Cardiac arrest and myocardial infarction induced by postpartum intravenous ergonovine administration.
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Adult↗
Biomedical subjects
B C Tsui
Publications and source records attributed to B C Tsui.
Detection of subdural placement of epidural catheter using nerve stimulation.
PURPOSE: To report the detection of a subdural catheter placement using nerve stimulation through an epidural catheter. CLINICAL FEATURES: An 85-yr-old gentleman was scheduled for radical cystectomy and creation of an ileal conduit. Combined general anesthesia and regional technqiue was selected. An epidural catheter (19 G Arrow Flextip Plus) was inserted prior to induction of general anesthesia. Intra-operatively, the patient received 5 mg morphine and 10 ml bupivacane 0.5% via the epidural catheter. The patient remained hemodynamically stable throughout the operation and did not require intravenous opioids. The patient was discharged to the ward with an order for epidural morphine for pain control. The next day, the patient remained comfortable. As an ongoing quality assessment to survey the success rate of epidural catheters at our institution, all patients are invited to have their catheter assessed using an electrical epidural stimulation test. Electrical stimulation (1-10 mA) with a segmental motor response (truncal or extremities movement) indicates that the catheter is in the epidural space. No motor response indicates that it is not. In this case, subdural catheter placement was suspected because a diffuse motor response including right anterior chest wall, back muscle, and bilateral lower extremities was observed using only 0.3 mA. Subdural catheter placement was subsequently confirmed by a radiograph showing a very thin film of dye spreading cephalad and caudad over many segments. CONCLUSION: This new electrical test helps to detect subdural placement objectively.
Aged↗
Estimation of desflurane concentration using isoflurane channel in optical infrared analyzer.
PURPOSE: To estimate desflurane concentration on the isoflurane channel in an optical infrared analyzer using a simple regression equation. METHODS: Desflurane in concentrations of 0% to 3% in 0.5% increments and 3% to 12% in 1% increments in 2 L.min-1 oxygen was delivered simultaneously to an Ohmeda 5250 RGM desflurane channel, an Ohmeda 5250 RGM isoflurane channel, and a Datex Capnomac Ultima isoflurane channel at room temperature and atmospheric pressure. For each concentration increment, the displayed gas concentrations were recorded. By comparing the readings from the desflurane channel of Ohmeda RGM and the isoflurane channels from Ohmeda RGM and Datex Capnomac Ultima respectively, the linear regression relationship and the slope of the fitted line (conversion factor) between two channels were obtained. Similar measurements were performed using 2 L.min-1 mixture of nitrous oxide 50% and oxygen 50%. The measurements were repeated with different monitors three months later. RESULTS: All four analysers tested were linear (r2 > 0.9) for measuring desflurane using isoflurane channels over the range of concentrations studied on two different days. The accuracy of the estimation using the mean conversion factor of the four monitors was within 10% error from the readings of the commercially available desflurane channel analyzer. There was no noticeable effect on the slope (conversion factor) of the linear regression with O2 100% or 50/50 mixture of N2O and O2. CONCLUSION: The concentration of desflurane can be estimated by a simple conversion factor using an isoflurane channel of an infrared system.
Analysis of Variance↗
Loss of resistance to saline -- does the dripping bother you?
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Anesthesia, Epidural↗
Detection of subarachnoid and intravascular epidural catheter placement.
PURPOSE: To report the detection of subarachnoid and intravascular catheter placement using nerve stimulation through an epidural catheter. CLINICAL FEATURES: Electrical stimulation (1-10 mA) was applied through the catheter. A positive motor response (truncal or limb movement) indicated that the catheter was in the epidural space. Absence of a motor response indicated that it was not. A low milliamperage (<1 mA) with bilateral response indicated subarachnoid placement. Intravascular catheter placement was indicated by a positive response to the test, which remains at or returns to the baseline levels (i.e. prior to any local anesthetic injection), despite the administration of local anesthetics. In the first patient, the test confirmed subarachnoid catheter placement during attempts at continuous spinal anaesthesia even though CSF could not be aspirated. Bilateral motor response in the legs was observed at 0.2 mA. In the second patient, inadvertent subarachnoid placement was detected during attempted lumbar epidural block by observing bilateral motor response in the legs at 0.3 mA. In the third patient, intravascular placement was suspected and confirmed by failure to obliterate the motor response despite repeated local anesthetic injection. CONCLUSION: The new test provides objective information in managing epidural catheters when their position is uncertain.
Adult↗
Thoracic epidural analgesia via the caudal approach using nerve stimulation in an infant with CATCH22.
