M. Abel et Jb. Eisenkraft, PERFORMANCE OF ERRONEOUSLY FILLED SEVOFLURANE, ENFLURANE AND OTHER AGENT-SPECIFIC VAPORIZERS, Journal of clinical monitoring, 12(2), 1996, pp. 119-125
Objective. Erroneous filling of an agent-specific anesthesia vaporizer
may result in concentration and potency outputs that are very differe
nt from those expected from the concentration dial setting. Enflurane
and sevoflurane have relatively similar saturated vapor pressures (SVP
s 175 mmHg and 160 mmHg, respectively, at 20 degrees C) and potencies
(MACs 1.68% and 2%, respectively). We derived an equation to relate th
e vapor concentration output of an agent-specific vaporizer to the gas
inflow splitting ratio (SR) created by the vaporizer and the SVP of t
he potent inhaled agent. Methods. To test the validity of this equatio
n, we filled an Enfluratec 4 enflurane vaporizer with sevoflurane and
a Penlon PPV Sigma sevoflurane vaporizer with enflurane and compared t
he vapor concentration outputs with our predictions. Results. The equa
tion accurately predicted the vapor concentration outputs of the erron
eously filled enflurane and sevoflurane vaporizers. The potency (MAC)
output of the erroneously filled Enfluratec 4 vaporizer decreased by 2
2%-33%, and that of the Penlon PPV Sigma sevoflurane vaporizer increas
ed by 21%-31% from those expected from the concentration dial settings
. Conclusion. When an agent-specific variable bypass vaporizer is erro
neously filled, the vapor concentration outputs can be predicted from
the splitting ratio created by setting the vaporizer concentration dia
l and the SVP of the agent.