At this time, there is limited high-level evidence available for all of the NIRS devices on the market despite significant outcomes found in these studies. Additional prospective randomized studies should be conducted in order to establish the potential role NIRS may play in patient monitoring as well as assessing the efficacy of the multiple devices on the market.
1 The effects of levodopa alone (50mgkg-')and levodopa (10mgkg-1) plus benserazide (5Omgkg 1) were tested on the levels of dopa, dopamine, 3-methoxytyrosine (3-MT), 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA), measured by h.p.l.c. with electrochemical detection, in samples of plasma, CSF, urine, striatum and hypothalamus of rats taken 30min after injection. Levodopa plus benserazide produced significantly higher levels of dopa in plasma and brain than levodopa alone and reduced the peripheral synthesis and metabolism of dopamine. 2 When given chronically over 6 weeks the advantages of adding benserazide (50mg kg1 day 1) to levodopa (40 mg kg'-day -1) were less marked and although more dopamine was present in the striatum than with levodopa given alone (200 mg kg'-day-1) there was no evidence of any increase in its metabolites (HVA and DOPAC) and therefore of its turnover and utilisation. 3 The most striking effect of chronic treatment with levodopa plus benserazide was the appearance of large quantities of 3-MT in plasma, CSF and brain. 4 When levodopa alone, or levodopa plus benserazide, was given as an acute challenge to animals receiving the same treatment chronically, it was found that levodopa alone still produced increases in striatal dopamine, DOPAC and HVA in those animals dosed chronically on levodopa, but it was less effective in this respect when given with benserazide to the animals dosed with levadopa plus benserazide. 5 It is concluded that this difference in levodopa distribution may depend on the persistence in benserazide-treated animals of 3-MT, which has a long half-life and may compete with dopa for transport into the blood and brain. 6 The implication of these findings to the treatment of Parkinsonism is discussed.
Mitral valve surgery is often complicated by a postoperative low cardiac output state. In addition, some patients may have pre-existing pulmonary hypertension. Conventional inotropes, such as dopamine and dobutamine, tend to increase pulmonary vascular resistance. However, enoximone has both inotropic and vasodilatory properties. Ten patients, who had undergone mitral valve surgery and in whom weaning from cardiopulmonary bypass was unsuccessful without inotropic support, were treated with enoximone, 1 mg/ kg loading dose plus 10 µg/kg/min continuous infusion, to assist in weaning from bypass. A significant and sustained increase in cardiac index was achieved without an increase in heart rate. At the same time, mean arterial pressure, systemic vascular and pulmonary vascular resistances were significantly decreased.
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