Preoperative pulmoanary evaluation other than lung resection surgeries

1. Pre-operative Pulmonary evaluation
other than lung resection surgeries
DR. PARIKSHIT H. THAKARE
DEPARTMENT OF PULMONARY MEDICINE
TNMC & BYL NAIR HOSPITAL
MUMBAI

2. Why it is necessary??
Postoperative pulmonary complications contribute significantly to overall
perioperative morbidity and mortality rates.
25% of deaths occurring within 6 days of surgery
Frequency rate of these complications varies from 5-70%
It is more important in elective surgeries than emergency.

3. Goals of perioperative pulmonary management:-
1) To identify patients at high risk of significant postoperative pulmonary
complications (PPC)
2) Appropriate interventions to minimize that risk

4. Postoperative pulmonary complication is an abnormality that produces identifiable
disease or dysfunction, is clinically significant, and adversely affects the clinical
course.
Atlectasis
Infection (Eg, Bronchitis, Pneumonia)
Prolonged Mechanical Ventilation
Respiratory Failure
Exacerbation Of An Underlying Chronic Lung Disease
Bronchospasm.

6. Perioperative Pulmonary Physiology:-
Anaesthetic agent > Alterations in respiratory drive > Diminished
response to hypercapnia and hypoxemia > NM blocker > Diaphragm and
chest wall relaxation > Decreased Functional reserve capacity >
Decreased lung volume promotes atelectasis in the dependent lung regions
> V-Q mismatching and increased shunt fraction > arterial hypoxemia.

8. Thoracic and upper abdominal surgery:-
Is associated with a reduction in vital capacity by 50% and in functional
residual capacity by 30%. Diaphragmatic dysfunction, postoperative pain,
and splinting cause these changes.
Following upper abdominal and thoracic surgery, patients maintain
adequate minute volume, but the tidal volume is smaller and the
respiratory rate increases.

9. These breathing patterns, along with the residual effects of anesthesia and
postoperative narcotics
> inhibit cough > impair muco-ciliary clearance
> atelectasis.
contribute to the risk of postoperative pneumonia.

11. Patient related Risk Factors:-
Age:- >50 years is an independent risk factor.
This conclusion is controversial, as several other studies have shown
that age is not a predictor for postoperative pulmonary complications.
As age is obviously a nonmodifiable risk factor, and the potential risk
of complications does not invariably translate into increased mortality,
surgery should not be declined because of advanced age alone.

12. Obesity:-
Reduction in lung volume > ventilation-perfusion mismatch > relative
hypoxemia, which are accentuated after surgery.
In severe cases, obesity is associated with pulmonary hypertension, cor
pulmonale, and hypercapnic respiratory failure.
Some studies suggest that obesity increases the risk of PPC, others suggest
that obesity is not an independent risk factor.

13. General health status:-
The ASA classification and the Goldman Cardiac Risk Index successfully predict
pulmonary risk.
Arozullah respiratory failure index,
Canet risk index, Gupta calculator for PPC
Each of these systems has potential limitations.
Patients who have poor exercise capacity are at increased risk of developing
postoperative pulmonary complications

15. COPD:-
Patients with severe COPD (forced expiratory volume in 1 s [FEV1] < 40%
predicted) are 6 times more likely to have a major PPC.
Similarly, an FEV1 < 60% predicted was found to be an independent predictor of
increased mortality in patients undergoing coronary artery bypass graft (CABG)
procedures.

17. The benefits of surgery must be weighed against these complications.
A careful preoperative evaluation of patients with COPD should include
identification of high-risk patients and aggressive treatment.
Elective surgery should be deferred in patients who are symptomatic, have
poor exercise capacity, or have acute exacerbation.

18. Asthma:-
Asthma increases the risk of:-
Bronchospasm
Hypoxemia
Hypercapnia
Inadequate cough
Atelectasis
Pulmonary infection following surgery.
Well-controlled asthma does not increase risk of these complications.
Optimal asthma control is defined as the absence of symptoms and a forced
expiratory volume in 1 second (FEV1) of greater than 80% of predicted or personal
best.

