neonatal non-invasive respiratory support: overview and …€¦ · ppt file · web view ·...
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Neonatal Non-Invasive Respiratory Support:
Overview and ChallengesJeffrey S. Gerdes, MD, MBA
Associate Chair, Department of PediatricsChildren’s Hospital of Philadelphia
Associate Professor, Perelman School of Medicine
Emidio M. Sivieri, MSEResearch Bioengineer, CHOP Newborn Care at Pennsylvania Hospital
Why Non-Invasive Support?• Airway distending pressure to maintain FRC is the
cornerstone upon which all other support modalities are built
• Less Chronic Lung Disease• Fewer airway complications• Fewer Infections• Reduced inflammation• Less stress for babies, families, and staff• Lower cost
Increasing HFNC UseAll Patients during NICU Stay
Courtesy of Dr. Reese Clark, Pediatrix
All Patients during NICU Stay
NIPPVSiPapNAVA
NCPAPNIV using
RAM Cannula
HFONC
??????????????????
HFNC
Questionof the day
• Mechanisms of Action• Physiologic Rationale• Challenges for Clinical
Research
Nasal CPAP: Physiologic Rationale• Distending pressure recruits lung volume• Increases and stabilizes FRC• Splints upper airways and compliant chest wall• Improves lung Compliance• Reduces airway Resistance• Decreases Work of Breathing• Improves gas exchange• Reduces apnea
NCPAP: Mechanisms of Delivery• Constant flow: flow
opposition (conventional vent)
• Constant flow: liquid seal (bubble)
• Variable flow: “fluidic flip” (Infant Flow)
• Patient expiratory flow opposes system flow and an expiratory resistor valve
• Expiratory limb submerged in liquid, with oscillatory nature
• Inspiratory and expiratory flow compensation via fluidics engineering
All NCPAP devices are not created equal
• Variable flow reduces WOB compared to conventional vent CPAP (Lipsten et al, J Perinatol 2005)
• Variable flow may compensate better for mouth or seal leakage• Bubble oscillations may improve lung recruitment
(Pillow et al, Am J Crit Care Med 2007)
• Bubble CPAP pressure delivery is flow dependent and not reliably delivered relative to liquid depth (Kahn et al, Pediatr Res 2007)
• Bubble CPAP pressure delivery varies more than variable flow CPAP (Kahn et al, Pediatr 2008)
• Nasal interfaces vary in resistance to flow (DePaoli et al, Arch Dis Child Fetal Neonatal Ed 2002)
• Variable safety regarding alarms and expiratory limb obstruction risk
Examples:
at 6 L/min
Pressure-drop across prongs - by manufacturer
RAM (micro-preemie )
RAM (preemie)
RAM (Newborn)
Modified from: De Paoli, Morley, Davis et al. Arch Dis Child Neonatal Ed 2002
(All at 6 L/min Flow)
0 2 4 6 8 21Pressure drop (cmH2O)
Effect of mouth leak
3 4 5 6 7 8
8
7
6
5
4
3
2
1
0
Set CPAP (cm H2O)
Pha
ryng
eal p
ress
ure
(cm
H2O
)
De Paoli, et al. Arch Dis Child Neonatal Ed 2005
4 6 8Bubble Bias Flow (L/min)
Mea
n Pr
essu
re (±
SD)
(cm
H2O
)
210 12
Set CPAP
Bubble CPAP vs. CPAP with Mech. Ventilator
Kahn, Habib, Courtney, Pediatrics 2008
Bubble CPAP pressure is flow dependent
Bubble CPAPVentilator
No Leak
12
10
8
6
4
8
4
Clinical Correlations of different CPAP Drivers and Interfaces
• Clinical studies often do not offer clear actionable results
• Do mechanistic differences matter, or have they not been discoverable with current studies?
• Babies have widely variable pathophysiology and severity of illness
• Do the large pragmatic trials of NIRS strategies deliver specific answers for relative efficacy when the “gold standard” of CPAP is delivered with widely divergent modalities?
