expiratory flow limitation_diseases
TRANSCRIPT
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COPD is a disease of resistance during expiration
but
with the consequence of restriction during inspiration.
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Pressure Volume relationshipof of
respiratory system
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
50
75
100
Chest wallLung
Chest wall and Lung( respiratory system)
Vita
l cap
acity
%
TLC
P-V curve of Lung, Chest wall and Respiratory system
0
25
50
0-20 20
FRCRV
Pressure ( cm H2O)Ppl, Pcw, Prs
Vita
l cap
acity
%
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Resting Volume of Respiratory system
At End Expiration
Elastic force of LUNG Elastic force of CHEST WALL=
Functional Residual Capacity(FRC)
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
5.0
2.5
3.0
IRVIC
VC
TLCTV
LUNG VOLUMES
0
2.5
1.25
TLC
RV
ERV
FRC
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Pressure, Volume and Flow relationship
of Respiratory system
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Relationship between intrathoracic pressures
TPP = PA – Ppl
TPP = Transpulmonary PressurePA = Alveolar PressurePpl = Pleural PressurePel = lung elastic recoil pressure
PA = Ppl + Pel
TPP = (Ppl + Pel) – (Ppl) = Pel
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Relationship between intrathoracic pressures
TAP = Paw – PplTAP = Paw – Ppl
TAP = Transairway PressurePaw = airway pressurePpl = Pleural Pressure
TPP
TAP Paw
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
-5 -5
0
End expiration
PA = 0
TPP = PA – Ppl
0
-5-5
Ppl = -5
TPP = 0 – (-5) = +5
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
-7 -7
0
Beginning of inspiration
TPP = PA – Ppl
Ppl = -7
+5 = PA – (-7)
-2
-7-7
+5 = PA – (-7)
PA = +5 – 7 = -2
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
-7 -7
0
Mid inspiration
-1
-7-7
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
-7 -7
0
End inspiration
TPP = PA – Ppl
Ppl = -7
TPP = 0 – (-7)
0
-7-7
TPP = 0 – (-7)
TPP= +7
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
-5 -5
0
Beginning of passive expiration
TPP = PA – Ppl
Ppl = -5
+7 = PA– (-5)
+2
-5-5
+7 = PA– (-5)
PA = +2
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
-5 -5
0
Mid expiration
TPP = PA – Ppl
PA = +1
TPP = +1– (-5)
+1
-5-5
TPP = +1– (-5)
PA = +6
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
-5 -5
0
End expiration
TPP = PA – Ppl
PA = 0
TPP = 0– (-5)
0
-5-5
TPP = 0– (-5)
TPP = +5
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
TPP and TAP remains positiveTPP and TAP remains positive
Throughout the respiratory cycleThroughout the respiratory cycle
In healthy lung during normal tidal respirationIn healthy lung during normal tidal respiration
keeping the alveoli and airwayskeeping the alveoli and airwayspatentpatent
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
+10 +10
0
Beginning of forced expiration
TPP = PA – Ppl
Ppl = +10
+7 = P – (+10))
+10
+8
+6
+4
+2
+17
+10+10
+7 = PA– (+10))
PA = +17 +15
+13
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
+10 +10
0
forced expiration
+10
+8
+6
+4
+2
TAP = Paw – Pp
TAP = (+10) – ( +10) = 0
+17
+10 +10
+15
+13
Dynamic airway Collapse ( DAC)
Expiratory Flow Limitation
Equal Pressure Point ( EPP)
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
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
First 11 generation of airway ( bronchi)supported by cartilage ring/ plates
Counter balance of Dynamic Airway Collapse
12th generation and beyond ( bronchioles)supported by tethering effect of elastic recoil of surrounding lung parenchyma
cartilagenous support in bronchi
Lung volume in bronchioles
Patency of airways is a function of
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Equal Pressure Point
Dynamic point
As airway resistance increases or
Lung volume decreasesMoves closer to Alveoli
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
+10 +10
0
+10
+8
+6
+4+2
+2
+4
+6
+10 +10
0
FORCED EXPIRATION
+17
+10 +10
+15
+13
Beginning of forced expiration
+10 +10
+12
+10
Mid forced expiration
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Airway disease
COPD, Asthma
