Comparative bench study evaluation of different infant interfaces for non-invasive ventilation.

BACKGROUND: To compare, in terms of patient-ventilator interaction and performance, a new nasal mask (Respireo, AirLiquide, FR) with the Endotracheal tube (ET) and a commonly used nasal mask (FPM, Fisher and Paykel, NZ) for delivering Pressure Support Ventilation (PSV) in an infant model of Acute Respiratory Failure (ARF). METHODS: An active test lung (ASL 5000) connected to an infant mannequin through 3 different interfaces (Respireo, ET and FPM), was ventilated with a standard ICU ventilator set in PSV. The test lung was set to simulate a 5.5 kg infant with ARF, breathing at 50 and 60 breaths/min). Non-invasive ventilation (NIV) mode was not used and the leaks were nearly zero. RESULTS: The ET showed the shortest inspiratory trigger delay and pressurization time compared to FPM and Respireo (p < 0.01). At each respiratory rate tested, the FPM showed the shortest Expiratory trigger delay compared to ET and Respireo (p < 0.01). The Respireo presented a lower value of Inspiratory pressure-time product and trigger pressure drop than ET (p < 0.01), while no significant difference was found in terms of pressure-time product at 300 and 500 ms. During all tests, compared with the FPM, ET showed a significantly higher tidal volume (VT) delivered (p < 0.01), while Respireo showed a trend toward an increase of tidal volume delivered compared with FPM. CONCLUSIONS: The ET showed a better patient-ventilator interaction and performance compared to both the nasal masks. Despite the higher internal volume, Respireo showed a trend toward an increase of the delivered tidal volume; globally, its efficiency in terms of patient-ventilator interaction was comparable to the FPM, which is the infant NIV mask characterized by the smaller internal volume among the (few) models on the market.

Switches in non-invasive respiratory support strategies during acute hypoxemic respiratory failure: Need to monitoring from a retrospective observational study.

OBJECTIVE: To explore combined non-invasive-respiratory-support (NIRS) patterns, reasons for NIRS switching, and their potential impact on clinical outcomes in acute-hypoxemic-respiratory-failure (AHRF) patients. DESIGN: Retrospective, single-center observational study. SETTING: Intensive Care Medicine. PATIENTS: AHRF patients (cardiac origin and respiratory acidosis excluded) underwent combined NIRS therapies such as non-invasive-ventilation (NIV) and High-Flow-Nasal-Cannula (HFNC). INTERVENTIONS: Patients were classified based on the first NIRS switch performed (HFNC-to-NIV or NIV-to-HFNC), and further specific NIRS switching strategies (NIV trial-like vs. Non-NIV trial-like and single vs. multiples switches) were independently evaluated. MAIN VARIABLES OF INTEREST: Reasons for switching, NIRS failure and mortality rates. RESULTS: A total of 63 patients with AHRF were included, receiving combined NIRS, 58.7% classified in the HFNC-to-NIV group and 41.3% in the NIV-to-HFNC group. Reason for switching from HFNC to NIV was AHRF worsening (100%), while from NIV to HFNC was respiratory improvement (76.9%). NIRS failure rates were higher in the HFNC-to-NIV than in NIV-to-HFNC group (81% vs. 35%, p < 0.001). Among HFNC-to-NIV patients, there was no difference in the failure rate between the NIV trial-like and non-NIV trial-like groups (86% vs. 78%, p = 0.575) but the mortality rate was significantly lower in NIV trial-like group (14% vs. 52%, p = 0.02). Among NIV to HFNC patients, NIV failure was lower in the single switch group compared to the multiple switches group (15% vs. 53%, p = 0.039), with a shorter length of stay (5 [2-8] vs. 12 [8-30] days, p = 0.001). CONCLUSIONS: NIRS combination is used in real life and both switches' strategies, HFNC to NIV and NIV to HFNC, are common in AHRF management. Transitioning from HFNC to NIV is suggested as a therapeutic escalation and in this context performance of a NIV-trial could be beneficial. Conversely, switching from NIV to HFNC is suggested as a de-escalation strategy that is deemed safe if there is no NIRS failure.

Lung volumes and lung volume recruitment in ARDS: a comparison between supine and prone position.

BACKGROUND: The use of positive end-expiratory pressure (PEEP) and prone position (PP) is common in the management of severe acute respiratory distress syndrome patients (ARDS). We conducted this study to analyze the variation in lung volumes and PEEP-induced lung volume recruitment with the change from supine position (SP) to PP in ARDS patients. METHODS: The investigation was conducted in a multidisciplinary intensive care unit. Patients who met the clinical criteria of the Berlin definition for ARDS were included. The responsible physician set basal PEEP. To avoid hypoxemia, FiO2 was increased to 0.8 1 h before starting the protocol. End-expiratory lung volume (EELV) and functional residual capacity (FRC) were measured using the nitrogen washout/washin technique. After the procedures in SP, the patients were turned to PP and 1 h later the same procedures were made in PP. RESULTS: Twenty-three patients were included in the study, and twenty were analyzed. The change from SP to PP significantly increased FRC (from 965 ± 397 to 1140 ± 490 ml, p = 0.008) and EELV (from 1566 ± 476 to 1832 ± 719 ml, p = 0.008), but PEEP-induced lung volume recruitment did not significantly change (269 ± 186 ml in SP to 324 ± 188 ml in PP, p = 0.263). Dynamic strain at PEEP decreased with the change from SP to PP (0.38 ± 0.14 to 0.33 ± 0.13, p = 0.040). CONCLUSIONS: As compared to supine, prone position increases resting lung volumes and decreases dynamic lung strain.

