Anesthesia and analgesia
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Anesthesia and analgesia · Jun 2004
Case ReportsUse of continuous paravertebral analgesia to facilitate neurologic assessment and enhance recovery after thoracoabdominal aortic aneurysm repair.
Neurologic assessment after thoracic aortic aneurysm repair is important for detecting and treating late onset paraplegia. Traditional methods of pain control, such as patient-controlled IV analgesia and epidural analgesia, may interfere with neurologic assessment. We present a case of a patient who received continuous thoracic paravertebral analgesia that provided excellent analgesia while preserving the ability to monitor neurologic function. ⋯ We provided postoperative continuous paravertebral analgesia in a patient after thoracoabdominal aneurysm repair requiring postoperative neurologic assessment. Paravertebral analgesia provides unilateral analgesia with fewer neurologic and hemodynamic side effects than central neuraxial blockade and should be considered for management of patients undergoing thoracic aortic aneurysm repair.
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Anesthesia and analgesia · Jun 2004
Comparative StudyA specific alteration in the electroretinogram of Drosophila melanogaster is induced by halothane and other volatile general anesthetics.
In higher organisms, physiological investigations have provided a valuable complement to assays of anesthetic effects on whole-animal behavior. However, although complex motor programs of Drosophila melanogaster have been used to identify genes that influence anesthesia, electrophysiological studies of anesthetic effects in this invertebrate have been limited. Here we show that the electroretinogram (ERG), the extracellular recording of light-evoked mass potentials from the surface of the eye, reveals a distinct effect of halothane, enflurane, isoflurane, and desflurane. Behaviorally relevant concentrations of these volatile anesthetics severely reduced the transient component of the ERG at lights-off. Other prominent ERG components, such as the photoreceptor potential and the lights-on transient, were not consistently affected by these drugs. Surprisingly, for most anesthetics, a diminished off-transient was obtained only with short light pulses. An identical effect was observed in the absence of anesthetic by depressing the function of Shaker potassium channels. The possibility that halothane acts in the visual circuit by closing potassium channels was examined with a simple genetic test; the results were consistent with the hypothesis but fell short of providing definitive support. Nevertheless, our studies establish the ERG as a useful tool both for examining the influence of volatile anesthetics on a simple circuit and for identifying genes that contribute to anesthetic sensitivity. ⋯ Electroretinography (ERG) provides a useful monitor of anesthetic effects on the fruit fly. The effects of volatile anesthetics on the ERG are recapitulated by inactivation of potassium channels.
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Anesthesia and analgesia · Jun 2004
Comparative StudyInsulin decreases isoflurane minimum alveolar anesthetic concentration in rats independently of an effect on the spinal cord.
The observation that insulin supplies an element of analgesia suggests that insulin administration might decrease the concentration of inhaled anesthetic required to produce MAC (the minimum alveolar anesthetic concentration required to eliminate movement in response to noxious stimulation in 50% of subjects). We hypothesized that insulin decreases MAC by directly affecting the nervous system, by decreasing blood glucose, or both. To test these hypotheses, we infused increasing doses of insulin either intrathecally or IV in rats anesthetized with isoflurane and determined the resulting MAC change (assessing forelimb and hindlimb movement separately). Infusion of insulin produced a dose-related decrease in MAC that did not differ among groups. That is, the IV and intrathecal infusions caused similar decreases in MAC at a given infusion rate. Blood glucose concentrations were larger in the rats given insulin with 5% dextrose. However, the percentage change in MAC determined from forelimb versus hindlimb movement did not differ. For a given insulin infusion rate, MAC changes and glucose levels did not correlate with each other, except, possibly, for the most rapid infusion rate, for which smaller glucose concentrations were associated with a marginally larger decrease in MAC. Intrathecal infusions of insulin did not produce spinal cord injury. In summary, we found that insulin decreases isoflurane MAC in a dose-related manner independently of its effects on the blood concentration of glucose. The sites at which insulin acts to decrease MAC appear to be supraspinal rather than spinal. The effect may be due to a capacity of insulin to produce analgesia through an action on one or more neurotransmitter receptors. ⋯ Intrathecal and IV insulin administration equally decrease isoflurane MAC in rats, regardless of the concentration of blood sugar. These findings indicate that although insulin decreases MAC, the decrease is not mediated by actions on the spinal cord.
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Anesthesia and analgesia · Jun 2004
Case ReportsSuperficial cervical plexus block for vocal cord surgery in an awake pediatric patient.
Medialization thyroplasty is a surgical procedure that decreases the incidence of dysphonia and dysphagia in patients who have vocal cord paralysis. We report a case of a pediatric patient who underwent this procedure with minimal sedation and bilateral superficial cervical plexus blockade. The use of a regional technique provided analgesia while allowing the patient to phonate at the request of the surgeon. ⋯ Medialization thyroplasty is a surgical procedure that decreases the incidence of dysphagia and dysphonia in patients with vocal cord paralysis. This procedure is best performed in a patient who maintains the ability to phonate. We report a case of medialization thyroplasty in a pediatric patient after bilateral superficial cervical plexus blocks with minimal sedation.
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Anesthesia and analgesia · Jun 2004
Case ReportsA severe complication after laser-induced damage to a transtracheal catheter during endoscopic laryngeal microsurgery.
Subcutaneous emphysema and pneumothorax is a rare and severe complication of percutaneous transtracheal jet ventilation, usually caused by obstruction of the upper airway or displacement of the tracheal catheter. Nevertheless, it is our preferred technique for endoscopic laryngeal laser surgery. We report a patient with acute subcutaneous emphysema and pneumothorax during laser surgery, caused by unobserved laser damage and discuss the associated risk factors. ⋯ The percutaneous transtracheal jet ventilation for elective laryngeal laser surgery reduces the risk of airway fires and gives a free endoscopic operative field. This case report suggests that, even when using a teflon catheter, laser-induced damage with severe complications might occur.