Document Detail


The pressure-volume curve is greatly modified by recruitment. A mathematical model of ARDS lungs.
MedLine Citation:
PMID:  9655729     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
A mathematical model of the ARDS lung, with simulated gravitational superimposed pressure, evaluated the effect of varying alveolar threshold opening pressures (TOP), PEEP and peak inspiratory pressure (PIP) on the static pressure-volume (PV) curve. The lower inflection point (Pflex) was affected by SP and TOP, and did not accurately indicate PEEP required to prevent end-expiratory collapse. Reinflation of collapsed lung units (recruitment) continued on the linear portion of the PV curve, which had a slope at any volume greater than the total compliance of aerated alveoli. As recruitment diminished, the reduced PV slope could produce an upper Pflex at 20 to 30 cm H2O pressure. An upper Pflex caused by alveolar overdistension could be modified or eliminated by recruitment with high TOP. With constant PIP as PEEP increased, and TOP range of 5 to 60 cm H2O, PEEP to prevent end-expiratory collapse was indicated by minimum PV slope above 20 cm H2O, minimum hysteresis, and maximum volume at a pressure of 20 cm H2O. With constant inflation volume as PEEP increased, the effect on PV slope was unpredictable. Although increased PV slope indicated recruitment, maximum PV slope usually underestimated PEEP required to prevent end-expiratory collapse. Therefore, with this model the PV curve did not reliably predict optimal ventilator settings.
Authors:
K G Hickling
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  American journal of respiratory and critical care medicine     Volume:  158     ISSN:  1073-449X     ISO Abbreviation:  Am. J. Respir. Crit. Care Med.     Publication Date:  1998 Jul 
Date Detail:
Created Date:  1998-07-30     Completed Date:  1998-07-30     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  9421642     Medline TA:  Am J Respir Crit Care Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  194-202     Citation Subset:  AIM; IM    
Affiliation:
Intensive Care Unit and Department of Anaesthesia, Queen Elizabeth Hospital, Kowloon; and Department of Anesthesia and Intensive Care, Chinese University of Hong Kong, Hong Kong.
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MeSH Terms
Descriptor/Qualifier:
Humans
Lung / physiopathology*
Lung Compliance
Models, Theoretical*
Positive-Pressure Respiration
Pressure
Pulmonary Alveoli / physiopathology
Respiratory Distress Syndrome, Adult / physiopathology*

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