|
The ASA physical status classification system is a system for assessing the fitness of cases before surgery. In 1963 the American Society of Anesthesiologists (ASA) adopted the five-category physical status classification system; a sixth category was later added. These are: #Healthy person. #Mild systemic disease. #Severe systemic disease. #Severe systemic disease that is a constant threat to life. #A moribund person who is not expected to survive without the operation. #A declared brain-dead person whose organs are being removed for donor purposes. If the surgery is an emergency, the physical status classification is followed by “E” (for emergency) for example “3E”. Class 5 is usually an emergency and is therefore usually "5E". The class "6E" does not exist and is simply recorded as class "6", as all organ retrieval in brain-dead patients is done urgently. The original definition of emergency in 1940, when ASA classification was first designed, was "a surgical procedure which, in the surgeon's opinion, should be performed without delay." This gives an opportunity for a surgeon to manipulate the schedule of elective surgery cases for personal convenience. An emergency is therefore now defined as existing when delay in treatment would significantly increase the threat to the patient's life or body part.〔ASA Relative Value Guide 2002, American Society of Anesthesiologists, page xii, Code 99140.〕 With this definition, severe pain due to broken bones, ureteric stone or parturition (giving birth) is not an emergency. ==Limitations and proposed modifications== These definitions appear in each annual edition of the ASA Relative Value Guide. There is no additional information that can be helpful to further define these categories.〔(【引用サイトリンク】title=ASA Physical Status Classification System )〕 It is logical to expect a missing class between ASA 2 and ASA 3 for a systemic disease which is neither mild nor severe, but is of moderate nature. It is also not clear what will be the ASA classification of a case who is suffering simultaneously from two, three or more systemic diseases (which might be of different severity). An example of an ASA status classification system is that used by dental professionals.〔Fehrenbach, Margaret, ASA Physical Status Classification System for Dental Professionals at http://www.dhed.net/ASA_Physical_Status_Classification_SYSTEM.html〕 Many include the 'functional limitation' or 'anxiety' to determine classification which is not mentioned in the actual definition but may prove to be beneficial when dealing with certain complex cases. Often different anesthesia providers assign different grades to the same case. The word 'systemic' in this classification creates a lot of confusion. For example, heart attack (myocardial infarction), though grave, is a 'local' disease and is not a 'systemic' disease, so a recent (or old) heart attack, in the absence of any other systemic disease, does not truly fit in any category of the ASA classification, yet has poor post-surgery survival rates. Similarly cirrhosis of the liver, COPD, severe asthma, peri-nephric abscess, badly infected wounds, intestinal perforation, skull fracture etc. are not systemic diseases. These, and other severe heart, liver, lung, intestinal or kidney diseases, although they greatly affect physical status and risk for poor outcomes, cannot be labelled as “systemic disease” (which means a generalized disorder of the whole body like hypertension or diabetes mellitus). Local diseases can also change physical status but has not been mentioned in ASA classification. This classification system assumes that age has no relation to physical fitness, which is not true. Neonates and the elderly, even in the absence of any systemic disease, tolerate otherwise similar anesthetics poorly in comparison to young adults. Similarly this classification ignores those with malignancy (cancer). This classification system could not be improved to a more elaborated and scientific form, probably because it is often used for cost reimbursement. Although more complex scoring systems like APACHE II exist, they are time-consuming to calculate, and do not have the same utility for ease of communication between surgeons, anesthesiologists, and insurers as well as dental professionals providing local and general anesthesia. Some anesthesiologists now propose that like an 'E' modifier for emergency, a 'P' modifier for pregnancy should be added to the ASA score. Also, the ASA classification does not describe the general health status when excluding the condition that indicates the surgery. In fact, there are hospitals (e.g. Uppsala University Hospital) that do exclude the condition indicating the surgery. Thus, in such hospitals, ''ASA 1'' may still refer to a severe medical emergency, such as for example a moribund person due to a traumatic aortic rupture (which indicates the surgery) but otherwise being healthy. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「ASA physical status classification system」の詳細全文を読む スポンサード リンク
|