The medical term for low serum carbon dioxide levels is hypocapnia. It is usually caused by hyperventilation -- known as acute hypocapnia -- but can also result from asthma or hindrances to cerebral autoregulation, which is the disrupted regulation of blood flow in the brain due to tumors, hematomas or injuries. Doctors also sometimes induce hypercapnia in newborn infants to prevent injury or death in the event that the infants need mechanical ventilation, according to the medical Journal "Clinics in Perinatology."
Hypocapnia reduces blood flow through vasoconstriction, or narrowed blood vessels. Reduced blood flow and bronchoconstriction, or narrowed bronchial tubes, reduces blood oxygenation. These characteristics of hypocapnia place excess pressure on the heart. Such cardiovascular pressure can lead to irregular heartbeats as well as angina pectoris, which is chest discomfort that increases in severity over time. Angina pectoris often causes extreme pain, and can lead to cardiac arrest. Sustained or recurrent hypocapnia can cause persistent cardiovascular disorders like heart disease.
According to "Behavioral and Psychological Approaches to Breathing Disorders," hypocapnia causes respiratory alkalosis, which is an elevation in blood pH. Respiratory alkalosis results in a reduction of serum calcium ions and arterial bicarbonate, which stimulates the sympathetic nervous system. Sympathetic stimulation caused by hypocapnia can result in numbness, dizziness, fainting, seizures, tingling sensations, paralysis, cold flashes and blurred vision, cumulatively known as neuronal irritability, or hyperirritability. As a result, doctors can mistake chronic hypocapnia for disorders with similar symptoms, like epilepsy.
"Neurology and General Medicine" indicates that hypocapnia causes sharp reductions of blood serum phosphate ions, clinically known as hypophosphatemia. This aspect of hypocapnia increases the likelihood of cardiovascular and respiratory difficulties because hypophosphatemia results in the destruction of red blood cells, further reducing oxygenation and causing damage that may persist even after treatment for hypocapnia. Other direct effects of hypophosphatemia include confusion, muscle weakness, heart damage, anemia, disorientation and coma.
Is This an Emergency?
- "Physiotherapy for Respiratory and Cardiac Problems: Adults and Paediatrics"; Jennifer A. Pryor and Ammani S. Prasad; 1993
- "Behavioral and Psychological Approaches to Breathing Disorders"; Beverly H. Timmons and Ronald Ley; 1994
- "Neurology and General Medicine"; Michael J. Aminoff; 2008
- "European Neurology"; Cerebral Blood Flow Autoregulation and Graded Hypercapnia; M.E. Raichle and H.L. Stone; March 1971
- "Clinics in Perinatology"; Hypocapnia and Hypercapnia in Respiratory Management of Newborn Infants; N. Ambalavanan and W.A. Carlo; September 2001