Role of absolute lung volume to assess alveolar recruitment in acute respiratory distress syndrome patients

Patroniti, Nicolò; Bellani, Giacomo; Cortinovis, Barbara; Maggioni, Elena; Manfio, A; Pesenti, Antonio

doi:10.1097/ccm.0b013e3181d8cb51

Cited by 35 publications

(25 citation statements)

References 42 publications

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“…As for plateau pressure, this relationship could be demonstrated for the entire lung and, even more strongly, for the normally aerated tissue, suggesting that the smaller the ''baby lung'' receiving the tidal inflation, the more this will promote inflammation. This finding has potential clinical relevance because it supports the evidence (45,46) that, to set the appropriate VT, end-expiratory lung volume should be taken into account. In this study we used CT to measure end-expiratory lung volumes, whose measurements are in tight agreement with those obtained by bedside methods (15,47).…”

Section: Discussionsupporting

confidence: 67%

Lung Regional Metabolic Activity and Gas Volume Changes Induced by Tidal Ventilation in Patients with Acute Lung Injury

Bellani¹,

Guerra²,

Musch³

et al. 2011

Am J Respir Crit Care Med

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190

159

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Rationale: During acute lung injury (ALI), mechanical ventilation can aggravate inflammation by promoting alveolar distension and cyclic recruitment-derecruitment. As an estimate of the intensity of inflammation, metabolic activity can be measured by positron emission tomography imaging of [ 18 F]fluoro-2-deoxy-D-glucose. Objectives: To assess the relationship between gas volume changes induced by tidal ventilation and pulmonary metabolic activity in patients with ALI. Methods: In 13 mechanically ventilated patients with ALI and relatively high positive end-expiratory pressure, we performed a positron emission tomography scan of the chest and three computed tomography scans: at mean airway pressure, end-expiration, and end-inspiration. Metabolic activity was measured from the [ 18 F]fluoro-2-deoxy-D-glucose uptake rate. The computed tomography scans were used to classify lung regions as derecruited throughout the respiratory cycle, undergoing recruitment-derecruitment, and normally aerated. Measurements and Main Results: Metabolic activity of normally aerated lung was positively correlated both with plateau pressure, showing a pronounced increase above 26 to 27 cm H 2 O, and with regional VT normalized by end-expiratory lung gas volume. This relationship did not appear to be caused by a higher underlying parenchymal metabolic activity in patients with higher plateau pressure. Regions undergoing cyclic recruitment-derecruitment did not have higher metabolic activity than those collapsed throughout the respiratory cycle. Conclusions: In patients with ALI managed with relatively high endexpiratory pressure, metabolic activity of aerated regions was associated with both plateau pressure and regional VT normalized by end-expiratory lung gas volume, whereas no association was found between cyclic recruitment-derecruitment and increased metabolic activity.Keywords: acute lung injury; respiration, artificial; tomography, X-ray computed; positron emission tomographyWe reported (1) that positron emission tomography (PET) with [ 18 F]fluoro-2-deoxy-D-glucose ( 18 FDG) shows diffuse increase in metabolic activity in the lungs of patients with acute lung injury (ALI) and acute respiratory distress syndrome (ARDS).In keeping with previous evidence, we interpreted the increased metabolic activity as indicating the presence of an inflammatory process (2-5). The cross-registration of dynamic PET images with computed tomography (CT) scans allowed us to show that the increased metabolic activity was not confined to regions with abnormal density but also involved normally aerated regions (1, 6).Mechanical ventilation can be a powerful inflammatory stimulus and ventilator-induced lung injury (VILI) has been the object of extensive research. Two main mechanisms have been advocated for VILI, the first being the cyclic recruitment and derecruitment of alveolar units (sometimes referred to as ''atelectrauma'') (7, 8) and the second being the (over)distension of aerated alveolar units (9, 10). Most of the data on VILI derive from animal ...

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Section: Discussionsupporting

confidence: 67%

Lung Regional Metabolic Activity and Gas Volume Changes Induced by Tidal Ventilation in Patients with Acute Lung Injury

Bellani¹,

Guerra²,

Musch³

et al. 2011

Am J Respir Crit Care Med

Self Cite

190

159

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“…However, we must point out that the physiologic method used in the current study to estimate alveolar recruitment 36,37 has been shown to underestimate alveolar recruitment in some instances (see below for the limitations). 43 Interestingly, we document that the open lung strategy decreased E CW . To explain this result, we speculate that PEEP, applied after the RM, at least partially counterbalanced the diaphragm cranial shift induced by pneumoperitoneum and Trendelenburg position and that the corresponding lung expansion lead to a more physiologic chest wall shape leading to the observed reduction in E CW .…”

Section: Discussionmentioning

confidence: 94%

“…Although our data show that such strategy resulted in significant alveolar recruitment and improvement in lung mechanics, we must point out that the PEEP level applied in our study was likely inadequate to maximize alveolar recruitment. As we discussed above, tailoring PEEP to optimize alveolar recruitment is an important issue that deserves further studies; (5) to estimate open lung strategy-induced alveolar recruitment, we used the method originally proposed by Ranieri et al 36 We point out that although this method is useful to indicate that recruitment occurred, it may fail to precisely estimate the amount of alveolar recruitment in some instances, as recently shown by Patroniti et al 43 We acknowledge this as a limitation of our study; and (6) the FloTrac/Vigileo has not been thoroughly validated in the surgical context and furthermore is validated to monitor the trend of cardiac output rather than its absolute values. 33,44 In conclusion, we document the physiologic effects of a ventilatory strategy aiming at reversing pneumoperitoneuminduced alveolar collapse in patients with normal lung function undergoing laparoscopic surgery in Trendelenburg position.…”

