Document Detail

Conventional ventilation modes with small pressure amplitudes and high positive end-expiratory pressure levels optimize surfactant therapy.
MedLine Citation:
PMID:  10628617     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: High-frequency oscillation studies have shown that ventilation at high end-expiratory lung volumes combined with small volume cycles at high rates best preserves exogenous surfactant and gas exchange in lavaged lungs. We investigated whether surfactant composition and gas exchange can also be preserved by conventional modes of mechanical ventilation, which combine high levels of positive end-expiratory pressure (PEEP) with small pressure amplitudes. DESIGN: Prospective, randomized, nonblinded, controlled study. SETTING: Research laboratory. SUBJECTS: Thirty male Sprague-Dawley rats. INTERVENTIONS: Rats were lung-lavaged and treated with exogenous surfactant (100 mg/kg). After 5 mins, four different ventilator settings (F(IO)2 = 1.0) were applied for 3 hrs in four groups of rats [peak inspiratory pressure (cm H2O); static PEEP (cm H2O); inspiratory/expiratory ratio; frequency], as follows: 26/2/1:2/30 (group 26/2), 26/6/1:2/30 (group 26/6), 20/10/1:2/30 (group 20/ 10-static), and 20/6/7:3/130, creating an auto PEEP of 4 cm H2O (group 20/10-auto). MEASUREMENTS AND MAIN RESULTS: In all groups, Pao2 increased immediately to prelavage values after surfactant therapy. In group 26/2, Pao2 deteriorated to postlavage values within 30 mins when PEEP was decreased to 2 cm H2O, whereas Pao2 remained stable for 3 hrs in the other groups. The Paco2 increased in groups 26/2 and 20/10-static; Paco2 could not be reduced by increasing ventilation frequency to 130 in group 20/10-static. Groups 26/6 and 20/10-auto remained normocapnic. Bronchoalveolar lavage protein concentration was higher in groups 26/2 and 26/6 compared with groups 20/10-static and 20/10-auto. There was significantly more conversion of surface active large aggregates into nonactive small aggregates in group 26/2 compared with groups 20/10-static and 20/10-auto. CONCLUSIONS: We conclude that exogenous surfactant composition is preserved by conventional modes of mechanical ventilation that use small pressure amplitudes, and adequate oxygenation is maintained by high end-expiratory pressure levels. Effective carbon dioxide removal can be achieved by applying a ventilation mode that creates auto PEEP and not by a mode that applies the same level of PEEP by static PEEP only.
S J Verbrugge; D Gommers; B Lachmann
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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:  27     ISSN:  0090-3493     ISO Abbreviation:  Crit. Care Med.     Publication Date:  1999 Dec 
Date Detail:
Created Date:  2000-01-27     Completed Date:  2000-01-27     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:  2724-8     Citation Subset:  AIM; IM    
Department of Anesthesiology, Erasmus University Rotterdam, The Netherlands.
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MeSH Terms
Positive-Pressure Respiration / methods*
Positive-Pressure Respiration, Intrinsic
Pulmonary Gas Exchange*
Pulmonary Surfactants / metabolism*,  therapeutic use
Rats, Sprague-Dawley
Respiration, Artificial / methods
Reg. No./Substance:
0/Pulmonary Surfactants

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