A selective aggressive approach to the neonate exposed to meconium-stained amniotic fluid

Effect of Endotracheal Suctioning on Infants Born through Meconium-Stained Amniotic Fluid: A Meta-analysis

OBJECTIVE

Meconium is a common finding in amniotic fluid and placental specimens, particularly in term and post-term pregnancies. The objective of this paper was to perform a meta-analysis to examine the impact of endotracheal suctioning on the occurrence of meconium aspiration syndrome (MAS), mortality, and complications.

STUDY DESIGN

PubMed, EMBASE, and the Cochrane library were systematically searched for comparative studies. Odds ratios (ORs), weighted mean differences (WMDs), and corresponding 95% confidence intervals (CIs) were used to compare the outcomes.

RESULTS

Twelve studies were included in the meta-analysis. There were no significant impacts of endotracheal suctioning on the occurrence of MAS (OR = 3.05, 95% CI: 0.48-19.56), mortality (OR = 1.25, 95% CI: 0.35-4.44), the need for mechanical ventilation (OR = 4.20, 95% CI: 0.32-54.72), the occurrence of pneumothorax (OR = 0.99, 95% CI: 0.34-2.85), persistent pulmonary hypertension of the newborn (PPHN), (OR = 1.31, 95% CI: 0.58-2.98), hypoxic-ischemic encephalopathy (HIE) (OR = 0.82, 95% CI: 0.52-1.30), and length of stay (WMD = -0.11, 95% CI: -0.99-0.77).

CONCLUSION

Routine endotracheal suctioning at birth is not useful in preventing MAS, mortality, mechanical ventilation, PPHN, HIE, and prolonged length of stay in neonates born through MSAF.

KEY POINTS

· Routine suctioning is not recommended for newborns.. · Endotracheal aspiration is not beneficial for MAS.. · Future research may focus on selected neonates..

[The evolution of approach in the resuscitation of neonates born with meconium-stained amniotic fluid: a tale of two countries, China and U.S.A., in the past 60 years]

Neonates born through meconium-stained amniotic fluid (MSAF) may develop complications including meconium aspiration syndrome, persistent pulmonary hypertension of newborn and death. The approach to the resuscitation of these neonates has significantly evolved for the past few decades. Initially, under direct visualization technique, neonates with MSAF were commonly suctioned below the vocal cords soon after delivery. Since 2015, Neonatal Resuscitation Program (NRP^®) of the American Academy of Pediatrics has recommended against "routine" endotracheal suctioning of non-vigorous neonates with MSAF but favored immediate resuscitation with positive pressure ventilation via face-mask bagging. However, the China neonatal resuscitation 2021 guidelines continue to recommend routine endotracheal suctioning of non-vigorous neonates born with MSAF at birth. This review article discusses the differences and the rationales in the approach in the resuscitation of neonates with MSAF between Chinese and American NRP^® guidelines over the past 60 years.

Impact of the Revised NRP Meconium Aspiration Guidelines on Term Infant Outcomes

OBJECTIVES

To evaluate the association of the Neonatal Resuscitation Program, Seventh Edition changes on term infants born with meconium-stained amniotic fluid (MSAF).

STUDY DESIGN

We evaluated the effect of no longer routinely intubating nonvigorous term infants born with MSAF in 14 322 infants seen by the resuscitation team from January 1, 2014 to June 30, 2017 in a large, urban, academic hospital.

RESULTS

Delivery room intubations of term infants with MSAF fell from 19% to 3% after the change in guidelines (P = <.0001). The rate of all other delivery room intubations also decreased by 3%. After the implementation of the Seventh Edition guidelines, 1-minute Apgar scores were significantly more likely to be >3 (P = .009) and significantly less likely to be <7 (P = .011). The need for continued respiratory support after the first day of life also decreased. Admission rates to the NICU, length of stay, and the need for respiratory support on admission were unchanged.

