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Sistemas de bucle cerrado en pacientes pediátricos con ventilación mecánica: últimas pruebas

Artículo

Autor: Caroline Brown

Fecha: 07.12.2022

Dos estudios recientes han investigado el uso de un modo de ventilación de bucle cerrado y el control de bucle cerrado de la fracción de oxígeno inspirado (FiO2) en pacientes pediátricos.
Sistemas de bucle cerrado en pacientes pediátricos con ventilación mecánica: últimas pruebas

Si bien actualmente existen pruebas abundantes sobre el uso de sistemas de bucle cerrado en adultos, los datos disponibles sobre su uso en pacientes pediátricos son muy limitados. De manera similar, existen pocas pruebas sobre el efecto de la presión de trabajo (∆P) en los resultados de niños, algo que en adultos se ha determinado como la variable más estrechamente asociada con la mortalidad en pacientes adultos con SDRA (Amato MB, Meade MO, Slutsky AS, et al. Driving pressure and survival in the acute respiratory distress syndrome. N Engl J Med. 2015;372(8):747‑755. doi:10.1056/NEJMsa14106391). Un reciente estudio de cohortes retrospectivo en niños con insuficiencia respiratoria hipoxémica aguda con ventilación de ∆P alta (≥ 15 cmH2O) o ∆P baja (< 15 cmH2O) no descubrió ninguna diferencia en cuanto a la mortalidad, pero sí un descenso considerable en la morbilidad en el grupo de ∆P baja. Los que pertenecían al grupo de ∆P baja también pasaron más días sin el respirador y sus estancias en la UCI y el hospital fueron más cortas (Rauf A, Sachdev A, Venkataraman ST, Dinand V. Dynamic Airway Driving Pressure and Outcomes in Children With Acute Hypoxemic Respiratory Failure. Respir Care. 2021;66(3):403‑409. doi:10.4187/respcare.080242). Un equipo de investigadores del Hospital de Formación e Investigación de Enfermedades y Cirugía Pediátricas Dr. Behçet Uz de Izmir, Turquía, se dispuso a comparar la presión de trabajo generada por la ventilación asistida adaptable (ASV 1.1) en pacientes pediátricos con insuficiencia respiratoria con uno de los modos más usados en pacientes pediátricos, la ventilación obligatoria controlada con ventilación de presión adaptable (APV‑CMV) (Ceylan G, Topal S, Atakul G, et al. Randomized crossover trial to compare driving pressures in a closed-loop and a conventional mechanical ventilation mode in pediatric patients. Pediatr Pulmonol. 2021;56(9):3035-3043. doi:10.1002/ppul.255613).

ASV 1.1 frente a APV‑CMV

En este ensayo controlado aleatorizado participaron 26 pacientes con una edad media de 16 meses y con estados pulmonares heterogéneos (restrictivo, obstructivo y normal). Recibieron ventilación durante dos periodos de 60 minutos, uno en ASV 1.1 y el otro en APV‑CMV. Se mantuvo la misma ventilación por minuto en los dos modos. APV‑CMV ajusta la presión aplicada para evitar volúmenes tidales bajos o altos cuando cambia la compliance, pero mantiene el volumen tidal objetivo (VT) fijado por el médico siempre que la presión permanezca por debajo del límite establecido. Sin embargo, ASV determina la combinación óptima de frecuencia respiratoria (FR) y VT para el volumen por minuto fijado por el médico basado en un análisis respiración a respiración de la mecánica respiratoria del paciente. Este comportamiento coincide con la recomendación de la Pediatric Acute Lung Injury Consensus Conference de seleccionar el VT en función de la gravedad de la enfermedad de cada paciente (Pediatric Acute Lung Injury Consensus Conference Group. Pediatric acute respiratory distress syndrome: consensus recommendations from the Pediatric Acute Lung Injury Consensus Conference. Pediatric Critical Care Med. 2015;16(5):428-439. doi:10.1097/PCC.00000000000003504). Por lo tanto, la hipótesis de los investigadores es que los ajustes seleccionados automáticamente por ASV 1.1 reducirán en mayor grado la presión de trabajo que el modo APV-CMV fijado por el médico.

