimate mortality of fishery stocks, (2) assessing the economic impacts of DFTs on fisheries, (3) collaborating with the fishing industry to develop solutions to ghost fishing, and (4) examining the regional context and challenges resulting in DFTs to find effective policy solutions to manage, reduce, and prevent gear loss.
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