one lung ventilation related physiology ,different situation and their perspectives

1. ONE LUNG
VENTILATION
PRESENTOR : DR.NANDHINI.N
MODERATOR : DR.VIRENDRA KUMAR

2. CONTENTS
 Introduction of OLV
 Advantages of OLV
 Indications of OLV
 Ventilation-Perfusion
 Variants of Lateral Decubitus Position
 Hypoxic pulmonary vasoconstriction
 Hypoxia-Causes
 Hypoxia-Management

3. INTRODUCTION
A technique that allows isolation of the
individual lungs under anesthesia
one lung for the surgeon
one lung for the anesthetist
GALES and WATERS - use of selective
lung Ventilation during thoracic surgeries
in 1931.

4. ADVANTAGES
• Independent channel – ventilation
• Isolation of normal lung from diseased:
Preventing contamination by infected
secretions & mucous materials.
• Independent collapse of lung to be operated
and re-expansion when needed.

5. Provides optimal operating condition :
Facilitating easy approach; retraction of
affected area with minimal stretching & trauma
to tissues
Bloodless field & shortens duration of surgery
Complete collapse of lung facilitates other
surgeries

6. INDICATIONS OF OLV

7. ABSOLUTE
1) To avoid spillage / contamination
 Infection
 Massive hemorrhage
2) U/L Broncho-pulmonary lavage
3) Video-assisted thoracoscopic
surgery (VATS)

8. 4) Control-distribution of ventilation
 Broncho-pleural/cutaneous fistula
 Surgical opening of major conducting
airways
 Giant U/L lung cyst/bulla
 Tracheo-bronchial tree disruption
 Life-threatening hypoxemia

9. RELATIVE
1)Surgical exposure
High Priority :
 Thoracic aortic aneurysm
 Pneumonectomy
 Upper lobectomy
 Mediastinal exposure
 Thoracoscopy

10. Low priority :
 Middle & lower lobectomies and
sub-segmental resections
 Esophageal surgery
 Thoracic spine procedure
 Minimally invasive cardiac surgery

11. 2) Post cardiopulmonary bypass status
-after removal of totally occluding
chronic unilateral pulmonary emboli.
3) severe hypoxemia
-due to unilateral lung disease.

12. PHYSIOLOGY
 Distribution of perfusion
 Distribution of ventilation
 Ventilation-Perfusion Ratio

13. PERFUSION
 In Lateral decubitus position (LDP):
 PBF-uneven due to effect of gravity
 Decrease linearly from base to apex
 In supine,
 BF almost evenly distributed
Apical BF - increases
 Basal BF - virtually unchanged

14. DISTRIBUTION OF PERFUSION
IN UPRIGHT :

15. • LDP :
-Similar to that in upright position

16. VENTILATION
REST INSPIRATION
EXPIRATION

17. DISTRIBUTION OF ALVEOLI

18. PRESSURE-VOLUME CURVE

19. VENTILATION
At the start of inspiration ,
The apex of the lung remains in more
expanded state
 Less compliant
 More stiff to expand
Ventilation per unit lung volume is greater at
the base of the lung than at the apex.

20. MATCHING OF VENTILATION-
PERFUSION
Matching is never ideal as :
V/Q gradients are not identical
Better :during spontaneous than during
positive pressure ventilation
 Alveolar pressure : increased
 PBF-less homogeneous (west zone)

21. V/Q RELATIONSHIP
ZONE 1 : (V) >>> (Q)
V/Q : 3.4 (High )
ZONE 2 : (V) = (Q)
V/Q : 0.8 (Average )
ZONE 3 : (Q) >>> (V)
V/Q : 0.63 (Low )

22. DEAD SPACE SHUNT
VENTILATION ✓ ✗
PERFUSION ✗ ✓
V/Q ∞ 

23. VARIANTS OF LATERAL
DECUBITUS POSITION
1) Awake/ B.Spont. / Closed Chest
2) Awake/ B.Spont. / Open Chest
3) Anaesthetized/ B.Spont. / Closed
4) Anesthetized/ B.Spont. / Open
5) Anesthetized/ Paralyzed/ Open Chest
6) Anesthetized/ Paralyzed/ Open Chest
-OLV

24. 1)AWAKE /B.SPONT./CHEST CLOSED
 VENTILATION
Dependent lung (DL) is better ventilated
than Non-dependent lung (NDL)
1) Abdominal contents pushes higher the
dependent hemidiaphragm into chest-
conserved ability to contract (+)
2) Dep.lung fall in more steeper (
favourable) part of compliance curve.

