Preoperative assessmentYr 4 Anaesthesia Clerkship

Dr Patricia Chalmers

2010-2011

•Objectives of preoperative assessment•Fasting status•The airway•Volume status•Systemic effects of anaesthetic agents•Allergies and genetic considerations•Risk Stratification•Respiratory and cardiovascular assessment•Patient sketches•Overview of history and examination

Preoperative Assessment

Objectives• To deliver good quality care• To establish doctor-patient rapport• To establish a clinical picture of the patient• To identify risk factors• To draw up a management plan• To optimise any concurrent medical conditions• To minimise the occurrence of critical incidents

in the perioperative period

Clinical Picture

Full medical history and physical examination

Points of specific relevance to anaesthesia:

RISK STRATIFICATION

General health of patient and functional capacity

Surgical procedure

Concurrent medical conditions and medication

History of reactions and allergies to anesthesia THE AIRWAY

Fasting Status Volume Status

FASTING STATUS

FASTING STATUS

6 hrs solids

4hrs liquids

(2hrs clear fluid /water)

The Full StomachMechanisms

• Reflux

• Delayed gastric emptying

• Raised abdominal pressure

• Pharyngeal and laryngeal incompetence

The Full StomachClinical conditions

GORDOpioidsAutonomic neuropathy: diabetesPregnancyIntestinal obstructionTraumaHead InjuryMyopathies/ bulbar palsy

Preoperative measures to reduce risk of aspiration

• Proton pump inhibitors

• H2 blockers

• Metoclopramide

• 0.3M Sodium citrate 30ml

• Nasogastric tube where applicable

(Induction of anaesthesia: RSI)

THE AIRWAY

THE AIRWAY

• Examination Facial swelling• Mouth opening• Dentition• Macroglossia• MALLAMPATI GRADE• Thyromental distance• Neck shape and mobility

Mallampati Grades

Mallampati Grades

Volume Status

VOLUME STATUS

Assess preoperative deficit

a.Clinical picture

b.Formula

Volume Status

TBW 70kg male

55-60% Body weight 45l

Intracellular 30 L

Extracellular 15 L interstitial 12L intravascular 3L

Clinical DehydrationBody wt loss S&S5% thirst, dry mouth

5-10% reduced peripheral perfusion, reduced skin turgor, oliguria, postural hypotension, tachycardia reduced CVP, lassitude,

10-15% inc RR, hypotension, anuria, delirium, coma

>15% Life threatening

Formula

• 4mls/kg/hr for first 10 kg body weight

• 2mls/kg/hr for the next 20kg body wt

• 1ml/g /hr for every other kg body weight

• Adult 2mls/kg/hr

Fluid replacement

• Replace existing deficit: 50% deficit in 1st hr, 25% in 2nd hr, 25% in 3rd hr• Maintain fluid balance 2mls/kg/hr

• Deficit: fasting/ burns/GI losses

• Consider ongoing losses

Effects of anesthetic agents and drugs

• Respiratory depression, impaired lung function →, HYPOXIA

• Depressed myocardial function →HYPOTENSION arrthymias,

• Impaired delivery of O2 to the tissues

Effects of anaesthetic agents on respiratory function

• Depression of RC

• Diminished muscle tone

• Reduced lung compliance(loss of elastic recoil)→ ↓TLC ↓TV ↓FRC and ↑Closing volume

• Atelectasis

• ↑Dead space(respiratory circuit)

Increased work of breathingIncreased ventilation /perfusion mismatch

Effects of anaesthetic agents on cardiovascular functionReduced contractility

Reduced stroke volume

Vasodilatation

Hypotension

Risk of reduced coronary perfusperfusion

Effects of anesthetic agents and drugs (contd)

• Metabolism and elimination of drugs dependent on hepatic and renal function

• Muscle relaxation and paralysis

• Stress Response

• Adverse effect on co-morbidities

Perioperative Clinical Risks

• Respiratory depression

• Cardiac ischaemia

• Arrthymias

• Myocardial infarction

• Stroke

• Renal impairment

Risk Stratification

• ASA grades

• Surgical procedure

• Age

• BMI

• Elective v Emergency

ASA GRADING

1. Healthy Patient

2.Mild systemic disease with no impact on life

3.Systemic disease with limiting factors

4. Systemic disease with a constant threat to life

5. Moribund patient

Grading of General Surgical Procedures

1. Minor eg skin lesion

2. Intermediate eg inguinal hernia arthroscopy

3. Major eg hysterectomy,

4. Major+ eg colonic resection, radical neck dissection,

Preoperative assessment

• Is there any evidence of active disease?

• Are there any clinical risk factors?

