Carbon Monoxide Headquarters

## Carbon Monoxide

__Coburn-Forster-Kane Equation:__

The Coburn-Forster-Kane equation is the most sophisticated approach to modeling carbon monoxide uptake by humans and animal available. Disadvantages of its use are the large number of variables that it contains and the fact that value of many of the variables must in turn be obtained from other equations.

{ A [HbCO]_{t} - (BV_{CO} + PI_{CO}) } / { A [HbCO]_{0} - (BV_{CO} + PI_{CO}) } = e^{-tAVbB} }

__Terms of Equation:__

**A** = P_{c,O2} / M [HbO_{2}]

**[HbCO]**_{t}, *see below*

**B** = 1 / DL_{CO} + PL / VA

**V**_{CO}, *see below*

**PI**_{CO}, *see below*

**[HbCO]**_{0}, *see below*

**e**, *see below*

**t**, *see below*

**V**_{b}, *see below*

__Where:__

**P**_{c,O2} is the average partial pressure of O_{2} in lung capillaries (mm Hg); at sea level PI_{O2} (159) - 49 = 110

........... **PI**_{O2} = 148.304 - 0.0208 ^{.} PI_{CO}

**M** is the ratio of the affinity of blood for CO to that for O_{2}, approximately __218__

**[HbO**_{2}] is ml of O_{2} per ml blood, **or** = 0.22 - [HbCO]_{t}

**[HbCO]**_{t} is ml of CO per ml blood at time t, **or** = [COHb%]_{t} ^{.} 0.0022 {**term to be solved for**}

**DL**_{CO} is diffusivity of the lung for CO (ml/min./mm Hg), **or** = 35VO_{2} ^{.} e^{0.33}

........... **VO**_{2} = RMV / 22.274 - 0.0309

........... **RMV** is respiratory minute volume (L/min.)

**PL** is barometric pressure minus the vapor pressure of water (ie. 49) at body temp. (mm Hg)

**V**_{CO} is rate of endogenous CO production (ml/min.); approximately 0.007 ml/min.

**PI**_{CO} is partial pressure of CO in inhaled air (mm Hg)

**V**_{A} is alveolar ventilation rate (ml/min), **or** = 0.933 V_{E} - 132 *f*

........... **V**_{E} is ventilation volume (ml/min.)

........... *f* is ventilation frequency

**[HbCO]**_{0} is ml of CO/ml blood at the beginning of the exposure (approximately 0.8% COHb, **or** 0.0176 ml CO/ml blood for a non-smoker)

**e** is base of natural logarithms (2.7182)

**t** is exposure duration (min.)

**V**_{b} is blood volume (ml); assume 74 ml/kg body weight

###### ...... Last changed 02/12/00

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