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Meconium Aspiration Syndrome
Meconium aspiration syndrome (MAS) occurs when meconium, the first intestinal discharge of newborns, is breathed into the lungs before or during birth. It can cause respiratory distress in newborns. The document defines MAS and discusses the incidence, causes, pathophysiology, clinical features, diagnosis, prevention, management, complications, and prognosis of the condition. MAS is managed through supportive care in the neonatal ICU including respiratory support, antibiotics, and surfactant therapy. The prognosis depends on the severity of symptoms and associated complications such as brain damage or persistent pulmonary hypertension.
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Meconium Aspiration Syndrome
- 3. MECONIUM ASPIRATION SYNDROME PRESENTED BY: REENABHAGAT MN 1ST YEAR, 2017 LNC, PAHS
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- 5. Objectives: Introduction ofmeconium Definition of MAS Incidence Causes Pathophysiology Clinical Features Diagnostic Evaluation Prevention Management Complication Prognosis
- 6. Introduction of meconium The first intestinal discharge from newborns is meconium, which is a viscous, dark-green substance composed of intestinal epithelial cells, lanugo, mucus and intestinal secretions( eg. bile). Meconium is typically passed for 2-3 days after birth. Sometimes, the fetus passes the meconium while it is still in the womb. Intestinal secretions, mucosal cells and solid elements of swallowed amniotic fluid are the major solid constituents of meconium.
- 8. Definition of MAS Meconium aspiration syndrome( MAS) is a respiratory distress in a newborn who has breathed( aspirated) meconium into the lungs before or around the time of birth.
- 10. Incidence: A studyconducted in Australia and New Zealand in infants who were intubated and mechanically ventilated with a primary diagnosis of MAS between 1995 and 2002 showed that MAS occurred in 0.43 of 1,000 live births. The possibility of inhaling meconium occurs in about 5- 10% of births. Not all infants with meconium aspiration will develop MAS. Features of MAS develop immediately after birth only in 5-10% infants.( Dutta 2006)
- 11. Finding froma study at Manipal College of Medical Science, Pokhara, Nepal showed that: incidence of meconium stained amniotic fluid( MSAF) was 13.97% and that of MAS was 8.57%. Most common and significant risk factor associated with MAS were increased gestational age, increased cesarean section(LSCS) and low apgar score at 1min & 5 min. ( Swain & Thapalial, 2008)
- 13. Causes of MAS Hypoxia in distressed baby Meconium Stained Liquor Uterine Infections Difficulty during labour process
- 14. Factors that promotethe passage of meconium in utero includes the following: Placental insufficiency Post dated pegnancy Maternal hypertension Pre-eclampsia Oligohydramnios Maternal drug abuse, especially of tobacco and cocaine Maternal infection/ chorioamnioitis Fetal gasping secondary to hypoxia( fetal distress) Inadequate removal of meconium from the airway prior to the first breath.
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- 16. Airway Obstruction Completeobstruction of lungs may result in atelectasis. Partial obstruction cause: air trapping and hyperdistension of alveoli, commonly called ball-valve effect.
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- 19. History Presenceof meconium in amniotic fluid. Green urine may be observed in newborns with meconium aspiration syndrome less than 24 hours after birth. (Meconium pigments can be absorbed by the lungs and can be excreted in urine). Signs: Severe respiratory distress may be present.
- 20. Symptoms includethe following: Cyanosis End-expiratory grunting Nasal flaring Breathing problems like( difficulty in breathing, no breathing and rapid breathing) Intercostal retractions Tachypnea Barrel chest in the presence of air trapping Auscultated rales and rhonchi ( in some cases). Yellow-green staining of fingernails, umbilical cord and skin my be observed.
- 21. Diagnosis of MAS High risk infants may be identified by fetal tachycardia bradycardia or absence of fetal accelerations (upon CTG ) in utero At birth, the infant may look cachexic and show signs of yellowish meconium staining on skin, nail and the umbillical cord. These infants usually progress onto Infant Respiratory distress syndrome within 4 hours.
- 22. Investigations whichcan confirm the diagnosis are : Fetal chest x-ray, which will show hyperinflation, diaphragmatic flattening, cardiomegaly, patchy atelectasis and consolidation. ABG samples, which pH, partial pressure of oxygen( p02), partial pressure of CO2 ( pCO2) and continuous measurement of oxygenation by pulse oximetry are necessary for management.
- 23. Complete bloodcount: hemoglobin & hematocrit level must be sufficient to ensure adequate oxygen- carrying capacity. Serum electrolytes: obtain sodium, potassium and calcium concentration when the infants with MAS aged 24 hrs because the syndrome of inappropriate secretion of antidiuretic hormone( SIADH) and acute renal failure are frequent complications of perinatal stress.
