Driving Pressure and Mortality: in the Pediatric Intensive Care Unit (PICU)
Condition: ARDS, Human; Respiratory Failure
MeSH terms: Respiratory Insufficiency; Respiratory Distress Syndrome
Study type: Observational [Patient Registry]

Summary: 
      Respiratory failure is one of the most common causes of both hospitalization and mortality in
      patients in the pediatric intensive care unit (PICU). Recently, it is recommended to target
      driving pressure (ΔP) in patients with ARDS to achieve better results with the administration
      of optimal mechanical ventilation. In many studies, higher ΔP was associated with mortality
      in adult ARDS patients; non-ARDS patients' studies showing the relationship between driving
      pressure and mortality are few, but contradictory results have come out.

      This study aimed to determine whether ΔP was associated with mortality in pediatric patients
      diagnosed as pARDS and non-pARDS who received mechanical ventilation support due to
      respiratory failure. Patients who received invasive mechanical ventilation support due to
      respiratory failure in the pediatric intensive care unit over 1 month and under 18 years were
      included in our study Driving pressure was significantly associated with an increased risk of
      mortality among mechanically ventilated both pARDS and non-pARDS patients. Future prospective
      randomized clinical trials are needed to determine a protocol targeting DP can be developed
      and defining optimum cutoff values.
    

Detailed description: 
      Respiratory failure is one of the most common causes of both hospitalization and mortality in
      patients in the pediatric intensive care unit (PICU). Recently, it is recommended to target
      driving pressure (ΔP) in patients with ARDS to achieve better results with the administration
      of optimal mechanical ventilation. ΔP is calculated as the difference between Plateau
      pressure (Pplat) and positive end-expiratory pressure (PEEP) and is determined by the ratio
      of the tidal volume to the compliance of the respiratory system (ΔP = Pplat - PEEP = VT/CRS).
      ΔP estimates how much mechanical strain (dynamic strain) the tidal volume causes in the lung.
      It is a non-invasive and simple method and can be easily calculated at the bedside. In many
      studies, higher ΔP was associated with mortality in adult ARDS patients; non-ARDS patients'
      studies showing the relationship between driving pressure and mortality are few, but
      contradictory results have come out.

      This study aimed to determine whether ΔP was associated with mortality in pediatric patients
      diagnosed as pARDS and non-pARDS who received mechanical ventilation support due to
      respiratory failure.

      Single-center, prospective, observational study of patients admitted to pediatric intensive
      care units (PICU) in Turkey. In our study, the ethics committee was approved by The Health
      Sciences University Izmir Behcet Uz Child Health and Diseases education and research hospital
      ethics committee (protocol no: 2019-344).In our study, patients who received invasive
      mechanical ventilation support due to respiratory failure in the pediatric intensive care
      unit over 1 month and under 18 years were included in the study between March 2018 and April
      2020. Mechanically ventilated patients (via ETT or trachestomy) were recorded for patients
      whose ventilation duration lasted at least 24 hours. We divided the patients into two groups
      by calculating the oxygenation index (OI): [mean airway pressure(MAP) × fraction of inspired
      oxygen (FiO2) ]/ partial pressure of oxygen in arterial blood (PaO2) × 100) used in the
      classification of PALICC, including ARDS and non-ARDS. PARDS definition was also identified
      based on the PALICC criteria. Data were prospectively recorded on day 1 including patient
      demographics, ventilator settings (VT, VT / ideal body weight (IBW), respiratory rate (RR),
      peak inspiratory pressure (PIP), plateau pressure (Pplat), mean airway pressure (Pmean),
      minute volume (VE), end-expiratory pressure (PEEP), static compliance (Cstat), fraction of
      inspired oxygen FIO2, inspiratory time ( IT), expiratory time (ET) and we calculated
      oxygenation index (OI), cstat (VT/∆P), partial pressure of oxygen in arterial blood (PaO2)
      /FiO2, driving pressure (ΔP), the pediatric index of mortality (PRISM) III scores and
      pediatric sequential organ failure assessment (pSOFA) scores.

      All patients were ventilated with volume control (VCV) or pressure control (PCV) mode during
      the hospitalization. İn order to measure the driving pressure of patients, Pplat was measured
      in the mechanical ventilator every 12 hours using an inspiratory hold maneuver. The average
      Pplat was calculated using the mean of 2 measurements within 24 hours. Then, the total PEEP
      was measured by expiratory hold maneuver and ΔP was calculated with the Pplat-PEEP formula.
      Patients were followed for 30 days until hospital discharge. We used ΔP compared to other
      mechanic ventilator parameters between survivors and non-survivors at day 30. Besides, ΔP and
      other parameters of patients in the ARDS and non-ARDS groups were compared with their 30-day
      mortality.

