I. Introduction: The so-called “hematemesis”, also known as “blood phobia”, refers to the phenomenon of syncope due to the sight of blood, which is a sudden stressful reaction that causes temporary derangement of neurophysiological functions after the sight of blood. The main manifestations are dizziness, nausea, dizziness, palpitations, followed by pallor, cold sweat, cold extremities, reduced blood pressure, weak pulse, and even sudden loss of consciousness. It is also referred to as Al’s syndrome or Aniel’s syndrome, which is a psychological reaction and mental disorder of excessive fear in a particular situation. When people develop a sense of fear that is incongruent with the actual danger in situations or occasions that should not normally cause fear, they may suffer from a phobic neurosis, or phobia for short. Fear is one of the most primitive human emotions, and unlike anxiety, fear is an adaptive response to a real threat. Anything objective that can pose a danger or threat to a person is capable of triggering fear. The three main types of phobias are place fear, social fear, and idiosyncratic fear. The idiophobic patient is not close to a specific situation or thing to fear, and once exposed to such a situation or face to face with such a thing, a severe sense of depression and fear will arise. Examples include agoraphobia, hydrophobia, and animal fear, which can produce fear even when there is no threat. Hematophobia is an idiosyncratic fear. Hemalgia is not an organic disease, and is the same phobia as the fear of seeing snakes and caterpillars, and the fear of meeting strangers and the fear of meeting the opposite sex, which is the same as the fear of socializing, and is not necessarily related to timidity. This syndrome is also different from motion sickness and seasickness, but somewhat similar to agoraphobia, which is a psychological problem. Although the cause of this disorder has not yet been clarified, this mental disorder is not the type of mental illness commonly known as “neurosis”. Except for the inability to see blood, people who suffer from blood sickness are no different from normal people. The disorder is most common in women and rarely has other symptoms or syndromes. It occurs in about 3-4% of the population. For everyone, the sight of blood can be a little bad, but for some people, it can be a big problem, according to the American journal Popular Science. According to a related study by Isaac Marks of the London College of Psychiatry, more than 30 percent of children are afraid of seeing blood, and the phenomenon is also prevalent among adults. The study also revealed that nearly 15% of adults faint when giving blood. Causal analysis: Fainting from blood is generally caused by an overactive vagal response, which is an evolved fear reflex. This response slows your heart rate and lowers your blood pressure, causing blood to flow to your legs. This means that not enough oxygenated blood enters your brain, causing you to feel dizzy and even faint. When people with phobias are confronted with the object they fear, their heart rate does not simply increase and their blood pressure rises, because these people initially experience an increase in heart rate and blood pressure followed by a dramatic drop, often accompanied by vomiting, dizziness and fainting. Indeed, 75% of people with hematemesis-injury phobia have a history of fainting in these situations. Blood fainting is a form of hysteria, that is, an overwhelming reaction of the consciousness and the body due to exposure to or the sight and smell of blood. The consciousness is characterized by panic, palpitations, and vertigo, while the physiological and somatic manifestations are increased blood pressure, increased heart rate, regurgitation, and limb weakness. Blood fainting actually originates from the conscious activity in the cerebral cortex. The brain sends out instructions to stimulate the secretion of relevant hormones to produce physiological and somatic reactions. In terms of hysteria, women are stronger than men, and children are stronger than adults. Therefore they are more susceptible to psychological cues. Psychologically, children carry the hysteria generated by their early fear experiences into adulthood, forming a subconscious, so that when they encounter blood, a frightening atmosphere is created and blood fainting occurs. In severe cases, the presence of hysterical thoughts in the mind even if the eyes are closed at the sight of blood will still cause blood fainting. People who experience blood fainting and intense blood fainting may experience some inconvenience in their daily lives. You can start with awareness and then a small amount of short exposure to reach a point where you are no longer afraid, as was often the case in the war years. Blood is always associated with events such as injury (natural or warlike assault) and death (severe blood loss), when it represents something horrible. Here the hysteria generated can come from their own experience, such as injuries bleeding, producing pain and therefore fear; can come from witnessing what they see, seeing others (or animals) bleeding a lot, their people pain and fear or even death; can come from the psychological implication, such as someone talking about bloodshed events, film and