Anesthesia and analgesia
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Assessment of diastolic function should be a component of a comprehensive perioperative transesophageal echocardiographic examination. Abnormal diastolic function exists in >50% of patients presenting for cardiac and high-risk noncardiac surgery, and has been shown to be an independent predictor of adverse postoperative outcome. Normalcy of systolic function in 50% of patients with congestive heart failure implicates diastolic dysfunction as the probable etiology. ⋯ The availability of more sophisticated Doppler techniques, e.g., Doppler tissue imaging and flow propagation velocity, makes it possible to interrogate left ventricular diastolic function with greater precision, analyze specific stages of diastole, and to differentiate abnormalities of relaxation from compliance. Additionally, various Doppler-derived ratios can be used to estimate left ventricular filling pressures. The varying hemodynamic environment of the operating room mandates modification of the diagnostic algorithms used for ambulatory cardiac patients when left ventricular diastolic function is evaluated with transesophageal echocardiography in anesthetized surgical patients.
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Anesthesia and analgesia · Sep 2011
Randomized Controlled TrialThe effect of altering skin-surface cooling speeds on vasoconstriction and shivering thresholds.
Both core and skin temperatures contribute to steady-state thermoregulatory control. Dynamic thermoregulatory responses trigger aggressive defenses against rapid thermal perturbations. These responses potentially complicate interpretation of thermoregulatory studies and could slow induction of therapeutic hypothermia. We thus tested the hypothesis that rapid external skin-cooling triggers vasoconstriction and shivering at higher mean skin temperatures than slow or moderate rates of skin cooling. ⋯ Onset of vasoconstriction and shivering occurred at similar mean skin temperatures with all 3 cooling rates. Aggressive surface cooling can thus be used in thermoregulatory studies and for induction of therapeutic hypothermia without provoking dynamic thermoregulatory defenses.
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Anesthesia and analgesia · Sep 2011
Comparative StudyThe ability of pulse pressure variations obtained with CNAP™ device to predict fluid responsiveness in the operating room.
Respiratory-induced pulse pressure variations obtained with an arterial line (ΔPP(ART)) indicate fluid responsiveness in mechanically ventilated patients. The Infinity® CNAP™ SmartPod® (Dräger Medical AG & Co. KG, Lübeck, Germany) provides noninvasive continuous beat-to-beat arterial blood pressure measurements and a near real-time pressure waveform. We hypothesized that respiratory-induced pulse pressure variations obtained with the CNAP system (ΔPP(CNAP)) predict fluid responsiveness as well as ΔPP(ART) predicts fluid responsiveness in mechanically ventilated patients during general anesthesia. ⋯ A value of ΔPP(CNAP) >11% has a sensitivity of at least 62% in predicting preload-dependent responders to VE in mechanically ventilated patients during general anesthesia.
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Anesthesia and analgesia · Sep 2011
Gamma-aminobutyric acid type A receptor β3 subunit forebrain-specific knockout mice are resistant to the amnestic effect of isoflurane.
β3 containing γ-aminobutyric acid type A receptors (GABA(A)-Rs) mediate behavioral end points of IV anesthetics such as immobility and hypnosis. A knockout mouse with targeted forebrain deletion of the β3 subunit of the GABA(A)-R shows reduced sensitivity to the hypnotic effect of etomidate, as measured by the loss of righting reflex. The end points of amnesia and immobility produced by an inhaled anesthetic have yet to be evaluated in this conditional knockout. ⋯ These results suggest that β3 containing GABA(A)-Rs in the forebrain contribute to hippocampal-dependent memory suppressed by isoflurane, but not etomidate.
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Anesthesia and analgesia · Sep 2011
Reduction of spinal cord ischemia/reperfusion injury with simvastatin in rats.
Surgery of the thoracic or thoracoabdominal aorta may cause spinal cord ischemia and subsequent paraplegia. However, conventional strategies for preventing paraplegia due to spinal cord ischemia provide insufficient protection and cause additional side effects. We hypothesized that simvastatin, a drug recently shown to be neuroprotective against brain ischemia/reperfusion, would be neuroprotective in a rat spinal cord ischemia/reperfusion model. ⋯ Simvastatin treatment can attenuate hindlimb motor dysfunction and histopathological changes in spinal cord ischemia/reperfusion injury in rats.