Destruction of cartilage of airway
can be a manifestation of
Expiratory Flow Limitation
Lung parenchyma disease leading to reduced lung volume
collapse, lung destruction, pneumonectomy
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
There is no dynamic airway collapse
No expiratory flow limitation
IN HEALTHY LUNG
During quiet breathing
Because of invagination of posterior membrane of tracheo bronchial tree
During forced expiration
Small degree of dynamic airway collapse can occur
(Upto 40% reduction in cross sectional area of airway)
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Dynamic airway collapse during Coughing
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Flow and Time Relationship Of
Respiratory system
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Concept of Closing Volume & Closing CapacityClosing Volume & Closing Capacity
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Effect of gravity+
weight of lung
Vertical gradientinin
Ppl and TTP
Dependent alveoli have lesser volumethan non dependent alveoli
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
PLEURAL PRESSURE AND TPP GRADIENT(At FRC)
BODYPOSITION
TOP OF LUNG
BOTTOM OF LUNG
Ppl TPP Ppl TPP
-8 8 -2 2UPRIGHT -8 8 -2 2
SUPINE -4 4 0 0
PRONE -3.5 3.5 0 0
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
P- V curve of Respiratory system at different Lung volumesVERTICAL GRANIDIENT
FRC
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
TLC
P- V curve of Respiratory system at different Lung volumesVERTICAL GRANIDIENT
RV
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
IN HEALTHY LUNG
During forced expiration
Dynamic airway collapse occursstarting from dependent lung regions
Critical volume of lung during expiration to prevent dynamic airway collapseCLOSING CAPACITY
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
5.0
2.5
3.0
CLOSING CAPACITY
TLC
In healthy lung44 years
CC= FRC in supine position
66 yearsCC = FRC in upright positionCC
0
2.5
1.25RV
CC
FRC
Smoking, ageing, obesity, supine position Increases CC
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
5.0
2.5
3.0
Effect of PEEP on CLOSING CAPACITY
CC
TLC
PEEP
0
2.5
1.25RV
FRC
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
TIME CONSTANT
length of time required to fill or empty lung unitslength of time required to fill or empty lung units
Alveoli = compliance
Function of
Airway= resistance
TC = C � R
1 TC = 63% of lung unit fill/ empty3 TC = 95% “ “ “ 5 TC = 99% “ “ “
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
normal
Decreased compliance
Increased resistance
TC ↓
TC ↑
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Obstructive Airway DiseaseObstructive Airway Disease
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Increased Airway Resistance
dynamic airway collapsedynamic airway collapse
Expiratory Flow LimitationExpiratory Flow Limitation
Air Trapping Air Trapping
DYNAMIC HYPERINFLATION(DHI)
Increased End Expiratory Lung Volume ( EELV)
Air Trapping Air Trapping
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
v
T
FRC
DHI is probably an adaptive response to overcome DAC
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Increases elastic recoil of lung ---- opens airway---- improves expiratory flow
Initially DHI
Increases elastic recoil of lung ---- opens airway---- improves expiratory flow
But Comes
At price
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
V
TLC
TV
IRV
IC
P-V CURVE OF RESPIRATORY SYSTEMHealthy lung- tidal ventilation
P
RV
FRC
TV
ERV
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
V
TLC
TV
IRV
IC
P-V CURVE OF RESPIRATORY SYSTEMHealthy lung - exercise
P
RV
FRV
TV
ERV
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
V
TLC
TV
IRV
IC
P-V CURVE OF RESPIRATORY SYSTEMChronic obstructive airway disease- tidal breathing
P
RV
EELV
TV
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
V
TLC
IC
EELV
IRV
P-V CURVE OF RESPIRATORY SYSTEMChronic obstructive airway disease- exacerbation
P
RV
EELV
EELV
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Increased EELVIncreased EELV
More Zone I and II formationMore Zone I and II formation
Increased dead spaceIncreased dead space
EFFECT ON GAS EXCHANGE
