Anesthesiology
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Recent clinical studies suggest that the magnitude of the second gas effect is considerably greater on arterial blood partial pressures of volatile agents than on end-expired partial pressures, and a significant second gas effect on blood partial pressures of oxygen and volatile agents occurs even at relatively low rates of nitrous oxide uptake. We set out to further investigate the mechanism of this phenomenon with the help of mathematical modeling. ⋯ Modeling of ventilation-perfusion inhomogeneity confirms that the second gas effect is greater in blood than in expired gas. Gas-based minimum alveolar concentration readings may therefore underestimate the depth of anesthesia during nitrous oxide anesthesia with volatile agents. The effect on minimum alveolar concentration is likely to be most pronounced for the less soluble volatile agents in current use.
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Polypharmacy is increasingly prevalent in older patients and is associated with adverse events among medical patients. The impact of polypharmacy on outcomes after elective surgery is poorly described. The authors' objective was to measure the association of polypharmacy with survival, complications, and resource use among older patients undergoing elective surgery. ⋯ Older patients with polypharmacy represent a high-risk stratum of the perioperative population. However, the authors' findings call into question the causality and generalizability of the polypharmacy-adverse outcome association that is well documented in nonsurgical patients.
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Ongoing neuropathic pain is difficult to treat. The authors examined whether dermorphin [D-Arg2, Lys4] (1-4) amide, a peripherally acting µ-opioid receptor agonist, attenuates ongoing pain-associated manifestations after nerve injury in rats and mice. ⋯ Peripherally acting μ-opioids may attenuate ongoing pain-related behavior and its neurophysiologic correlates. Yet, repeated administrations cause antiallodynic tolerance.