This slide presentation covers areas about physiology of respiratory system related to surgery and anaesthesia, definition of postoperative pulmonary complications (PPCs), risk of PPCs, screening for PPC risk and specific management for patients with increased risk.
5. Closing Volume
The volume in the lungs at which
its smallest airways collapse
The air remaining in the lung = Residual volume
Beyond equal pressure point (EPP)
intrapulmonary pressure > intraairway pressure
➡
airway collapse
6. Changes of FRC and CC: Conditions
Decreased FRC
Spine position
Obesity
Pregnancy
General anesthesia
Abdominal pain/splinting
Increased CC
Advanced age
Smoking
COPD
Pulmonary edema
Goldman DR, Brown FH, Guarnieri DM (eds) Perioperative Medicine. New York, McGraw-Hill, 1994.
7. Changes in Pulmonary Function with Surgery
Diaphragm
function
Gas exchangeLung volumes
Control of
breathing
Lung defense
mechanisms
Reduction
in lung volumes
Diaphragmatic
dysfunction
Impaired
gas exchange
Respiratory
depression
Impaired
cough reflex and
mucociliary function
11. Control of Breathing
Residual effects of
preanesthetic or
anesthetic agents
Depression of
hypercapnid/hypoxic
ventilatory drive
from narcotics
Decreased tidal volume
Reduced minute ventilation
Increased PaCO2
Decreased frequency of sigh breaths
Precipitation of sleep apnea
12. Lung Defense Mechanisms in Perioperative Period
coughing Mucociliary clearance
Damage of cilia and
mucous gland
by ET tube and/or
inhaled anaesthetics
Decreased
clearance velocity
by ET tube
Suppression
of cough
by opioids
Reduced muscle
strength due to
neuromuscular
blocking agents
InfectionV/Q mismatchingAtelectasis
15. Factors Associated with PPCs
PPCs
Preoperative
Post-
operative
Intra-
operative
Chronic lung disease
(esp. COPD)
Upper respiratory
tract infection
Age
Smoking
General health status
Nutritional status
Heart failure
pulmonary hypertension
Obesity
obstructive sleep apnea
Type of anaesthesia
Duration of anaesthesia
Surgical site
Type of surgical incision
Inadequate
pain control
Immobilization
16. Age
Age
≥80
70-79
60-69
50-59
Odd Ratio of developing pulmonary complications
0 2 4 6 8 10
1.5
2.28
3.9
5.63
Smetana GW, Lawrence VA, Cornell JE, American College of Chest Physicians. Ann Intern Med 2006; 144: 581.
Age >50 years was an important independent factor of risk
Preoperative
Factors
18. American Society of Anesthesiologist:
Physical Status Classification
Preoperative
Factors
Class Description
ASA 1 A normal healthy patient
ASA 2 A patient with mild systemic disease
ASA 3 A patient with severe systemic disease
ASA 4
A patient with severe systemic disease that is a
constant threat to life
ASA 5
A moribund patient who is not expect to survive
without the operation
ASA 6
A declared brain-dead patient whose organs are
being removed for donor purposes
ASA class >2
confers
!
4.87X
increased risk
(95% CI 3.34-7.10)
19. Chronic Obstructive Pulmonary Disease
Preoperative
Factors
Increased
sputum
production
Airway
inflammation
and edema
Loss of
radial traction
& Elastic recoil
Decreased
airway radius
!
Increased
closing volume
6X
more likely to have
major postoperative
pulmonary complications
20. Asthma
Preoperative
Factors Patients with asthma who are
well controlled
and have a peak flow measurement of
>80% predicted
can proceed to surgery with average risk
22. Effects of Obesity on Pulmonary Function
Low lung volume
➡
Decreased FRC
➡
Decreased airway radius
➡
Atelectasis
➡
V/Q mismatching
However,
obesity has NOT consistently been shown to be a risk factor for PPCs
Obesity should NOT affect patient selection for otherwise high-risk procedure
Preoperative
Factors
23. Obstructive Sleep Apnea
Preoperative
Factors
Odd Ratio (OR)
for postoperative respiratory failure
1.95
(95% CI 1.91-1.98)
Higher incidence of:
Unplanned ICU transfers
Longer length of stay
Pneumonia
Respiratory failure
26. Type of Anesthesia
Intraoperative
Factors
General anesthesia leads to a
!