Remifentanil effects on respiratory drive and timing during pressure support ventilation and neurally adjusted ventilatory assist.

We assessed the effects of varying doses of remifentanil on respiratory drive and timing in patients receiving Pressure Support Ventilation (PSV) and Neurally Adjusted Ventilatory Assist (NAVA). Four incrementing remifentanil doses were randomly administered to thirteen intubated patients (0.03, 0.05, 0.08, and 0.1µg·Kg-1·min-1) during both PSV and NAVA. We measured the patient's (Ti/Ttotneu) and ventilator (Ti/Ttotmec) duty cycle, the Electrical Activity of the Diaphragm (EAdi), the inspiratory (Delaytrinsp) and expiratory (Delaytrexp) trigger delays and the Asynchrony Index (AI). Increasing doses of remifentanil did not modify EAdi, regardless the ventilatory mode. In comparison to baseline, remifentanil infusion >0.05µg/Kg-1/min-1 produced a significant reduction of Ti/Ttotneu and Ti/Ttotmec, by prolonging the expiratory time. Delaytrinsp and Delaytrexp were significantly shorter in NAVA, respect to PSV. AI was not influenced by the different doses of remifentanil, but it was significantly lower during NAVA, compared to PSV. In conclusion remifentanil did not affect the respiratory drive, but only respiratory timing, without differences between modes.

Influence of different interfaces on synchrony during pressure support ventilation in a pediatric setting: a bench study.

BACKGROUND: In adults and children, patient-ventilator synchrony is strongly dependent on both the ventilator settings and interface used in applying positive pressure to the airway. The aim of this bench study was to determine whether different interfaces and ventilator settings may influence patient-ventilator interaction in pediatric models of normal and mixed obstructive and restrictive respiratory conditions. METHODS: A test lung, connected to a pediatric mannequin using different interfaces (endotracheal tube [ETT], face mask, and helmet), was ventilated in pressure support ventilation mode testing 2 ventilator settings (pressurization time [Timepress]50%/cycling-off flow threshold [Trexp]25%, Timepress80%/Trexp60%), randomly applied. The test lung was set to simulate one pediatric patient with a healthy respiratory system and another with a mixed obstructive and restricted respiratory condition, at different breathing frequencies (f) (30, 40, and 50 breaths/min). We measured inspiratory trigger delay, pressurization time, expiratory trigger delay, and time of synchrony. RESULTS: At each breathing frequency, the helmet showed the longest inspiratory trigger delay compared with the ETT and face mask. At f30, the ETT had a reduced Tpress. The helmet had the shortest Tpress in the simulated child with a mixed obstructive and restricted respiratory condition, at f40 during Timepress50%/Trexp25% and at f50 during Timepress80%/Trexp60%. In the simulated child with a normal respiratory condition, the ETT presented the shortest Tpress value at f50 during Timepress80%/Trexp60%. Concerning the expiratory trigger delay, the helmet showed the best interaction at f30, but the worst at f40 and at f50. The helmet showed the shortest time of synchrony during all ventilator settings. CONCLUSIONS: The choice of the interface can influence patient-ventilator synchrony in a pediatric model breathing at increased f, thus making it more difficult to set the ventilator, particularly during noninvasive ventilation. The helmet demonstrated the worst interaction, suggesting that the face mask should be considered as the first choice for delivering noninvasive ventilation in a pediatric model.

Switches in non-invasive respiratory support strategies during acute hypoxemic respiratory failure: Need to monitoring from a retrospective observational study

