Document Detail

Application of a valveless anesthesia circuit for deep diving.
MedLine Citation:
PMID:  8000284     Owner:  NLM     Status:  MEDLINE    
The Mapleson E breathing circuit used in anesthesia has no valves or CO2-absorbent canisters and thus entails low resistance to breathing and has low requirements for fresh gas flow (FGF). The authors investigated whether these advantages would make a circuit, modified for hyperbaric use, able to support ventilation during heavy work on the surface and at deep depths with reduced FGF rates. The current recommended FGF for free-flowing diving circuits is 170 liters/min. Six Navy divers participated in 10-min graded exercise sequences, peak workload 220 W. Measurements were made of inspired and end-tidal concentrations of CO2, tidal volume, respiratory rate, and CO2 production at both sea level and 2.7 MPa dry environment. At sea level, all six divers were able to finish their exercises using the modified circuit with all tested rates of FGF. At 2.7 MPa the exercise sequence could be finished by all subjects when FGF was 170 liter/min and by five subjects when FGF was 127.5 liter/min, but high end-tidal CO2 measurements and hypercapnia symptoms were common at 127.5 liter/min. None of the subjects was able or allowed to finish the exercise sequence when FGF was 85 liter/min. Lower work-loads of 75 and 150 W for up to 4 min were completed easily by all subjects at all three rates of FGF. We conclude that this circuit concept warrants further study because it requires lower FGF than is currently used with open-circuit helmets and is valveless; how much of a reduction in FGF could be tolerated with heavy work at depths such as 2.7 MPa requires further study.
K M Zwingelberg; M J Jaeger
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Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Undersea & hyperbaric medicine : journal of the Undersea and Hyperbaric Medical Society, Inc     Volume:  21     ISSN:  1066-2936     ISO Abbreviation:  Undersea Hyperb Med     Publication Date:  1994 Dec 
Date Detail:
Created Date:  1995-01-24     Completed Date:  1995-01-24     Revised Date:  2004-11-17    
Medline Journal Info:
Nlm Unique ID:  9312954     Medline TA:  Undersea Hyperb Med     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  443-58     Citation Subset:  IM; S    
United States Navy Experimental Diving Unit, Panama City, Florida 32507.
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MeSH Terms
Anesthesia, Closed-Circuit / instrumentation*
Carbon Dioxide / metabolism
Diving* / physiology
Dyspnea / etiology
Equipment Design
Exercise / physiology
Respiration / physiology*
Tidal Volume
Reg. No./Substance:
124-38-9/Carbon Dioxide

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

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