20. Pulmonary hypertension:-
Increased risk of-----
Congestive heart failure
Hemodynamic instability
Sepsis
Respiratory failure
Longer ICU and hospital stay
Increased readmission rates
Worst outcomes documented CABG

21. Sleep apnoea:-
Obstructive sleep apnoea is present in 3-5% of the general population, and the
prevalence among surgical patients is likely significantly higher.
Patients with sleep apnoea are at increased risk of developing deterioration of
sleep-disordered breathing, severe hypoxemia, and hypercapnia in the
postoperative period.
It increases the risk of perioperative complications including hypoxia, acute
respiratory distress syndrome, and pulmonary embolism pneumonia, difficult
intubation, unplanned inpatient and intensive care admissions, myocardial
infarction and increased length of hospital stay.

22. Medications used for general anaesthesia (induction and maintenance),sedation and
analgesia will all increase the pathology underlying OSA.
This appears to be due to decreased upper airway dilatory activity (propofol and
inhalation agents)
it can also decrease the arousal response to airway obstruction and respiratory
depression (benzodiazepines, opioids).
There is also sleep disruption associated with the immediate postoperative period
with an absence of REM sleep for 1-2 nights after surgery.

23. Immunosuppression:-
Chronic steroid use is associated with an increased risk of postoperative
pneumonia.
Daily use of alcohol within 2 weeks of surgery is associated with an increased risk
of postoperative pneumonia and respiratory failure.
Insulin-treated diabetes is associated with an increased risk of postoperative
respiratory failure

24. Metabolic abnormalities
The presence of low serum albumin, elevated BUN, and low haemoglobin increases
the risk of POPC.
However, there is no clear evidence to prove that pre-operative correction of these
factors will reduce POPC.

25. Procedure-Related Risk Factors:-
The incidence of postoperative pulmonary complications is inversely related to the
distance of the surgical incision from the diaphragm.
Upper abdominal surgery: 17% to 76%.
For lower abdominal surgery: 0-5%.
For thoracic surgery, the rate is 19-59%.
Abdominal aortic aneurysm repair has highest risk of PPC.

26. Thoracic and upper abdominal surgeries :-reduction in vital capacity by 50% and in
functional residual capacity by 30%.
Duration of surgery-
Procedures longer than 3-4 hours:- 40% PPC
Shorter than 2 hours :- 8% PPC
Type of anaesthesia
General anaesthesia has more risk than Spinal or Epidural

27. Preoperative Risk Assessment:-
Complete history and perform a complete physical examination
PFT:-
On studies pulmonary function test (PFT) results found only a marginal benefit in
predicting postoperative complications in patients, other than those undergoing
lung resection.
Should be restricted to those patients with unexplained dyspnea or exercise
intolerance.
Flow volume loops, can be helpful in anaesthesia planning. They allow evaluation
of airway obstruction as well as differentiating between fixed and variable (intra-
and extra thoracic) obstruction to air flow. These can be helpful in the workup of
patients undergoing thyroid surgeries,unexplained dyspnoea, stridor, suspected
tracheal stenosis and vocal cord pathology.

28. ABG:-
Systematic review suggested that arterial blood gas results are not independently
predictive of complications.
Presumably patients with hypercapnia may be identified as high-risk on the basis
of other criteria.

29. Chest X-ray:-
The recommendation from the Guidelines Association Committee that routine chest
x-rays should not be performed routinely for preoperative evaluation in patients
without risk factors.
As on studies it is found that PPC risk is same for those undergoing CXR before
surgery.

30. Preparation for Surgery:-
Smoking cessation:-
Current smoker are at 2-fold increased risk of PPC. even in the absence of COPD.
Small airway disease may not be picked up on spirometry, require at least 2 month
to improve after smoking cessation.
Hypersecretion mucus may take 6 weeks to decline.

