Effects of High-Flow Nasal Cannula on End-Expiratory Lung Impedance in Semi-Seated Healthy Subjects.

BACKGROUND: High-flow nasal cannula (HFNC) enables delivery of humidified gas at high flow while controlling the FIO2 . Although its use is growing in patients with acute respiratory failure, little is known about the impact of HFNC on lung volume. Therefore, we aimed to assess lung volume changes in healthy subjects at different flows and positions. METHODS: This was a prospective physiological study performed in 16 healthy subjects. The changes in lung volumes were assessed by measuring end-expiratory lung impedance by using electrical impedance tomography. All the subjects successively breathed during 5 min in these following conditions: while in a supine position without HFNC (T0) and 3 measurements in a semi-seated position at 45° without HFNC (T1), and with HFNC at a flow of 30 L/min (T2), and 50 L/min (T3). RESULTS: Compared with the supine position, the values of end-expiratory lung impedance significantly increased with the subjects in a semi-seated position. End-expiratory lung impedance significantly increased after HFNC initiation in subjects in a semi-seated position and further increased by increasing flow at 50 L/min. When taking the end-expiratory lung impedance measurement in subjects in a semi-seated position (T1) as reference, the differences among the medians of global end-expiratory lung impedance were statistically significant (P < .001), which amounted to 1.05 units in T1; 1.12 units in T2; and 1.44 units in T3 (P < .05 for all comparisons, Wilcoxon test). The breathing frequency did not differ between the supine and semi-seated position (T0 and T1) but significantly decreased after initiation of HFNC and further decreased at high flow. T0 and T1 were not different (P = .13); whereas there was a statistically significant difference among T1, T2, and T3 (P < .05, post hoc test with Bonferroni correction). CONCLUSIONS: In healthy subjects, the semi-seated position and the use of HFNC increased end-expiratory lung impedance globally. These changes were accompanied by a significant decrease in the breathing frequency.

Ventilación mecánica en pacientes con falla respiratoria aguda hipoxémica / Mechanical ventilation in patients with acute hypoxemic respiratory failure

Objetivo: Describir las características clínicas de los pacientes internados en la UCI con requerimiento de VMi con FRAH-No SDRA. Evaluar la asociación de la mortalidad con diferentes variables. Diseño: Cohorte de comienzo. Ámbito: Estudio realizado en 2 UCIs argentinas del ámbito privado de la salud, entre el 01/07/2013 y 31/12/2014. Pacientes: De una muestra consecutiva de 2526 pacientes, se incluyeron a 229 mayores de 18 años, que ingresaron a la UCI con requirimiento de VMi por más de 24hs desarrollando FRAH-No SDRA. Variables de interés principales: Se registraron variables demográficas, estadía en VMi y en UCI, variables de programación inicial del respirador, variables de monitoreo y evolución al alta. También se registraron el número y tipo de complicaciones desarrolladas durante el periodo de VMi Resultados: El 70,7% de los ingresos fue por causa médica. El SAPS II fue de 42. El tiempo de VMi y de estadía en UCI fue mayor en los pacientes con delirio (p < 0,0001 en ambos). En el modelo de regresión logística ajustado por severidad de la hipoxemia, la edad (OR 1,02; IC95% 1,002-1,04: p = 0,033) y el shock (OR 2,37; IC95% 1,12-5: p = 0,023) resultaron predictores independientes de mortalidad. Conclusiones: En este grupo de pacientes que requirieron VMi por más de 24 hs y desarrollaron FRAH-No SDRA se encontró una distribución demográfica similar a la descripta por otros reportes. La mortalidad no se relacionó con la severidad de la hipoxemia, mientras que el shock y la edad fueron predictores independientes de mortalidad.

