Early Use of Echocardiography in Patients With Acute Pulmonary Embolism: Findings From the RIETE Registry.

Background Transthoracic echocardiography ( TTE ) is often considered for risk stratification of patients with acute pulmonary embolism ( PE ). We sought to determine the contemporary utilization of early TTE (within 72 hours of PE diagnosis) and explored the association between TTE findings and PE -related mortality. Methods and Results Data from the RIETE (Registro Informatizado Enfermedad TromboEmbolica) registry, a multicenter registry of consecutive patients with acute PE , were used (2001-July 2017). We used a generalized linear mixed model to determine predictors of early TTE performance. Moreover, the association between 3 TTE variables (right atrial enlargement, right ventricular hypokinesis, and presence of right heart thrombi) and 30-day PE -related mortality was assessed in generalized linear mixed models adjusted for PE severity index, and other comorbidities. Among 35 935 enrollees with acute PE , 15 375 (42.8%) underwent early TTE . There was an increase in early TTE utilization rate over time ( P<0.001 for trend). Younger age, female sex, enrollment in countries other than Spain, history of coronary disease, heart failure, atrial fibrillation, tachycardia, and hypotension were the main predictors of early TTE ( P<0.01 for all). In multivariable analyses, right atrial enlargement (adjusted odds ratio: 3.74; 95% confidence interval, 2.10-6.66), right ventricular hypokinesis (adjusted odds ratio: 3.11, 95% confidence interval: 1.85-5.21) and right heart thrombi (adjusted odds ratio: 4.39, 95% confidence interval, 1.99-9.71) were associated with increased odds for PE -related mortality. Conclusions Early TTE is commonly performed for acute PE and utilization rates have increased over time. Right atrial enlargement, right ventricular hypokinesis, and right heart thrombi are predictive of worse outcomes. Clinical Trial Registration URL : http://www.clinicaltrials.gov . Unique identifier: NCT 02832245.

Impact of tobacco prices and smoke-free policy on smoking cessation, by gender and educational group: Spain, 1993-2012.

BACKGROUND: To evaluate the effect of tobacco prices and the implementation of smoke-free legislation on smoking cessation in Spain, by educational level, across the period 1993-2012. METHODS: National Health Surveys data for the above two decades were used to calculate smoking cessation in people aged 25-64 years. The relationship between tobacco prices and smoking quit-ratio was estimated using multiple linear regression adjusted for time and the presence of smoke-free legislation. The immediate as well as the longer-term impact of the 2006 smoke-free law on quit-ratio was estimated using segmented linear regression analysis. The analyses were performed separately in men and women with high and low education, respectively. RESULTS: No relationship was observed between tobacco prices and smoking quit-ratio, except in women having a low educational level, among whom a rise in price was associated with a decrease in quit-ratio. The smoke-free law altered the smoking quit-ratio in the short term and altered also pre-existing trends. Smoking quit-ratio increased immediately after the ban - though this increase was significant only among women with a low educational level - and then decreased in subsequent years except among men with a high educational level. CONCLUSION: A clear relationship between tobacco prices and smoking quit-ratio was not observed in a recent period. After the implementation of smoke-free legislation the trend in the quit ratio in most of the socio-economic groups was different from the trend observed before implementation, so existing inequalities in smoking quit-ratio were not widened or narrowed.

Predictors of advanced disease and late presentation in new HIV diagnoses reported to the surveillance system in Spain / Determinantes de enfermedad avanzada y presentación tardía en los nuevos diagnósticos de VIH notificados al sistema de vigilancia epidemiológica en España

Objective: To present surveillance data on advanced disease (AD) and late presentation (LP) of HIV in Spain and their determinants. Methods We included all new HIV diagnoses notified by the autonomous regions that consistently reported such cases throughout the period 2007-2011. Coverage was 54% of the total Spanish population. Data sources consisted of clinicians, laboratories and medical records. AD was defined as the presence of a CD4 cell count <200cells/μL in the first test after HIV diagnosis, while LP was defined as the presence of a CD4 cell count <350cells/μL after HIV diagnosis. Odds ratios and their 95% confidence intervals (OR, 95% CI) were used as the measure of association. Logistic regressions were fit to identify predictors of AD and LP. Results A total of 13,021 new HIV diagnoses were included. Among these, data on the outcome variable were available in 87.7%. The median CD4 count at presentation was 363 (interquartile range, 161-565). Overall, 3356 (29.4%) patients met the definition of AD and 5494 (48.1%) were classified as LP. Both AD and LP increased with age and were associated with male sex and infection through drug use or heterosexual contact. All immigrants except western Europeans were more prone to AD and LP. Multivariate models disaggregated by sex showed that the effect of age and region of origin was weaker in women than in men. Conclusions Despite universal health care coverage in Spain, men, immigrants and people infected through drug use or heterosexual contact seem to be experiencing difficulties in gaining timely access to HIV care (AU)

