Preanaesthesia Assessment

Vijaya Patil

The evaluation of patients before surgery
is a component of anaesthesia practice that must be performed to ensure the safe delivery of anaesthesia for every patient as well as answering patient’s queries about anaesthesia and thus allaying patient’s anxiety. Assessment of anaesthetic risks associated with the patient’s medical conditions, therapies, alternative treatments, surgical and other procedures, and of options for anaesthetic techniques is an essential component of basic anaesthetic practice. It also serves a purpose of educating patients about issues such as: NBM requirements, medications to be taken on the morning of surgery, and differences in anaesthesia options. How an anaesthesia group performs this evaluation is variable with the structure of preoperative clinics in hospitals across the country being quite variable. In India nature of preoperative evaluation varies between institutional practice and private nursing home practice. However, the major question that anaesthesiologists must ask when approaching this area of practice is: ‘‘Can a system for preoperative evaluation that uses the expertise of anaesthesiologists, surgeons, and physicians to deliver high quality, cost conscious, and efficient patient preparation for surgery be developed’’?

Definition of Preanaesthesia Evaluation
The literature does not provide a standard definition for preanaesthesia evaluation. Generally preanaesthesia evaluation is defined as the process of clinical assessment that precedes the delivery of anaesthesia care for surgery and for nonsurgical procedures. The preanaesthesia evaluation is the responsibility of the anaesthesiologist. It consists of the consideration of information from multiple sources that may include the patient’s medical records, interview, physical examination, and findings from medical tests and evaluations. As part of the preanaesthesia evaluation process, the anaesthesiologist may choose to consult with other healthcare professionals to obtain information or services that are relevant to perioperative anaesthetic care. Preoperative tests, as a component of the preanaesthesia evaluation, may be indicated for various purposes, including but not limited to (a) discovery or identification of a disease or disorder that may affect perioperative anaesthetic care, (b) verification or assessment of an already known disease, disorder, medical or alternative therapy that may affect perioperative anaesthetic care, and (c) formulation of specific plans and alternatives for perioperative anaesthetic care. The assessments made in the process of a preanaesthesia evaluation may be used to educate the patient, organize resources for perioperative care, and formulate plans for intraoperative care, postoperative recovery, and perioperative pain management.
Kitts has identified three primary goals of preoperative assessment1:
1. Acquiring the pertinent medical information, consultations, and laboratory testing necessary to assess perioperative risk.
2. Optimizing of the patient’s medical condition and developing an appropriate perioperative care plan.
3. Educating the patient about choices of anaesthesia, intraoperative care, and postoperative management to reduce preoperative anxiety

Timing of preanaesthesia evaluation
In a survey conducted by ASA Practice Advisory for Preanaesthesia Evaluation the majority of consultants and ASA members agreed that, for high surgical invasiveness, the initial assessment of pertinent medical records should be done prior to the day of surgery by anaesthesia staff. For medium and low surgical invasiveness, however the majority of members indicated that the initial assessment of pertinent medical records may be done on or before the day of surgery.2

Interview
The preoperative interview or history taking is the anaesthetists first introduction to patient. This is the most efficient and productive of the three basic techniques used in preoperative assessment. The object of interview is to detect unrecognized or subclinical disease that could increase perioperative risk. The preoperative history should focus on the indication surgical procedure, allergies, known medical problems, major traumas in past and current medications.

Components of physical examination
A complete physical examination should include weight and height, main vital signs like blood pressure, pulse and respiratory rate. A majority of consultants and the ASA members agreed that, at a minimum, a preanaesthesia physical examination should include an airway exam, a pulmonary examination to include auscultation of the lungs, and a cardiovascular examination.

