MECONIUM STAINED AMNIOTIC FLUID DELIVERY.

TO INTUBATE OR NOT ?

 

Dr Rhishikesh Thakre

DM(Neo),MD(Ped),DNB,FCPS,DcH.

 

 

INTRODUCTION :

Meconium aspiration syndrome ( MAS ) remains one of the most common causes of neonatal respiratory distress. Meconium is more potent and toxic than we previously have appreciated. The vicious cycle of hypoxemia, shunting, acidosis and pulmonary hypertension is frequently associated with MAS and may be difficult or impossible to treat successfully. Therefore the aim of intervention in the delivery room should be directed to reduce the incidence and severity of meconium aspiration. On the basis of evidence from non randomized studies, it has been recommended that all babies born through thick meconium should have their trachea intubated so that suctioning of their airways can be performed. With growing research there is ongoing debate concerning universal versus selective intratracheal suctioning in MSAF deliveries.

This article reviews the current evidence for babies born through meconium stained amniotic fluid and their need for intubation for suctioning the airways.

 

 

UNIVERSAL INTRATRACHEAL SUCTIONING :

 

·                    Intubation of the treacheas of meconium stained babies at birth has been advocated as a means of preventing or ameliorating severe meconium aspiration syndrome based on three non-randomized studies. The rationale was careful aspiration of the airway at birth reduces both the incidence and severity of meconium aspiration syndrome.

           These studies1,2,3. have suggested that when thick meconium staining has occurred the obstetrician should suck out the mouth as the head crowns, using either a suction catheter or a bulb suction. Gregory et al1 found that 56% of meconium stained infants had meconium in the trachea and in 10% there was meconium below the cords despite it being absent from the mouth or pharynx.

1.Gregory GA, Gooding CA, Phills RH, et al Meconium aspiration in infants: a prospective study. J Pediatr  85: 848-852,1974.

2.Ting P, Brady JP. Tracheal suction in meconium aspiration. Obstet Gynecol  122 : 767-771,1975.

3.Carson BS, Losey KW, Bowes WA et al. Combined pediatric and obstetric approaches to prevent meconium aspiration syndrome. Am  J Obst Gynec  126: 712-715,1976.

 

·                    All recent reports concerning the role of endotracheal intubation in MSAF babies have  found a substantial proportion of infants who developed MAS (26% - 96%) had not been intubated and suctioned in the delivery room .4,5,6,7,8,9.

 

4.Usta IM, Mercer BM, Aswad NK et al : The Impact of  policy of amnoinfusion of meconium stained ammiotic fluid. Obstet Gynecol 85: 237, 1995.

5. Bhutta JA, Jalil S : Meconium aspiration syndrome : the role of resuscitation and tracheal suction in prevention. Asia Oceania J Obstet Gynecol 18:13; 1992.

6.Chistly AL, Alvi Y, Iftikhar M et al : Meconium aspiration in  neonate combined obstetric and pediatric intervention improves outcome. J Pakistan Med Assoc 46: 104, 1996.

7.Erekkola R, Kero P, Sucbhonen Polvi H et al : Meconium aspiration syndrome. Ann Chir Gynecol 83: 106, 1994.

    8.Halliday HL, Speer CP, Roberton B, et al : Treatment of severe meconium aspiration syndrome with porcine surfactant . Eur J Pediatr 155: 1047, 1996.

9.Manickam D : A retrospective review of tracheal suction at birth in  neonates with meconium aspiration syndrome. Med J Malaysia 47; 60, 1992.

 

·                    The current guidelines of the American Academy of Pediatrics and American Heart Association recommend intubation of all infants born through moderately thick or thick consistency MSAF10.

 

10.Committee on neonatal ventilation meconium / chest compression. Guidelines proposed at the 1992 National Conference on Cardiopulmonary Resuscitation and Emergency Cardiac Care; Dallas 1992.JAMA 268; 2276, 1992.

