Anesthesia and analgesia
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Anesthesia and analgesia · Aug 2003
Randomized Controlled Trial Comparative Study Clinical TrialA comparison of two regional anesthetic techniques for outpatient knee arthroscopy.
Small dose lidocaine spinal anesthesia and 3% 2-chloroprocaine epidural anesthesia provided comparable discharge times for outpatient knee arthroscopy. The incidence of transient neurologic symptoms with small-dose lidocaine spinal anesthesia was 12%.
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Anesthesia and analgesia · Aug 2003
Randomized Controlled Trial Clinical TrialThe effect of mixing lidocaine with propofol on the dose of propofol required for induction of anesthesia.
Lidocaine is used to reduce pain associated with propofol injection, either mixed with propofol or preceding it as a separate injection. The addition of lidocaine to propofol causes destabilization of the emulsion and reduces anesthetic potency in rats and humans. We conducted a randomized double-blinded study on 67 patients to assess the effect of mixing lidocaine with propofol on the dose of propofol required for the induction of anesthesia. Patients in Group S (n = 32) received IV lidocaine 0.2 mg/kg followed by an infusion of propofol whereas those in Group M (n = 35) received IV normal saline (placebo) followed by an infusion of a freshly prepared mixture of propofol 1%/lidocaine 1% in 10:1 volume ratio. The infusion was stopped when the subjects lost consciousness, as detected by the syringe-drop method. There was no statistically significant difference between the two groups in the mean (95% confidence interval) doses of propofol required for loss of consciousness: 2.0 (1.8-2.2) mg/kg for Group S versus 1.9 (1.7-2.0) mg/kg for Group M (P = 0.206). Mixing 20 mg of lidocaine with 200 mg of propofol is unlikely to affect the dose of propofol required for the induction of anesthesia. ⋯ Adding lidocaine to propofol destabilizes the propofol emulsion. A randomized double-blinded trial found no statistically significant difference in the doses of propofol required for the induction of anesthesia whether administered as a freshly prepared propofol 1%/lidocaine 1% 10:1 mixture or as a separate injection after a dose of lidocaine.
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Anesthesia and analgesia · Aug 2003
Randomized Controlled Trial Clinical TrialChoice of electrocardiography lead does not affect the usefulness of the T-wave criterion for detecting intravascular injection of an epinephrine test dose in anesthetized children.
Accidental intravascular injection of an epinephrine-containing test dose increases T-wave amplitude of lead II electrocardiogram (EKG) in anesthetized children. We designed this study to test whether the choice of EKG lead would affect the usefulness of simulated intravascular test dose. We studied 32 ASA physical status I infants and children (aged 6-49 mo) undergoing elective surgeries during 1.0 minimum alveolar anesthetic concentration sevoflurane and 67% nitrous oxide in oxygen. When hemodynamic stability was obtained, all subjects received IV saline 0.1 mL/kg, followed 4 min later by an IV test dose (0.1 mL/kg) consisting of 1% lidocaine with 1:200,000 epinephrine (epinephrine 0.5 microg/kg) via a peripheral vein to simulate the intravascular injection of the test dose. Heart rate and systolic blood pressure were recorded every 20 and 60 s, respectively, and leads II (n = 32), V(5) (n = 32) and either lead I (n = 15) or III (n = 17), choosing the one with greater preinjection T-wave amplitude, were continuously recorded for 4 min after the saline and the test dose injections. An IV test dose produced significant increases in heart rate, systolic blood pressure, and T-wave amplitude of all EKG leads studied in all subjects, whereas IV saline elicited no changes in these variables. Maximal increases in T-wave amplitude of leads II, I, III, and V(5) were 158% +/- 69%, 175% +/- 78%, 147% +/- 89%, and 170% +/- 72%, respectively (mean +/- SD, P > 0.05). There was no significant difference in temporal changes in T-wave amplitude among the 4 leads, and sensitivity and specificity were 100% on the basis of the T-wave criterion irrespective of the lead examined. Our results indicate that leads II, I, III, and V(5) of EKG are equally effective for detecting intravascular injection of the epinephrine-containing test dose in sevoflurane-anesthetized children. ⋯ To determine whether an epidurally administered local anesthetic has been accidentally injected into a blood vessel, a small dose of epinephrine is often added to a local anesthetic. We found that increases in T-wave amplitude in leads I, II, III, and V(5) of the electrocardiogram are equally sensitive and specific for detecting intravascular injection of the epinephrine-containing test dose in sevoflurane-anesthetized infants and children.
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Anesthesia and analgesia · Aug 2003
Randomized Controlled Trial Comparative Study Clinical TrialIntraocular pressure changes during laparoscopy in patients anesthetized with propofol total intravenous anesthesia versus isoflurane inhaled anesthesia.
We examined intraocular pressure (IOP) changes during gynecologic laparoscopy performed under either thiopental-isoflurane anesthesia or total IV propofol anesthesia. Forty adult women with no preexisting eye disease scheduled for gynecologic CO(2) insufflation laparoscopy were included in the study. Heart rate, mean arterial blood pressure, peak and plateau airway pressure, ETCO(2), and IOP (using a Schioetz tonometer) were measured at defined intervals during the procedure. IOP decreased significantly after the induction of anesthesia in both groups, and remained so throughout the procedure in the propofol group. In the isoflurane group, however, IOP was increased significantly above the preinduction level after pneumoperitoneum with head-down position. There was no correlation between IOP and blood pressure or airway pressure. In conclusion, propofol total IV anesthesia may be a better choice for laparoscopic surgery should control of IOP be a concern. ⋯ In this study, we examined the effect of two anesthetic techniques on the intraocular pressure changes during laparoscopic surgery in healthy subjects. Propofol IV anesthesia protected against increases in intraocular pressure with pneumoperitoneum and head-down position.
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Anesthesia and analgesia · Aug 2003
Comparative StudyA comparison of the neurotoxic effects on the spinal cord of tetracaine, lidocaine, bupivacaine, and ropivacaine administered intrathecally in rabbits.
We have reported that increased glutamate concentrations in microdialysate of the cerebrospinal fluid (CSF) may be clue phenomena to elucidate mechanisms of neurotoxicity of intrathecal tetracaine. However, little is known about whether this is true for other local anesthetics. In this study, we compared the effects of local anesthetics on glutamate concentrations in CSF microdialysate and neurologic and histopathologic outcome. Rabbits were assigned into 5 groups (n = 6 in each) and intrathecally received 0.3 mL of NaCl solution (control), 2% tetracaine, 10% lidocaine, 2% bupivacaine, or 2% ropivacaine. Neurologic and histopathologic assessments were performed 1 wk after the administration. Intrathecal local anesthetics significantly increased glutamate concentrations with no significant differences among the four local anesthetics. The sensory and motor functions in the lidocaine group were significantly worse than in the other groups. Characteristic histopathologic changes were vacuolation in the dorsal funiculus and chromatolytic damage of motor neurons. The extent of vacuolation of the dorsal funiculus was in the order of lidocaine = tetracaine > bupivacaine > ropivacaine. Although the differences among the local anesthetics cannot be explained by glutamate concentrations, the results suggest that the margin of safety may be smallest with lidocaine. ⋯ Large concentrations of local anesthetics administered intrathecally increased glutamate concentrations in the cerebrospinal fluid. The margin of safety may be smallest with lidocaine.