Objetivo: Se presentan los datos de vigilancia sobre enfermedad avanzada y presentación tardía de los nuevos diagnósticos de VIH en España, y sus determinantes. Métodos Se incluyeron todos los nuevos diagnósticos de VIH de 2007-2011 en el ámbito de las comunidades autónomas que notificaron de forma constante durante todo el periodo (54% de la población española). La fuente de información fueron clínicos y laboratorios. Se definió como enfermedad avanzada un recuento < 200 linfocitos CD4/μl en la primera determinación tras el diagnóstico, y como presentación tardía < 350 linfocitos CD4/μl. Se usaron la odds ratio y su intervalo de confianza del 95% como medida de asociación. Para el análisis multivariado de los factores asociados a enfermedad avanzada y presentación tardía se ajustó un modelo de regresión logística. Resultados Se incluyeron 13.021 nuevos diagnósticos, de los cuales el 87,7% tenía información de la variable de estudio. La mediana de CD4 fue de 363 (rango intercuartílico: 161-565). Durante el periodo, 3.356 pacientes (29,4%) cumplían la definición de enfermedad avanzada y 5.494 (48.1%) se clasificaron como presentación tardía. Tanto la enfermedad avanzada como la presentación tardía aumentaban con la edad, se asociaban al sexo masculino y a la transmisión a través del uso de drogas inyectadas o heterosexual. Ser inmigrante de cualquier origen, excepto de Europa Occidental, se asociaba a enfermedad avanzada y presentación tardía. Desagregando por sexo, el efecto de la edad y de la región de origen fue más débil en las mujeres que en los hombres. Conclusión A pesar de la cobertura universal en España, los hombres, los inmigrantes, los usuarios de drogas inyectadas y las personas infectadas por relaciones heterosexuales parecen tener más dificultad para acceder al seguimiento clínico (AU)

Predictors of advanced disease and late presentation in new HIV diagnoses reported to the surveillance system in Spain.

OBJECTIVE: To present surveillance data on advanced disease (AD) and late presentation (LP) of HIV in Spain and their determinants. METHODS: We included all new HIV diagnoses notified by the autonomous regions that consistently reported such cases throughout the period 2007-2011. Coverage was 54% of the total Spanish population. Data sources consisted of clinicians, laboratories and medical records. AD was defined as the presence of a CD4 cell count <200cells/µL in the first test after HIV diagnosis, while LP was defined as the presence of a CD4 cell count <350cells/µL after HIV diagnosis. Odds ratios and their 95% confidence intervals (OR, 95% CI) were used as the measure of association. Logistic regressions were fit to identify predictors of AD and LP. RESULTS: A total of 13,021 new HIV diagnoses were included. Among these, data on the outcome variable were available in 87.7%. The median CD4 count at presentation was 363 (interquartile range, 161-565). Overall, 3356 (29.4%) patients met the definition of AD and 5494 (48.1%) were classified as LP. Both AD and LP increased with age and were associated with male sex and infection through drug use or heterosexual contact. All immigrants except western Europeans were more prone to AD and LP. Multivariate models disaggregated by sex showed that the effect of age and region of origin was weaker in women than in men. CONCLUSIONS: Despite universal health care coverage in Spain, men, immigrants and people infected through drug use or heterosexual contact seem to be experiencing difficulties in gaining timely access to HIV care.

