1.
Principles of Preoperative
evaluation
and preparation
Mahmood Hasan Taha
H.D Anesthesia
Head of Anesthesia Dep.
Zakho Emergency H.
April 2018

2.
Reason for evaluation
Anesthesia and surgery are physiologically stressful.
 Invasive interventions may exacerbate or uncover
underlying disease process.
 most feared complications:
difficulty in oxygenation, ventilation,
myocardial infarction , and cerebrovascular accidents.

3.
 Allows the anesthesiologist, surgeon to
stratify and reduce risk for the patient.
 Screen for and manage co-morbid disease.
 Identify need for specialized technique.
 Identify need for advanced post-op care.

4.
Avoid unnecessary delays/cancellations.
Motivate patients to improve pre-op.
outcome.
 Obtain informed consent.

5.
Why is anesthesia risky?
Difficulty in obtaining an airway (adequately
oxygenate and ventilate). Injury during airway
management.
Induction: time of hemodynamic stress;
hypotension, hypertension, arrhythmias,
arrest.
Maintenances: differing degrees of
stimulation, fluid shifts, blood loss.

6.
Emergence: physiologically stressful, secure
airway may be lost, hypothermia.
Anaphylactic reactions to medications.
 positioning.
 Spinal/epidural/regional carries risk ?!!

7.
Evaluation Steps

8.
1. History:
present illness, PMH, PS/AH, Social H.,
drugs., Exercise and METs.
2. Examination:
Airway, CVS, Resp., Musculoskeletal,
Neurological, Peripheral vasculature, BMI.

9.
3. Investigations.
4. Risk of anesthesia and suspected surgery.
5.Marking the site/side of operation.
6.Informed written consent.

10.
The ASA Physical Status Classification
Example
Definition
ASA
Non-smoker
Normal healthy patient
1
Smoker, BMI 30-40,
pregnant, well
controlled HTN/DM
Mild systemic disease (no functional
limitations)
2
Poorly controlled
HTN/ DM
Sever systemic disease (some functional
limitation)
3
Recent MI, CVA,
sever CHF
Sever systemic disease that is a constant threat
to life
4
Ruptured AAA
Moribund patient who is not expected to
survive without the operation
5
Brain dead pat. whose organs are being
removed for donation
6
e.g. ASA 2E
Emergency
E

11.
Airway Examination
 Teeth and bite.
 Mouth opening (inter-incisor distance).
 Mallampati score.
 Thyromental, Hyomental distances.
 Length & thickness of neck.
 Range of motion of head & neck.

12.
Mallampati Classification
(pharyngeal view)

13.
Mallampati Class ?

14.
Mallampati Class ?

15.
Thyromental distance

16.
Clinical Predictors of Increased
Perioperative Cardiovascular Risk
MINOR
 Advanced age.
 Abnormal ECG, Abnormal Rhythm.
 Low functional capacity (e.g. inability to climb
one flight of stairs with a bag of groceries).
 History of stroke.
 Uncontrolled systemic hypertension.

17.
Functional Capacity and Metabolic
Equivalent:
 1 MET: Can you take care of yourself? Eat,
dress, use the toilet? Walk a block or two on
level ground.
 4 METs : Do light work around the house like
dusting or washing the dishes? Climb a flight
of stairs.
 >10 METs : Participate in sports like swimming
, tennis, football , basketball..?

18.
Perioperative cardiac
and long-term risks
are elevated in
patients unable to
obtain 4-MET Demand .

19.
 INTERMEDIATE
 Mild angina pectoris.
 Previous MI (>1month).
 Compensated heart failure.
 Diabetes mellitus (particularly insulin type).
 Renal insufficiency (creatinine >2.0).

20.
MAJOR
 Acute (<7day) or recent MI (<1month) with
evidence of ischemic risk.
 Unstable or severe angina.
 Decompensated heart failure.
 Significant arrhythmias.

21.
 High-grade AV block.
 Symptomatic ventricular arrhythmia.
 SVT uncontrolled rate.
 Severe valvular disease.

22.
Surgery-specific risk
.

23.
Low risk (<1%):
Endoscopic procedures.
Superficial procedures.
Cataract surgery.
Breast surgery.

24.
Intermediate risk (<5%):
 Carotid.
 Head and neck surgery.
 Intraperitoneal and
intrathoracic procedures.
 Orthopedic surgery.
 Prostate surgery.

25.
High risk (>5%):
 Emergent major operations,
particularly in elderly.
 Aortic and other major
vascular surgery.
 Surgical procedures
associated with large
fluid shifts and/or blood loss.

26.
Evaluating Respiratory Disease
Risk Factors for Pulmonary Complications:
 Urea > 40 mg/dL.
 Age > 70.
 COPD.
 Neck, thoracic, upper abdominal, aortic or
neurological surgery.

27.
 Prolonged procedures (> 2 hours).
 Emergency surgery.
 Hypoalbuminaemia (< 30 g/L).
 Exercise tolerance < 1 flight of stairs, <100
yards (<91M).
 BMI > 30.

28.
URTI & anesthesia
 Mild symptoms → can usually proceed.
 Severe symptoms or underlying disease →
postpone.
 Risk of increased bronchial reactivity and LRTI
→ postpone.
 Spinal ?! Epidural ?!

29.
Diabetes Mellitus
 FBS > 126mg/dl, HbA₁c ≥6.5%.
 Should be well controlled prior to elective
surgery. ( 150 – 180mg/dl ?).
 Surgical stress promotes hyperglycemia in the
diabetic patient.
 Perioperative morbidity - end-organ damage.

30.
 ⅓ -½ of patients with type2 DM may unaware
of their condition till time of surgery.
 Preoperative CXR in DM in more likely to
uncover cardiac enlargement , pulmonary
vascular congestion, pleural effusion, although
it is not routinely indicated.

