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An In Vitro Study to Assess Determinant Features Associated With Fluid Sealing in the Design of Endotracheal Tube Cuffs and Exerted Tracheal Pressures*

Li Bassi, Gianluigi MD1–3; Ranzani, Otavio Tavares MD1–4; Marti, Joan Daniel RPT1; Giunta, Valeria MD1,5; Luque, Nestor MD1; Isetta, Valentina BSEBE6; Ferrer, Miquel MD, PhD1–3; Farre, Ramon PhD2,3,6; Pimentel, Guilherme Leite BSEBE7; Torres, Antoni MD, PhD1–3,8

doi: 10.1097/CCM.0b013e31826a4804
Laboratory Investigations

Objective: To assess the structural characteristics involved in the design of high-volume low-pressure endotracheal tube cuffs that are associated with fluid sealing effectiveness and to determine the extent of transmitted tracheal pressures upon cuff inflation.

Design: In vitro study.

Settings: Pneumology laboratories.

Interventions: Eight high-volume low-pressure cuffs of cylindrical or tapered shape, made of polyvinylchloride or polyurethane, were studied. Cuffs were tested within a tracheal model, oriented 30° above horizontal to assess 1 hr leakage of oropharyngeal secretions simulant at cuff internal pressures of 15–30 cm H2O. The four best performing cuffs were evaluated for 24 hrs using an internal pressure of 30 cm H2O. The extent of transmitted tracheal wall pressure throughout the cuff–trachea contact area was determined using an internal pressure sensor within a tracheal model upon cuff inflation up to 30 cm H2O.

Measurements and Main Results: Outer diameter, length, and compliance of each cuff were assessed. Multivariate regression analysis was performed to identify the main determinants of simulant leakage rate. The cuff–trachea contact area and the percentage of tracheal wall pressure measurements greater than 50 cm H2O were computed. Cuff design characteristics significantly differ among tubes. The cuffs made of polyurethane showed the best short- and long-term sealing efficacy. Nevertheless, in the multivariate analysis, the cuff outer diameter (n: 288, p = 0.003) and length (n: 288, p < 0.001), along with the internal pressure (n: 288, p < 0.001), were the only predictors of simulant leakage rate. The tapered cuffs showed the lowest tracheal wall contact area (n: 96, p < 0.001). The tracheal wall pressure distribution pattern was heterogeneous, and the percentage of high tracheal wall pressure significantly differs among the cuffs (n: 96, p < 0.001).

Conclusions: The high-volume low-pressure cuffs’ outer diameter, length, material, and internal pressure are the main determinants of sealing efficacy. Despite internal pressure within the safe range, transmitted tracheal pressure is extremely heterogeneous and differs among cuffs, occasionally reaching localized, very high, unsafe levels.

1 Division of Pulmonary and Critical Care, Thorax Institute, Hospital Clinic, Barcelona, Spain.

2 Institut d’Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain.

3 Centro de Investigación Biomedica En Red-Enfermedades Respiratorias, Barcelona, Spain.

4 Respiratory Intensive Care Unit, Pulmonary Division-InCor-Faculdade de Medicina da Universidade de São Paulo, São Paulo, Brazil.

5 Dipartimento Toraco-Polmonare e Cardiocircolatorio, Università degli studi di Milano, IRCCS Fondazione Cà Granda, Milano, Italy

6 Unitat de Biofisica i Bioenginyeria, Facultat de Medicina, Universitat de Barcelona, Barcelona, Spain.

7 Department of Physics, Princeton University, Jadwin Hall, Princeton, NJ.

8 University of Barcelona, Barcelona, Spain

*See also p. 681.

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Drs. Li Bassi and Ranzani equally contributed to this work.

Drs. Li Bassi and Ranzani had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Dr. Li Bassi, Ms. Isetta, Dr. Ferrer, and Dr. Torres contributed to design and study concept; Dr. Bassi, Dr. Ranzani, Mr. Marti, Dr. Luque, and Dr. Giunta helped in acquisition of data; Drs. Li Bassi and Ranzani helped in analysis and interpretation the data, statistical analysis, and drafting of the article; Dr. Li Bassi, Ms. Isetta, Dr. Ferrer, Dr. Farre, Mr. Pimentel, and Dr. Torres helped in critical revision of the article for important intellectual content.

This study was conducted at the laboratories of the University of Barcelona, Spain.

This work was supported by Covidien, Ltd; SEPAR-ALAT fellowship; Institut d’Investigacions Biomèdiques August Pi i Sunyer, and University of Barcelona.

Dr. Li Bassi received honoraria for lectures from Covidien Ltd. Dr. Torres received research grants and honoraria for lectures from Covidien Ltd. The remaining authors have not disclosed any potential conflicts of interest.

For information regarding this article, E-mail: atorres@clinic.ub.es

© 2013 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins