Pre Anesthetic Evaluation

Pre-operative Assessment

Dr.Vithal DhulkhedProfessor and Head ,Dept of Anesthesiology

Krishna Institute of Medical Sciences (Deemed University)Karad, Maharashtra

PURPOSE OF THE PREOPERATIVE EVALUATION BY CONSULTING PHYSICIAN

The purpose is not to give medical clearance but rather informed clinical judgment to the anesthesiologist and the surgical team

The patient’s current medical statusRecommendations regarding the

management and risk of cardiac(other) problems during the periop Period

The patient’s clinical risk profile, to assist with treatment decisions that may affect short- or longterm cardiac (other)outcomes.LEE A. FLEISHER, MD Robert D. Dripps Professor and Chair, Department of Anesthesiology and Critical Care,and Professor of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA

THE OBJECTIVES OF PRE-OPERATIVEASSESSMENT

The aim in assessing patients before anaesthesia and surgery is to improve outcome.

This is achieved by:Identifying existing medical conditionsIdentifying potential anaesthetic difficultiesImproving safety by assessing and quantifying riskAllowing planning of peri-operative careProviding the opportunity for explanation and

discussionAllaying fear and anxiety for the patient and

relatives

This will only be achieved when all health professionals work as a team [2].

THE OBJECTIVES OF PRE-OPERATIVEASSESSMENT

Good pre-operative assessment will help to:Reduce costsIncrease efficiency of operating theatre time

Such action should:Reduce the number of patients who fail to attend

on the day of surgeryReduce cancellation of surgery for clinical reasonsProvide an opportunity to discuss with patients any

self- help matters to improve outcome (e.g. stopping smoking or losing weight).

Patients should have access to easily understood information.

Preoperative Assessment

ObjectivesTo deliver good quality careTo establish doctor-patient rapportTo establish a clinical picture of the patientTo identify risk factorsTo draw up a management planTo optimise any concurrent medical conditionsTo minimise the occurrence of critical incidents

in the perioperative period, drug interactions

Co-existing Medical Problems and Perioperative Death (NCEPOD 2002)

% of pts

• Approx75% who suffer periop death have CVS disease

Perioperative Stress With increasing surgical risk there is need to increase

VO2 for several days post op

Postop mortality - function of preop cardiopulm failure, not Misch

Surgical risk for cardiac events are related to the urgency, magnitude, type, and duration of the procedure, as well as the change in body core temperature, blood loss, and fluid shifts

OER- Oxygen Extraction Ratio

.

Perioperative Stress…………….

Inability to increase CO is periop cardiac failure (PCF); focus on detection of forward CF.

It, is frequently occult in elderly;manifests as reduced exercise tolerance;

Normally elderly patients adjust their level of activity when O2 demand>supply. The postop patient does not have this option

Surgery Related Risk*High Risk (Risk >

5%):Emergent major

operationsAortic and other

major vascularPeripheral vascularAnticipated prolonged

or associated with large fluid shifts and/or blood loss

Intermediate Risk (Risk < 5%):

Carotid endarterectomy

Endovascular AAA repair

Head and neck

Intraperitoneal and intrathoracic

Ortho,uro,neuro major

Low Risk Surgery (Risk < 1%): Endoscopic

procedures Superficial

procedure Cataract

surgery Breast

surgery Gynaecolo

gy Reconstru

ctive Minor

ortho,uro

*Risk of MI and cardiac death within 30 ddays of surgery

10

Perioperative Stresslow risk surgery -postopVO2 need <120 ml/min/m2

intermediate risk -VO2 120-150.

high risk surgery >150 ml/M2. 40% over basalNeed to increase VO2 by 50%. for several days

Post op In normal exercise OER can increase to 75%, but

after an operation OER is only 30%. Requiring 2.5-fold increase in postop CO

Post op mortality is a function of preop cardiopulm failure and not MIsch

OER- Oxygen Extraction Ratio

Patient Factors

Age

Existing Co-

morbidity

Exercise Tolerance

Medication

Patient Factors……….The low risk group < 60 yrs with no history

of cardiopulmonary disease or non-specific ECG changes, may proceed to surgery with little evaluation.

The high-risk group includes acute coronary

syndromes, decompensated cardiac failure, recent MI and supraventricular arrhythmias. -need further assessment and management.