Presiones y volúmenes tidales inferiores

La presión de trabajo se calculó como la diferencia entre la presión de meseta y la presión positiva al final de la espiración total (PEEP total). Estos parámetros se midieron mediante una maniobra de pausa al final de la inspiración y otra al final de la espiración, respectivamente. Se descubrió que la ∆P media durante la fase de ASV 1.1 era considerablemente menor que la producida durante el periodo de APV‑CMV (10,4 [8,5−12,1 {IQR}]) y 12,4 [10,5−15,3 {IQR}] cmH2O, respectivamente [p < 0,001]).  Además, el volumen tidal medio fue considerablemente más bajo en el grupo de ASV 1.1 (6,4 ml/kg frente a 7,9 ml/kg; p < 0,001), como también lo fueron la presión inspiratoria máxima (19,1 cmH2O frente a 22,5 cmH2O; p = 0,001) y la presión de meseta (16,9 cmH2O frente a 18,4 cmH2O; p < 0,001). El CO2 al final del volumen tidal fue considerablemente mayor (41 mmHg frente a 38 mmHg; p = 0,001). En los dos grupos ninguno de los parámetros de ventilación ni de los valores de gases en la sangre arterial superaron las recomendaciones actuales para la ventilación mecánica en pacientes pediátricos, por lo que todos los pacientes permanecieron dentro de zonas seguras en todo momento (Ceylan G, Topal S, Atakul G, et al. Randomized crossover trial to compare driving pressures in a closed-loop and a conventional mechanical ventilation mode in pediatric patients. Pediatr Pulmonol. 2021;56(9):3035-3043. doi:10.1002/ppul.255613). 

Si bien es posible obtener resultados similares en un control de volumen con presión regulada al reducir el VT objetivo, para ello es necesario contar con personal suficiente que realice los ajustes. Especialmente cuando los recursos son limitados, ASV 1.1 ofrece la ventaja de ajustar automáticamente el VT y la FR respecto a un cambio en la mecánica respiratoria en el momento en que este se produce. Aun en el caso de que se cuente con recursos suficientes, resulta evidente que la valoración automática de la ventilación de manera continua puede reducir la carga del personal de la UCI.

Valoración de FiO2 manual frente a bucle cerrado

En el segundo estudio, los mismos investigadores compararon la valoración de FiO2 manual con el uso de un sistema de valoración de FiO2 de bucle cerrado en pacientes pediátricos (Soydan E, Ceylan G, Topal S, et al. Automated closed‑loop FiO2 titration increases the percentage of time spent in optimal zones of oxygen saturation in pediatric patients-A randomized crossover clinical trial. Front Med (Lausanne). 2022;9:969218. Publicado el 25 de agosto de 2022. doi:10.3389/fmed.2022.9692185). Aunque un metaanálisis en bebés prematuros sometidos a una terapia respiratoria de presión positiva ha sugerido una asociación entre la valoración de FiO2 automática y un mayor tiempo empleado en los intervalos objetivo de saturación de oxígeno (SpO2) (Mitra S, Singh B, El‑Naggar W, McMillan DD. Automated versus manual control of inspired oxygen to target oxygen saturation in preterm infants: a systematic review and meta‑analysis. J Perinatol. 2018;38(4):351‑360. doi:10.1038/s41372‑017‑0037‑z6), el efecto en pacientes pediátricos no está claro. En un estudio piloto anterior en una cohorte pequeña de niños con ventilación mecánica, se descubrió que la ASV junto con un control de bucle cerrado de la ventilación y la oxigenación les mantiene con una ventilación normal (número de respiraciones normales recogidas dividido por el número total de respiraciones recogidas) durante un porcentaje similar de tiempo al de la ventilación de presión de soporte (Jouvet P, Eddington A, Payen V, et al. A pilot prospective study on closed loop controlled ventilation and oxygenation in ventilated children during the weaning phase. Crit Care. 2012;16(3):R85. Publicado el 16 de mayo de 2012. doi:10.1186/cc113437). 

