CPAP, SIPAP, HIGH FLOW NASAL CANNULA IN INFANTS: WHICH SHOULD YOU CHOOSE, WHEN, AND WHY? Joanne Nicks, RRT Clinical Education Coordinator Mott Respiratory Care Mott Children’s Hospital, Ann Arbor What is CPAP??? CPAP: Continuous Positive Airway Pressure The concept of CPAP is very simple Inspiratory flow Resistance to flow on exhalation Exhalation valve Water column Flow generator (venturi) Flow itself can create resistance on exhalation Continuous Positive Airway Pressure Ideal CPAP Simple Constant, stable pressure Low work of breathing Humidification Comfortable interface covering a range of patient sizes NEONATAL RESPIRATORY DISTRESS: WHERE IT ALL BEGAN In the 1960’s, mortality from “Hyaline Membrane Disease” was the major cause of death in the United States At President Kennedy’s son, Patrick, died of HMD in 1963; he weighed 2.11 kg this time, treatment modalities such as NCPAP, Mechanical Ventilation, and surfactant replacement therapy did not exist In fact, Neonatal Intensive Care units were not developed until the early 1960’s HISTORY OF INFANT CPAP Gregory, et al in 1971, published “treatment of Idiopathic Respiratory Distress Syndrome with Continuous Positive Airway Pressure” in New England Journal of Medicine Initially used with endotracheal tube, then adapted with mask Use of CPAP Dropped Drastically in the 1970’s and 1980’s Prongs very uncomfortable Damaging effects of CPAP IMPROVEMENTS IN THE “NEWER” CPAP SYSTEMS “Kinder and gentler” approach to CPAP Softer prongs made of silicone Prongs that are shaped to seal without having to be pushed all the way in the nose Small silicone nasal masks CPAP systems that offer lower work of breathing and bi-level pressure delivery Effects of CPAP Increases FRC and reduces atelectasis Increase tidal volume and reduces respiratory rate with RDS Dilates airways and reduces inspiratory resistance Improves V/Q and reduces R>L shunting Reduces upper airway obstruction; stents airways open Stimulates respiratory reflexes, possibly reducing mild apnea Why CPAP? Vol Vol Pressure Normal Ppl Vol Vol Pressure RDS Pressure CPAP Indications for CPAP Spontaneously breathing infants with respiratory distress at birth Atelectasis, pulmonary edema or hemorrhage Apnea of prematurity Early/Post extubation INSURE (Intubate, surfactant, extubation) reduced need for ventilation Tracheomalacia and airway collapse Complications of CPAP Increase work of breathing Respiratory failure Pneumothorax Changes in cerebral blood flow “CPAP” belly Limitations to CPAP Keeping to interface on patient with good seal Pressure instability due to open mouth Chin strap Pacifier Contraindications for CPAP Respiratory Failure with elevated PaCO2 Profound apnea Upper airway abnormalities (cleft palate, choanal atresia) Tracheoesophageal fistula Diaphragmatic hernia Severe cardiovascular instability TYPES OF INFANT CPAP SYSTEMS Conventional CPAP Utilizes conventional ventilator circuit and ventilator to generate CPAP. Continuous flow through circuit with resistance applied at exhalation valve Delivered by prongs or mask through most current ventilators (Servo I, PB 840, Drager Babylog, AVEA) Some companies have their own CPAP products (Drager) and others use universal types (Hudson, INCA, Argyle) CONVENTIONAL INFANT CPAP INTERFACES Argyle CPAP Prongs Neotech Long Prongs Hudson CPAP TYPES OF INFANT CPAP SYSTEMS Conventional CPAP Apparatus Drager BabyFlow CPAP Device CONVENTIONAL INFANT CPAP Advantages More cost effective; one device for CPAP or ventilation More costly if ventilation is not needed Disadvantages: Continuous flow CPAP delivery may increase WOB Pressure varies throughout respiratory cycle Ref: Moa and Nilsson 1988 TYPES OF INFANT CPAP SYSTEMS Bubble CPAP is probably one of the earlier methods of delivering CPAP Bubble CPAP Inspiratory Flow with expiratory limb placed in column of water Depth in centimeters equals cmH2O pressure Bubble CPAP CPAP made a resurgence into clinical practice in the late 1980’s Dr. Jen Tien Wung began using Bubble CPAP in the NICU Delivery Room at Columbia University in 1987 Avoidance intubation with early CPAP use Lower incidence of BPD and Chronic Lung Disease in neonates at Columbia compared to other NICU’s has been reported repeatedly Morley, et al (2008) randomly assigned 608 infants (25-28 weeks) to early NCPAP vs. intubation and ventilation. There was no difference in mortality or BPD Bubble CPAP: Newer Systems B&B BubblePAP Advantages of Bubble CPAP Simple, inexpensive setups Constant CPAP Pressure One study showed enhanced ventilation with bubble CPAP (oscillation effect) Subsequent studies showed dampening of pressure distally with no oscillation at lung periphery and no improvement in gas exchange TYPES OF INFANT CPAP SYSTEMS Variable Flow CPAP Initially introduced by Hamilton with the Aladdin CPAP System > Arabella Infant Flow by Viasys (CareFusion) How does Variable Flow CPAP work? Utilizes a specially designed nasal piece that uses fluidics to deliver flow Fluidic Flip Action Variable Flow CPAP During inspiration, flow is directed towards the infant During exhalation, flow is directed away from the infant Variable Flow CPAP Advantages Lower work of breathing as flow is available on patient demand Klausner, et al (1996) studied the Fluidic Flow Driver and showed reduced WOB by 75% compared to conventional CPAP Pandit, et al (2001) reported increase volumes and lower WOB Pressures are more stable throughout respiratory cycle Ref: Moa and Nilsson 1988 