Health effects of carbon dioxide

• Inspired air contains 0.03%, mixed expired gas 3.5-4% and alveolar gas contains 3-4%. Breathing of 5% of CO2 in air or oxygen is tolerable but high concentration results in dyspnoea, headache.

Above 10%, narcotic effect becomes more marked and at 30% produces isoelecric EEG and coma, which means that the health effects of carbon dioxide sometimes need to monitored early.

• One of the health effects of carbon dioxide is Hypercapnia. It itself depresses heart, produces increase in catecholamine levels, multifocal ventricular ecotopics.

• A breathing mixture of 6% causes acute distress with disorientation, dyspnoea, anxiety and erratic behavior. 8% concentration causes depression of cerebral cortex, this being one of the health effects of carbon dioxide .

• The pain threshold is elevated, with loss of mental activity and loss of visceral sensation.

• At 5-7% concentration it causes marked increase in cerebral blood flow and fall in cerebral vascular resistance. The diameter of cerebral vessels is increased due to CO2 inhalation and active dilatation of pail vessels.

Common health effects of carbon dioxide include :

• There is fall in peripheral vascular resistance but there is increase in mean arterial pressure. There is increase in blood flow towards skin and so more chances of oozing.

• Directly it reduces contractile force of heart but indirectly increases cardiac output. It increases the sympathetic response, although cardio health effects of carbon dioxide are many.

• The ECG changes are—no change in PR interval, AV nodal beats, ST segment elevation or depression, inverted T wave and QRS changes. It produces all types of arrhythmias.

• In high concentration it increases sympathetic output and enhances release of catecholamines.

Few other health effects of carbon dioxide are :

• Carbon dioxide stimulates respiration by rate and depth secondary to direct stimulation of respiratory center and by direct action on carotid and aortic bodies.

• Higher concentration of carbon dioxide produces respiratory distress, dyspnoea and headache. Above 10% concentration it causes marked narcosis and at 30% there is coma and central depression of breathing. Respiratory distress is one of the many respiratory health effects of carbon dioxide .

• Systemic blood pressure, cardiac output and heart rate progressively increase with increase in carbon dioxide tension due to direct sympathetic stimulation.

At high Paco2 there is cardiovascular or myocardial depression. Peripheral vasodilatation occurs with hypercapnia and vasoconstriction with hypocapnia. This is considered to be one of the critical health effects of carbon dioxide .


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