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Cardiorespiratory Interactions
1. Cardiorespiratory
Interactions:
The Heart - Lung
Connection
Jon N. Meliones, MD, MS, FCCM
Professor of Pediatrics Duke University
Medical Director PCICU
2. Optimizing CRI
• Cardiorespiratory Economics
O2: supply vs. demand
CRI: The Heart
CRI: The Lung
Conventional Ventilation
Non-Conventional Ventilation
Clinical Applications
3. Cardiorespiratory
Economics
• O2 Demand:
O2 consumption = C. O. x (CaO2 - CvO2)
O2 Consumption = amount of oxygen used
for aerobic metabolism
•Failure to meet the demands
results in anaerobic metabolism
5. Cardiorespiratory Interactions
A Definition
Effects of intrathoracic pressure,
lung volume, and gas exchange
on:
Cardiovascular events such as venous
return, ventricular performance, and
arterial outflow.
9. Systemic Venous Return
(RV Preload)
PSV RAP = mean systemic venous pressure
PPV increases
right atrial pressure
Right
spontaneous
Atrial
breathing
Pressure
0
0 Max
Systemic Venous Return
10. Effects of PPV on Right Ventricle
es in intrathoracic pressure C.O.
ing RV preload
ing RV afterload by ing PVR
Best strategy for the failing RV is
to limit intrathoracic pressure
11. Effects of PPV on LV Filling
Thoracic Pump Augmentation
Lung Lung
Positive
LA
Pressure
Ventilation
LV
AO
12. Effects of PPV on LV Afterload
100
100
AO AO
LVTM=130 LVTM=70
70
Thorax
130
LV
LV
+30
-30
Spontaneous PPV
13. Effects of PPV on Left Ventricle
es in intrathoracic pressure C.O.:
ing LV preload when low
ing LV afterload
preload when excessive (RV) effects
Best strategy for the failing LV is to utilize
intrathoracic pressure to optimize preload &
afterload
14. Optimizing CRI
Cardiorespiratory Economics
CRI: The Heart
CRI: The Lung
The pulmonary vasculature
Conventional Ventilation
Non-conventional Ventilation
Clinical Applications
15. Effect of Lung Volume on PVR
Overexpansion
Atelectasis
PVR
Total PVR
Small Vessels
Large Vessels
FRC
Lung Volume
16. LA
RA
QuickTime™ and a
Microsoft Video 1 decompressor
are needed to see this picture.
LV
RV
25. Intrinsic PEEP
Beginning Premature initiation
of of Inspiration
Inspiration
End
of
Inspiration
Retained Gas
Results in PEEP
Termination
Beginning
Premature
of
of
Termination of
Exhalation
Exhalation
Exhalation
26. Intrinsic PEEP
• Expiratory gas flow continues at the
end of the time allotted for
exhalation.
• PEEPi may lead to excessive MAP.
– Pulmonary effects:
• Barotrauma
– Cardiac effects:
• Impedance of venous return
• Decreased cardiac output
29. PIP
at
HFOV
Machine
PIP
at MAP
Alveolus at
Alveolus
Delta P
at
Machine
Delta P
at
MAP
Alveolus
at PEEP
Machine at
Alveolus
PEEP
at
Machine
30. HFOV
HFOV decreases cardiac output??
Traverse et al Pediatr Res. 1988.
Traverse et al. Chest. 1989.
Laubscher et al. Arch Dis Child. 1996.
Theme: Cardiac output decreases
with “significantly” ed MAP
But, studies did not control for
preload.
32. HFOV and CRI: Summary
Cardiac output is maintained during HFOV
In a given pt, C.O may be ed if:
MAP is “significantly” ed.
Consider volume loading
Consider inotropes
Bottom line: Oxygen delivery
If C.O. can be maintained & oxygenation is ed
Oxygen delivery will
33. High-frequency Jet Ventilation
Intermittent pulse delivery of gas
Frequency: 180 - 900
Passive exhalation
Special ETT adaptor required
Weight/size limitation (Bunnell Jet)
35. RA LA
QuickTime™ and a
RV Cinepak decompressor
are needed to see this picture.
LV
36. Effects of HFJV on CRI
* p < 0.01 vs HFJV
*
*
10 Pre
HFJV
9.4
9.4
8 Post
6
* *
4 4.6 *
*
3.8 3.7
2.9
2 2.3 2.4
1.6
0
Paw PVR C.I.
