Variation in Positive End-Expiratory Pressure Levels for Mechanically Ventilated Extremely Low Birth Weight Infants

Abstract

Objective: To test the hypothesis that significant positive end-expiratory pressure (PEEP) level variation exists between neonatal centers.

Study design: We performed a secondary analysis cohort study of the Nasal Intermittent Positive-Pressure Ventilation trial. Our study population was extremely low birth weight infants requiring mechanical ventilation within 28 days of life. The exposure was neonatal center; 34 international centers participated in the trial. Subjects from centers with fewer than 5 eligible cases were excluded. The main outcome was the maximal PEEP level used during the first course of mechanical ventilation. Infant characteristics judged a priori to directly influence clinical PEEP level selection and all characteristics associated with PEEP at P <.05 in bivariable analyses were included with and without center in multivariable linear regression models. Variation in PEEP level use between centers following adjustment for infant characteristics was assessed.

Results: A total of 278 extremely low birth weight infants from 17 centers were included. Maximal PEEP ranged from 3 to 9 cm H₂O, mean = 5.7 (SD = 0.9). Significant variation between centers remained despite adjustment for infant characteristics (P < .0001). Further, center alone explained a greater proportion of the PEEP level variation than all infant characteristics combined.

Conclusions: Marked variation in PEEP levels for extremely low birth weight infants exists between neonatal centers. Research providing evidence-based guidance for this important aspect of respiratory care in preterm infants at high risk of lung injury is needed.

Trial registration: ClinicalTrials.gov: NCT00433212.

Keywords: bronchopulmonary dysplasia; infant, premature; respiration, artificial; respiratory distress syndrome, newborn; ventilator-induced lung injury.

Figure 1. Observed Maximal Positive End-Expiratory Pressure (PEEP) Levels Across Neonatal Centers

Plot depicts unadjusted frequency distribution at each center, ordered from lowest (A) to highest (Q) observed PEEP use. Frequency of subjects at each PEEP level depicted by circle size; larger circles represent a greater number of subjects.

Figure 2. Adjusted Positive End-Expiratory Pressure (PEEP) Levels Across Neonatal Centers After Accounting for Differences in Infant Characteristics

Plots depict estimated marginal means and 95% confidence intervals for each center, ordered from lowest (A) to highest (Q) unadjusted maximal PEEP use. Estimated marginal means obtained through adjustment for all infant characteristics included in multivariable analysis. Results are displayed for maximal (panel A) and mean (panel B) PEEP levels.

Figure 3. Predicted Maximal Positive End-Expiratory Pressure (PEEP) Levels Across Neonatal Centers as a Function of Infant Characteristics

Plot depicts mean and 95% confidence intervals for each center, ordered from lowest (A) to highest (Q) unadjusted PEEP use. Predicted values for each subject determined by all infant characteristics included in multivariable analysis. This emphasizes that observed variation in PEEP level use across centers is not a reflection of differences in infant characteristics between centers.

Figure 4. Adjusted Positive End-Expiratory Pressure (PEEP) Levels Across Global Region After Accounting for Differences in Infant Characteristics

Plots depict estimated marginal means and 95% confidence intervals for each global region. Estimated marginal means obtained through adjustment for all infant characteristics in multivariable analysis. Results are displayed for maximal (panel A) and mean (panel B) PEEP levels.