Hyperventilation syndrome

　　过度通气综合征常见于女性，具有神经官能症的表现或有诱发精神紧张的因素。

　　1、精神性过度通气

　　这是呼吸性碱中毒的常见原因，但一般均不严重。严重者可以有头晕、感觉异常，偶尔有搐搦。常见于癔病发作患者。

　　2、代谢性过程异常

　　甲状腺机能亢进及发热等时，通气可明显增加超过了应排出的CO2量。可导致呼吸性碱中毒，但一般也不严重。但都说明通气量并非单单取决于体液中[H+]和PCO2，也与代谢强度和需氧情况有关。此时的通气过度可能是肺血流量增多通过反射性反应引起的。

　　3、乏氧性缺氧

　　乏氧性缺氧时的通气过度是对乏氧的代偿，但同时可以造成CO2排出过多而发生呼吸性碱中毒。常见于进入高原、高山或高空的人；胸廓及肺病变如肺炎、肺栓塞、气胸、肺淤血等引起胸廓、肺血管或肺组织传入神经受刺激而反射性通气增加的病人；此外，有些先天性心脏病患者，由于右至左分流增加而导致低张性低氧血症也能出现过度通气。这些均引起血浆H2CO3下降而出现呼吸性碱中毒。

　　4、中枢神经系统疾患

　　脑炎、脑膜炎、脑肿瘤、脑血管意外及颅脑损伤病人中有的呼吸中枢受到刺激而兴奋，出现通气过度。

　　5、水杨酸中毒

　　水杨酸能直接刺激呼吸中枢使其兴奋性升高，对正常刺激的敏感性也升高，因而会出现过度通气。

　　6、革兰氏阴性杆菌败血症

　　革兰氏阴性杆菌进入血路而繁殖的病人，在体温血压还没有发生变化时即可出现明显的通气过度。PCO2有低至17mmHg者。此变化非常有助于诊断。其机理尚不清楚，因为动物实验中未能成功复制此一现象。

　　7、人工呼吸过度

　　8、肝硬化

　　肝硬化有腹水及血NH3升高者可出现过度通气。可能系NH3对呼吸中枢的刺激作用引起的。当然，腹水上抬横隔也有刺激呼吸的作用，但是非肝硬化的腹水病人却无过度通气的反应。

　　9、代谢性酸中毒突然被纠正

　　例如使用NaHCO纠正代谢性酸中毒，细胞外液[HCO]浓度迅速升至正常，但通过血脑浆屏障很慢，约12～24小时，此时脑内仍为代谢性酸中毒，故过度通气仍持续存在。这就造成H2CO3过低的呼吸性碱中毒。

　　10、妊娠

　　有中等程度的通气增加，它超过CO2产量，目前认为系黄体酮对呼吸中枢的刺激作用，一些合成的黄体酮制剂也有此作用。妊娠反应期因呕吐、饮食不足可发生酮症酸中毒，妊娠反应期过后则可发生呼吸性碱中毒，有时引起手足搐搦。

　　Overventilation syndrome is prone to respiratory alkalosis. Due to overventilation, the partial pressure of carbon dioxide in the alveoli decreases excessively, and the concentration of carbon dioxide in the blood decreases excessively, leading to respiratory alkalosis complications. Clinical manifestations are relatively obvious, and symptoms such as asphyxia, shortness of breath, dizziness, irritability, abnormal sensations in the limbs and around the mouth, etc. Severe cases may have consciousness disorders, and the mechanism may be that the decrease in Pco2 causes vasoconstriction of the cerebral vessels and ischemia, and tetany is due to the decrease in plasma albumin and chronic acidosis.

　　Overventilation syndrome is often transient. Vertigo is very similar to rotational vertigo and dizziness in patients with vestibular dysfunction, but it can also manifest as dizziness, unbalanced feeling, and duration of symptoms is not fixed. Motion illusions usually last for a few seconds to minutes, while dizziness is often persistent, lasting 5-30 minutes, accounting for about 60%. Other accompanying symptoms include:

　　1. Neurological symptoms: fainting, visual disturbances, migraines, numbness and sensory abnormalities in limbs and around the mouth and face, sometimes with a warm sensation in the limbs, sweating or a cold feeling, most often on the left side. Inability to tolerate bright light and loud noises.

