Continuous Positive Airway Pressure.pptx

Continuous Positive Airway Pressure

1. JOURNAL CLUB BY: Dr.Sajid Noor F.C.P.S Trainee

2. Continuous Positive Airway Pressure: The Light that Really does Keep Monster from Baby Away Ravi Ambey , Priya Gogia Department of Pediatrics, Madhya Pradesh, India International Journal of Pediatrics Research and Practice ( Published: 10-07-2015 ) Review Article

3. INTRODUCTION CPAP is a continuously applied distending pressure (CDP) used for maintenance of an increased transpulmonary pressure during expiratory phase of respiration, in a spontaneously breathing patient.

4. Cont… It prevents the alveolar collapse with marginal stability. Better recruitment of alveoli thus increases the functional capacity of lungs . It result in less ventilator induced lung injury than mechanical ventilation, hence reduce incidence of chronic lung disease It is a simple, low- cost and effective method of ventilating a sick new born in resource restricted countries.

5. HISTORY Harrison 1968: described grunting in neonates as naturally producing end expiratory pressure Gregory et al, 1971: introduced the clinical use of CPAP in neonates.(via endotrachial tube or a head box) Later Kattwinkel reporte d successful use of nasal prongs in neonates with RDS.

6. OUTCOME Following the introduction of CPAP. The mortality of RDS decreased from 55-35% to 20-15% It has been documented that atelecto -trauma, bio-trauma and volu -trauma is less with CPAP An improvement which is comparable with the effect obtained by the introduction of surfactant 20 years later.

7. DISCUSSION

8. PRINCIPLE The exact mechanism is still unclear . Grunting in a baby with respiratory distress is an attempt to generate pressure against closed glottis that keeps the airway open during expiration. CPAP works on the same principle.

9. In a baby with hyaline membrane disease, forced residual capacity (functional residual capacity [FRC] - the volume of air that is remaining in lungs after tidal volume) is reduced below closing volume (volume below which the terminal bronchioles get closed). CPAP generates continuous pressure throughout the respiratory cycle to a point that FRC reaches above the closing volume, and terminal bronchioles remain patent throughout the respiratory cycle.

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

11. 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.

12. According to Laplace law… The pressure generated depends on surface tension, and inversely to the radius of the substance.

13. 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

14. How CPAP Works… In RDS, the lack of the surfactant allows the water molecules (lung fluid ) to coalesce and reducing the radius of the alveoli. Thereby, more pressure is required to open the collapsed alveoli. CPAP splints open the upper airway thus reduces the airway resistance and keeping the airway open by negotiating the surface tension.

15. How does CPAP works

16. Cont.. CPAP by generating the pressure also stimulates the “ Hering–Bruer’s ” reflex . It states that stretching of pleura during the end of expiration stimulates the respiratory center (in the brain stem). By this the next cycle of respiration is initiated.

17. Stretches lung pleura and upper airway CPAP MAGIC 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

18. Indications of CPAP in Neonates Hyaline membrane disease Apnea of prematurity Post- extubation in preterm VLBW Transient tachypnea of newborn Meconium aspiration syndrome Pneumonia Pulmonary edema/pulmonary hemorrhage Laryngomalacia / tracheomalacia / bronchomalacia .

19. Contraindications of CPAP in Neonates Patients with poor respiratory efforts Trachea-esophageal fistula Congenital diaphragmatic hernia Nasal obstructions - choanal atresia , cleft palate When PaCO2>60 mmHg, Ph<7.2 Babies with cyanotic heart diseases Relatively the patients with the central cause of respiratory distress like sepsis, birth asphyxia, intracranial hemorrhages .

20. BASIC ESSENTIALS IN CPAP Every basic CPAP machine requires the following: 1 2 Gas source Pressure generator Continuous supply of warm humidified and blended mixture of air and oxygen Continuous positive pressure generation. The pressure generators are either continuous type (conventional stand - alone CPAP, bubble CPAP) or variable flow type (infant flow meter)

21. 3 Patients interface and circuit Connect the CPAP circuit to infant’s airway. The various types of interfaces are 1.Nasal prongs (single/ binasal ) 2. Nasopharyngeal prongs 3. Nasal cannula 4. Nasal masks

22. HOW THE INDIGENOUS CPAP (BUBBLE CPAP) WAS MADE? Bubble CPAP is a continuous flow type of CPAP pressure generator where the pressure is generated by immersing the variable length of expiratory limb in the water chamber. Bubble CPAP having its origin in 1960’s but its use never gained much popularity in developing countries because of cost and maintenance. The market cost of Indian bubble CPAP is between 50,000 and 80,000 rupees. In resource limited settings, every tertiary center cannot access to this life-saving machine.