HIGHER RISK
!
of clinically important
pulmonary complications
than does
epidural or spinal anesthesia
Rodgers A, Walker N, Schug S, et al. BMJ 2000; 321: 1493.
29. History & Physical Examination
COPD
!
CAT score/mMRC
History of exacerbation
Decreased laryngeal height
increased AP diameter
Wheezing/rhonchi
Obesity/OSA
!
Body mass index
Mallampati class
Epworth Sleepiness Score
!
Asthma
!
ACT score, Level of control
History of exacerbation
Wheezing/rhonchi
31. Pulmonary Function Tests
Patients with COPD or asthma with
uncertain optimal symptom/disease
control
Patients with unexplained dyspnea or
exercise intolerance
2006 American College of Physicians guideline:
NOT to be used as the primary factor to deny surgery
NOT to be routinely ordered
Qaseem A, Snow V, Fitterman N. et al. Ann Intern Med 2006; 144: 575.
32. Arozullah Respiratory Failure Index
Preoparative predictor Point value
Abdominal aortic aneurysm 27
Thoracic 21
Neurosurgery, upper abdominal, peripheral vascular 14
Neck 11
Emergency surgery 11
Albumin <3.0 g/dL 9
BUN >30 mg/dL 8
Partially or fully dependent functional status 7
History of chronic obstructive pulmonary disease 6
Age >70 years 6
Age 60-69 years 4
Type of surgery
General
health status
Age
33. Performance of the Arozullah Respiratory Failure Index
Class Point total Percent respiratory failure
1 ≤10 0.5
2 11-19 1.8
3 20-27 4.2
4 28-40 10.1
5 >40 26.6
Arozullah AM, Daley J, Handerson WG, Khuri S. Ann Surg 2000; 232: 242.
34. Canet Risk Index
Factor Adjusted odds ratio Risk score
Age ≤50 years 1 0
51-80 1.4 (0.6-3.3) 3
>80 5.1 (1.9-13.3) 16
Preoperative O 1 0
91-95% 2.2 (1.2-4.2) 8
≤90% 10.7 (4.1-28.1 24
Respiratory infection in the last month 5.5 (2.6-11.5) 17
Preoperative anemia (Hb ≤10 g/dL) 3.0 (1.4-6.5) 11
Canet J, Gallart L, Gomar C, et al. Anesthesiology 2010; 113: 1338.
35. Canet Risk Index
Factor Adjusted odds ratio Risk score
Surgical incision in upper abdomen 1 0
>80 5.1 (1.9-13.3) 16
Duration of surgery ≤2 hours 1 0
2-3 hours 2.2 (1.2-4.2) 8
>3 hours 10.7 (4.1-28.1 24
Emergency surgery 5.5 (2.6-11.5) 17
High risk (42.1%)
≥45 points
Moderate risk (13.3)%)
26-44 points
Low risk (1.6%)
<26 points
Pulmonary complication rate:
37. Perioperative Risk Evaluation: Obstructive Sleep Apnea
Factor Points
A. Severity of sleep apnea based on sleep study (or clinical indicator)
None 0
Mild 1
Moderate 2
Severe 3
B. Invasiveness of surgery and anaesthesia
Superficial surgery under local or peripheral nerve block without sedation 0
Superfacial surgery with moderate sedation or general anaesthesia 1
Peripheral surgery with spinal or epidural anaesthesia 1
Peripheral surgery with general anaesthesia 2
Airway surgery with moderate sedation 2
Major surgery, general anaesthesia
!
3
Airway surgery, general anaesthesia 3
38. Perioperative Risk Evaluation: Obstructive Sleep Apnea
Factor Points
C. Requirement for postoperative opioids
None 0
Low dose oral opioids 1
High-dose oral opioids, parenteral or neuraxial opioids 3
Total score (Score in A plus the greater of the score for either B or C)
Gross JB, Bachenberg KL, Benumof JL, et al. Anesthesiology 2006; 104: 1081-93.