26. • PERFUSION : GRAVITY-DEPENDENT
Dependent lung better perfused
BF DL NDL
% C.O 60 40
SHUNT 5 5
TOTAL 55 35

27. 2)AWAKE/B.SPONT./CHEST OPEN
MEDIASTINAL SHIFT

28.  PARADOXICAL BREATHING
INSPIRATION : COLLAPSE OF EXP.LUNG
EXPIRATION : EXPANSION OF EXP.LUNG

29. 3)ANESTHETISED/B.SPONT./CHEST
CLOSED
Induction of GA / Cephalad displacement of
dep.diaphragm-by abdominal contents /Mediastinal
shift/Poor positioning

30. DL NDL
VENTILATION(
VT)
LESS MOST
PERFUSION GOOD
(GRAVITY)
LEAST
COMPLIANCE
CURVE
FLAT STEEPER
As a result : Leads to V/Q mismatch

31. 4)ANESTHETISED/B.SPONT/OPE
N CHEST
NDL-Highly compliant (increased compliance & pressure exerted by
abdominal contents againt hemidiaphragm is minimal)

32. DL NDL
 Poorly-Ventilated
 Over-Perfused
(Gravitational
effect)
 Relatively Non-
Compliant
 Over-Ventilated
 Under-Perfused
 Highly compliant (
no restriction of
chest wall & free to
expand)
Further increasing V/Q mismatch

33. 5)ANESTHETISED/PARALYSED/CHEST
OPEN
As pressure of abd.contents pressing
against NDL hemidiaphragm – Minimal
Easier for Positive pressure ventilation to
displace this less resisting dome of
diaphragm (increases compliance )
Further compromises ventilation to DL &
increases V/Q mismatch

34. 6)
OLV/ANESTHETISED/PARALYS
ED/CHEST OPEN
HPV

35. HYPOXIC PULMONARY
VASOCONSTRICTION
 Physiological local response of
pul.vascular SM to alveolar hypoxia
 Stimulus : PA02 – 4 to 8 kpa
 Stimulates : pre-capillary VC
 Re-distribution of PBF- away from
hypoxemic lung regions - via : K+ / Nitric
oxide / COX synthesis inhibitor pathway

36.  Minimizes the shunt fraction
 50% reduction in BF - NDL/NVL
 Maintains a normal V/Q relationship
Graded and limited (greatest benefit : 30%
to 70% of lung is hypoxic)
Effective only when normoxic areas (+)

37. FACTORS INHIBITING HPV

38. 6)ANESTHETISED/PARALYSED/CHE
ST OPEN
(40-5)
35%
(60-5)
55%
Bld.flw: by 50%
17.5%
77.5%
Shunt(5)
=22.5%
Rt-Lt shunt (+)
To Match (V):adequate gas exchange

39. Dependent lung :
No longer on the steep (compliant)
portion of curve
Reduced lung volume & FRC.
 Creates :
 Low V/Q ratio
 Large P(A-a) O2 gradient.

40. Greatest Risk of OLV :
HYPOXEMIA

41. HYPOXIA- CAUSES
 Induction of GA
 Mediastinal shift
 Pressure from abdominal contents
 Suboptimal positioning
 Transudation of fluid into DL
 Absorption atelectasis
 Accumulation of secretions

42.  Surgical interference
 Increased FIO2
 Mode of ventilation of dependent lung
 Malposition of DLT
 Failure of oxygen supply
 Gross hypoventilation of DL
 Resorption of residual O2 from clamped
lung

43. MANAGEMENT
If severe Desaturation :
Resume Double Lung Ventilation
(If possible )
If gradual Desaturation :
1) Use fio2 : 1
2) Ventilate : Vt -6–8 ml/kg
PEEP- 5 cm H2O
3) RR : to maintain PaCo2
( 35 and 40 mm Hg )

44. 4) Check DLT / endobronchial blocker
position - subsequent to LDP
5) If PAP : >40 cm H2O during OLV-DLT,
endobronchial blocker malposition should
be excluded.
6) Apply : CPAP -10 cm H2O –NDL
(most effective)

45. 8) Frequent recruiting maneuvers
9) Avoid fluid overload
10) TIVA - preferable to inhalation
anesthetics
11) If necessary : intermittently inflate and
deflate the operated lung

46. OTHERS
Ensure : Cardiac output is optimal
Volatile anesthetics to MAC < 1
Mechanical restriction of BF - NDL
Partial ventilation technique-NDL
O2 insufflation
Frequency of ventilation
 Lobar collapse (using B.Blocker)

47. THANK YOU