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1 Israel Naval Medical Institute and 2 Israel Defense Force Medical Corps, Haifa 31080; and 3 Department of Statistics, University of Haifa, Haifa 31905, Israel
10.1152/japplphysiol.00434.2001.
The
power expression for cumulative oxygen toxicity and the exponential
recovery were successfully applied to various features of oxygen
toxicity. From the basic equation, we derived expressions for a
protocol in which PO2 changes with time. The
parameters of the power equation were solved by using nonlinear
regression for the reduction in vital capacity (
VC) in humans:
%
VC = 0.0082 × t2(PO2/101.3)4.57,
where t is the time in hours and PO2
is expressed in kPa. The recovery of lung volume is
VCt =
VCe ×
e
(
0.42 + 0.00379PO2)t,
where
VCt is the value at time t
of the recovery,
VCe is the value at the end of the
hyperoxic exposure, and PO2 is the prerecovery
oxygen pressure. Data from different experiments on central nervous
system (CNS) oxygen toxicity in humans in the hyperbaric chamber
(n = 661) were analyzed along with data from actual
closed-circuit oxygen diving (n = 2,039) by using a
maximum likelihood method. The parameters of the model were solved for the combined data, yielding the power equation for active diving: K = t2
(PO2/101.3)6.8, where t
is in minutes. It is suggested that the risk of CNS oxygen toxicity in
diving can be derived from the calculated parameter of the normal
distribution: Z = [ln(t)
9.63 +3.38 × ln(PO2/101.3)]/2.02. The recovery time constant for CNS oxygen toxicity was calculated from
the value obtained for the rat, taking into account the effect of body
mass, and yielded the recovery equation: Kt = Ke × e
0.079t, where
Kt and Ke are the values
of K at time t of the recovery process and at the
end of the hyperbaric oxygen exposure, respectively, and t
is in minutes.
hyperbaric oxygen; pulmonary oxygen toxicity; central nervous system oxygen toxicity
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