V/Q mismatch
Increased minute ventilation requirement
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Displacement of respiratory system towards upper flatter portion of PDisplacement of respiratory system towards upper flatter portion of P--V curveV curve
Altered geometry of the chest wall Altered geometry of the chest wall Flattened and lowered diaphragm, more horizontal rib cageFlattened and lowered diaphragm, more horizontal rib cage
EFFECT ON DYNAMIC MECHANICS
Respiratory muscles operating at higher lung volumesRespiratory muscles operating at higher lung volumes
Increased elastic loading of inspiratory muscles at end expirationIncreased elastic loading of inspiratory muscles at end expiration
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Expiratory muscles axis of contraction is alteredExpiratory muscles axis of contraction is altered
EFFECT ON DYNAMIC MECHANICS
Before starting inspiratory flow must overcome this increased elastic loadBefore starting inspiratory flow must overcome this increased elastic loadEffort required to generate tidal volume is more than the muscle can Effort required to generate tidal volume is more than the muscle can
generate at that lung volumegenerate at that lung volume
Expiratory muscles axis of contraction is alteredExpiratory muscles axis of contraction is alteredparadoxical indrawing of lower ribsparadoxical indrawing of lower ribs–– hoover signhoover sign
•Decreased ventilatory capacity•Functional muscle weakness and fatigue
•Increased WOB
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Increased EELVIncreased EELV
Increased TPPIncreased TPP
↓↓ preload and preload and ↑↑ afterload of RVafterload of RV
Increased ventilatory driveIncreased ventilatory drive
More negative pleural pressureMore negative pleural pressure
↑↑ RV preload in face of RV preload in face of ↑↑ RV afterloadRV afterload
EFFECT ON HEMODYNAMICS
Series ventriclular interdependenceSeries ventriclular interdependence
↓↓ LV stroke volume
Hypotension
Parallel ventricular interdependence
LV filing compromised
LV dysfunction and failure
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Increased Increased ventilatory driveventilatory drive
EFFECT ON PATIENT
anxietyanxiety
Worsening Worsening hemodynamicshemodynamics
IncreasedIncreasedWOBWOB
Neuromechanical Neuromechanical discouplingdiscoupling
VQ mismatchVQ mismatch
dyspnoea
Neural drive= Increased RR = decreased expiratory timeNeural drive= Increased RR = decreased expiratory time
Expiratory flow limitation = need for increased expiratory timeExpiratory flow limitation = need for increased expiratory time
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
+4 +4
0
+2
+2 +4 +4
0
forced expiration( obstructive airway disease)
+5
+4
+3
+6
+4+4
+5
+4
+6
+4+4
Pursed lip breathingPEEP
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
MANAGEMENT GOALGOAL
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
CORRECTION OF GAS EXCHANGEREDUCTION OF WOB
CORRECTION OFLUNG MECHANICS
TREATMENT OF BASELINE DISEASE
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Prevention of DHI
CORRECTION OF LUNG MECHANICS
Reduce airway resistance
PPV PEEP
•Easy Inspiratory flow•Prevention of DAC
Reduce airway resistanceTreatment of disease •Prevention of DAC
Neuro muscular recouplingsedation,anti anxiety
PPV Adequate expiratory time
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Positive Pressure Ventilation
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
PEEPFor easy inspiration
o +7
+10 +10
-11 -4
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
-7 -7
0
Beginning of inspiration
TPP = PA – Ppl
Ppl = -7
+5 = PA – (-7)
+10
-7-7
+5 = PA – (-7)
PA = +5 – 7 = -2
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
+4 +4
PEEP For easy expiration
+5
+4
+3
+6
+4+4
PEEP
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
Setting total cycle timeSetting total cycle timeFlow riseFlow risecyclingcyclingcyclingcycling
Calculation of expiratory timeCalculation of expiratory timeCalculation of TCTCalculation of TCT
Ubaidur Rahaman, Senior Resident, CCM, SGPGIMS, Lucknow, India
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