Efeitos da pressão limite (25 cmH2O) e mínima de "selo" do balonete de tubos traqueais sobre a mucosa traqueal do cão

JUSTIFICATIVA E OBJETIVOS: As lesões da mucosa traqueal em contato com o balonete do tubo traqueal são proporcionais à pressão exercida pelo balonete e ao tempo de exposição. O objetivo foi estudar as eventuais lesões da mucosa do segmento traqueal em contato com o balonete do tubo traqueal insuflado com volume de ar suficiente para se obter pressão de "selo" ou com a pressão limite de 25 cmH2O, abaixo da pressão crítica de 30 cm de água para produção de lesão da mucosa traqueal. MÉTODO: Dezesseis cães foram submetidos à anestesia venosa e ventilação artificial. Os cães foram distribuídos aleatoriamente em dois grupos de acordo com a pressão no balonete do tubo traqueal (Portex Blue-Line, Inglaterra): Gselo (n = 8) balonete com pressão mínima de "selo" para impedir vazamento de ar durante a respiração artificial; G25 (n = 8) balonete insuflado até obtenção da pressão de 25 cmH2O. A medida da pressão do balonete foi realizada por meio de manômetro digital no início (controle) e após 60, 120 e 180 minutos. Após o sacrifício dos cães, foram feitas biópsias nas áreas da mucosa traqueal adjacentes ao balonete e ao tubo traqueal para análise à microscopia eletrônica de varredura (MEV). RESULTADOS: A pressão média do balonete em G25 manteve-se entre 24,8 e 25 cmH2O e em Gselo entre 11,9 e 12,5 cmH2O durante o experimento. As alterações à MEV foram pequenas e não significantemente diferentes nos grupos (p > 0,30), mas ocorreram lesões mais intensas nas áreas de contato da mucosa traqueal com o balonete do tubo traqueal, nos dois grupos, em relação às áreas da mucosa adjacentes ou não ao tubo traqueal (p < 0,05). CONCLUSÕES: No cão, nas condições experimentais empregadas, a insuflação do balonete de tubo traqueal em volume de ar suficiente para determinar pressão limite de 25 cmH2O ou de "selo" para impedir vazamento de ar determina lesões mínimas da mucosa traqueal em contato com o balonete e sem diferença significante entre elas.

Effectiveness and safety of endotracheal tube cuffs filled with air versus filled with alkalinized lidocaine: a randomized clinical trial

CONTEXTO E OBJETIVO: Os tubos traqueais são dispositivos utilizados para manutenção da ventilação. A hiperinsuflação do balonete do tubo traqueal, causada pela difusão do óxido nitroso (N2O), pode determinar lesões traqueais, que se manifestam clinicamente como odinofagia, rouquidão e tosse. A lidocaína, quando injetada no balonete do tubo traqueal, difunde-se através de sua parede, determinando ação anestésica local na traquéia. O objetivo foi avaliar a efetividade e a segurança do balonete do tubo traqueal preenchido com ar comparado com o balonete preenchido com lidocaína, considerando os desfechos: sintomas cardiovasculatórios (HAS, taquicardia); odinofagia, tosse, rouquidão e tolerância ao tubo traqueal. TIPO DE ESTUDO E LOCAL: Estudo clínico prospectivo, realizado no Departamento de Anestesiologia da Faculdade de Medicina da Unesp, campus de Botucatu. MÉTODOS: A pressão do balonete do tubo traqueal foi medida, entre 50 pacientes, antes, 30, 60, 90 e 120 minutos após o início da inalação de N2O anestésico. As pacientes foram distribuídas aleatoriamente em dois grupos: Air, em que o balonete foi inflado com ar para obtenção de pressão de 20 cm H2O, e Lido, em que o balonete foi preenchido com lidocaína a 2% mais bicarbonato de sódio a 8,4% para obtenção da mesma pressão. O desconforto antes da extubação, e manifestações clínicas como dor de garganta, rouquidão e tosse foram registrados no momento da alta da unidade de cuidados pós-anestésicos, e dor de garganta e rouquidão foram avaliadas também 24 horas após a anestesia. RESULTADOS: Os valores da pressão no balonete em G2 foram significativamente menores do que os de Air em todos os tempos de estudo, a partir de 30 minutos (p < 0,001). A proporção de pacientes que reagiu ao tubo traqueal no momento da desintubação foi significantemente menor em Lido (p < 0,005). A incidência de odinofagia foi significantemente menor em Lido no primeiro dia de pós-operatório (p < 0,05). A incidência de tosse e rouquidão não diferiu entre os grupos. CONCLUSÕES: Durante ventilação artificial, empregando-se a mistura de oxigênio e N2O, a insuflação do balonete com lidocaína 2% alcalinizada impede que ocorra aumento significante da pressão no balonete e determina maior tolerância ao tubo traqueal e menor incidência de odinofagia no pós-operatório, podendo então ser considerada mais segura e com maior efetividade.