37. Inhaled NO
PAO2, cGMP Oxygen
A 2,
Ca++, PVR NO
Epithelial Cells
Interstitium
Muscle
Endothelial Cells cGMP
NO
Injured
CA++
EDRF
Relaxation
NO
Capillary
Hgb
Met Hgb
38. NNitric Oxide In CHD
OI Miller, SF Tang, A Keech, NB Pigott, E Beller and DS
Celermajer: Lancet 2000
• 126 Pts, randomized
• Less Pulm HTN crisis, Less Vent Days.
• No difference in mortality
• Patients with passive flow, worse response,
better in “small vessels”
• Use lowest dose, wean daily.
• Use sildenafil
44. Single Ventricle
Pulm Veins
Vena Cava
LA
RA 65 99
LV
80
RV
80
PA AO
PDA
45. Causes of Systemic Desaturations
• Sao2 is dependent on
– 1. SmvO2
– 2. SpvO2
– 3. Volume of Pulmonary venous vs
systemic venous return
• Decreased oxygen delivery to the
tissues
– Lowering of SmvO2 i.e QS
• Alveolar arterial gradient
– Lowering SpvO2
• Alterations in QP/QS
46. Norwood With BT Shunt
Procedure:
3 1. Create unobstructed
SBF
outlfow to aorta = create
PBF neoaorta
2. Unobstructed mixing in
atrium = atrial
septectomy
21 3. Stable PBF = BT shunt
vs RV-PA shunt (Sano)
Benefits:
– Not ductal dependent
– RV is systemic pump
– Coronary perfusion stable
Problems:
– Gore-Tex doesn’t grow
– Shunts clot
– Still cyanotic (80%)
47. Norwood With Sano
Procedure:
1. Create unobstructed
SBF outlfow to aorta = create
3 PBF neoaorta
2. Unobstructed mixing in
atrium = atrial
septectomy
3. Stable PBF = RV-PA
21 shunt (Sano)
Benefits:
– Not ductal dependent
– RV is systemic pump and
SANO may provided better
function
– Coronary perfusion stable
Problems:
– Shunts clot
– Still cyanotic (and lower
SaO2 vs BT shunt)
– RV is still volume
48. Single Ventricle Management Key Points
Pulmonary Blood BT shunt Sano
flow
Flow occurs during Systole & Systole
diastole
SaO2 Higher lower
Less diastolic run off No Yes
and possible better
ventricular function
49. Qp / Qs Ratio =
Ratio of Oxygen Extraction of the
Systemic vs Pulmonary Bed
Qp SaO2 – SmvO2
SpvO2 – SpaO2
Qs
a= arterial
mv= mixed venous
pv= pulmonary vein
pa= pulmonary artery
50. Qp:Qs Ratio
Since Aortic and Pulmonary Blood
Flow both come from the Aorta:
Aortic Sat. = Pulmonary Sat.
SaO2 – SmvO2
SpvO2 – SaO2
In a SV patient:
a= arterial
mv= mixed venous
pv= pulmonary vein
51. Qp:Qs Ratio
If one assumes Pulmonary
Venous Sat. = 95% then:
Qp:Qs =
SaO2 – SmvO2
95 – SaO2
In a SV patient:
Assume:
SpaO2 = SaO2
SPVO2 = 95
Measure:
SaO2 and SmvO2
55. Qp:Qs Ratio = 1/1
Balanced Pulmonary Blood
Flow
35 1
60 – 25
= = 1
35
95 – 60
In a SV patient:
Balanced shunt flow: Low CO
Increase CO: Epin., Milrinone
56. Effects of Inspired Gas on
Pre-op Single Ventricle
6
Difference in DO2
5
4
3
2
1
0
Hypoxia Hypercapnea
Pre Post
57. What are the Key Issues for the management of
a post Norwood patient?
• SaO2 target is between 70-80% so keep Hgb >15
• SmvO2 target = >55 but usually common atrial line so
use cerebral O2 (are they any good? Yes for trends)
• Lactates are followed on all pts. If < 2.5 good. If
increases > 1/hr bad sign. Keep they alive.
• Chest is usually open… risk for tamponade!
• The answer is always!!! Increase QT!
• Steroids although no data
58. Post Op Management
• Balance Qp/QS (careful! Just
increase the PaCO2)
– Low FI02 with B-T shunt
– FIO2 = 0.4 with sano
– Consider adding CO2
– NEVER use hypoxia
– NEVER bag with FIO2 = 1.0
59. Optimizing CRI
• Cardiorespiratory Economics
O2: supply vs. demand
CRI: The Heart
CRI: The Lung
Conventional Ventilation
Non-Conventional Ventilation
Clinical Applications