Pere Casan

N-terminal probrain natriuretic peptide (NT-proBNP) in the emergency diagnosis and in-hospital monitoring of patients with dyspnoea and ventricular dysfunction.

To evaluate the utility of NT‐proBNP in the emergency diagnosis and in‐hospital monitoring of patients with acute dyspnoea and ventricular dysfunction.

PREDICTION EQUATIONS FOR PLETHYSMOGRAPHIC LUNG VOLUMES

Due to the lack of information of reference values for plethysmographic lung volumes, standardized measurements were carried out on a selected sample of 482 healthy non-smoking volunteers (300 men and 182 women), aged 20-70 years, living in the Barcelona area (Spain). Prediction equations using age, height and body surface area (BSA) as covariates were calculated for the subdivisions of lung volumes [TLC, IC, EVC, FRC, RV and RV/TLC (%)], separately for both sexes. Simple linear equations predicted lung volumes as well as more complex equational models. BSA correction was useful for FRC but not for the other parameters. Our predicted FRC was up to 10% higher (mean 256 ml) than the FRC estimated by other studies using gas dilution techniques, but showed an acceptable agreement with the plethysmographic measurements carried out in an independent sample of 94 healthy non-smokers (42 men and 52 women) from Barcelona using different equipment. The present study provides an internally consistent set of prediction equations for static lung volumes. Differences in predicted FRC between the present study and other reference values obtained using gas dilution measurements should be attributed to the method of measurement.

Use of electrical impedance tomography (EIT) for the assessment of unilateral pulmonary function

We describe a fully automatable quantification process for the assessment of unilateral pulmonary function (UPF) by means of EIT and propose a measurement protocol for its clinical implementation. Measurements were performed at the fourth and sixth intercostal levels on a first group of ten healthy subjects (5M, 5F, ages 26-48 years) to define the proper protocol by evaluating the most common postures and ventilation modes. Several off-line processing tools were also evaluated, including the use of digital filters to extract the respiratory components from EIT time series. Comparative measures were then carried out on a second group consisting of five preoperatory patients with lung cancer (4M, IF, ages 25-77 years) scheduled for radionuclide scanning. Results show that measurements were best performed with the subject sitting down, holding his arms up and breathing spontaneously. As regards data processing, it is best to extract Fourier respiratory components. The mean of the healthy subject group leads to a left-right division of lung ventilation consistent with literature values (47% left lung, 53% right lung). The comparative study indicates a good correlation (r = 0.96) between the two techniques, with a mean difference of (-0.4+/-5.4)%, suggesting that the elimination of cardiac components from the thoracic transimpedance signal leads to a better estimation of UPF.

Airway and alveolar nitric oxide measurements in obstructive sleep apnea syndrome.

STUDY OBJECTIVES The process of intermittent hypoxia-reoxygenation produces airway inflammation and endothelial dysfunction that favors the development of cardiovascular disorders in obstructive sleep apnea syndrome (OSAS). Nitric oxide (NO) is an important mediator in airway inflammation and the regulation of endothelium-dependent vasodilation. DESIGN This study compared airway NO (FE(NO)) and alveolar NO (CA(NO)) measurements in exhaled breath in 30 OSAS patients to those of 30 healthy (non-OSAS) individuals and determined the relationship between NO levels and OSAS severity. Additionally, NO measurements were analyzed after 3 months of CPAP treatment. MEASUREMENTS AND RESULTS The mean (±SD) FE(NO) level in the OSAS group (27.2 ± 18 ppb) was higher than in the healthy non-OSAS group (p = 0.006). The mean CA(NO) level was 1.65 ± 0.90 ppb, lower than in the non-OSAS group (p = 0.001). A significant correlation was found between FE(NO) and CA(NO) levels and the apnea-hypopnea index (AHI) in the OSAS group (r = 0.8, p < 0.05; r = -0.9, p = 0.01, respectively). FE(NO) levels decreased and CA(NO) levels increased significantly after CPAP treatment. CONCLUSIONS Severe OSAS patients have higher FE(NO) and lower CA(NO) levels and these are restored to normal after CPAP treatment, reflecting the correction of local upper airway inflammation and endothelial dysfunction present in OSAS patients. Exhaled breath techniques can be useful to identify airway inflammation and endothelial dysfunction in severe OSAS patients.

Effects of halothane and isoflurane on ventilation and occlusion pressure.