　　2. Cardiovascular symptoms: palpitations, tachycardia, chest pain, pressure sensation in the lower chest.

　　3. Respiratory symptoms: short and rapid breathing (difficult for patients to notice), asthma, chest pain, deep sighing, excessive yawning, air hunger, etc.

　　4. Gastrointestinal symptoms: dry mouth, difficulty swallowing, heartburn, hiccups, belching, etc.

　　5. Muscle symptoms: spasms, tremors, and convulsions.

　　6. Psychological symptoms: anxiety, emotional instability, personality disintegration, occasional feelings of unreality and hallucinations. Even irrational fear.

　　7. General symptoms: fatigue, weakness, inattention, memory decline, poor sleep, nightmares, emotional sweating, transient blackouts, etc. The frequency, duration, and severity of symptoms vary, and female patients tend to have more frequent attacks. Additionally, the presence of overventilation signs often affects the compensation of vertigo patients' vestibular system, delaying the acquisition of vestibular compensation.

　　To prevent overventilation syndrome, it is necessary to improve the quality of life, pay attention to a balance between work and rest, and when faced with unpleasant things, pay attention to regulating your emotions. It is best to talk with friends you get along with to vent your emotions, do not keep unpleasant emotions in your heart, and avoid factors that may trigger mental tension.

　　1. Appropriately vent your negative emotions and do not刻意 suppress them.

　　2. Be aware of the initial symptoms of overventilation syndrome so that you can remind yourself to relax and slow down your breathing in a timely manner.

　　3. If overventilation syndrome occurs repeatedly, it is advisable to seek appropriate psychological counseling.

　　4. Calm your emotions while slowing down and deepening your breath. If you can do this effectively, the condition usually improves rapidly within 5-10 minutes.

　　5. It is advisable to avoid staying up late and consuming stimulants such as coffee, tea, and caffeine, as well as drugs like Ecstasy and amphetamines.

　　Patients with overbreathing syndrome should have blood gas analysis, which shows decreased PaCO2 and increased pH. In patients with tachycardia, abnormalities can be found in the electrocardiogram.

　　1, Blood gas analysis: PaCO2 decreases; pH increases, which may be higher than 7.6.

　　2, Pulmonary function test: respiratory rate increases ≥16/min, pulmonary volume meter measurement often shows irregular breathing, and sigh-like breathing may occur intermittently, and the respiratory conditions of the upper and lower chest can be recorded separately to find that patients with this syndrome are mainly respiratory in the upper chest.

　　3, The determination of catecholamines in serum and changes in electrolytes can find increased catecholamines. Due to respiratory alkalosis, glycolysis accelerates, and inorganic phosphorus is transferred to the cell, so blood phosphorus is significantly reduced. Blood potassium may increase.

　　4, Electrocardiogram shows transient inversion of T waves, slight descent of ST segment, and prolongation of QT interval.

　　5, Electroencephalogram examination: 8 waves with high potential, increased amplitude of alpha waves, abnormal fast waves, and increased amplitude, and abnormal slow waves can also be seen, and spike waves can sometimes be seen.

　　6, The vestibular function is basically normal, but the amplitude of the slow phase may increase.

　　7, Auditory function is basically normal.

　　8, Autonomic nervous function testing, such as heart rate variability test, may show abnormalities.

　　Patients with overbreathing syndrome should have a light diet, eat more fresh vegetables and fruits, especially ventilating vegetables such as spinach, radish, bamboo shoots, celery, lotus root, etc. Avoid spicy foods such as chili and mustard. Habits such as smoking and drinking should be quit. Dietary therapy for overbreathing syndrome (the following information is for reference only, detailed information should be consulted with a doctor):

　　1, Radish and Tofu Soup

　　400 grams of radish, 200 grams of tofu. Wash the radish, peel and cut into strips, blanch in boiling water for a moment, remove and cool with cold water; cut the tofu into thick strips; heat oil in a frying pan, fry the chopped scallions, add soup, add radish strips and tofu strips, bring to a boil with high heat; when the radish is tender, add salt and monosodium glutamate, simmer over low heat to taste, pour into a soup bowl, sprinkle with pepper and chopped cilantro.

