## Abstract

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 PO_{2} changes with time. The parameters of the power equation were solved by using nonlinear regression for the reduction in vital capacity (ΔVC) in humans: %ΔVC = 0.0082 × t^{2}(PO_{2}/101.3)^{4.57}, where t is the time in hours and PO_{2} is expressed in kPa. The recovery of lung volume is ΔVC_{t} = ΔVC_{e} × e^{-(-0.42 + 0.00379PO2)t}, where ΔVC_{t} is the value at time t of the recovery, ΔVC_{e} is the value at the end of the hyperoxic exposure, and PO_{2} 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 = t^{2} (PO_{2}/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 = [In(t) - 9.63 +3.38 × n(PO_{2}/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: K_{t} = K_{e} - e^{-0.079t}, where K_{t} and K_{e} 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.

Original language | English |
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Pages (from-to) | 248-256 |

Number of pages | 9 |

Journal | Journal of Applied Physiology |

Volume | 92 |

Issue number | 1 |

DOIs | |

State | Published - 2002 |

## Keywords

- Central nervous system oxygen toxicity
- Hyperbaric oxygen
- Pulmonary oxygen toxicity

## ASJC Scopus subject areas

- Physiology
- Physiology (medical)

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