Inhalation of carbon dioxide

Inhalation of carbon dioxide causes the breathing rate to increase (Table 7.6) 10% CO2 in air can only be endured for a few minutes at 25% death can result after a few hours exposure. 

The antimony electrode used by Rosenfeldt et al. [156] did respond proportionally to the myocardial pH changes in dogs produced by infusion of sodium bicarbonate or inhalation of carbon dioxide. However, pH measured by the antimony electrodes was consistently about 0.26 units higher than that which was measured with the Paratrend optical... 

Perna, G., Gabriele, A., Perna, G., Bertrani, A., Caldirola, D. and Bellodi L. (1995) Hypersensitivity to inhalation of carbon dioxide and panic attacks. Psychiatry Res 57 267-273. 

Craig FN, Blevins WV and Cummings EG (1970). Exhausting work limited by external resistance and inhalation of carbon dioxide. J Appl Physiol, 29, 847-851. 

In the Waddell and Butler (1959) method for determining intracellular pH, three measurements are required the external pH, and the extracellular and intracellular concentrations of an indicator ion to which the membrane is impermeable (it must be freely permeable to the neutral species). These authors used a colourless, fluorescent indicator 5,5-dimethyloxazolidine-2,4-dione, DMO 10.38), a weak acid of 6.13 at 37°C. By this method, the pH inside resting muscle (dog) was found to be 7.04, but inhalation of carbon dioxide brought it down to 6.6. Using a radioactive form of this indicator, Addanki, Cahill and Sotos (1967) found pH 7.74 inside resting mitochondria. The indicator is considered to be safe to use in patients. 

Bredt DS, Snyder SEl Nitric oxide, a novel neuronal messenger. Neuron 8 3—11, 1992 Brouette T, Anton R Clinical review of inhalants. Am J Addict 10 79-94, 2001 Brown ES, Nejtek VA, Perantie DC, et al Quetiapine in bipolar disorder and cocaine dependence. Bipolar Disord4 406 11, 2002 Bushnell PJ, Evans EIL, Palmes ED Effects of toluene inhalation on carbon dioxide production and locomotor activity in mice. Fundam Appl Toxicol 5 971-977, 1983... 

The main function of the respiratory system is to exchange oxygen and carbon dioxide between the blood and the inhaled air. In 1 minute a normal person at rest uses an estimated 250 ml of oxygen and expels approximately 200 ml of carbon dioxide. Approximately 8 L of air are breathed per minute. Only a fraction of the total air within the lung is exchanged with each breath. These demands increase significantly with physical exertion. 

No studies were located regarding excretion of bromomethane in humans after inhalation exposure. In animals exposed to bromomethane vapors, excretion occurs mainly by expiration of carbon dioxide or by urinary excretion of nonvolatile metabolites (Bond et al. 1985 Jaskot et al. 1988 Medinsky et al. 1985). Only small amounts are excreted in the feces. Very little parent bromomethane is exhaled (Jaskot et al. 1988 Medinsky et al. 1985), and tissue levels of parent bromomethane decrease with a half-life of only about 15-30 minutes (Honma et al. 1985 Jaskot et al. 1988). Half-lives for clearance of metabolites from the body and most tissues range from 2 to 10 hours (Honma et al. 1985 Jaskot et al. 1988). 

Studies in animals indicate about 30-40% of an inhaled dose of carbon tetrachloride in excreted in expired air and about 32-62% is excreted in feces (McCollister et al. 1951 Paustenbach et al. 1986a). Relatively low amounts are excreted in urine. Nearly all of the material in expired air is parent carbon tetrachloride, with only small amounts of carbon dioxide. The identity of the nonvolatile metabolites in feces and urine was not determined. 

With the exception of nitrous oxide, all inhaled anesthetics in current use cause a dose-dependent decrease in tidal volume and an increase in respiratory rate. However, the increase in respiratory rate is insufficient to compensate for the decrease in volume, resulting in a decrease in minute ventilation. All volatile anesthetics are respiratory depressants, as indicated by a reduced response to increased levels of carbon dioxide. The degree of ventilatory depression varies among the volatile agents, with isoflurane and enflurane being the most depressant. All volatile anesthetics in current use increase the resting level of Paco2 (the partial pressure of carbon dioxide in arterial blood). 

Unless the proportion of ozone is exceedingly small, the inhalation of ozomsed air by human beings is liable to be accompanied by serious disturbances in the animal organism. The lung tissue is injured, the oxygen intake increased, and the output of carbon dioxide decreased.7 Exposure for a couple of hours to a concentration of 15 to 20 parts of ozone per million of air is not without risk to life, and even 1 part of ozone per million of air irritates the respiratory tract.8 This latter... 

Carbon monoxide is very toxic by inhalation TLV 50ppm. Prepare by slow addition of anhydrous formic acid to concentrated sulphuric acid at 90-100°C (frothing tends to be a problem). One millilitre of formic acid generates 26.6 mmoles of gas. The CO is contaminated with small amounts of carbon dioxide and sulphur dioxide which may be removed by passage over potassium hydroxide or the commercial product Ascarite (sodium hydroxide on silica). Dispose of carbon monoxide by slow venting in an efficient hood. 

There are three respiratory effects. First, inhalation resistance is imposed by the filter canister, inhalation valve and, to some extent, the airflow pattern. Secondly, exhalation resistance is imposed by the exhale valve and to some extent the exhale valve deadspace design. Thirdly, the internal volume of the respirator increases the respiratory deadspace, which can cause build-up of carbon dioxide. 

Respiratory depression was estimated in healthy young subjects in whom a respiratory stimulus response curve was determined in response to inhalation of three mixtures of carbon dioxide in oxygen. Simultaneous measurements were made of alveolar ventilation and alveolar C02 tension at each gas mixture. These provided the data for the curves. A control and two postdrug curves were obtained. The degree of displacement of these curves to the right repre sented respiratory depression. 

Human Toxicity Poisoning may occur by ingestion, absorption through injured skin or inhalation of hydrogen cyanide, liberated by action of carbon dioxide or other acids. Strong solns are corrosive to skin. For symptoms see Hydrogen Cyanide. 

Walter, G. L. 1999. Effects of carbon dioxide inhalation on hematology, coagulation and serum clinical chemistry values in rats. Toxicologic Pathology 27 217-225. 

Respiratory System Inhalation of oxygen at 1 atm or above causes a small degree of respiratory depression in normal subjects, presumably as a result of loss of tonic chemoreceptor activity. However, ventilation typically increases within a few minutes of oxygen inhalation because of a paradoxical increase in the tension of carbon dioxide in tissues, a result of increased oxyhemoglobin in venous blood, which causes less efficient removal of carbon dioxide from the tissues. 

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