Canadian journal of anaesthesia = Journal canadien d'anesthésie
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This study was designed to test the hypothesis that the alpha 2 adrenergic agonist, dexmedetomidine (DEX), decreases tissue oxygen demand thereby increasing tolerance to hypoxic insult. In 17 anaesthetized dogs, cardiac output was measured with thermodilution, blood flow through the inferior caval vein was determined using an electromagnetic flowmeter, and oxygen consumption was calculated by the Fick principle. The animals were divided into three groups: control group (n = 5), D3 and D30 groups (n = 6 for each group) treated with two doses of DEX (3 micrograms.kg-1 and 30 micrograms.kg-1, respectively) prior to aortic crossclamping. ⋯ Oxygen consumption in the upper part of the body decreased equally in all three groups. Arterial lactate concentrations increased almost two-fold in the control group while it increased by only 30% in animals treated with DEX. A lesser increase in lactate concentrations and oxygen extraction in tissues below aortic crossclamping is consistent with the hypothesis that DEX decreases tissue oxygen requirement which might prove particularly useful in clinical situations where tissue hypoxia is expected.
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Review Case Reports
Epidural anaesthesia for caesarean section in an achondroplastic dwarf.
This report describes the anaesthetic management of an 18-yr-old achondroplastic dwarf who presented for elective Caesarean section. Epidural anaesthesia was performed without technical difficulty using 8 ml carbonated lidocaine 2% with epinephrine 1:200,000. ⋯ Previous reports have described technical difficulties in these patients, such as dural puncture and inability to advance the catheter into the epidural space, but no serious complications resulted and epidural anaesthesia was successful on subsequent attempts. The existing literature on the anaesthetic management of achondroplasia for Caesarean section is reviewed and considerations are presented concerning the choice of local anaesthetic, the epidural test dose, and dose titration.
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The author presents and discusses the anaesthetic implications of a four-month-old infant with Menkes' syndrome who required tracheostomy. Menkes' syndrome is an X-linked recessive disorder of copper absorption and metabolism. Defective processing of copper results in abnormalities of several enzyme systems leading to severe dysfunction of multiple organ systems. ⋯ The high prevalence of seizure disorders, gastroesophageal reflux with the risk of aspiration, and airway complications related to poor pharyngeal muscle control are of concern to the anaesthetist. In addition, defective collagen formation, similar to that seen in Ehlers-Danlos syndrome, may be present. Identification of these associated conditions during the preoperative examination will guide the selection of appropriate, safe anaesthetic care for these children.
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Randomized Controlled Trial Clinical Trial
Axillary plexus block using a peripheral nerve stimulator: single or multiple injections.
This prospective, randomized, double-blind study was undertaken to evaluate the success rates of axillary brachial plexus block performed with the help of a peripheral nerve stimulator when either one, two or four of the major nerves of the brachial plexus were located. Seventy-five patients undergoing upper limb surgery were randomly allocated to one of the following five groups according to the nerve and number of nerves to be located; G-1: musculo-cutaneous, radial, median and ulnar nerves; G-2: musculo-cutaneous plus one of the other three nerves; G-3: radial nerve; G-4: median nerve; G-5: ulnar nerve. ⋯ Only one out of the 15 patients in G-1 and G-2 needed completion of their block before surgery whereas seven out of 15 for G-3 and eight out of 15 for G-4 and G-5 needed completion of their block (P less than 0.01). We conclude that when performing an axillary block with the help of a peripheral nerve stimulator, stimulation of the musculo-cutaneous nerve and one other nerve or stimulation of all four major nerves of the brachial plexus gives a higher success rate than stimulation of only one nerve, whether the stimulated nerve is the median, radial or ulnar.