NIPPV or SNIPPV: Physiologic Rationale
• Benefits of NCPAP + additional tidal ventilation and/or lung recruitment from higher MAP
• May reduce WOB relative to CPAP (Aghai et al, Pediatr Pulmonol 2006; Chang et al, Ped Res 2011)
• Airway pressures actually delivered vary considerably from settings (Owen et al, Arch Dis Child Fetal Neonat Ed. 2010 )
• Is variable pressure delivery favorable to lung function?• Is apnea Improved through cyclic receptor stimulation?• Synchronization may improve efficacy• Unclear if NIPPV or bi-level CPAP is more efficacious
(Roberts et al, Pediatrics 2013)
• Are these modalities “Super CPAP”?
Heated and Humidified High Flow Nasal Cannula
HFNC: Mechanisms of Action
Gas Conditioning Effects
Flow Effects
Pressure Effects
HFNC: Mechanisms of Action
Gas Conditioning Effects
• Reduces patient’s metabolic workload needed for Heating and Humidifying
(Waugh et al, Granger, RespCare 2004)
• Improves mechanics-H&H Increases Compliance and Conductance
(Greenspan et al, J Peds 1991)
HFNC: Mechanisms of ActionFlow Effects
• Improves lung mechanics- Reduced inspiratory resistance => Reduced resistive Work of
Breathing (Saslow et al, J Perinatol 2006)- Expiration: possible “Coanda” effect (Dysart et al, Resp Med 2009)
• Washout of Nasopharyngeal dead space => Improved gas exchange (Frizzola et al, Pediatr Pulm 2011)
As flow increases, CO2 elimination > increase in MAP Analogous to Trans Tracheal Catheter TGI
Washout of anatomical dead space
• Continuous flow washes out the upper airways and leads to improved oxygenation
• Reservoir of fresh gas in upper airway
• Avoids rebreathing of high-CO2 gas in dead space
Schibler et al, Int Care Med 2011
Courtesy of Walsh et al, Resp Care 2009
Nasal cannula
Proposed flushing of dead space at higher flows
Washout of nasopharyngeal cavityWashout
flow exitingthe mouth
HFNC: Mechanisms of ActionPressure Effects
• HFNC has been shown to provide positive distending pressure- Highly dependent on prong-to-nares diameter ratio and
degree of mouth closure (Locke et al, Pediatrics 1993; Sivieri et al, Pediatr Pulm 2013)
ProngsO.D.
Nares I.D.
HFNC set flow (L/min)0 1 2 3 4 5 6
Mean A
irway Pressure (cm
H2O)
0
5
10
15
20
25
F&P Neonatal Cannula (3.0mm prongs)F&P Infant Cannula (3.7mm prongs)
prongsO.D.
naresI.D.
3.0 5.0 3.0 4.5
3.7 5.03.7 4.5
3.0 3.5
HFNC set flow (L/min)0 1 2 3 4 5 6
0.0
0.5
1.0
1.5
2.0
2.5
74%
68%55%
44%36%
Intra-cannula
pressure (74% occl.)
