A Multicenter Study Comparing the ProSealTM and ClassicTM Laryngeal Mask Airway in Anesthetized, Nonparalyzed Patients

Background: The laryngeal mask airway ProSeal(TM) (PLMA(TM)), a new laryngeal mask device, was compared with the laryngeal mask airway Classic(TM) (LMA(TM)) with respect to: (1) insertion success rates and times; (2) efficacy of seal; (3) fiberoptically determined anatomic position; (4) orogastric tube insertion success rates and times; (5) total intraoperative complications; and (6) postoperative sore throat in nonparalyzed adult patients undergoing general anesthesia, hypothesizing that these would be different.

Methods: Three hundred eighty-four nonparalyzed anesthetized adult patients (American Society of Anesthesiologists physical status I-II) were randomly allocated to the PLMA(TM) or LMA(TM) for airway management. In addition, 50% of patients were randomized for orogastric tube placement. Unblinded observers collected intraoperative data, and blinded observers collected postoperative data.

Results: First-attempt insertion success rates (91 vs. 82%, P = 0.015) were higher for the LMA(TM), but after three attempts success rates were similar (LMA(TM), 100%;PLMA(TM), 98%). Less time was required to achieve an effective airway with the LMA(TM) (31 +/- 30 vs. 41 +/- 49 s;P = 0.02). The PLMA(TM) formed a more effective seal (27 +/- 7 vs. 22 +/- 6 cm H2O;P < 0.0001). Fiberoptically determined anatomic position was better with the LMA(TM) (P < 0.0001). Orogastric tube insertion was more successful after two attempts (88 vs. 55%;P < 0.0001) and quicker (22 +/- 18 vs. 38 +/- 56 s) with the PLMA(TM). During maintenance, the PLMA(TM) failed twice (leak, stridor) and the LMA(TM) failed once (laryngospasm). Total intraoperative complications were similar for both groups. The incidence of postoperative sore throat was similar.     

Pharmacokinetics and Pharmacodynamics of Vecuronium in Rats with Systemic Inflammatory Response Syndrome: Treatment with NG-Monomethyl-L-Arginine

Background: Insufficient detoxification caused by nitric oxide-related inhibition of cytochrome P450 may be important for metabolism of numerous drugs, including vecuronium. The present study investigated the pharmacodynamics and pharmacokinetics of vecuronium in rats with inflammatory liver dysfunction.

Methods: Male Sprague-Dawley rats (n = 56) were randomly allocated into two groups: In the sepsis group, liver inflammation was established by injection of 56 mg/kg heat-killed Corynebacterium parvum; control rats received the solvent. At day 4, groups were subdivided according to treatment with the nitric oxide synthase inhibitor NG-monomethyl-L-arginine (250 mg/kg) or placebo. The aminopyrine breath test was performed to assess cytochrome P450 activity. Rats were anesthetized with propofol and mechanically ventilated. Duration of action of vecuronium (1.2 mg/kg) was measured by evoked mechanomyography (stimulation of the sciatic nerve, contraction of the gastrocnemius muscle). In seven rats of each subgroup a 50% neuromuscular blockade was established by a continuous vecuronium infusion. Vecuronium plasma levels were measured and plasma clearance of vecuronium was calculated. Nitric oxide synthesis was assessed by measuring nitrite/nitrate serum levels.

Results: In sepsis/placebo rats, vecuronium-induced neuromuscular blockade was prolonged (144% of control/placebo), vecuronium plasma levels at 50% neuromuscular blockade were increased (122% of control/placebo), and plasma clearance was decreased (68% of control/placebo). NG-monomethyl-L-arginine therapy in rats with sepsis improved cytochrome P450 activity and plasma clearance of vecuronium, shortened duration of action of vecuronium, but did not alter the elevated vecuronium plasma levels.     

Giant fibroadenoma of the breast in adolescents : Report of 2 cases

Giant fibroadenoma (GF) is an uncommon variant of fibroadenomas that represent the most frequent breast lesion in adolescents and young women.The authors present 2 cases of GF of the breast in girls aged 12 and 14 years, and the respective diagnostic workup and conservative surgical treatment. Giant fibroadenomas are benign tumors, but their rapid growth and large size together with their rarity may determine difficulties in the clinical approach. Moreover, GF must be excised in all cases to exclude a phyllodes tumor and to prevent later deformity.     

