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Thursday, March 31, 2011


The American  Society of Anaesthesiology classification of  physical status(ASA) is still  used  widely as a scoring system to assess the fitness of  patients subjected to anaesthesia and surgery. The scoring  system was devised to assess the physical status of patients before anaesthesia is planned and was applied uniformly for all patients.The grading system was  useful for record  keeping and for statistical analysis of patients' health status who were scheduled for  administration of anaesthesia.This  grading system is not indicated  for prediction of operative risk.

The evolution of ASA  grading  system[1]
In 1940-41, ASA asked a committee of three physicians (Meyer Saklad, M.D., Emery Rovenstine, M.D., and Ivan Taylor, M.D.) to study, examine, experiment and devise a system for the collection and tabulation of statistical data in anaesthesia which could be applicable under any circumstances.[1] They were  given the  task to devise a grading system to assess the  operative risk , but  after  detailed studies  research and discussion they  stated that "In attempting to standardize and define what has heretofore been considered 'Operative Risk', it was found that the term ... could not be used. It was felt that for the purposes of  the anesthesia record and for any future evaluation of anesthetic agents or surgical procedures, it would be best to classify and grade the patient in relation to his physical status only."They described a six-point scale, ranging from a healthy patient (class 1) to one with an extreme systemic disorder that is an imminent threat to life (class 4). The first four points of their scale roughly correspond to today's ASA classes 1-4, which were first published in 1963.[2] The original authors included two classes that encompassed emergencies which otherwise would have been coded in either the first two classes (class 5) or the second two (class 6).Two modifications were made in 1963 when the new classification is proposed ,the previous classes 5 and 6 were removed and a new class 5 was added for moribund patients not expected to survive 24 hours,with or without surgery.In addition emergency cases were  designated  by the letter 'E'.[3] The sixth class is a recent addition for declared brain dead organ donors. The six ASA  classes  for evaluation of physical status are 

An immediate  green flag: Normal healthy patients  are  coming under this group.Ptients can walk one flight of stairs or two level city blocks without distress.No clinical co morbidity , no significant  past or present medical or surgical history.
Patients have mild to moderate systemic disease which is well controlled.Patients are able to walk up one flight of stairs or two level city blocks,but with  moderate levels of exertional distress. History of well-controlled disease states including non-insulin dependent diabetes,Patients with anginal symptoms less than once a week,High blood pressure  treated with a single type of medicine,[4],or asthma controlled by inhalers. ASA III
Patients with severe systemic disease that limits activity, but is not incapacitating.Angina symptoms more than once a week,Taking more than one blood pressure tablet Having complications of diabetes such as kidney failure or poor circulation,Asthma requiring frequent hospital admissions,Respiratory disease [COPD / COAD] causing breathlessness climbing a single flight of stairs,Someone with a raised creatinine of less than 200 micro mol/L,without dehydration, are all examples.[5]
A Patient with severe systemic disease that is a constant threat to life:Advanced liver disease, severe COPD, ARDS,  History of unstable angina pectoris, myocardial infarction or cerebrovascular accident within the last six months, severe congestive heart failure, , and uncontrolled diabetes, hypertension, epilepsy,etc.
A moribund patient not expected to survive 24 hours with  or without surgery, eg;Severe  gangrenous intestine in septic shock or terminally ill patients.
A brain dead donor  for organ harvestation.
The prefix 'E' is added to emergency operation of any class eg; ASA I E, for  emergency  caesarean section in an ASA I patient.

The inconsistency and inadequacy of ASA grading system has been questioned for many years. The major drawbacks of  this grading system are
  • Inconsistency of grading between anesthetists.[6],Research by Haynes, S. R. and Lawler, P. G. P, showed that  so much variation was observed between individual anaesthetist's assessments when describing common clinical problems and that the ASA grade alone cannot be considered to satisfactorily describe the physical status of a patient.
  • Age; is not  considered as an influencing factor,extremes of age like elderly patients and neonates may have poor tolerance to surgery and anaesthesia in the absence of systemic illness and cannot be considered as ASA 1 patients.
  • The grading system is not well suited for assesing physical status of special  clinical conditions like burns,trauma and metabolic disorders
  • No grade was available to describe moderate systemic illness.
  • The ASA Grading System shows poor interrater reliability in pediatric practice[7]
Here comes the importance of revising the ASA physical status system.An attempt was made by  Tomoaki Higashizawa M.D., Ph.D. and Yoshihisa Koga M.D.,who revised the score and introduced a 7 graded scoring system.This was done by modification of the original ASA grading system as below.[8] The authors claim reevaluation of ASA physical status (7-grade) can provide a better grading outcome for predicting the incidence of intra- and postoperative complications in surgical patients compared with the conventional ASA's.

With 2 subclasses 1a 1b,2a,2b this classification seems to be appropriate to fill up the gap between the severity of systemic illness  but difficult to apply for routine use because of its complex nature.We expect that a revision of ASA  grading system will be implemented soon by ASA.

Many anaesthetists are concerned more with the morbidity and mortality of associated risk conditions, The physical status evaluation alone was not useful for risk stratification and many other grading systems were devised to evaluate the perioperative risk.eg; E-PASS and POSSUM score.
1)Saklad M. Grading of patients for surgical procedures. Anesthesiology 1941; 2:281-4.(by courtesy of WIKIPEDIA)
2) Little JP (1995). "Consistency of ASA grading". Anaesthesia 50 (7): 658–9. pubmed.
3)New classification of physical status. Anesthesiology 1963; 24:111
4)Margaret J. Fehrenbach, RDH, MS, from the American Society of Anesthesiologists, Medical Emergencies in the Dental Office (Malamed, Mosby, 2008), 
5)http://www.nhfd.co.uk/003/hipfractureR.nsf/ (National hip fracture database)
6)Haynes, S. R. and Lawler, P. G. P. (1995), An assessment of the consistency of ASA physical status classification allocation. Anaesthesia, 50: 195–199.
7)Aplin S, Baines D,Lima, Use of the ASA physical status grading system in pediatric practice.,Pediatric Anaesthesia,2007 Mar;17(3):216-22.
8)T. Higashizawa & Y. Koga : Modified ASA Physical Status (7 grades) May Be More Practical In Recent Use For Preoperative Risk Assessment . The Internet Journal of Anesthesiology. 2007 Volume 15 Number 1.