Significantly increased risk
5-6 points
Increased risk
4 points
Low risk
<4 points
39. Risk Assessment: Non-resective-lung Surgery
History and physical examination
Seeking known risk factors for pulmonary complications
Low risk:
Proceed to surgery without
further evaluation
Positive Negative
Identify risk(s) presents
in the patient
Chest x-ray*
Pulmonary function test*
Moderate risk:
Perioperative treatment
to reduce risk
Normal
High risk:
Reconsider indication for
surgery
Perioperative treatment
to reduce risk
Consider shorter procedure
Consider epidural/spiral
anesthesia
Abnormal
43. Smoking Cessation
surgery patients and rapid referral to a smoking-
n program could maximize the cessation period be-
gery, resulting in greater reductions in postoperative
ations in the secondary care setting.
14. Theadom A, Cropley M. Effects of preoperative smoking cessation on
the incidence and risk of intraoperative and postoperative complica-
tions in adult smokers: a systematic review. Tob Control. 2006;15:
352-358.
Figure 3 Meta-regression plot, effect of time of cessation on complications.
153al Smoking Cessation Reduces Perioperative Complications
Mills E, Eyawo O, Lockhart I, et al. Am J Med 2011; 124:144.
Relative Risk (RR)
for postoperative complications
!
0.81
(95% CI 0.70-0.93)
in former smokers
!
0.59
(95% CI 0.41-0.85)
in patients who had ≥4 weeks
smoking cessation
Even cessation of smoking for 2 days may have some benefits:
less carboxyhemoglobin, less effects from nicotine,
improved mucociliary clearance
44. Deep Breathing & Incentive Spirometry
Equally effective (deep breathing vs
incentive spirometry)
50% reduction of postoperative
pulmonary complications
Incentive spirometry is recommended
after upper abdominal and thoracic surgery
45. Continuous Positive Airway Pressure
Improved oxygenation
Reduced incidence of
pneumonia, intubation, and
admission to an ICU
However, CPAP may cause
patient discomfort
gastric distension
barotrauma
Zarbock A, Mueller E, Netzer S, et al. Chest 2009; 135: 1252.
commended as a secondary intervention for
refractory atelectasis
➡
46. Specific Management: COPD
Continue current medications (if stable)
Give regular bronchodilator therapy
(Ipratropium/Tiotropium) for 24 hr prior to
surgery until 24 hr postextubation
Give systemic steroid (e.g. dexamethasone 4
mg iv) 1-2 doses 12 hr prior to surgery in
severe symptomatic patient or patient with
frequent exacerbation
Continue systemic steroid for 3-5 days in
severe cases (but no more than 7 days)
47. Specific Management: Asthma
For patient with controlled asthma:
Continue current asthma medications
Apply inhaled rapid-acting beta agonist 2-4 puffs or
nebulizer treatment within 30 minutes of intubation
Give nebulizer treatment in the perioperative period
(~24 h after extubation)
For patient with partly or uncontrolled asthma:
Systemic glucocorticoid (e.g., dexamethasone 4 mg)
1-2 doses in 12 hour prior to surgery may be used
Systemic glucocorticoid may be continued for 3-5 days
in severe cases
48. Specific Management: Morbid Obesity
Administer induction drugs, opioids, and
neuromuscular agents using ideal body
weight (IBW) NOT total body weight
Positioning in“ramped”and“reversed
Trendelenberg”position
Awake intubation in patient when mask
oxygenation is inadequate
Application of 100% oxygen with PEEP 10
cmH2O for 5 minutes before the induction
of anesthesia ± PEEP 10 cmH2O thereafter
50. General Evaluation Steps
1 2 3
4
5
Spirometry DLCO
Predicted
postoperative FEV1
Predicted
postoperative DLCO
Simple
exercise test
Cardiopulmonary
exercise test
FEV1 2 L for
pneumonectomy
FEV1 1.5L
for lobectomy
>80% of Predicted
normal
DLCO
>80% predicted
PPO FEV1
>60% predicted
!
PPO DLCO
>60% predicted
>400 m
shuttle walk test
!
>22 m
stair climbing test
Unexplained
symptoms?
>30%
<30% VO2 max
>20 mL/kg/min
Averaged risk Increased risk High risk