Objective To explore combined non-invasive-respiratory-support (NIRS) patterns, reasons for NIRS switching, and their potential impact on clinical outcomes in acute-hypoxemic-respiratory-failure (AHRF) patients. Design Retrospective, single-center observational study. Setting Intensive Care Medicine. Patients AHRF patients (cardiac origin and respiratory acidosis excluded) underwent combined NIRS therapies such as non-invasive-ventilation (NIV) and High-Flow-Nasal-Cannula (HFNC). Interventions Patients were classified based on the first NIRS switch performed (HFNC-to-NIV or NIV-to-HFNC), and further specific NIRS switching strategies (NIV trial-like vs. Non-NIV trial-like and single vs. multiples switches) were independently evaluated. Main variables of interest Reasons for switching, NIRS failure and mortality rates. Results A total of 63 patients with AHRF were included, receiving combined NIRS, 58.7% classified in the HFNC-to-NIV group and 41.3% in the NIV-to-HFNC group. Reason for switching from HFNC to NIV was AHRF worsening (100%), while from NIV to HFNC was respiratory improvement (76.9%). NIRS failure rates were higher in the HFNC-to-NIV than in NIV-to-HFNC group (81% vs. 35%, p < 0.001). Among HFNC-to-NIV patients, there was no difference in the failure rate between the NIV trial-like and non-NIV trial-like groups (86% vs. 78%, p = 0.575) but the mortality rate was significantly lower in NIV trial-like group (14% vs. 52%, p = 0.02). Among NIV to HFNC patients, NIV failure was lower in the single switch group compared to the multiple switches group (15% vs. 53%, p = 0.039), with a shorter length of stay (5 [2–8] vs. 12 [8–30] days, p = 0.001). Conclusions NIRS combination is used in real life and both switches’ strategies, HFNC to NIV and NIV to HFNC, are common in AHRF management. Transitioning from HFNC to NIV is suggested as a therapeutic escalation and in this context performance of a NIV-trial could be beneficial. ... (AU)

Objetivo Explorar los patrones combinados de soporte-respiratorio-no-invasivo (SRNI), las razones para cambiar de SRNI y su potencial impacto en los resultados clínicos en pacientes con insuficiencia-respiratoria-aguda-hipoxémica (IRAH). Diseño Estudio observacional retrospectivo unicéntrico. Ámbito Cuidados Intensivos. Pacientes Pacientes con IRAH (excluyendo causa cardíaca y acidosis respiratoria) que recibieron tanto ventilación-no-invasiva (VNI) como cánula-nasal-de-alto-flujo (CNAF). Intervenciones Se categorizó a los pacientes según el primer cambio de SRNI realizado (CNAF-to-VNI o VNI-to-CNAF) y se evaluaron estrategias específicas de SRNI (VNI trial-like vs. Non-VNI trial-like y cambio único vs. múltiples cambios de NIRS) de manera independiente. Variables de interés principales Razones para el cambio, así como las tasas de fracaso de SRNI y la mortalidad. Resultados Un total de 63 pacientes recibieron SRNI combinado, 58,7% clasificados en el grupo CNAF-to-VNI y 41,3% en el grupo VNI-to-CNAF. Los cambios de CNAF a VNI ocurrieron por empeoramiento de la IRHA (100%) y de VNI a CNAF por mejora respiratoria (76.9%). Las tasas de fracaso de SRNI fueron mayores de CNAF a VNI que de VNI a CNAF (81% vs. 35%, p < 0.001). Dentro de los pacientes de CNAF a VNI, no hubo diferencia en las tasas de fracaso entre los grupos VNI trial-like y no-VNI trial-like (86% vs. 78%, p = 0.575), pero la mortalidad fue menor en el grupo VNI trial-like (14% vs. 52%, p = 0.02). Dentro de los pacientes de VNI a CNAF, el fracaso de VNI fue menor en grupo de cambio único vs. múltiple (15% vs. 53%, p = 0.039). Conclusiones Los cambios de estrategia de SRNI son comunes en el manejo clínico diario de la IRHA. El cambio de CNAF a VNI impresiona de ser una escalada terapéutica y en este contexto la realización de un VNI-trial puede ser beneficioso. Al contrario, cambiar de VNI a CNAF impresiona de ser una desescalada terapéutica y parece segura si no hay fracaso ... (AU)

A bench study of 2 ventilator circuits during helmet noninvasive ventilation.

OBJECTIVE: To compare helmet noninvasive ventilation (NIV), in terms of patient-ventilator interaction and performance, using 2 different circuits for connection: a double tube circuit (with one inspiratory and one expiratory line) and a standard circuit (a Y-piece connected only to one side of the helmet, closing the other side). METHODS: A manikin, connected to a test lung set at 2 breathing frequencies (20 and 30 breaths/min), was ventilated in pressure support ventilation (PSV) mode with 2 different settings, randomly applied, of the ratio of pressurization time to expiratory trigger time (T(press)/T(exp-trigger)) 50%/25%, default setting, and T(press)/T(exp-trigger) 80%/60%, fast setting, through a helmet. The helmet was connected to the ventilator randomly with the double and the standard circuit. We measured inspiratory trigger delay (T(insp-delay)), expiratory trigger delay (T(exp-delay)), T(press)), time of synchrony (T(synch)), trigger pressure drop, inspiratory pressure-time product (PTP), PTP at 300 ms and 500 ms, and PTP at 500 ms expressed as percentage of an ideal PTP500 (PTP500 index). RESULTS: At both breathing frequencies and ventilator settings, helmet NIV with the double tube circuit showed better patient-ventilator interaction, with shorter T(insp-delay), T(exp-delay), and T(press); longer T(synch); and higher PTP300, PTP500, and PTP500 index (all P < .01). CONCLUSIONS: The double tube circuit had significantly better patient-ventilator interaction and a lower rate of wasted effort at 30 breaths/min.