Regional distribution of acoustic-based lung vibration as a function of mechanical ventilation mode

Dellinger, R.P.; Smith, Julian Anderson; Cinel, İsmail; Tay, Christina; Rajanala, Susmita; Glickman, Yael A.; Parrillo, Joseph E.

doi:10.1186/cc5706

Cited by 68 publications

(94 citation statements)

References 22 publications

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“…3) Finally, the inlet pressure (P) was prescribed using a square wave, as seen in the literature for a pressure-limited, constant-flow ventilator. 29 The upper limit of the square wave was the positive inspiratory pressure minus the positive end expiratory pressure, while the lower limit was 1 atm. Each peak of the square wave was exactly 0.416 seconds wide, which was the inspiratory time of the ventilator.…”

Section: Air Flow Analysismentioning

confidence: 99%

Decreased <em>Pseudomonas aeruginosa</em> biofilm formation on nanomodified endotracheal tubes: a dynamic lung model

Machado¹,

Webster²

2016

IJN

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Ventilator-associated pneumonia (VAP) is a serious complication of mechanical ventilation that has been shown to be associated with increased mortality rates and medical costs in the pediatric intensive care unit. Currently, there is no cost-effective solution to the problems posed by VAP. Endotracheal tubes (ETTs) that are resistant to bacterial colonization and that inhibit biofilm formation could provide a novel solution to the problems posed by VAP. The objective of this in vitro study was to evaluate differences in the growth of Pseudomonas aeruginosa on unmodified polyvinyl chloride (PVC) ETTs and on ETTs etched with a fungal lipase, Rhizopus arrhizus , to create nanoscale surface features. These differences were evaluated using an in vitro model of the pediatric airway to simulate a ventilated patient in the pediatric intensive care unit. Each experiment was run for 24 hours and was supported by computational models of the ETT. Dynamic conditions within the ETT had an impact on the location of bacterial growth within the tube. These conditions also quantitatively affected bacterial growth especially within the areas of tube curvature. Most importantly, experiments in the in vitro model revealed a 2.7 log reduction in the number (colony forming units/mL) of P. aeruginosa on the nanoroughened ETTs compared to the untreated PVC ETTs after 24 hours. This reduction in total colony forming units/mL along the x -axis of the tube was similar to previous studies completed for Staphylococcus aureus . Thus, this dynamic study showed that lipase etching can create surface features of nanoscale roughness on PVC ETTs that decrease bacterial attachment of P. aeruginosa without the use of antibiotics and may provide clinicians with an effective and inexpensive tool to combat VAP.

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Section: Air Flow Analysismentioning

confidence: 99%

Decreased <em>Pseudomonas aeruginosa</em> biofilm formation on nanomodified endotracheal tubes: a dynamic lung model

Machado¹,

Webster²

2016

IJN

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“…First, neither VRI nor EIT measure lung volume directly. Based on previous results that showed strong linear correlation of both rel.DZ (EIT) and VEA (VRI) with V T [6,14] for the entire lung, our analysis assumes a linear relationship between regional signal changes from each method, and regional V T . Although there is no theoretical bias for this assumption, this simple relationship does allow scaling of the total change in each signal (rel.DZ for EIT, VEA for VRI) to an externally measured total V T .…”

Section: Discussionmentioning

confidence: 99%

“…It is known that sound energy is affected by both flow through the airways and V T [14,25]; however, only V T was considered in the analysis of the correlation between VEA and amplitudes of rel.DZ. We further limited the analysis to VEA at the peak flow rate of the inspiratory phase.…”

Section: Discussionmentioning

confidence: 99%

“…VRI can be regarded as an ''electronic stethoscope'', which records sounds from the chest using acoustic microphones [9] and converts them into grey-scale images [10,11,12]. Several studies have demonstrated that VRI technology is an excellent way to detect lung sound distribution during mechanical ventilation in both animal models and patients [13,14,15,16]. VRI has not yet been validated against any established methods, such as CT or EIT, in assessing regional ventilation distribution.…”

Section: Introductionmentioning

confidence: 99%

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Assessment of regional ventilation distribution: comparison of vibration response imaging (VRI) with electrical impedance tomography (EIT)

Boehme

Shi

Bentley

et al. 2013

European Journal of Anaesthesiology

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“…For this flow model, the boundary conditions prescribed over the domain were as follows: (1) on the solid wall of the tube a no slip condition was applied; (2) an absolute pressure of 1 atm was assumed at the outlet, as is common within the clinical setting; and (3) finally, the inlet pressure for a pressure-limited, constant flow ventilator was represented using a square wave, as seen in the literature. 33 The upper limit of the square wave was the positive inspiratory pressure minus the positive end-expiratory pressure, whereas the lower limit was 1 atm. Each peak was exactly 0.416 seconds wide, the inspiratory time of the ventilator.…”

Section: Airflow Analysismentioning

confidence: 99%

Decreased Staphylococcus aureus biofilm formation on nanomodified endotracheal tubes: a dynamic airway model

Machado

Tarquinio²,

Webster

2012

IJN

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Ventilator-associated pneumonia (VAP) is a serious and costly clinical problem. Specifically, receiving mechanical ventilation for over 24 hours increases the risk of VAP and is associated with high morbidity, mortality, and medical costs. Cost-effective endotracheal tubes (ETTs) that are resistant to bacterial infections could help prevent this problem. The objective of this study was to determine differences in the growth of Staphylococcus aureus on nanomodified and unmodified polyvinyl chloride (PVC) ETTs under dynamic airway conditions simulating a ventilated patient. PVC ETTs were modified to have nanometer surface features by soaking them in Rhizopus arrhisus, a fungal lipase. Twenty-four-hour experiments (supported by computational models) showed that airflow conditions within the ETT influenced both the location and the concentration of bacterial growth on the ETTs, especially within areas of tube curvature. More importantly, experiments revealed a 1.5 log reduction in the total number of S. aureus on the novel nanomodified ETTs compared with the conventional ETTs after 24 hours of airflow. This dynamic study showed that lipase etching can create nanorough surface features on PVC ETTs that suppress S. aureus growth, and thus may provide clinicians with an effective and inexpensive tool to combat VAP.

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Regional distribution of acoustic-based lung vibration as a function of mechanical ventilation mode

Cited by 68 publications

References 22 publications

Decreased <em>Pseudomonas aeruginosa</em> biofilm formation on nanomodified endotracheal tubes: a dynamic lung model

Decreased <em>Pseudomonas aeruginosa</em> biofilm formation on nanomodified endotracheal tubes: a dynamic lung model

Assessment of regional ventilation distribution: comparison of vibration response imaging (VRI) with electrical impedance tomography (EIT)

Decreased Staphylococcus aureus biofilm formation on nanomodified endotracheal tubes: a dynamic airway model

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