CONCLUSIONS

Implementation of the Neonatal Resuscitation Program, Seventh Edition recommendations against routine suctioning nonvigorous infants born with MSAF was temporally associated with an improvement in 1-minute Apgar scores and decreased the need for respiratory support after the first day of life. There was also a significant decrease in total intubations performed in the delivery room. This has long-term implications on intubation experience among frontline providers.

Tracheal suctioning of meconium at birth for non-vigorous infants: a systematic review and meta-analysis

CONTEXT

The International Liaison Committee on Resuscitation sought to review the initial management of non-vigorous newborns delivered through meconium stained amniotic fluid (MSAF).

OBJECTIVE

To complete a systematic review and meta-analysis comparing endotracheal intubation and suctioning to immediate resuscitation without intubation for non-vigorous infants born at ≥34 weeks gestation delivered through MSAF.

DATA SOURCES

Medline, EMBASE, the Cochrane Database of Systematic Reviews, and other registries were searched from 1966 to November 7, 2019.

STUDY SELECTION

Studies were selected by pairs of independent reviewers in 2 stages.

DATA EXTRACTION

Reviewers extracted data, appraised risk of bias, and assessed Grading of Recommendations Assessment, Development and Evaluation certainty of evidence for each outcome.

RESULTS

Four randomized controlled trials (RCTs) included 581 patients and one observational study included 231 patients. No significant differences were observed between the group treated with tracheal suctioning compared with immediate resuscitation for survival at discharge (4 RCTs; risk ratio [RR] = 1.01; 95 % CI, 0.96-1.06; p = 0.69; observational study; no deaths), hypoxic ischemic encephalopathy and meconium aspiration syndrome.

LIMITATIONS

The certainty of evidence was low for survival at discharge and very low for all other outcomes.

CONCLUSIONS

For non-vigorous newborns delivered through MSAF, there is insufficient evidence to suggest routine immediate direct laryngoscopy with tracheal suctioning.

PROSPERO

CRD42019122778.

CLINICAL TRIALS REGISTRATION

PROSPERO; CRD42019122778.

A Population-Based Study of Meconium Aspiration Syndrome in Neonates Born between 37 and 43 Weeks of Gestation

The epidemiology of meconium aspiration syndrome (MAS) in term neonates is described in a population-based retrospective study of data recorded for all births from 2000 to 2007 in a French region (Burgundy). Of the 132 884 eligible term newborns, the rate of meconium-stained amniotic fluid (MSAF) was 7.93%. The prevalence of severe MAS was 0.067% in the overall population. MAS rate was 0.11% at 37-38 weeks of gestation (WG), 0.20% at 39–41 WG, and 0.49% at 42-43 WG. Factors independently associated with severe MAS were identified by a case-control study, that is, thick meconium amniotic fluid, fetal tachycardia, Apgar score ≤3 at 1 minute, and birth in a level III facility. Our results confirm the high prevalence of MSAF after 37 WG but also show the low frequency of severe MAS in a period corresponding to the new international recommendations on the management of birth with MSAF.

The pros and cons of suctioning at the perineum (intrapartum) and post-delivery with and without meconium

Routine oronasopharyngeal suctioning (ONPS) of the infant at delivery is a common practice in the delivery room. ONPS is performed to remove lung fluid, meconium, or other secretions from the airway, thereby improving oxygenation and/or preventing aspiration. However, there are controversies regarding this practice, as it seems to be associated with complications. In the presence of clear amniotic fluid, routine ONPS in infants born vaginally and by cesarean section is associated with bradycardia, apnea, and delays in achieving normal oxygen saturations, with no benefit. Intrapartum ONPS and post-natal endotracheal suctioning of vigorous infants born through meconium-stained amniotic fluid (MSAF) does not prevent meconium aspiration syndrome (MAS). Although depressed infants born through MSAF are at risk of developing MAS, there is no evidence that endotracheal suctioning of these infants reduces MAS.

Obstetric approaches to the prevention of meconium aspiration syndrome

Meconium aspiration syndrome (MAS) is associated with increased risk for perinatal mortality and morbidities. To provide an overview of the advances in our knowledge concerning the obstetric approaches to the prevention of MAS. The evidence of the effectiveness of intrapartum surveillance, amnioinfusion, and delivery room management in the prevention of MAS are reviewed in the present paper. Meconium aspiration syndrome remains one of the most common but challenging conditions for obstetricians and pediatricians. The available evidence did not demonstrate a beneficial effect of either of obstetric strategies in the prevention of MAS.

The epidemiology of meconium aspiration syndrome: incidence, risk factors, therapies, and outcome

OBJECTIVE

We sought to examine, in a large cohort of infants within a definable population of live births, the incidence, risk factors, treatments, complications, and outcomes of meconium aspiration syndrome (MAS).

DESIGN

Data were gathered on all of the infants in Australia and New Zealand who were intubated and mechanically ventilated with a primary diagnosis of MAS (MASINT) between 1995 and 2002, inclusive. Information on all of the live births during the same time period was obtained from perinatal data registries.

RESULTS

MASINT occurred in 1061 of 2,490,862 live births (0.43 of 1000), with a decrease in incidence from 1995 to 2002. A higher risk of MASINT was noted at advanced gestation, with 34% of cases born beyond 40 weeks, compared with 16% of infants without MAS. Fetal distress requiring obstetric intervention was noted in 51% of cases, and 42% were delivered by cesarean section. There was a striking association between low 5-minute Apgar score and MASINT. In addition, risk of MASINT was higher where maternal ethnicity was Pacific Islander or indigenous Australian and was also increased after planned home birth. Uptake of exogenous surfactant, high-frequency ventilation, and inhaled nitric oxide increased considerably during the study period, with >50% of infants receiving > or =1 of these therapies by 2002. Risk of air leak was 9.6% overall, with an apparent reduction to 5.3% in 2001-2002. The duration of intubation remained constant throughout the study period (median: 3 days), whereas duration of oxygen therapy and length of hospital stay increased. Death related to MAS occurred in 24 infants (2.5% of the MASINT cohort; 0.96 per 100,000 live births).

CONCLUSIONS

The incidence of MASINT in the developed world is low and seems to be decreasing. Risk of MASINT is significantly greater in the presence of fetal distress and low Apgar score, as well as Pacific Islander and indigenous Australian ethnicity. The increased use of innovative respiratory supports has not altered the duration of mechanical ventilation.

Intrapartum and postdelivery management of infants born to mothers with meconium-stained amniotic fluid: evidence-based recommendations

The article reviews and critically evaluates the available evidence to determine whether the current recommendations for the management of infants born through meconium stained amniotic fluid (MSAF) should be maintained. Authors provide evidence-based recommendations regarding the benefits of amnioinfusion prior to delivery, oral suctioning of the newborn prior to delivery of the shoulder, and the practice of routine endotracheal suctioning of the newborn born through MSAF in preventing meconium aspiration syndrome (MAS). Authors also discuss the gaps in knowledge in all the above interventions to prevent MAS.

Have the year 2000 neonatal resuscitation program guidelines changed the delivery room management or outcome of meconium-stained infants?

OBJECTIVE

To study the impact of neonatal resuscitation program (NRP) guidelines on delivery room (DR) management of infants born through meconium-stained amniotic fluid (MSAF).

STUDY DESIGN

A retrospective study of all term (>or=37 weeks) infants born through MSAF was performed. Patients were divided into two periods: pre year 2000 NRP and post year 2000 NRP. Meconium consistency, APGAR scores and intubation (INT) for suctioning and respiratory outcome were recorded. Groups were analyzed using chi (2) tests and stepwise logistic regression.

RESULTS

The incidence of MSAF remained constant in period 1 (13.6%) and period 2 (13.1%) while the proportion of infants intubated fell from 67 to 41% (p<0.001). The incidence of meconium aspiration and nonspecific respiratory distress did not differ between groups.

CONCLUSIONS

Since the implementation of year 2000 NRP guidelines, the rate of DR INT for tracheal suctioning has fallen significantly without a change in overall respiratory complications. Results of this study support the efficacy of year 2000 NRP recommendations.

Pitfalls in neonatal resuscitation

Ten percent of all newborns require resuscitation at birth. The Neonatal Resuscitation Program establishes the authoritative technique of newborn resuscitation. Errors continue to occur that are related to the use of unskilled resuscitators; intubation; inadequate suctioning of meconium; and the postresuscitation problems of hypoglycemia, hypocarbia, and hypotension. Specific recommendations are offered to avoid these pitfalls of neonatal resuscitation.

Innovative neonatal ventilation and meconium aspiration syndrome

Respiratory failure remains a major cause of morbidity and mortality in the neonatal population. Infants with hypoxemic respiratory failure because of meconium aspiration syndrome (MAS), persistent pulmonary hypertension of the newborn (PPHN), and pneumonia/sepsis have a potential for increased survival with extracorporeal membrane oxygenation (ECMO). Other treatment options previously limited to inotropic support, conventional ventilatory management, respiratory alkalosis, paralysis and intravenousvasodilators have been replaced by high-frequency oscillatory ventilation (HFOV), surfactant, and inhaled nitric oxide (iNO). HFOV has been advocated for use to improve lung inflation while potentially decreasing lung injury through volutrauma. Other reports describe enhanced efficacy of HFOV when combined with iNO. Subsequent to studies reporting surfactant deficiency or inactivation may contribute to neonatal respiratory failure exogenous surfactant therapy has been implemented with apparent success. Recent studies have shown that iNO therapy in the neonate with hypoxemic respiratory failure can result in improved oxygenation and decreased need for ECMO. In this article, the authors place in context of a system-based strategy the prenatal, natal and postnatal management of babies delivered through meconium stained amniotic fluid (MSAF) so that adverse outcomes are minimized, and the least number of babies require innovative ventilatory support. At Pennsylvania Hospital, over a six-year period (1995 to 2000), 14.5% (3370/23,175 of live births babies were delivered with MSAF. These data show that 4.6% (155/3370) of babies with MSAF sustained MAS. Overall, 26% (40/155) of babies with MAS needed ventilatory support (or 0.17% of all live-births); of these only 20% (8/40 or 0.035% of live births) needed innovative ventilatory support. None died or needed ECMO. These data describe the impact of a system-based approach to prevent and manage adverse outcomes related to MSAF at regional Level III perinatal center.

Meconium aspiration produces airway hyperresponsiveness and eosinophilic inflammation in a murine model

Meconium aspiration syndrome is a cause of significant morbidity and mortality in the perinatal period and has been implicated in the pathogenesis of airway dysfunction. In this study, we developed a murine model to evaluate the effects of meconium aspiration on airway physiology and lung cellular responses. Under light anesthesia, BALB/c mice received a single intratracheal instillation of meconium or physiological saline. Respiratory mechanics were measured in unrestrained animals and expressed as percent increase in enhanced pause to increasing concentrations of methacholine (MCh). Furthermore, we assessed the changes in cells and cytokines into the bronchoalveolar lavage fluid (BALF). We found meconium aspiration produced increased airway responsiveness to MCh at 7 days. These functional changes were associated with lymphocytic/eosinophilic inflammation, goblet cell metaplasia, and increased concentrations of IL-5 and IL-13 in the BALF. Our findings suggest meconium aspiration leads to alterations of airway function, lung eosinophilia, goblet cell metaplasia, and cytokine imbalance, thus providing the first evidence of meconium-induced airway dysfunction in a mouse model.

