Impact of laryngeal mask airway and tracheal tube on pulmonary function during the early postoperative period

BACKGROUND

The tracheal tube (TT) produces reversible bronchoconstriction and increases pulmonary airway resistance compared to the laryngeal mask airway (LMA). The possible persistence of this effect in the postoperative period has not been studied. The aim of this study was to compare the early postoperative pulmonary function in healthy patients undergoing minor surgical procedures with the LMA or with the TT.

METHODS

Sixty patients scheduled for saphenous vein stripping under general anaesthesia were randomised to receive the LMA or the TT. Before anaesthesia and 20 min after LMA or TT removal, pulse oxymetry values (SpO(2)) were recorded and patients performed forced spirometry in the supine position.

RESULTS

Preoperative pulmonary function was normal in both groups. There were no differences between groups in the preoperative respiratory function test and SpO(2). Following surgery SpO(2), forced expiratory volume in the first second (FEV1), forced vital capacity (FVC) and peak expiratory flow (PEF) decreased in both groups. The FEV1/FVC did not change in either of the groups. In the TT group, compared to patients using the LMA, there was a greater relative decrease of SpO(2) (2.7 +/- 2.7% vs. 1.3 +/- 2.2%, P=0.017), FEV1 (17.6 +/- 12.2% vs. 8 +/- 17.4%, P=0.008), FVC (15.8 +/- 12.4% vs. 9 +/- 13.4%, P=0.023) and PEF (20.6% +/- 15.3% vs. 8.1 +/- 33.3%, P=0.033).

CONCLUSIONS

This study demonstrates greater early postoperative respiratory restrictive syndrome and lower arterial oxygen saturation following tracheal intubation compared to LMA use in patients without respiratory disease.

Pressure controlled versus volume controlled ventilation with laryngeal mask airway

STUDY OBJECTIVE

To quantify the impact on peak airway pressure of pressure-controlled and volume-controlled ventilation during Laryngeal Mask Airway (LMA) use.

DESIGN

Prospective, crossover clinical study.

SETTING

University-affiliated hospital.

PATIENTS

32 ASA physical status I and II patients undergoing general anesthesia with the LMA.

INTERVENTIONS

Patients were ventilated for three minutes both with pressure-controlled and volume-controlled ventilation, provided that tidal volume (V(T) ) and inspiratory time (It) were constant.

MEASUREMENTS AND MAIN RESULTS

The monitored parameters were electrocardiography, arterial blood pressure, pulse oximetry, capnography, neuromuscular transmission, airway pressure and flow, and concentration of ventilated vapors and gases. The actually delivered V(T) was similar with both types of ventilation (volume-controlled = 0.67 +/- 0.13 lt, pressure-controlled = 0.67 +/- 0.14 lt; p = 0.688). Peak airway pressure was lower during pressure-controlled ventilation (14.6 +/- 3.5 cmH(2)O) than during volume-controlled ventilation (16 +/- 4 cmH(2)O) (p < 0.001). Furthermore, we noted that the higher the airway pressure with volume-controlled ventilation, the greater was the reduction in airway pressure during pressure-controlled ventilation.

CONCLUSIONS

Pressure-controlled rather than volume-controlled ventilation can improve the effectiveness of mechanical ventilation in patients with high airway pressure.

Optimal decision boundaries for M-QAM signal formats using neural classifiers

The application of neural classifiers for providing optimal decision boundaries of a warped and clustered M-QAM constellation affected by nonlinearity is analyzed in this paper. The classifier behavior, for the specific application, has been evaluated both by the carrier to noise ratio (CNR) degradation (DeltaC/N) due to nonlinearity for a target error rate P(c)=10(-3), and more thoroughly by classical figures of merit of the pattern recognition theory such as classification confidence and generalization capability. The influence of the probability distribution of the training examples and the effects of activation functions' sharpness (namely the temperature of the net) have also been investigated. The results, obtained on a simulation basis, indicate optimal matching with respect to upper bounds evaluated with some minor simplifying hypothesis, even if the overall method's effectiveness can be adequate only for mild nonlinearity conditions.

