Anesthesia and analgesia
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Anesthesia and analgesia · May 1998
Randomized Controlled Trial Clinical TrialThe optimal test dose of epinephrine for epidural injection with lidocaine solution in awake patients premedicated with oral clonidine.
We attempted to determine the optimal test dose of epinephrine for use with epidural anesthesia in awake patients premedicated with clonidine. Eighty-eight adult patients were randomized into two groups [oral premedication with clonidine 5 microg/kg (CLON) or no premedication (CONT)]. Before induction of general anesthesia, heart rate (HR) and blood pressure (BP) were measured for 3 min after the i.v. injection of 3 mL of 1.5% lidocaine containing epinephrine (0, 1.25, 2.5, 5, 7.5, or 15 microg) in a randomized, double-blind manner. We calculated 95% confidence intervals for the peak HR and BP increases induced by each dose of epinephrine. At 7.5 microg, epinephrine induced a significantly greater increase in HR and BP in CLON than in CONT. The 95% confidence interval for the HR change induced by 7.5 microg of epinephrine in CLON was nearly the same as the accepted standard dose of epinephrine (15 microg) in CONT. We conclude that premedication with clonidine enhances HR and BP responses to the i.v. administration of epinephrine-containing epidural test solutions. Consequently, 7.5 microg of epinephrine may be sufficient to enable detection of accidental injection into a blood vessel in awake patients premedicated with clonidine 5 microg/kg. ⋯ Clonidine, a commonly used preanesthetic medication, alters patients' cardiovascular responses to drugs such as epinephrine. Our randomized, double-blind study suggests that, in awake patients receiving oral clonidine premedication, 7.5 microg of epinephrine (half the usual dose) is adequate as an indicator of accidental injection into the epidural vessels during epidural anesthesia.
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Anesthesia and analgesia · May 1998
Awareness with recall during general anesthesia: incidence and risk factors.
We studied the associated factors and incidence of awareness during general anesthesia and the nature of subsequent psychiatric disorders. Patients older than 12 yr undergoing surgery under general anesthesia in a secondary care hospital during 1 yr were included in the study. The doses of anesthetics were calculated for the patients with and without awareness. There were 4818 operations under general anesthesia; 2612 (54%) patients were interviewed. Ten (0.4% of those interviewed) patients were found to have undisputed awareness, and there were nine (0.3%) patients with possible awareness. The doses of isoflurane (P < 0.01) and propofol (P < 0.05) were smaller in patients with awareness. Five patients with awareness underwent a psychiatric evaluation. One patient experienced sleep disturbances afterward, but the other four patients did not have any after effects. In conclusion, awareness is a rare complication of general anesthesia associated with small doses of anesthetics. ⋯ In an interview of 2612 patients after general anesthesia, 10 (0.4%) patients with awareness and 9 (0.3%) patients with possible awareness were found. A predisposing factor was small doses of the principal anesthetic. In a psychiatric interview, a large proportion of the patients with awareness were found to have suffered from depression in the past.
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Anesthesia and analgesia · May 1998
Comparative StudyComparison of the three-in-one and fascia iliaca compartment blocks in adults: clinical and radiographic analysis.
The 3-in-1 (Group 1) and fascia iliaca compartment (Group 2) blocks, two single-injection, anterior approach procedures used to simultaneously block the femoral, obturator, and lateral femoral cutaneous (LFC) nerves, were compared in 100 adults after lower limb surgery. Pain control, sensory and motor blockades, and radiographically visualized spread of local anesthetic solution were studied prospectively. Both approaches provided efficient pain control using 30 mL of 2% lidocaine with 1:200,000 epinephrine and 0.5% bupivacaine and 5 mL of contrast media (iopamidol). Complete lumbar plexus blockade was achieved in 18 (38%) Group 1 and 17 (34%) Group 2 patients (n = 50 patients per group). Sensory block of the femoral, obturator, genitofemoral, and LFC nerves was obtained in 90% and 88%, 52% and 38%, 38% and 34%, and 62% and 90% of the patients in Groups 1 and 2, respectively (P < 0.05). Sensory LFC blockade was obtained more rapidly for the patients in Group 2 (P < 0.05). Concurrent internal and external spread of the local anesthetic solution under the fascia iliaca and between the iliacus and psoas muscles was noted in 62 of the 92 block procedures analyzed radiographically. Isolated external spreads under the fascia iliaca and over the iliacus muscle were noted in 10% and 36% of the patients in Groups 1 and 2, respectively (P < 0.05). The local anesthetic solution reached the lumbar plexus in only five radiographs. We conclude that the fascia iliaca compartment block is more effective than the 3-in-1 block in producing simultaneous blockade of the LFC and femoral nerves in adults. After both procedures, blockade was obtained primarily by the spread of local anesthetic under the fascia iliaca and only rarely by contact with the lumbar plexus. ⋯ In adults, the two anterior approaches, 3-in-1 and fascia iliaca compartment blocks, provide effective postoperative analgesia. The fascia iliaca compartment technique provides faster and more consistent simultaneous blockade of the lateral femoral cutaneous and femoral nerves. Sensory block is caused by the spread of local anesthetic solution under the fascia iliaca and only rarely to the lumbar plexus.
