Transpulmonary thermodilution detects rapid and reversible increases in lung water induced by positive end-expiratory pressure in acute respiratory distress syndrome

Abstract

Purpose: It has been suggested that, by recruiting lung regions and enlarging the distribution volume of the cold indicator, increasing the positive end-expiratory pressure (PEEP) may lead to an artefactual overestimation of extravascular lung water (EVLW) by transpulmonary thermodilution (TPTD). Methods:In 60 ARDS patients, we measured EVLW (PiCCO2 device) at a PEEP level set to reach a plateau pressure of 30 cmH 2 O (HighPEEP start ) and 15 and 45 min after decreasing PEEP to 5 cmH 2 O (LowPEEP 15′ and LowPEEP 45′ , respectively). Then, we increased PEEP back to the baseline level (HighPEEP end ). Between HighPEEP start and LowPEEP 15′ , we estimated the degree of lung derecruitment either by measuring changes in the compliance of the respiratory system (Crs) in the whole population, or by measuring the lung derecruited volume in 30 patients. We defined patients with a large derecruitment from the other ones as patients in whom the Crs changes and the measured derecruited volume were larger than the median of these variables observed in the whole population. Results:Reducing PEEP from HighPEEP start (14 ± 2 cmH 2 O) to LowPEEP 15′ significantly decreased EVLW from 20 ± 4 to 18 ± 4 mL/kg, central venous pressure (CVP) from 15 ± 4 to 12 ± 4 mmHg, the arterial oxygen tension over inspired oxygen fraction (PaO 2 /FiO 2 ) ratio from 184 ± 76 to 150 ± 69 mmHg and lung volume by 144 [68-420] mL. The EVLW decrease was similar in "large derecruiters" and the other patients. When PEEP was re-increased to HighPEEP end , CVP, PaO 2 /FiO 2 and EVLW significantly re-increased. At linear mixed effect model, EVLW changes were significantly determined only by changes in PEEP and CVP (p < 0.001 and p = 0.03, respectively, n = 60). When the same analysis was performed by estimating recruitment according to lung volume changes (n = 30), CVP remained significantly associated to the changes in EVLW (p < 0.001). Conclusions:In ARDS patients, changing the PEEP level induced parallel, small and reversible changes in EVLW. These changes were not due to an artefact of the TPTD technique and were likely due to the PEEP-induced changes in CVP, which is the backward pressure of the lung lymphatic drainage.

Lung ultrasound score assessing the pulmonary edema in pediatric acute respiratory distress syndrome received continuous hemofiltration therapy: A prospective observational study

“…In the last decade, a metaanalysis showed that lung ultrasound had a high sensitivity and speci city in critically ill patients who were characterized by pulmonary pathology (20), especially in aspect of assessing EVLW (21,22). The association of EVLW determined by PiCCO 2 with PaO 2 / FiO 2 or OI is affected by BW, height, or PEEP (23)(24)(25)(26). According to previous report, LUS as a convenient, noninvasive and portable technique could detect various pathophysiological changes including lung edema and derecruited lung (9,13,27), and LUS can detect the increased EVLW by the appearance of B-lines in ARDS (28).…”

Lung ultrasound score assessing the pulmonary edema in pediatric acute respiratory distress syndrome received continuous hemofiltration therapy: a prospective observational study

“…In the last decade, a meta-analysis showed that lung ultrasound had a high sensitivity and specificity in critically ill patients who were characterized by pulmonary pathology [ 20 ], especially in aspect of assessing EVLW [ 21 , 22 ]. The association of EVLW determined by PiCCO 2 with PaO 2 / FiO 2 or OI is affected by BW, height, or PEEP [ 23 – 26 ]. According to previous report, LUS as a convenient, noninvasive and portable technique could detect various pathophysiological changes including lung edema and derecruited lung [ 9 , 13 , 27 ], and LUS can detect the increased EVLW by the appearance of B-lines in ARDS [ 28 ].…”

Lung Ultrasound Score Assessing the Pulmonary Edema in Pediatric Acute Respiratory Distress Syndrome Received Continuous Hemofiltration Therapy: A Prospective Observational Study

“…In the last decade, a meta-analysis showed that lung ultrasound had a high sensitivity and speci city in critically ill patients who were characterized by pulmonary pathology (23), especially in aspect of assessing EVLW (24,25). The association of EVLW determined by PiCCO 2 with PaO 2 / FiO 2 or OI is affected by BW, height, or PEEP (5)(6)(7)(8). According to previous report, LUS as a convenient, noninvasive and portable technique could detect various pathophysiological changes including lung edema and derecruited lung (19,20,26), and LUS can detect the increased EVLW by the appearance of B-lines in ARDS (27).…”

“…Monitoring EVLW with pulse indicator continuous cardiac output (PiCCO 2 ) device is available at the bedside for estimating the physiologic correlated to pulmonary edema. However, accumulated evidences demonstrated that an association of EVLW and PaO 2 /FiO 2 or oxygenation index (OI) is affected by body weight (BW), height, or positive end-expiratory pressure (PEEP) (5)(6)(7)(8). Moreover, detection of EVLW by a PiCCO 2 device is invasive and inconvenient.…”