Describe Preoperative Assessment in detail.

Purpose

Preoperative assessment is the evaluation of a patient before anaesthesia and surgery. Its aims are to assess fitness for the proposed procedure, identify and optimise co-existing disease, predict and plan for difficulties (airway, cardiovascular, aspiration), plan the anaesthetic technique and postoperative care, obtain informed consent, and allay anxiety. Good assessment reduces perioperative morbidity, cancellations and delays.

History

• The history covers the presenting surgical problem
• co-existing medical conditions (especially cardiovascular, respiratory, diabetes, renal, hepatic and neurological disease)
• previous anaesthetics and any problems (nausea, difficult intubation, prolonged recovery) and a family history of anaesthetic problems (e.g. Malignant hyperthermia, suxamethonium apnoea)
• a full drug history and allergies
• functional capacity (exercise tolerance). Smoking, alcohol, and, in women, pregnancy are recorded.

Examination

Examination focuses on the airway (mouth opening, Mallampati class, neck movement, thyromental distance, dentition — to predict difficult intubation), the cardiovascular and respiratory systems, and any relevant systems suggested by the history. Baseline vital signs, weight and height (BMI), and venous access are noted.

Investigations

Investigations are guided by the history, examination, the patient and the surgery — not ordered routinely. Common tests where indicated: full blood count (anaemia, infection), urea & electrolytes (renal disease, diuretics), blood glucose/HbA1c (diabetes), coagulation (liver disease, anticoagulants), ECG (cardiac disease, older patients), chest X-ray and echocardiography/pulmonary function in selected cases, and group and save/cross-match for procedures with blood-loss risk.

Risk Assessment & Optimisation

The assessment concludes with an estimate of perioperative risk (using the ASA physical status, functional capacity and the magnitude of surgery) and a plan to optimise modifiable problems (e.g. Controlling blood pressure or glycaemia, treating anaemia or infection, adjusting medications). High-risk patients are identified for enhanced monitoring, critical-care planning and senior involvement.

Airway Assessment

A structured airway assessment is a defining part of the anaesthetic pre-visit, because an unanticipated difficult airway is a major cause of anaesthetic harm. Alongside the Mallampati view, the anaesthetist assesses mouth opening (inter-incisor distance), thyromental distance, neck flexion and extension, jaw protrusion and the state of the dentition, and asks about previous difficult intubation, snoring or obstructive sleep apnoea, and conditions that distort the airway (rheumatoid arthritis, prior surgery or radiotherapy, tumours). No single test is reliable, so a combination is used to build an overall impression and, where difficulty is predicted, to plan an appropriate technique and equipment in advance.

Timing & the Pre-assessment Clinic

Ideally the assessment happens far enough ahead of surgery that problems can be corrected — in a pre-assessment clinic for elective cases — rather than being discovered on the day when cancellation is the only option. Early assessment allows anaemia to be treated, blood pressure or diabetes to be brought under control, medications to be adjusted, further tests or specialist opinions to be obtained, and the patient to be given clear fasting and medication instructions, all of which reduce last-minute cancellations and improve safety and efficiency.

Optimisation before surgery reduces perioperative morbidity most.

• Preop assessment: assess fitness, optimise disease, predict difficulty, plan technique, consent, reassure.
• History: co-existing disease, previous anaesthetics/family problems, drugs/allergies, functional capacity.
• Examination: airway (Mallampati, mouth opening, neck), CVS/RS, vitals, BMI, access.
• Investigations are indicated (by patient & surgery), not routine.
• Conclude with risk (ASA + functional capacity + surgery) and optimisation of modifiable problems.