Intubating Laryngeal Mask Airway for Difficult Airway / 대한마취과학회지

BACKGROUND: Almost all anesthesiologists are encounter a difficult airway occasionally, which is probably the most important cause of anesthesia related morbidity and mortality. The intubating laryngeal mask airway (ILMA; FastarachTM; laryngeal mask company, Henley-on-Thames, UK) is a new device for tracheal intubation. It is an ideal rescue airway since it can be placed quickly and used as a conduit for endotracheal intubation, while ventilation is ongoing. This prospective study was underttaken from January, 1997 to December, 2004 to evaluate the appropriateness of the ILMA for anticipated or unanticipated difficult airways. METHODS: After institutional committee approval, seventy eight patients were enrolled in this study. The anticipated group compromised thirty five patients and the unanticipated group forty three. In the unanticipated group, anesthesia was induced with thiopental sodium and vecuronium and maintained with enflurane or isoflurane, whereas in the anticipated group, awake intubation with nerve block was done before intubation. The success of the technique (within five attempts), the number of attempts, the durations of the successful attempts, and adverse events (desaturation, bleeding) were recorded. RESULTS: The rate of successful tracheal intubation with ILMA was 92.7%. The numbers of attempts and the times to success were not significantly different between the two groups. Adverse events occurred significantly more frequently in the unanticipated group. Conclusion: The ILMA is a useful device for the management of patients with a difficult airway and may be a valuable alternative to direct laryngoscopy or fiberoptic intubation when neck movement is unfavorable or in those with an unanticipated difficult airway.

Spinal Antinociceptive Mechanism of Isoflurane and Enflurane via the GABAA Receptor in Rats / 대한마취과학회지

Background: Several studies have suggested that the spinal cord may be an important site of anesthetic action and have established that general anesthetics potentiate the effects of GABA at the GABAA receptor. It was, therefore, hypothesized that the suppression of nocifensive movements during anesthesia is due to an enhancement of GABAA receptor-mediated transmission. Therefore, the aim of this study was to determine behaviorally whether intrathecal GABA, glycine, or opioid receptor antagonists may change the anesthetic effect of isoflurane and enflurane. Methods: The minimal alveolar concentration (MAC) of isoflurane and enflurane was determined in Sprague-Dawley rats, by the tail-clamp technique. First, MAC was determined and then concentration of each inhalation agent was increased by 0.2% from the sub-MAC level. Moving latencies were observed after the intrathecal administration of each receptor antagonist. Rectal temperature was measured and maintained at a steady level during the experiment. Results: The spinal antinociceptive effects of isoflurane and enflurane were significantly reversed by the GABAA receptor antagonist bicuculline and picrotoxin (P < 0.05). The rectal temperature was well maintained within the range of 37-39 degrees C. Conclusions: Our results suggest that the general anesthesia induced by isoflurane and enflurane, which are similar in terms of their action mechanism, is likely to be related to the spinal GABAA receptor system.

Effects of Desflurane and Isoflurane on Arterial Oxygenation and Hemodynamics during One-lung Ventilation / 대한마취과학회지

BACKGROUND: Potent inhalational agents are widely used for thoracic anesthesia. They have several desirable properties, including ease of administration, rapid onset and offset, and bronchodilation. One potential drawback is their ability to directly inhibit hypoxic pulmonary vasoconstriction. Desflurane does not directly inhibit hypoxic pulmonary asoconstriction in vivo, in contrast to isoflurane using the same animal model. In this study, we compared the effects of desflurane and isoflurane on arterial oxygenation and hemodynamics during one lung ventilation in a humans. METHODS: Thirty five patients scheduled for coronary artery bypass graft were randomly assigned to one of group D/I and I/D. Group D/I consisted of four steps. Hemodynamics and oxygenation parameters were checked in each step. Step 1 was checked when they received desflurane to an end tidal concentration of 6% in 93% oxygen from induction until the end of 30 min of two lung ventilation. Step 2 was checked at the end of 30 min after starting one lung ventilation. Step 3 was checked at the end of 30 min after receiving isoflurane to an end tidal concentration of 1.2% in 93% oxygen during one lung ventilation. Step 4 was checked at the end of 30 min after restarting two lung ventilation. Group I/D received the two anesthetic agents in reverse order. We used the simple cross-over design methodology for treatment and period effect. RESULTS: We found no significant difference in hemodynamic and oxygenation parameters between the two inhalational agents except for a significant increase in mean pulmonary arterial pressure and pulmonary capillary wedge pressure caused by desflurane. CONCLUSIONS: During one lung ventilation, the choice between desflurane and isoflurane does not significantly influence arterial oxygenation and shunt fraction but desflurane should be administered with great caution if it is used as an alternative anesthetic in patients with ischemic heart disease.

Fatal Pulmonary Hemorrhage after Reperfusion of a Grafted Liver: A case report / 대한마취과학회지

We report a case of fatal pulmonary hemorrhage developed after reperfusion of grafted liver during a living-related liver transplantation. A 53 year-old man who had hepatic encephalopathy grade 4 with fulminant hepatic failure was scheduled for a living-related liver transplantation. Preoperative evaluation showed fever, hypoxia, hypotension, pneumonia, and pulmonary edema. Cardiopulmonary stability was maintained with oxygen therapy and inotropic agents. During the anhepatic period, the patient's vital signs remained stable with inotropic agents except one episode of sudden hypotension presumably due to right heart strain. However, hypoxia, acidosis, and electrolyte imbalance were becoming worsen in spite of variable treatments for correction. Immediately after reperfusion, a sudden increase of central venous pressure and pulmonary artery pressure was noticed. evere bradyarrhythmia, hypotension, hemoptysis, hypoxia, and acidosis were followed by cardiac arrest. Cardiopulmonary resuscitation was not successful and the patient expired

The Antiallodynic Effect of Edrophonium and Neostigmine in a Neuropathic Pain Model / 대한마취과학회지

BACKGROUND: Peripheral nerve injury may produce a syndrome consisting of spontaneous pain, allodynia and hyperpathia. Cholinesterase inhibitors are known to have an antinociceptive effect in hot plate and tail flick tests and to be mediated by spinal muscarinic system. The purpose of the current study was to determine the effect of intrathecally (i.t.) administered edrophonium and neostigmine on the touch-evoked allodynia and to identify the antagonism of antiallodynia in a rat model of neuropathic pain. METHODS: Sprague Dawley rats were prepared with tight ligation of left L5/L6 spinal nerves with 6~0 black silk and chronic lumbar intrathecal catheters. After obtaining the baseline hindpaw withdrawal scores, edrophonium (3~100ug) or neostigmine (0.3~10ug) was administered intrathecally. Tactile allodynia was measured using von Frey filaments and allodynic threshold was calculated by updown method. Motor dysfunction was assessed by observing righting/stepping reflex responses and abnormal weight bearing. To examine the reversal of antiallod ynia, muscarinic receptor antagonist atropine (10ug) or nicotinic receptor antagonist mecamylamine (10ug) was injected intrathecally 5 min. prior to injection of edrophonium or neostigmine. RESULTS: I.t. edrophonium and i.t. neostigmine produced a dose dependent antagonism of allodynic state but had moderate to severe effect on motor weakness at doses of 3 and 10 g of neostigmine. Pretreatment with i.t. atropine yielded a complete antagonism of antiallodynia in both drugs, but i.t. mecamylamine did not significantly reverse incresed allodynic threshold. CONCLUSIONS: These experiments suggest that i.t. edrophonium or i.t. neostigmine produces a dose dependent antagonism on touch-evoked allodynia at the spinal level and this antagonism is likely due to spinal muscarinic system.