31.
 ECG: Silent ischemia.
 DM with HTN → 50% autonomic neuropathy.
 DM > 10 years → CAD.

32.
Problems of DM with Anesthesia
 Autonomic neuropathy.
 Delayed gastric emptying.
 Renal impairment.
 limited mobility of joints.

33.
Smoking and Anesthesia

34.
 Nicotine half-life: 1-2 hrs.
 Carbon monoxide (CO) half-life: 4hrs.
 Bronchociliary function improves within 2-3days of
cessation.

35.
 Sputum volume decreases to normal levels
within 2 weeks.
 Smoker with irritable air way, wheezy chest ?
Mask A ?, LMA ?, ETT ?
Smoking immediately before surgery…?!!

36.
Hookah
(Water pipe Tobacco Smoking)

37.
 Other names: narghile, arghile, shesha.
 No indication that water pipe tobacco
smoking (WTS) is less risky than cigarette
smoking.
 Word wide icreasing among adolescents and
young adults, (30-40% of high school and
college students).

38.
WTS Vs Cigarette
 Studies shows that measurement of total puff
volume; WTS: 50 -80 L of smoke, in contrast
cigarette smokers inhale about 0.5 – 0.8
L/single cigarette, i.e. the ratio is 60 -160
cigarette.
 1.2 times of nicotine, 8 times of CO, 3 times of
nitric oxides, 4-15 times acrolien, 6-31 times
the formaldehyde, 3- 245 times the polycyclic
aromatic hydrocarbones (PAHs).

39.
 Should be carefully assessed preoperatively
with additional precautions and should be
treated in the same manner as a cigarette
smoker.
 A high carboxyhemoglobin levels (15 – 28%)
suggest that patients require special attention.
NR: non smokers: up to 3%, smokers 2-5%,
heavy smokers 5-10%.

40.
 New generation oximeters are highly
advisable.
 Blood sample on the day of the surgery for
measurement of carboxyhemoglobin... ?

41.
Preoperative Medication Management
 What to stop ?
 What to keep ?
 What to add ?

42.
Hold on day of surgery
 Diuretics: unless thiazide for hypertension
unless severe heart failure.
 Insulin & OHA ?!
 ACEI’s or ARB’s (individual choice).
depends on procedure / risk of hypotension

43.
e.g.
Time
NSAIDs
Stop 48 hours pre-op
Warfarin (bridging to
enoxaparin).
Stop 4 days pre-op
Clopidogrel
Stop 7 days pre-op
Stop 6 weeks prior to surgery.
Oral Contraceptive Pills
Aspirin 75 mg usually continued.

44.
Premedication
 Alleviate anxiety/sedation/amnesia
Reduce risk of reflux.
 Manage pain.
 Control perioperative risk.
Dry secretions.

45.
Preoperative Fasting
Guidelines

46.
Minimum Fasting
period
Ingested Material
2 hours
Clear liquids: water, fruit juices without pulp,
carbonated beverages, tea and black coffee
(clear liquids should not include alcohol)
4 hours
Breast Milk
6 hours
Infant formula
6 hours
Non-human milk
6 hours
Light meal (typically consists of toast and clear
liquids)
8 hours
Full, heavy, fatty meal

47.
Preoperative laboratory tests
 No evidence supports the routine use of
laboratory tests.
 Selected tests should based on patient's
preoperative history, physical examination and
proposed surgical procedures.

48.
Unless there has been intervening
changes in patient's status:
•
within 6 months of the
procedure
ECG & Chest X-
Ray
within one month are accepted
in the stable
conditions
Chemistries and hemoglobin/
HTC
not more than 1 week
Coagulation
studies
4 month
intervals
Virology screen

49.
Anticoagulant and antiplatelet
(ASRA recommendations)

50.
Antiplatelet
Aspirin and NSAID
Either medication alone does not
increase risk.
 Normal bleeding time does not indicate normal
homeostasis and vise versa.
 Check for history of bruising, excessive bleeding,
female, old age.

51.
Anticoagulant
Oral anticoagulant: Warfarin
Monitoring: PT and INR.
Must be stopped ideally 4-5 days (normal PT &INR),
this should be discussed with the physician.

52.
Parenteral anticoagulant
Heparin:
 Monitoring: aPTT.
 To be stopped 4-6 hr.
LMW Heparin:
 Half-life: 3-4 times more than Heparin.
 prophylactic dose: wait 10 - 12 hr.
 Therapeutic dose: delay 24 hr.

53.
Anesthesia and Herbal Therapy
Garlic
 Reduces blood pressure
, thrombus formation, and
serum lipid and cholesterol
levels.
 Inhibits in vivo platelet aggregation is dose-
dependent.
 Time to normal hemostasis after
discontinuation : 7 days.

54.
Ginkgo
 Cognitive disorders, peripheral
vascular disease, vertigo, tinnitus,
and altitude sickness.
 Inhibits platelet activating factor.
 Time to normal hemostasis after
discontinuation :36 hrs.

55.
Ginseng
 Protects against effects of stress.
 May inhibit the coagulation cascade.
 Time to normal hemostasis after
discontinuation – 24 hrs.
These represent no added risk for
spinal hematoma

56.
Summery
 Preoperative evaluation is mandatory.
 The anesthetist is uniquely qualified to
evaluate the risk and he is responsible for
deciding fitness for anesthesia.
 The risk is cumulative of: medical + surgical.

57.
 Preoperative investigation should be
requested according to its indications, routine
(blanket )preoperative investigations waste
resources & time.
 Mendelson’s syndrome may be fatal, there for
fasting time should be taken seriously.