To determine the efficacy of clearing the trachea (windpipe) of meconium by introducing a tube into the windpipe (intubation), and suction at birth in babies who are born through the meconium-stained amniotic fluid and are depressed (identified by not breathing or limp or low heart rate) at birth.
Meconium is a thick green tar-like substance, that lines a baby's intestines during pregnancy. Meconium contains various intestinal enzymes and substances (blood, skin cells, etc.) ingested by the foetus. Meconium is usually first passed within 24 hours after birth. However, in certain circumstances when blood or oxygen supply to the foetus is compromised or the pregnancy extends beyond the normal period of 40 weeks, meconium passage may occur before birth. Once passed, meconium may be breathed (aspirated) in from amniotic fluid into the airways either before birth or with the first few breaths after birth. This can cause airway obstruction and inflammation of lung tissue from toxins (chemical pneumonia). Nearly 10% to 25% of births are complicated by meconium passage before birth and of these, 5% to 12% of neonates develop meconium aspiration syndrome (MAS). MAS can present with varying degrees of severity, from mild distress to life-threatening respiratory failure. One approach to prevent MAS is to identify babies who are depressed at birth, and clear the meconium from the airway before the baby takes their first breath. In this process, an endotracheal tube is inserted into the upper trachea and pulled out while the trachea is being suctioned. However, this may not prevent MAS if the baby has already aspirated meconium before being born. In addition, most of the babies who are candidates for this intervention need prompt resuscitation, and conducting tracheal suction has the potential to cause harm by delaying the initiation of artificial breaths.
We included four studies (581 neonates) conducted in hospitals in India. Three trials included neonates born at and beyond term gestation, whereas one included neonates born at and beyond 34 weeks of gestation. All four studies identified eligible neonates by the presence of at least one of the following at birth: no breathing or crying, poor muscle tone, and heart rate less than 100 beats per minute. The intervention consisted of tracheal suction at the time of birth with an intent to clear the trachea of meconium before regular breathing efforts began. Neonates in the control group were resuscitated at birth with no effort made to clear the trachea of meconium.
The search was up-to-date to 25 November 2020.
We are uncertain as to the effect of tracheal suction in reducing the risk of MAS. For every 1000 neonates in whom tracheal suction is done, MAS may be observed in 70 fewer to 80 more neonates. Similarly, we are uncertain as to the effect of tracheal suction on the risk of death before discharge from the hospital (22 fewer to 92 more per 1000 neonates). We are also uncertain as to the effect of tracheal suction on the risks of other outcomes, such as the need for advanced resuscitation measures; encephalopathy (brain damage or disease) due to asphyxia (a lack of oxygen that results in unconsciousness and often death); the need for or duration of mechanical ventilation; the need for non-invasive respiratory support (a mask); duration of oxygen therapy; and duration of hospitalisation. These and other complications of MAS were not different with or without tracheal suction.
Certainty of evidence
There was very low certainty evidence from the four studies included in this review. Firstly, in most of the studies, the healthcare workers who provided the clinical care or decided the presence of outcomes were aware of the study group assignment of the babies, thus increasing the risk of bias. Secondly, due to the small size of the studies and the low incidences of the outcomes, we had low confidence in ruling out clinically important benefits or harms when tracheal suction was performed. One study awaits classification and could not be included in the review. More research from well-conducted large trials is needed to conclusively answer the research question.
We are uncertain about the effect of tracheal suction on the incidence of MAS and its complications among non-vigorous neonates born through MSAF. One study awaits classification and could not be included in the review. More research from well-conducted large trials is needed to conclusively answer the review question.
Neonates born through meconium-stained amniotic fluid (MSAF) are at risk of developing meconium aspiration syndrome (MAS). Neonates who are non-vigorous due to intrapartum asphyxia are at higher risk of developing MAS. Clearance of meconium from the airways below the vocal cords by tracheal suction before initiating other steps of resuscitation may reduce the risk of development of MAS. However, conducting tracheal suction may not only be ineffective, it may also delay effective resuscitation, thus prolonging and worsening the hypoxic-ischaemic insult.
To evaluate the efficacy of tracheal suctioning at birth in preventing meconium aspiration syndrome and other complications among non-vigorous neonates born through meconium-stained amniotic fluid.
We used the standard search strategy of Cochrane Neonatal to search Cochrane Central Register of Controlled Trials (CENTRAL 2020, Issue 11) in the Cochrane Library; Ovid MEDLINE(R) and Epub Ahead of Print, In-Process & Other Non-Indexed Citations, Daily and Versions(R) (1946 to 25 November 2020) for randomised controlled trials (RCTs) and quasi‐randomised trials. We also searched clinical trials databases and the reference lists of retrieved articles for RCTs and quasi-randomised trials (up to November 2020).
We included studies enrolling non-vigorous neonates born through MSAF, if the intervention being tested included tracheal suction at the time of birth with an intent to clear the trachea of meconium before regular breathing efforts began. Tracheal suction could be performed with an endotracheal tube or a wide-gauge suction catheter. Neonates in the control group should have been resuscitated at birth with no effort made to clear the trachea of meconium.
Two review authors independently assessed trial quality and extracted data, consulting with a third review author about any disagreements. We used standard Cochrane methodological procedures, including assessment of risk of bias for all studies. Our primary outcomes were: MAS; all-cause neonatal mortality; and incidence of hypoxic-ischaemic encephalopathy (HIE). Secondary outcomes included: need for mechanical ventilation; incidence of pulmonary air leaks; culture-positive sepsis; and persistent pulmonary hypertension. We used the GRADE approach to assess the certainty of evidence.
We included four studies (enrolling 581 neonates) in the review. All four studies were conducted in tertiary care hospitals in India. Three of the four studies included neonates born at and beyond term gestation, whereas one included neonates born at and beyond 34 weeks of gestation. Due to the nature of the intervention, it was not possible to blind the healthcare personnel conducting the intervention.
Tracheal suction compared to no suction in non-vigorous neonates born through MSAF
In non-vigorous infants, no differences were noted in the risks of MAS (RR 1.00, 95% CI 0.80 to 1.25; RD 0.00, 95% CI -0.07 to 0.08; 4 studies, 581 neonates) or all-cause neonatal mortality (RR 1.24, 95% CI 0.76 to 2.02; RD 0.02, 95% CI -0.03 to 0.07; 4 studies, 575 neonates) with or without tracheal suctioning. No differences were reported in the risk of any severity HIE (RR 1.05, 95% CI 0.68 to 1.63; 1 study, 175 neonates) or moderate to severe HIE (RR 0.68, 95% CI 0.43 to 1.09; 1 study, 152 neonates) among non-vigorous neonates born through MSAF. We are also uncertain as to the effect of tracheal suction on other outcomes such as incidence of mechanical ventilation (RR 0.99, 95% CI 0.68 to 1.44; RD 0.00, 95% CI -0.06 to 0.06; 4 studies, 581 neonates), pulmonary air leaks (RR 1.22, 95% CI 0.38 to 3.93; RD 0.00, 95% CI -0.02 to 0.03; 3 studies, 449 neonates), persistent pulmonary hypertension (RR 1.29, 95% CI 0.60 to 2.77; RD 0.02, 95% CI -0.03 to 0.06; 3 studies, 406 neonates) and culture-positive sepsis (RR 1.32, 95% CI 0.48 to 3.57; RD 0.01, 95% CI -0.03 to 0.05; 3 studies, 406 neonates). All reported outcomes were judged as providing very low certainty evidence.