Anesthesiology
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Few studies have examined the possible adverse effects that epidural injection of depot corticosteroid preparations may have on meningeal membranes and nervous tissue. Thirty-six healthy adult white rabbits received 0.3 ml/kg epidural injections of either lactated Ringer's solution (negative control group), 1% lidocaine containing methylprednisolone acetate (study group), or normal saline containing talc (positive control group). Animals were killed either 4 or 10 days after injection and stained sections of the spinal cord and meningeal membranes were examined by light microscopy. ⋯ All animals that received epidural injections of normal saline containing talc had marked infiltration of tissue macrophages in the epidural space. There was no thickening of the meningeal membranes or nerve roots in any animal. The complete lack of inflammatory changes and meningeal thickening demonstrated in this pilot study helps to confirm the safety of methylprednisolone acetate when injected into the epidural space.
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The use of the laryngeal mask airway, a new form of airway, is described in infants and young children receiving radiotherapy under general anesthesia. The laryngeal mask airway consists of a tube, at the distal end of which is attached an elliptically shaped cuff resembling a miniature face mask. ⋯ No complications occurred during use of the laryngeal mask in 25 children who received 312 anesthetics. This experience suggests that the laryngeal mask airway has a valuable role in this situation and may contribute to the safety of anesthesia.
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Changes in oxygen consumption (VO2) and oxygen delivery (DO2) were compared in three groups of paralyzed, sedated dogs: 1) a group (n = 5) cooled to 29 degrees C and immediately rewarmed to 37 degrees C; 2) a group (n = 5) cooled to and maintained at 29 degrees C for 24 h, and then rewarmed; and 3) a group (n = 5) maintained at 37 degrees C for 24 h. During the cooling phase, in both the acute and prolonged hypothermia animals, VO2 and DO2 decreased significantly from control values (P less than 0.05). The decrease in DO2 occurred as a result of a similar decrease in cardiac index (CI; P less than 0.05) that was associated with a significant increase in systemic vascular resistance index (SVRI; P less than 0.05). ⋯ DO2 remained below control in both groups, resulting in a significant increase in O2 extraction (P less than 0.05) and a decrease in PVO2 (P less than 0.05) in the prolonged hypothermia animals. Following rewarming administration of sodium nitroprusside returned DO2, CI, and SVRI to control values but did not increase VO2. All animals survived the study without need for inotropic support.(ABSTRACT TRUNCATED AT 250 WORDS)
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To determine in infants and children the neuromuscular effect of pipecuronium during alfentanil-N2O/O2 anesthesia, the authors studied 32 ASA Physical Status 1 and 2 pediatric patients undergoing minor elective surgery, divided into three groups according to their age: group 1 included 12 infants, 1.9 +/- 0.2 months old (mean +/- SE; range, 20 days to 3 months), weighing 5.2 +/- 0.3 kg; group 2, 10 infants, 6.1 +/- 0.9 months old (range, 3-11 months), 6.9 +/- 0.4 kg; and group 3, 10 children 5.6 +/- 0.9 yr old (range, 2-9 yr), 19.6 +/- 2.2 kg. Neuromuscular blockade at the ulnar nerve-adductor pollicis muscle was measured by electromyography. Incremental iv doses of pipecuronium were given (one 20 micrograms/kg first dose, followed by 10 micrograms/kg increments) to reach a 95 +/- 2% twitch depression (ED95). ⋯ In 3- to 12-month-old infants ED50 and ED95 were 25.8 +/- 1.5 micrograms/kg and 48.7 +/- 3.5 micrograms/kg, respectively, and both significantly (P less than 0.05) less than those in children. In 0- to 3-month-old infants ED50 and ED95 were 23.7 +/- 1.7 micrograms/kg and 46.5 +/- 2.9 micrograms/kg, respectively, and also significantly (P less than 0.05) less than those measured in children. Time from maximal initial neuromuscular blockade to 75% recovery was 64.5 +/- 8.8 min in children and significantly shorter (P less than 0.05) in the two infant groups (0- to 3-month-old: 38.7 +/- 5.7 min, 3- to 12-month-old: 43.8 +/- 5.3 min, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)
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In patients undergoing neurosurgical procedures at high risk for venous air embolism (VAE), the presence of a right-to-left shunt adds an additional risk for paradoxical air embolism (PAE). Although this is a rare complication, it can have devastating results. The most common form of right-to-left shunt is a patient foramen ovale (PFO), which can be detected by contrast echocardiography. ⋯ Of these, four were detected by TEE. This is less than the expected incidence based on the known incidence of PFO in the general population. The usefulness of preoperative ECHO as a screening test for PFO in patients undergoing neurosurgical procedures is limited, but when a PFO is found, valuable information is acquired to help manage these patients.