Computed Tomography Assessment of Positive End-expiratory Pressure-induced Alveolar Recruitment  in Patients with Acute Respiratory Distress Syndrome

Malbouisson, Luíz Marcelo Sá; Muller, Jean-Charles; Constantin, Jean-Michel; Lü, Qin; Puybasset, Louis; Rouby, Jean‐Jacques

doi:10.1164/ajrccm.163.6.2005001

Cited by 281 publications

(232 citation statements)

References 19 publications

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“…Again, this physiological dynamic has been observed in several clinical studies [e.g. 32,8,22,9,33].…”

Section: Model Validationsupporting

confidence: 55%

“…This result suggests that recruitment and derecruitment is the dominant cause of volume change, rather than isotropic "balloon like", expansion of alveoli as had been traditionally thought, which is discussed in [16]. This elastic expansion hypothesis is also utilized by a variety of other clinical studies [18,19,20,8,13,14,21,22,9,23,24,25,26], and is in contrast to the in-vivo and clincally observed, more discrete open-closed behaviour employed here.…”

Section: A Lung Unitsupporting

confidence: 44%

“…The results of this model show that as PEEP increases, the TOP distribution mean decreases, while the TCP distribution mean increases. These shifts indicate the change in recruitment and derecruitment characteristics of lung units as PEEP is altered [8,22,9]. The model requires a minimum of two PV loops at different PEEP settings to obtain all the required parameters.…”

Section: Peep[cmhmentioning

confidence: 99%

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A minimal model of lung mechanics and model-based markers for optimizing ventilator treatment in ARDS patients

Sundaresan

Yuta

Hann

et al. 2009

Computer Methods and Programs in Biomedicine

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A majority of patients admitted to the Intensive Care Unit (ICU) require some form of respiratory support. In the case of Acute Respiratory Distress Syndrome (ARDS), the patient often requires full intervention from a mechanical ventilator. ARDS is also associated with mortality rate as high as 70%. Despite many recent studies on ventilator treatment of the disease, there are no well established methods to determine the optimal Positive End Expiratory Pressure (PEEP) or other critical ventilator settings for individual patients. A model of fundamental lung mechanics is developed based on capturing the recruitment status of lung units. The main objective of this research is the simplest possible model that is clinically effective in determining PEEP. The model was identified for a variety of different ventilator settings using clinical data. The fitting error was between 0.1% to 4% over the inflation limb and between 0.3% to 13% over the deflation limb at different PEEP settings. The model produces good correlation with clinical data, and is clinically applicable due to the minimal number of patient specific parameters to identify. The ability to use this identified patient specific model to optimize ventilator management is demonstrated by its ability to predict the patient specific response of PEEP changes before clinically applying them. Predictions of recruited lung volume change with change in PEEP have a median absolute error of 1.87% (IQR:0.93-4.80%; 90% CI:0.16-11.98%) for inflation and a median of 5.76% (IQR:2.71-10.50%; 90% CI:0.43-17.04%) for deflation, across all data sets and PEEP values (N = 34 predictions). This minimal model thus provides a clinically useful and simple platform for continuous patient specific monitoring of lung unit recruitment for a patient.

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“…Again, this physiological dynamic has been observed in several clinical studies [e.g. 32,8,22,9,33].…”

Section: Model Validationsupporting

confidence: 55%

Section: A Lung Unitsupporting

confidence: 44%

Section: Peep[cmhmentioning

confidence: 99%

See 1 more Smart Citation

A minimal model of lung mechanics and model-based markers for optimizing ventilator treatment in ARDS patients

Sundaresan

Yuta

Hann

et al. 2009

Computer Methods and Programs in Biomedicine

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“…Salutary effects on recruitment are supported by CT regional aeration. If the combined change in poorly and non-aerated regional tissue weight relative to total weight is taken as an index of effective recruitment (modified from Malbouisson et al), 17 then recruitment with four hours of ventilation with BVV was 13% (5%) vs -0.3% (7%) with CMV (F = 4.1; P = 0.001 by unpaired Student's t-test). This modest recruitment effect translated into a 24% increase in normally aerated gas volume, suggesting significant restoration of effective gas exchanging units with BVV, similar to previous reports.…”

Section: Discussionmentioning

confidence: 99%

Resolution of pulmonary edema with variable mechanical ventilation in a porcine model of acute lung injury