      Statistical Analyses Primarily, we evaluated the relationship between ΔP and mortality in
      patients with ARDS and non-ARDS. Our second target was to evaluate the relationship between
      mortality and ΔP and other mechanical ventilator parameters.

      Driving pressure and other lung dynamics; according to the type and distribution of the data
      was compared with chi-square, Wilcoxon, Independent-T-test or Mann-Whitney-U test and p <0.05
      was considered statistically significant. The strength of the association between the two
      variables was measured using the correlation coefficient. We used Pearson correlation to
      parametric variable and Spearman correlation to the nonparametric variable to detect
      covariances before logistic regression analysis. We evaluated with spearman's correlation
      analysis to detect covariances before logistic regression analysis. Parameters found
      significant with mortality in univariate analyzes were evaluated by Logistic Regression
      analysis. (odds ratio [OR] and 95 % confidence intervals [CI]) Model fit was assessed using
      Hosmer-Lemeshow statistics.

      For the multivariable analysis, we identified covariates that may be associated with
      mortality. VT /IBW, PaO2, OI, FiO2, PRISM III score, Days of ventilation and pSOFA score were
      not collinear with ΔP. We did not include Pplat, PIP, Pmean in logistic regression models
      containing ΔP given concerns for collinearity Individual covariates included age, gender,
      PRISM III score, PaO2, OI, FiO2, Days of ventilation and pSOFA score. We created 3 other
      modeling analyzes for Pplat, PIP, Pmean, because of collinearity with driving pressure. We
      evaluated this model to determine the best parameter related to mortality in whole patients
      under mechanical ventilation support due to respiratory failure. ΔP cut off (13 cmH2O) values
      in adult studies in the literature were categorized and mortality was estimated by a receiver
      operating characteristic (ROC). We performed all statistical analyses using IBM SPSS
      Statistics for Windows version 22 (Armonk, NY) for analysis.

      Mechanical ventilation is one of the most common indications for admission to a pediatric
      intensive care unit (PICU), with up to 64% of admitted children requiring mechanical
      ventilation. Driving pressure (ΔP), which is calculated as end-inspiratory plateau pressure
      (Pplat) minus applied positive end-expiratory pressure (PEEP) and is equivalent to the ratio
      between the VT and compliance of the respiratory system, can reduce mortality with children
      who received mechanical ventilator support due to respiratory failure. ΔP is a non-invasive
      and simple method and can be easily calculated at the bedside.

      Recent data in the adult ARDS population have shown that the ΔP is most related to mortality.
      Our study, we have shown that the ΔP on day 1 was associated with hospital mortality in with
      pARDS patients.
    

Intervention name(s): driving pressure
Intervention type(s): Device
Intervention description(s): Mechanically ventilated patients (via ETT or trachestomy) were recorded for patients whose ventilation duration lasted at least 24 hours.We divided the patients into two groups by calculating the oxygenation index (OI): [mean airway pressure(MAP) × fraction of inspired oxygen (FiO2) ]/ partial pressure of oxygen in arterial blood (PaO2) × 100) used in the classification of PALICC, including pARDS and non-pARDS.
Observational model: Case-Crossover
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        In our study, patients who received invasive mechanical ventilation support due to
        respiratory failure in the pediatric intensive care unit over 1 month and under 18 years
        were included in the study between March 2018 and April 2020.

        Mechanically ventilated patients (via ETT or trachestomy) were recorded for patients whose
        ventilation duration lasted at least 24 hours. We divided the patients into two groups by
        calculating the oxygenation index (OI): [mean airway pressure(MAP) × fraction of inspired
        oxygen (FiO2) ]/ partial pressure of oxygen in arterial blood (PaO2) × 100) used in the
        classification of PALICC, including ARDS and non-ARDS.
      
Biospecimen description: 
      All patients were ventilated with volume control (VCV) or pressure control (PCV) mode during
      the hospitalization. İn order to measure the driving pressure of patients, Pplat was measured
      in the mechanical ventilator every 12 hours using an inspiratory hold maneuver. The average
      Pplat was calculated using the mean of 2 measurements within 24 hours. Then, the total PEEP
      was measured by expiratory hold maneuver and ΔP was calculated with the Pplat-PEEP formula.
    
Keywords: Driving pressure; mortality; Pediatric intensive care unit; Pediatric acute respiratory distress syndrome