Section: Discussionmentioning

confidence: 99%

Effects of Recruitment Maneuver and Positive End-expiratory Pressure on Respiratory Mechanics and Transpulmonary Pressure during Laparoscopic Surgery

et al. 2013

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Background: The authors tested the hypothesis that during laparoscopic surgery, Trendelenburg position and pneumoperitoneum may worsen chest wall elastance, concomitantly decreasing transpulmonary pressure, and that a protective ventilator strategy applied after pneumoperitoneum induction, by increasing transpulmonary pressure, would result in alveolar recruitment and improvement in respiratory mechanics and gas exchange. Methods: In 29 consecutive patients, a recruiting maneuver followed by positive end-expiratory pressure 5 cm H 2 O maintained until the end of surgery was applied after pneumoperitoneum induction. Respiratory mechanics, gas exchange, blood pressure, and cardiac index were measured before (T BSL ) and after pneumoperitoneum with zero positive end-expiratory pressure (T preOLS ), after recruitment with positive end-expiratory pressure (T postOLS ), and after peritoneum desufflation with positive end-expiratory pressure (T end ). Results: Esophageal pressure was used for partitioning respiratory mechanics between lung and chest wall (data are mean ± SD): on T preOLS , chest wall elastance (E cw ) and elastance of the lung (E L ) increased (8.2 ± 0.9 vs. 6.2 ± 1.2 cm H 2 O/L, respectively, on T BSL ; P = 0.00016; and 11.69 ± 1.68 vs. 9.61 ± 1.52 cm H 2 O/L on T BSL ; P = 0.0007). On T postOLS , both chest wall elastance and E L decreased (5.2 ± 1.2 and 8.62 ± 1.03 cm H 2 O/L, respectively; P = 0.00015 vs. T preOLS ), and PaO 2 /inspiratory oxygen fraction improved (491 ± 107 vs. 425 ± 97 on T preOLS; P = 0.008) remaining stable thereafter. Recruited volume (the difference in lung volume for the same static airway pressure) was 194 ± 80 ml. Pplat RS remained stable while inspiratory transpulmonary pressure increased (11.65 + 1.37 cm H 2 O vs. 9.21 + 2.03 on T preOLS ; P = 0.007). All respiratory mechanics parameters remained stable after abdominal desufflation. Hemodynamic parameters remained stable throughout the study. Conclusions:In patients submitted to laparoscopic surgery in Trendelenburg position, an open lung strategy applied after pneumoperitoneum induction increased transpulmonary pressure and led to alveolar recruitment and improvement of E cw and gas exchange. LAPAROSCOPY is a well-established procedure for pelvic gynecologic surgery often performed in Trendelenburg position.1,2 To facilitate laparoscopic surgical manipulation, a pneumoperitoneum is usually induced through carbon dioxide inflation. Both the increase in abdominal pressure as a result of carbon dioxide inflation and the head down body position have been shown to impair the respiratory function during the procedure, mainly inducing atelectasis formation in the dependent lung regions. 1,[3][4][5][6] The resulting decrease in functional residual capacity poses Address correspondence to Dr. Cinnella: Departmentt of Anesthesia and Intensive Care, Policlinico 'Riuniti' -University of Foggia, Viale Pinto 1 -71100 Foggia, Italy. g.cinnella@unifg.it. Information on purchasing reprints may be found at www.anesthesiology.org...

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“…From a technical standpoint, Patroniti et al [30] suggested that the method used to estimate the PEEP volume above FRC with PEEP (long exhalation to ZEEP) may underestimate recruitment because the true FRC may be modified after the use of high PEEP. Therefore, our method might have slightly underestimated recruitment.…”

Section: Discussionmentioning

confidence: 99%

PEEP-induced changes in lung volume in acute respiratory distress syndrome. Two methods to estimate alveolar recruitment

Dellamonica¹,

Lerolle²,

Sargentini³

et al. 2011

Intensive Care Med

137

128

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Role of absolute lung volume to assess alveolar recruitment in acute respiratory distress syndrome patients

Abstract: Functional residual capacity is affected by PEEP. Ignoring this effect leads to relevant underestimation of alveolar recruitment as measure by pressure-volume curve displacement.

Cited by 35 publications

References 42 publications

Lung Regional Metabolic Activity and Gas Volume Changes Induced by Tidal Ventilation in Patients with Acute Lung Injury

Lung Regional Metabolic Activity and Gas Volume Changes Induced by Tidal Ventilation in Patients with Acute Lung Injury

Effects of Recruitment Maneuver and Positive End-expiratory Pressure on Respiratory Mechanics and Transpulmonary Pressure during Laparoscopic Surgery

PEEP-induced changes in lung volume in acute respiratory distress syndrome. Two methods to estimate alveolar recruitment

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