Preoperative Assessment Guidelines

Preoperative Assessment

• Reduce patient surgical and anesthetic perioperative morbidity or mortality, returning them to desired function as quickly as possible
• History and physical examination crucial, focusing on cardiac and pulmonary risk factors, and functional capacity
• Laboratory investigations only when indicated by patient's medical status, drug therapy, or procedure. Routine testing is not beneficial
• Comorbid patients should be optimized for the procedure
• Consultations with appropriate medical specialists necessary to improve patient health
• Pre-anesthetic assessment performed by anaesthesiologist, but if not possible, a mechanism for conveying findings is necessary
• Assessment performed at an appropriate time before scheduled surgery
• Day care patients also require appropriate pre-anesthetic timing
• Preoperative admission indicated for patients requiring further evaluation or intervention before a major surgery
• Admission not necessary just for pre-operative investigations, which can be performed as an outpatient
• Assessment delivered via personal interview in the ward, operating theatre (induction room) or a pre-anaesthetic clinic. Alternatively, using pre-set questionnaires with trained nursing or paramedical staff under an anaesthetist's supervision.
• Input from other medical specialties might be needed but only the anaesthesiologist can determine patient fitness for anesthesia
• In emergency surgery, anaesthesiologist still responsible for assessment, even if consultation isn't possible. If delaying surgery is problematic due to increased anesthetic risk, documentation required
• History must include past and current medical history, past surgical history, family history of anaesthetic complications, social history, allergy history, current drug therapy, previous anesthetic complications

History Considerations for Children

• Birth history, focusing on prematurity and perinatal complications
• Congenital chromosomal or anatomic malformations
• Recent infections, especially respiratory tract infections

History Considerations in General

• Complete review of systems for undiagnosed or inadequately controlled chronic disease
• Cardiovascular and respiratory systems most critical in determining anesthetic fitness

Physical Examination

• General assessment (weight, height, temperature, vital signs)
• Airway assessment
• Systemic examination
• Site of regional block (spine, deformities)

Airway Assessment

• Airway maintenance fundamental to safe anesthetic practice
• Identifying patients with potential airway management issues during the pre-operative assessment is vital

Patients with Potential Difficult Airway

• Obesity
• Pregnancy (especially pre-eclampsia)
• Anatomical abnormalities (micrognathia/macrognathia, macroglossia, congenital syndromes like Pierre-Robin or Treacher-Collins, burn contractures involving head and neck)
• Evidence of upper airway obstruction (tumors, edema, goiter, epiglottitis, maxillofacial trauma, airway burns, cervical spine problems, subluxation, rheumatoid arthritis, ankylosing spondylitis)
• History of radiotherapy (to head and neck, specifically oral cavity)
• History of difficult intubation during previous anesthetics (examining records for the cause)
• Predictors (obesity, buckteeth, large tongue, reduced jaw movement, receding chin, neck swelling, tracheal deviation, respiratory pattern)

Airway Evaluation

• Oropharyngeal visualization via Mallampati Score
• Sitting position, protruding tongue, without saying "AHH"
• Physical examination (anatomic variations, mouth opening (less than 3 finger widths), dentition)
• Neck (hyoid-mental distance, thyro-mental distance, cervical spine mobility)
• Post-tracheostomy considerations
• Assessment Methods: Mallampati Score Classification, Wilson Risk Sum Score, Cormack & Lehane Score Classification

Risk Factors for Difficult Intubation (Wilson's Risk Sum)

• Weight (<90kg, 90-110kg, >110kg)
• Head and neck movement (>90 degrees, about 90 degrees, <90 degrees)
• Jaw movement (IG ≥ 5cm, Slux > 0; IG < 5cm, Slux=0; IG < 5cm, Slux < 0)
• Receding mandible (normal, moderate, severe)
• Buck Teeth (normal, moderate, severe)

Risk Factors Related to Difficult Intubation

• Thyromental distance <6.5cm, Sternomental distance <12.5cm, Mallampati class 3 or 4. (80% likelihood)
• Cormack and Lehane Classification (Grades I-IV)