- 24. Preventive measures ofMAS MAS is difficult to prevent. When there is meconium stained liquor, careful suctioning of posterior pharynx after delivery of head decreases the potential for aspiration of meconium. When aspiration occurs, intubation and immediate suctioning of airway can remove much of aspirated meconium. Do not perform the following harmful techniques in an attempt to prevent aspiration of meconium- stained liquor: - Squeezing of the chest of baby -Inserting a finger into the mouth of baby.
- 25. Management of MAS Prenatal: 1.Identification of high risk pregnancies - recognition of predisposing maternal factors - post dates pregnancy inductions as early as 41 weeks 2. Monitoring - careful observation and fetal monitoring during labour - corrective measures should be undertaken in identifies compromised fetus. 3. Amnioinfusion - relieved umbilical cord compression during labor -> reducing occurrence of variable fetal heart rate decelerations - efficiency not well demonstrated.
- 26. Delivery room management Anticipatethe worst…. Be prepared…
- 27. Immediate Management The AmericanAcademy of Pediatrics Neonatal Resuscitation Program Steering Committee guidelines are as follows If the baby is not vigorous: Suction the trachea immediately after delivery Suction for no longer than 5 seconds If no meconium is retrieved, do not repeat intubation and suction If meconium is retrieved and no bradycardia is present, reintubate and suction If the heart rate is low, administer positive pressure ventilation and consider suctioning again later. If the baby is vigorous: Do not electively intubate Clear secretions and meconium from the mouth and nose with a bulb syringe or a large-bore suction catheter. Dry, stimulate, reposition, and administer oxygen as necessary. Transfer ill newborns with respiratory distress to NICU
- 28. General management Continued carein the neonatal ICU (NICU) Maintain an optimal thermal environment Minimal handling to reduce agitation thus pulmonary hypertension and right-to-left shunting causing hypoxia and acidosis Insert umbilical artery to monitor blood pH and blood gases without agitating the infant. Continue respiratory care: oxygen therapy via hood or positive pressure is crucial in maintaining adequate arterial oxygenation. Oxygen saturation ( 90-95%) should be maintained. Newborns are treated with antibiotics because of risk of infection( eg. Gentamycin)
- 29. Supportive treatment o IVDextrose to prevent hypoglycemia. o Fluid restriction (60-70 mL/kg/d) to prevent cerebral and pulmonary edema o Electrolytes to correct metabolic acidosis o Protein, lipids, and vitamins to prevent deficiencies For treatment of persistent pulmonary hypertension of newborn( PPHN), inhaled nitric oxide is the pulmonary vasodilator of choice.
- 30. Surfactant Therapy: Replacedisplaced or inactivated surfactant and as a detergent to remove meconium, may reduce the severity of disease, progression to extracorporeal membrane oxygenation and decrease length of hospital stay. May decrease respiratory failure with MAS within 6 hrs of 3 doses ECMO: Extracorporeal membrane oxygenation is the last option focused on the function of oxygenation and CO2 removal. Effective but associated with a high incidence of poor neurologic outcomes. ECMO is done using only cervical cannulation, which can be performed under local anesthesia used for longer-term support ranging from 3-10 days.Allow time for intrinsic recovery of the lungs and heart. Survival rate 93-100%
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- 32. Complications of MAS In mild cases, respiratory distress usually subsides in 2-4 days although tachypnea can persist for longer. Cerebral hypoxia may lead to long term neurological damage. Aspiration pneumonia Brain damage due to lack of oxygen Collapsed lung Persistent pulmonary hypertension of newborn.
- 33. Prognosis of MAS The mortality rate of meconium-stained infants is considerably higher than that of non-stained infants. Meconium aspiration accounts for a significant proportion of neonatal deaths. Residual lung problems are rare but include symptomatic cough, wheezing, and persistent hyperinflation for up to five to ten years. The ultimate prognosis depends on the extent of CNS injury from asphyxia and the presence of associated problems such as persistent pulmonary hypertension. Mortality rate is approx 5%.
- 36. References: Ranabhat, R.D& Niraula, H.(2017) A textbook of midwifery & reproductive health (1st ed.). Kathmandu, Page no: 580- 582 Tuitui, R. (2016) Manual of midwifery III (11th ed.). Vidyarthi Pustak Bhandar, Kathmandu, Page no: 227-231 Dutta, D.C. (2011). A textbook of obstetrics including perinatology and contraception (7th ed.). A central book agency(P) ltd., Hyderabad, page no: 476