Myocardial dysfunction with increased ventricular compliance in volume overload hypertrophy

The aim this study was to evaluate systolic and diastolic function in volume overload induced myocardial hypertrophy in rats.Volume overload myocardial hypertrophy was induced in thirteen male Wistar rats by creating infrarenal arteriovenous fistula (AVF). The results were compared with a SHAM operated group (n = 11). Eight weeks after surgery, tail-cuff blood pressure was recorded, then rats were sacrificed for isolated heart studies using Langendorffs preparation.AVF rats presented increased left and right ventricular weights, compared to controls. The increased normalized ventricular volume (V0/LVW, 0.141 +/- 0.035 mL/g vs. 0.267 +/- 0.071 mL/g, P < 0.001) in the AVF group indicated chamber dilation. Myocardial hydroxyproline concentration remained unchanged. There was a significant decrease in +dP/dt (3318 +/- 352 mm Hg s(-1) vs. 2769 +/- 399 mm Hg s(-1); P=0,002), end-systolic pressure-volume relation (246 +/- 56 mm Hg mL(-1) vs. 114 +/- 63 mm Hg mL(-1);, P < 0,001), and -dP/dt (1746 +/- 240 min Hg s(-1) vs. 1361 +/- 217 mm Hg s(-1), P < 0.001) in the AVF group, which presented increased ventricular compliance (Delta V-25: SHAM=0.172 +/- 0.05 mL vs. AVF=0.321 +/- 0.072 mL, P < 0.001) with preserved myocardial passive stiffness (Strain(25): SHAM=13.5 +/- 3.0% vs. AVF=12.3 +/- 1.9%, P > 0.05).We conclude that volume-overload induced hypertrophy causes myocardial systolic and diastolic dysfunction with increased ventricular compliance. These haemodynamic features help to explain the long-term compensatory phase of chronic volume overload before transition to overt congestive heart failure. (c) 2006 European Society of Cardiology. Published by Elsevier B.V. All rights reserved.

Effects of hypertension on maternal adaptations to pregnancy: experimental study on spontaneously hypertensive rats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Effect of felodipine on myocardial and renal injury induced by aldosterone-high salt hypertension in uninephrectomized rats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Remodelação miocárdica na sobrecarga crônica de pressão ou de volume no coração de ratos

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effects of buprenorphine, carprofen and saline on thermal and mechanical nociceptive thresholds in cats

To evaluate a prototype pressure stimulus device for use in the cat and to compare with a known thermal threshold device.Eight healthy adult cats weighing between 3.0 and 4.9 kg.Pressure stimulation was given via a plastic bracelet taped around the forearm. Three 2.4 mm diameter ball bearings, in a 10-mm triangle, were advanced against the craniolateral surface of the antebrachium by manual inflation of a modified blood pressure bladder. Pressure in the cuff was recorded at the end point (leg shake and head turn). Thermal threshold was also tested. Stimuli were stopped if they reached 55 degrees C or 450 mmHg without response. After four pressure and thermal threshold baselines, each cat received SC buprenorphine 0.01 mg kg(-1), carprofen 4 mg kg(-1) or saline 0.3 mL in a three period cross-over study with a 1-week interval. The investigator was blinded to the treatment. Measurements were made at 0.25. 0.5, 0.75, 1, 2, 3, 4, 6, 8, and 24 hours after injection. Data were analyzed by using ANOVA.There were no significant changes in thermal or pressure threshold after administration of saline or carprofen, but thermal threshold increased from 60 minutes until 8 hours after administration of buprenorphine (p < 0.05). The maximum increase in threshold from baseline (Delta T-max) was 3.5 +/- 3.1 degrees C at 2 hours. Pressure threshold increased 2 hours after administration of buprenorphine (p < 0.05) when the increase in threshold above baseline (Delta P-max) was 162 +/- 189 mmHg.This pressure device resulted in thresholds that were affected by analgesic treatment in a similar manner but to a lesser degree than the thermal method. Pressure stimulation may be a useful additional method for analgesic studies in cats.