Variable Flow CPAP Circuit Expiratory Channel Intranasal Pressure Monitoring Twin Jet Injector Nozzles Gas Inlet Variable Flow CPAP Circuit SiPAP and Variable Flow CPAP What is SiPAP Delivers CPAP and inspiratory pressure (up to 10 cmH2O) Potential benefits Recruit lung volume Off-load respiratory work (Vt-3-6 ml/kg) Stimulate respiratory center SiPAP Clinical Trials Lista, et al, study (Milan, Italy, 2009) compared NCPAP (Group A) vs. Bi-level (Group B) using SiPAP device (total 40 patients) Preemies with AGA 30wks Mean Pressure 6 cmH2O Group A, 6cmH2O CPAP Group B, 8cmH2O high pressure and 4.5cmH2O low pressure Significantly longer need for ventilatory support (6.2 v. 3.4 days) and oxygen dependency (13.8 vs. 6.5 days) in CPAP vs. Bilevel group SiPAP Clinical Trials Moretti, et al (Italy, 2008) compared extubation to NCPAP vs. NIPPV 90% success in NIPPV vs. 61% in CPAP Failure of NIPPV related to the following: ELBW babies less than 750 grams unable to maintain ventilation and oxygenation Intubation after 72 hours due to micro-atelectasis Preemies with infection/sepsis High Flow Nasal Cannula Vapotherm High Flow Nasal Cannula System High Flow Nasal Cannula Fisher Paykel High Flow System High Flow Nasal Cannula What is the buzz about? Ease of use Better tolerated by baby Less trauma Heated humidity But is it CPAP? “Vapotherm devices are not Continuous Positive Airway Pressure devices and are not designed to deliver a set pressure. The technology is designed to deliver conditioned gas flows in an open system via a simple nasal cannula”, Dr. Miller, Director of Clinical Research and Education, Vapotherm. High Flow Nasal Cannula What Flow rates that exceed inspiratory flowrates without entrainment of room air is High Flow Therapy? Over 2 liters in infants and 6 liters in adults Optimal conditioning of gas for 99% relative humidity, while maintaining body temperature High Flow Nasal Cannula What are the physiologic benefits of High Flow Nasal Cannula? Enhanced respiratory efficiency by flushing out nasopharyngeal anatomical deadspace Minimizes inspiratory resistance with flows that meet or exceed the patient’s inspiratory flow Facilitates not only oxygenation, but carbon dioxide elimination Lowers resistive work of breathing Adequate warming of the airways improves conductance HFNC and Pressure What is the relationship between Pressure and Flow? Locke, et al (1993, Pediatrics) reported inadvertent pressure, even at low flows, with the use of prongs that are relatively large for the size of the nares Sreenan, et al (2001, Pediatrics) reported nasal cannula flow with relatively large prongs can generate up to 8 cm H2O pharyngeal pressure The amount of pressure generated is related to the amount of leak around the prongs and mouth Prongs ½ the diameter of the nares with open mouth generates very little pressure HFNC and Pressure What is the relationship between Pressure and Flow? Saslow and colleagues (2006, J Perinat), reported that at 8 liters of flow in the neonate, the pressure is not greater than 6 cmH2O Kubicka and colleagues (2008, Pediatrics), reported at 5 liters of flow with 0.2 cm OD cannula, pressure never exceed 5 cmH2O Author cautioned that use of larger cannula with closed mouth or use in infants less than 1000g may result in higher pressures Clinical Benefits of HFNC Many studies have shown positive clinical benefits of HFNC Sun (2004) in109 infants from <500g >1500g, reported no evidence of barotrauma, CPAP belly, nosocomial infection, nasal trauma, or nasal mucus plugging in infants treated with HFNC for mild to moderate RDS Shoemaker (2007), JPerinat, reported ventilator days decreased with use of HFNC, higher intubation rates with early CPAP compared to early HFNC in infants <30wks gestation Clinical Efficacy of HFNC Some studies have showed lack of efficacy with HFNC compared to CPAP Campbell and colleagues (2006), J Perinat, randomized 40 patients to either CPAP (5-6 cmH2O) or HFNC and reintubation rate in the HFNC group was 60% compared to 15% in the NCPAP group High Flow Nasal Cannula: Some Conclusions HFNC can produce positive airway pressure and this pressure is: Variable (may range from trivial to significant) Unpredictable Unregulated Related to flow, prong size, and patient size Use with caution in VLBW preemies (lower flows and smaller prongs) Sufficient to produce clinical effects and/or changes in pulmonary function High Flow Nasal Cannula: Other Conclusions HFNC should not be regarded as a form of CPAP, but rather as a distinct respiratory modality with its own merits HFNC is a more user friendly modality than CPAP and will continue to be widely used Well designed high quality studies are need to support the efficacy of HFNC in the neonatal patient and to clarify potential benefits vs. adverse consequences Clear as Mud? References Davis, PG: Non-invasive respiratory support of preterm neonates with respiratory distress: Continuous positive airway pressure and nasal intermittent positive pressure ventilation (Seminars in Fetal & Neonatal Medicine 2009) Polin, RA: Continuous positive airway pressure: Old questions and new controversies (2008, Journal Neonatl-Perinatal Medicine) References De Clerk:Humidified High Flow Nasal Cannula, is it the New and Improved CPAP? (Advances in Neonatal Care) Miller, T: High Flow Therapy and Humidification, a Summary of Mechanisms of Action, Thechnology, and Research (Vapotherm website) Questions????
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