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PubMed1994

Analysis of monoclonal antibodies reactive with meconium- and amniotic fluid-derived mucin.

The present study was undertaken to determine whether monoclonal antibodies (moABs TKH-2, MA54, MA61, B72.3, and CC49) directed toward O-linked mucin-type glycoprotein detect the NeuAc alpha 2-6GalNAc (sialyl Tn) epitope in meconium- and amniotic fluid-derived mucin. Fetal colonic mucosal cells express the sialyl Tn antigen, particularly in goblet cell mucin. The reactivities of these moABs with a perchloric acid extract of meconium (meconium extract) and different native and neuraminidase treated glycoproteins were examined by solid-phase enzyme-linked immunosorbent assay (ELISA). All the moABs react with the meconium supernatant and meconium extract. The reactivities of TKH-2, MA54, and MA61 are neuraminidase sensitive, and the reactivity of TKH-2 with meconium extract was specifically inhibited by ovine submaxillary mucin (OSM). A NeuAc alpha 2-6GalNAc epitope is the characteristic component in meconium. Mucin released from the fetal respiratory tract could, in part, provide an alternative source in the amniotic fluid. TKH-2 is the most sensitive antibody directed to sialyl Tn antigen in meconium supernatant. The likelihood of TKH-2 serving as the basis for a sensitive assay to detect sialyl Tn in meconium- and amniotic fluid-derived mucin is provided.

Amniotic Fluid↗
PubMed1995

The impact of a policy of amnioinfusion for meconium-stained amniotic fluid.

OBJECTIVE: To evaluate the impact of an amnioinfusion (AI) policy for thick or moderate meconium-stained amniotic fluid (AF) on neonatal outcome, specifically meconium-aspiration syndrome and its complications. METHODS: We reviewed maternal and neonatal charts of 937 vertex, singleton pregnancies complicated by moderate or thick meconium-stained AF during a 3-year period. The patients were divided into groups according to whether AI was performed. Demographic characteristics, risk factors, mode of delivery, pregnancy outcome, and neonatal complications, including meconium-aspiration syndrome, were analyzed. RESULTS: Four hundred forty patients (47%) received AI (AI group); 497 (53%) did not, for the following reasons: imminent delivery (310 patients), occult meconium (141), or emergency cesarean delivery (46) (no-AI group). Our study did not show any reduction in the incidence of 5-minute Apgar scores of 7 or less (8 versus 7%), meconium below the vocal cords (28 versus 29%), meconium aspiration syndrome (4.5 versus 3.8%), ventilation requirement (4.3 versus 2.4%), or neonatal death (0.7 versus 0.2%) in the AI and no-AI groups, respectively. The AI group had a higher incidence of fetal heart rate abnormalities in labor (48 versus 31%, P < .05), instrumental delivery (15 versus 8%, P < .05), cesarean delivery (28 versus 17%, P < .001), and endometritis (21 versus 13%, P = .004). CONCLUSIONS: With the policy of routine AI for moderate or thick meconium-stained AF, AI was not clinically feasible in 53% of the cases. We were unable to demonstrate any improvement in neonatal outcome in those who received AI for moderate or thick meconium.

Adult↗
PubMed1991

Inhibition of pulmonary surfactant function by meconium.

The pathophysiology of meconium aspiration is marked by lung hyperinflation because of airway obstruction, which is often followed by an acute pneumonitis with classic lung injury characteristics. Surfactant dysfunction may contribute to this latter pulmonary pathophysiology. We sought to determine to what extent meconium itself might contribute to a functional surfactant deficiency. Specimens of newborn infants' first meconium were collected and pooled. Serial dilutions of the meconium were then added to various concentrations of calf lung surfactant extract, a mixture with the surface properties of natural surfactant that is used clinically to treat neonatal respiratory distress syndrome, and the dynamic surface activity of these mixtures was studied with a pulsating bubble surfactometer. At surfactant concentrations of less than or equal to 1.5 mg/ml, even 6500-fold dilutions of meconium-inhibited surface tension lowering ability (10 +/- 2 mN/m vs 1 +/- 0.1 mN/m for controls, p less than 0.05). Moreover, this inhibitory activity resided in both the chloroform-soluble and the aqueous phases of meconium and appeared to be additive in nature. However, at sufficiently high concentrations of surfactant, even large amounts of meconium were unable to affect surface tension lowering properties. Thus meconium inhibits surfactant function in a manner that is dependent on the surfactant concentration, suggesting the possible utility of exogenous surfactant therapy in some cases of meconium aspiration.

Animals↗
PubMed1998

Meconium: a marker for peripartum infection.