 

 

 

SELECTIVE INTRATRACHEAL SUCTIONING :

 

·                    Several authors11,12,13 have retrospectively reviewed delivery room management in their institutions and concluded that a selective approach to intubation, generally restricted to depressed infants is justified.

 

11.Gupta V, Bhatia BD, Mishra OP. Meconium stained amniotic fluid : Antenatal, Intrapartum and neonatal attributes. Ind Ped 33: 293; 1996.

12.Peng TCC, Gutcer CK, VanDorsten JP. A selective aggressive approach to neonate exposed to meconium stained ammotic fluid.Am J Obst Gynecol 175: 296, 1996.

13.Yoder BA : Meconium Stained amniotic fluid and respiratory complications. Impact of selective tracheal  suction. Obstet Gynecol 83; 77: 1994.

 

 

·                    Linder et al 14 (1988) studied 572 meconium stained babies which were divided into intervention group and control group. Suction of the baby’s mouth and nose was performed while the head was on perineum in all. Half of the team of pediatricians who participated in the study were to intubate and suction all MSAF babies during their attendance at birth whilst the other half was instructed to restrain from doing so. There were no respiratory complications in the conservatively managed meconium stained infants born at term.

 

14.Linder N, Aramda JA Tsur M et al : Need for endotracheal intubation and suction in meconium stained neonate. J Pediatr 1988; 112: 613-615

 

·                    Daga et al 15  examined the outcome of 49 babies born with thick meconium staining of the amniotic fluid. These were randomly allocated to either oropharyngeal suction or combined oropharyngeal suction and tracheal suction. The outcomes studied were pneumothorax, convulsions, HIE, duration of oxygen administration and mortality. Three babies developed pneumothorax requiring intercostal drainage, one in the tracheal suction group and two in oropharyrngeal suction group.

 

15.Daga SK, Dave K, Mehta V et al : Tracheal suction in meconium stained infants : a randomized controlled study. J trop Pediatr 1994; 40: 198-210.

 

·                    Liu 16 (1998) studied whether intubation of the low risk newborn through meconium affects the incidence of respiratory symptoms or not. 2 of the 77 infants in the intubation group developed respiratory symptoms and one of these needed oxygen compared to 1 of 92 infants in the non intubated group who developed symptoms but did not need oxygen.

 

16.Liu WF. Delivery room intubation of thin meconium in the low risk newborn : a clinical trial. Paediatr Res 1998; 43: 182A

 

·                    Wiswell et al 17(2000) studied the delivery room management of the apparently vigorous meconium stained neonate in a multicentre, international collaboration trial involving 1051 infants. 34 of 7051 infants in the intubation group developed meconium aspiration syndrome compared to 28 of 1043 in the expectant management group. There were no significant differenes between groups in the occurrence of MAS or in the development of other respiratory disorders. They concluded “Compared with expectant management intubation and suctioning of the apparently vigorous meconium stained infant does not result in a decreased incidence of MAS or other respiratory disorders. Complications of intubation are infrequent and short lived.”

 

17.Wiswell JE, Gammon CM, Jacol J et al ; Delivery room management of the apparently vigorous meconium stained neonate. Results of the multicentre international collaborative trial. Pediatric Vol 105, No l, Jan 2000, 1-7.

 

Meta-analysis of these studies does not support routine use of endotracheal intubation at birth in vigorous meconium stained babies.

 

DISCUSSION

 

Meconium first appears in the fetal ileum between 10 and 16 weeks of gestation as a viscous, green liquid composed of gastrointestinal secretions, cellular debris, bile and panrcreatic fluid, mucous, blood, lanugo, and vernix. Meconium is approximately 72% to 80% water. MSAF rarely occurs before 38 weeks of gestation. The increased incidence of MSAF with advancing gestational age probably reflects the maturation of peristalsis in the fetal intestine. Intestinal parasympathetic innervention and myelination also increase throughout gestation and may play a role in the amplified passage of meconium in late gestation. Most infants with MSAF do not have lower Apgar scores, more acidosis or clinical illness than infants born with clear amniotic fluid. Perinatal morbidity is increased in newborns with abnormal fetal heart rate patterns in the intrapartum period.

