2. COPD is a disease of resistance during expiration
but
with the consequence of restriction during inspiration.
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
4. P-V curve of Lung, Chest wall and Respiratory system
Chest wall
Lung
TLC
Vital capacity %
100
Chest wall and Lung
( respiratory system)
75
50
25
FRC
RV
0
-20
0
20
Pressure ( cm H2O)
Ppl, Pcw, Prs
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
5. Resting Volume of Respiratory system
Elastic force of LUNG
=
Elastic force of CHEST WALL
At End Expiration
Functional Residual Capacity
(FRC)
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
15. Beginning of passive expiration
0
TPP = PA – Ppl
Ppl = -5
-5
-5
+7 = PA– (-5)
PA = +2
+2
-5
-5
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
16. Mid expiration
0
TPP = PA – Ppl
PA = +1
-5
-5
TPP = +1– (-5)
PA = +6
+1
-5
-5
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
17. End expiration
0
TPP = PA – Ppl
PA = 0
-5
-5
TPP = 0– (-5)
TPP = +5
0
-5
-5
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
18. In healthy lung during normal tidal respiration
Throughout the respiratory cycle
TPP and TAP remains positive
keeping the alveoli and airways
patent
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
21. Equal Pressure Point ( EPP)
Point in airway where TAP is zero during expiration
Dynamic Airway Collapse
Point in airway distal to EPP, TAP becomes negative,
causing airway to collapse
No amount of effort will increase the expiratory flow
Expiratory Flow limitation
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
22. Counter balance of Dynamic Airway Collapse
First 11 generation of airway ( bronchi)
supported by cartilage ring/ plates
12th generation and beyond ( bronchioles)
supported by tethering effect of elastic recoil of surrounding lung parenchyma
Patency of airways is a function of
cartilagenous support in bronchi
Lung volume in bronchioles
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
23. Equal Pressure Point
Dynamic point
As airway resistance increases
or
Lung volume decreases
Moves closer to Alveoli
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
25. Expiratory Flow Limitation
can be a manifestation of
Airway disease
COPD, Asthma
Destruction of cartilage of airway
Lung parenchyma disease
leading to reduced lung volume
collapse, lung destruction, pneumonectomy
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
26. IN HEALTHY LUNG
During quiet breathing
There is no dynamic airway collapse
No expiratory flow limitation
During forced expiration
Small degree of dynamic airway collapse can occur
(Upto 40% reduction in cross sectional area of airway)
Because of invagination of posterior membrane of tracheo bronchial tree
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
27. Dynamic airway collapse during Coughing
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
28. Flow and Time Relationship
Of
Respiratory system
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
29. Concept of
Closing Volume & Closing Capacity
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
30. Effect of gravity
+
weight of lung
Vertical gradient
in
Ppl and TTP
Dependent alveoli have lesser volume
than non dependent alveoli
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
31. PLEURAL PRESSURE AND TPP GRADIENT
(At FRC)
BODY
POSITION
TOP OF
LUNG
BOTTOM OF
LUNG
Ppl
TPP
Ppl
TPP
UPRIGHT
-8
8
-2
2
SUPINE
-4
4
0
0
PRONE
-3.5
3.5
0
0
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
32. P- V curve of Respiratory system at different Lung volumes
VERTICAL GRANIDIENT
FRC
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
33. P- V curve of Respiratory system at different Lung volumes
VERTICAL GRANIDIENT
TLC
RV
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
34. IN HEALTHY LUNG
During forced expiration
Dynamic airway collapse occurs
starting from dependent lung regions
Critical volume of lung during expiration to prevent dynamic airway collapse
CLOSING CAPACITY
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
35. CLOSING CAPACITY
5.0
TLC
In healthy lung
44 years
CC= FRC in supine position
3.0
2.5
1.25
CC
66 years
CC = FRC in upright position
FRC
CC
RV
Smoking, ageing, obesity,
