History, examination and relevant investigations

• Such an assessment has four goals:-1.to acquire the relevant information about the

patient's state2.to educate the patient3.to diminish anxiety 4.to obtain informed consent from the patient

for the proposed procedure.

• The assessment should determine:-1. the nature and extent of the relevant surgical

pathology2. the nature and extent of any disease which might

affect the conduct of the operation and postoperative course

3. Any specific problems that might affect choice of anaesthesia and postoperative care

History

• Present illness (including age, sex, complaint, planned procedure, elective/ emergency?)

• Past Medical History:-1.List of medical problems2.Medications, allergies, drug history,

recreational drug use3.Past surgeries, type of anesthetic used,

anesthetic related problems

• Family History:-1.Any anesthetic related problems• Social History:-1.Smoking, alcohol, STDs, HIV etc

Systemmic Review

• General:-1.Vital signs2.Exercise tolerance, weakness, fatigue, fever,

weight changes, frequent headaches• Skin:-1.Rashes, sores, lesions• Eyes:-1.Double vision, blurring, glaucoma, cataract

Ear:-•Tinnitus, vertigo, dischargeMouth:-•Bleeding gums, dentures, loose teethCardiovascular system:-•HPT, MI, CCF, RF, murmurs, angina, palpitations•PND, peripheral oedema

• Respiratory system:-1.Cough, sputum, haemoptysis, asthma, TB• GI:-1.Hiatus hernia, GERD, diarrhoea, constipation,

haematemesis, maleana, jaundice, hepatitis• Urinary system:-1.Frequency, urgency, nocturia, dysuria,

haematuria, incontinence

• Female:-1. LMP, likelihood of current pregnancy• Neurologic:-1. Claudication, thrombophlebitis, seizure, stroke• Haematologic:-1. Anaemia, past transfusions• Endocrine:-1. Thyroid abnormalities, diabetes

• Psychiatric illness• Prosthetics

• The most common general assessment of fitness used by anaesthetists is the American Society of Anesthesiologists' (ASA) Physical Status Classification

ASA Classification

1. A normal healthy patient2. A patient with mild systemic disease3. A patient with severe systemic disease4. A patient with severe systemic disease that is a

constant threat to life5. A moribund patient who is not expected to

survive without the operation (E)6. A declared brain-dead patient whose organs are

being removed for donor purposes.

Other Points to Consider Other than the ASA Classification

• To predict:-• operative risk• age and obesity of the patient• the nature and severity of the operative procedure• selection of anesthetic techniques• the competency of the surgical team (surgeon,

anesthesia providers and assisting staff)• duration of surgery or anesthesia• availability of equipment, medicine, blood, implants

and especially the level of post-operative care etc.

APACHE II ("Acute Physiology and Chronic Health Evaluation II")

• is a severity of disease classification system (Knaus et al., 1985)

• A general measure of disease severity based on – Current physiologic measurements – Age – Previous health condition.

• Scores range from 0-71 • Increasing score associated with an increasing

risk of hospital death.

• APACHE II score = (acute physiology score) + (age points) + (chronic health points) Acute Physiology Score

• 1= Rectal temp (C) • 2 = Mean arterial pressure (mmHg) • 3 = Heart rate (bpm) • 4 = Respiratory rate (bpm) • 5 = Oxygen delivery (ml/min) • 6 = PO2 (mmHg) • 7 = arterial pH • 8 = Serum sodium (mmol/l) • 9 = Serum potassium (mmol/l) • 10 = Serum creatinine (mg/dl) • 11 = Haematocrit (%) • 12 = White cell count (103/ml)

Age Points<44 045-54 255-64 365-74 5>75 6

History of severe organ insufficiency Points

Non-operative patients 5

Emergency postoperative patients 5

Elective postoperative patients 2

Investigations

Before Requesting Investigations

1. Does the investigation detect conditions not found on history taking and physical examination which will affect perioperative management?

2. Do the investigations give a useful baseline for comparison in the postoperative phase?

3. What are the specificities and sensitivities of the investigation?

4. Are there medicolegal considerations for performing the investigations?

5. If the result is not available, will the operation be affected?

• A full blood count (FBC) is generally requested to detect anaemia, which may place the individual at risk from a general anaesthetic

• Coagulation profile if necessary

• Full blood count1.Major surgery.2.Chronic bleeding.3.History of anaemia.4.Renal disease.

Clotting screen

1 Clinical evidence of liver disease including a history of hepatitis.

2 Bleeding disorder.

3 Anticoagulants.

Biochemistry

• All patients should have a dipstick urinalysis to measure glucose, bilirubin, protein and ketones.

• In patients aged under 60 years, this is sufficient

• Serum sodium and potassium• hyperkalaemia can predispose to cardiac

arrest, particularly if suxamethonium is given • hypokalaemia can lead to cardiac arrhythmias.

• Urea and electrolytes1. Clinical evidence of renal disease.2. Symptomatic cardiovascular disease.3.Diabetes.4.Drugs-Diuretics, digoxin, steroids

• Liver function tests1.Clinical evidence of liver disease.2.Chronic liver disease, including a history of

hepatitis.

Preoperative Chest X Ray

• to confirm or establish a diagnosis and• evaluate the extent of pathology• to establish a baseline for comparison with

postoperative films

1. Cardiorespiratory disease.2. Possible pulmonary malignancy (primary or secondary).3. Severe trauma.4. Immigrants from countries with endemic TB.

ECG

• Abnormalities are relatively common, between 47% and 52% and correlate with increasing age, male gender and physical status score (ASA).

• According to Gold et al. of the patients with abnormal preoperative ECGs, only 1.6% experienced a perioperative adverse cardiovascular event

• In only half of these was the preoperative ECG helpful.