Before the late 1970’s it was thought that aspiration of amniotic fluid and meconium occurred during the first few breaths after delivery. Meconium aspiration syndrome continues to occur in those who are adequately suctioned in the delivery room indicating that in some infants, especially those with asphyxia, in-utero aspiration takes place. Clinically fetal lung fluid flows outward from the lungs into the amniotic sac. However studies with radioopaque contrast and Cr labelled erythrocytes injected into the amniotic sac demonstrated that some amniotic fluid enters the fetal lung in the nonasphyxiated human fetus. Gasping associated with inhalation of amniotic fluid or meconium occurs in fetal lambs, rhesus monkeys, and humans in response to fetal asphyxia induced by compression of the umbilical cord or aorta.

 

FETAL GASPING MAY BE A CRITICAL FACTOR IN THE ENTRY OF MECONIUM INTO THE LUNG BEFORE BIRTH. ANTENATAL DIAGNOSIS  AND TREATMENT OF ASPHYXIA IS CRITICAL FOR PREVENTION OF MAS.

 

Clinical studies support the use of intrapartum amnioinfusion, particularly in cases of oligohydramnios to decrease the rate of emergency cesarean section as well as to decrease morbidity related to MAS.

 

Routine oropharyngeal suctioning before delivery of the infants shoulders has long played an important role in preventing MAS.

 

However following additional methods have been tried in an effort to prevent MAS.

1.                  Cricoid pressure involves applying pressure to the infants airway to prevent in intratracheal meconium from descending into the lungs.

2.                  Epiglotic blockage entails insertion of one or two fingers into  infants airway to manually close the epiglottis and block the entry of meconium.

3.                  Thoracic compression consists of encircling the childs chest with ones hands and applying pressure before endotracheal cleansing .

 

 All these are potentially dangerous and should be abandoned.

 

There is ongoing debate concerning universal versus selective intratracheal suctioning in meconium stained infants .With growing body of knowledge and our understanding, it is now clear that the management of MSAF babies is not decided by the consistency of meconium (thick or thin ) as was previously thought, but by the state of the neonate.

If  the neonate born through MSAF is depressed at birth, irrespective of the consistency of meconium he  in addition to the oropharyngeal suction at the perineum warrants intubation for intratracheal suctioning .Otherwise a vigorous neonate born through MSAF should not undergo intubation irrespective of the meconium consistency.

            With the meta-analysis of trials it is now clear that the outcome of babies born though MSAF at term and who are vigorous is not different in the intubated versus the conservatively managed group in terms of mortality, meconium aspiration syndrome, other respiratory symptoms or disorders, pneumothorax, oxygen need, stridor, HIE or convulsions

 

ROUTINE ENDOTRACHEAL INTUBATION AT BIRTH IN VIGOROUS TERM MECONIUM STAIED BABIES HAS NOT BEEN SHOWN TO BE BENEFECIAL AND SHOULD BE ABONDONED.

 

PRACTICAL POINTS :

 

1.                  Passage of meconium is physiological in breech deliveries and  postdated babies, but would be considered pathological any time if the fetal heart rate monitoring is associated with non reassuring fetal heart rate pattern.

2.                  Passage of meconium is extremely rare in preterms and its presence should consider diagnosis of listeria sepsis.

3.                  Majority of MSAF babies have  uneventful course unless complicated by abnormal fetal heart rate patterns.

4.                  Yellow meconium is usually old, while green meconium suggests a more recent insult.

5.                  The indication for intubation in MSAF babies is only for those who are depressed at birth irrespective of the consistency of meconium.

6.                  For infants requiring endotracheal suctioning, vigorous stimulation and drying maneuvers are delayed until intubation is performed to avoid initiation of respiration. After clearance of  the airway usual steps of resuscitation are performed.

