Hyperventilation syndrome (hyperventilationsyndrome) is a group of syndromes caused by hyperventilation exceeding physiological metabolism. It is characterized in that clinical symptoms can be replicated by an over-ventilation challenge test. The traditional notion is that factors such as anxiety and stress response induce hyperventilation required for superphysiological metabolism, and clinical symptoms can be explained by hyperventilation and respiratory alkalosis. Recent studies on the pathogenesis of hyperventilation syndrome have made great progress, and the role of respiratory central regulation abnormalities in the pathogenesis of hyperventilation syndrome has received increasing attention.
Recent studies on the pathogenesis of hyperventilation syndrome have made great progress, and the role of respiratory central regulation abnormalities in the pathogenesis of hyperventilation syndrome has received increasing attention.
One of the main functions of breathing is to maintain plasma carbon dioxide partial pressure (paco2) within a narrow and stable physiological range. This function is accomplished through several processes: a rhythmic renewal of the gas in the alveoli, a gas exchange between the alveolar membrane and the blood, transport of the gas in the blood, and exchange of gas with the tissue. Breathing is regulated by the respiratory center of the brainstem. The activity of the brainstem respiratory center is regulated by the negative feedback of metabolic changes on the chemoreceptors, and on the other hand by the high-level neural structures above the brainstem (cerebral cortex, hypothalamus). Impact. In daily life, the effects of metabolism and high-level neural structures are coordinated, allowing the body to adapt to changes in the internal and external environment, keeping the plasma carbon dioxide partial pressure within a constant physiological range. For example, during speech, singing, thinking, and exercise, metabolic control interacts with the effects of high-level neural structures to avoid hyperventilation or inadequate ventilation.
Excitatory test pulmonary ventilation function arterial blood gas analysis repeated breath test respiratory exercise examination
To date, the diagnosis of hyperventilation syndrome is still limited to clinical diagnosis, mainly based on suspicious symptoms, hyperventilation stimulation test partially or completely replicate the main symptoms, in the absence of other organic diseases, to make a clinical diagnosis.
The nijmegen Symptoms Questionnaire lists 16 common symptoms of hyperventilation syndrome, including chest pain, mental stress, blurred vision, dizziness, confusion, or inattention to the surrounding conditions, deep and fast breathing, shortness of breath, chest Tightness or discomfort, bloating, finger numbness or acupuncture, difficulty breathing, stiff fingers or upper limbs, tightness around the lips, cold hands and feet, palpitations or palpitation, anxiety. Score according to the frequency of symptoms: 0 = never, 1 = occasionally, 2 = sometimes, 3 = often, 4 = frequent. Sixteen symptom total scores reached or exceeded 23 as a symptomatic diagnostic criteria. A small number of patients are frequent acute episodes. The scoring method for such patients is: 1=0-3 times/month, 2=1-2 times/week, 3=3-6 times/week, 4 = 1 time or more per day.
Differential diagnosis of hyperventilation:
In clinical practice, there are still some problems in clinical diagnostic criteria, such as certain chronic fatigue syndrome, chronic pain patients, or psychosomatic patients with somatoform disorders, whose clinical manifestations are similar to hyperventilation syndrome, at least partially consistent with the diagnosis. standard. In addition, in some patients with typical hyperventilation syndrome, the total score of the nijmegen symptomology questionnaire did not reach the standard of 23 or higher. Therefore, objective diagnostic indicators, especially objective criteria that reflect the pathogenesis of respiratory control abnormalities, are helpful for diagnosis and differential diagnosis. Possible indicators are: blood gas paco2 reduction, hardonk and beumer coefficient, co2 positive feedback regulation and abnormal breathing patterns.
The reduction of blood gas paco2 is the direct respiratory physiological basis for diagnosis, which indicates that the patient is now in the acute exacerbation of symptoms, hyperventilation, acute respiratory alkalosis. Unfortunately, the vast majority of patients are chronic and have a short episode (10 minutes or so). Routine blood gas analysis tests capture acute respiratory alkalosis. According to lum, about one-third of patients have normal or low blood gas analysis. Therefore, normal blood gas analysis cannot exclude the diagnosis. Percutaneous paco2 dynamic monitoring is a method worthy of advocating. It not only reflects the blood gas changes during the patient's onset, but also provides the symptoms of blood gas abnormality by recording the life diary, and the reliability of the diagnosis is strong. However, most routine experiments are not equipped and clinical applications are limited.
The hyperventilation challenge test has been used to induce a typical form of breathing in hyperventilation syndrome as a diagnostic criterion. To this end, hardonk and beumer recorded the end-tidal co2 concentration (fetco2) in the resting state of the patient, and after the spontaneous hyperventilation, recorded the recovery period of fetco2, the ratio of fetco2 at rest to three minutes and fetco2 at rest 1.5 (hardonk and beumer coefficient) as a diagnostic criterion. The work of hardonk and beumer failed to be verified by other scholars. The cause of the disagreement may be related to the different age distribution of the patients studied. During clinical application, we observed that the hardonk and beumer coefficients are neither specific nor sensitive.
Folgering and colla studied the diagnostic value of the positive feedback phenomenon of co2, and observed 50 patients with hyperventilation syndrome, and found that 18 patients showed significant positive feedback of co2.
Abnormal breathing patterns, especially hyperventilation induced by mouthful breathing, have a high specificity of diagnosis (95%), 50% sensitivity in younger groups (20 to 28 years old), and younger and middle-aged groups (29-60) Years old) is less sensitive, only 30%.
Firedman studied the diagnostic value of the breath holding test. Combine the breath holding test with the hyperventilation challenge test. Before the hyperventilation challenge test, the paralyzed patient deeply inhaled to the tlc position, immediately pinched the nose with his fingers, until the screen could not breathe, and recorded the breath holding time. The ratio of the breath holding time after the test to the breath holding time before the test was used as the hyperventilation index. From the data he reported, the breath holding test was simple and easy, with high specificity and sensitivity.