1. Patients older than 60 years undergoing major surgery.

2. Symptoms and signs of cardiovascular disease, including ischaemic heart disease or hypertension.

3. Symptomatic respiratory disease.

Airway Assessment

• Difficult tracheal intubation accounts for 17% of the respiratory related injuries and results in significant morbidity and mortality.

• Up to 28% of all anaesthesia related deaths are secondary to the inability to mask ventilate or intubate

Difficult Airway

• Where there is a problem in establishing or maintaining gas exchange via a mask, an artificial airway or both

• Anaesthetic factors which could predispose to a difficult airway are:-

• oedema, burns, bleeding• tracheal/oesophageal stenosis• compression or perforation, pneumothorax • aspiration of gastric contents.

• A global assessment should include the following:

1.Patency of nares : look for masses inside nasal cavity (e.g. polyps) deviated nasal septum, etc.

2.Mouth opening of at least 2 large finger breadths between upper and lower incisors in adults is desirable.

• Teeth : Prominent upper incisors, or canines with or without overbite, can impose a limitation on alignment of oral or pharyngeal axes during laryngoscopy

• especially in association with a large base of tongue, they can compound the difficulty during the direct laryngoscopy or bag-mask ventilation.

• An edentulous state, on the other hand, can render axis alignment

• hypopharyngeal obstruction by the tongue can occur.

3. Palate : A high arched palate or a long, narrow mouth may present difficulty.

4. Assess patient’s ability to protrude the lower jaw beyond the upper incisors (Prognathism).

5. Temporo-mandibular joint movement : It can be restricted ankylosis/fibrosis, tumors, etc.

6. Measurement of submental space (hyomental/ thyromental length should ideally be > 6 cm).

7. Presence of hoarse voice/stridor or previous tracheostomy may suggest stenosis.

8. Any systemic or congenital disease requiring special attention during airway management (e.g. respiratory failure, significant coronary artery disease, acromegaly, etc.).

Hyomental Distance – 3 finger breadths

Thyrohyoid distance – 2 finger breadths

Six standards in the evaluation of airway

• Temporomandibular mobility – One finger• Inspection of mouth, oropharynx – Mallampati

classification – Two fingers• Measurement of mento-hyoid distance (4 cm) in adult

- three fingers.• Measurement of distance from chin to thyroid notch –

(5 to 6 cm) – Four fingers• Ability to flex head towards chest, extend head at

atlanto-occipital junction and rotate head, turn right and left (five movements).

• Symmetry of nose and patency of nasal passage.

Mallampatti Classification

• correlates tongue size to pharyngeal size.• Class I : Visualization of the soft palate, fauces;

uvula, anterior and the posterior pillars.• Class II : Visualization of the soft palate, fauces

and uvula.• Class III : Visualization of soft palate and base of

uvula.• Class IV: Only hard palate is visible. Soft palate is

not visible at all.

LEMON airway assessment• The score with a maximum of 10 points is calculated by

assigning 1 point for each of the following LEMON criteria:

• L = Look externally (facial trauma, large incisors, beard or moustache, large tongue)

• E = Evaluate the 3-3-2 rule (incisor distance-3 finger breadths, hyoid-mental distance-3 finger breadths, thyroid-to-mouth distance-2 finger breadths)

• M = Mallampati (Mallampati score > 3).• O = Obstruction (presence of any condition like

epiglottitis, peritonsillar abscess, trauma).• N = Neck mobility (limited neck mobility)

Direct Laryngoscopy

• Grade I – Visualization of entire laryngeal aperture.

• Grade II – Visualization of only posterior• commissure of laryngeal aperture.• Grade III – Visualization of only epiglottis.• Grade IV – Visualization of just the soft palate.• Grade III and IV predict difficult intubation.

Indicators of difficult intubation

• The classic signs altering the operator to difficulty of intubation may be summarised as follows:

• Poor flexion–extension mobility of the head on neck.

• A receding mandible and presence of prominent teeth.

• A reduced atlanto-occipital distance, a reduced space between C1 and the occiput.

• Large tongue size – related more to the ratio of the anterior length of the tongue to the length of the chin or mandible

Preoperative Fasting Guidelines

Preoperative fasting guidelines The volume of liquid ingested is less important than the type of liquid

ingested.

Intake of water up to 2 hrs before induction of anaesthesia.

Other clear fluids *, clear tea and coffee without milk up to 2 hrs before induction of anaesthesia.

Tea and coffee with milk are acceptable up to 6 hrs before induction of anaesthesia.

The volume of administered fluids does not appear to have an impact on patient’s residual gastric volume and gastric pH, when compared to a standard fasting regimen.

Therefore, patients may have unlimited amounts of water and other clear fluid up to two hours before induction of anaesthesia.

* In practice, a clear fluid is one through which newsprint can be read.

The intake of solid foods A minimum pre-op fasting time of 6hrs is

recommended for food (solids and milk). Fried or fatty meal 8hrs is recommended before

induction of anaesthesia.

Chewing gum and sweets Chewing gum should not be permitted on the day of

surgery. Sweets are solid food. A minimum of 6hrs pre-op

fasting time is recommended.

• Higher-risk patients should follow the same pre op fasting regime as healthy adults, unless contraindicated.

• Adults undergoing emergency surgery should be treated as if they have a full stomach.

• If possible, the patient should follow normal fasting guidance to allow gastric emptying.

• *High risk of regurgitation and aspiration; patients include those with obesity, gastro-oesophageal reflux and diabetes.

Ingested Material Minimum Fasting Period

Clear liquids 2hrsBreast Milk 4hrs Infant Formula 6hrsNon-human milk 6hrs Light meal 6hrs