Role of routine Preoperative Testing
The current literature is not sufficiently rigorous to permit an unambiguous assessment of the clinical benefits or harms of routine preoperative tests. The evidence suggests that 60-70% of preoperative testing is unnecessary if a proper history and physical examination are done.3,4 A Report by the American Society of Anaesthesiologists Task Force on Preanaesthesia Evaluation suggests that preoperative tests should not be ordered routinely as such tests do not make an important contribution to the process of perioperative assessment and management of the patient by the anaesthesiologist. Preoperative tests may be ordered, required, or performed on a selective basis for purposes of guiding or optimizing perioperative management. The indications for such testing should be documented and based on information obtained from medical records, patient interview, physical examination, and type and invasiveness of the planned procedure.
Acceptability of previously performed tests
X-ray chest and ECG can be acceptable if performed within last 6 months and there has been no change in patient's medical condition since then. However may be needed to repeat if patient has significantly worsened in the intervening period. Blood tests done within 6 weeks can be accepted if patient's condition has remained same.
Preoperative risk assessment
Nowadays anaesthesia is safer than before as shown in a review of more than 100,000 procedures under GA and spinal anaesthesia where patient and surgical riask fectors were major determinants of outcome.5 The American Society of Anaesthesiologists (ASA) classification was the first systematic attempt to stratify the risk for patients undergoing anaesthesia. This classification refers to mortality based on the general clinical impression of the severity of the underlying systemic disease

Type of anaesthesia and outcome Results of meta-analysis including 141 trials that included 9559 patients showed that epidural or spinal anaesthesia reduced mortality, risk of myocardial infarction, transfusion requirements, incidence of post operative pulmonary complications and respiratory depression compared to GA.6 Epidural anaesthesia also reduced risk of venous thromboembolism compared to GA.7 Class I no risk factors Class II 1-2 risk factors Class III > 2 risk factors Class I - patients need no further testing or therapy Class II - require perioperative beta blockade Class III - patients need an echocardiography, further testing if needed, and appropriate therapy, especially if they are about to undergo intermediate or high risk surgery.

Perioperative fasting policies
Restricted intake of food and oral fluids before surgery and GA has for long time been judged vital to reduce the risk of regurgitation of gastric contents and aspiration. However preoperative fasting can impair nutrition and hydration especially when surgery gets postponed frequently due to various reasons. Several reviews have suggested that an overly long fasting periods (traditionally overnight) might be unnecessary or even detrimental to patient.16 A number of societies have published new or revised guidelines dealing with preoperative fasting. The most comprehensive report published by ASA17 recommends that adults should have no clear fluids for atleast 2 hours, and should take their last light meal at least 6 hours before GA, regional anaesthesia or sedation. The routine use of gastrointestinal stimulants to decrease the risk of pulmonary aspiration in healthy patients is discouraged. The same guidelines recommend a 6 hour fats for non human milk or infant formulae for neonates and infants and a less strict 4 hour policy for breastmilk feeding.

References
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2. Practice Advisory for Preanesthesia Evaluation: A Report by the American Society of Anesthesiologists Task Force on Preanesthesia Evaluation. Anesthesiology 2002; 96 : 485-96.
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12. Eagle KA, Berger PB, Calkins H, et al. ACC/AHA guideline update for perioperative cardiovascular evaluation for noncardiac surgery-executive summary. A report of the American College of Cardiology/American Heart Association Task Force on practice guidelines (Committee to update 1996 guidelines on perioperative cardiovascular evaluation for noncardiac surgery). Circulation 2002; 105 : 1257-67.
13. ACP- American College of Physicians. Guidelines for assessing and managing the perioperative risk from coronary artery disease associated with major noncardiac surgery. Ann Intern Med 1997; 127 : 309-12.
14. Fleischmann KE, Goldman L, Young B, Lee TH. Association between cardiac and noncardiac complications in patients undergoing noncardiac surgery: outcomes and effects on length of stay. Am J Med 2003; 115 : 515-20.
15. American College of Physicians. Preoperative pulmonary function testing. Ann Intern Med 1990; 112 : 793-4.
16. Kallar SK, Everett LL. Potential risks and preventive measures for pulmonary aspiration: new concepts in preoperative fasting guidelines. Anaesth Analg 1993; 77 : 171-82.
17. American Society of Anaesthesiologists task force on preoperative fasting. Practice guidelines for preoperative fasting and the use of pharmacologic agents to reduce the risk of pulmonary aspiration: application to healthy patients undergoing elective procedures. Anesthesiology 1999; 90 : 896-905.