PURPOSE: To illustrate insertion of an epidural catheter via caudal route in a small infant under electrical stimulation guidance. CLINICAL FEATURES: A six month old boy, weighting 4.25 kg, with a diagnosis of CATCH22 (Cardiac abnormality/abnormal faces, T cell deficit due to thymic hypoplasia, cleft palate, hypocalcemia due to hypoparathyroidism resulting from 22q11 deletion) was scheduled for fundoplication and gastrostomy tube (G-tube) insertion. A combined light general anesthesia and continuous epidural anesthesia technique was selected. Following induction of general anesthesia and tracheal intubation with 1.5 mg midazolam, 10 microg fentanyl and 10 mg succinylcholine, a 16G intravenous catheter was inserted into the caudal space. A 19G epidural catheter (Arrow Flextip Plus) epidural catheter was then inserted up cranially. A low electrical current (1-10mA) was then applied through the catheter. The level of motor movement was advanced from the lower limb muscles to the upper abdominal muscles as the catheter was threaded cranially. After 19 cm of epidural catheter had been inserted, intercostal muscle movement (T9-10 level) was observed at 4.2mA. The tip of the catheter was later confirmed to be at the T9-10 interspace by radiographical imaging. The patient awakened without distress and the trachea was extubated the same evening. The infant was discharged to the ward next morning with good pain relief from a continuous epidural infusion of bupivacane 0.1% with 1 microg x ml(-1) at 1.6 ml(-1). CONCLUSION: Epidural stimulation may help placement of the epidural catheter at the appropriate dermatome for effective anesthesia and analgesia.
Abnormalities, Multiple↗
Confirmation of caudal needle placement using nerve stimulation.
BACKGROUND: The study was designed to examine a new method of confirming proper caudal needle placement using nerve stimulation. METHODS: Thirty-two pediatric patients were studied. A 22-gauge insulated needle was inserted into the caudal canal via the sacral notch until a "pop" was felt. The needle placement was classified as correct or incorrect depending upon the presence or absence of anal sphincter contraction (S2-S4) to electrical simulation (1 to 10 mA). RESULTS: Three patients were excluded, two because they inadvertently received neuromuscular blockers and one because the patient's anatomy precluded any attempt at a caudal block. The sensitivity and specificity of the test were both 100% in predicting clinical outcomes of the caudal block. Six patients had a negative stimulation test after the first attempt to place the needle. Four of these went on to receive a second attempt of needle insertion after a subcutaneous bulge or resistance to local anesthetic injection were observed. Following needle reinsertion, positive stimulation tests were elicited. These patients received the local anesthetic injection with ease and had good analgesia postoperatively. No attempt was made to reinsert the needle in the remaining two patients with a negative stimulation test, as they did not show subcutaneous bulge or resistance upon injection. These patients had poor analgesia postoperatively. The positive predictive value of the test was greater than the presence of a "pop" alone (P < 0.05) but not significantly different (P = 0.492) over the presence of "pop" and easy injection. CONCLUSION: This test may be used as a teaching and adjuvant tool in performing caudal block.
Anesthesia, Caudal↗
Confirmation of epidural catheter placement using nerve stimulation.
PURPOSE: To examine the reliability of low current electrical epidural stimulation to confirm epidural catheter placement. METHODS: Forty patients with epidural catheters (19G Arrow Flextip plus) already in place for post-operative pain management were studied. An adapter (Arrow-Johans ECG Adapter) was attached to the connector of the epidural catheter. The epidural catheter and adapter were filled with normal saline. The cathode lead of the nerve stimulator was attached to the metal hub of the adapter. Catheter placement was judged to be correct or incorrect, depending upon the presence or absence of truncal or limb movement to 1 Hz stimulation (1-10 mA). A standard test dose (3 ml lidocaine 1.5% with 1:200,000 epinephrine) was then injected. The efficacy of the epidural morphine was assessed independently. RESULTS: The sensitivity and specificity of the test was 100% and 91.6% compared with the standard test dose. The positive and negative predictive value was 96% and 100%. In predicting the clinical effect of epidural morphine, the sensitivity and specificity was 96.1% and 76.9%. The positive and negative predictive value was 89% and 90%. The correlation of unilateral or bilateral motor response from the test and sensory response from the lidocaine test with sensitivity and specificity was 91.6% and 53.0%. The predictive value for unilateral response was 61% and for bilateral was 88%. CONCLUSION: This study establishes this test as a simple, objective and reliable technique for confirmation of epidural catheter placement.
Analgesia, Epidural↗
A rapid precurarization technique using rocuronium.