Influencia del lugar de origen en la utilización de pruebas de cribado de cáncer ginecológico en España / Impact of geographic origin on gynecological cancer screening in Spain

OBJETIVO: Analizar la asociación entre el área geográfica de procedencia en el uso de las citologías y la mamografía. MÉTODOS: Los datos analizados proceden Encuesta Nacional de Salud de España-2006 dirigida a población mayor de 16 años. La Encuesta incluye 13.422 mujeres. Las variables dependientes fueron realización de una mamografía y de una citología vaginal, ambos en los últimos 12 meses. La medida de asociación fue el odds ratio con intervalo de confianza al 95 por ciento calculado por regresión logística. RESULTADOS: Tomando como referencia la población española, la probabilidad de realizarse una mamografías entre las mujeres procedentes de África fue 0,36 (IC95 por ciento 0,21;0,62) veces menor; Europa del Este 0,40 (IC95 por ciento 0,22;0,74) veces menor; Europa Occidental, EEUU y Canadá, 0,60 (IC95 por ciento 0,43; 0,84) veces menor y América Central / Sur 0,64 (IC95 por ciento 0,52;0,81) veces menor. En relación a la prevención de cáncer de cervix, probabilidad de realizarse una citología entre las mujeres Europa del Este fue 0,38 (IC95 por ciento 0,28;0,50) veces menor que la población española, África 0,47 (IC95 por ciento:0,33;0,67) veces menor y Europa Occidental, EEUU y Canadá 0,61 (IC95 por ciento 0,46;0,81) veces menor. Dichas asociaciones fueron independientes de la edad, indicadores socioeconómicos, estado de salud y cobertura sanitaria. CONCLUSIONES: Las mujeres inmigrantes hacen menor uso de los programas de cribado que las mujeres autóctonas. Este dato podría reflejar dificultades de acceso a los programas preventivos.

OBJECTIVE: To assess the association between geographic origin and the use of screening cervical smears and mammograms. METHODS: Data was obtained from the 2006 Spanish National Health Survey that included 13,422 females over 16 years of age. The dependent variable was use of screening mammograms and cervical smears in the past 12 months. The measure of association (odds ratio and its related 95 percent confidence interval) was estimated using logistic regression. RESULTS: African women were 0.36 (95 percent CI 0.21,0.62), Eastern European 0.40 (95 percentCI 0.22;0.74), Western European, American and Canadian 0.60 (95 percentCI 0.43,0.84), and Central and South American 0.64 times (95 percentCI 0.52, 0.81) less likely to undergo a mammogram compared with the general population of Spain. In regard to cervical cancer screening, Eastern European women were 0.38 (95 percentCI 0.28,0.50), African 0.47 (95 percentCI 0.33,0.67) and Western European, American and Canadian 0.61 times (95 percentCI 0.46, 0.81) less likely to undergo cervical smears. These associations were independent of age, socioeconomic condition, health status and health insurance coverage. CONCLUSIONS: Immigrant women use less screening programs than native Spanish women. This finding may suggest difficult access to prevention programs.

Impact of geographic origin on gynecological cancer screening in Spain.

OBJECTIVE: To assess the association between geographic origin and the use of screening cervical smears and mammograms. METHODS: Data was obtained from the 2006 Spanish National Health Survey that included 13,422 females over 16 years of age. The dependent variable was use of screening mammograms and cervical smears in the past 12 months. The measure of association (odds ratio and its related 95% confidence interval) was estimated using logistic regression. RESULTS: African women were 0.36 (95% CI 0.21,0.62), Eastern European 0.40 (95%CI 0.22;0.74), Western European, American and Canadian 0.60 (95%CI 0.43,0.84), and Central and South American 0.64 times (95%CI 0.52, 0.81) less likely to undergo a mammogram compared with the general population of Spain. In regard to cervical cancer screening, Eastern European women were 0.38 (95%CI 0.28,0.50), African 0.47 (95%CI 0.33,0.67) and Western European, American and Canadian 0.61 times (95%CI 0.46, 0.81) less likely to undergo cervical smears. These associations were independent of age, socioeconomic condition, health status and health insurance coverage. CONCLUSIONS: Immigrant women use less screening programs than native Spanish women. This finding may suggest difficult access to prevention programs.

Pattern of health services use by immigrants from different regions of the world residing in Spain.

