Extent and Localization of Changes in Upper Airway Caliber with Varying Concentrations of Sevoflurane in Children

Background: Previous studies in humans suggest that inhibition of upper airway muscle activity is independent of the dose of inhalational anesthesia. Whether a dose-independent relation applies to changes in airway caliber is unknown. The authors sought to evaluate the configurational changes that lead to upper airway narrowing during inhalational anesthesia with sevoflurane and to determine whether these changes are dose dependent within a clinically relevant dose range.

Methods: Fifteen children undergoing elective magnetic resonance imaging of the brain were studied. Magnetic resonance images of the upper airway were acquired at sevoflurane concentrations of 0.5, 1.0, and 1.5 minimum alveolar concentration (MAC), administered in random sequence. At least 15 min was allowed for equilibration of inspired and alveolar partial pressures of sevoflurane. Images were acquired in early expiration at the level of the soft palate, base of the tongue, and tip of the epiglottis. Airway cross-sectional area (CSA), anteroposterior, and transverse dimension were determined using image-analysis software.

Results: At each anatomical level, pharyngeal CSA decreased progressively with increasing depth of sevoflurane anesthesia (P < 0.001). Increasing the sevoflurane concentration from 0.5 to 1.0 MAC reduced airway CSA by 13-18%, and a further increase to 1.5 MAC resulted in an overall 28-34% reduction in CSA. The reduction in CSA was predominantly due to a decrease in anteroposterior dimension.     

CT diagnosis of paraduodenal hernia.

The computed tomographic (CT) findings of a right and left paraduodenal hernia are described. In the right paraduodenal hernia the major findings consist of encapsulation of small bowel loops in the right mid-abdomen with looping of arterial and venous jejunal branches behind the superior mesenteric artery. The findings of the left paraduodenal hernia are less specific and involve encapsulation of bowel loops at or above the level of the ligament of Treitz with intermittent dilatation.     

Portaclamp in video-assisted minimally invasive cardiac surgery: Surgical technique and preliminary clinical experience

Video-assisted minimally invasive cardiac surgery (VAMICS) is currently performed with various indications. However, despite the increasing evidence of its effectiveness, new approaches have to be defined to simplify this procedure, minimize its potential complications and limit its costs, for a wider use in the surgical community. The limited access to the aorta is a key point in VAMICS and mandates specific clamping modalities with their own limitations, costs and drawbacks. The Portaclamp (Cardio Life Research SA, Louvain la Neuve, Belgium), a new autoguided extravascular aortic cross-clamping system, has been recently proposed to facilitate VAMICS. Herein, we describe the Portaclamp approach and report our indications and preliminary clinical experience so to define its role in VAMICS.     

FTIR spectra and chain conformations in the crystalline forms and clathrates of syndiotactic poly(p-methylstyrene)

Infrared spectra of syndiotactic poly(p-methylstyrene) (s-PPMS) samples, exhibiting various crystalline forms and clathrate structures, are reported in this contribution. Bands due to the syndiotactic stereostructure, bands typical of the two different chain conformations observed in the crystalline structures and bands sensitive to intermolecular interactions typical of the different modes of packing of chains are pointed out. The observed similarities with the case of syndiotactic polystyrene are alos indicated. A complete assignment, via FTIR analysis, of the chain conformations, is presented for all the known crystalline forms and clathrates of s-PPMS.     

Effects of pyridostigmine on spontaneous and growth hormone-releasing hormone stimulated growth hormone secretion in children on daily glucocorticoid therapy after liver transplantation

OBJECTIVES: We aimed to investigate both nocturnal spontaneous and morning growth hormone (GH)-releasing hormone (GHRH)-induced GH secretion in children on daily glucocorticoid treatment after liver transplantation and to evaluate the effect of pyridostigmine (an acetylcholinesterase inhibitor thought to reduce hypothalamic somatostatin tone) on GH secretion in these patients. DESIGN: We performed a randomized, single-blind, cross-over study. PATIENTS: We studied three male and three female juvenile patients, within a year of orthotopic liver transplantation and under immunosuppressive glucocorticoid therapy (mean dose +/- SEM, 5.92 +/- 0.63 mg/day) and five normal children (four males, one female). MEASUREMENTS: Both nocturnal spontaneous and morning GHRH-induced GH secretion were evaluated after administration of placebo, 1 tablet p.o., or pyridostigmine, 2 mg/kg p.o. RESULTS: Spontaneous GH. Placebo: in liver transplanted children nocturnal GH secretion (mean GH level 10.8 +/- 2.0 mU/l) was not significantly different with respect to normal children (mean GH level 12.8 +/- 1.2 mU/l); pyridostigmine: nocturnal GH secretion was significantly increased as compared to placebo in subjects with liver transplantation but not in normal children. GHRH test. Placebo: liver transplanted patients showed a blunted GH response to GHRH with respect to normal children; pyridostigmine: the GH responses to GHRH (P less than 0.05) increased as compared to placebo and did not differ significantly in the two groups. CONCLUSIONS: Our data suggest a steroid-mediated increase in hypothalamic somatostatin tone in liver transplanted children.     

Alcohol Intake and Withdrawal: Effects on Branched Chain Amino Acids and Alanine

The effects of chronic alcohol consumption on plasma branched chain amino acids and alanine concentrations were evaluated, and basal blood concentrations of these amino acids were determined after chronic ethanol intake and following a withdrawal period in 30 admitted alcoholics. After ethanol intake, alcoholics showed increased branched chain amino acid concentrations; the blood alanine concentrations were depressed after the withdrawal period. To evaluate the effect of ethanol on diurnal variations of these amino acids in the blood, a group of these patients underwent two isocaloric diets with and without wine. The diet with alcohol induced a sustained increase of branched chain amino acids persisting even after the postprandial phase with a decrease of alanine as compared to the diet without.