Effects on Humidification and Ventilatory Parameters of Three Single-limb Heated-wired Circuits for Non-invasive Ventilation: A Bench Study / Efectos sobre la humidificación y los parámetros de ventilación de 3 circuitos de ramal único con cable calefactado para la ventilación mecánica no invasiva: estudio experimental

Background: The objective of this study was to evaluate the effects of three single-limb heated wired circuits (SLHWC) for NIV, on ventilatory parameters and humidification performance in a simulation lung model. Methods: Three SLHWC compatible with the MR-850 Heated Humidifier (HH) (Fisher & Paykel, Auckland, New Zealand) were tested: RT-319 (FP) (Fisher & Paykel, Auckland, New Zealand), Respironics 1045770 (RP) (DEAS, Castel Bolognese, Italy) and Intersurgical B/SYS 5809001 (IT) (Intersurgical, Wokingham, UK). A Bipap Vision ventilator (Philips Respironics, Murrysville, PA, USA) in pressure control ventilation (PCV) connected to a test lung was used for simulation. Each SHWC performance was evaluated in four ventilatory conditions: IPAP of 15 cm H2O with FiO2 0.3 and 1, respectively; and, IPAP of 25 cm H2O with FiO2 0.3 and 1, respectively. EPAP was set at 5 cm H2O. Hygrometric and ventilatory measurements including: relative humidity (RH), temperature (T), Pplat, PIP, PEEP, peak inspiratory flow (PIF), and tidal volume (Vt) were measured. Results: In each FiO2 group absolute humidity (AH) was similar with FP regardless of the IPAP level employed compared to IT and RP (P<.001). Except for RP at FiO2 0.3, AH increased significantly in IT and RP groups as IPAP increased (P < .001). PIP, Pplat, PEEP, PIF, and Vt values were significantly higher with FP and RP in each FiO2 group compared to IT (P < .001). Conclusions: Humidification performance varied significantly among the three circuits, being FP the only one able to maintain stable AH values during the study with no influence on ventilatory parameters

Introducción: El objetivo de este estudio fue evaluar los efectos de 3 circuitos de ramal único (SLHWC) para la ventilación mecánica no invasiva (VNI) en los parámetros de ventilación y la humidificación en un modelo de simulación pulmonar. Métodos: Se evaluaron 3 SLHWC compatibles con el humidificador calefactado MR-850 (HH) (Fisher & Paykel, Auckland, Nueva Zelanda): RT-319 (FP) (Fisher & Paykel, Auckland, Nueva Zelanda), Respironics 1045770 (RP) (DEAS, Castel Bolognese, Italia) y Intersurgical B/SYS 5809001 (IT) (Intersurgical, Wokingham, Reino Unido). Para la simulación se empleó un ventilador Bipap Vision (Philips Respironics, Murrysville, PA, EE. UU.) con ventilación controlada por presión (PCV) conectado a un simulador pulmonar. El rendimiento de cada SHWC se evaluó en 4 condiciones ventilatorias: IPAP de 15 cm H2O con FiO2 igual a 0,3 o igual a 1; IPAP de 25 cm H2O con FiO2 igual a 0,3 o igual a 1. La EPAP se estableció en 5 cm H2O. Las medidas ventilatorias e higrométricas incluyeron: humedad relativa (HR) humedad absoluta (AH), temperature (T), Pplat, PIP, PEEP, pico de flujo inspiratorio (PIF) y volumen tidal (Vt). Resultados: Para cada grupo de FiO2 FP detectó valores similares de humedad absoluta (HA) en comparación con IT y RP (p<0,001), independientemente del nivel IPAP utilizado. Se registró un incremento significativo de la HA en todos los grupos medidos con IT y RP conforme aumentaron los valores de IPAP (p<0,001), excepto en el grupo de FiO2, igual a 0,3 medido con RP. Los valores de PIP, Pplat, PEEP, PIF y Vt resultaron significativamente más elevados con FP y RP en cada grupo FiO2 en comparación con IT (p < 0 ,001). Conclusiones: La evaluación de la humidificación varió significativamente entre los 3 circuitos, siendo FP el único capaz de mantener estables los valores de HA durante el estudio sin influencia alguna de los parámetros ventilatorios

Effects on Humidification and Ventilatory Parameters of Three Single-limb Heated-wired Circuits for Non-invasive Ventilation: A Bench Study.

BACKGROUND: The objective of this study was to evaluate the effects of three single-limb heated wired circuits (SLHWC) for NIV, on ventilatory parameters and humidification performance in a simulation lung model. METHODS: Three SLHWC compatible with the MR-850 Heated Humidifier (HH) (Fisher & Paykel, Auckland, New Zealand) were tested: RT-319 (FP) (Fisher & Paykel, Auckland, New Zealand), Respironics 1045770 (RP) (DEAS, Castel Bolognese, Italy) and Intersurgical B/SYS 5809001 (IT) (Intersurgical, Wokingham, UK). A Bipap Vision ventilator (Philips Respironics, Murrysville, PA, USA) in pressure control ventilation (PCV) connected to a test lung was used for simulation. Each SHWC performance was evaluated in four ventilatory conditions: IPAP of 15cmH2O with FiO2 0.3 and 1, respectively; and, IPAP of 25cmH2O with FiO2 0.3 and 1, respectively. EPAP was set at 5cmH2O. Hygrometric and ventilatory measurements including: relative humidity (RH), temperature (T), Pplat, PIP, PEEP, peak inspiratory flow (PIF), and tidal volume (Vt) were measured. RESULTS: In each FiO2 group absolute humidity (AH) was similar with FP regardless of the IPAP level employed compared to IT and RP (P<.001). Except for RP at FiO2 0.3, AH increased significantly in IT and RP groups as IPAP increased (P<.001). PIP, Pplat, PEEP, PIF, and Vt values were significantly higher with FP and RP in each FiO2 group compared to IT (P<.001). CONCLUSIONS: Humidification performance varied significantly among the three circuits, being FP the only one able to maintain stable AH values during the study with no influence on ventilatory parameters.

