Anesthesia and analgesia
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Anesthesia and analgesia · Dec 1999
Randomized Controlled Trial Clinical TrialThe ulinastatin-induced effect on neuromuscular block caused by vecuronium.
We examined the effect of ulinastatin, a protease inhibitor purified from human urine, on neuromuscular block caused by vecuronium. Sixty adult patients were randomly divided into four groups of 15 patients each: ulinastatin-posttetanic count (U-PTC), ulinastatin-train-of-four (U-TOF), control-posttetanic count (C-PTC) or control-train-of-four (C-TOF) group. In the U-PTC and U-TOF groups, a bolus dose of ulinastatin 5000 U/kg was administered 2 min before the injection of vecuronium 0.1 mg/kg. In the C-PTC and C-TOF groups, normal saline was administered instead of ulinastatin. The onset of neuromuscular block in the U-PTC and U-TOF groups was significantly slower than in the C-PTC and C-TOF groups (250+/-49 vs 214+/-35 s, mean +/- SD, P < 0.05). The time from the vecuronium injection to the return of PTC in the U-PTC group was significantly shorter than in the C-PTC group (11.0+/-2.8 vs 17.6+/-6.8 min, P < 0.05). Similarly, times to the returns of T1, T2, T3, and T4 (first, second, third, and fourth stimulation of TOF) in the U-TOF group were significantly shorter than in the C-TOF group (18.5+/-5.0 vs 28.0+/-9.1 min for T1, P < 0.05). PTC in the U-PTC group was significantly higher than in the C-PTC Group 10-30 min after the administration of vecuronium (P < 0.05). T1/control twitch height and TOF ratios in the U-TOF group were significantly higher than those in the C-TOF Group 30-70 min and 40-70 min after the administration of vecuronium, respectively (P < 0.05). Ulinastatin delays the onset of neuromuscular block and hastens its recovery caused by vecuronium. ⋯ Ulinastatin delays the onset of neuromuscular block and hastens its recovery caused by vecuronium. This is because ulinastatin may release acetylcholine at the neuromuscular junction and increase hepatic and/or renal clearance of vecuronium.
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Anesthesia and analgesia · Dec 1999
Comparative Study Clinical TrialThe hemodynamic effects of anesthetic induction in vascular surgical patients chronically treated with angiotensin II receptor antagonists.
The use of angiotensin II receptor subtype-1 antagonists (ARA), recently introduced as antihypertensive drugs, is becoming more prevalent. We studied the prevalence and severity of hypotension after the induction of general anesthesia in 12 patients treated with ARA until the morning of surgery. The hemodynamic response to induction was compared with that of patients treated with beta-adrenergic blockers (BB) and/or calcium channel blockers (CB) (BB/CB group, n = 45) and angiotensin-converting enzyme inhibitors (ACEI) (ACEI group, n = 27). A standardized anesthesia induction protocol was followed for all patients. Hypotension occurred significantly (p < or = 0.05) more often in ARA-treated patients (12 of 12) compared with BB/CB-treated patients (27 of 45) or with ACEI-treated patients (18 of 27). There was a significantly (P < or = 0.001) increased ephedrine requirement in the ARA group (21+/-3 mg) compared with the BB/CB group (10+/-6 mg) or the ACEI group (7+/-4 mg). Hypotension refractory to repeated ephedrine or phenylephrine administration occurred significantly (P < or = 0.05) more in the ARA group (4 of 12) compared with the BB/CB group (0 of 45) or the ACEI group (1 of 27), but it was treated successfully by using a vasopressin system agonist. Treatment with angiotensin II antagonism until the day of surgery is associated with severe hypotension after the induction of anesthesia, which, in some cases, can only be treated with an agonist of the vasopressin system. ⋯ Hypotensive episodes occur more frequently after anesthetic induction in patients receiving Angiotensin II receptor subtype-1 antagonists under anesthesia than with other hypotensive drugs. They are less responsive to the vasopressors ephedrine and phenylephrine. The use of a vasopressin system agonist was effective in restoring blood pressure when hypotension was refractory to conventional therapy.
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Anesthesia and analgesia · Dec 1999
Comparative StudyAnatomical landmarks for femoral nerve block: a comparison of four needle insertion sites.
