Anesthesia and analgesia
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Anesthesia and analgesia · Oct 2001
Case ReportsThe long-term antinociceptive effect of intrathecal S(+)-ketamine in a patient with established morphine tolerance.
Our report describes for the first time the continuous long-term intrathecal application of S(+)-ketamine in a patient with chronic pain and morphine tolerance. Intrathecally applied S(+)-ketamine led to a significant pain reduction and consecutively reduced the doses of intrathecal morphine required for pain relief even several weeks after the cessation of the 24-day period of intrathecal S(+)-ketamine administration.
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Anesthesia and analgesia · Oct 2001
Clinical TrialThe pharmacokinetics of epidural ropivacaine in infants and young children.
The pharmacokinetic variables of ropivacaine were characterized after epidural bolus injection in pediatric patients. The subjects, 7 infants (aged 3-11 mo) and 11 young children (aged 12-48 mo), received 1.7 mg/kg of ropivacaine via a lumbar epidural catheter. Total plasma concentrations of ropivacaine measured over 24 h were assayed by high-pressure liquid chromatography, and pharmacokinetic modeling was performed by Nonlinear Mixed Effects Modeling analysis. The median peak venous plasma concentrations (C(max)) in infants and young children were 610 microg/L (interquartile range [IQR], 550-725 microg/L) and 640 microg/L (IQR, 540-750 microg/L), respectively. The median times to maximum plasma ropivacaine concentration (T(max)) were 60 min (IQR, 60-120 min) in infants and 60 min (IQR, 30-90 min) in young children. There were no statistical differences between median values of C(max) and T(max) between infants and young children. The calculated clearance (CL) in infants was 4.26 mL x min(-1) x kg(-1) (9% coefficient of variation), and in young children it was 6.15 mL x min(-1) x kg(-1) (11% coefficient of variation). The CL for infants was significantly less than the CL for young children (P < 0.01). The volume of distribution was estimated to be 2370 mL/kg (9% coefficient of variation) for both young children and infants. No systemic toxicity was observed in either group. ⋯ This study revealed that the pharmacokinetic variables of lumbar epidural bolus ropivacaine in pediatric patients aged 3 to 48 mo are similar to those of adults, except that drug clearance was less in infants compared with older children.
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Anesthesia and analgesia · Oct 2001
Clinical TrialThe optimal length of insertion of central venous catheters for pediatric patients.
Incorrect positioning of central venous catheters (CVC) in infants and children may lead to serious complications such as perforation of the heart or great vessels. CVC position is not usually assessed until the first postoperative chest radiograph, potentially leaving malposition undetected for several hours. We studied a series of 452 right internal jugular and subclavian catheter placements in infants and children undergoing surgery for congenital heart disease, and measured the distance from the skin insertion site to the radiographic junction of the superior vena cava and right atrium (RA). Based on these data, the following formulae predict that a CVC will be positioned above the RA 97% of the time: correct length of insertion (cm) = (height in cm/10) - 1 for patients < or =100 cm in height, and (height in cm/10) - 2 for patients >100 cm in height. Weight-based recommendations were also developed which predict placement of CVC above the RA 98% of the time. ⋯ This study assessed central venous catheter placement in 452 infants and children undergoing cardiac surgery. Simple, clinically useful guidelines based on height and weight were developed to prevent malposition of these catheters, which may cause serious complications such as perforation of the heart or great vessels.
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Anesthesia and analgesia · Oct 2001
Comparative StudyA prostaglandin E2 receptor subtype EP1 receptor antagonist (ONO-8711) reduces hyperalgesia, allodynia, and c-fos gene expression in rats with chronic nerve constriction.
Chronic constriction injury (CCI) of the sciatic nerve in rats induces persistent mechanical hyperalgesia and allodynia. CCI is widely known as a model of neuropathic pain, and many studies using this model have been reported. Recently, c-fos has been used as a neural marker of pain, and various studies have assessed the relationship between hyperalgesia and c-fos expression in the lumbar spinal cord. In this study, we examined the role of a prostaglandin E2 receptor subtype EP1 receptor antagonist (ONO-8711) in a rat CCI model. EP1 receptor antagonist (EP1-ra) oral administration from day 8 to day 14 significantly reduced hyperalgesia and allodynia in the three pain tests on day 15. EP1-ra treatment from day 8 to 14 also reduced c-fos-positive cells in laminae I-II, III-IV, and V-X compared with saline treatment. A single dose of EP1-ra treatment on day 8 significantly reduced hyperalgesia and allodynia at 1 h and 2 h after administration, but the efficacy was not observed at 24 h. We conclude that EP1-ra treatment may be useful for hyperalgesia and allodynia and that EP1 receptor mechanisms are involved in the maintenance of c-fos gene expression induced by nerve injury. ⋯ We examined whether a prostaglandin E2 receptor subtype EP1 receptor antagonist abrogates neuropathic pain induced by chronic constriction injury model in rats. The EP1 receptor antagonist significantly reduced hyperalgesia, allodynia, and c-fos positive cells. These findings suggested that EP1 receptor antagonists may have a role in treatment of neuropathic pain.
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Anesthesia and analgesia · Oct 2001
Case ReportsPractical issues in bispectral analysis of electroencephalographic signals.
The aim of this report was to confirm the methodology of bispectral analysis of electroencephalogram. In developing a software for real-time bispectral analysis, we encountered several practical problems in bispectrum calculation. We settled those and concluded that 3 min of monitoring are required to obtain reliable and reproducible bicoherence values.