supine position
Increases CC
0
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
36. Effect of PEEP on CLOSING CAPACITY
5.0
TLC
PEEP
3.0
CC
2.5
FRC
1.25
RV
0
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
37. TIME CONSTANT
length of time required to fill or empty lung units
Function of
Alveoli = compliance
Airway= resistance
TC = C
R
1 TC = 63% of lung unit fill/ empty
3 TC = 95%
“
“
“
5 TC = 99%
“
“ “
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
40. Increased Airway Resistance
dynamic airway collapse
Expiratory Flow Limitation
Air Trapping
Increased End Expiratory Lung Volume ( EELV)
DYNAMIC HYPERINFLATION
(DHI)
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
41. v
FRC
T
DHI is probably an adaptive response to overcome DAC
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
42. Initially DHI
Increases elastic recoil of lung ---- opens airway---- improves expiratory flow
But
Comes
At
price
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
43. P-V CURVE OF RESPIRATORY SYSTEM
Healthy lung- tidal ventilation
V
TLC
IRV
IC
TV
FRC
ERV
RV
P
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
44. P-V CURVE OF RESPIRATORY SYSTEM
Healthy lung - exercise
V
TLC
IRV
IC
TV
FRV
ERV
RV
P
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
45. P-V CURVE OF RESPIRATORY SYSTEM
Chronic obstructive airway disease- tidal breathing
V
TLC
IRV
IC
TV
EELV
RV
P
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
46. P-V CURVE OF RESPIRATORY SYSTEM
Chronic obstructive airway disease- exacerbation
V
TLC
IRV
IC
EELV
EELV
RV
P
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
47. EFFECT ON GAS EXCHANGE
Increased EELV
More Zone I and II formation
Increased dead space
V/Q mismatch
Increased minute ventilation requirement
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
48. EFFECT ON DYNAMIC MECHANICS
Displacement of respiratory system towards upper flatter portion of P-V curve
P-
Altered geometry of the chest wall
Flattened and lowered diaphragm, more horizontal rib cage
Respiratory muscles operating at higher lung volumes
Increased elastic loading of inspiratory muscles at end expiration
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
49. EFFECT ON DYNAMIC MECHANICS
Before starting inspiratory flow must overcome this increased elastic load
Effort required to generate tidal volume is more than the muscle can
generate at that lung volume
Expiratory muscles axis of contraction is altered
paradoxical indrawing of lower ribs– hoover sign
ribs–
•Decreased ventilatory capacity
•Functional muscle weakness and fatigue
•Increased WOB
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
50. EFFECT ON HEMODYNAMICS
Increased EELV
Increased ventilatory drive
Increased TPP
More negative pleural pressure
↓ preload and ↑ afterload of RV
↑ RV preload in face of ↑ RV afterload
Series ventriclular interdependence
Parallel ventricular interdependence
↓ LV stroke volume
LV filing compromised
Hypotension
LV dysfunction and failure
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
51. EFFECT ON PATIENT
Increased
ventilatory drive
Increased
WOB
anxiety
Neuromechanical
discoupling
VQ mismatch
Worsening
hemodynamics
Neural drive= Increased RR = decreased expiratory time
Expiratory flow limitation = need for increased expiratory time
dyspnoea
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
54. CORRECTION OF GAS EXCHANGE
REDUCTION OF WOB
CORRECTION OF
LUNG MECHANICS
TREATMENT OF BASELINE DISEASE
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
55. CORRECTION OF LUNG MECHANICS
Prevention of DHI
Reduce airway resistance
Treatment of disease
PPV
PEEP
•Easy Inspiratory flow
•Prevention of DAC
PPV
Adequate expiratory time
Neuro muscular recoupling
sedation,anti anxiety
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
60. Setting total cycle time
Flow rise
cycling
Calculation of expiratory time
Calculation of TCT
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
61. the difficulty lies, not in new ideas,
but escaping old ones,
which ramify, for those brought up with them,
as most of us have been, into every corner of our minds.
- John Maynard Keynes
Thank you
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