[Metabolic tolerance of isradipine. Evaluation after three months of therapy]

The aim of the present study was to evaluate efficacy on blood pressure values and metabolic tolerability of Isradipine, which was given to 15 mild hypertensive non diabetic subjects (average age 63.8 +/- 10.9 years), at the dosage of 5 mg once a day. Plasma lipids concentrations and oral glucose tolerance test (OGGT) with plasma insulin assay were carrid out before, after one and three months of therapy. The statistical analysis was done using the Student's t test for paired data. Isradipine showed a good efficacy on lowering high blood pressure. In no patients the drug induced impaired glucose tolerance. Isradipine had contrasting, but not statistically significant effects on lipid concentrations, namely, decrease of triglycerides, increased of any form of cholesterol (total, HDL, LDL), apoproteins and lipoprotein(a).

Expression of cell cycle-dependent genes and proliferative state of lymphocytes in aging

The authors analyzed the expression of some genes involved in the control of T lymphocyte proliferation in a group of healthy elderly subjects. They focused their attention on genes involved in the G(0)/G(1) transition (TK, PCNA, H3, IL2-R) and showed decreased expression in the TK, H3 and IL2-R genes. Using flow cytofluorimetry, delayed transition from the G(0)/G(1) to the S stage was observed.

Vitamin E deficiency alters the in vivo Rb+ discrimination of rat brain cortical cells

The in vivo Rb+ uptake and release of rat brain cortical cells of 11-months-old rats fed with a vitamin E deficient diet was investigated. The animals were treated with a daily dose of 30 mg RbCl/100 g body weight for 14 days. After discontinuation of the RbCl treatment the animals were killed at intervals of 2, 4, 9 and 15 days, respectively. The intracellular Rb+ and K+ contents were analyzed by energy dispersive X-ray microanalysis, whereas concentrations of these two ions were determined by atomic absorbtion spectrophotometry in the serum and cerebrospinal fluid. Vitamin E deficient rats accumulate more Rb+ than age-matched normally fed animals at any time taken into account. Rb+-discrimination ratios calculated on the basis of Rb+ and K+ contents of both, cortical cell cytoplasm and cerebrospinal fluid, are higher in vitamin E deficient rats than in the controls (+20%), which supports the view that the enhanced membrane lipid peroxidation induced by vitamin E deficiency impairs the passive membrane permeability for Rb+ (and K+).

Complement and its fractions (C3-C4) pattern in subjects with neoplasia

The total complement (CH50) and its fractions C3 and C4 have been assayed for up to two years after surgery in subjects with breast, gastric and colon-rectum carcinomas. In all three types of pathology a constant pattern has been observed. Before surgery the CH50 stayed below the normal range but was increased following surgery. After a month it was again within the normal range and subsequently, according to the clinical evolution of the disease, it remained normal in those patients without relapse or any apparent metastasis, whereas in those patients who displayed metastasis and/or approached the terminal phase it fell below the normal range. The C3 fraction followed the CH50 pattern whereas the C4 did not show any variation correlated with the stages of the disease.

"In vivo" anti-hCG antibodies and Yoshida's tumor development

The anti-hCG antibodies, obtained from the rats immunized with hCG and tetanus toxoid causes slight delay in the formation of ascites liquid and increase of the survival rate in various groups of rats transplanted with Yoshida's tumor.

Effect of immunization against human chorionic gonadotropin (hCG) on transplantation of Yoshida ascitic tumour

The human chorionic gonadotropin (hCG) is considered a marker of DNA derepression on neoplastic cells. The human chorionic gonadotropin antibodies (anti-hCG antibody) inhibit the growth of yoshida tumour cells in preimmunized recipient rats. A close relationship between the anti-hCG antibodies and tumour cell transplantation has been observed. This relationship and further experimental implications are briefly discussed.