El estudio actual incluía una cohorte de 30 pacientes con una edad media de 21 meses y estados pulmonares heterogéneos, 12 de ellos con SDRA pediátrica (Soydan E, Ceylan G, Topal S, et al. Automated closed‑loop FiO2 titration increases the percentage of time spent in optimal zones of oxygen saturation in pediatric patients-A randomized crossover clinical trial. Front Med (Lausanne). 2022;9:969218. Publicado el 25 de agosto de 2022. doi:10.3389/fmed.2022.9692185). Todos los pacientes recibieron ventilación en ASV 1.1 durante dos fases de 2,5 horas cada una. Durante la primera fase, se activó el controlador de FiO2 automático y durante la segunda, se valoró manualmente la FiO2. Los primeros 30 minutos de cada fase se consideraron un periodo de preinclusión; los datos se recopilaron durante dos horas en cada fase. La ventilación por minuto y la PEEP se mantuvieron en el mismo nivel durante las dos fases. El criterio de valoración principal fue el porcentaje de tiempo que los pacientes pasaron en zonas de SpO2 óptimas predefinidas, mientras que los criterios secundarios incluyeron el tiempo que pasaron en zonas aceptables, subóptimas e inaceptables, así como el número de cambios de FiO2 por paciente.

Más tiempo empleado en el intervalo de SpO2 óptimo

Los resultados demostraron que los pacientes pasaron considerablemente más tiempo en el intervalo óptimo con el controlador de FiO2 activado que con la valoración de FiO2 manual (96,1 % [93,7‑98,6 {IQR}] frente al 78,4 % [51,3‑94,8 {IQR}; [p < 0,001]). Además, también pasaron bastante menos tiempo en zonas bajas inaceptables, subóptimas y aceptables, y en zonas altas subóptimas con el control de FiO2 automático (valores p de 0,032, 0,008, 0,004 y 0,001, respectivamente). Un hallazgo adicional fue el porcentaje medio menor de FiO2 con el control de FiO2 automático. Los resultados obtenidos en un estudio realizado en niños que recibieron VV‑ECMO en el que se estableció una posible relación entre una FiO2 más alta y la mortalidad (Friedman ML, Barbaro RP, Bembea MM, et al. Mechanical Ventilation in Children on Venovenous ECMO. Respir Care. 2020;65(3):271-280. Doi:10.4187/respcare.072148) llevan a deducir que una FiO2 más baja con control de FiO2 de bucle cerrado podría tener un efecto positivo en los resultados.

Eficiencia de sistemas de bucle cerrado

En cuanto a la eficiencia, los autores han destacado diversos aspectos diferentes. En primer lugar, el número muy superior de ajustes por paciente que realizó el controlador de FiO2 en comparación con los manuales (52 [11,8‑67 {IQR}] frente a 1 [0‑2 {IQR}], p < 0,001). Si hacer solo un cambio cada dos horas en 30 pacientes puede llegar a consumir los recursos del hospital, realizar varios cambios manualmente en un periodo de dos horas es poco viable. En segundo lugar, tanto el índice de oxigenación medio como el uso de O2 medio fueron inferiores durante la fase automática en comparación con la manual, lo que representa un uso más eficiente del oxígeno terapéutico. 

Además de aportar información adicional a las pruebas tan limitadas disponibles sobre el uso de los modos de ventilación automática en pacientes pediátricos, estos dos estudios demuestran las ventajas potenciales de la automatización en cuanto a eficiencia. Los modos de ventilación automática no solo permiten un mayor número de ajustes como respuesta a los cambios en el estado del paciente, sino que también reducen la carga de trabajo del personal sanitario. Este aspecto ha cobrado mucha más importancia, especialmente durante la reciente situación de pandemia.