OBJECTIVE: To determine immigrants' frequency of use of four health services by place of origin and compare it with that of the Spanish population. METHODS: Based on the 2006 National Health Survey in Spain, we estimated the frequency of use of four health services in men and women from: Spain, Western countries, Eastern Europe, Latin America, North Africa, Sub Saharan Africa and Asia/Oceania. These results were compared with the Spanish population by calculating odds ratios adjusted for age, socioeconomic position, health status, and type of health coverage. RESULTS: Immigrant men generally use health services less frequently than Spanish nationals. The main exceptions are Latin American men, who more often use emergency services (OR 1.68, 95% CI 1.41-1.99) and Sub-Saharan men, who use specialists more frequently (OR 2.93, 1.70-5.05). Immigrant women use health services about as frequently as Spanish women. The main exceptions are North African women, who less frequently use specialists (OR 0.39, 0.22-0.71) and Sub-Saharan women who more frequently use GPs (OR 4.06, 2.21-7.44), specialists (OR 2.29, 1.06-4.95) and emergency services (OR 2.92, 1.49-5.72). CONCLUSIONS: Health services use by the immigrant population in Spain differs by gender and place of origin.

Retraso diagnóstico de la infección por el virus de la inmunodeficiencia humana en España / Delayed diagnosis of HIV infection in Spain

Objetivos Analizar el porcentaje de retraso diagnóstico (RD) de la infección por el virus de la inmunodeficiencia humana (VIH), su tendencia y factores asociados a partir de los datos procedentes del Sistema de Información de Nuevos Diagnósticos de VIH (SINIVIH) en España.Métodos Estudio descriptivo sobre las personas diagnosticadas de VIH durante 2003–2007 en las 8 comunidades autónomas (CCAA) actualmente participantes. Se definió como RD la presencia de <200CD4/μl al diagnóstico. Mediante regresión logística se obtuvieron las odds ratio (OR) y su intervalo de confianza al 95% (IC95%).Resultados Se notificaron 5.785 nuevos diagnósticos de VIH, de los que 4.798 disponían de cifra de CD4 al diagnóstico. De estos, el 37,3% cumplieron la definición de retraso. Un 19% adicional tenía entre 200–350 CD4. El porcentaje de RD era menor en mujeres que en hombres (32,9% frente a 38,6%), y mayor en heterosexuales (42,4%) y usuarios de drogas inyectadas (UDI) (40,1%) que en los hombres que mantienen relaciones sexuales con hombres (HSH) (26,7%). Ajustando por CCAA y año de diagnóstico la probabilidad de RD en españoles es mayor en hombre (OR=1,49; IC95%:1,21–1,85); en: 30–39 años (OR=2,08; IC95%:1,63–2,67), 40–49 años (OR=3,98; IC95%:3,07–5,16) y >49 años (OR=6,77; IC95%:5,10–9,00) frente a 20–29 años; y en heterosexuales (OR=1,75; IC95%:1,43–2,15) y UDI (OR=1,75; IC95%:1,38–2,22) comparados con los HSH. El RD disminuyó de 2003 a (..) (AU)

Objectives To analyse the prevalence of delayed diagnosis (DD) of human immunodeficiency virus (HIV) infection, the trends over time and its determining factors from the Newly Diagnosed HIV-infected individuals Information System (SINIVIH) data, in process of being implemented in Spain.Methods Cross-sectional study of newly diagnosed HIV-infected individuals between 2003 and 2007 in the 8 currently participating Spanish autonomous regions (AR). DD was defined as a CD4 count <200cells/μL at diagnosis. Adjusted odds ratios with 95% confidence interval were calculated using logistic regression (OR; 95%CI).Results Among the 5785 newly diagnosed HIV cases reported, 4798 had a CD4 cell count at diagnosis. Of these, 37.3% met the DD definition. An additional 19% had between 200 and 350cells/μL. The proportion of DD was lower for women than for men (32.9% versus 38.6%). According to exposure category, it was higher in heterosexuals (42.4%) and injecting drug users (IDUs) (40.1%) than in men who have sex with men (MSM) (26.7%). In the Spanish patient group, in multivariate logistic regression analyses, adjusting for AR and year of diagnosis, men were more likely to have a DD (OR=1.49; 95%CI:1.21–1.85). Compared to younger patients (20–29 years), LD was more frequent in older: 30–39 years (OR=2.08; 95% CI:1.63–2.67), 40–49 years (OR=3.98; 95% CI:3.07–5.16) and >49 years (OR=6.77; 95% CI:5.10–9.00); and compared to MSM, was more frequent in heterosexuals (OR=1.75; 95% CI:1.43–2.15) and IDUs (OR=1.75; 95% CI:1.38–2.22). DD decreased from 2003 to 2007 (OR=1.38; 95% CI:1.08–1.76). The same associated factors were found in immigrants, but with different magnitude: stronger association with men, heterosexuals and IDUs, and weaker association with older age. (..) (AU)

[Delayed diagnosis of HIV infection in Spain]. / Retraso diagnóstico de la infección por el virus de la inmunodeficiencia humana en España.