Patient Factors……….Intermediate group >60 yrs ;stable angina,

previous MI, compensated or prior CCF and DM, determine functional capacity

The ideal screening test should provide an accurate assessment of myocardial function, detect M ischaemia, and be non-invasive,easily performed in elderly patients, reproducible and cost effective

What is important in screening?“History-taking and the physical examination are

still the best means of preop screening, and

Lab tests other than those indicated by history and physical examination are not cost effective, do not provide medicolegal protection, and in fact may harm the patient" (Roizen, 1987 ).

History Taking

Chart reviewPresent illnessFamily History: porphyria, malignant

hyperpyraxia, haemophilia, cholinesterase abnormalities and dystrophy myotonica .

Disease of CVS & RS, exertional dyspnoea, paroxysmal nocturnal dyspnoea, orthopnoea, angina of effort, MI and COPD.

History Taking ........Hematological Disease : Anemia , Clotting

abnormalities , Thromboprophylaxis .Musculoskeletal Disease : Rheumatoid Arthritis .Renal Disease : Renal Failure , Patients on

Dialysis . CNS Disease: Seizures , TIA , Stroke, Raise ICP.GI: Liver Disease , GERD , vomiting , diarrheaEndocrine Disease: Diabetes Mellitus

GERD-Gastroesophageal reflux dis

History Taking ...........

Allergy to drugs, food, antibiotics, anesthetic agent, latex allergy and atopic patient

HBV,HCV,HIV carriers have additional risk on staff.

Special Precaution in infected patient:

A history of previous anaesthesia .

Sore throat and headache Post-operative nausea or vomiting.Expose to Halothane within 3 mths priorDVT problem.Difficulties with tracheal intubation.

PregnancyIf it’s elective surgery then postpone it till

delivery.

Many anaesthetic are teratogenic especially in early stage.

They may induct spontaneous abortion.

Smoking; Alcohol Smoking indicate: CVS problems , chronic

bronchitis or Lung CA. Causes tachycardia, increase peripheral

resistance, decrease the availability of O2 by 25%, and increase RS complications by 6 folds.

Stop 1 month prior ; or at least 6 hours before.

Alcohol causes induction of liver enzyme, hepatic & cardiac damage, post-op delirium tremors due to withdrawal

Drug HistoryCVS medication: ACE Inhibitors, Diuretics,

B-Blockers, Calcium channel blockers Antibiotics: Aminoglycosides,Sulphonamides.Anticoagulant: Warfarin, Aspirin, oral

contraceptive, hormone replacement therapyLithium and Insulin . Some drugs must be stopped before

(contraceptive tablets .warfarin and MAOI )

Physical ExaminationFull examination must be done even if it’s a

minor surgery.General: color, activity, weight, dehydrated,

& type of breathing.CVS: pulse volume, rate, and pressure, heart

sounds, & BP.RS: Breathing sound, chest expansion,

airway and trachea.Assessment of the ease of tracheal

intubation.

Physical ExaminationTeeth should be inspected for caries, caps

and loose teeth.Mouth opening – Flexion of cervical spine &

extension of Atlanto-occipital joint.CNS : cranial nerve examination , Eye

Examination , Peripheral sensory & Motor Dysfunction

Anaesthetic history/assessmentFamily historyPrevious anaesthetics

PONVallergymalignant hyperpyrexiadifficult airwaydifficult IV access

Airway assessmentBest done by an anaesthetistCertain features of concern

small mouthpoor dentitionlimited neck mobilityscars/surgery/anatomical abnormalitiesobesity

Mallampati scoring system

Preoperative investigationThe request for pre-operative investigations

should be based on: Factors apparent from the clinical assessment The likelihood of asymptomatic abnormalities The severity of the surgery contemplated Unnecessary lab testing is still common. A

substantial excess cost is incurred due to this

Barnard N A, Williams R W, Spencer E M.  Preoperative patient assessment: a review of the literature and recommendations. Ann R Coll Surg Eng 1994; 76: 293-297

Chest X-ray Age >60 Significant RS disease CVS disease , If not done on last year, Rheu arthritis, thyroid goitre, diphtheria, malignancy

Electrocardiogram Age >50 CVS disease DMRenal disease

Full Blood Count Age >60 ,Clinical anaemia (?include for Hb age.<6mths,>40y or female:If Hb not obtained in 2mths,smoking >40 PY ) Haematological disease Renal disease ,Chemotherapy Procedures with bl loss > 15% Random Blood Sugar

Age > 60 Symptoms of DM, DM, Liver dysfn, CNS dis, surgery involving interruption of bl supply to brain, Steroids, BMI>33 and no test in 2 mths

29

(These tests are recommended for administration of anaesthesia and are not intended to limit those required for issues specific to their surgical management)Note: For healthy patients undergoing short, minimally invasive procedures, investigations may not be necessary.