Isoflurane has been said to be more ventilatory depressant than halothane. However, data for comparing the respiratory effects of halothane and isoflurane in humans are insufficient at this time. The aim of this study was to extend our understanding of the nature of the central, as opposed to peripheral, ventilatory effect of halothane and isoflurane by comparing them at two concentrations. Methods:Twenty patients were randomly assigned to receive halothane (n=10) or isoflurane (n=10). The patients were studied the day before surgery and during anesthesia immediately before surgery. Ventilatory effects were analyzed in terms of breathing pattern, end-tidal carbon dioxide pressure (PETCO2) and inspiratory occlusion pressure. After anesthetic induction and orotracheal intubation with thiopental and succinylcholine patients were allowed to breathe halothane or isoflurane in oxygen spontaneously at 1.2 (low) and 2.0 (high) minimum alveolar concentration (MAC) applied in random order. Inspiratory active impedance during anesthesia was also measured. Results:Significant reduction of minute ventilation between awake and low MAC states was observed for isoflurane (-34.4%; P<0.001) but not for halothane. Inspiratory occlusion pressure at 100 ms increased significantly between awake and low MAC states, from 1.43 ± 0.89 to 2.67 ± 1.05 cmH2O (P<0.05) for halothane, representing an 87% increase, whereas a nonsignificant increase (16%) was observed for isoflurane. Both anesthetics showed a dose-related ventilatory depressant effect, not attributable to changes in mechanical properties, reflected by significant reductions in minute ventilation (P<0.001), tidal volume (P<0.001), and inspiratory occlusion pressure at 100 ms (P<0.05) and increases in respiratory rate (P<0.001) and end-tidal carbon dioxide pressure (P<0.01) when concentration was increased. However, at the higher concentration a significantly greater reduction of minute ventilation (P<0.01) was observed for isoflurane (-25.6%) than for halothane (-9.4%). We did not observe differences in respiratory rate between the two anesthetics. Significant differences in inspiratory occlusion pressure wave were observed, characterized by a concave-upward tendency for isoflurane and for high concentration. Conclusions:Our study confirms the stronger ventilatory depression induced by isoflurane compared with that induced by halothane and indicates that halothane at 1.2 MAC induces significantly less ventilatory depression than expected.

Factores de riesgo de mortalidad en la EPOC

Objetivo Aunque los factores que predicen la supervivencia en pacientes con enfermedad pulmonar obstructive cronica (EPOC) han sido ampliamente estudiados, no disponemos de un consenso establecido. El objetivo de este estudio ha sido contribuir a clarificar el papel que desempenan los parametros de funcion pulmonar, tolerancia al esfuerzo y calidad de vida en la supervivencia en la EPOC. Pacientes y metodos Se diseno un estudio prospectivo en el que se incluyo a 60 pacientes diagnosticados de EPOC. Al inicio del estudio realizaron pruebas funcionales respiratorias, prueba de esfuerzo maximo y prueba de la marcha de 6 min, y respondieron un cuestionario de enfermedad respiratoria cronica para determinar la calidad de vida relacionada con la salud. El seguimiento de los pacientes fue de 7 anos. Resultados Se retiraron del estudio 5 de los 60 pacientes. De los 55 restantes, 26 (47%) murieron durante el estudio. El analisis univariante con regresion de Cox mostro que existia relacion entre la supervivencia y la edad, el grado de obstruccion, la capacidad inspiratoria, la capacidad de difusion del monoxido de carbono y la tolerancia al ejercicio maximo; no se observo dicha relacion entre la supervivencia y el indice de masa corporal, la presion arterial de oxigeno y anhidrido carbonico, la capacidad pulmonar total, el volumen residual, las presiones maximas respiratorias, la prueba de la marcha de 6 min ni la calidad de vida relacionada con la salud. En el analisis multivariante con regresion de Cox con pasos hacia adelante, en el que se introdujeron la edad, el grado de obstruccion (medido con la relacion volumen espiratorio forzado en el primer segundo/capacidad vital forzada tras la administracion de broncodilatador) y la ventilacion minuto maxima en la prueba de esfuerzo, solo esta ultima entro en el modelo final (riesgo relativo = 0,926; p Conclusiones Nuestros hallazgos demuestran que la tolerancia al ejercicio maximo es el mejor predictor de supervivencia en los pacientes con EPOC.

