Anesthesia and analgesia
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Anesthesia and analgesia · Aug 2011
Randomized Controlled TrialMagnesium sulfate prevents remifentanil-induced postoperative hyperalgesia in patients undergoing thyroidectomy.
In a randomized, double-blind, prospective study, we investigated whether an intraoperative high versus low dose of remifentanil increased postoperative hyperalgesia and whether magnesium can prevent remifentanil-induced hyperalgesia. ⋯ A relatively high dose of intraoperative remifentanil enhances periincisional hyperalgesia. Intraoperative MgSO(4) prevents remifentanil-induced hyperalgesia. However, hyperalgesia did not reach clinical relevance in terms of postoperative pain or analgesic consumption in patients undergoing thyroidectomy.
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Anesthesia and analgesia · Aug 2011
ReviewThe clinical implications of isolated alpha(1) adrenergic stimulation.
Phenylephrine is a direct-acting, predominantly α(1) adrenergic receptor agonist used by anesthesiologists and intensivists to treat hypotension. A variety of physiologic studies suggest that α-agonists increase cardiac afterload, reduce venous compliance, and reduce renal bloodflow. The effects on gastrointestinal and cerebral perfusion are controversial. ⋯ Phenylephrine has been studied as an antihypotensive drug in patients with severe aortic stenosis, as a treatment for decompensated tetralogy of Fallot and hypoxemia during 1-lung ventilation, as well as for the treatment of septic shock, traumatic brain injury, vasospasm status-postsubarachnoid hemorrhage, and hypotension during cesarean delivery. In specific instances (critical aortic stenosis, tetralogy of Fallot, hypotension during cesarean delivery) in which the regional effects of phenylephrine (e.g., decreased heart rate, favorable alterations in Q(p):Q(s) ratio, improved fetal oxygen supply:demand ratio) outweigh its global effects (e.g., decreased cardiac output), phenylephrine may be a rational pharmacologic choice. In pathophysiologic states in which no regional advantages are gained by using an α(1) agonist, alternative vasopressors should be sought.
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Anesthesia and analgesia · Aug 2011
Randomized Controlled Trial Comparative StudyIntravenous sodium bicarbonate verifies intravenous position of catheters in ventilated patients.
Extravasation is the unintentional injection or leakage of fluids into the perivascular or subcutaneous space resulting in potential tissue injury. In this 2-part prospective, controlled study, we assessed the safety of subcutaneously injected sodium bicarbonate in rats first. In the second part, the diagnostic utility of using IV diluted sodium bicarbonate to confirm placement of IV catheters in endotracheally intubated and ventilated rats and patients was tested. Diluted sodium bicarbonate was created using undiluted standard 8.4% (1 mEq/mL) sodium bicarbonate mixed in a 1:1 ratio with sterile water to achieve a final diluted concentration of 4.2% (0.5 mEq/mL). ⋯ The injection of diluted sodium bicarbonate (in mechanically ventilated patients) can be used to reliably identify the correct location of an IV catheter by an increase in the exhaled carbon dioxide concentration. Although we found no skin damage with 4.2% (0.5 mEq/mL) sodium bicarbonate, safety and efficacy should be further evaluated in future studies.
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Anesthesia and analgesia · Aug 2011
Clinical TrialCardiac index in term pregnant women in the sitting, lateral, and supine positions: an observational, crossover study.
Aortocaval compression may affect maternal hemodynamic indices and fetal well-being in various maternal positions. There has been much debate regarding the optimal position for performing neuraxial blockade for labor analgesia and cesarean delivery. We hypothesized that in pregnant women at term, cardiac index (CI) may be improved in the lateral positions as compared with the flexed sitting position. Our primary outcome was to measure CI as assessed by suprasternal Doppler. ⋯ Positioning for neuraxial anesthesia may influence maternal hemodynamic variables. We found no difference in healthy fetal blood flow indices among positions, suggesting that these changes are not clinically significant. This study provides new physiological information on the changes that occur in a group in whom it has not been practical to study previously. Further study is necessary to determine whether these changes are significant in the presence of neuraxial anesthesia or in the high-risk parturient.
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Anesthesia and analgesia · Aug 2011
Comparative Study Clinical TrialTransient hemodynamic change and accuracy of arterial blood pressure-based cardiac output.
The purpose of this study was to determine the effects of transient arterial blood pressure change on the accuracy of the FloTrac™/Vigileo™ monitor (Edwards Lifesciences, Irvine, CA). ⋯ The FloTrac/Vigileo measured stroke volume with reasonable accuracy during transient hypotension but overestimated stroke volume during transient hypertension.