Cpap

CPAP SCIENCE,WORKSHOP,THERAPY,PRACTICE,INDICATION,RDS,MSAL,

MAS,APNEA OF PREMATURITY,PNEUMONIA,SEPTICEMIA

1. CPAP- SCIENCE INDICATION AND APPLICATION PRESENTED BY DR NISHANT PRABHAKAR MD PEDIATRICS

2. DEFINITION Also called continuous distending pressure (CDP) Maintenance of an increased (positive) transpulmonary pressure during the inspiratory & expiratory phase of respiration in a spontaniously breathing baby. By which alveoli are kept open which increase the functional residual capacity(FRC) of the lungs resulting in better gas exchange.

3. HISTORY Harrison 1968: described grunting in neonates as naturally producing end expiratory pressure Gregory et al, 1971: introduced the clinical use of distending pressure in neonates.(via endotrachial tube or a head box) Kattwinkel reporte d successful use of nasal prongs in neonates with RDS. Reports of significant lower incidence of chronic lung disease from columbia university that used more CPAP as compared to north american centre have led to resurgence of interest in CPAP over the last 15 years.

4. PHYSIOLOGY OF CPAP Increases FRC Decreases V/Q mismatch Splints upper airway - airway resistance Increase tidal volume Decrease work of breathing Conserves surfectant Increase lung compliance

5. DISADVANTAGES OF CONVENTIONAL VENTILATION High pressure- Barotrauma Tidal volumes- Volutrauma Atelectotrauma Inflammation & infection- Biotrauma CV ruptures the interalveolar septa thus decrease the surface area of gas exchange despite increasing lung volume.

6. Effect of Ventilator on Preterm Lamb Lung At 0 hour 24 hour after ventilation Limitations of premature lung 1.Underdeveloped architect to hold the lung open 2.Thicker and few septa so less SA for gas exchange Pinkerton KE, et al J Appl Physiol , 1994

7. Preterm Lambs at 72 Hours Distal Airspace Wall Thickness - CV nCPAP

8. VENTILATOR INDUCED LUNG INJURY (VILI) Biotrauma with tube atelectotrauma

9. VENTILATOR INDUCED LUNG INJURY (VILI) Barotrauma Volutrauma

10. ADVANTAGE OF CPAP Effect on lung growth- increased protein and DNA

11. 2- increased lung compliance

12. PVR Increases at Lung Volumes Below and Above FRC PVR Lung Volume FRC HMD MAS

13. CPAP MAGIC Opens lung at FRC Keeps it open at minimum constant pressure least atelecto & barotrauma Pulmonary arterial pressure are least hence less V/Q mismatch less pressure required. No ET tube- no biotrauma

14. Larger alveolus r = 1.5 T = 3 P = (2 x 3) / 1.5 P = 4 Smaller alveolus r = 1 T = 3 P = (2 x 3) / 1 P = 6 CPAP Law of LaPlace : P = 2T/r P : pressure T : surface tension r : radius

15. How does CPAP works

16. Stretches lung pleura and upper airway CPAP Prevents collapse of alveoli with marginal stability Stabilizes the chest wall Splints open upper airway Improves pH Reduces airway resistance Recruitment of alveoli PaO2 PaCO2 Improves V/Q mismatch and reduces intrapulmonary shunt Increased alveolar surface area for gas exchange Maintains lung at FRC Reduces work of breathing Reduces mixed and central apnea Reduces obstructive apnea Stimulates stretch receptors

17. INDICATION OF CPAP COMMON Respiratory distress syndrome Apnea of prematurity (specially obstructive apnea) Post- extubation in preterm VLBW infants Transient tachypnea of newborn (TTNB) OTHER INDICATION Pneumonia Meconium aspiration/other aspiration syndrome Pulmonary edema/pulmonary hemorrhage Laryngomalacia / tracheomalacia / bronchomalacia

18. Early CPAP in RDS was proved to be more beneficial in the atelectatic disease lower peak pressure required in infants treated with CPAP enhance surfactant conservation reduce the need for IMV by 20%, except infants with birth weight <1500 g. improve mortality and decrease the incidence of BPD prevent need for prolong intubation which reduce the incidence of acquired subglottic stenosis

19. Failure of CPAP therapy in RDS very low birth weight infant late application of CPAP severity of RDS associated disease e.g. sepsis, hypotension infants with severe degree of extrapulmonary shunt (Fox and coworkers, 1977)

20. CPAP in apnea of prematurity the application of low-level CPAP decrease the incidence of apnea of prematurity (compared to other forms of stimulation) improve oxygenation stimulation or inhibition of pulmonary reflexes alveolar stabilization mechanical splinting of airway; reduce supraglottic resistance in both inspiration and expiration some investigators recommended the early use of CPAP as a preventive measure of apnea of prematurity

