Anesthesia and analgesia
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Anesthesia and analgesia · Apr 2002
Continuous three-in-one block for postoperative pain after lower limb orthopedic surgery: where do the catheters go?
Continuous three-in-one block is widely used for postoperative analgesia after proximal lower limb surgery, but location of the catheter has not been well addressed in the literature. We prospectively studied, in 100 patients, the characteristics of catheter threading under the iliac fascia and the correlations between catheter tip location and effective sensory and motor blockade of the three principal nerves of the lumbar plexus. Postoperatively, in conscious patients, 16 to 20 cm of a catheter was placed in the fascial sheath after femoral nerve location with a nerve stimulator. Contrast media (3 mL Iopamidol 390) was injected, and the catheter tip was located by means of an anteroposterior pelvic radiograph. An equal-volume mixture of 0.5% bupivacaine/2% lidocaine with epinephrine (30 mL) was injected through the catheter. Patient and catheter-insertion characteristics were noted. Thirty minutes after injection, sensory blockade was evaluated in the cutaneous territories of the lateral femoral cutaneous, femoral, and obturator nerves, along with motor blockade of the last two nerves. Pain scores at 30 min were also recorded. Seven block failures were noted. The tip of the catheter reached the lumbar plexus (Group 1) in 23% of the patients and lay deep to the medial (Group 2) or lateral (Group 3) part of the fascia iliaca in 33% and 37% of the patients, respectively. Demographic data and catheter threading characteristics were comparable among the groups. A three-in-one block was noted in 91% of Group 1 patients, but in only 52% and 27% of Group 2 and 3 patients, respectively (P < 0.05). Comparing Group 2 and 3 patients, sensory block was achieved in respectively 100% and 94% for the femoral nerve, 52% and 94% for the lateral femoral cutaneous nerve (P < 0.05), and 82% and 27% for the obturator nerve (P < 0.05). Visual analog scale pain scores on movement were significantly lower in Group 1 patients (P < 0.05). We conclude that during a continuous three-in-one block, the threaded catheter rarely reached the lumbar plexus. The quality of sensory and motor blockade and initial pain relief depend on the location of the catheter tip under the fascia iliaca. ⋯ The course of a continuous three-in-one block catheter is unpredictable. Only 23% of the catheters lie near the lumbar plexus. The success of sensory and motor blocks, as well as postoperative analgesia, depend on the position of the catheter under the fascia iliaca.
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Anesthesia and analgesia · Apr 2002
Clinical TrialRemifentanil in obstetric analgesia: a dose-finding study.
IV patient-controlled analgesia (PCA) with remifentanil is a new approach in systemic opioid analgesia during labor. We determined the minimum effective dose of IV remifentanil by increasing the PCA bolus from 0.2 microg/kg with 0.2 microg/kg increments during a 60-min study period until the analgesia was considered adequate by the parturient. Twenty healthy parturients with singleton pregnancies participated in the study during the first stage of labor. Remifentanil hydrochloride was given IV via PCA over 1 min with a lockout time of 1 min. The parturient started the PCA bolus at the first subjective sign of uterine contraction. All 17 patients who completed the study reached adequate pain relief. The median effective PCA bolus was 0.4 microg/kg and consumption was 0.066 microg x kg(-1) x min(-1), with wide individual variation (0.2-0.8 microg/kg and 0.027-0.207 microg x kg(-1) x min(-1), respectively). The pain scores were reduced by a median of 4.2 (25th-75th percentiles, 3.1-5.2; P < 0.001) on an 11-point numeric scale. Although there was a wide individual variation in the dose required, remifentanil seems effective for labor analgesia. However, maternal oxygen desaturation, sedation, and reduced fetal heart rate beat-to-beat variability were observed frequently. There was wide individual variation in the dose required for effective labor analgesia. Potentially serious side effects, which were observed frequently during remifentanil analgesia, may limit remifentanil's use in obstetrics. ⋯ We determined the minimum effective dose of patient-controlled IV remifentanil for labor analgesia. There was wide individual variation in the dose required for effective labor analgesia. Potentially serious side effects, which were observed frequently during remifentanil analgesia, may limit its use in obstetrics.
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Anesthesia and analgesia · Apr 2002
Case ReportsBlood patch therapy for spontaneous intracranial hypotension: safe performance after epidurography in an unconscious patient.
Epidurography was useful for identifying the epidural space and determining the likely spread of an epidural blood patch in an unconscious patient with spontaneous intracranial hypotension.
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Anesthesia and analgesia · Apr 2002
Case ReportsPossible bupivacaine toxicity after intraarticular injection for postarthroscopic analgesia of the knee: implications of the surgical procedure.
We report a case of possible bupivacaine toxicity after intraarticular injection during knee arthroscopy. The importance of the specific type of surgical procedure performed during arthroscopy and its relationship to potential local anesthetic toxicity are highlighted.
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Anesthesia and analgesia · Apr 2002
Spinal and peripheral mu opioids and the development of secondary tactile allodynia after thermal injury.
Local thermal injury to the paw leads to an increased sensitivity to a noxious stimulus applied to the site (primary thermal hyperalgesia) and an increased sensitivity to tactile stimuli in skin sites adjacent to the primary injury (secondary tactile allodynia; 2 degrees TA). We sought to define the peripheral and spinal actions of mu opioids in regulating 2 degrees TA. First, a mild thermal injury was induced on one heel, producing 2 degrees TA. This 2 degrees TA was blocked by pretreatment, but not posttreatment, with a topical mu-opioid agonist, loperamide (1.7%-5%). Second, 2 degrees TA was blocked by intrathecal morphine (0.1-10 microg) pre- and postinjury. 2 degrees TA reappeared when systemic naloxone was given before, but not after, injury in intrathecal morphine-pretreated rats. Intrathecal remifentanil, a short-lasting mu-opioid agonist, infused periinjury (3 microg/min), did not block subsequent primary thermal hyperalgesia, but it produced a dose-dependent (0.3-3 microg/min) abolition of 2 degrees TA. Local tissue injury leads to 2 degrees TA by the activation of opiate-sensitive afferents and the initiation of a cascade that persists in the absence of that initiating injury-induced stimulus. ⋯ Sensitivity to touch observed in areas adjacent to injury is blocked by opioids applied before, but not after, injury. This suggests that injury-activated opioid-sensitive fibers are responsible for sensitization and reveals a cascade that is diminished by pretreatment but not posttreatment, providing a rationale for adequate analgesia before injury (surgery) has occurred.