Enhanced release of thromboxane A(2) after exposure of human airway epithelial cells to meconium

Meconium aspiration syndrome (MAS) is a cause of significant morbidity and mortality in the perinatal period. Despite the clinical relevance of MAS, its pathogenesis is poorly understood. Epithelial cell-derived prostanoids are involved in the regulation of several cellular functions within the lung, including the control of tone and reactivity of airway and vascular smooth muscle. In this study, we evaluated whether exposure to meconium affects the metabolic function of human airway epithelial cells. Monolayers of A549 cells, a transformed human epithelial cell line, were incubated with various concentrations of meconium. Control cells were incubated with serum-free medium in a similar manner. The supernatant fluid was removed at various time points and assayed for thromboxane A(2) (TXA(2)) production. The latter was accomplished by measuring its immediate and stable metabolite thromboxane B(2), using an enzyme-linked immunosorbent assay (ELISA). In selected experiments, the modulatory effects of indomethacin (10(-6) M), dexamethasone (10(-6) M), and L-nitroarginine methyl ester (L-NAME, 10(-6) M) on TXA(2) production were evaluated. Results were expressed in terms of pg/mg protein (mean +/- SE). We found that exposure to meconium produced a significant release of TXA(2) from A549 cells. Indomethacin, dexamethasone, and in part, L-NAME inhibited meconium-induced release of TXA(2). Our findings demonstrate that meconium enhances the production of thromboxanes from A549 cells, suggesting that airway epithelial cells and their metabolic products may play an important role in the pathogenesis of MAS.

Delivery room management of the apparently vigorous meconium-stained neonate: results of the multicenter, international collaborative trial

OBJECTIVE

Disagreement exists concerning the appropriate delivery room management of the airway of vigorous meconium-stained infants. Some suggest a universal approach to intubation and suctioning of the airway in all such neonates, whereas others advocate a selective approach. We performed this investigation: 1) to assess whether intubation and suctioning of apparently vigorous, meconium-stained neonates would reduce the incidence of meconium aspiration syndrome (MAS); and 2) to determine the frequency of complications from delivery room intubation and suctioning of such infants.

METHODS

Inclusion criteria included: 1) gestational age >/=37 weeks; 2) birth through meconium-stained amniotic fluid of any consistency; and 3) apparent vigor immediately after birth. Subjects were randomized to be intubated and suctioned (INT) or to expectant management (EXP). Primary outcome measures included: 1) the incidence of respiratory distress, including MAS, and 2) the incidence of complications from intubation.

RESULTS

A total of 2094 neonates were enrolled from 12 participating centers (1051 INT and 1043 EXP). Meconium-stained amniotic fluid consistency was similar in both groups. Of the 149 (7.1%) infants that subsequently demonstrated respiratory distress, 62 (3.0%) had MAS and 87 (4.2%) had findings attributed to other disorders. There were no significant differences between groups in the occurrence of MAS (INT = 3.2%; EXP = 2.7%) or in the development of other respiratory disorders (INT = 3.8%; EXP = 4.5%). Of 1098 successfully intubated infants, 42 (3.8%) had a total of 51 complications of the procedure. In all cases, the complications were mild and transient in nature.

CONCLUSIONS

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.

