A clinical comparison of the Laryngeal Tube™ and the Laryngeal Mask™ in spontaneously breathing anesthetized patients

Abstract: Background: The laryngeal mask airway (LMA) can be used in general anaesthesia without neuromuscular block. The laryngeal tube (LT) is a new airway device with similar airway features as LMA. LT is provided with a distal cuff to prevent regurgitation. In this study we compared the LMA and LT concerning patient and user aspects. Methods: Sixty patients with ASA (American Society of Anestesiologists) score 1–2 scheduled for minor surgery were randomized to be ventilated either through LMA or LT. After insertion, the number of insertion attempts, and “positioning” and “airway-assessment” was evaluated. The patients reported on “sore throat” after 30 and 60 minutes and the day after anaesthesia. Results: Gender and mean age were equal in both groups. The first insertion attempt was successful in 25 of 28 patients randomised to LMA and in 23 of 27 patients randomised to LT. LMA was evaluated to be easier in “positioning” whereas no difference in “sore throat” was reported. Conclusion: We found no difference between the LMA and the LT in terms user and patient friendliness and safety.     

Cytoskeleton-dependent activation of the inducible nitric oxide synthase in cultured aortic smooth muscle cells.

1. Vascular endothelial and smooth muscle cells generate nitric oxide (NO) via different nitric oxide synthase (NOS) isozymes. Activation of the endothelial constitutive NOS (ecNOS) contributes to the maintenance of cardiovascular homeostasis, whereas expression of the endotoxin- and cytokine-inducible pathway (iNOS) within the vascular smooth muscle is thought to be responsible for the cardiovascular collapse which occurs during septic shock and antitumour therapy with cytokines. Since the cytoskeleton is involved in the activation of certain genes and in some effects of endotoxin in macrophages, we investigated the role of microtubules and microfilaments in the activation of the NO pathway in cultured vascular cells. 2. Depolymerization of microtubules by either nocodazole or colchicine prevented lipopolysaccharide (LPS)- and interleukin-1 beta-induction of NO-dependent cyclic GMP accumulation. Steady state levels of iNOS mRNA, assessed by Northern blot and RT-PCR, and iNOS protein, assessed by Western blotting, were also decreased by either colchicine or nocodazole treatment. 3. Taxol enhanced microtubule polymerization alone, and prevented microtubule depolymerization elicited by nocodazole and colchicine. Associated with its effect on microtubule assembly, taxol prevented the inhibitory effects of nocodazole and colchicine on cyclic GMP accumulation and iNOS mRNA levels. 4. Disruption of microfilaments by cytochalasins had no inhibitory effect on the activation of the inducible NO pathway. 5. In contrast to cytokine-stimulated smooth muscle cells, modulation of either microtubule or microfilament assembly did not affect the constitutive NO pathway in endothelial cells, as endothelial cell- and NO-dependent cyclic GMP accumulation in endothelial-smooth muscle co-cultures remained unchanged. 6. Our findings demonstrate that microtubules play a prominent role in the activation of the inducible NO pathway in response to inflammatory mediators in smooth muscle cells but not of the constitutive synthesis of NO in endothelial cells.     

Localized proton spectroscopy of inoperable brain gliomas. Response to radiation therapy

Within vivo 1H-MRS resonances of several metabolites were simultaneously measured in cerebral gliomas and adjacent normal brain. 15 patients with inoperable brain gliomas all histologically verified were monitored with 1H-MRS and MRI before and after radiotherapy. 11 patients were evaluable. 1H-MRS technique evolved from single volume measurements to one dimensional and two dimensional 1H spectroscopic imaging. In all patients N-acetyl-aspartate signals were decreased in tumour areas compared to the normal brain hemisphere. No recovery was seen after radiotherapy. Choline signals were increased in tumour margins of high grade gliomas and more diffusely in low grade gliomas. In 5 patients the choline resonance decreased after radiotherapy, accompanied by a shrinkage of tumour diameter on MRI. Lactate signals were present in high grade and unspecified astrocytomas and absent in most low grade gliomas. In 3 patients the lactate signal disappeared after radiotherapy. These observations indicate the feasibility of 1H-MRS in monitoring metabolic responses on radiotherapy of brain gliomas.     

Specific MR imaging of human lymphocytes by monoclonal antibody-guided dextran-magnetite particles.

Human lymphocytes were labeled with biotinylated anti-lymphocyte-directed monoclonal antibodies, to which streptavidin and subsequently biotinylated dextran-magnetite particles were coupled. This labeling resulted in a strong and selective negative contrast enhancement of lymphocyte suspensions at 2.0 T, caused predominantly by the specific increase of R2 with a small but significant specific increase of R1. The R1 was found to decrease with increasing field strength. The immunolabeling procedure described here may be used for the selective signal depletion of target cells in MR imaging.     

FM sonography in diffuse liver disease: prospective assessment and blinded analysis

FM sonography - a signal-processing technique that uses frequency and phase information as well as amplitude data - shows promise in evaluation of patients with diffuse liver disease. In a prospective blinded review of 37 patients with biopsy-proved liver disease and 42 healthy volunteers, FM sonography was clearly superior to traditional amplitude-based (AM) sonography in distinguishing healthy from diseased subjects. Statistically significant differences were seen in accuracy (FM, 98.7%; AM, 84.8%), sensitivity (FM, 97.3%; AM, 70.3%), and negative predictive value (FM, 97.7%; AM, 78.8%). Our data also suggest that current FM sonographic techniques cannot differentiate among histologic findings associated with different hepatic parenchymal abnormalities. It is unclear, therefore, whether FM imaging can reduce the numbers of patients who require biopsy for diagnosis or the frequency of biopsy procedures in patients with known disease.     

The relationship between maternal serum zinc levels during pregnancy and birthweight

A retrospective follow-up study to ascertain the relationship between the level of serum zinc and its rate of change during gestation and birthweight was conducted in 476 women of lower socioeconomic status. Serum zinc concentrations measured at approximately 16 (early) and 32 weeks (later) in gestation were both found to be significant predictors of birthweight. Even after controlling for gestational age at birth and other determinants of birthweight, for each microgram/dl increase in serum zinc early and later in pregnancy, birthweight increased by 5.8 and 8.6 g, respectively. Furthermore, after adjustment for initial zinc levels both the total change (beta = -7.0, P = 0.0007) and the rate of change (beta = -60.8, P = 0.007) in serum zinc during pregnancy were inversely associated with birthweight, i.e., the larger the fall in serum zinc during pregnancy, the smaller the infant. Low serum zinc level (less than 60 micrograms/dl) late in pregnancy was associated with greater than a five-fold increase in the odds (OR = 5.8, 95% CI = 1.8, 16.4) of giving birth to a low birthweight infant. The results of this study suggest a threshold for maternal serum zinc below which the prevalence of low birthweight increases rapidly.