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Control of Carbon Dioxide in Modified Mapleson A and D (Hafnia) Anaesthetic Systems. An Experimental Model
Author(s) -
Andersen P. K.
Publication year - 1981
Publication title -
acta anaesthesiologica scandinavica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.738
H-Index - 107
eISSN - 1399-6576
pISSN - 0001-5172
DOI - 10.1111/j.1399-6576.1981.tb01664.x
Subject(s) - medicine , hyperventilation , absorption (acoustics) , carbon dioxide , anesthesia , hypocapnia , chemistry , materials science , organic chemistry , acidosis , composite material , hypercapnia
The effects of varying ventilations (V e ) and fresh gas flows (FGF) on end‐expiratory CO 2 (F eco 2 ) levels were investigated in an experimental model lung, employing the Hafnia modification of the Mapleson A and D anaesthetic systems during CO 2 ‐absorption and CO 2 ‐wash‐out (rebreathing). Identical results were found in both systems: F eco 2 was constant and independent of FGF with CO 2 ‐absorption and constant V e , whereas rebreathing resulted in increasing F eco 2 levels as FGF was decreased. As control of F eco 2 in the rebreathing systems by regulating FGF could only take place within F eco 2 levels higher than that determined by V e at complete CO 2 ‐absorption, e. g. for the Hafnia A and D rebreathing systems, control of FGF necessitates relative hyperventilation. F eco 2 with constant FGF decreased with increasing V e during CO 2 ‐absorption, as well as during rebreathing, although this decrease was less in the rebreathing systems. Thus a decrease in F eco 2 with rising V e can be avoided and hypocapnia prevented. The results agree with those obtained in clinical studies.