Lung protective strategies in Cardiothoracic Surgery

1. Dr . S.K. VARMA
KG Hospital ,Coimbatore

3. IMPROVE Trial

7. Heart, Lung and Vessels. 2015; 7(1): 5-6

8. Postop Pulmonary Complications

11. 300,000 patients who undergo cardiac surgery
every year in the United States, as many as 20% will have
ARDS [4 –9]. The mortality associated with ARDS approaches
40% in the general population, but among
post–cardiac surgery patients, mortality may be as high
as 80%
Ann Thorac Surg 2013;95;1122-9

12. Increased risk of ARDS
 Aortic surgery
 Pulmonary Endarterectomy
 Lung Transplantation
 Emergent surgery

15. Use of Lower Tidal Volumes
Benefits Patients with ARDS
ARDS Network. N Engl J Med. 2000;
342:1301

16. Definition
Fatal or nonfatal respiratory events of new onset
occuring in the postoperative period withiin 5-7 days
of surgery.

17. PPC
 Respiratory failure
 Pneumonia
 Prolonged or unplanned mechanical ventilation
 Atelectasis
 Pleural effusion
 Pneumothorax
 Aspiration pneumonitis

18. Risk factors for PPC

19. Pathogenetic mechanisms of PPC
 Specific to cardiac surgery:
(i) Median sternotomy incision
(ii) Use of cardiopulmonary bypass (CPB)
(iii) Transfusion of blood product
(iv) Topical cooling for myocardial protection
(v) Dissection of the internal mammary artery
(vi) Effects of general anesthesia

20. Pathogenetic mechanisms contd
 Anomalies in gas exchange:
(i) Widening of the alveolar-arterial oxygen gradient
(ii) Increased microvascular permeability in the lung
(iii ) Increased pulmonary vascular resistance
(iv) Increased pulmonary shunt fraction
(v) Intrapulmonary aggregation of leukocytes and
platelets

21. Pathogenetic mechanism contd Alterations in lung mechanics:
(I) Reductions in vital capacity (VC)
(ii) Reduction of functional residual capacity (FRC)
(iii) Reduction of static and dynamic lung compliance

22. Prediction of PPC
 ARISCAT SCORING
 RESPIRATORY FAILURE RISK INDEX
 LUNG INJURY PREDICTION SCORE
 SURGICAL LUNG INJURY PREDICTION

23. Pathophysiology of VILI

25. One more point: VILI is more than
a lung injury
 Cytokines released into circulation cause other organ
failures
 Lung barrier function to bacteria broken
ALI/ARDS patients do NOT die from respiratory failure
– they die of multi-organ failure and sepsis
 ARDS Net mortality benefit accompanied by lower
cytokine levels and fewer organ failures

26. Is mechanical ventilation a double
edged sword?

27. Lung Protective Ventilator
Strategies
 What are we protecting the lung from?
 What are “conventional” strategies to provide
protection?
 What are new strategies to provide protection

29. ATELECTASIS
 90% Patients
 Mechanisms
1. Collapse of small airways
2. Compressions of lung structures
3. Absorption of intra alveolar gas content
4. Impairment of surfactant function
 Aim is to increase End Expiratory Volume

30. Lung protective ventilation
 Low tidal volume
 PEEP
 Recruitment maneuvres
 Prevent Hyperoxia
 Limit Plateau pressure
 Reduce respiratory driving pressure

31. Open Lung Approach
Aim is to decrease the respiratory driving pressure or
delta pressure (Pplateau- PEEP)

37. GOO
D
BAD

38. Recruitment maneuvers

39. De-recruitment can occur due to:
 low tidal volume (TV) ventilation
 inadequate postive end-expiratory pressure (PEEP)
 or use of high FiO2 (absorption atelectasis)

40. Advantages
Recruitment manoeuvres are used to open up
collapsed lung, and PEEP is used to prevent cyclic
collapse as part of OLA ventilation to
 increase end-expiratory lung volume
 improve gas exchange
 decrease VILI