PFT COPD,Dyspnoea, OrthpnoeaTo test reversibility of bronchospasm, anticipated postop intubation, lung rsection

Coagulation Profile Haematological disease Liver disease ,SLE, MalnutritionAnticoagulation Intra-thoracic/Intra-cranial procedures Acute major traumaPreeclampsia, Vascular dis Renal disease

Renal Profile Age >60 , Morbid obesityRenal disease ,Liver disease DM, CVS, renal disease Procedures with bl loss > 15% Stable and unstable symptom swith no test for 2 mthsSteroids, diuretics, drugs excreted by kidney

Liver Function Tests Hepatobiliary disease Alcohol abuse

Pregnancy Test Patient is of child-bearing age and is sexually active and history suggests possible pregnancy, e.g., delayed menstruation, or patient is concerned about possible pregnancy or if possibility of pregnancy is uncertain

Common causes for postponing surgeryAcute upper respiratory tract infection.Untreated medical diseases.Inadequate resuscitation in emergency( 1/3

of fluid lost ) in dehydrated pt & low BP in shock pt.

Recent ingestion of food.Failure to obtain informed consent.MI : wait 6 months

Dripps/ASA ClassificationClass Systemic Disturbance Mortality*1 Healthy patient with no disease outside of the surgical

process<0.03%

2 Mild-to-moderate systemic disease caused by the surgical condition or by other pathologic processes

0.2%

3 Severe disease process which limits activity but is not incapacitating

1.2%

4 Severe incapacitating disease process that is a constant threat to life

8%

5 Moribund patient not expected to survive 24 hours with or without an operation

34%

E Suffix to indicate an emergency surgery for any class Increased

32

The Assessment of Dyspnea

Grade 0 No dyspnea while walking at a normal paceGrade I “I am able to walk as far as I like provided I

take my time.”Grade II Specific street block limitations – “I have to stop for a while after one or two blocks.”Grade III Dyspnea on mild exertion –“I have to stop and rest while going from kitchen to bathroom.”Grade IV Dyspnea at rest,

Risk assessment of cardiovascular diseases

Cardiovascular Risk Assessment • Static Testing

o Electrocardiographyo Transthoracic Echocardiographyo Transoesophageal Echocardiographyo Cardiac catheterisation

• Dynamic Testing o Exercise ECG testingo Dobutamine stress echoo Dipyridimole stress echoo Dipyridimole thallium scintigraphyoCardiopulmonary exercise testing

Useful adjunct in evaluating CAD, not recommended for PAE functional assessment

Stepwise Approach to Preoperative Cardiac Assessment

Need for emergencynoncardiac

surgeryOperating room

Evaluate and treatper ACC/AHA

Guidelines

Vigilant perioperative and postoperative

management

Consider Operating Room

Low RiskSurgery

*Active cardiac

conditions

No

Yes

YesNo

Proceed withplanned surgery

Asymptomatic andgood functionalcapacity >4MET

Yes

Proceed withplanned surgery*

NoYes

Manage based onclinical risk factors

No or unknown

•Acute or recent MI (7-30 d) Unstable coronary syndrome•Decompensated CHF Significant Arrhythmias Severe Valvular Disease

*Noninvasive testing may be considered before surgery in specifi c

patients with risk factors if it will change management.

Manage based onclinical risk factors

3 or more clinical

risk factors*

1 or 2 clinical

risk factors*

No clinical risk factors*

Vascular Surgery

Intermediate risk surgery

Vascular Surgery

Intermediate risk surgery

Proceed withplanned surgery

Proceed with planned surgery with HR controlor consider non-invasive testingConsider Testing

*Clinical risk factors = known ischemic heart disease, compensated or prior HF, diabetes, renal insufficiency, cerebrovascular disease

Cardiopulmonary Exercise Testing

• Examines the ability of the CVS to deliver oxygen to tissues under stress

• Exercise at known work rate on ergometer while a number of variables are measured: o (1)  ECG o (2)  Blood pressure; o (3)  Expired air flow; o (4)  O2 uptake from the air; o (5)  CO2 output from the body; o (6)  Arterial blood gases.