In vitro lymphocyte sensitivity test to methisoprinol in different pathological conditions

The present paper describes an in vitro study with Methisoprinol, carried out by means of various lymphocyte sensitivity tests in different pathological conditions. Methisoprinol does not exert any effect--neither on responsiveness nor on lymphocyte function--in healthy subjects, while in subjects with immunodepressive pathology the drug is capable of increasing these parameters either alone (rosettes) or in conjunction with mitogens (rosetting) at doses between 50 and 100 micrograms/ml.

[Changes in the membrane receptors of lymphocyte populations during immunization]

A population of splenic lymphocytes has been studied as well as their surface antibodies and their affinity for antigen in different days and periods of immunization. Fractionation of a specific population of lymphocytes having an affinity for antigens coated on glass beads were accomplished. The other aspecific population did not bind ot the glass beads and was not retained on the column. During the primary immuno-response the number of lymphocytic cells with surface antibodies specific for antigen was higher than in the booster response: in secondary response only the total number of antibody forming-cells increases while the number of lymphocytes with surface antibodies is constant. The authors suppose that the surface of spleen lymphocytes is modificated in different way at different time, by immunizing antigen.

Localization of polypeptides in frog virus 3 by radioiodination technique

Frog virus 3 is an amphibian icosahedral deoxyribovirus which replicates in the cytoplasm of infected cells. The radioiodination of purified virions using the enzyme lactoperoxidase has shown that the major component of the structural proteins is only partially exposed through the lipoprotein membrane that constitutes the outer layer of the icosahedral capsid.

Polypeptide analysis of a "Leishmania donovani" strain isolated during an outbreak of visceral leishmaniasis in northern Italy

The results of the analysis of the polypeptide composition of a strain of Leishmania donovani isolated during an outbreak of kala azar in northern Italy are reported.

Evidence for somatic generation of antibody diversity

RNA preparations containing 70-80% mouse kappa-chain mRNA have been prepared. The remainder consists of many RNA species, each of which represents a small fraction of the total RNA. The kappa-chain mRNA preparation hybridizes with mouse liver DNA with bi-phasic kinetics, indicating that it consists of two fractions -"unique" and "reiterated." Competition hybridization experiments show that the homology among the unique fractions from different mRNAs is the same as the homology among the amino acid sequences of the corresponding kappa-chains. Hence, in addition to the C-region (constant-region) sequences, (most of) the V-region (variable-region) sequences are also derived from unique germ line genes. The reiterated fractions from different kappa-chain mRNAs show essentially complete homology with each other. This fraction seems to consist mostly of sequences which do not code for amino-acid sequences of the secreted polypeptide chain, i.e., the "external" section of the mRNA molecule. It is concluded that the number of germ line genes is too small to account for the observed diversity of antibody molecules.

Induction of antibody synthesis. Effect of blocking defined determinants of an antigen

Rabbit antibody specific for bovine γ-globulin (BGG) and for the dinitrophenyl group (DNP) was used to block defined determinants of BGG—DNP, and the immunogenicity of antibody-complexed BGG—DNP in rabbits was compared with that of BGG—DNP. Antibody-complexed BGG—DNP was less immunogenic, eliciting less antibody reactive with BGG—DNP. However, BGG-specific antibody, in contrast to DNP-specific antibody, suppressed primarily the induction of antibody specific for the BGG determinants of BGG—DNP. This finding suggests: (1) that induction of antibody specific for a given determinant of an antigen requires the active participation of that determinant as an inducer, and (2) that the immunosuppressive action of antibody is determinant-specific and not antigen-specific. The immunogenicity of antibody-complexed sheep erythrocytes was also studied in mice. Rabbit antibody to sheep erythrocytes, in different amounts, was used to block determinants on the surface of sheep erythrocytes. The agglutinin response was inversely proportional to the amount of antibody used to complex the erythrocytes. This finding supports the role of determinants as inducers of antibody formation and indicates that the immunogenicity of an antigen is a function of the number of determinants it carries in an accessible reactive state.