A multicompartment model of carboxyhemoglobin and carboxymyoglobin responses to inhalation of carbon monoxide

Abstract

We have developed a model that predicts the distribution of carbon monoxide (CO) in the body resulting from acute inhalation exposures to CO. The model includes a lung compartment, arterial and venous blood compartments, and muscle and nonmuscle soft tissues with both vascular and nonvascular subcompartments. In the model, CO is allowed to diffuse between the vascular and nonvascular subcompartments of the tissues and to combine with myoglobin in the nonvascular subcompartment of muscle tissue. The oxyhemoglobin dissociation curve is represented by a modified Hill equation whose parameters are functions of the carboxyhemoglobin (HbCO) level. Values for skeletal muscle mass and cardiac output are calculated from prediction formulas based on age, weight, and height of individual subjects. We demonstrate that the model fits data from CO rebreathing studies when diffusion of CO into the muscle compartment is considered. The model also fits responses of HbCO to single or multiple exposures to CO lasting for a few minutes each. In addition, the model reproduces reported differences between arterial and venous HbCO levels and replicates predictions from the Coburn-Forster-Kane equation for CO exposures of a 1- to 83-h duration. In contrast to approaches based on the Coburn-Forster-Kane equation, the present model predicts uptake and distribution of CO in both vascular and tissue compartments during inhalation of either constant or variable levels of CO.

Stability of hemoglobin mass over 100 days in active men

“…where K ϭ (ambient barometric pressure mmHg ϫ 273 o K)/(760 mmHg ϫ ambient temperature o K); MCO is CO volume administered into the system minus CO volume not bound to hemoglobin (calculated as the sum of CO volume remaining in the spirometer and the lung, as well as CO volume exhaled during the 7 min between disconnecting the subject from the spirometer and the final blood sample), which was then multiplied by 0.99 to correct for 1% loss of the CO dose to myoglobin (2,16); ⌬%HbCO is the difference between %HbCO at baseline and %HbCO in the blood samples 9 min after CO administration; and 1.39 is Hüfner's value for the CO binding capacity of hemoglobin (1.39 ml/g) (8). The 9-min concentration was calculated as the mean of the 8-and 10-min blood samples.…”

A mathematical modeling approach to risk assessment for normal and anemic women chronically exposed to carbon monoxide from biomass-fueled cookstoves

“…Although CO is rapidly absorbed into the blood via the lungs, the uptake by muscle is delayed (8,9). Furthermore, CO washout from the body is a biexponential process (10).…”

A carbon monoxide transport model of the human respiratory system applied to urban atmosphere exposure analysis

“…That relation was based on Bruce and Bruce (2003). The myoglobin concentration in the muscles is 0.0053 g/ml (Coburn and Mayers, 1971).…”

“…Selvakumar, Sharan and Singh (1992) applied their model to high altitudes and Sharan and Selvakumar (1999) to the end-expired breath technique. The model of Bruce and Bruce (2003) also divides the human body into compartments, including the muscular and non-muscular tissues. The present model has characteristics of the lung representation of Selvakumar, Sharan and Singh (1992) and Sharan and Selvakumar (1999), and the tissue representation of Bruce and Bruce (2003).…”

“…The model of Bruce and Bruce (2003) also divides the human body into compartments, including the muscular and non-muscular tissues. The present model has characteristics of the lung representation of Selvakumar, Sharan and Singh (1992) and Sharan and Selvakumar (1999), and the tissue representation of Bruce and Bruce (2003). The carbon monoxide transport model of the human respiratory system developed in the present work considers the exchanges of CO, O 2 and CO 2 .…”