7.                  Bag and mask ventilation is contraindicated in MSAF babies who are depressed at birth and intubation for intra tracheal suctioning takes precedence for airway clearance.

8.                  To date there are no data verifying the efficacy of chest physiotherapy either in preventing MAS or in treating the disorder.

9.                  To date there have been no prospective randomized controlled trials assessing the potential benefits of cesarean versus vaginal delivery in preventing MAS.

10.              Negative pressure during suctioning of airway should not exceed - 120mm of Hg. It should be applied continously and not intermittently for  optimal retrieval.

11.              An intriguing therapy is that of dilute surfactant  lavage which has been found to be beneficial in human infants with established MAS.

 

 

 

 

 

 

 

PROTCOL FOR MANAGEMENT OF MSAF BABIES

 

MSAF baby.

Suction oropharynx at perineum

 

 

 


Active Depressed

 No ET           Intubation

 

 

 

 

 

 

 -SKIP INITIAL STEPS OF STABILIZATION. 

   (DRYING/STIMULATION)

 -INTUBATE THE BABY, SINGLETIME.

 -SUCTION AIRWAY WITH CONTINOUS PRESSURE NOT 

  EXCEEDING – 120 mm of Hg TO RETREIVE AS MUCH 

  MECONLUM AS POSSIBLE

 -APPLY SECOND INTERVAL OF NEGATIVE PRESSURE IF 

  MECONIUM IS STILL RETRIEVED.

- ASSESS FOR BREATHING AND HEART RATE TO DECIDE

  FURTHER RESUSCITATION.

- DO NOT BAG THE BABY UNLESS AIRWAY IS CLEARED.

-ATTEMPTS AT INTUBATION SHOULD NOT TAKE MORE 

 THAN 20 SECONDS.

-SUPPLEMENT WITH OXYGEN AT TIME OF INTUBATION.

-DO NOT OVERLOOK THE INFANTS GENERAL CONDITION.

-IF UNSUCCESSFUL THE CHILD’S CONDITION SHOULD BE ASSESSED AND MANEUVERS SUCH AS STIMULATION AND POSITIVE PRESSURE VENTILATION BE UNDERTAKEN IF NEEDED.

 

 

 

 

 

 

Do’s   

 

1.                  Oropharyngeal suction at perineum in all MSAF babies.           

2.                  Intraparttum fetal heart rate monitoring in all MSAF babies.

3.                  Anticipate passage of meconium or MAS during birth of all IUGR babies in the labor room.

4.                  Skillfull resuscitation and assistance are keypoints in management.

5.                  Do intubate neonates born through MSAF who are depressed at birth irrespective of consistency of meconium.

6.                  Do intubate neonates born through MSAF who are depressed at birth irrespective of consistency of meconium.

7.                  Do intubate neonates born through MSAF who are depressed at 

     birth irrespective of consistency of meconium.

8.                  Do intubate neonates born through MSAF who are depressed at  

     birth irrespective of consistency of meconium.

 

 

 

Dont’s

 

1.                  Do not go by the consistency of meconium in management for intubation.

2.                  Do not apply cricoid pressure, chest compression or occlude airway by fingers to prevent initation of respiration in MSAF babies.

     3.  Do not ignore the general condition of baby during intubation.

 

Conclusions :

 

1.                  ROUTINE INTUBATION OF VIGOROUS TERM MECONIUM STAINED BABIES TO ASPIRATE THE LUNGS SHOULD BE ABANDONED.

 

2.                  SUCTIONING OF THE OROPHARYNX MAY BE BENEFICIAL BUT ENDOTRACHEAL INTUBATION SHOULD BE RESERVED FOR DEPRESSED OR NON VIGOROUS INFANTS.

 

Email :  rhishikeshthakre@hotmail.com

 

References

*Cleary GM, Wiswell TE: Meconium Stained amictic fluid and the meconium aspiration syndrome : An Update. Pediatr Clin North Am 45: 511, 1998.