Risk Assessment

Risk Assessment

"Perhaps
The most insidious hazard of anaesthesia
is
its relative safety."
It’s not absent
But
unfortunately
anaesthesia-related morbidity and mortality
is rare
Fortunately

There are three components that must be considered when evaluating perioperative risk:

• the patient's medical condition preoperatively.
• the extent of the surgical procedure
• the risk from the anaesthetic.
In general, the major contribution to increased risk is that of the patient's health prior to the procedure and the magnitude of the surgery.
patients often have more fear about their anaesthetic than the surgery itself.
Risk Assessment


• assess the potential risk in performing the desired procedure on a specific patient. accurate risk assessment is meaningful because it leads to a decision to proceed, postpone, or cancel surgery.
• assess the potential risk in performing the desired procedure on a specific patient.

Goals of Risk Assessment

Anaesthetic Mortality
Incidence of Primary
Anaesthetic Mortality
No. in
study
Year
Country
Author
• 1:5,138
• 195,232
1980
• Canada
• Turnbul
• 1:5,059

• 338,934

• 1980

• Finland

• Hovi-Vivander7

1:10,000

108,000
1982
• United Kingdom

• Lunn & Mushin

1:10,000
163,240
1985
• United States
Keenan & Boyen
1:13,207
198,103
1986
France
• Tiret
1:26,000
550,000
1987
Australia
Holland1
• 1:185,000


500,000
1987
• United Kingdom

Buck1

Society of Anesthesiology (ASA) physical status
The ASA physical status classification system was originally proposed in 1941, and revised by Dripps in 1961 to provide a uniform assessment of a patient's preoperative physical condition.
As this system is simple, easy to use, and requires no laboratory investigations, it has now been widely accepted as the standard means of preoperative patient classification.
Risk Assessment

American Society of Anesthesiologists (ASA) physical status classification

• 0.1
• Healthy patient without organic, biochemical, or psychiatric disease
ASA 1
• 0.2
• A patient with mild systemic disease (e.g., mild asthma or well-controlled hypertension). No significant impact on daily activity.
• Unlikely impact on anesthesia and surgery
ASA 2
• 1.8
• Significant or severe systemic disease that limits normal activity (e.g., renal failure on dialysis or class 2 congestive heart failure). Significant impact on daily activity.
• Likely impact on anesthesia and surgery
ASA 3
• 7.8
• Severe disease that is a constant threat to life or requires intensive therapy (e.g., acute myocardial infarction, respiratory failure requiring mechanical ventilation). Serious limitation of daily activity.
• Major impact on anesthesia and surgery
ASA 4
• 9.4
• Moribund patient who is equally likely to die in the next 24 hours with or without surgery
ASA 5
• Brain-dead organ donor
ASA 6


“E” added to the classifications indicates emergency surgery

Risk Assessment

Cardiac Risk
Several perioperative risk studies have attempted to assess which perioperative cardiac risk factors are important.
Ischaemic heart disease has received the most attention because mortality from a perioperative myocardial infarction approaches 50%.
One system is the Goldman Cardiac Risk Index, used in patients with pre-existing cardiac disease undergoing non-cardiac surgery.

Points

History
Age >70 years 5
Myocardial infarction within 6 months 10
Examination
Third heart sound (gallop rhythm), raised JVP 11
Significant aortic stenosis 3
ECG
Rhythm other than sinus, or presence of premature atrial complexes 7
>5 ventricular ectopics per minute 7
General condition
PaO2 <8kPa or PaCO2 >7.5 kPa on air
K+ <3.0 mmol/L; HCO3- <20mmol/L
Urea >8.5 mmol/L; creatinine >200mmol/L
Chronic liver disease
Bed ridden from non-cardiac cause
For each criterion 3
Operation
Intraperitoneal, intrathoracic, aortic 3
Emergency surgery 4
Goldman Cardiac Risk Index


The points total is used to assign the patient to one of four classes; the risks of a perioperative cardiac events are:
• class I (0–5 points) 1%
• class II (6–12 points) 5%
• class III (13–25 points) 16%
• class IV (=26 points) 56%
This has been shown to be a more accurate predictor than the ASA classification.

Risk Assessment

Premedication originally referred to drugs administered to facilitate the induction and maintenance of anaesthesia
Nowadays, premedication refers to the administration of any drugs in the period before induction of anaesthesia.
Premedication

• Patient-related reasons:

1. Sedation
2. Amnesia
3. Analgesia
4. Antisialogogue effect (to dry oral secretions)
5. Medications to decrease gastric acidity and gastric volume.
6. To facilitate induction of anaesthesia.
Indications of premedication


• Procedure-related reasons:
• Antibiotic prophylaxis to prevent infective endocarditis in susceptible patients.
• Gastric prophylaxis (to minimize the risk of gastric aspiration during anaesthesia).
• To avoid undesired reflexes arising during a procedure (e.g., vagal reflex during eye surgery).
• Anticholinergic agents to decrease oral secretions and facilitate a planned awake intubation with a fiberoptic bronchoscope.

Indications of premedication

• Coexisting Diseases:
1. To continue the patient's own medications for coexisting diseases. (e.g., beta blockers, antihypertensive medications, nitrates, antiparkinsonian medications etc.)
2. To optimize the patients status prior to the procedure. (e.g., bronchodilators, nitroglycerine, beta blockers, antibiotics etc.)
Indications of premedication

• Allergy or hypersensitivity to the drug.

• Upper airway compromise, or respiratory failure.
• Hemodynamic instability or shock.
• Decreased level of consciousness or increased intracranial pressure.
• Severe liver, renal, or thyroid disease.
• Obstetrical patients.
• Elderly or debilitated patients.
Contraindications to the premedication


Traditionally, patients were starved of both food and fluids for prolonged periods preoperatively, but it is now increasingly recognized that, apart from certain groups with an increased risk of aspiration, this is not necessary.
Guidelines for preoperative Fasting policy :
• No solid food for 6 h preoperatively.
• No formula milk and non clear fluid for 4 h preoperatively.
• No clear fluids and breast milk for 2h preoperatively.
Chewing gum does not increase gastric volume and is best treated as for clear fluids.
Normal medications can be taken with a sips of water.
There is some factors that delayed gastric emptying.
Preoperative starvation

Questions