• VO2 - volume of oxygen consumed ml/min (absolute) ml/kg/min (relative)• METS - metabolic equivalents 1 MET = 3.5 ml/kg/min• VCO2 - volume of carbon dioxide produced ml/min

Parameters Measured

• During exercise, when rise in VCO2 becomes disproportionate to rise in VO2

• Indicates the level of exercise where body has reached maximal aerobic capacity

• Termed the Anaerobic Threshold

Classification of Cardiac Failure(CF) by Exercise Testing

Functional Class

Definition VO2 max (ml/min/kg)

AT (ml/min/kg)

A No CF >20 >14

B Mild CF 16-19.9 11-13.9

C Moderate CF 10-15.9 8-10.9

D Severe CF <10 <8

Parameters Measured

Preoperative cardiopulmonary exercise testingDifferentiates cause of dyspnoea due to

CAD,HF restrictive and obstructive lung disease. Evaluates functional status before major surgery.

AT >11 ml/ kg/min -no CV mortality,less hospital stay

<11 ml/ kg/min postop CCULow AT and peak VO2 --with poor outcomeMajor abdominal or thoracic surgery with

significant ischaemia or pulm dysfunction are admitted to HDU postop for ECG and RS monitoring, even if mild CF

Perioperative ManagementRevascularizationBeta blockersStatinsAlpha-2 agonistsCalcium channel blockers Aggressive pain control Avoidance of severe anemia Normothermia Vigilant monitoring

Acute MIHigh Risk ACS

High risk anatomy

Class I recommendations for revascularization - 2004 ACC/AHA guidelines:

1 = stable angina and significant left main disease;

2 =stable angina and 3 vessel disease, especially when LV EF <50%;

3 = stable angina and 2-vessel disease with significant proximal LAD stenosis and either LV EF<50% or demonstrable ischaemia on non-invasive testing;

4 =high-risk unstable angina or non-STEMI;5 =acute STEMI

Perioperative Beta BlockersAHA/ACC Recommendations: 2006

Update•Beta blockers required in recent past to control symptoms of angina or patients with symptomatic arrhythmias or hypertension•Patients at high cardiac risk owing to the finding of ischemia on preoperative testing who are undergoing vascular surgery•Patients undergoing vascular surgery and with identified CAD•Vascular surgery and multiple cardiac risk factors•Moderate or high risk surgery and multiple cardiac risk factors

Key Point: if known or suspected CAD and undergoing moderate or high risk surgery, use a beta blocker!

Perioperative Statins

Hindler, et al. Anesthesiology 2006;105:1260-72

ACC/AHA 2007 Recommendations: Statins

Class I: Patients currently taking statinsClass IIa: Patients undergoing vascular surgeryClass IIb: Patients with at least 1 clinical risk factor undergoing intermediate risk surgery

Low risk patients (bileaflet Aortic valve, no risk factors*)Stop warfarin 48-72 pre-opResume 24 hrs post-op

High risk patients (mitral valve, aortic valve + any risk factor*)Bridge with UFH, starting when INR < 2

Can anticoagulation be stopped in the patient with a mechanical heart valve?

*Risk factors: AF, previous thromboembolism, LV dysfunction, hypercoagulable state, older generation valve, mechanical tricuspid valve, more than one mechanical valve

Risk assessment of pulmonary diseases

Pulmonary issuesPPC play important role in risk for patientsContribute similar to cardiac complications in

morbidity mortality and length of stay

AtelectasisInfectionBronchitisPneumoniaBronchospasmPulmonary embolism

Exacerbation of underlying chronic lung diseaseRespiratory failure and prolonged invasive or noninvasive ventilationARDS

PPC- Postoperative pulmonary complications

PPC

Preoperative risk factors for PPCs

Age, BMIDyspnea, COPD, OSAInhaled tobacco useNYHA class >II, IHD, arrhythmia, pulmonary

hypertensionNutrition status, lower serum albumin

concentrations, DM, alk PO4 level of 125 U/L, increased complexity scores, and decreased functional status.

Factor or Intervention Incidence PPC

%OR

Age 60-69;70-79 vs <60yrs 2.09;3.04

Smoking 1.26Preoperative chest roentgenograms 12.8% vs

16%),Serum Albumin 3.5 g/dL 22 to 44%COPD;CCF 1.79 ;2.