OSA (Obstructive Sleep Apnea)

• Conditions associated with OSA (obesity, thick/fat neck, micrognathia/retrognathia, large tongue, large tonsils, nasal obstruction)
• OSA severity (mild, moderate, severe, clinically or through sleep studies (polysomnography))
• Mild (obese, snoring, occasional daytime somnolence)
• Severe (morbidly obese, definite apneas/arousals, cyanotic spells, daytime somnolence)
• Moderate (between mild and severe)

Perioperative Risk

• Function of preoperative medical condition, surgical procedure invasiveness, and administered anesthetic type
• ASA classification system used (grades 1-6) for grading physical condition

NYHA Classification System

• Grading physical activity limitations used for cardiovascular disease (Classes I-IV)

Risk Stratification

• Goldman's Multifactorial Cardiac Risk Index
• Lee's Revised Cardiac Risk Index
• Variables, points and scores used to calculate risk

Investigations

• Clinical history and physical examination are the primary methods for disease screening; routine laboratory tests are not indicated for apparently healthy patients.

Recommended Pre-anesthetic Investigations

• Electrocardiogram (age >50, cardiovascular disease, DM, renal disease)
• Chest X-ray (age >60, significant respiratory or cardiovascular disease)
• Full blood count (age >60, Clinical anemia, haematological disease)
• Renal profile (age >60, renal disease, liver disease, DM)
• Coagulation profile (hematological disease, liver disease, anticoagulation, intra-thoracic/intracranial procedures)
• Random blood sugar (age >60, diabetes mellitus, liver dysfunction)
• Liver function tests (hepatobiliary disease)
• Procedures with blood loss >15%
• Blood loss > 15%

Drug History

• Obtain medication history including morning of surgery
• Monoamine oxidase inhibitors should be withdrawn 2-3 weeks before surgery
• Oral contraceptive pills should be stopped at least 6 weeks before elective surgery
• Herbal medications need to be stopped 2 weeks before anesthesia

Pulmonary Risk

• Careful history and physical examination crucial for pulmonary assessment
• Spiro-metry is not usually part of the routine assessment
• When uncertain about lung impairment, spirometry helpful
• Postoperative pulmonary complications (PPCs occur 5%-10% patients in major non-cardiac surgery and in 22% of high risk patients. Within a week of surgery, one in 4 deaths linked to PPC

Preoperative Fasting

• Pulmonary aspiration possible with gastric contents (even 30-40ml)
• Factors leading to this (inadequate anesthesia, pregnancy, obesity/difficult airway/emergency surgery).
• Full stomach and altered GI motility can impact aspiration risk

Acid Aspiration Prophylaxis

• Routine in pregnant women, and those with esophageal reflux
• Proton-pump inhibitors, H2-antagonists, and antacids useful

Premedication Considerations

• Benzodiazepines, opioids, anticholinergic drugs, and H2 blockers (avoided in extreme age patients, upper airway obstruction, severe pulmonary & heart disease & unstable patients)

Consent Considerations

• Confirmation with patient/guardian
• Details of procedure
• Procedure consent requested

Documentation Considerations

• Written summary of the assessment and any arrangements needed

Pre-operative, Intra-operative, Post-operative Assessment Summary (Pneumonic)

• Pre-Op— Introduction & role, history, examination, meds/allergies, investigations, consents, optimise patient condition, premedication, transfer
• Intra-Op—Haemodynamic stability, fluid management, normocarbia, normoglycemia, normothermia, normoxia, pain control
• Post-Op—Airway, breathing, circulation, drugs, disability, DVT prophylaxis , after

References

• Several references provided covering different aspects of preoperative assessment, guidelines, and recommendations noted.

This quiz covers essential components and best practices for preoperative assessment to minimize surgical and anesthetic risks. Key factors include patient history, physical examinations, and necessary consultations. Understanding these protocols is vital for ensuring patient safety and optimizing health before surgery.