Download Respiratory Support For Children with Heart Disease

Respiratory Support For
Children with Heart Disease
Reference: Congenital Heart Disease in Infants and Children,
Second Edition, 2006, publisher MOSBY, Elselvier
Factors that INCREASE PVR
Increase PaCO2
Decrease pH
Decrease ventilatory rate
Decrease tidal volume
Add CO2 or dead space
Increase PEEP (overdistention)
Atelectasis
Pain
Agitation
Dopamine
Epinephrine
Factors that INCREASE Systemic
Ventricle Afterload
Increase SVR
High-dose dopamine
Epinephrine
Norepinephrine
Pain
Agitation
Factors the DECREASE PVR
Decrease PaCO2
Increase pH
Factors that DECREASE Systemic
Increase ventilatory rate
Ventricle Afterload
Increase tidal volume
Inspired oxygen
Decrease SVR
Optimize lung volume (neither overdistention or atelectasis Milrinone
Inhaled nitric oxide
Dobutamine (increases HR)
Adequate analgesia
Captopril, enalapril
Adequate sedation
Nitroprusside (unpredictable effect)
Muscle relaxation
Adequate analgesia
Milrinone
Adequate sedation
Prostaglandin E1 (for ductal dependent PBF)
Mechanical Ventilation
• Life saving tool
• Complication risk:
• Ventilator induced lung injury
• Nosocomial pneumonia
• Increases sedation requirements
• ETT airway injury
• Cardiovascular instability
• Bottom line: Discontinue as soon as possible
Goals of Respiratory Support
• Optimize oxygen delivery by:
• Improved blood oxygen content
(arterial sat%)
• Decreased oxygen demand (▼work
of breathing)
• Improve Carbon Dioxide elimination
Start Simple!!!
Initial Ventilator Settings
FiO2 = 0.6-1.0
Vt= 6-8 mL/kg
RR=15-35 breaths/min (age based)
Ti=0.3-1.0 seconds (neonate/child, considering RR)
Ti=0.75-1.5 seconds (Adult, considering RR)
Peep=2-4 cm H20
Mode=SIMV/PS
SaO2 < 85%
Go to inadequate O2
Delivery algorithm
Adequate O2 delivery
Adequate CO2 Elimination
Wean FiO2 to < 0.60 rapidly
For SaO2 > 90-92%
Wean RR for PaCO2 < 50 mmHG
Cardiorespiratory status is stabilized
Clinical/Radiograph/PFTs improving
FiO2 ≤ 0.50, RR < 25, PEEP ≤ 6 cm H2O
PaCO2 > 50 mmHg
Go to inadequate CO2
elimination algorithm
Decreased SaO2 Differential Diagnosis
Right-to-Left Intracardiac Shunt
Diagnosis: No significant response
to FiO2 of 1.0
Medical treatment directed at:
Improving Oxygen Delivery
Increase hemoglobin
Increase cardiac output
Improving Pulmonary Blood Flow
Decrease pulmonary vascular resistance
Improve right ventricular function
Surgical treatment as indicated
Intrapulmonary Shunt
Diagnosis = P(A-a)O2 gradient
Alveolar Hypoventiliation
Diagnosis = No P(A-a)O2 gradient
 FiO2
Optimize PEEP
Assess respiratory mechanics
Increase FiO2
Increase VT
if no improvement
Assess total volume delivery (6 ml/kg)
Decelerating flow ventilation
(i.e. Pressure control ventilation of pressure
regulated volume control)
if no improvement
Reevaluate
Complete PFTs
Consider HFOV
if no improvement
Consider ECMO
Increased PaCO2 Differential Diagnosis
Small Airway Obstruction
Small Airway Obstructions/Alveolar Collapse
Bronchospasm
Inadequate Effective Alveolar Ventilation
Increased Te
Decreased RR, Increased VT
Decreased Ti
Bronchodilator therapy/Steroids
Support spontaneous ventilation
with pressure support up to 35 cm H2O
and increased PEEP to decrease
expiratory work of breathing and
support active exhalation
Sedation/paralysis
Increase VT to 10 mL/kg
If no improvement
Increase RR (Monitor for “gas
trapping” and intrinsic PEEP
Consider decelerating flow ventilation
(i.e., PCV, PRVC)
If no improvement
Increase sedation, add paralysis
if no improvement
Consider high-frequency ventilation
Large Airway Obstruction
Assess for ETT obstruction
Suction/Physiotherapy
Consider changing endotracheal tube
Bronchoscopy
Weaning and Extubation
Readiness
Clinical Criteria for Extubation
Readiness
• Ventilator settings “sufficiently” weaned
• Patient awake
• Intact airway reflexes
• Hemodynamically stable
• Secretions manageable
Summary of Current
Pediatric/Adult Weaning Studies
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Gradual weaning may not be necessary
No reliable extubation readiness test
T piece and PS can be equally effective ERT
Lower vent rate weans are inferior ERT
Weaning protocols = faster weaning in adults
• Corticosteroids: Not as effective as we think?
