1. Aishah
Awatif
Haziq
Pre-operative evaluation and preparation (prior to procedure under general anesthesia)

2. Introduction Anaesthesia = absence of all sensation
Analgesia = absence of pain
General anaesthesia = a state where all sensation is lost and the patient is rendered unconscious by drugs.
GA should be performed by qualified anasthetists in a hospital setting with access to appropriate medical support.

3. Assessment of risk
Patient should be made as fit as possible for the operation.
The anticipated benefit should outweigh the anesthetic and surgical risks involved.
Overall mortality rate ≈ 1 in
Surgical mortality ≈ 1 in 1000

4. Factors contribute to this mortality:
Poor preoperative assessment
Inadequate supervision and monitoring in the intraoperative period
Inadequate postoperative care

6. Preoperative assessment and premedication

7. History Past medical history: Asthma Diabetes Tuberculosis Seizures
Chronic organ dysfunction
HIV infection
Drug allergy
DVT
Post-operative nausea and vomiting

8. Drug history Drug interactions
Anticoagulant might be contraindicated to spinal, epidural or other regional techniques
Anticonvulsants might increase the requirements for anasthetic agents, enflurane should be avoided as it might precipitate seizures
Beta-blockers – negative ionotropic effect – hypotension
Corticosteroids – extra cover might be needed
Diuretics – might have hypokalaemia
Insulin – careful monitoring of plasma glucose

9. Social history
Ceasing smoking 12h before surgery can improve the oxygen carrying capacity of the blood.
Excessive alcohol – hepatic and cardiac damage

10. Family history Hereditary traits: Haemophilia Porphyria
Cholinesterase abnormalities – prolongation of muscle relaxants such as suxamethonium

11. Physical examination Full physical examination
Especially the upper airway including the teeth and extent of mouth opening and flexibility of the neck – to assess the ease of tracheal tubing

12. Per-op investigation of elective patients
Indications of preoperative investigations
Full blood count
anaemia
females post menarche
cardiopulmonary disease
possible haematological pathology, e.g.
haemoglobinopathies
likelihood of significant intraoperative blood loss
history of anticoagulants
chronic diseases such as rheumatoid disease

13. Urea and electrolyte concentrations
Clotting screen
liver disease
anticoagulant drugs or a history of bleeding or
bruising
kidney disease
major surgery
Urea and electrolyte concentrations
major surgery >40 years
diabetes mellitis
digoxin, diuretics, corticosteroids, lithium
history of diarrhoea and vomiting

14. Liver function tests: these will be carried out when there ECG
is any suspicion of liver disease
ECG
>40 years asymptomatic male or >50 years asymptomatic female
history of myocardial infarction or other heart or vascular disease
<40 years with risk factors e.g. hyperlipidaemia, diabetes mellitus, smoking, obesity, hypertension and cardiac medication
Chest radiography
breathlessness on mild exertion
suspected malignancy, tuberculosis or chest infection
thoracic surgery

15. Pre-op therapy
Pt with respiratory disease – physiotherapy or bronchodilator therapy
Infective endocarditis – prophylactic antibiotic
Hypertension – adjustment of drug therapy to obtain optimal control (diastolic pressure below 110 mmHg)

16. Postponement of surgery
Pt with acute upper resp tract infection
Cardiac/endocrine diseases that are not yet under optimal control
Elective surgery should not be undertaken unless:
Pt has fasted for 6h for solid food, Infant formula or other milk
4h for breast milk
2h for clear non-particulate and non-carbonated fluids

17. Premedication benzodiazepines – anxiolysis, anterograde amnesia
Anticholinergic drug – reduce excessive secretions in the airway
Antiemetic
Antihistamine
Metoclopramide - enhance gastric emptying
Sodium citrate, H2 blockers, proton pump inhibitor – reduce gastric acidity

18. Preparation for anesthesia