Anesthesia and analgesia
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Anesthesia and analgesia · Jan 2004
Ventilation-perfusion distribution related to different inspiratory flow patterns in experimental lung injury.
In acute lung injury (ALI), controlled mechanical ventilation with decelerating inspiratory flow (.V(dec)) has been suggested to improve oxygenation when compared with constant flow (.V(con)) by improving the distribution of ventilation and perfusion (.V(A)/.Q). We performed the present study to test this hypothesis in an animal model of ALI. Furthermore, the effects of combined decelerating and constant flow (Vdot;(deco)) were evaluated. Thus, 18 pigs with experimental ALI were randomized to receive mechanical ventilation with either .V(con), .V(dec) or a fixed combination of both flow wave forms (.V(deco)) at the same tidal volume and positive end-expiratory pressure level for 6 h. Hemodynamics, gas exchange, and .V(A)/.Q distribution were determined. The results revealed an improvement of oxygenation resulting from a decrease of pulmonary shunt within each group (P < 0.05). However, blood flow to lung areas with a normal .V(A)/.Q distribution increased only during ventilation with .V(con) (P < 0.05). Accordingly, PaO(2) was higher with .V(con) than with .V(dec) and .V(deco) (P < 0.05). We conclude that contrary to the hypothesis, .V(con)provides a more favorable .V(A)/.Q distribution, and hence better oxygenation, when compared with .V(dec) and .V(deco) in this model of ALI. ⋯ In acute lung injury, mechanical ventilation with decelerating flow has been suggested to improve ventilation-perfusion distribution when compared with constant flow. We tested this hypothesis in an animal model. Contrary to the hypothesis, we found a more favorable ventilation-perfusion distribution during constant flow when compared with decelerating flow.
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Anesthesia and analgesia · Jan 2004
Reduction in [D-Ala2, NMePhe4, Gly-ol5]enkephalin-induced peripheral antinociception in diabetic rats: the role of the L-arginine/nitric oxide/cyclic guanosine monophosphate pathway.
To test our hypothesis that the abnormally small efficacy of mu-opioid agonists in diabetic rats may be due to functional changes in the L-arginine/nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway, we evaluated the effects of N-iminoethyl-L-ornithine, methylene blue, and 3-morpholino-sydnonimine on [D-Ala(2), NMePhe(4), Gly-ol(5)]enkephalin (DAMGO)-induced antinociception in both streptozotocin (STZ)-diabetic and nondiabetic rats. Animals were rendered diabetic by an injection of STZ (60 mg/kg intraperitoneally). Antinociception was evaluated by the formalin test. The mu-opioid receptor agonist DAMGO (1 microg per paw) suppressed the agitation response in the second phase. The antinociceptive effect of DAMGO in STZ-diabetic rats was significantly less than in nondiabetic rats. N-Iminoethyl-L-ornithine (100 microg per paw), an NO synthase inhibitor, or methylene blue (500 microg per paw), a guanylyl cyclase inhibitor, significantly decreased DAMGO-induced antinociception in both diabetic and nondiabetic rats. Furthermore, 3-morpholino-sydnonimine (200 microg per paw), an NO donor, enhanced the antinociceptive effect of DAMGO in nondiabetic rats but did not change in diabetic rats. These results suggest that the peripheral antinociceptive effect of DAMGO may result from activation of the L-arginine/NO/cGMP pathway and dysfunction of this pathway; also, events that are followed by cGMP activation may have contributed to the demonstrated poor antinociceptive response of diabetic rats to mu-opioid agonists. ⋯ This is the first study on the role of the nitric oxide (NO)/cyclic guanosine monophosphate pathway on [D-Ala(2), NMePhe(4), Gly-ol(5)]enkephalin (DAMGO)-induced peripheral antinociception and the effect of diabetes on this pathway. The study suggests a possible role of DAMGO as a peripherally-acting analgesic drug.
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Anesthesia and analgesia · Jan 2004
Comment Letter Comparative StudyDueling fiberoptic bronchoscope techniques.
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Anesthesia and analgesia · Jan 2004
Comment Letter Comparative StudyComparison between level 1 and rapid infusion system.