Measuring cardiac output in children undergoing cardiac catheterization: comparison between the Fick method and PRAM (pressure recording analytical method).

BACKGROUND: Pressure recording analytical method (PRAM) is a novel, arterial pulse contour method for measuring cardiac output (CO). Validation studies of PRAM in children are few, and have shown contradictory results. The aim of the study was to compare the MostCare® -PRAM vs the Fick method of cardiac output estimation (reference method). METHODS: This is a single-center, prospective observational study in 52 pediatric patients who underwent diagnostic right and left heart catheterization. Cardiac index (CI) measurements with the MostCare® -PRAM vs the Fick method were obtained under hemodynamically stable conditions. RESULTS: Forty CI measurements were performed. The data showed good agreement between CIFick and CIPRAM : r2 = 0.90 (P < 0.001), mean bias -0.075, limits of agreement from -0.56 to 0.41. The percentage error was 17%. Comparable results were obtained for patients <20 kg (r2 = 0.87, P < 0.001), mean bias -0.135, limits of agreement from -0.35 to 0.62, percentage of error 17%. CONCLUSIONS: In pediatric patients undergoing diagnostic right and left heart catheterization, the MostCare® -PRAM was shown to estimate CI with a good level of agreement with the Fick method measurements.

Comparison Between Doppler-Echocardiography and Uncalibrated Pulse Contour Method for Cardiac Output Measurement: A Multicenter Observational Study.

OBJECTIVES: Echocardiography and pulse contour methods allow, respectively, noninvasive and less invasive cardiac output estimation. The aim of the present study was to compare Doppler echocardiography with the pulse contour method MostCare for cardiac output estimation in a large and nonselected critically ill population. DESIGN: A prospective multicenter observational comparison study. SETTING: The study was conducted in 15 European medicosurgical ICUs. PATIENTS: We assessed cardiac output in 400 patients in whom an echocardiographic evaluation was performed as a routine need or for cardiocirculatory assessment. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: One echocardiographic cardiac output measurement was compared with the corresponding MostCare cardiac output value per patient, considering different ICU admission categories and clinical conditions. For statistical analysis, we used Bland-Altman and linear regression analyses. To assess heterogeneity in results of individual centers, Cochran Q, and the I statistics were applied. A total of 400 paired echocardiographic cardiac output and MostCare cardiac output measures were compared. MostCare cardiac output values ranged from 1.95 to 9.90 L/min, and echocardiographic cardiac output ranged from 1.82 to 9.75 L/min. A significant correlation was found between echocardiographic cardiac output and MostCare cardiac output (r = 0.85; p < 0.0001). Among the different ICUs, the mean bias between echocardiographic cardiac output and MostCare cardiac output ranged from -0.40 to 0.45 L/min, and the percentage error ranged from 13.2% to 47.2%. Overall, the mean bias was -0.03 L/min, with 95% limits of agreement of -1.54 to 1.47 L/min and a relative percentage error of 30.1%. The percentage error was 24% in the sepsis category, 26% in the trauma category, 30% in the surgical category, and 33% in the medical admission category. The final overall percentage error was 27.3% with a 95% CI of 22.2-32.4%. CONCLUSIONS: Our results suggest that MostCare could be an alternative to echocardiography to assess cardiac output in ICU patients with a large spectrum of clinical conditions.

Active humidification with Boussignac CPAP: in vitro study of a new method.

OBJECTIVE: To carry out an in vitro study of Boussignac CPAP valve performance with a new humidification method, using a heated humidifier. METHODS: Two heated humidifiers were evaluated: Fisher & Paykel MR850, and Covidien Kendall Aerodyne 2000. Baseline measurements were taken in all experimental conditions without humidification. The Boussignac valve was adapted to the input of the humidification chamber. The system was connected to a test lung to assess the degree of pressurization. Hygrometric and pressure measurements were performed with the following gas flows: 10, 20, 30 and 40 L/min. RESULTS: The mean values of pressure generated by the Boussignac valve were 1.99 ± 0.02, 6.97 ± 0.05, 16.61 ± 0.08 and 21.24 ± 0.08 cm H2O, 10, 20, 30 and 40 L/min, respectively, no differences being detected between study groups. Overall absolute humidity was significantly greater with a heated humidifier than without humidification (range 40.01 ± 0.57-25.46 ± 0.49 compared to 0.16 ± 0.13 mgH2O/L, P < .001). Absolute humidity was significantly higher in Kendall Aerodyne 2000 compared to MR850, regardless of the selected temperature and flow (P < .001). CONCLUSIONS: This new method of Boussignac CPAP humidification yielded humidity values above 25 mg H2O/L regardless of the heated humidifier and flow used. Pressurization values remained constant in each experimental situation and were not influenced by adding humidification. These data open up the possibility of using Boussignac CPAP on different types of patients, with different interfaces and for long periods of time.