Inhalation anesthetics of general anesthetics
Inhalation anesthetics (inhalation anaesthetics) is a volatile liquid or gas, the former such as ether, halothane, isoflurane, enflurane, the latter, such as nitrous oxide. ① halothane. Colorless flow of liquid, the quality of non-ignited, with chloroform-like smell and burning sweet. Anesthesia than ether strong, no irritation to the mucous membrane, induction time is short, does not cause excessive secretion, cough and laryngeal spasm and so on. Used as anesthesia and induced anesthetics. ② anesthesia ether. Colorless and clear volatile liquid, flammable, with a specific odor, soluble in water, soluble in alcohol, grease and so on. Ethylene steam and air mixed, the case of fire can explode. Animals inhaled ether, the first inhibition of the cerebral cortex, the induction period is longer. Suitable for middle and small animals anesthesia. Inhalation anesthesia, the need to control the depth of clinical anesthesia and to avoid the risk of excessive anesthesia, often anesthesia stage of the most obvious ether anesthesia as the representative of the inhalation anesthesia depth is divided into four, as follows: the first phase (pain period) Is from the beginning of anesthesia to the beginning of consciousness and feeling disappeared. The patient enters the analgesic state of anesthesia by a sobering consciousness and a feeling of disappearance. The state of analgesia was associated with inhibition of the activation of the cortex and reticular structure. The second period (excitement) refers to the beginning of the anesthesia period from the disappearance of consciousness and feeling to surgery. Patients with excitement and restlessness, irregular breathing, blood pressure instability and other subcortical depressive symptoms. The first and second periods are collectively referred to as anesthesia induction period. During the induction period, prone to laryngeal spasm or cardiac arrest and other anesthesia accident, should not do any surgery or surgical examination.
The third phase (surgical anesthesia) patients from excitement to quiet, breathing and blood pressure tends to smooth for the beginning of the current signs. With the increase in anesthesia depth, the subcortical center of the cortex from the "cortex - brain - brain - pons" from top to bottom gradually inhibited, the spinal cord was suppressed from the bottom up. Surgical anesthesia can be subdivided into four levels: general surgery in this period of the second and third anesthesia. In the depth of the fourth level of anesthesia, medullary life center is inhibited, the patient showed respiratory depression, hypoxia cyanosis, blood pressure, the doctor should immediately reduce or withdrawal, to avoid anesthesia accident. The fourth stage (medullary anesthesia) patients with respiratory arrest, blood pressure can not be measured. In case of medulla oblongata anesthesia, must be immediately discontinued, first aid, to maintain the respiratory and circulatory function, attention to vital signs, to full recovery. The above staging is a typical staging of ether anesthesia alone. It is a theoretical basis for the depth of anesthesia and can be used as a reference scale to measure the depth of anesthesia and play an important role in clinical anesthesia management. Now commonly used in clinical anesthesia methods to reduce the risk of anesthesia induction period. Due to the rapid application of compound anesthesia in the surgical anesthesia period, the above-mentioned typical anesthesia depth staging, especially the anesthesia induction period (the first and second term co-induction period) is no longer present in clinical anesthesia practice.