Mechanical ventilation in patients with acute hypoxemic respiratory failure

Objective: To describe the clinical characteristics of patients with AHRF (without ARDS) hospitalized in the ICU who require IMV. To evaluate the association between mortality and different variables. Design: Inception cohort. Scope: This study was conducted in two Argentine ICUs from the private health sector between 07/01/2013 and 12/31/2014. Patients: From a consecutive sample of 2526 patients, 229 individuals aged 18 and upwards were included in the study; they were admitted to the ICU requiring IMV for over 24 hours and developed AHRF (without ARDS). Primary endpoints: Demographic variables and variables associated with the number of days with IMV and at the ICU were documented, as well as the initial setting of the respirator, monitoring variables and evolution at discharge. Likewise, the number and type of complications developed during the period of IMV were documented. Results: 70.7% of admissions were for medical reasons. SAPS II score was 42. The period of IMV and at the ICU was higher in patients with delirium (p<0.0001 in both). In the logistic regression model adjusted by the severity of hypoxemia, age (OR 1.02; 95% CI 1.002-1.04: p = 0.033) and shock (OR 2.37; 95% CI 1.12-5: p = 0.023) acted as independent predictors of mortality. Conclusions: In this group of patients who required IMV for over 24 hours and who developed AHRF (without ARDS) there was a demographic distribution similar to that described in other reports. Mortality was not associated with the severity of hypoxemia, whereas shock and age were independent predictors of mortality.

Calidad de vida y estatus funcional en pacientes que requirieron ventilación mecánica: Seguimiento al año del alta de terapia intensiva / Quality of Life and Functional Status in Patients with Mechanical Ventilation. One Year Follow-up After Discharge from ICU

Objetivo: Evaluar el estatus funcional (EF) y calidad de vida (CV) posterior al alta de terapia intensiva (UTI) en pacientes con ventilación mecánica invasiva (VM) y compararla con la población de referencia. Diseño: Cohorte prospectivo. Ámbito: UTI Sanatorio Anchorena, Buenos Aires, Argentina. Pacientes: Aquellos ingresados a UTI entre septiembre 2008 y abril 2009 con más de 24 hs de VM. Intervenciones: A los 4 meses y al año se evaluó telefónicamente la CVa través del cuestionario EQ-5D y el EF con el índice de Barthel que evalúa actividades de la vida diaria (AVD). Resultados: 77 pacientes recibieron VM, 41 mujeres (53%), mediana de edad 65 años [IC25-75% 55-77)], SAPSII 41 [28-52], días de VM 4 [2-8]. 47 pacientes sobrevivieron a la internación y fueron evaluados, 40 (85.1%) a los 4 meses y 34 (72.3%) al año. El EQ-5D a los 4 meses (mediana 0.693 IC25-75% 0.182-0.982) y al año (mediana 0.841 IC25-75% 0.493-1), se diferenciaron significativamente de la población argentina (p = 0.0004 y 0.024 respectivamente). A los 4 meses, la mitad de los pacientes presentaban dificultades en todos los dominios del EQ-5D y el 57% eran dependientes en las AVD. Al año, el 54% de los pacientes no había regresado a sus actividades previas y padecían ansiedad/depresión mientras que el 45% aún eran dependientes en las AVD. Conclusiones: Las consecuencias de la internación en UTI por una enfermedad aguda están presentes a los 4 meses y al año del alta, determinando una población con una CV significativamente menor a la no expuesta y un EF deteriorado.

Objective: To study functional status (FS) and quality of life (QoL) after discharge from intensive care unit (ICU) in patients who had > 24 hours of mechanical ventilation (MV) and to compare them with reference Argentine population. Design: Prospective cohort study. Setting: ICU at Sanatorio Anchorena, Buenos Aires , Argentina. Patients: All patients admitted to the ICU between September 2008 and April 2009 with more than 24 hours of MV. Procedures: QoL was assessed by EQ-5D and FS was evaluated through Barthel index [evaluation of daily life activities (DLA)] by telephone at 4 months and 1 year after discharge from ICU. Results: 77 patients required MV, 41 females (53%), median age 65 years (IQR 55-77), SAPSII 41 (28-52), days of MV 4 (2-8). 47 patients survived after hospitalization, 40 (85.1%) at 4 months and 34 (72.3%) one year later. The EQ-5D at 4 months (median 0.693 IQR0.182-0.982) and at 1 year (median 0.841 IQR0.493-1) of follow up were significantly lower compared with general Argentine population (p = 0.0004 and 0.024 respectively). At 4 months, half of the patients had problems in all dimensions of the Euroqol and 57% were dependent on DLA. At 1 year, 54% could not return to their previous activities, suffered from anxiety/depression and 45% were dependent on DLA. Conclusions: Effects of critical illness and ICU stay are present at 4 months and 1 year after discharge. Survivors suffer a lower quality of life and functional status than general population.