Notas al pie

Referencias

  1. 1. Amato MB, Meade MO, Slutsky AS, et al. Driving pressure and survival in the acute respiratory distress syndrome. N Engl J Med. 2015;372(8):747‑755. doi:10.1056/NEJMsa1410639
  2. 2. Rauf A, Sachdev A, Venkataraman ST, Dinand V. Dynamic Airway Driving Pressure and Outcomes in Children With Acute Hypoxemic Respiratory Failure. Respir Care. 2021;66(3):403‑409. doi:10.4187/respcare.08024
  3. 3. Ceylan G, Topal S, Atakul G, et al. Randomized crossover trial to compare driving pressures in a closed‑loop and a conventional mechanical ventilation mode in pediatric patients. Pediatr Pulmonol. 2021;56(9):3035‑3043. doi:10.1002/ppul.25561
  4. 4. Pediatric Acute Lung Injury Consensus Conference Group. Pediatric acute respiratory distress syndrome: consensus recommendations from the Pediatric Acute Lung Injury Consensus Conference. Pediatr Crit Care Med. 2015;16(5):428‑439. doi:10.1097/PCC.0000000000000350
  5. 5. Soydan E, Ceylan G, Topal S, et al. Automated closed‑loop FiO2 titration increases the percentage of time spent in optimal zones of oxygen saturation in pediatric patients-A randomized crossover clinical trial. Front Med (Lausanne). 2022;9:969218. Published 2022 Aug 25. doi:10.3389/fmed.2022.969218
  6. 6. Mitra S, Singh B, El‑Naggar W, McMillan DD. Automated versus manual control of inspired oxygen to target oxygen saturation in preterm infants: a systematic review and meta‑analysis. J Perinatol. 2018;38(4):351‑360. doi:10.1038/s41372‑017‑0037‑z
  7. 7. Jouvet P, Eddington A, Payen V, et al. A pilot prospective study on closed loop controlled ventilation and oxygenation in ventilated children during the weaning phase. Crit Care. 2012;16(3):R85. Published 2012 May 16. doi:10.1186/cc11343
  8. 8. Friedman ML, Barbaro RP, Bembea MM, et al. Mechanical Ventilation in Children on Venovenous ECMO. Respir Care. 2020;65(3):271‑280. doi:10.4187/respcare.07214

Driving pressure and survival in the acute respiratory distress syndrome.

Amato MB, Meade MO, Slutsky AS, et al. Driving pressure and survival in the acute respiratory distress syndrome. N Engl J Med. 2015;372(8):747‑755. doi:10.1056/NEJMsa1410639



BACKGROUND

Mechanical‑ventilation strategies that use lower end‑inspiratory (plateau) airway pressures, lower tidal volumes (VT), and higher positive end‑expiratory pressures (PEEPs) can improve survival in patients with the acute respiratory distress syndrome (ARDS), but the relative importance of each of these components is uncertain. Because respiratory‑system compliance (CRS) is strongly related to the volume of aerated remaining functional lung during disease (termed functional lung size), we hypothesized that driving pressure (ΔP=VT/CRS), in which VT is intrinsically normalized to functional lung size (instead of predicted lung size in healthy persons), would be an index more strongly associated with survival than VT or PEEP in patients who are not actively breathing.

METHODS

Using a statistical tool known as multilevel mediation analysis to analyze individual data from 3562 patients with ARDS enrolled in nine previously reported randomized trials, we examined ΔP as an independent variable associated with survival. In the mediation analysis, we estimated the isolated effects of changes in ΔP resulting from randomized ventilator settings while minimizing confounding due to the baseline severity of lung disease.

RESULTS

Among ventilation variables, ΔP was most strongly associated with survival. A 1-SD increment in ΔP (approximately 7 cm of water) was associated with increased mortality (relative risk, 1.41; 95% confidence interval [CI], 1.31 to 1.51; P<0.001), even in patients receiving "protective" plateau pressures and VT (relative risk, 1.36; 95% CI, 1.17 to 1.58; P<0.001). Individual changes in VT or PEEP after randomization were not independently associated with survival; they were associated only if they were among the changes that led to reductions in ΔP (mediation effects of ΔP, P=0.004 and P=0.001, respectively).

