Anesthesiology
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Complex regional pain syndrome (CRPS) is a neuropathic pain disorder with significant autonomic features. Few treatments have proven effective, in part, because of a historically poor understanding of the mechanisms underlying the disorder. CRPS research largely conducted during the past decade has substantially increased knowledge regarding its pathophysiologic mechanisms, indicating that they are multifactorial. ⋯ These include peripheral and central sensitization, inflammation, altered sympathetic and catecholaminergic function, altered somatosensory representation in the brain, genetic factors, and psychophysiologic interactions. Relative contributions of the mechanisms underlying CRPS may differ across patients and even within a patient over time, particularly in the transition from "warm CRPS" (acute) to "cold CRPS" (chronic). Enhanced knowledge regarding the pathophysiology of CRPS increases the possibility of eventually achieving the goal of mechanism-based CRPS diagnosis and treatment.
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Randomized Controlled Trial Comparative Study
Cervical epidural pressure measurement: comparison in the prone and sitting positions.
The hanging drop technique is used for identifying the cervical epidural space, using its negative pressure. However, it is doubtful whether the epidural space intrinsically exhibits a negative pressure. We designed this study to test the hypothesis that the cervical epidural pressure (CEP) is significantly higher in the prone position than in the sitting position. To evaluate this hypothesis, we measured and compared 30 CEP values in the prone and sitting positions. ⋯ CEP was found to be significantly higher in the prone position than in the sitting position. Furthermore, CEPs were not consistently negative even in the sitting position. These results suggest that the hanging drop technique is inappropriate for identifying the cervical epidural space in either the prone or sitting positions. Clinical Trials Ref: NCT01009385.
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Randomized Controlled Trial Comparative Study
Effects of preoxygenation on desaturation time during hemorrhagic shock in pigs.
Patients in hemorrhagic shock often require emergent airway management. Clinical experience suggests that oxygen desaturation occurs rapidly in these patients; however, data are scant. The hypothesis of this study was that increasing levels of hemorrhagic shock, varying levels of fraction of inspired oxygen (Fio2) for preoxygenation, and fluid resuscitation significantly affect the duration until critical desaturation occurs. ⋯ Findings from this swine hemorrhagic shock model confirm that Fio2 and the level of hemorrhagic shock, but not fluid resuscitation, influence the rate of apneic desaturation. A five-fold increase in time until critical oxygen desaturation occurs can be achieved when preoxygenating with 100% oxygen compared with room air, underscoring the importance of adequate preoxygenation before emergent airway management.
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Randomized Controlled Trial Comparative Study
Fentanyl-sparing effect of acetaminophen as a mixture of fentanyl in intravenous parent-/nurse-controlled analgesia after pediatric ureteroneocystostomy.
Although acetaminophen has been used widely and is well tolerated in children, its efficacy and safety have not been clarified when combined with an opioid in intravenous parent-/nurse-controlled postoperative analgesia. ⋯ Acetaminophen has significant fentanyl-sparing effects and reduces side effects when combined with fentanyl in intravenous parent-/nurse-controlled analgesia for postoperative pediatric pain management.
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Meta Analysis Comparative Study
Variations in pharmacology of beta-blockers may contribute to heterogeneous results in trials of perioperative beta-blockade.
Randomized controlled trials and meta-analyses provide conflicting guidance on the role of beta-adrenergic receptor blockers (beta-blockers) in reducing perioperative complications. We hypothesize that variability in trial results may be due in part to heterogeneous properties of beta-blockers. First, we propose that the extent of beta-blocker metabolism by cytochrome P-450 and the time available to titrate the dosage before surgery (titration time) may interact; dependence on P-450 may be most harmful when titration time is short. Second, beta-blockers vary in their selectivity for the beta-1 receptor and reduced selectivity may contribute to cerebral ischemia. ⋯ Pharmacological properties of beta-blockers may contribute to heterogeneous trial results. Many trials have used metoprolol, which is extensively metabolized by cytochrome P450 and is less selective for the beta-1 receptor. For these two reasons, the efficacy of metoprolol to prevent perioperative cardiac complications should be compared with the efficacy of other beta-blockers.