　　2, Red Plum Radish Balls

　　100 grams of radish, 50 grams of shiitake mushrooms, 50 grams of bamboo shoots, 1 egg. Wash the radish, cut into thin strips, blanch in boiling water, soak in cold water, drain and dry the water, place in a small bowl for later use; wash the shiitake mushrooms and bamboo shoots, cut into small pieces, mix with radish strips, add salt, monosodium glutamate, and sesame oil, mix well to make radish balls; beat the egg in a bowl, add cornstarch and flour, mix well and set aside; heat oil in a frying pan, fry the radish balls in the egg mixture, add tomato sauce and cook for a moment, then it is ready to eat.

　　3, Radish and Mutton Soup

　　300 grams of radish, 200 grams of mutton, 100 grams of peas. First, wash the mutton, cut into small pieces, place in a pot, add water to boil, remove the foam on the surface of the soup; wash the radish, cut into pieces, and put it in the mutton soup with the peas, boil over high heat, then reduce the heat to simmer, add salt and pepper as needed before serving, and add cilantro to the soup.

　　4, Radish Honey Juice

　　500 milliliters of radish juice, 50 milliliters of honey. Wash and peel the fresh radish, cut into strips and squeeze to extract juice, add honey (usually in a ratio of 10:1), stir well, and drink frequently.

　　5. Radish soup

　　One radish, 4 bowls of high-quality soup, a little coriander. Wash and peel the radish, and chop the coriander into small pieces. Add the radish pieces and an appropriate amount of high-quality soup to the pot, bring to a boil, then reduce to a low flame, and cook until the radish can be pierced with a chopstick. Season and turn off the heat before serving. Sprinkle with coriander before serving.

　　Before treating Overventilation Syndrome, it is necessary to explain clearly the connection between the symptoms and overventilation to the patient, relieve the patient's mental burden, and eliminate fear. Necessary medications such as Guaifenesin, bromides, and sedatives can be given. Teach patients to master the correct breathing method, which is abdominal breathing and slow breathing, to reduce or eliminate the tendency of overventilation by slowing down the breathing rate. Repeated breathing therapy can be used, and during acute attacks, face masks (or bags) can be used for repeated breathing therapy to increase the CO2 in the inhaled gas and alleviate symptoms.

　　1. Bag breathing: Use a 5-10L paper bag or plastic bag, place it over the mouth and nose, and seal it for breathing.

　　2. Mixed gas inhalation: 5% CO2, 35% O2, and nitrogen, balanced and inhaled.

　　3. Try calcium gluconate intravenous injection.

　　4. Relaxation therapy: Lie down, close your eyes, and alternate focusing your attention to relax part of your limbs, all your limbs, neck, face, head, and the whole body until you feel comfortable and relaxed. You can also listen to soothing music or combine relaxation therapy with breathing exercises.

　　5. Breathing exercises: Patients should relax their whole body, breathe evenly, and consciously slow down their breathing rate or hold their breath to reduce the exhalation of carbon dioxide, improve alkalosis, and alleviate symptoms.

　　6. Slow down the pace of life, work, and psychological stress.

　　7. Psychological treatment: Family and friends should focus on psychological counseling for patients, communicate actively with them, strive to find the triggers of their illness, and patiently conduct psychological guidance and comfort. Do not show negative emotions such as tension and anxiety in front of patients to avoid further aggravating their condition.

　　8. Drug treatment:

　　(1) Antianxiety drugs: Librium, Valium, Diazepam, Methyldiazepam, and Serax.

　　(2) Tricyclic antidepressants: Clomipramine.

　　(3) Adrenergic blockers such as Propranolol.

　　(4) Vitamin B.