CONCLUSIONS

We found that ΔP was the ventilation variable that best stratified risk. Decreases in ΔP owing to changes in ventilator settings were strongly associated with increased survival. (Funded by Fundação de Amparo e Pesquisa do Estado de São Paulo and others.).

Dynamic Airway Driving Pressure and Outcomes in Children With Acute Hypoxemic Respiratory Failure.

Rauf A, Sachdev A, Venkataraman ST, Dinand V. Dynamic Airway Driving Pressure and Outcomes in Children With Acute Hypoxemic Respiratory Failure. Respir Care. 2021;66(3):403‑409. doi:10.4187/respcare.08024



BACKGROUND

Limited adult data suggest that airway driving pressure might better reflect the potential risk for lung injury than tidal volume based on ideal body weight, and the parameter correlates with mortality in ARDS. There is a lack of data about the effect of driving pressure on mortality in pediatric ARDS. This study aimed to evaluate the effect of driving pressure on morbidity and mortality of children with acute hypoxemic respiratory failure.

METHODS

This retrospective cohort study was performed in a tertiary level pediatric ICU. Children who received invasive mechanical ventilation for acute hypoxemic respiratory failure (defined as [Formula: see text] < 300 within 24 h after intubation), in a 2‑y period were included. The cohort was divided into 2 groups based on the highest dynamic driving pressure (ΔP, calculated as the difference between peak inspiratory pressure and PEEP) in the first 24 h, with a cutoff value of 15 cm H2O.

RESULTS

Of the 380 children who were mechanically ventilated during the study period, 101 children who met eligibility criteria were enrolled. Common diagnoses were pneumonia (n = 51), severe sepsis (n = 24), severe dengue (n = 10), and aspiration pneumonia (n = 7). In comparison to the group with high ΔP (ie, ≥ 15 cm H2O), children in the group with low ΔP (ie, < 15 cm H2O) had significantly lower median (interquartile range) duration of ventilation (5 [4-6] d vs 8 [6-11] d, P < .001], ICU length of stay (6 [5-8] d vs 12 [8-15] d, P < .001], and more ventilator-free days at day 28 (23 [20-24] vs 17 [0-22] d, P < .001). Logistic regression analysis also suggested driving pressure as an independent predictor of morbidity after adjusting for confounding variables. However, there was no statistically significant difference in mortality between the 2 groups (17% in low ΔP vs 24% in high ΔP, P = .38). Subgroup analysis of 65 subjects who fulfilled ARDS criteria yielded similar results with respect to mortality and morbidity.

CONCLUSIONS

Below a threshold of 15 cm H2O, ΔP was associated with significantly decreased morbidity in children with acute hypoxemic respiratory failure.

Randomized crossover trial to compare driving pressures in a closed‑loop and a conventional mechanical ventilation mode in pediatric patients.

Ceylan G, Topal S, Atakul G, et al. Randomized crossover trial to compare driving pressures in a closed‑loop and a conventional mechanical ventilation mode in pediatric patients. Pediatr Pulmonol. 2021;56(9):3035‑3043. doi:10.1002/ppul.25561



INTRODUCTION

In mechanically ventilated patients, driving pressure (ΔP) represents the dynamic stress applied to the respiratory system and is related to ICU mortality. An evolution of the Adaptive Support Ventilation algorithm (ASV® 1.1) minimizes inspiratory pressure in addition to minimizing the work of breathing. We hypothesized that ASV 1.1 would result in lower ΔP than the ΔP measured in APV‑CMV (controlled mandatory ventilation with adaptive pressure ventilation) mode with physician‑tailored settings. The aim of this randomized crossover trial was therefore to compare ΔP in ASV 1.1 with ΔP in physician‑tailored APV‑CMV mode.

