Document Detail

Resistance of pediatric and neonatal endotracheal tubes: influence of flow rate, size, and shape.
MedLine Citation:
PMID:  10834718     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: The aim of this study was to determine the resistances of endotracheal tubes (ETTs) commonly used in neonatal and pediatric intensive care units and the relationship of resistance to flow rate, size, and shape of ETT. SETTING: Laboratory-based measurements. EVALUATION: We examined straight tubes with inner diameters between 2.5 and 6 mm and shouldered (Cole) tubes with inner diameter/outer diameter between 2.5/4 and 3.5/5 mm. We assessed ETT resistance at standard and "appropriate for patient use" lengths at flow rates from 0 L/min to 30 L/min. We used calibrated rotameters to control the flow of gas and proximal static pressure measured by using either an industrial draft gauge or a differential pressure transducer. The ETT resistance was calculated by dividing the proximal ETT pressure by the measured flow and expressed as the mean of three measurements at each flow rate. MAIN RESULTS: Resistance increased as ETT diameter decreased; at flows of 5 L/min and 10 L/min, the resistances of the 6 mm inner diameter ETT were 3.1 H2O/L/sec and 4.6 cm H20/L/ sec, respectively, and the resistances of the 2.5 mm inner diameter ETT were 81.2 H2O/L/sec and 139.4 cm H20/L/sec, respectively. Shortening an ETT to a length appropriate for patient use (e.g., a 4.0 mm inner diameter, from 20.7 to 11.3 cm) reduced its resistance on average by 22%. The resistance of a Cole tube was approximately 50% lower than that of a straight tube with an inner diameter corresponding to the narrow part of the shouldered tube. CONCLUSIONS: Our results suggest that the use of a small-diameter, straight ETT will significantly increase the work of breathing.
T Manczur; A Greenough; G P Nicholson; G F Rafferty
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Critical care medicine     Volume:  28     ISSN:  0090-3493     ISO Abbreviation:  Crit. Care Med.     Publication Date:  2000 May 
Date Detail:
Created Date:  2000-06-08     Completed Date:  2000-06-08     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0355501     Medline TA:  Crit Care Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1595-8     Citation Subset:  AIM; IM    
Department of Child Health, King's College School of Medicine and Dentistry, London, UK.
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MeSH Terms
Airway Resistance*
Equipment Design
Infant, Newborn
Intensive Care Units, Neonatal*
Intubation, Intratracheal / instrumentation*
Pulmonary Ventilation*
Respiratory Mechanics
Transducers, Pressure

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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