Protective effects of carvedilol on systemic vascular damage induced by angiotensin II: Organ-specific effects independent of antihypertensive effects

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comparative scanning electron microscopic study of the effect of different dental conditioners on dentin micromorphology

This study evaluated comparatively by scanning electron microscopy (SEM) the effect of different dental conditioners on dentin micromorphology, when used according to the same protocol. Forty dentin sticks were obtained from 20 caries-free third human molars and were assigned to 4 groups corresponding to 3 conditioners (phosphoric acid 37%, Clearfil SE Bond and iBond) and an untreated control group. After application of the conditioners, the specimens were immersed in 50% ethanol solution during 10 s, chemically fixed and dehydrated to prepare them to SEM analysis. In the control group, dentin surface was completely covered by smear layer and all dentinal tubules were occluded. In the phosphoric acid-etched group, dentin surface was completely clean and presented exposed dentinal tubule openings; this was the only group in which the tubules exhibited the funnel-shaped aspect. In the groups conditioned with Clearfil SE Bond primer and iBond, which are less acidic than phosphoric acid, tubule openings were occluded or partially occluded, though smear layer removal was observed. SE Bond was more efficient in removing the smear layer than iBond. In the Clearfil SE Bond group, the cuff-like aspect of peritubular dentin was more evident. It may be concluded all tested conditioners were able to change dentin morphology. However, it cannot be stated that the agent aggressiveness was the only cause of the micromorphological alterations because a single morphological pattern was not established for each group, but rather an association of different aspects, according to the aggressiveness of the tested conditioner.

Statistical properties of a dissipative kicked system: Critical exponents and scaling invariance

A new universal empirical function that depends on a single critical exponent (acceleration exponent) is proposed to describe the scaling behavior in a dissipative kicked rotator. The scaling formalism is used to describe two regimes of dissipation: (i) strong dissipation and (ii) weak dissipation. For case (i) the model exhibits a route to chaos known as period doubling and the Feigenbaum constant along the bifurcations is obtained. When weak dissipation is considered the average action as well as its standard deviation are described using scaling arguments with critical exponents. The universal empirical function describes remarkably well a phase transition from limited to unlimited growth of the average action. (C) 2012 Elsevier B.V. All rights reserved.

The effect of intracuff alkalinized 2% lidocaine on emergence coughing, sore throat, and hoarseness in smokers

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Development of a pressure nociceptive threshold testing device for evaluation of analgesics in cats

A pressure analgesiometric device was developed for unrestrained cats. Eleven cats were studied. Stimulation was via three rounded pins within a bracelet on the forearm. The pins were advanced by manual bladder inflation. Bladder pressure was measured using a strain gauge pressure transducer. The threshold was recorded at the behavioural end point. Thresholds were measured at 5 and 15 min intervals for 2-4 h, after removal/replacement of the cuff, for 120 min after SC butorphanol (0.4 mg/kg), and with mild skin inflammation at the testing site. Data were analysed using ANOVA. Pressure thresholds in untreated cats were around 150 mmHg. The minimum interval for testing was established as 15 min. Data were reproducible over 4 h and beyond 24 h. Thresholds in 5 cats increased (P < 0.05) above baseline for 45 min after butorphanol with a maximum increase of 270 +/- 182 mmHg at 10 min. Thresholds decreased with inflammation. The method appears suitable for feline analgesia investigations. (c) 2006 Elsevier Ltd. All rights reserved.

Effect of high laryngeal mask airway intracuff pressure on the laryngopharyngeal mucosa of dogs

Objectives: To evaluate the effect of increased of laryngeal mask airway (LMA) intracuff pressures on the laryngopharyngeal mucosa. Study Design: Animal model. Methods: Sixteen mixed-breed dogs were randomly allocated to two groups, G1 (intracuff volume, 30 mL; n = 8) and G2 (intracuff volume, 54 mt; n = 8), to produce, respectively, high or very high intracuff pressures. Anesthesia was induced and maintained with pentobarbital. Intracuff pressures were measured immediately after insertion and inflation of a No. 4 laryngeal mask airway (LMA) and 30, 60, 90, and 120 minutes thereafter. The dogs were euthanized, and biopsy specimens from eight predetermined areas of the laryngopharynx in contact with LMA cuff were collected for light microscopic (LM) and scanning electron microscopic (SEM) examination. Results: Initial LMA cuff inflation in G1 and G2 resulted in intracuff pressures of 119 mm Hg +/- 4 mm Hg and 235 mm Hg +/- 13 mm Hg, respectively. Over a 2-hour period, the intracuff pressure decreased significantly in G1 (P < .001) and G2 (P < .01), and there was a significant difference between the groups over time (P < .001). The LM study of laryngopharyngeal mucosa in both groups showed mild congestion in the subepithelial layer. There were no differences between the groups (P > .10) or among the areas sampled (P > .10). In some areas of G2, the SEM study showed epithelial desquamation that was more intense than that in GI. Conclusions: the increase in LMA intracuff pressure caused only mild alterations in the laryngopharyngeal mucosa of the dog.

Long-term nitric oxide inhibition and chronotropic responses in rat isolated right atria

The long-term administration of nitric oxide synthesis inhibitors induces arterial hypertension accompanied by left ventricular hypertrophy and myocardial ischemic lesions. Because the enhancement of sympathetic drive has been implicated in these phenomena, the current study was performed to determine the potency of β-adrenoceptor agonists and muscarinic agonists on the spontaneous rate of isolated right atria from rats given long-term treatment with the nitric oxide inhibitor N(ω)-nitro-L-arginine methyl ester (L-NAME). Atrial lesions induced by long-term treatment with L-NAME were also evaluated. Long-term L-NAME treatment caused a time-dependent, significant (P<0.05) increase in tail-cuff pressure compared with control animals. Our results showed that the potency of isoproterenol, norepinephrine, carbachol, and pilocarpine in isolated right atria from rats given long-term treatment with L-NAME for 7, 15, 30, and 60 days was not affected as compared with control animals. Addition of L-NAME in vitro (100 μmol/L) affected neither basal rate nor chronotropic response for isoproterenol and norepinephrine in rat heart. Stereological analysis of the right atria at 15 and 30 days revealed a significant increase on amount of fibrous tissues in L-NAME- treated groups (27±2.3% and 28±1.3% for 15 and 30 days, respectively; P<0.05) as compared with the control group (22±1.1%). Our results indicate that nitric oxide does not to interfere with β-adrenoceptor-mediated and muscarinic receptor-mediated chronotropic responses.

Resting heart rate: Its correlations and potential for screening metabolic dysfunctions in adolescents

Background: In pediatric populations, the use of resting heart rate as a health index remains unclear, mainly in epidemiological settings. The aims of this study were to analyze the impact of resting heart rate on screening dyslipidemia and high blood glucose and also to identify its significance in pediatric populations.Methods: The sample was composed of 971 randomly selected adolescents aged 11 to 17 years (410 boys and 561 girls). Resting heart rate was measured with oscillometric devices using two types of cuffs according to the arm circumference. Biochemical parameters triglycerides, total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol and glucose were measured. Body fatness, sleep, smoking, alcohol consumption and cardiorespiratory fitness were analyzed.Results: Resting heart rate was positively related to higher sleep quality (β = 0.005, p = 0.039) and negatively related to cardiorespiratory fitness (β = -0.207, p = 0.001). The receiver operating characteristic curve indicated significant potential for resting heart rate in the screening of adolescents at increased values of fasting glucose (area under curve = 0.611 ± 0.039 [0.534 - 0.688]) and triglycerides (area under curve = 0.618 ± 0.044 [0.531 - 0.705]).Conclusion: High resting heart rate constitutes a significant and independent risk related to dyslipidemia and high blood glucose in pediatric populations. Sleep and cardiorespiratory fitness are two important determinants of the resting heart rate. © 2013 Fernandes et al.; licensee BioMed Central Ltd.