Risks for Extubation Failure
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Young age (<24 months)
Dysgenetic or syndromic condition
Chronic respiratory disorder
Chronic neurologic condition
Need to replace ETT at admission for any
reason
• Upper airway obstruction: 37% of failed
extubations
Extubation Failure
• Defined as re-intubation within 24-48 hours of
extubation
• Pediatric failures: 4-8%
• Emergent reintubation risks:
• Adult and Pediatric studies
• Associated with high mortality rate
• Increased potential for morbidity
• Pediatric extubation failure=5 fold increase
in the risk of death
Upper Airway Obstruction (UAO)
• UAO is associated with failed extubation
• Cuffed vs Uncuffed debate
• Leak test: air leak is heard around ETT at low
pressure (<20-25 cm H2O)
• Poorly reproducible
• High utilization rate despite inadequate
evidence
• Serial measurements superior to single
Non-invasive Ventilation
NIV Advantages
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Positive pressure ventilation without the ETT
CPAP: Continuous positive airway pressure
Easy to utilize
Multiple applications: Only 4 tested with RCT
• COPD exacerbations
• Acute cardiogenic pulmonary edema
• Facilitating extubation in COPD patients
• Immunocompromised patients
NIV: When to use it?
• Clinical State:
• Sick but not moribound
• Able to protect airway
• Conscious and cooperative
• Haemodynamically stable
• No excessive respiratory secretions
• Feeding issues?
Contra-indications to NIV
• Facial burns/trauma
• Recent facial or upper airway surgery
• Fixed upper airway obstruction
• Vomiting
• Undrained pneumothorax
Setting Up NIV
• Mode: CPAP versus BIPAP
• EPAP: 4-5 cm H20
• IPAP: 12-15 cm H20 (increase to 20
cm H20)
• Triggers: Maximum sensitivity
• Back up rate: 15 breaths/min
• Back up I:E ratio 1:3
Initiating NIV
• Prepare for Plan B if NIV fails
• Explain NIV to patient
• Select mask and hold in place for several
minutes prior to starting ventilator
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Set up ventilator
Start NIV and hold mask on patient face
Place straps/headgear if mask tolerated
Reassess after a few minutes
Adjust as necessary
Recheck +/- blood gases in 1-2 hours
Clinical Assessment for
Response: NIV
• Chest wall movement
• Coordination of respiratory effort with the
ventilator
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Accessory muscle recruitment
Heart rate
Respiratory rate
Patient comfort
Mental state
Troubleshooting NIV
• Is the treatment of underlying condition optimal?
• Have complications developed?
• Pneumothorax, aspiration pneumonia, crepitus
• PaCO2 still elevated?
• Too much oxygen?
• System leakage? Mask fit, chin strap, full face, circuit leaks
• Is rebreathing occurring? Patency of expiratory valve,
increase EPAP
• Is patient synchronizing with ventilator?
• Is ventilation adequate?
• PaCO2 improves but PaO2 remains low
• Increase FIO2
• Consider increasing EPAP (with bilevel)
Discussion