Anesthesia and analgesia
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Anesthesia and analgesia · May 2004
Comparative StudyA comparison of epinephrine and vasopressin in a porcine model of cardiac arrest after rapid intravenous injection of bupivacaine.
In a porcine model, we compared the efficacy of epinephrine, vasopressin, or the combination of epinephrine and vasopressin with that of saline placebo on the survival rate after bupivacaine-induced cardiac arrest. After the administration of 5 mg/kg of a 0.5% bupivacaine solution i.v., ventilation was interrupted for 3 +/- 1 min (mean +/- SD) until asystole occurred. Cardiopulmonary resuscitation (CPR) was initiated after 1 min of cardiac arrest. After 2 min of CPR, 28 animals received, every 5 min, epinephrine; vasopressin; epinephrine combined with vasopressin; or placebo i.v.. Three minutes after each drug administration, up to 3 countershocks (3, 4, and 6 J/kg) were administered; all subsequent shocks were 6 J/kg. Blood was drawn throughout the experiment for the determination of plasma bupivacaine concentration. In the vasopressin/epinephrine combination group, all pigs survived (P < 0.01 versus placebo); in the vasopressin group 5 of 7, in the epinephrine group 4 of 7, and in the placebo group none of 7 swine survived. The plasma concentration of total bupivacaine showed no significant difference among groups. In this model of bupivacaine-induced cardiac arrest, CPR with a combination of vasopressin and epinephrine resulted in significantly better survival rates than in the placebo group. ⋯ Although cardiovascular collapse occurs mostly immediately after rapid injection of a local anesthetic in the presence of anesthesiologists, resuscitation may be difficult, and the outcome is usually poor. In this model of bupivacaine-induced cardiac arrest, cardiopulmonary resuscitation with a combination of vasopressin and epinephrine resulted in significantly better survival rates than in the placebo group.
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Anesthesia and analgesia · May 2004
Case ReportsAnesthetic management of a patient in prone position with a drill bit penetrating the spinal canal at C1-C2, using a laryngeal mask.
Airway management in patients with penetrating neck trauma must guarantee cervical spine stability. Moreover, the prone position increases the risk of difficult ventilation and cervical spine injury. A 19-yr-old patient was brought to the emergency room in prone position with a drill bit protruding from the posterolateral aspect of his neck. The bit had entered the spinal canal below the first cervical vertebra, and placed near the odontoid peg. He was referred for surgical removal of the drill. The use of an inhaled induction of anesthesia, avoiding muscle relaxants, and ventilation through a laryngeal mask airway inserted in the prone position seemed to offer a satisfactory approach. ⋯ Management of patients with penetrating neck trauma must guarantee cervical spine stability. Moreover, the prone position increases the risk of difficult ventilation and cervical spine injury. Anesthesia may be induced and the airway can be managed with the patient already in the prone position for surgery.
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Anesthesia and analgesia · May 2004
Case ReportsTracheal ring fracture during a PercuTwist tracheostomy procedure.
Because of difficult weaning from mechanical ventilation, a 59-yr-old man admitted for emergency cardiac surgery underwent a bedside PercuTwist tracheostomy on day 14 of his intensive care unit stay. We observed a double fracture of the second tracheal ring during the initial dilation process with the PercuTwist dilator, associated with distal migration of a cartilage fragment, which was avulsed from the anterior portion of the second cartilaginous ring. ⋯ Like other antegrade single-step techniques, the PercuTwist tracheostomy presents the risk of anterior tracheal wall damage during the initial stage of the dilation process. Antegrade forces applied to the trachea should be minimized by sufficiently deep skin incision and both slow and smooth initial rotation of the dilator.
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Anesthesia and analgesia · May 2004
The relationship between bispectral index and electroencephalographic parameters during isoflurane anesthesia.
Bispectral index (BIS) integrates various electroencephalographic (EEG) parameters into a single variable. However, the exact algorithm used to synthesize the parameters to BIS values is not known. The relationship between BIS and EEG parameters was evaluated during nitrous oxide/isoflurane anesthesia. Twenty patients scheduled for elective ophthalmic surgery were enrolled in the study. After EEG recording with a BIS monitor (A-1050) was begun, general anesthesia was induced and maintained with 0.5%-2% isoflurane and 66% nitrous oxide. Using software we developed, we continuously recorded BIS, spectral edge frequency 95% (SEF95), and EEG parameters such as relative beta ratio (BetaRatio), relative synchrony of fast and slow wave (SynchFastSlow), and burst suppression ratio. BetaRatio was linearly correlated with BIS (r = 0.90; P < 0.01; n = 253) at BIS more than 60. At a BIS range of 30 to 80, SynchFastSlow (r = 0.60; P < 0.01; n = 3314) and SEF95 (r = 0.75; P < 0.01; n = 3339) were linearly correlated with BIS. The correlation between BIS and SEF95 was significantly better than the correlation between BIS and SynchFastSlow (P < 0.01). At BIS less than 30, the burst suppression ratio was inversely linearly correlated with BIS (r = 0.76; P < 0.01; n = 65). At BIS less than 80, burst-compensated SEF95 was linearly correlated with BIS (r = 0.78; P < 0.01; n = 3404). In the range of BIS from 60 to 100, BIS can be calculated from BetaRatio. At surgical levels of anesthesia, BIS and SynchFastSlow (a parameter derived from bispectral analysis) or burst-compensated SEF95 (derived from power spectral analysis) are well correlated. However, our results show that SynchFastSlow has no advantage over SEF95 in calculation of BIS. ⋯ The relationship between bispectral index (BIS) and electroencephalographic parameters was evaluated during nitrous oxide/isoflurane anesthesia. At surgical levels of anesthesia, BIS and the relative synchrony of fast and slow wave (a parameter derived from bispectral analysis) or burst-compensated spectral edge frequency 95% (a parameter derived from power spectral analysis) are well correlated.