PURPOSE: To evaluate a rapid and time-saving precurarization technique using rocuronium to prevent succinylcholine-induced myalgia. METHOD: In a prospective, double blind randomized study, 42 ASA 1-2 patients were assigned to one of three pretreatment groups: 0.01 ml.kg-1 normal saline, 0.1 mg.kg-1 atracurium, and 0.1 mg.kg-1 rocuronium. Anaesthesia commenced with 1.5 micrograms.kg-1 fentanyl and 0.5 mg.kg-1 lidocaine at time zero. Pretreatment was administered 60 sec later, followed by 2.5 mg.kg-1 propofol. At 90 sec, 1.5 mg.kg-1 succinylcholine was injected and 30 sec later, the trachea was intubated and the ease of intubation was graded. The patient was observed for the presence and severity of fasciculations. Myalgias were recorded on postoperative days 1, 2 and 7. RESULTS: The incidence of fasciculations in the rocuronium group (21.4%) was lower (P < 0.001) than atracurium (78.5%) or placebo (92.8%) groups. On postoperative day 1, the incidence of postoperative myalgia in the rocuronium group (14.2%) was less than the placebo group (78.2%; P < 0.002) and atracurium group (85.7%; P < 0.001). The incidence of myalgia in the rocuronium group (7.1%) was lower than in the placebo group (78.5%; P < 0.001) but not different from the atracurium group (42.8%; P = 0.077) on postoperative day 2. On postoperative day 7, there was no difference among the three groups. Fasciculations were related to postoperative myalgia. There was no difference in intubating conditions among the three groups. CONCLUSION: Rocuronium pretreatment given just before induction of anaesthesia with propofol reduces fasciculations and succinylcholine-induced myalgia.
Adult↗
Pharmacokinetics and haemodynamic effect of diltiazem in rats: effect of route of administration.
Diltiazem is a calcium antagonist widely used for the treatment of angina and hypertension. Previous studies in patients have shown that the haemodynamic effects of diltiazem are greater after parenteral rather than oral administration. The rat has been used as an animal model to determine the effect of the route of administration on the pharmacokinetic and haemodynamic effects of diltiazem. The results showed that plasma concentrations of diltiazem were more than 10 times higher after the intra-arterial dose. The plasma concentrations of the major metabolites were also higher after intra-arterial administration, although only for deacetyl diltiazem (M1) did the difference reach statistical significance (P < 0.05). The haemodynamic effects (on blood pressure and heart rate) of diltiazem were considerably greater after intra-arterial administration; this was attributed mainly to the much higher plasma concentrations of diltiazem. The hypotensive and chronotropic effects of diltiazem were similar; Emax and EC50 for diastolic blood pressure were 72+/-19% and 4.4+/-5.9 microg mL(-1); for heart rate they were 77+/-32% and 10.0+/-11.7 microg mL(-1), respectively. The haemodynamic effects of diltiazem are much greater after intra-arterial administration, mainly because of the much higher plasma concentrations of the drug. The contribution by the metabolites would be minimal after this route of administration.
Administration, Oral↗
A simple method with no additional cost for monitoring ETCO2 using a standard nasal cannulae.
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Carbon Dioxide↗
Optimal imaging techniques for locating leaflets after escape from prosthetic heart valves.
The authors report two cases of leaflets escaping from an Edwards-Duromedics bileaflet prosthetic heart valve (Baxter-Edwards Division, Baxter Healthcare Corp., Irvine, Calif.). Several imaging techniques were used in attempts to locate the leaflets. Only computed tomography (CT) led to conclusive results. Because progressive extrusion through the arterial wall was documented surgically in these cases, the authors recommend that CT be performed as early as possible after a leaflet escapes, even in asymptomatic patients. Extrusion through the arterial wall precludes percutaneous intravascular movement or retrieval of escaped leaflets.
Adult↗
A reliable technique for chronic carotid arterial catheterization in the rat.
A reliable and simple method for cannulating the carotid artery of rats is described. The rat was anesthetized with halothane. The right carotid artery located between the omohyoideus and sternohyoideus muscles was exposed through a 2-cm ventral neck incision. The catheter was made of Silastic tubing and a monofilament line, which served as an obturator and internal support. The line was then filled with a viscous mixture of heparin, polyvinylpyrrolidinone and normal saline to prevent the formation of blood clots. The catheter was advanced through the carotid artery towards the heart by a predetermined distance (15-20 mm) depending on the size of the rat. The catheter was well tolerated by the rats and the success rate was 95%. Its patency lasted for at least 7 days postsurgery without any special maintenance care. With the described method one would be able to perform repetitive blood sampling and arterial blood pressure measurements in unanesthetized and unrestrained rats for prolonged period after catheterization.
Animals↗
Pharmacokinetics and metabolism of diltiazem in rats following a single intra-arterial or single oral dose.
