Background: Previous physiological studies have identified factors that are involved in auto-PEEP generation. In our study, we examined how much auto-PEEP is generated from factors that are involved in its development.

Methods: One hundred eighty-six subjects undergoing controlled mechanical ventilation with persistent expiratory flow at the beginning of each inspiration were enrolled in the study. Volume-controlled continuous mandatory ventilation with PEEP of 0 cm H2O was applied while maintaining the ventilator setting as chosen by the attending physician. End-expiratory and end-inspiratory airway occlusion maneuvers were performed to calculate respiratory mechanics, and tidal flow limitation was assessed by a maneuver of manual compression of the abdomen.

Results: The variable with the strongest effect on auto-PEEP was flow limitation, which was associated with an increase of 2.4 cm H2O in auto-PEEP values. Moreover, auto-PEEP values were directly related to resistance of the respiratory system and body mass index and inversely related to expiratory time/time constant. Variables that were associated with the breathing pattern (tidal volume, frequency minute ventilation, and expiratory time) did not show any relationship with auto-PEEP values. The risk of auto-PEEP ≥5 cm H2O was increased by flow limitation (adjusted odds ratio 17; 95% CI: 6-56.2), expiratory time/time constant ratio <1.85 (12.6; 4.7-39.6), respiratory system resistance >15 cm H2O/L s (3; 1.3-6.9), age >65 y (2.8; 1.2-6.5), and body mass index >26 kg/m(2) (2.6; 1.1-6.1).

Conclusions: Flow limitation, expiratory time/time constant, resistance of the respiratory system, and obesity are the most important variables that affect auto-PEEP values. Frequency expiratory time, tidal volume, and minute ventilation were not independently associated with auto-PEEP. Therapeutic strategies aimed at reducing auto-PEEP and its adverse effects should be primarily oriented to the variables that mainly affect auto-PEEP values.

Download full-text PDF

Source
http://dx.doi.org/10.4187/respcare.04063DOI Listing

Publication Analysis

Top Keywords

auto-peep values
20
flow limitation
16
auto-peep
12
expiratory time/time
12
time/time constant
12
factors involved
8
resistance respiratory
8
respiratory system
8
body mass
8
tidal volume
8

Similar Publications

Article Synopsis
  • Dynamic hyperinflation in COPD leads to auto-PEEP, which increases the effort needed for breathing; Automatic tube compensation (ATC) aims to alleviate this.
  • In a study with 60 patients, results showed that activating ATC led to a significant decrease in auto-PEEP across all times of day, with greater reductions observed in stable COPD patients compared to those experiencing exacerbations.
  • Overall, while ATC activation benefits chronic COPD patients by reducing auto-PEEP, those with exacerbations showed less improvement.
View Article and Find Full Text PDF
Article Synopsis
  • The study aimed to evaluate how common elevated mechanical power (MP) values are in critically ill patients on invasive mechanical ventilation.
  • It analyzed data from 372 patients across 133 Critical Care Units, revealing higher MP in pressure-controlled (PC) ventilation compared to volume-controlled (VC) ventilation, but no significant difference in the prevalence of high MP (>17J/min) between the two methods.
  • The findings suggest a notable number of patients may face the risk of high MP, indicating a need for careful monitoring in ventilated patients, despite the lack of a significant difference in high MP prevalence based on the ventilation type.
View Article and Find Full Text PDF

Background: The effect of inverse inspiration:expiration (I:E) ratio on functional residual capacity (FRC) during pneumoperitoneum is unclear. We hypothesised that volume-targeted pressure-controlled inverse ratio ventilation (vtPC-IRV) would increase FRC by increasing the level of auto-PEEP in low respiratory compliance situations.

Methods: During robot-assisted laparoscopic radical prostatectomy, 20 obese patients were sequentially ventilated with four different settings for 30 min in each setting: (1) control, I:E ratio of 1:2 and baseline airway pressure (BAP) of 5 cm HO; (2) IRV2, I:E ratio of 2:1 and BAP off; (3) IRV3, I:E ratio of 3:1 and BAP off; and (4) IRV4, I:E ratio of 4:1 and BAP off.

View Article and Find Full Text PDF

Objectives: To describe pulmonary resistance in children undergoing invasive mechanical ventilation (MV) for different causes.

Design: A cross-sectional study.

Setting: Two PICUs in the South region of Brazil.

View Article and Find Full Text PDF

Background: The ventilatory mechanics of patients with COPD and obesity-hypoventilation syndrome (OHS) are changed when there is air trapping and auto-PEEP, which increase respiratory effort. P measures the ventilatory drive and, indirectly, respiratory effort. The aim of the study was to measure P in subjects with COPD or OHS on treatment with positive pressure and to analyze their changes in P after treatment.

View Article and Find Full Text PDF

Want AI Summaries of new PubMed Abstracts delivered to your In-box?

Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!