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Anesthesia and analgesia · May 1998
Randomized Controlled Trial Clinical TrialSimulation of an epidural test dose with intravenous epinephrine in sevoflurane-anesthetized children.
An epidural test dose containing small doses of epinephrine does not produce a reliable increase in heart rate (HR) in children under halothane anesthesia. Because sevoflurane is increasingly used in clinical practice, we designed the present study to determine the hemodynamic responses to, and efficacy of, a simulated IV test dose containing a small dose of epinephrine in sevoflurane-anesthetized children. Sixty ASA physical status I infants and children (4.1 +/- 2.5 yr) undergoing elective minor surgeries were studied during 1.0 minimum alveolar anesthetic concentration of sevoflurane and 60% nitrous oxide in oxygen. The patients were randomly assigned to receive either saline (n = 15), a test dose consisting of 1% lidocaine (0.1 mL/kg) with 1:200,000 epinephrine (0.5 microg/kg, n = 15), atropine 0.01 mg/kg followed 5 min later by saline (n = 15), or atropine followed by the test dose (n = 15) via a peripheral vein to simulate intravascular injection of the epidural test dose. HR and systolic blood pressure were recorded every 15 and 30 s, respectively. The test dose increased the HR from 15 to 60 s and from 15 to 90 s without and with atropine, respectively. Mean maximum increases in HR were similar with and without atropine (21 +/- 8 and 22 +/- 6 bpm, respectively). Of 15 children, 7 and 5 developed HR changes < 20 bpm after the test dose with and without atropine, respectively, whereas all children who received saline had an increase in HR < 20 bpm. No dysrhythmia occurred during the study. Our results indicate that an epidural test dose containing epinephrine is unreliable based on the conventional HR criterion (positive if > or = 20 bpm increase), but reliable on the modified HR criterion (positive if > or = 10 bpm increase) in children anesthetized with sevoflurane. I.v. atropine before the test dose injection did not improve the efficacy based on the conventional HR criterion. Because test doses of epinephrine-containing solution are used to determine whether an epidural catheter is intravascular, it is important to define the optimal test dose under sevoflurane anesthesia. ⋯ We found that during sevoflurane anesthesia in children, a heart rate increase > or = 10 bpm and a systolic blood pressure increase > or = 15 mm Hg, when preceded by atropine, may be reliable indicators for detecting intravascular injection.
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Anesthesia and analgesia · May 1998
Randomized Controlled Trial Clinical TrialTracheal intubation with rocuronium using the "timing principle".
We compared the endotracheal intubating conditions after rocuronium, using the "timing principle," with those after succinylcholine. The timing principle entails administration of a single bolus dose of nondepolarizing muscle relaxant, followed by an induction drug at the onset of clinical weakness. Forty-five patients were randomly assigned to three groups. Patients allocated to Groups 1 and 2 received rocuronium 0.6 mg/kg. At the onset of clinical weakness (onset of ptosis), anesthesia was induced with thiopental 4-6 mg/kg; intubation was accomplished after 45 s in Group 1 and after 60 s in Group 2. Patients in Group 3 received vecuronium (0.01 mg/kg) 3 min before the administration of thiopental and succinylcholine 1.5 mg/kg, and their tracheas were intubated 60 s later by a blind anesthesiologist. Intubating conditions were assessed according to a grading scale and were either good (5 patients in Groups 1 and 2, 4 patients in Group 3) or excellent (10 patients in Groups 1 + 2, 11 patients in Group 3) in all patients. Patients were interviewed postoperatively, and all were satisfied with the induction of anesthesia. We conclude that rocuronium 0.6 mg/kg provides good to excellent intubating conditions 45 and 60 s after the induction of anesthesia using the timing principle. ⋯ We compared the ease with which a breathing tube could be placed in patients using three techniques. The standard technique (succinylcholine) was compared with two others in which a muscle-relaxing drug (rocuronium) was administered just before the anesthetic drug (so-called timing principle). No difference among the techniques was observed.