93Functional dependence,total; partial 2.51;1.6

5In ILD Composite physiologic index (CPI) of > 40

50%

GA; Emergency surgery 1.83;2.21

Noncardiothoracic surgery: duration of surgery

from 2 to 19 ; 2.14

cardiothoracic surgery 8 to 39Esophagectomytranshiatal approach VS transthoracic

(27% vs 57%, respectively;

Ann Intern Med 2006:144:574-580 CPI = 91.0 - (0.65 * % predicted DLCO) - (0.53* % predicted FVC) - (0.34 * % predicted FEV1).

ILD-Intersitial Lung disease

Preoperative pulmonary assessment

Spirometry ,forced-vital capacity (FVC), maximal inspiratory and expiratory (MEP) pressures, and peak cough flow (PCF).

For patients with FVC < 30%, preop use of noninvasive IPPV to be considered.

Ineffective cough, defined as PCF < 270 L/min or MEP < 60 cm H2O, preop manual- and mechanically assisted cough considered.

Pulmonary function tests: IndicationsLung resection -should have (PFT). CABG , upper abdominal surgery with H/O

smoking or dyspnea. Head and neck, orthopedic, or lower abdominal

surgery with unexplained dyspnea or pulmonary symptoms.

Preop PFT need not lead to cancellation. Even severe COPD, can undergo surgery with an acceptable risk of pulm complications.

Results should be interpreted in context of clinical situation

The Snider Match TestA patient who can extinguish at 15

cm with his mouth wide open has a FEV 0.75 sec of at least 1,000 cc and a PFR of at least 130 liters per min.

Rest five minutes. Take a full breath. Hold it with mouth and nostrils closed. Note time in seconds.

Breath-holding test of 10 to 15 seconds would indicate a vital capacity of 1500 cc. or less

Breath-holding test:

6 minute walk test Inexpensive, easy. How far can walk along a flat corridor,

turning around at each end, at normal pace, in 6 min. Median normal - 500–600 m. Other measurements include

SpO2 , HR ,dyspnoea scale and leg fatigue.>563 m - not routinely CPET; <427 m -further evaluation.

‘uncertainty’ (≥427 but ≤563 m), Consider clinical risk factors and magnitude of surgery in the decision*

less than 300 m -poor prognosis following aortic valve replacement

>350 m for lung volume reduction surgery for management of significant COPD

<200 m predict high 6-month mortality

*Br. J. Anaesth., January 1, 2012; 108(1): 30 - 35.

Stepwise approach to preoperative pulmonary assessment

Age, BMI Dyspnea, COPD, OSA Inhaled tobacco use IHD, arrhythmia, NYHA class II pul hypertension, Nutrition status, lower albumin, DM, alk PO4 level of 125 U/L, high complexity scores, and decreased functional status, pancuronium,surg site duration,GA

Stepwise approach to preoperative pulmonary assessment

Risk assessment of liver diseases

Criterion 1 point each 2 points each

3 points each

Ascites None Controlled with diuretics

Poorly controlled

Encephalopathy

None Grade I-II Grade III-IV

Total bilirubin,

µmol/L (N= 17.1)

mg/dL (N= 1.0)

<

34

(0-2)

34 – 50

(2-3)

> 50

(> 3)Albumin, g/L >35 (>3.5 g/dL) 25-35 (2.5-3.5

g/dL)< 25 (< 2.5

g/dL)INR < 1.7 1.7–2.2 >2.2

Child-Turcotte-Pugh Classification of liver disease

CTP A points = 5-6 , B = 7-9 , C = 10-15 Mortality rate(abdominal surgery.) : class A 10% class B : 30-31% class C- 76-82%

More recently, "integrated MELD" score (iMELD):

iMELD = MELD(3.8 × ln bilirubin value) + (11.2 X ln INR) + (9.6

ln creatinine value), + (0.3 X age) - (0.7 X serum sodium

[mEq/L]) + 100. ),

bilirubin and creatinine values in (mg/dL) ;ln- natural ogarithm

Scores

of < 35, 35-45, and >45 associated with periop mortality rates

of 4%, 16%, and 50%, respectively.

Integrated MELD Score

To summarisePreoperative evaluation should be a team approachHistory and physical examination History-taking and the physical examination are

still the best means of preop screening, and Avoid unindicated lab testsWeigh the risk benefit ratio of surgeryProvide optimal perioperative care by triage

according to risk stratification Patients should have access to easily

understood information

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