METHODS

Pediatric patients admitted to the PICU with heterogeneous-lung disease were enrolled if they were ventilated invasively with no detectable respiratory effort, hemodynamic instability, or significant airway leak around the endotracheal tube. We compared two 60-min periods of ventilation in APV-CMV and ASV 1.1, which were determined by randomization and separated by 30-min washout periods. Settings were adjusted to reach the same minute ventilation in both modes. ΔP was calculated as the difference between plateau pressure and total PEEP measured using end-inspiratory and end-expiratory occlusions, respectively.

RESULTS

There were 26 patients enrolled with a median age of 16 (9-25 [IQR]) months. The median ΔP for these patients was 10.4 (8.5-12.1 [IQR]) and 12.4 (10.5-15.3 [IQR]) cmH2O in the ASV 1.1 and APV-CMV periods, respectively (p < .001). The median tidal volume (VT) selected by the ASV 1.1 algorithm was 6.4 (5.1-7.3 [IQR]) ml/kg and RR was 41 (33 50 [IQR]) b/min, whereas the median of the same values for the APV-CMV period was 7.9 (6.8-8.3 [IQR]) ml/kg and 31 (26-41[IQR]) b/min, respectively. In both ASV 1.1 and APV-CMV modes, the highest ΔP was used to ventilate those patients with restrictive lung conditions at baseline.

CONCLUSION

In this randomized crossover trial, ΔP in ASV 1.1 was lower compared to ΔP in physician-tailored APV-CMV mode in pediatric patients with different lung conditions. The use of ASV 1.1 may therefore result in continued, safe ventilation in a heterogeneous pediatric patient group.

Pediatric acute respiratory distress syndrome: consensus recommendations from the Pediatric Acute Lung Injury Consensus Conference.

Pediatric Acute Lung Injury Consensus Conference Group. Pediatric acute respiratory distress syndrome: consensus recommendations from the Pediatric Acute Lung Injury Consensus Conference. Pediatr Crit Care Med. 2015;16(5):428‑439. doi:10.1097/PCC.0000000000000350



OBJECTIVE

To describe the final recommendations of the Pediatric Acute Lung Injury Consensus Conference.

DESIGN

Consensus conference of experts in pediatric acute lung injury.

SETTING

Not applicable.

SUBJECTS

PICU patients with evidence of acute lung injury or acute respiratory distress syndrome.

INTERVENTIONS

None.

METHODS

A panel of 27 experts met over the course of 2 years to develop a taxonomy to define pediatric acute respiratory distress syndrome and to make recommendations regarding treatment and research priorities. When published, data were lacking a modified Delphi approach emphasizing strong professional agreement was used.

MEASUREMENTS AND MAIN RESULTS

A panel of 27 experts met over the course of 2 years to develop a taxonomy to define pediatric acute respiratory distress syndrome and to make recommendations regarding treatment and research priorities. When published data were lacking a modified Delphi approach emphasizing strong professional agreement was used. The Pediatric Acute Lung Injury Consensus Conference experts developed and voted on a total of 151 recommendations addressing the following topics related to pediatric acute respiratory distress syndrome: 1) Definition, prevalence, and epidemiology; 2) Pathophysiology, comorbidities, and severity; 3) Ventilatory support; 4) Pulmonary‑specific ancillary treatment; 5) Nonpulmonary treatment; 6) Monitoring; 7) Noninvasive support and ventilation; 8) Extracorporeal support; and 9) Morbidity and long‑term outcomes. There were 132 recommendations with strong agreement and 19 recommendations with weak agreement. Once restated, the final iteration of the recommendations had none with equipoise or disagreement.

CONCLUSIONS

The Consensus Conference developed pediatric-specific definitions for acute respiratory distress syndrome and recommendations regarding treatment and future research priorities. These are intended to promote optimization and consistency of care for children with pediatric acute respiratory distress syndrome and identify areas of uncertainty requiring further investigation.

Automated closed‑loop FiO2 titration increases the percentage of time spent in optimal zones of oxygen saturation in pediatric patients‑A randomized crossover clinical trial.

