Anaesthetic evaluation to predict postop pulmonry complication

1. Ref.: North American Clinics Mar 2016
-Dr. Anuradha T
Jubilee Mission Medical College
Thrissur, India
Preoperative Evaluation
- Estimation of Pulmonary Risk

2.  Postop pulmo compli (PPC) are 2nd MC postop compli, 2-
5.6 %
 Poor outcomes, longer hospital stay, increased mortality
 Clinically significant PPC include... Bronchospasm,
atelectasis, exacerbation of underlying c/c lung
conditions, infection ( bronchitis, pneumonia), prolonged
mechanical ventilation and respiratory failure
 Surgical, anesthetic, pt factors contribute

3.  Aims of preop evaluation :
 Identify risk factors for PPC, change modifiable factors,
discuss risks with patients, optimise health before sx,
plan appropriate periop care
 Overall risk predicted using clinical data
 Do not routinely perform PFT before high risk non
cardiothoracic surgery

4. Pulmo Pathophysiology in Periop
 Mainly restrictive change,measured as reduction in
FRC
 no change in airway resistance.
 Splinting diaphragm- abnormal resp pattern- shallow,
rapid
 Atelectasis in bases,persists >24 hrs in 50% pts
 V/Q mismatch and increased shunt = hypoxia
 Upper abd sx: VC falls by 50%, FRC by 30%
 Lower abd lesser levels

5.  Intracranial, peripheral vascular, ENT 20% fall
 No change with extremity sx
 Decreased resp drive d/t anesthetics, opioids.
Inhibition of cough, impaired mucociliary clearance all
contribute to PPC

6. Preop Risk Assessment
 History & physical examn are most imp
 History must include :
 General health status
 Focused history on pulmonary symptoms- cough,
dyspnoea, exercise tolerance, pre existing lung
diseases

7. Physical Examination
 May help detect unrecognised lung disease
 Look for signs of......
 Asthma
 COPD
 OSA, PAH
 Right heart failure
 Neurological impairment
 Neuromuscular weakness
 Spinal deformity

8. Patient related risk factors for PPC
 General:
 Age,
 General health status, functional status
 Obesity, OSA
 Pulmonary HTN
 Heart failure
 Nutrition
 Neurological impairment

9. Pulmonary Factors :
 Smoking, > 20 pack year. >4 weeks cessation reduces PPC,
longer duration more benefit
 COPD- severe ,high risk for pneumonia, ventiltor dependance
>48 hrs.
 No prohibitive level of PFT below which sx ia absolutely C/I.
Benefit Vs Risk and proceed if indication is compelling.
 Exacerbations of c/c ds or a/c issues eg. Pneumonia- PPC. Are
adequate reason to postpone elective sx

10.  Asthma-
 unclear if h/o asthma carries more risk.
 Poorly controlled asthma – prone for hypoxi,
hypercapnea, bronchospasm, inadequate cough,
atelectasis, pulmo infection after sx.

 ACP 2006 suggest asthma is not a risk factor for PPC

11.  ILD :
 PPC after all types of sx in ILD is higher than general
population. But complications in other sx types are
not as high as after lung sx
 Upper respiratory infection :
 few data. Evidence is weak to recommend
postponement of elctive sx during URI. If URI occurs
within 2 weeks preop, adults may hv increased risk for
bronchospasm, laryngospasm and desaturation. But
this does not increase morbidity or long term
sequelae.

12. Procedure related Risk Factors
 Surgical site- more for upper abd sx. Highest for
esophagectomy
 Duration of surgery & complexity : >3-4 hrs had 40 % PPC. <
2 hours 8%

 Type of anesthesia and analgesia: GA alone more risk.
Consider spinal/epidural + light GA/ nerve blocks in high
risk

13.  Neuromuscular blockade: use intermediate acting
Atrac/Vec + monitoring to avoid any residual NMB
 Open Vs Lap sx : Unclear if PPC are reduced with lap.
Lap shorter stay, less pain, better spirometric values
 Emergency surgery : significant predictor of PPC

14. Preop Pulmonary tests
 PFT :
 Includes spirometry, flow volume loops,DLCO, V/Q scan,
CPET.
 Spirometry is MC. Do not predict PPC.
 2006 ACP guidelines do not reccomend routine preop
use before high risk sx. Should not be used as primary
factor to deny sx
 ABG : PaCO2 > 45mmnhigh risk for PPC. Not an absolute
C/I for major noncardiac sx.
 CXR: routine preop CXR hardly give additional info. ACP
recommends CXR in those with known cardiopulmonary
ds, > 50 yrs for high risk sx

15.  Exercise testing:
 VO2 max and anaerobic threshold are valid predictors of
periop morbidity and mortality.
 Simple ones like stair case climbing capacity and 6-min
walk test are accurate and show concordance with VO2
max
 ECHO : No evidence for routine preop use even in
advanced lung diseases.
 Advised for pts with severe lung disase having features of
right heart failure.
 Also in reduced exercise tolerance to r/o cardiac illness

16. Risk Scores for periop complications
 ARISCAT ( Canet) risk index- 2010: for PPC
 Gupta calculator for postop resp failure 2011: failure to
wean within 48 hours
 Gupta calculator for postop pneumonia-2013
 Arozullah respiratory failure index- 2000

17. CANET/ARISCAT risk index : 7 variables

22. Gupta calculator for postop resp failure
2011: failure to wean within 48 hours
 5 item calculator :
 - Type of surgery
 - Emergency surgery
 - Dependant functional status
 - Preoperative sepsis
 - ASA class

23. Periop Strategies to reduce PPC
 Strategies proven to reduce PPC in high risk pt are
 Preop :
 Smoking cessation > 8 weeks optimal
 Optimising airflow limitation in COPD, asthma
 Treat LRTI
 Lung expansion techniques- incentive spirometry and chest
physiotherapy

24.  INTRAOP :
 Consider intraop analgesia with spinal, regional or
epidural technque when indicated
 Avoid use of long acting NMB
 Intraop recruitment manouvers to prevent atelectasis
 Lap Vs open- consider less invasive surgery
 Fluid management- fluid optimisation with GDT

25.  POSTOP :
 Selective NG tube decompression after abdominal
surgery
 Nutritional support
 Lung expansion manouvers
 Epidural analgesia

26. Summary
 PPC account for 25% of deaths in the first postop
week
 Most significant predictors are – ASA class, functional
class, age, site and duration of surgery
 COPD, dyspnoea, smoking are only moderate risk
factors compared with pt related factors and site of sx
 Risk of PPC canbe predicted using scores with readily
available clinical data
 Do not routinely perform PFT before high risk non
cardio thoracic surgery

27. THANK YOU