Determinación de óxido nítrico en aire espirado (FENO) mediante un equipo portátil (NIOX-MINO® Aerocrine) en población sana

La determinacion de oxido nitrico en aire espirado (FENO) es una tecnica no invasiva que se utiliza en la evaluacion clinica y el tratamiento del asma. El objetivo de este estudio ha sido determinar los valores de referencia de FENO en un grupo de voluntarios sanos mediante la utilizacion de un nuevo equipo portatil (NIOX-MINO® Aerocrine), asi como determinar el grado de relacion que presenta con el equipo de determinacion habitual en nuestro laboratorio de funcion pulmonar (sensor de quimioluminiscencia N-6008® SIR). Segun los resultados obtenidos, los valores de FENO que da el equipo portatil son siempre superiores a los que ofrece el sensor habitual, con un valor de corte de 34 ppb (media + 2 desviacion estandar). Existe un relacion directa y significativa de la determinacion de FENO entre ambos equipos (r = 0,92; p = 0,001) con un factor de correccion de: FENO (NIOX-MINO®) = 10 + 1,5 FENO (N-6008®). La relacion entre los valores de FENO y la edad, el sexo, el indice de masa corporal y los valores espirometricos no fue estadisticamente significativa.

Evaluation of Dysphonia in a Children’s Choir

This study isolates the voice problems of 99 (40 male, 59 female) children choir singers (age range: 8-14), by applying and validating a simple method for classifying the singing voice. The prevalence of dysphonia was 20.2%. A singing range of fewer than 18 semitones is considered to suggest dysphonia (sensitivity of 80% and specificity of 95%). The validity of the method and its ease of application are discussed. We conclude that voice classification is necessary for all children who sing and that phoniatric examination of dysphonic children is imperative, with special attention given to those whose voices are changing.

Measuring Breathing Pattern in Patients With Chronic Obstructive Pulmonary Disease by Electrical Impedance Tomography

a b s t r a c t Background and Objective: The measurement of breathing pattern in patients with chronic obstructive pulmonary disease (COPD) by electrical impedance tomography (EIT) requires the use of a mathematical calibration model incorporating not only anthropometric characteristics (previously evaluated in healthy individuals) but probably functional alterations associated with COPD as well. The aim of this study was to analyze the association between EIT measurements and spirometry parameters, static lung volumes, and carbon monoxide diffusing capacity (DLCO) in a group of male patients to develop a calibration equation for converting EIT signals into volume signals. Materials and Methods: We measured forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), FEV1/FVC, residual volume, total lung capacity, DLCO, carbon monoxide transfer coefficient (KCO) and standard anthropometric parameters in 28 patients with a FEV1/FVC ratio of <70%. We then compared tidal volume measurements from a previously validated EIT unit and a standard pneumotachometer. Results: The mean (SD) lung function results were FVC, 72 (16%); FEV1, 43% (14%); FEV1/FVC, 42% (9%); residual volume, 161% (44%); total lung capacity, 112% (17%); DLCO, 58% (17%); and KCO, 75% (25%). Mean (SD) tidal volumes measured by the pneumotachometer and the EIT unit were 0.697 (0.181) L and 0.515 (0.223) L, respectively (P<.001). Significant associations were found between EIT measurements and CO transfer parameters. The mathematical model developed to adjust for the differences between the 2 measurements (R 2 =0.568; P<.001) was compensation factor=1.81 - 0.82 × height (m) - 0.004×KCO (%). Conclusions: The measurement of breathing pattern by EIT in patients with COPD requires the use of a previously calculated calibration equation that incorporates not only individual anthropometric characteristics but gas exchange parameters as well.

Sistemas de ahorro de oxígeno. Una realidad olvidada

Los sistemas de ahorro de oxigeno agrupan el cateter transtraqueal, las canulas reservorio y los sistemas a demanda. Su objetivo es aumentar la autonomia de las fuentes de oxigeno portatiles consiguiendo una correccion de la hi-poxemia con menor flujo de oxigeno. El cateter transtraqueal aumenta la fraccion inspiratoria de oxigeno al proporcionar oxigeno directamente en la traquea, lo que evita el espacio muerto de la cavidad orofaringea y favorece que la via aerea superior actue como reservorio. Las canulas reservorio aumentan la fraccion inspiratoria de oxigeno al inicio de la inspiracion. Los sistemas a demanda cuentan con una valvula que se activa con la inspiracion, de modo que se administra oxigeno solo durante esta fase del ciclo respiratorio. Debido a sus diferentes caracteristicas, cada sistema presenta ventajas e inconvenientes. Para su correcta prescripcion debe ajustarse individualmente el flujo de oxigeno tanto en reposo como durante el ejercicio o el sueno con las pruebas pertinentes.