Download Single Ventricle Palliation: Stage One Reconstruction

Single Ventricle Palliation:
Stage One Reconstruction
Louise Callow, CPNP, MSN
Pediatric Cardiac Surgery
University of Michigan Congenital
Heart Center
I have no disclosures
What We Know, Why We Care,
How We Learn
• What:
– 1 in 5000 live births
– Goals S1P consistent
• Why:
– Resource utilization
– Morbidity significant, mortality high
– Belief that MBTS and associated low
DBP created tenuous hemodynamics
• How:
– Single Ventricle Reconstruction Trial
(SVR Trial)
– The Tale of Two Shunts
www.wikipedia.org
Rosenthal D. Single Ventricle Reconstruction Trial. A work in Progress. Circulation, 2014; 129:200-2001.
SVR Trial: Searching for Answers
• NHLBI in association with PHN
• 15 clinical centers from May 2005 to
July 2008
• 549 neonates randomized to RVPAS
(N=274) or MBTS (275)
• Primary outcome transplant free
survival at 12 months
SVR Trial Outcomes
• Overall:
– 54% mortality S1P
hospitalization
– 33% mortality interstage
• Shunt: The winner?
– RVPAS lower freedom from
death or OHT at 12 months
(74% vs 64%)
– Really??????
Ohye RG et al. N Engl J Med 2010;362:1980-1992.
The Tale of Two Shunts
– No difference clinical sequelae,
cause of death (cardiovascular) or
early mortality
– ESV and EDV lower, EF higher in
RVPAS
– No difference in MAP, although
DBP higher with RVPAS
– MBTS mortality higher early,
RVPAS later
– Effects of shunt choice neutralized
by 14 months
Norwood Operation—S1P
• S1P
– Arch reconstruction
– Controlled PBF through shunt
– Nonrestrictive ASD
• Parallel circulation
– Output determined by relative resistance
between circulations
• Decreased ventricular mass
• Cardiac output twice normal at baseline
• Increased oxygen demand
– Surgical trauma
– Myocardial edema/inflammation from CPB
– Post ischemic RV
www.blogspot.com
Goals of Postoperative Care
•
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Balancing the parallel circulation
– PBF for oxygenation
– SBF for aerobic metabolism, avoid volume
load on SV
– SVR/PVR
Matching oxygen delivery, demand and
consumption
– Dependent on optimizing CO
– Maintain end organ function
Remember the shunt
– MBTS: afterload reduction, vasopressors
for DBP, manipulation of ventilation
– RVPAS: maintain RVEF for PBF, inotrope,
volume, HR control
Migliavacca F et al. Modeling of the Norwood circulation: effectsof shunt
size, vascular resistances and heart rate. Am J Physiol Heart Circ Physiol.
2001;280:2076-2080.
DO2 and SaO2
- Increase CO  increase
Qp:Qs and SaO2
- DO2 declines
DO2 and SvO2
- SvO2 /DO2 better, more accurate
predictor DO2/demand balance
- Only value predict mortality
- SvO2 <40% reflects critical
decrease in DO2
DO2 and AVO2 Difference
- Optimal DO2 for any CO
Qp:Qs < 1
−
 Qp:Qs  lower DO2
and wider AVO2 difference
Qp:Qs and DO2
Assumptions about PvO2
- Errors in PVO2 lead to
serious miscalculation of
Qp:Qs
- Is there a better way?
The Ω Factor
SaO2/SaO2-vO2
- Reflects relative excess DO2
- Ratio of DO2 to consumption
- Linear relationship with CO
- PVO2 irrelevant
- High Ω  high DO2
Oxygen Consumption and DO2
The Patient Issue: Parts of S1P
- Sedate/paralyzed?
- Fretful?
- Seizure?
- Fever/infection?
- NPO or feeding?
Change consumption change slope
of relationship Ω and DO2
Goal Directed Therapy
Remember:
-
Slight increase in SaO2 may create large decrease in DO2
Low SvO2 indicate low DO2
Estimating Qp:Qs leaves potential for errors
Ω linearly related to DO2 and not effected by change in CO and
PV saturation
Balanced circulation maintains DO2 and demand, CO, O2
capacity, O2 consumption and pulmonary oxygenation
Balanced or not if lactate high/trending tissue oxygen deficit
exits
Goal Directed Therapy
Pulmonary Undercirculation
•
•
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•
•
•
SaO2: 60-65%
SvO2: 40%
A-V O2 difference: 20-25
Qp:Qs: <1
Ω: 2-3
Lactate: >4, uptrending
Barnea O et al. Balancing the Circulation: Theoretic Optimization of Pulmonary/Systemic Flow Ratio in Hypoplastic
Left Heart Syndrome. 1994;24:1376-1381.
Goal Directed Therapy
Regain balance: SVR PVR
• Preload for volume loading, contractility, HR and AV
synchrony
• Mild hyperventilation, oxygen, iNO, FRC
• Increase SVR, alpha agents, hypertension
• Decrease demand/consumption
• Maintain O2 carrying capacity
• Treat acidosis, correct electrolytes
• Mechanical issue: too small? tamponade?
• Anticoagulation
• Fluid balance
Goal Directed Therapy
Pulmonary Overcirculation
•
•
•
•
•
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SaO2: 80-85%
SvO2: <40%
A-V O2 difference: >45
Qp:Qs: >2
Ω: 2
Lactate >4, uptrending
Goal Directed Therapy
Regain Balance: SVR PVR
• Preload, contractility, HR
• Mild hypoventilation, hypoxic
gases, FRC, PEEP, PPV
• Decrease SVR
• Match DO2, demand and
consumption
• Mechanical issues: too big?
• Treat acidosis, electrolytes
• Fluid balance
• ECMO
Photiadis J et al. Optimal pulmonary to systemic
blood flow ratio for best hemodynamic status and
outcome early after Norwood operation.
European J Cardio-thorac Surg. 2006;29:551556.
• It’s hard work
• Lots of unknowns
• Need for improvement in all
areas
• Quest for knowledge never
ending
• Nursing SVR trial????????
www.123rf.com