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Optimal positive end-expiratory pressure therapy in infants and children with acute respiratory failure
M K White1, S A Galli, R L Chatburn
1Divisions of Pediatric Pharmacology, Rainbow Babies & Childrens Hospital, Cleveland, Ohio 44106.
Insights
Positive end-expiratory pressure (PEEP) improves oxygen but can reduce cardiac output. This study found that neither oxygen levels nor respiratory compliance predicted optimal PEEP for maximal oxygen transport in children with acute respiratory failure.
Area of Science:
- Pediatric Critical Care Medicine
- Respiratory Physiology
- Mechanical Ventilation
Background:
- Positive end-expiratory pressure (PEEP) is crucial for treating hypoxemic acute respiratory failure (ARF).
- While PEEP enhances arterial oxygen tension by reducing intrapulmonary shunting, it may compromise cardiac output and systemic oxygen transport.
- Optimizing oxygen transport is a key therapeutic goal in ARF.
Purpose of the Study:
- To investigate if respiratory system compliance (Crs) or arterial oxygen tension (PaO2) can predict the PEEP level that maximizes oxygen transport in pediatric ARF.
- To evaluate the cardiorespiratory effects of varying PEEP levels in mechanically ventilated children with ARF.
Main Methods:
- Studied 15 children with ARF requiring mechanical ventilation.
- Measured static Crs, PaO2, blood pressures, cardiac index (CI), and oxygen transport at PEEP levels from 0 to 15 cm H2O.
- Analyzed the relationship between PEEP, Crs, PaO2, CI, and oxygen transport.
Main Results:
- PaO2 significantly increased at PEEP ≥ 9 cm H2O.
- Cardiac index (CI) decreased by 15% from 0 to 15 cm H2O PEEP.
- Crs and oxygen transport did not significantly change with increasing PEEP.
- Maximal oxygen transport occurred at the PEEP level associated with the best CI.
- Above the optimal PEEP, CI and oxygen transport decreased significantly while PaO2 continued to rise.
Conclusions:
- Neither PaO2 nor Crs reliably predicted the PEEP level for maximal oxygen transport in normovolemic pediatric ARF patients.
- Optimal PEEP for oxygen transport appears to be linked to the PEEP level that yields the best cardiac index.
- Higher PEEP levels can decrease oxygen transport despite improving PaO2.
Abstract:
Positive end-expiratory pressure (PEEP) has become a mainstay in the treatment of hypoxemic acute respiratory failure (ARF). Whereas PEEP improves arterial oxygen tension by decreasing intrapulmonary shunting, it may also impair cardiac output and hence decrease systemic oxygen transport. Inasmuch as optimizing oxygen transport is a goal of therapy in ARF, we sought to determine if the level of PEEP that results in maximal oxygen transport could be estimated from measurements of compliance of the respiratory system (Crs) or PaO2. We studied the effects of PEEP application on cardiorespiratory parameters in 15 children who required mechanical ventilation for ARF. Static Crs, PaO2, central venous and arterial blood pressures, indicator dilution cardiac index (CI), and oxygen transport were determined at 0, 3, 6, 9, 12, and 15 cm H2O PEEP. PaO2 increased significantly at PEEP levels greater than or equal to 9 cm H2O (p less than 0.001), while CI fell by 15% between 0 and 15 cm end-expiratory pressure (p less than 0.02). Crs and oxygen transport did not change significantly with increasing levels of PEEP. The level of PEEP resulting in maximal oxygen transport ranged from 0 to 15 cm H2O, and in all patients it corresponded to PEEP of best CI. At levels of PEEP above that associated with maximal oxygen transport, CI and oxygen transport fell significantly, while PaO2 continued to rise. No relationship between Crs and oxygen transport was observed. In our normovolemic patients with ARF, neither PaO2 nor Crs predicted PEEP of maximal oxygen transport.(ABSTRACT TRUNCATED AT 250 WORDS)