31. Reduced tracheobronchial clearance may take months to get normalised.
Depressed immune system take about 1 week to become normal.
Reduced immunoregulatory T-cell activity takes 6 weeks to improve.
I/V/O above factors at least 6-8 weeks abstinence Is necessary to reduce risk of
PPC.

32. If not possible at least 12-24 hrs of abstinence is necessary to reduce
cardiac morbidity (IHD)
Patients who quit smoking for more than 6 months have a risk similar to
those who do not smoke.
Although the risk of postoperative pneumonia appears to remain elevated
up to 1 year after smoking cessation.

33. Asthma control:-
Optimize asthma control before surgery.
If FEV1 < 80% of personal best- brief course of corticosteroid should be given.
If systemic corticosteroids received for >3 weeks in last 6 months Hypothalamic-
pituitary-adrenal axis suppression should be assumed to be present.

34. These patients should receive stress-dose coverage perioperatively, hydrocortisone
100 mg IV q8h, with rapid tapering after 24 h.
Nebulisation with Salbutamol & Ipratropium Bromide (5mg+500mcg) 6 hourly
perioperatively.
Adrenaline (0.3 ml of 1:1000) may be helpful in acute bronchospasm.

35. COPD:-
FEV1/FVC <50%, maximum voluntary ventilation <50%, & high PaCO2 have
high risk.
Bronchodilators, smoking cessation, antibiotics, chest physical therapy, deep
breathing exercises, incentive spirometry & CPAP before and after surgery
prevent atelectasis.

36. Preoperative antibiotics:-
Prophylactic antibiotics does not lead to a reduction in pulmonary complications.
These drugs may be used in patients with a clinically apparent respiratory infection.
Cancel elective surgery if the patient has an active infection.
Inspiratory muscle training:-
Particularly in abdominal aortic aneurysm (AAA) repair and CABG prevent atelectasis.
Pulmonary rehabilitation in high risk patients.

37. Summary:-
High risk patients:
Smoking cessation
Antibiotics for acute bronchitis
Optimize COPD and asthma treatment regimens - Course of systemic steroids if
suboptimal control
Educate patients on lung expansion maneuvers
Consider inspiratory muscle training or pulmonary rehabilitation in high-risk
patients

38. Intraoperative Strategies:-
Type of anaesthesia:-
Intermediate- and shorter-acting agents are preferred, because residual
neuromuscular blockade from longer-acting agents may contribute to pulmonary
complications.
Spinal or epidural anaesthesia in combination with general anaesthesia is
associated with less postoperative respiratory depression.
Shorter procedure should be considered in extremely high-risk patients, also
laparoscopic procedures are preferred over open surgeries if possible.

39. Postoperative Strategies:-
Lung expansion maneuvers include:- incentive spirometry, deep breathing
exercises, postural drainage, percussion and vibration, cough, suctioning,
mobilization, intermittent positive pressure breathing (IPPB), and CPAP.
Studies suggest that CPAP is the most effective lung expansion maneuver.
A notable benefit of this modality is that it does not require patient
cooperation or effort.

40. Adequate postoperative pain control:-
Helps minimize pulmonary complications by encouraging earlier ambulation and
performance of lung expansion maneuvers.
Intrathecal administration of narcotics is associated with a longer duration of
analgesia, respiratory depression, and headaches.

41. Intercostal nerve blocks shown to be beneficial in upper abdominal as well as
thoracic surgery.
Paravertebral blocks may be associated with fewer pulmonary complications than
epidural analgesia
Epidural narcotics provide a longer duration of action, a lack of excessive sedation
and respiratory depression, and a minimum or no sensory motor loss.
Nasogastric decompression
Routine use of nasogastric tubes until bowel function returns following abdominal
surgery is associated with higher rates of pneumonia and atelectasis than ---->
selective use of nasogastric tubes in patients who develop postoperative nausea or
vomiting, inability to tolerate oral intake, or symptomatic abdominal distention

42. Prevention of thromboembolism:-
Patients age >40 years
Surgery time >30 min
are at increased risk of PTE
Advice including passive leg exercises should be given.

44. Thank You