Graham

Gulati

Kha

et al. 2011

Can J Anesth/J Can Anesth

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Objective Resolution of the acute respiratory distress syndrome (ARDS) requires clearance of pulmonary edema. Biologically variable ventilation (BVV) strategies that improve gas exchange, lung mechanics, and inflammatory mediators in ARDS may be beneficial in this regard. We used quantitative computed tomography (CT), a single indicator thermodilution system (PiCCOÒ) to determine extravascular lung water (EVLW), and the change in edema protein concentration over time to compare edema clearance with BVV vs conventional mechanical ventilation (CMV) in a porcine ARDS model. Methods Sixteen pigs with oleic acid lung injury were randomized to four hours of ventilation with either CMV (n = 8) or BVV (n = 8) at identical low tidal volume and minute ventilation over time. Hemodynamic variables, gas exchange, lung mechanics, and PiCCO derived EVLW were determined hourly. Computed tomography images and edema fluid samples were obtained at baseline lung injury and after four hours of ventilation. Wet and dry lung weights were determined postmortem.Results At four hours with BVV, peak airway pressure was decreased significantly and lung compliance improved compared with CMV (P = 0.003; P \ 0.001, respectively). Hemodynamic variables and gas exchange were not different between groups. Also at four hours, computed tomography revealed an increase in total gas volume (P = 0.001) and a decrease in total lung weight and global lung density (P = 0.005; P = 0.04 respectively) with BVV. These findings were associated with a significant increase in the gas volume of normally aerated lung regions (P \ 0.001) and a decrease in the poorly and non-aerated lung regions (P = 0.001). No change in any CT parameter occurred with CMV. The lung weights derived from computed tomography correlated well with postmortem wet weights (R 2 = 0.79; P \ 0.01). The decrease in PiCCO derived EVLW from injury to four hours did not differ significantly between BVV and CMV. Extravascular lung water showed no correlation with postmortem wet weights and significantly underestimated lung water. Average alveolar fluid clearance rates were positive (1.4%Áhr -1 (3%)) with BVV and negative with CMV (-2.0%Áhr -1 (4%)). Conclusions In a comparison between BVV and CMV, computed tomography evidence suggests that BVV facilitates enhanced clearance and/or redistribution of edema fluid with improved recruitment of atelectatic and poorly aerated lung regions; no such evidence was seen with either single thermodilution measurement of EVLW or edema clearance rates. The results of computed tomography provide further evidence of the benefit of BVV over conventional ventilation in ARDS. RésuméObjectif La re´solution d'un syndrome de de´tresse respiratoire aigue¨(SDRA) ne´cessite l'e´limination de

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“…Os principais fatores que podem contribuir para a formação de atelectasias nessa situação são: reação inflamatória da circulação extracorpórea 3,23 , hipotermia, esternotomia, manipulação das cavidades pleurais, uso de bloqueadores neuromusculares e ventilação com altas frações de oxigênio inspiradas durante o período intraoperatório. O peso do coração também tem papel preponderante na formação de atelectasias, conforme demonstrado em investigação conduzida por Malbouisson e col. 24 . Observou-se no presente estudo que a oxigenação aumentou de forma simultânea com elevação do volume corrente exalado, demonstrando que o recrutamento de alvéolos 13 e Michalopoulos e col. 14 , estudando os efeitos da PEEP na oxigenação de pacientes após intervenção cirúrgica cardíaca, demonstraram que valores inferiores a 10 cmH 2 O não são efetivos para abrir unidades alveolares colapsadas.…”

Section: Discussionunclassified

Manobra de recrutamento alveolar na reversão da hipoxemia no pós-operatório imediato em cirurgia cardíaca

Auler¹,

Nozawa²,

Toma³

et al. 2007

Rev. Bras. Anestesiol.

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Computed Tomography Assessment of Positive End-expiratory Pressure-induced Alveolar Recruitment in Patients with Acute Respiratory Distress Syndrome

Cited by 281 publications

References 19 publications

A minimal model of lung mechanics and model-based markers for optimizing ventilator treatment in ARDS patients

A minimal model of lung mechanics and model-based markers for optimizing ventilator treatment in ARDS patients

Resolution of pulmonary edema with variable mechanical ventilation in a porcine model of acute lung injury

Manobra de recrutamento alveolar na reversão da hipoxemia no pós-operatório imediato em cirurgia cardíaca

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