Document Detail

Physiological dead space/tidal volume ratio during face mask, laryngeal mask, and cuffed oropharyngeal airway spontaneous ventilation.
MedLine Citation:
PMID:  9873966     Owner:  NLM     Status:  MEDLINE    
OBJECTIVE: To compare the physiological dead space/tidal volume ratio and arterial to end-tidal carbon dioxide tension (ETCO2) difference during spontaneous ventilation through a face mask, a laryngeal mask (LMA), or a cuffed oropharyngeal airway. DESIGN: Prospective, randomized, cross-over study. SETTING: Inpatient anesthesia at a university department of orthopedic surgery. PATIENTS: 20 ASA physical status I and II patients, without respiratory disease, who underwent ankle and foot surgery. INTERVENTIONS: After a peripheral nerve block was performed, propofol anesthesia was induced and then maintained with a continuous intravenous (i.v.) infusion (4 to 6 mg/kg/h). A face mask, a cuffed oropharyngeal airway, or an LMA were placed in each patient in a random sequence. After 15 minutes of spontaneous breathing through each of the airways, ventilatory variables, as well as arterial, end-tidal, and mixed expired CO2 partial pressure, were measured, and physiological dead space/tidal volume ratio was calculated. MEASUREMENTS AND MAIN RESULTS: Expired minute volume and respiratory rate (RR) were lower with LMA (5.6 +/- 1.2 L/min and 18 +/- 3 breaths/min) and the cuffed oropharyngeal airway (5.7 +/- 1 L/min and 18 +/- 3 breaths/min) than the face mask (7.1 +/- 0.9 L/min and 21 +/- 3 breaths/min) (p = 0.0002 and p = 0.013, respectively). Physiological dead space/tidal volume ratio and arterial to end tidal CO2 tension difference were similar with the cuffed oropharyngeal airway (3 +/- 0.4 mmHg and 4.4 +/- 1.4 mmHg) and LMA (3 +/- 0.6 mmHg and 3.7 +/- 1 mmHg) and lower than with the face mask (4 +/- 0.5 mmHg and 6.7 +/- 2 mmHg) (p = 0.0001 and p = 0.001, respectively). CONCLUSION: Because of the increased dead space/tidal volume ratio, breathing through a face mask required higher RR and expired minute volume than either the cuffed oropharyngeal airway or LMA, which, in contrast, showed similar effects on the quality of ventilation in spontaneously breathing anesthetized patients.
A Casati; G Fanelli; G Torri
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Publication Detail:
Type:  Clinical Trial; Comparative Study; Journal Article; Randomized Controlled Trial    
Journal Detail:
Title:  Journal of clinical anesthesia     Volume:  10     ISSN:  0952-8180     ISO Abbreviation:  J Clin Anesth     Publication Date:  1998 Dec 
Date Detail:
Created Date:  1999-03-11     Completed Date:  1999-03-11     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  8812166     Medline TA:  J Clin Anesth     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  652-5     Citation Subset:  IM    
Department of Anesthesiology, University of Milan, Italy.
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MeSH Terms
Analysis of Variance
Anesthetics, Intravenous / administration & dosage
Ankle / surgery
Carbon Dioxide / blood,  metabolism
Cross-Over Studies
Foot / surgery
Intubation / instrumentation*
Laryngeal Masks*
Middle Aged
Nerve Block
Oxygen / blood
Partial Pressure
Propofol / administration & dosage
Prospective Studies
Respiratory Dead Space / physiology*
Tidal Volume / physiology*
Reg. No./Substance:
0/Anesthetics, Intravenous; 124-38-9/Carbon Dioxide; 2078-54-8/Propofol; 7782-44-7/Oxygen

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

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