OBJECTIVES: To analyse the prevalence of delayed diagnosis (DD) of human immunodeficiency virus (HIV) infection, the trends over time and its determining factors from the Newly Diagnosed HIV-infected individuals Information System (SINIVIH) data, in process of being implemented in Spain. METHODS: Cross-sectional study of newly diagnosed HIV-infected individuals between 2003 and 2007 in the 8 currently participating Spanish autonomous regions (AR). DD was defined as a CD4 count <200cells/µL at diagnosis. Adjusted odds ratios with 95% confidence interval were calculated using logistic regression (OR; 95%CI). RESULTS: Among the 5785 newly diagnosed HIV cases reported, 4798 had a CD4 cell count at diagnosis. Of these, 37.3% met the DD definition. An additional 19% had between 200 and 350cells/µL. The proportion of DD was lower for women than for men (32.9% versus 38.6%). According to exposure category, it was higher in heterosexuals (42.4%) and injecting drug users (IDUs) (40.1%) than in men who have sex with men (MSM) (26.7%). In the Spanish patient group, in multivariate logistic regression analyses, adjusting for AR and year of diagnosis, men were more likely to have a DD (OR=1.49; 95%CI:1.21-1.85). Compared to younger patients (20-29 years), LD was more frequent in older: 30-39 years (OR=2.08; 95% CI:1.63-2.67), 40-49 years (OR=3.98; 95% CI:3.07-5.16) and >49 years (OR=6.77; 95% CI:5.10-9.00); and compared to MSM, was more frequent in heterosexuals (OR=1.75; 95% CI:1.43-2.15) and IDUs (OR=1.75; 95% CI:1.38-2.22). DD decreased from 2003 to 2007 (OR=1.38; 95% CI:1.08-1.76). The same associated factors were found in immigrants, but with different magnitude: stronger association with men, heterosexuals and IDUs, and weaker association with older age. CONCLUSIONS: DD affects almost four in every ten newly diagnosed HIV-infected individuals, and is significantly more common among men, age group over 30 years, IDUs and heterosexuals. These are associated factors both in Spanish and immigrants, but in the last group the association is stronger. Strategies to increase the perception of risk among these groups are needed, as well as the implementation of the SINIVIH in the whole country to improve and to extend the information on DD.

[Respiratory work and pattern with different proportional assist ventilation levels]. / Trabajo y patrón respiratorio con diferentes niveles de ventilación asistida proporcional.

OBJECTIVE: To study the minimum assistance level during proportional assist ventilation (PAV) to decrease the work of breathing to physiological limits (0.6 j/l) and the relationship between breathing pattern changes and respiratory effort at different PAV levels. DESIGN: Prospective cohort study. SETTING: Polyvalent intensive care unit of a teaching hospital of Jaen, Spain. PATIENTS AND METHODS: Twelve long-term mechanical ventilated patients who met criteria to initiate weaning from the ventilator. INTERVENTIONS: We used the Puritan-Bennett 840 ventilator in proportional assist ventilation. The percentage of support was randomly modified between 5% and 80%, in intervals of 10%. Prior to the change in the PAV level, the patients were ventilated in assist-volume control followed by pressure support ventilation. MAIN VARIABLES OF INTEREST: Before PAV, we measured the respiratory mechanics and the breathing pattern and work of breathing during this mode. RESULTS: The decrease in respiratory assist in PAV was related to significantly higher work of breathing, this going from 0.2+/-0,07 (0.1-0.3) j/l with PAV80 to 0.9+/-0.2 (0.4-1.5) j/l with PAV5 (p=0.002). The coefficient correlation between PAV level and work of breathing (measured as j/l and j/min) was r=-0.8 and -0.6, respectively. Minimum PAV level related with physiological work of breathing was 30% (0.63+/-0.13 j/l). Except for the tidal volume that increased significantly (PAV80 vs PAV5=0.4+/-0.1 vs 0.3+/-0.1; p=0.02), the remaining variables defining the breathing pattern did not changed with the increase in PAV. CONCLUSIONS: In the group of patients studied, the increase in the PAV levels decreases work of breathing, without significantly changing the breathing pattern. Levels lower than 30% of PAV are associated to excessive work of breathing.