Diltiazem (DTZ) 20 mg/kg was given to male Sprague-Dawley rats either orally (p.o.) or intra-arterially (i.a.) over a 5 min period (n = 6 for each group). Plasma concentrations of DTZ and its major basic metabolites were determined by high performance liquid chromatography assay (HPLC) as previously described over a 10 h period. The major metabolites found in the rat plasma were M2, followed by M6, MA, M1, and then M4. The metabolite Mx was measurable only in some of the plasma samples, and MB was not detected in this species. The mean apparent half-life (t1/2) of the measurable metabolites were longer than the parent DTZ. The metabolism profiles were qualitatively similar between the two routes of administration. Quantitatively, however, the plasma concentrations of the metabolites were higher after the i.a. route. These results are in agreement with a previous study reported in rabbits, and suggest that deacetylation of DTZ and MA in the blood is extremely important in this species.
Administration, Oral↗
Anorectal fistula: an unusual presentation in a Crohn's disease patient.
An unusual case of an anorectal fistula presenting with hip pain and extensive lower limb muscle wasting in a patient with Crohn's disease is reported. This report emphasizes the important role of a thorough history, a complete physical examination, and a thorough search for evaluating such cases. Any progressive local irritation and pain in a Crohn's disease patient may indicate possible fistulous involvement. Nonspecific laboratory findings such as leukocytosis, anemia, decreased albumin level, and thrombocytosis may be considered as supportive indicators. Barium contrast studies and enhanced computed tomography scan may be helpful but can be falsely negative in the presence of a fistula, as in this case. These findings illustrate that the clinician must not be dissuaded from the diagnosis simply based on negative radiological findings because the presence of a fistula may be impossible to determine preoperatively.
Adult↗
Determining epidural catheter location using nerve stimulation with radiological confirmation.
BACKGROUND AND OBJECTIVES: The use of epidural stimulation to confirm epidural catheter placement has been shown. This case report describes the benefits and problems of using the epidural stimulation test to confirm epidural catheter placement and provides supporting evidence for these observations using radiological imaging. CASE REPORT METHODS: A nerve stimulator was connected to the proximal end of an epidural catheter via an adapter. The cathode lead was connected to the adapter. The anode lead was connected to an electrode placed on the upper extremity as a grounding site. Using 1 to 10 mA current, a segmental motor response indicated that the catheter was in the epidural space. The absence of a motor response indicated that it was not. CASES: In the first patient, the new test predicted subcutaneous epidural catheter placement, which was subsequently confirmed radiologically. In the second patient, the catheter tip was found to be lying near a nerve root, which was again confirmed radiologically. In the third case, a negative test was initially observed with only local muscle movement over the biceps area (T2). After relocation of the grounding electrode to the lower extremity, segmental intercostal muscle movement (T4-5 level) was observed. The catheter placement was radiologically shown to be in the T4-5 region. CONCLUSION: This report illustrates some of the potential benefits and problems of using the nerve stimulation test to confirm epidural catheter placement, with radiological verification.
Adult↗
Determination of epidural catheter placement using nerve stimulation in obstetric patients.
BACKGROUND AND OBJECTIVES: Peripheral nerve and spinal cord stimulation techniques have been used for many years. However, electrical stimulation methods rarely have been used to confirm epidural catheter placement. This study examines the practicality of this technique to confirm epidural catheter placement in obstetric patients. METHODS: Thirty-nine obstetric patients in labor were studied. An electrocardiography (ECG) adapter (Arrow-Johans) was attached to the proximal end of the epidural catheter (19-gauge Arrow Flextip plus). Then, the lowest milliamperage (1-10 mA) necessary to produce a motor response (truncal or limb movement) was applied using this setup. A positive motor response indicated that the catheter was in the epidural space. This test was performed initially after catheter insertion and repeatedly after incremental local anesthetic doses. RESULTS: The sensitivity and specificity of the new test was 100% and 100%, respectively, with 38 true positive tests and 1 true negative test. The threshold current required to produce a positive test increased after incremental doses of local anesthetic. A case of intravascular epidural catheter migration was detected using this new test. In this case, the patient's increased threshold milliamperage returned to the baseline value within 1 hour, despite having received local anesthetic. Intravascular epidural catheter migration was subsequently confirmed by a positive epinephrine test dose. Thus, this test appears to be a potentially useful method to detect intravascular catheter placement. CONCLUSION: This study demonstrates that this test may have a role in improving the success rate of epidural anesthesia.
Anesthesia, Epidural↗
Occult liver abscess following clinically unsuspected ingestion of foreign bodies.
Two uncommon cases of foreign body (a wooden clothespin and a toothpick) perforation of the gur with associated pyogenic liver abscesses are presented. These cases illustrate the difficulties of preoperative diagnosis. The lack of history of ingestion of foreign bodies, variable clinical presentation of the conditions and radiolucent natures of the foreign bodies all play a role in impeding the diagnosis preoperatively. This report emphasizes the role of ultrasound and computed tomographic scan in evaluating similar cases. Any patient with known risk factors for ingestion of foreign body should arouse suspicion and be investigated further.
Adult↗