Evaluation of Recruited Lung Volume at Inspiratory Plateau Pressure With PEEP Using Bedside Digital Chest X-ray in Patients With Acute Lung Injury/ARDS

Abstract

BACKGROUND:We wanted to assess whether there was a significant relationship between recruited lung volume (V rec ) and change in density on digital processed chest x-ray measured at 2 different levels of inspiratory plateau pressure corresponding to 2 PEEP levels in patients with acute lung injury or ARDS. METHODS: In 14 subjects, PEEP 5 cm H 2 O and 15 cm H 2 O were prospectively applied in a random order for 10 min. At the end of each period, chest x-ray was taken using a digital portable device, and a pressure-volume curve of the respiratory system was performed. We also assessed P aO 2 , and the static and the dynamic (C dyn,rs ) compliance of the respiratory system. Change in end-expiratory lung volume between tidal breath and relaxation volume of the respiratory system was determined. Radiological attenuation was measured on chest x-rays in 4 regions of interest in the right lung, and in 3 regions of interest in the left lung, drawn in posterior intercostal spaces from top to bottom, by using dedicated software. The ratio of lung density in each region between PEEP 15 and PEEP 5 (rP15/P5) and their arithmetic mean (P15/P5) were computed. V rec was determined from the pressure-volume curves. RESULTS: The median value of rP15/P5 in the 98 lung levels was 0.91 (0.80 -1.01), which was significantly different from 1 (P < .001). The values of rP15/P5 were not significantly different between the lung levels. The median values of V rec and P15/P5 were 288 (173-402) mL and 0.90 (0.80 -0.97), respectively. There was a significant negative correlation between V rec and P15/P5 (R ‫؍‬ ؊0.77, P ‫؍‬ .01). The reduction in P15/P5 tended to correlate with the increase in C dyn,rs (R ‫؍‬ ؊0.49, P ‫؍‬ .077) or in P aO 2 (R ‫؍‬ ؊0.53, P ‫؍‬ .05) between PEEP 15 cm H 2 O and PEEP 5 cm H 2 O. CONCLUSIONS: Digital chest x-ray done at the bedside in acute lung injury/ARDS subjects was able to detect a reduction in density between PEEP 5 cm H 2 O and PEEP 15 cm H 2 O, which correlated with V rec .

Recruitment Maneuvers and PEEP Titration

“…Digital chest radiography done at the bedside with PEEP of 5 and 15 cm H 2 O might also be useful to detect recruited lung volume. 92 Ultrasound uses an emission frequency of 5-7 MHz for visualization of the lung. The probe should have a small convex tip that can be easily placed on intercostal spaces to allow an acoustic window on the parenchyma.…”

Measurement of Alveolar Recruitment at the Bedside: The Beginning of a New Era in Respiratory Monitoring?

“…1 The reference method for the comparison was the pressure-volume (PV) curve method, one of the methods commercially available at the bedside for measuring PEEP-induced alveolar recruitment. This original finding renews the place of bedside chest radiographies that are routinely performed in critically ill patients with ARDS: they could serve not only as a qualitative tool for assessing lung aeration but also as a monitoring tool for quantifying alveolar recruitment.…”

Wpływ jednostronnego PEEP na biomechanikę obu płuc podczas niezależnej wentylacji u chorych znieczulanych do zabiegów torakochirurgicznych

“…According to recent studies, the use of a PEEP at even 5 cm H 2 O increases compliance by 20%; the PEEP recommended by Wallet and co-workers in patients with ARDS is 15 cm H 2 O [18]. In cases of pulmonary pathology with coexisting intra-abdominal hypertension, the beneficial effects of PEEP are observed, irrespective of the method of PEEP application [19].…”