• What is the patient’s functional capacity?

• What maintenance medication is the patient on?

• How can we optimise the patient’s clinical condition?

Patient sketch 1

• 53 year old female for ligation of varicose veins• She has a history of asthma and neglects her

medication• o/e anxious • RR 24/min• widespread rhonchi• PEF 65% • Other systems unremarkable

Patient sketch 2

• 64 yr old male with intestinal obstruction for a laparatomy

• History of COPD previous heavy smoker • Gets breathless walking uphill or fast on

level ground • Coughing purulent sputum• FEV1 75%• On combined therapy with beta 2 agonist

and anticholinergic

Preoperative measures to improve lung function

• Stop smoking

• Chest physio

• Bronchodilators

• Antibiotics

• Steroids

Patient sketch 3

• 55yr old female for hysterectomy

• Diabetic on twice daily insulin

• BP 140/90

• What investigations and management

22 kg child for removal of plaster cast

Fasting from midnight In theatre at 10.00amWhat is her fluid deficit?

Patient sketch 4

84 yr old female with a fractured neck of femurTripped in bathroom lives alone and lay there for 20 hours She is thin stature, lives on tea, toast and cakeHistory of CCF On diuretics

? Considerations and management

Patient Sketch 5

Patient Sketch 6

40 yr old male for elective cholecystectomy

Heavy smokerHR 80/min BP 200/115Hb 14.0 gm/dlUrea 8 mmols/lCreatinine 140mmols/l

40 yr old male for cholecystectomyHR 80/min regBP 150/95Hb 12.8 gm/dl Urea 5.8 mmols/lCreatinine 115 µmols/l Na 130mmols/lK 4.5mmols/l

Patient sketch 7

Patient sketch 8

• 44 year old female for mastectomy and reconstruction

• 5 year history of angina, becoming more frequent and increasing in severity over past 6 months

• Both parents died from myocardial infarction• Coronary angiogram 2yrs ago no vessel disease • Ca antagonists,glyceryl trinitrate, isosorbide

dinitrate, verapamil,

Risk Factors Investigations Management

Perioperative Cardiac Risk in relation to noncardiac surgery

• Hi >5%: Vascular Aortic and peripheral vascular surgery

• Intermediate 1-5%: intraperitoneal, intrathoracic, carotid endarterectomy, head and neck , orthopaedic, prostrate,

• Lo risk <1%: endoscopic, superficial, cataract, breast, day stay procedures

ACC/AHA 2007 guidelines

Preoperative measures to improve cardiovascular status

• Continue maintenance meds• Control heart failure• Stabilise arrthymias• Stabilise uncontrolled hypertension• Lo dose short acting beta-blockers for IHD if Hi

or intermediate risk • Statins considered• Prophylactic antibiotics for valvular

disease/prosthesis

Systematic enquiry • RS

• CVS• GIT HH GORD PUD

• Renal system

• Hepatic system• Endocrine diabetes thyroid

• Bone joint and ct disorders RA• Haemotological anaemia coagulopathy DVT

• Neurological and muscular epilepsy

Systematic Enquiry (contd)

• Medications Diuretics, Steroids, Diabetes, Epilepsy, Anticoagulants etc

• Allergies

• Social history Smoking, Alcohol

• Previous Anaesthetic history PONV

• FH genetic disorder SUX apnoea MH

• Fasting status 6hrs (2hrs clear fluids)

Age ASA Surgery Spec cons

FBC Elderly 2-5 2-4 Pallor

hge

U&E’s Elderly 3-5 3-4 Dehydration

G&H/ X-match

3-4 Poly-trauma

ECG M>40,

F>50

CVS 2

RS 3

2

CXR CVS 2

RS 3

Pneumonia

Investigations

INVESTIGATIONS– FBC– U&E’S

Where indicated– Group & Hold/X-match– ECG– CXR– Glucose– Coag screen (spinal, epidural)– BGA– Cardiac ultrasound– RFT’s

Key Points (1)History: Full systemic history

• Medications for maintenance

• Allergies

• Add previous anaesthetic history PONV• FH Sux apnoea, MALIGNANT HYPERTHERMIA

FASTING status

Anaesthetic Risk Stratification

Key Points (2)Examination: Full systemic examination

Add THE AIRWAY

Consider Volume status G&H/X-match

Obtain Consent

Discuss pain management ---reassure

Continue maintenance meds

Draw up Anaesthetic Plan

Bear in mind effects of anaesthesia on patient and effects of co-morbidities on the anaesthetic technique

Recommended Reading

Neville Robinson, George Hall“How to Survive in Anaesthesia”

BMJ Books 2nd Ed 2002