23. Figure 1: Indigenous continuous positive airway pressure circuit (self- drawn diagram)

24. ESSENTIALS OF CPAP Before the initiation, the head end is elevated 30° via shoulder roll. 1. The flow of gases is adjusted according to clinical condition of the patient from 0 to 10 liters/min (usually kept between 5 and 8 cm L/min).

25. 2 .. There are two limbs in the circuit A. The inspiratory limb is the connection between flow meter and patient. It allows the compress blended air-oxygen to pass through humidefier and humidifies gases at 35-37°C B. The expiratory limb starts from the humidifier . There is bifurcation of the limb at this point. Through corrugated tubing one end attached to patients interface via nasal prongs and other end to intercostal chest drainage bag through ICTD tube. This tube is immersed in water up to required depth.

26. Cont.. 3. Set the desired flow and pressure. 4. At the patients interface binasal prongs are attached, which are supported with the head cap. It prevents the nasal injury due to the hanging pressure of prongs.

27. 5.The vitals were monitored and the pulse oximeter was attached. 6. An orogastric tube was inserted to decompress the stomach or can allow feeding of newborn on CPAP. 7. Nasal suction was regularly done, and both nostrils were moistened with normal saline at regular intervals.

28. 8.Look for bubbling in the water chamber. If no bubbling occurs any leak in the circuit has to be looked for. If no leak found then the flow is increased with 1 liter/mint.

29. THE FAILURE OF CPAP when with the pressure of 8cm H2O, and the flow of oxygen is 70%. The PH of baby is below 7.2. It is the time when mechanical ventilation is to be considered

30. CPAP failure was defined as…. SpO2 <88% on FiO2 >60% for >30 minutes (with requirement of CPAP>8cms of H2O) Blood gases showing PH <7.20 PCO2 ≥ 65 mmHg PO2 <50 mm Hg on FiO >60% Pathologic apnea Increasing Retractions Ref: Indian Journal of Neonatal Medicine and Research. 2015 April

31. MONITORING DURING THE PROCEDURE Vitals - temperature, heart rate, capillary refill time,pulse oximetry (89-94%), blood glucose. Respiratory distress score - Silverman for preterm or Downe’s score for term Monitor blood pressure, urine output, and abdominal girth. Arterial blood gas analysis Look for nasal trauma, moniter the dryness of nose.

32. Score: > 4 = Clinical respiratory distress; monitor arterial blood gases > 8 = Impending respiratory failures

33. A score greater than 7 indicates that the baby is in respiratory failure.

34. Cont.. Patient has to repositioned every 3 hr with neck slightly extended to maintain airway Humidification of the gases should be checked regularly. The circuit has to be regularly checked for leakage

35. Cont.. The tubings must be regularly cleaned and checked for blockage. There is no need of daily regular chest X-ray in monitoring of lung signs Maintain hydration of the baby Keep the resuscitation equipment cot side all the times. Neurological assessment .

36. WEANING OFF FROM CPAP After proper monitoring when there are no signs of respiratory distress (resolution of grunting, nasal flaring, and chest retractions) and arterial blood gas analysis is within normal limits. FiO2 is gradually decreased in steps of 5% and pressure decreased by 1 cm H2O. Make sure the baby breathes with less effort.

37. COMPLICATIONS OF CPAP Air leaks ( pneumothorax ) Agitation CPAP belly syndrome Nasal trauma Hypotension Increased pulmonary vascular resistance Chronic lung disease.

38. CPAP BELLY Abdominal distension can occur in babies on CPAP.It is compounded by presence of immature gut in preterms and some decrease in blood flow to the gut. All these together lead to what is called as ‘CPAP belly syndrome’

39. RESULTS Study was conducted on 70 newborns ,32weeks. Majority of the cases received bubble CPAP. The incidence of CPAP failure was 30%. The proportion of neonates who required surfactant was 18.6%. Who developed ROP was 37.1% who met with mortality was 7.1% Nasal Trauma, Hypotension, Intra Ventricular Hemorrhage and CPAP belly were the most common complications, occurring in 80% No case of pulmonary hemorrhage was reported. Ref: Indian Journal of Neonatal Medicine and Research. 2015 April

40. CONCLUSION CPAP is now-a-days considered as a first line therapy for management of RDS in preterm infants. Currently, the use of CPAP is increasing due to the advantage of being less expensive, less damaging and having reduced incidence of the chronic lung disease and broncho -pulmonary dysplasia over the use of invasive mechanical ventilation. It is an extension of ventilatory support rather than replacement of mechanical ventilation.

41. THANKS