Schulterarthrodese Indikation, Technik, Ergebnisse, Komplikationen

Aktuell stellen insbesondere Lähmungen, neben ausgedehnten Rotatorenmanschettendefekten, nicht beherrschbaren Schulterinstabilitäten und vorliegenden Resektionszuständen, eine geeignete Indikation zur Schulterarthrodese dar.Durch die Arthrodese der Schulter kommt es nicht, wie an anderen Gelenken, zu einem Funktionsverlust, sondern es entsteht teilweise sogar ein Zuwachs an aktiver Schulterbeweglichkeit. Die Angaben zum aktiven postoperativen Bewegungsausmaß schwanken für Abduktion und Anteversion zwischen 30° und 90°, durchschnittlich werden etwa 60° erreicht.     

Potency of Bupivacaine Stereoisomers Tested In Vitro and In Vivo: Biochemical, Electrophysiological, and Neurobehavioral Studies

Background: Chiral local anesthetics, such as ropivacaine and levobupivacaine, have the potential advantage over racemic mixtures in showing reduced toxic side effects. However, these S-(levo, or "-")isomers also have reportedly lower potency than their optical antipode, possibly resulting in no advantage in therapeutic index. Potency for local anesthetics inhibiting Na+ channels or action potentials depends on the pattern of membrane potential and so also does the stereopotency ratio. Here the authors have quantitated the stereopotencies of R-, S-, and racemic bupivacaine, comparing several in vitro assays of neuronal Na+ channels with those from in vivo functional nerve block, to establish relative potencies and to understand better the role of different modes of channel inhibition in overall functional anesthesia.

Methods: The binding of bupivacaine to Na+ channels was assessed indirectly by its antagonism of [3H]-batrachotoxin binding to rat brain synaptosomes. Inhibition of Na+ currents by bupivacaine was directly assayed in voltage-clamped GH-3 neuroendocrine cells. Neurobehavioral functions were disrupted by bupivacaine percutaneously injected (0.1 ml; 0.0625-1.0%) at the rat sciatic nerve and semiquantitatively assayed. Concentration-dependent actions of R-, S-, and racemic bupivacaine were compared for their magnitude and duration of action.

Results: Competitive batrachotoxin displacement has a stereopotency ratio of R :S = 3:1. Inhibition of Na+ currents with different prepulse potentials shows that S > R potency when the membrane is hyperpolarized, and R >S potency when it is depolarized from normal resting values. Functional deficits assayed in vivo usually demonstrate no consistent enantioselectivity and only a modest stereopotency (R :S = 1.2-1.3) for peak analgesia achieved at the lowest doses. Other functions display no significant stereopotency in either the degree, the duration, or their product (area under the curve) at any dose.     

Heart Transplantation: A Single-Center Experience

Background. The success of heart transplantation led to the extension of the criteria for both recipients and donors. The aim of the study was to evaluate the experience with this therapeutic approach for end-stage heart failure at a single center.

Methods. Between April 1986 and January 1996, 1,413 patients were accepted as candidates for heart transplantation. Ventricular assist devices were used as a bridge to transplantation in 173 patients (biventricular assist device in 141 patients and left ventricular assist device in 32 patients). The longest duration of support was 572 days (average, 46 days).

Results. Of the 1,413 patients, 891 underwent heart transplantation (65 children/adolescents and 826 adults; 522 (36%) patients died awaiting a donor heart. The average time spent on the waiting list was 107 days. The average recipient age was 44 years, and the age of donors was extended up to 69 years. Eighty-three patients with ventricular assist devices (48%) subsequently underwent heart transplantation. Twenty-five patients (2.7%) underwent retransplantation. The 30-day mortality rate was 14%, and the overall actual survival at 1, 5, and 10 years was 80%, 59%, and 50%, respectively. Ninty-four percent of patients were in New York Heart Association functional class I or II at 1 year, and 44% returned to work after transplantation.

Conclusions. Despite the broadening of the selection criteria for both recipients and donors, heart transplantation remains an effective treatment for end-stage heart failure. Nevertheless, this therapeutic approach is severely limited by a considerable disparity between the need and availability of donor organs.