Presentation on theme: "Neonatal Non-Invasive Respiratory Support: Overview and Challenges"— Presentation transcript:
1 Neonatal Non-Invasive Respiratory Support: Overview and Challenges Jeffrey S. Gerdes, MD, MBAAssociate Chair, Department of PediatricsChildren’s Hospital of PhiladelphiaAssociate Professor, Perelman School of MedicineEmidio M. Sivieri, MSEResearch Bioengineer, CHOP Newborn Care at Pennsylvania Hospital
3 Why Non-Invasive Support? Airway distending pressure to maintain FRC is the cornerstone upon which all other support modalities are builtLess Chronic Lung DiseaseFewer airway complicationsFewer InfectionsReduced inflammationLess stress for babies, families, and staffLower costArguably, CPAP for RDS (Gregory) was the single most important support strategy for RDS. Perhaps after surfactant, which is a drug not a deviceBeyond CPAP, even fancier modes of ventilation such as HFOV vs. CMV have not shown differences among them, and all have MAP is cornerstone
4 All Patients during NICU Stay All Patients during NICU Stay Increasing HFNC UseAll Patients during NICU StayAll Patients during NICU StayCourtesy of Dr. Reese Clark, Pediatrix
5 HFNC NCPAP NIV using RAM Cannula NIPPV HFONC SiPapNAVAHFONCMechanisms of ActionPhysiologic RationaleChallenges for Clinical ResearchQuestionof the day??????????????????
6 Nasal CPAP: Physiologic Rationale Distending pressure recruits lung volumeIncreases and stabilizes FRCSplints upper airways and compliant chest wallImproves lung ComplianceReduces airway ResistanceDecreases Work of BreathingImproves gas exchangeReduces apneaChoosing a CPAP device should address all of these factors, and results may vary depending on lung pathology vs. apnea as major clinical problemReduces apnea as combo of splinting airway and stimulating receptors (Head’s paradoxical reflex)
7 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 valveExpiratory limb submerged in liquid, with oscillatory natureInspiratory and expiratory flow compensation via fluidics engineering
8 All NCPAP devices are not created equal Examples:Variable flow reduces WOB compared to conventional vent CPAP (Lipsten et al, J Perinatol 2005)Variable flow may compensate better for mouth or seal leakageBubble 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
9 Pressure-drop across prongs - by manufacturer at 6 L/minRAM (micro-preemie )RAM (preemie)RAM (Newborn)(All at 6 L/min Flow)246821Pressure drop (cmH2O)Modified from: De Paoli, Morley, Davis et al. Arch Dis Child Neonatal Ed 2002
10 Effect of mouth leak Pharyngeal pressure Set CPAP (cm H2O) 8 7 6 5 4 3 1Pharyngeal pressure(cm H2O)345678Set CPAP (cm H2O)De Paoli, et al. Arch Dis Child Neonatal Ed 2005
11 Bubble CPAP vs. CPAP with Mech. Ventilator Bubble CPAP pressure is flow dependentBubble CPAPVentilator121088Mean Pressure (±SD)(cm H2O)Set CPAP6442No Leak4681012Bubble Bias Flow (L/min)Kahn, Habib, Courtney, Pediatrics 2008
12 Clinical Correlations of different CPAP Drivers and Interfaces Clinical studies often do not offer clear actionable resultsDo mechanistic differences matter, or have they not been discoverable with current studies?Babies have widely variable pathophysiology and severity of illnessDo 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?
13 NIPPV or SNIPPV: Physiologic Rationale Benefits of NCPAP + additional tidal ventilation and/or lung recruitment from higher MAPMay 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 )Is variable pressure delivery favorable to lung function?Is apnea Improved through cyclic receptor stimulation?Synchronization may improve efficacyUnclear if NIPPV or bi-level CPAP is more efficacious (Roberts et al, Pediatrics 2013)Are these modalities “Super CPAP”?
15 HFNC: Mechanisms of Action Gas Conditioning EffectsFlow EffectsPressure Effects
16 HFNC: Mechanisms of Action Gas Conditioning EffectsReduces 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)
17 HFNC: Mechanisms of Action Flow EffectsImproves lung mechanicsReduced 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
18 Washout of anatomical dead space Continuous flow washes out the upper airways and leads to improved oxygenationReservoir of fresh gas in upper airwayAvoids rebreathing of high- CO2 gas in dead spaceProposed flushing ofdead space at higher flowsSchibler et al, Int Care Med 2011Washout of nasopharyngeal cavityWashoutflow exitingthe mouthNasal cannulaCourtesy of Walsh et al, Resp Care 2009
19 HFNC: Mechanisms of Action Pressure EffectsHFNC has been shown to provide positive distending pressureHighly dependent on prong-to-nares diameter ratio and degree of mouth closure (Locke et al, Pediatrics 1993; Sivieri et al, Pediatr Pulm 2013)
22 Causes of variability of delivery of HFNC % nasal occlusion by catheterCharacteristics of catheter designCharacteristics of gas conditioning with heat and humidityMouth leakVariability in disease state of the patient
23 RAM CannulaTM (Neotech Products) Soft nasal prong interface, relatively large IDFDA approved as a Class I medical device, as a nasal cannula for delivering oxygen: CPAP interfaces are Class 2 Medical Devices3 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 interfacesRecommended % nasal occlusion: 60-80%Connector attaches to standard ventilator tubingHas been used to deliver CPAP, NIMV, HFONV
25 RAM CannulaTM (Neotech Products) Soft nasal prong interface, relatively large IDFDA approved as a Class I medical device, as a nasal cannula for delivering oxygen: CPAP interfaces are Class 2 Medical Devices3 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 interfacesRecommended % nasal occlusion: 60-80%Connector attaches to standard ventilator tubingHas been used to deliver CPAP, NIMV, HFONV
26 RAM Cannula Pressure Delivery: Bench Test `Mouth Fully ClosedPercent OcclusionMouth Fully OpenDräger BabyFlow M prongs 4.5mm O.D.RAM Preemie Cannula 3.1 mmO.D. prongsNaresI.D.100%100%78%60%48%38%Gerdes, Sivieri, Abbasi, EAPS Congress 2014
27 RAM Cannula used for “NCPAP” In bench tests, RAM cannula interface delivers 60% less than the MAP set on the ventilator, even with mouth closedWith mouth open, delivered MAP is further reducedBy design, RAM cannula is neither NCPAP nor HFNCUsing 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
29 Does it matter which NIRS strategy is used in a given patient or NICU? HFNCNCPAPNIV using RAM CannulaNIPPVSiPapNAVAHFONCMechanisms of ActionPhysiologic RationaleChallenges for Clinical ResearchQuestionof the dayDoes it matter which NIRS strategy is used in a given patient or NICU?
30 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 apneaBUTAre we reasonably able to study these differences,And are these differences clinically important?
31 Extra-pulmonary Factors to Consider When Evaluating NIRS Systems Minimizing nasal septal injuryEase of nursing and respiratory therapy careComfort for baby and familyNoise pollutionPromotion of infant developmentCost –interface and disposables, amortized cost of the driver, RRT and RN time, and possible impacts on length of stay or severity of illness
32 NIRS: Summary and Challenges for this conference NCPAP, NIPPV, and HFNC all have physiologic rationales and feasible mechanisms of actionAll provide varying degrees of respiratory support which improve physiologic parameters and gas exchange in neonatesLittle is known about which devices may be better for different patho-physiologies or different severities of illnessDo the clinical trials have sufficient numbers or stratification of diagnoses and severity of illness to differentiate the utility of these modalities? OR,
33 NIRS: Summary and Challenges for this conference 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?