Anesthesia and analgesia
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Anesthesia and analgesia · Mar 1997
An analysis of the predictive probability of the in vitro contracture test for determining susceptibility to malignant hyperthermia.
An objective estimate of the likelihood of correct designation of malignant hyperthermia (MH) susceptibility from in vitro contracture test (IVCT) results is essential if genetic linkage studies of MH are to be more informative. The aim of this study was to generate and test statistical models that could be used to predict the probability of susceptibility of an individual to MH from the results of their IVCTs. Logistic regression of the IVCT results of an index group of 50 patients (age range 9-73 years; MH susceptible [MHS], n = 13; MH normal [MHN], n = 32; MH equivocal [MHE], n = 5) who were either at low risk of MH or were proband cases were used to generate models to predict probability of MH susceptibility. ⋯ A further group of 153 patients (age range 9-74 years; MHS, n = 44; MHN, n = 92; MHE, n = 17) who were consecutively tested relatives of susceptible individuals was used to assess the generalizability of the best model. The model met the criteria for a useful discriminatory model with this group of patients, 125 of whom (including 9 MHE patients) could be designated as positive or negative for MH with a likelihood of more than 95%. The logistic regression models provide objective likelihoods for the MH phenotype that could be usefully incorporated into genetic linkage studies of the condition.
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Anesthesia and analgesia · Mar 1997
Clinical TrialEfficacy of the self-inflating bulb in differentiating esophageal from tracheal intubation in the parturient undergoing cesarean section.
We studied the efficacy of the self-inflating bulb (SIB) in differentiating tracheal from esophageal intubation in 40 parturients undergoing elective cesarean section under general anesthesia. After induction and muscle relaxation, the trachea was intubated under direct vision with cuffed tube. In 20 parturients, the esophagus was also intubated with an identical tube. ⋯ The incidence of false positive results immediately after induction was 30% with T1 and 35% with T2. The mechanism of false negative responses may be attributed to decreased functional residual capacity leading to reduced caliber of intrathoracic airways and terminal airway closure; whereas false positive responses may be related to an incompetent gastroesophageal junction. We conclude that the SIB is unreliable for differentiating tracheal from esophageal intubation in the parturient undergoing cesarean section.
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Anesthesia and analgesia · Mar 1997
Magnetic resonance imaging of cerebrospinal fluid leak and tamponade effect of blood patch in postdural puncture headache.
This prospective study examined the efficacy of magnetic resonance imaging (MRI) in visualizing cerebrospinal fluid (CSF) leak in patients with postdural puncture headache (PDPH) and determining the spread of the blood patch in the epidural space and the extent of tamponade on the thecal sac. After obtaining institutional review board approval, five patients with symptomatic PDPH after 3 days of failed conservative treatment were included in this study. MRI using proton density (PD) and T2-weighted imaging was performed on all patients and CSF flow studies were done on one patient. ⋯ The tamponade effect of the blood patch was observed on PD, T2-weighted, and CSF flow images. All patients experienced immediate resolution of their symptoms. This study suggests that using MRI, the site of the CSF leak, the tamponade effect of the blood patch, and its spread in the epidural space can be documented.
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Anesthesia and analgesia · Mar 1997
Peripherally administrated morphine attenuates capsaicin-induced mechanical hypersensitivity in humans.
We examined the hypothesis that peripheral morphine can modulate pain and hyperalgesia/allodynia in the human capsaicin model. Subcutaneous injections of 1 mL morphine (1 mg/mL) in one arm and of 1 mL 0.9% saline in the other arm were made prior to bilateral intradermal injections of 50 microL (6 mg/mL) capsaicin. All injections were made on the volar aspect of the arm. ⋯ Capsaicin injection resulted in spontaneous pain on the saline-injected side not significantly different from that on the morphine-injected side. However, capsaicin injections gave rise to significantly less pain evoked by mechanical stimuli, as well as to a significantly smaller area of mechanical hypersensitivity, on the morphine-injected side compared with the saline-injected side. These results suggest that morphine can modulate sensitization mechanisms involved in the development of capsaicin-induced mechanical hypersensitivity.
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Anesthesia and analgesia · Mar 1997
Clinical TrialPlasma concentrations of bupivacaine in neonates after continuous epidural infusion.
This study reports plasma bupivacaine concentrations in 13 neonates who received lumbar epidural anesthesia during major abdominal surgery. A bolus of 1.8 mg/kg of bupivacaine (2.5 mg/mL) was administered after induction of anesthesia, followed by a continuous infusion of 0.2 mg.kg-1.h-1 (1.25 mg/mL). Plasma concentrations of total and free bupivacaine and alpha 1-acid-glycoprotein (AAG) were determined. ⋯ However, a substantial number of patients still had increasing concentrations of total plasma bupivacaine at 48 h. Furthermore, the interindividual variation was considerable. These observations cause concern about the safety of epidural infusions longer than 48 h in the age group studied.