The site for needle insertion in femoral nerve block varies significantly among various descriptions of the technique. To determine the site with the highest likelihood of needle-femoral nerve contact, femoral nerve block was simulated in a human cadaver model (17 femoral triangles from 9 adult cadavers). Four 20-gauge 50-mm-long styletted catheters were inserted at four frequently suggested insertion sites for femoral nerve block. At the levels of inguinal ligament and the inguinal crease, the catheters were inserted adjacent to the lateral border of the femoral artery and 2 cm lateral to the femoral artery. During anatomical dissection, we studied the number of catheter-nerve contacts for each of the four insertion sites, and relationships between the femoral nerve and other anatomical structures of relevance to femoral nerve block. Insertion of the needle at the level of the inguinal crease, next to the lateral border of the femoral artery resulted in the highest frequency of needle-femoral nerve contacts (71%). Of note, the femoral nerve was significantly wider (14.0 vs 9.8 mm) and closer to the fascia lata (6.8 vs 26.4 mm) at the inguinal crease than at the inguinal ligament level. We conclude that needle insertion at the inguinal crease level immediately adjacent to the femoral artery produced the highest rate of needle-femoral nerve contacts. The main factors influencing this result include the greater width of the femoral nerve and the more predictable femoral artery-femoral nerve relationship at the inguinal crease level, compared with the inguinal ligament level. ⋯ Insertion of a needle at the inguinal crease level and immediately adjacent to the lateral border of the femoral artery results in a high rate of needle-femoral nerve contact.
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Anesthesia and analgesia · Dec 1999
Comparative Study Clinical TrialThe pain visual analog scale: is it linear or nonlinear?
The visual analog scale (VAS) is a tool widely used to measure pain, yet controversy surrounds whether the VAS score is ratio or ordinal data. We studied 52 postoperative patients and measured their pain intensity using the VAS. We then asked them to consider different amounts of pain (conceptually twice as much and then half as much) and asked them to repeat their VAS rating after each consideration (VAS2 and VAS3, respectively). Patients with unrelieved pain had their pain treated with IV fentanyl and were then asked to rate their pain intensity when they considered they had half as much pain. We compared the baseline VAS (VAS1) with VAS2 and VAS3. The mean (95% confidence interval) for VAS2:1 was 2.12 (1.81-2.43) and VAS3:1 was 0.45 (0.38-0.52). We conclude that the VAS is linear for mild-to-moderate pain, and the VAS score can be treated as ratio data. ⋯ A change in the visual analog scale score represents a relative change in the magnitude of pain sensation. Use of the VAS in comparative analgesic trials can now meaningfully quantify differences in potency and efficacy.
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Anesthesia and analgesia · Dec 1999
Assessing platelet and fibrinogen contribution to clot strength using modified thromboelastography in pregnant women.
The monoclonal antibody fragment c7E3 Fab (ReoPro), by binding to platelet surface fibrinogen receptors (glycoprotein, GPIIb/IIIa), inhibits platelet aggregation and its interaction with fibrinogen. In this study, we used thromboelastography with ReoPro to evaluate the independent contribution of fibrinogen and platelets to clot strength. Thromboelastography was performed in 21 healthy, term parturients scheduled for elective cesarean delivery with 360 microL of celite-activated whole blood and with 5 microL of (2 mg/mL) ReoPro added to 355 microL of celite-activated whole blood. The contribution of platelets to clot strength (MAplt) was derived by subtracting MAfib (maximal amplitude with ReoPro) from MAwb (maximal amplitude with whole blood). Thus, MAwb - MAfib = MAplt. The value for MAwb (mean +/- SD) was 73+/-4 mm, for MAfib it was 33+/-5 mm, and for MAplt it was 40+/-3 mm. The contribution of fibrinogen and platelets to the MAplt was 45% and 55%, respectively. Modified thromboelastography using ReoPro in healthy parturients can be used to determine the contribution of fibrinogen and platelets to blood clot strength. ⋯ Determining the independent contribution of platelets and fibrinogen to the maximal amplitude of thromboelastography using c7E3 Fab may further improve the use of thromboelastography in detecting and treating coagulation defects.