Pressure Limiting Safety Valve opens
PercentOcclusion
74%68%55%44%36%
PercentOcclusion
100%86%
Mouth Fully Closed Mouth Fully Open
HFNC Pressure Delivery:Effect of flow rate, % nares occlusion,
and mouth leak
Sivieri, Gerdes, Abbasi. Pediatr. Pulm. 2013
HFNC delivered pressurePh
aryn
geal
Pre
ssur
e (c
mH
2O)
Flow 2 Lpm Flow 4 LpmFlow 6 Lpm
1 minute
Wilkinson et al, J Perinatol 2008
Causes of variability of delivery of HFNC
• % nasal occlusion by catheter • Characteristics of catheter design • Characteristics of gas conditioning with heat and
humidity• Mouth leak• Variability in disease state of the patient
RAM CannulaTM (Neotech Products)
• Soft nasal prong interface, relatively large ID• FDA approved as a Class I medical device, as a nasal
cannula for delivering oxygen: CPAP interfaces are Class 2 Medical Devices
• 3 sizes: micro-preemie (ID 2.0 ,OD 2.7), preemie (ID 2.0, OD 2.9), newborn (ID 2.5, OD 3.1 )
• “Expiratory limb” much smaller diameter than CPAP interfaces
• Recommended % nasal occlusion: 60-80%• Connector attaches to standard ventilator tubing• Has been used to deliver CPAP, NIMV, HFONV
RAM CannulaTM (Neotech Products)
RAM CannulaTM (Neotech Products)
• Soft nasal prong interface, relatively large ID• FDA approved as a Class I medical device, as a nasal
cannula for delivering oxygen: CPAP interfaces are Class 2 Medical Devices
• 3 sizes: micro-preemie (ID 2.0 ,OD 2.7), preemie (ID 2.0, OD 2.9), newborn (ID 2.5, OD 3.1 )
• “Expiratory limb” much smaller diameter than CPAP interfaces
• Recommended % nasal occlusion: 60-80%• Connector attaches to standard ventilator tubing• Has been used to deliver CPAP, NIMV, HFONV
`
Nasal CPAP setting (cmH2O)4 5 6 7 8
Mean A
irway Pressure (cm
H2O)
0
1
2
3
4
5
6
7
8
94.5
3.0
3.5
4.0
4.5
5.0
Nasal CPAP setting (cmH2O)4 5 6 7 8
0
1
2
3
4
5
6
7
8
9100%100%
78%
60%
48%
38%
Percent OcclusionMouth Fully Closed Mouth Fully Open
RAM Cannula Pressure Delivery:Bench Test
Gerdes, Sivieri, Abbasi, EAPS Congress 2014
Dräger BabyFlow M prongs 4.5mm O.D.RAM Preemie Cannula 3.1 mmO.D. prongs
Nares I.D.
RAM Cannula used for “NCPAP”• In bench tests, RAM cannula interface delivers 60% less
than the MAP set on the ventilator, even with mouth closed
• With mouth open, delivered MAP is further reduced
• By design, RAM cannula is neither NCPAP nor HFNC
• Using 60-80% nares occlusion does not provide sufficient seal to deliver CPAP.
• Due caution should be applied if using RAM cannula interface to provide CPAP, pending further studies and classification as a Class II Medical Device
Nasal High Frequency Ventilation
Initial pCO2 Final pCO2
2 hours NHFV
pCO
2 (m
m H
g)75
70
65
60
55
50
45
40
35
30
Colaizy et al, Acta Paediatr. 200
Infant Star, Single Nasopharyngeal tubeFrequency 10HzAmplitude 50 torr
n=14 InfantsGA 27 (25-30) wksBW 1.6 (1.1-2.9) kg
p = 0.011
NIPPVSiPapNAVA
NCPAPNIV using
RAM Cannula
HFONC
• Mechanisms of Action• Physiologic Rationale• Challenges for Clinical
Research
Does it matter which NIRS strategy is used in a given patient or NICU?
HFNC
Questionof the day
Pulmonary Factors to Consider When Evaluating NIRS Systems
Physiologic mechanisms imply that:
- NCPAP/NIPPV might be better for lung recruitment- HFNC might be better for CO2 retention- NIPPV might be better for apnea
Are we reasonably able to study these differences, And are these differences clinically important?
BUT
Extra-pulmonary Factors to Consider When Evaluating NIRS Systems
• Minimizing nasal septal injury
• Ease of nursing and respiratory therapy care
• Comfort for baby and family
• Noise pollution
• Promotion of infant development
• Cost –interface and disposables, amortized cost of the driver, RRT and RN time, and possible impacts on length of stay or severity of illness
NIRS: Summary and Challenges for this conference
• NCPAP, NIPPV, and HFNC all have physiologic rationales and feasible mechanisms of action
• All provide varying degrees of respiratory support which improve physiologic parameters and gas exchange in neonates
• Little is known about which devices may be better for different patho-physiologies or different severities of illness
• Do the clinical trials have sufficient numbers or stratification of diagnoses and severity of illness to differentiate the utility of these modalities? OR,
• Are we left with the current state in which clinicians apply well-studied, safe NIRS techniques according to unit or provider preference, matching the device to the baby’s needs, and response to therapy?
• Are “more randomized trials” the answer, or should we steer towards other research methodologies?
NIRS: Summary and Challenges for this conference