41. Disadvantages
 benefit may be transient
 haemodynamic instability (decrease in preload)
 hypercapnia
 may worsen oxygenation by shunting blood to poorly
aerated regions
 may contribute to ventilator-induced lung injury
(VILI) due to overdistension and repeated opening of
lung
 risk of pneumothorax

42. Recruitment maneuvres
 Recruitment maneuvres are transient increases in
transpulmonary pressure designed to open up
collapsed airless alveoli
 Primarily used in severe acute respiratory distress
syndrome (ARDS)
 They can be used as part of an open lung approach
(OLA) to mechanical ventilation

43. Serpa Neto A. JAMA
2012; 308:1651

44. Higher Tidal Volumes and Organ Dysfunction after Cardiac
Surgery
Lellouche F. Anesthesiology 2012; 116:1072

45. Cuppola et al ‘Protective lung ventilation during general anaestheisia:Is
there any evidence ‘ Critical care 2014 18:210

46. Peri-operative VILI
Normal lungs - small VT reduces post-op respiratory
complications:
 Chest 2011;139:530-7
 J Cardiothor and Vasc Anesth. 2010; 24:681-90
 Anesthesiol. 2006; 105:14-8
 J Cardiothor Vasc Anesth. 2000;14:514-8
Donor lungs for transplant – small VT doubles viability
 JAMA 2010;304:2620

50. RCT using non clinical primary
outcome
 11 RCT
 Thoracic -5 Cardiac -3 Abdominal -3
 8 RCT low Vt and High PEEP
 2 RCT either low Vt or High PEEP
 1 RCT lung recruitment manuevers used
 RESULTS – 6 RCTs showed significant decrease in the
inflammatory mediators
Guldner et al “ Intraoperative protective mechanical vetilation for
prevention of postoperative pumonary comlications A
comprehensive review of the role of tidal volume , PEEP and Lung
recruitment maneuvers “Anesthesiology 2015 ;123:692-713

51. Non clinical outcome measures
 Measurement of various inflammatory biomarkers
interleukin, TNF alpha both in Brochioalveolar lavage
and plasma
 PaO2/FiO2 ratio
 PaCo2
 Lung Compliance
 Pulmonary function test

52. RCT using clinical primary outcome
 Eight RCTs
 Thoracic -2,Cardiac-1,Abdominal-4,Spinal-1
 4 Trials reported reduction in PPCs in Protective
ventilation group
Guldner et al “ Intraoperative protective mechanical
vetilation for prevention of postoperative pumonary
comlications A comprehensive review of the role of tidal
volume , PEEP and Lung recruitment maneuvers
“Anesthesiology 2015 ;123:692-713

53. Clinical outcome measures
 Development of PPC like atelectasis ,pneumonia,need
for invasive/noninvasive ventilation for acute
respitaory failure etc
 Length of stay in ICU and in the hospital
 Mortality

54. IMPROVE STUDY Intraoperative
PROtective VEntilation
 French multicentre trial
 400 non obese patients undergoing abdominal
surgery
 PV group 6-8ml/kg Vt PEEP 6-8cm H2O and RM
 NPV 10-12ml/kg with no PEEP and no RM
Futier et al ‘A trial of intra operative low tidal volume
ventilation in abdominal surgery’ N.Eng.J.Med (2013) 369:5
428-37

55. Improve Study (Contd)
 Primary Outcome –pulmonary (pneumonia and acute
respiratory failure)and extrapulmonary complications (sepsis)
 Secondary outcome –Duration of ICU and hospital stay and
30days mortality after surgery
Results
Primary outcome - incidence of pulm and extrapulm complications
 PV group 10.5% NPV group 27.5% ( P =0.001)
Secondary outcome
 Postop noninvasive ventilation and reintubation less in PV group
(P =0.001)
 Shorter length of ICU stay (P=0.006)
 Mortality unaffected