Trabajo y patrón respiratorio con diferentes niveles de ventilación asistida proporcional / Respiratory work and pattern with different proportional assist ventilation levels

Objetivo: Estudiar el grado mínimo de asistencia, en ventilación proporcional asistida (VPA), que disminuya el trabajo respiratorio a límites fisiológicos (0,6 j/l), y la relación entre los cambios en el patrón respiratorio y el esfuerzo que realiza el paciente a diferentes niveles de VPA. Diseño: estudio de cohortes prospectivo. Ámbito: Unidad de Medicina Intensiva polivalente del Complejo Hospitalario de Jaén. Pacientes y métodos: Se incluye a 12 pacientes que han precisado ventilación mecánica prolongada, y cumplen criterios para iniciar la retirada del respirador. Intervenciones: utilizamos el respirador Puritan-Bennett 840 en modo proporcional asistido. De forma aleatoria se modifica el porcentaje de asistencia entre el 5 y el 80%, en intervalos del 10%. Antes de cada modificación del nivel de VPA, el paciente recibe ventilación asistida controlada por volumen seguida de presión soporte. Principales variables de interés: medimos la mecánica respiratoria antes del inicio de VPA y, en este modo de ventilación asistida, el patrón respiratorio y el trabajo respiratorio. Resultados: El descenso en la asistencia respiratoria con VPA conlleva un aumento significativo del trabajo respiratorio, que va desde 0,2 ± 0,07 (0,1-0,3) j/l con VPA80 hasta 0,9 ± 0,2 (0,4-1,5) j/l con VPA5 (p = 0,002). El coeficiente de correlación entre el nivel de VPA y el trabajo respiratorio (medido en j/l y j/min) fue r = -0,8 y -0,6, respectivamente. El grado mínimo de asistencia en relación con un trabajo fisiológico fue del 30% (0,63 ± 0,13 j/l). Excepto el volumen corriente que aumentó de forma significativa (VPA80 de 0,4 ± 0,1; VPA5 de 0,3 ± 0,1; p = 0,02), los demás parámetros que definen el patrón respiratorio no cambiaron con el aumento de VPA. Conclusiones: En el grupo de pacientes estudiado, al aumentar la asistencia respiratoria con VPA disminuye el trabajo respiratorio, sin cambiar el patrón respiratorio de forma significativa. Valores menores del 30% de VPA conllevan un excesivo trabajo respiratorio (AU)

Objective: To study the minimum assistance level during proportional assist ventilation (PAV) to decrease the work of breathing to physiological limits (0.6 j/l) and the relationship between breathing pattern changes and respiratory effort at different PAV levels. Design: Prospective cohort study. Setting: Polyvalent intensive care unit of a teaching hospital of Jaen, Spain. Patients and methods: Twelve long-term mechanical ventilated patients who met criteria to initiate weaning from the ventilator. Interventions: We used the Puritan-Bennett 840 ventilator in proportional assist ventilation. The percentage of support was randomly modified between 5% and 80%, in intervals of 10%. Prior to the change in the PAV level, the patients were ventilated in assist-volume control followed by pressure support ventilation. Main variables of interest: Before PAV, we measured the respiratory mechanics and the breathing pattern and work of breathing during this mode. Results: The decrease in respiratory assist in PAV was related to significantly higher work of breathing, this going from 0.2 ± 0,07 (0.1-0.3) j/l with PAV80 to 0.9 ± 0.2 (0.4-1.5) j/l with PAV5 (p = 0.002). The coefficient correlation between PAV level and work of breathing (measured as j/l and j/min) was r = -0.8 and -0.6, respectively. Minimum PAV level related with physiological work of breathing was 30% (0.63 ± 0.13 j/l). Except for the tidal volume that increased significantly (PAV80 vs PAV5 = 0.4 ± 0.1 vs 0.3 ± 0.1; p = 0.02), the remaining variables defining the breathing pattern did not changed with the increase in PAV. Conclusions: In the group of patients studied, the increase in the PAV levels decreases work of breathing, without significantly changing the breathing pattern. Levels lower than 30% of PAV are associated to excessive work of breathing (AU)