Hyperventilation syndrome pathophysiology: Difference between revisions
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The pathophysiology of hyperventilation syndrome can be divided into psycopathology, abnormalities of regulatory system, mechanism of pulmonary, and neurologic symptoms. | The pathophysiology of hyperventilation syndrome can be divided into psycopathology, abnormalities of regulatory system, mechanism of pulmonary, and neurologic symptoms. | ||
=== | ===Psychopathology=== | ||
There is an association between hyperventilation syndrome and psychological conditions such as panic disorder, but whether the psychological condition is primary or secondary is often unclear. Somatic and respiratory symptoms are common in patients with psychological distress. “Disproportionate breathlessness" is associated with depression, anxiety, bereavement, and resentment.<ref name="pmid2278552">{{cite journal |author=Howell JB |title=Behavioural breathlessness |journal=[[Thorax]] |volume=45 |issue=4 |pages=287–92 |year=1990 |month=April |pmid=2278552 |pmc=473775 |doi= |url= |accessdate=2013-05-28}}</ref> | There is an association between hyperventilation syndrome and psychological conditions such as panic disorder, but whether the psychological condition is primary or secondary is often unclear. Somatic and respiratory symptoms are common in patients with psychological distress. “Disproportionate breathlessness" is associated with depression, anxiety, bereavement, and resentment.<ref name="pmid2278552">{{cite journal |author=Howell JB |title=Behavioural breathlessness |journal=[[Thorax]] |volume=45 |issue=4 |pages=287–92 |year=1990 |month=April |pmid=2278552 |pmc=473775 |doi= |url= |accessdate=2013-05-28}}</ref> | ||
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1],Farman Khan, MD, MRCP [2]
Pathophysiology
The pathophysiology of hyperventilation syndrome can be divided into psycopathology, abnormalities of regulatory system, mechanism of pulmonary, and neurologic symptoms.
Psychopathology
There is an association between hyperventilation syndrome and psychological conditions such as panic disorder, but whether the psychological condition is primary or secondary is often unclear. Somatic and respiratory symptoms are common in patients with psychological distress. “Disproportionate breathlessness" is associated with depression, anxiety, bereavement, and resentment.[1]
Basis of Pulmonary symptoms
Imbalance between sensory signals from pulmonary and chest wall stretch receptors and motor signals from the motor cortex result in feelings of dyspnea. The greater the imbalance, the greater the severity of dyspnea.[2]
Basis of Neurologic symptoms
With decreasing arterial Carbon Dioxide levels (PaCO2), cerebral blood flow decreases in a linear fashion. Raichle and Plum has shown that a decrease of 1 mmHg of PaCO2 is associated with a 2 percent decrease in cerebral blood flow.[3] Reduction in cerebral blood flow in the setting of hyperventilation in combination with respiratory alkalosis may explain the neurologic symptoms such as paresthesias, headache, and light-headedness. In hyperventilation syndrome, respiratory alkalosis leads to acute changes in ionized serum calcium levels, which could result in paresthesias and/or tetany.
Regulating system dysfunction
Abnormalities in control system for ventilation, the reticular activating system, are important in the development of symptoms in some patients with hyperventilation syndrome. Under normal conditions, healthy individuals demonstrate regular breathing with no voluntary effort. Hypersensitivity of certain parts of the brain such as the hippocampus, medial prefrontal cortex, amygdala and its brain stem projections, also some times called “Fear Center,” have been associated with hyperventilation syndrome.[4] Increased sensitivity to carbon dioxide has also been proposed as a mechanism for hyperventilation syndrome and its association with psychological symptoms. An activated hypersensitive fear network leads to increased central respiratory drive, causing low PaCO2 levels.
HVS can occur as part of a panic attack. Despite the stigma, most patients are exaggerating symptoms but are in true distress.
Patients with HVS feel as though they cannot get enough air, but the opposite is true: they have too much oxygen and too little carbon dioxide in their blood. Hyperventilation is self-promulgating as rapid breathing causes carbon dioxide levels to continue to fall, and respiratory alkalosis (high blood pH) develops. This makes the symptoms worse, which causes the patient to try breathing even faster, perpetuating the cycle.
References
- ↑ Howell JB (1990). "Behavioural breathlessness". Thorax. 45 (4): 287–92. PMC 473775. PMID 2278552. Unknown parameter
|month=ignored (help);|access-date=requires|url=(help) - ↑ Schwartzstein RM, Manning HL, Weiss JW, Weinberger SE (1990). "Dyspnea: a sensory experience". Lung. 168 (4): 185–99. PMID 2122135.
|access-date=requires|url=(help) - ↑ Raichle ME, Plum F (1972). "Hyperventilation and cerebral blood flow". Stroke; a Journal of Cerebral Circulation. 3 (5): 566–75. PMID 4569138.
|access-date=requires|url=(help) - ↑ Magarian GJ (1982). "Hyperventilation syndromes: infrequently recognized common expressions of anxiety and stress". Medicine. 61 (4): 219–36. PMID 7045570. Unknown parameter
|month=ignored (help);|access-date=requires|url=(help)