Effects of dexamethasone on meconium aspiration syndrome in newborn piglets

We examined the effects of dexamethasone on lung function in a piglet model of meconium aspiration syndrome. We induced lung injury in 10 newborn piglets (age 5 +/- 0.2 d) with 4 mL/kg body weight of 20% sterile human meconium in normal saline given via tracheostomy. Ventilator management was aimed at maintaining comparable values of end tidal carbon dioxide, Hb saturation, and arterial blood gases. Lung function was assessed using a BICORE CP100 neonatal monitor. Five piglets received 0.5 mg/kg of dexamethasone 2 and 8 h after meconium administration, whereas control piglets received normal saline at similar times. Ventilator settings, oxygen requirements, and lung compliance were similar between groups at the start of the study. Two hours after the instillation of meconium, there was marked lung dysfunction in both groups as evidenced by increased oxygen requirements [fraction of inspired oxygen (FiO2) 0.98 +/- 0.01 versus FiO2 0.21 +/- 0, p < 0.0001] and reduced lung compliance (0.35 +/- 0.03 versus 0.8 +/- 0.03 mL x kg(-1) x cm(-1) H2O, p < 0.0001). Administration of dexamethasone resulted in lower oxygen requirements (FiO2 0.27 +/- 0.01 versus FiO2 1.0 +/- 0.0, p < 0.00001), lower oxygenation index (2.17 +/- 0.17 versus 22.64 +/- 3.39, p < 0.0001), ventilatory efficiency index (0.30 +/- 0.01 versus 0.07 +/- 0.01, p < 0.0001), and improved lung compliance (0.68 +/- 0.04 versus 0.34 +/- 0.05 mL x kg(-1) x cm(-1) H2O, p < 0.001) compared with the control group. In summary, a two-dose course of 0.5 mg/kg of dexamethasone improved blood gases and lung function in a piglet model of meconium aspiration syndrome.

Meconium aspiration syndrome: current concepts and management

Meconium aspiration syndrome (MAS) is a common neonatal problem with significant morbidity and mortality. This article reviews pathophysiology as well as several current approaches to the management of MAS, including high-frequency ventilation and exogenous surfactant replacement, among others.

Meconium-stained amniotic fluid and the meconium aspiration syndrome. An update

Over the past 5 years, increasing understanding about the pathophysiology of meconium-stained amniotic fluid (MSAF) and the meconium aspiration syndrome (MAS) has occurred. Many new therapies are being used in an attempt to prevent MAS and to treat the disorder. The authors review the current status of knowledge concerning the MSAF and MAS and management of these entities.

Characteristics of successful claims for payment by the Florida Neurologic Injury Compensation Association Fund

OBJECTIVES

Our purpose was to examine the obstetric characteristics of claims paid by the State of Florida after the birth of a neurologically impaired child.

STUDY DESIGN

The Florida Birth Related Neurological Injury Compensation plan is a no-fault alternative to litigation for compensation after a catastrophic neurologic birth injury. The plan has specific criteria for inclusion. We retrospectively analyzed claims for compensation that were accepted and paid (n = 64) after a birth-related neurologic injury. Simple description statistics were compiled for the relative frequencies of various obstetric correlates found in successful claims for payment.

RESULTS

Seventy percent of infants (45) were delivered by cesarean section and 15 of 19 vaginal deliveries (79%) were operative (forceps or vacuum), yielding a 94% operative delivery rate. A persistent nonreassuring fetal heart rate tracing was seen before delivery in all cases. The 5-minute Apgar score was < or = 6 in 91% of deliveries and the 10-minute Apgar score was < 6 in 86% of deliveries. When first examined in the labor and delivery suite, 17 women had a nonreassuring fetal heart rate, and a nonreassuring tracing developed in labor in 47. Nine attempts at vaginal birth after a cesarean section led to a uterine rupture. Seven of these deliveries were either inductions or augmentations against an unfavorable cervix. Forty-five percent (27) of deliveries were associated with meconium-stained amniotic fluid, including 17 infants with meconium aspiration syndrome. There were three shoulder dystocias and four infants with group B streptococcal sepsis. In eight cases (12.5%), there appeared to be a breach of the published standard of care, which contributed to the poor outcome.

CONCLUSION

Most of these cases should not have been eligible for compensation in a traditional tort-based system because the applicable standard of care was not breached. Meeting the published standard for perinatal care failed to prevent these devastating neurologic injuries. Obviously, not all intrapartum injuries can be prevented; however, if we are to prevent similar injuries in the future, we will need to examine the clinical management in these or similar case for clues to develop novel strategies to respond to intrapartum emergencies. An unexpected finding was the frequency of catastrophic birth injuries after an attempted vaginal birth after cesarean section with the predominance of these deliveries associated with oxytocin stimulation against an unripe cervix. It is apparent that the push to lower cesarean section rates is not without some risk.