Soydan E, Ceylan G, Topal S, et al. Automated closed‑loop FiO2 titration increases the percentage of time spent in optimal zones of oxygen saturation in pediatric patients-A randomized crossover clinical trial. Front Med (Lausanne). 2022;9:969218. Published 2022 Aug 25. doi:10.3389/fmed.2022.969218



Introduction

We aimed to compare automated ventilation with closed‑loop control of the fraction of inspired oxygen (FiO2) to automated ventilation with manual titrations of the FiO2 with respect to time spent in predefined pulse oximetry (SpO2) zones in pediatric critically ill patients.

Methods

This was a randomized crossover clinical trial comparing Adaptive Support Ventilation (ASV) 1.1 with use of a closed-loop FiO2 system vs. ASV 1.1 with manual FiO2 titrations. The primary endpoint was the percentage of time spent in optimal SpO2 zones. Secondary endpoints included the percentage of time spent in acceptable, suboptimal and unacceptable SpO2 zones, and the total number of FiO2 changes per patient.

Results

We included 30 children with a median age of 21 (11-48) months; 12 (40%) children had pediatric ARDS. The percentage of time spent in optimal SpO2 zones increased with use of the closed-loop FiO2 controller vs. manual oxygen control [96.1 (93.7-98.6) vs. 78.4 (51.3-94.8); P < 0.001]. The percentage of time spent in acceptable, suboptimal and unacceptable zones decreased. Findings were similar with the use of closed-loop FiO2 controller compared to manual titration in patients with ARDS [95.9 (81.6-98.8) vs. 78 (49.5-94.8) %; P = 0.027]. The total number of closed-loop FiO2 changes per patient was 52 (11.8-67), vs. the number of manual changes 1 (0-2), (P < 0.001).

Conclusion

In this randomized crossover trial in pediatric critically ill patients under invasive ventilation with ASV, use of a closed-loop control of FiO2 titration increased the percentage of time spent within in optimal SpO2 zones, and increased the total number of FiO2 changes per patient.

Clinical trial registration

ClinicalTrials.gov, identifier: NCT04568642.

Automated versus manual control of inspired oxygen to target oxygen saturation in preterm infants: a systematic review and meta‑analysis.

Mitra S, Singh B, El‑Naggar W, McMillan DD. Automated versus manual control of inspired oxygen to target oxygen saturation in preterm infants: a systematic review and meta‑analysis. J Perinatol. 2018;38(4):351‑360. doi:10.1038/s41372‑017‑0037‑z



OBJECTIVES

To conduct a systematic review of clinical trials comparing automated versus manual fraction of inspired oxygen (FiO2) control to target oxygen saturation (SpO2) in preterm infants.

DESIGN

The authors searched MEDLINE, Embase, CENTRAL, and CINAHL from inception upto December 2016, reviewed conference proceedings and sought results of unpublished trials. Studies were included if automated FiO2 control was compared to manual control in preterm infants on positive pressure respiratory support. The primary outcome was percentage of time spent within the target SpO2 range. Summary mean differences (MD) were computed using random effects model.

RESULTS

Out of 276 identified studies 10 met the inclusion criteria. Automated FiO2 control significantly improved time being spent within the target SpO2 range [MD: 12.8%; 95% CI: 6.5‑19.2%; I2 = 90%]. Periods of hyperoxia (MD:‑8.8%; 95% CI: ‑15 to ‑2.7%), severe hypoxia(SpO2  < 80%)(MD: ‑0.9%;95%CI: ‑1.5 to ‑0.4%) and hypoxic events (MD: ‑5.6%; 95% CI: ‑9.1 to ‑2.1%) were significantly reduced with automated control.

CONCLUSION

Automated FiO2 adjustment provides significant improvement of time in target saturations, reduces periods of hyperoxia, and severe hypoxia in preterm infants on positive pressure respiratory support.

A pilot prospective study on closed loop controlled ventilation and oxygenation in ventilated children during the weaning phase.

