Anesthesia and analgesia
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Anesthesia and analgesia · Jul 2010
Accuracy of methemoglobin detection by pulse CO-oximetry during hypoxia.
Methemoglobin in the blood cannot be detected by conventional pulse oximetry, although it can bias the oximeter's estimate (Spo2) of the true arterial functional oxygen saturation (Sao2). A recently introduced "Pulse CO-Oximeter" (Masimo Rainbow SET(R) Radical-7 Pulse CO-Oximeter, Masimo Corp., Irvine, CA) is intended to additionally monitor noninvasively the fractional carboxyhemoglobin and methemoglobin content in blood. The purpose of our study was to determine whether hypoxia affects the new device's estimated methemoglobin reading accuracy, and whether the presence of methemoglobin impairs the ability of the Radical-7 and a conventional pulse oximeter (Nonin 9700, Nonin Medical Inc., Plymouth, MN) to detect decreases in Sao2. ⋯ The Radical-7's methemoglobin readings become progressively more inaccurate as Sao2 decreases <95%, at times overestimating true values by 10% to 40%. Elevated methemoglobin causes the Spo2 readings to underestimate Sao2 similar to conventional 2-wavelength pulse oximeters at high saturation. Spo2 readings from both types of instruments continue to trend downward during the development of hypoxemia (Sao2 <90%) with methemoglobin levels up to 15%.
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Anesthesia and analgesia · Jul 2010
Skin collagen synthesis is depressed in patients with severe sepsis.
Skin is an essential barrier in maintaining a stable internal environment. Adequate regenerative capacity is crucial to overcome the homeostatic challenges caused by a septic insult. In sepsis, coagulation and inflammation are activated to restore homeostasis, but it is not known whether sepsis also alters tissue regeneration processes such as skin collagen synthesis. ⋯ Skin collagen synthesis is depressed during severe sepsis and is followed by a compensatory response 3 and 6 months after the onset of sepsis.
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Anesthesia and analgesia · Jul 2010
The relationship between functional sciatic nerve block duration and the rate of release of lidocaine from a controlled-release matrix.
Nerve blocks of long duration are often desirable in perioperative and postoperative situations. The relationship between the duration of such blocks and the rate at which a local anesthetic is released is important to know for developing a localized drug delivery system that will optimize block duration. ⋯ Increasing initial lidocaine content proportionately increased the duration of functional sciatic nerve block. However, decreasing the release rate per se does not give a proportional increase in block duration. Instead, there seems to be an optimal, intermediate release rate for achieving the maximum duration of block.
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Anesthesia and analgesia · Jul 2010
Activation of central opioid receptors induces cardioprotection against ischemia-reperfusion injury.
Small doses of intrathecal morphine provide cardioprotection similar to that conferred by IV morphine and ischemic preconditioning (IPC). We investigated the relative role of central versus peripheral opioid receptors in intrathecal morphine preconditioning (ITMPC). ⋯ Intrathecally administered morphine can produce cardioprotective effects via the activation of central opioid receptors, without the apparent involvement of peripheral opioid receptors.