literature descriptions, speaking of very horrible, so that in their own brains also produce hysteria, the same kind of psychological horror. For example, if someone says that it is painful to have a child naturally, some women must ask for a C-section or even dare not have a child, when in fact they have not gone through a natural birth. Interestingly, the blood and injury phobia only shows its characteristic physiological reactions in the face of blood and injury stimuli, while the fear of other objects shows more typical “fight and flight” physiological reactions. This survival mechanism is good if you have to play dead in front of a predator, so we humans have evolved this survival mechanism. Also, if you are bleeding, a slower heart rate prevents excessive blood loss. But in most cases, especially in a critical situation, you know you have to stay awake and fainting at the sight of blood can be a big problem. There is a strong family component to the fear of blood-sickness and injury, with two-thirds of patients having immediate family members who also suffer from the same phobia. Whether this factor reflects genetic factors influencing the same family members to share common environmental experiences, the results are unclear. But the specific purpose that may have developed from this unique form of physiological response is that of inhibiting future episodes or alertness by the mechanism of blood-sickness fainting episodes. Generally speaking there is little relationship with genetic factors. Blood fainting arises later in life, as a result of subjective encounters, or experiences learned through the experience of others or through books. In particular, it is an indirect experience acquired before full judgment. This has already been mentioned above. For example, the birth of a child is not much blood-sickness phenomenon, is an example. This is also the case when you watch a horror movie and get scared when you encounter a similar situation. Third, treatment: Those who suffer from hematemesis will feel horror and nausea when they see blood in the lighter cases; in the heavier cases, they will lose consciousness. These problems may affect the patient’s work and life. However, hematemesis is not an incurable disease. Treatment of this disorder starts with eliminating fear, and the main way to overcome fear is cognitive-behavioral therapy. Psychotherapists usually let patients face the feared object or place directly, and eliminate the fear experience with exposure method, or use systematic desensitization method (such as seeing blood repeatedly and gradually from weak to strong under the guidance of a psychologist) to gradually reduce the sensitivity to the feared object or situation, so that patients can gradually face the feared object with ease and overcome their fear. The more one sees or thinks of blood, the less such phobias will occur, says Alan Maniewicz, a psychiatrist at New York’s Weill Cornell Medical Center. That could explain why tried-and-true surgeons are comfortable with blood. This “systematic exposure” is a common approach to treating specific phobias. And it saves lives: the sick person will overcome the phobia and be willing to accept treatment. Self-confidence training by identifying the root cause of the fear can also have an objective effect. Anti-anxiety drugs as a complementary or acute measures, can effectively prevent or stop the physiological reflections of fear, such as blushing, heartbeat, sweating, shaking, etc., but should follow medical advice, sparingly or carefully used to avoid the formation of dependence. Fourth, first aid treatment: the onset of hematemesis rescue methods: hematemesis itself is a vasovagal syncope, such as syncope induced by pain, tension, fear, shock and various trauma. Because these factors are common causes of the occurrence of stress. General syncope is nothing more than a temporary loss of consciousness, in a state of shallow coma, with physiological reflexes present and stable vital signs, so there is no need to panic. The patient should be placed flat on his back, moved to a safe environment with appropriate temperature, unbuttoned the neck, removed if there are dentures, removed foreign bodies or sputum in the mouth, oxygen at low flow rate, tapped the patient’s shoulder, and called the patient gently, usually a few minutes to wake up naturally. It is recommended not to feed the patient with water to prevent choking and coughing, which may cause unnecessary trouble. Rest for 10-15 minutes, generally can recover, if necessary, need to give drug resuscitation treatment. Commonly used drug rescue methods: 1, keep the airway open, give oxygen; 2, in an emergency, establish intravenous access, available 5% glucose injection; 3, naloxone 0.4 – 0.8mg dilution after sedation; 4, rapid determination of blood sugar, BS <4mmol/L, intravenous injection of 50% GS40 - 60ml; 5, high intracranial pressure to give 20% mannitol 250ml rapid 6, close observation of vital signs, electrocardiographic monitoring, hospitalization and observation for those with confusion; 7, symptomatic treatment: low blood pressure, shallow and fast respiration, add dobutamine; respiratory failure, give nikethamide, lopressor; tachycardia, static lidocaine; if there are convulsions, static calcium gluconate, etc.