21. CPAP IN INFANTS WITH MAS pathology of meconium aspiration atelectasis large airway obstruction V/Q abnormalities application of low-to moderate level CPAP resolution of atelectasis stabilization of terminal airway incidence of pneumothorax : not increased precautions in case with PPHN

22. C0NTRAINDICATION OF CPAP Progressive respiratory failure with PaCO2 levels >60 mmhg and/or inability to maintain oxygenation (PaCO2 <50 mmHg) Certain congenital malformation of the airway ( choanal atresia , cleft palate, tracheoesophageal fistula, congenital diaphragmatic hernia,etc ) Severe cardiovascular instability (hypotension) Poor respiratory drive (frequent apnea and bradycardia ) that is not improved by CPAP.

23. ESSENTIALS OF CPAP

24. CPAP MACHINES An ideal CPAP delivery system consists of: A continuous supply of warm, humidified, blended gases at a flow rate of 2-3 times the infant minute ventilation. A device to connect CPAP circuit to infants airway. Means of creating a positive pressure in CPAP circuit.

25. CPAP DELIVERY SYSTEM Ventilator : ideal system to provide CPAP but very costly CPAP system : should have End expiratory pressure of 0-15 cm of water. Humidification of upto 100% Gas flow 5-8 L/min Warming of gases to 34-37˚c Blending oxygen-air mixture FiO2 0.21-1.0 Low noise compressor Compatibility to run days & weeks Reasonable cost

26. PATIENT INTERFACE FOR PROVIDING CPAP Nasal prongs 1-Fisher & paykel 2-Hudson 3-Argyl nasal prong

27. CPAP DEVICES

28. SETTING PRESSURE, FLOW & FiO2 Pressure - regulated by depth of immersion of expiratory limb(water level being constant).start with 5 cm water in case of RDS or pneumonia and 4 cm water for apnea management.(range- 4-8) Flow - it should be minimal to produce bubbling in the bubble chamber(2-5 L/min is sufficient) FiO2 - start with a FiO2 of 40 to 50% and after adjusting the pressure,titrate FiO2 to maintain SpO2 between 89% to 94%.

29. MONITORING ADEQUACY AND COMPLICATION OF CPAP

30. MONITORING THE INFANT CONDITION Recommended monitoring: Respiratory status (RR, work of breathing) Pre ductal oxygen saturation Cardiovascular status (HR, BP, perfusion) GI status (abdominal distention, bowel sounds) Neurological state (tone, activity, responsiveness) Thermoregulation (temp)

31. WEANING FROM CPAP It is considered when clinical condition for which CPAP was indicated is passive. e.g. in case of RDS we have to see for improvement in Silverman Anderson score i.e. if score is less than 4 we can try weaning

32. SILVERMAN ANDERSON SCORE Score >7 –respiratory failure Score 4-7 –respiratory distress

33. WEANING FROM CPAP CPAP for apnea may be removed after 24 -48 hrs of apnea free interval. If the baby is stable on CPAP,first wean off the oxygen in steps of 5% and then wean PEEP to minimum of 4cm in step of 1cm/change. When baby is in FiO2<30%, PEEP 4cm, with normal saturation and minimal retraction CPAP can be removed.

34. CPAP FAILURE CPAP failure is considered if FiO2 required is >60% and PEEP required is > 7cm of water. If baby is continuing to have retraction, grunting and apnea is considered fo mechanical ventilation. If PaO2<50%, SpO2<85%, and PaCO2>60% on CPAP with FiO2>60% and PEEP >7cm of water is also considered for mechanical ventilation.

35. BEFORE CONSIDERING CPAP FAILURE ENSURE THE FOLLOWING

36. Maintaining Optimal Airway Care: Humidification Maintain adequate humidification of the circuit to prevent drying of secretions. Adjust settings to maintain gas humidification at or close to 100%. Set the humidifier temperature to 36.8-37.3 o C.

37. Complications associated with bubble nasal CPAP ● Pneumothorax / PIE more in the acute phase not a contraindication for continuing CPAP ● Nasal obstruction Remove secretions and check for proper positioning of the prongs ● Nasal septal erosion or necrosis Keep prongs away from the septum ● Gastric distension Intermittent or continuous aspiration of the stomach ● Feeding intolerance

38. Preventing Complications: Gastric Distention NCPAP is not a contraindication to enteric feeding. Infants may experience mild abdominal distention during NCPAP delivery from swallowing air.

39. CPAP BELLY

40. Preventing Complications: Gastric Distention To prevent gastric distention: Assess the infant’s abdomen regularly Pass an oro -gastric tube to aspirate excess air before feeds q 2-4 hr An 8 Fr oro -gastric tube may be left indwelling to allow for continuous air removal

41. CASE STUDY Antenatal steroid Arrangement before birth

42. Exercise

43. Thank you