Jouvet P, Eddington A, Payen V, et al. A pilot prospective study on closed loop controlled ventilation and oxygenation in ventilated children during the weaning phase. Crit Care. 2012;16(3):R85. Published 2012 May 16. doi:10.1186/cc11343



INTRODUCTION

The present study is a pilot prospective safety evaluation of a new closed loop computerised protocol on ventilation and oxygenation in stable, spontaneously breathing children weighing more than 7 kg, during the weaning phase of mechanical ventilation.

METHODS

Mechanically ventilated children ready to start the weaning process were ventilated for five periods of 60 minutes in the following order: pressure support ventilation, adaptive support ventilation (ASV), ASV plus a ventilation controller (ASV‑CO2), ASV‑CO2 plus an oxygenation controller (ASV‑CO2‑O2) and pressure support ventilation again. Based on breath‑by‑breath analysis, the percentage of time with normal ventilation as defined by a respiratory rate between 10 and 40 breaths/minute, tidal volume > 5 ml/kg predicted body weight and end‑tidal CO2 between 25 and 55 mmHg was determined. The number of manipulations and changes on the ventilator were also recorded.

RESULTS

Fifteen children, median aged 45 months, were investigated. No adverse event and no premature protocol termination were reported. ASV-CO2 and ASV-CO2-O2 kept the patients within normal ventilation for, respectively, 94% (91 to 96%) and 94% (87 to 96%) of the time. The tidal volume, respiratory rate, peak inspiratory airway pressure and minute ventilation were equivalent for all modalities, although there were more automatic setting changes in ASV-CO2 and ASV-CO2-O2. Positive end-expiratory pressure modifications by ASV-CO2-O2 require further investigation.

CONCLUSION

Over the short study period and in this specific population, ASV-CO2 and ASV-CO2-O2 were safe and kept the patient under normal ventilation most of the time. Further research is needed, especially for positive end-expiratory pressure modifications by ASV-CO2-O2.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT01095406.

Mechanical Ventilation in Children on Venovenous ECMO.

Friedman ML, Barbaro RP, Bembea MM, et al. Mechanical Ventilation in Children on Venovenous ECMO. Respir Care. 2020;65(3):271‑280. doi:10.4187/respcare.07214



BACKGROUND

Venovenous extracorporeal membrane oxygenation (VV‑ECMO) is used when mechanical ventilation can no longer support oxygenation or ventilation, or if the risk of ventilator‑induced lung injury is considered excessive. The optimum mechanical ventilation strategy once on ECMO is unknown. We sought to describe the practice of mechanical ventilation in children on VV‑ECMO and to determine whether mechanical ventilation practices are associated with clinical outcomes.

METHODS

We conducted a multicenter retrospective cohort study in 10 pediatric academic centers in the United States. Children age 14 d through 18 y on VV-ECMO from 2011 to 2016 were included. Exclusion criteria were preexisting chronic respiratory failure, primary diagnosis of asthma, cyanotic heart disease, or ECMO as a bridge to lung transplant.

RESULTS

Conventional mechanical ventilation was used in about 75% of children on VV-ECMO; the remaining subjects were managed with a variety of approaches. With the exception of PEEP, there was large variation in ventilator settings. Ventilator mode and pressure settings were not associated with survival. Mean ventilator FIO2 on days 1-3 was higher in nonsurvivors than in survivors (0.5 vs 0.4, P = .009). In univariate analysis, other risk factors for mortality were female gender, higher Pediatric Risk Estimate Score for Children Using Extracorporeal Respiratory Support (Ped-RESCUERS), diagnosis of cancer or stem cell transplant, and number of days intubated prior to initiation of ECMO (all P < .05). In multivariate analysis, ventilator FIO2 was significantly associated with mortality (odds ratio 1.38 for each 0.1 increase in FIO2 , 95% CI 1.09-1.75). Mortality was higher in subjects on high ventilator FIO2 (≥ 0.5) compared to low ventilator FIO2 (> 0.5) (46% vs 22%, P = .001).

CONCLUSIONS

Ventilator mode and some settings vary in practice. The only ventilator setting associated with mortality was FIO2 , even after adjustment for disease severity. Ventilator FIO2 is a modifiable setting that may contribute to mortality in children on VV-ECMO.