OBJECTIVE: To test the hypothesis that the presence of meconium-stained amniotic fluid (AF) is associated with maternal and neonatal infection, both before and after delivery. METHODS: Nine hundred thirty-six laboring women were analyzed for the presence of meconium in amniotic fluid and occurrence of peripartum infection. Meconium was assessed clinically as thin, moderate, or thick. Intra-amniotic infection and endometritis were diagnosed by standard definitions. All patients were tested for vaginal group B streptococcus, bacterial vaginosis, and other aerobic organisms. RESULTS: Meconium-stained AF was present in 28% of the study participants (9% thin, 12% moderate, 7% thick). The presence of meconium was associated with increased intra-amniotic fluid (17% versus 9%, relative risk [RRI 1.98, 95% confidence interval [CI] 1.3, 3.1), endometritis (10% versus 5%, RR 2.38, 95% CI 1.3, 4.4), and total infection (25% versus 13%, RR 2.19, 95% CI 1.5, 3.2). Thick meconium had higher infection rates than clear AF (44% versus 13%, RR 5.18, 95% CI 2.9, 9.3). Meconium was associated independently with peripartum infection by multiple logistic regression (RR 1.28, 95% CI 1.1, 1.6). CONCLUSION: Meconium-stained AF is associated with increased peripartum infection, independent of other risk factors for infection. Thick meconium, in particular, is associated with a marked increase in peripartum infectious morbidity.

Adult↗
PubMed2002

The relative risk of 'fetal distress' in pregnancy associated with meconium-stained liquor at different gestation.

Pregnancies complicated with meconium-stained liquor are regarded as at risk of fetal distress. Evidence from animal and human studies indicate that passage of meconium may be related to fetal maturity. This retrospective study attempts to quantify the relative risk of non-reassuring cardiotocography or 'fetal distress' in pregnant women complicated by meconium-stained liquor for preterm, term and post-term pregnancies. A total of 9542 singleton pregnancies, delivered in a tertiary obstetric unit in Hong Kong between 1 July 1996 and 31 June 1999, were included in the study. Of these pregnancies, 1946 (20.4%) were identified as having meconium-stained liquor, ranging from thin to thick staining. There was a strong association between incidence of meconium-stained liquor (P < 0.0005) and moderate/thick meconium-stained liquor with advanced gestational age. The incidence of non-reassuring cardiotocography in women presenting with meconium-stained liquor was significantly higher (9.8% vs. 6.4%). The relative risk of non-reassuring cardiotocography in women with meconium-stained liquor increased with more advanced gestation. Close fetal surveillance during labour is required among these pregnancies. Premature labour is associated with higher incidence of fetal distress but the presence of meconium did not pose an additional risk.

Amniotic Fluid↗
PubMed2002

The effect of meconium on perinatal outcome: a prospective analysis.

OBJECTIVE: To evaluate the effect of meconium-stained amniotic fluid (AF) on perinatal outcome. METHODS: A prospective observational study was performed, comparing perinatal outcome of parturients with thick and thin meconium-stained AF to those with clear AF. RESULTS: The rate of meconium-stained AF was 18.1% (106/586). Of those, 78 (13.3%) patients had thin and 28 (4.8%) had thick meconium-stained AF. The rate of oligohydramnios was significantly higher among pregnancies complicated with thick meconium-stained AF (OR 7.2, 95% Cl 2.1-24.1; p = 0.002). A significant linear association, using the Mantel-Haenszel test for linearity, was found between the thickness of the meconium and abnormal fetal heart rate patterns during the first and second stages of labor, low Apgar scores at 1 min and the risk for Cesarean section. A statistically significantly higher risk for neonatal intensive care unit admission was observed among patients with thick meconium as compared to those with clear AF (OR 11.4, 95% CI 2.0-59.3; p = 0.006), even after adjustment for oligohydramnios and abnormal fetal heart rate patterns. CONCLUSIONS: Thick, and not thin, meconium-stained AF, was associated with an increased risk for perinatal complications during labor and delivery. Therefore, thick meconium-stained AF should be considered a marker for possible fetal compromise, and lead to careful evaluation of fetal well-being.

Adult↗
PubMed1996

Cocaine disposition in meconium from newborns of cocaine-abusing mothers and urine of adult drug users.

The analysis of meconium for cocaine and metabolites has proved to be a reliable method for the detection of fetal cocaine exposure. Better sensitivity and a larger gestational window of detection have been demonstrated for meconium testing as compared with neonatal urine testing. Cocaine and cocaine metabolites, including benzoylecgonine, ecgonine methyl ester, cocaethylene, norcocaine, benzoylnorecgonine, and m-hydroxybenzoylecgonine, have been identified in meconium. The origin of these metabolites, whether maternal or fetal, has not been established. This study was conducted to compare the disposition of cocaine and metabolites in meconium from fetuses exposed to cocaine with that of urine from cocaine abusers. Meconium specimens were obtained from six neonates of mothers positive for cocaine use by urinalysis or self-reporting or both during pregnancy. Urine specimens were obtained from 17 adult female and 17 adult male cocaine users enrolled in a treatment program. Specimens were analyzed by gas chromatography-mass spectrometry for cocaine and 12 related analytes. The following analytes were identified and measured in meconium and urine: anhydroecgonine methyl ester; ecgonine methyl ester; ecgonine ethyl ester; cocaine; cocaethylene; benzoylecgonine; norcocaine; norcocaethylene; benzoylnorecgonine; m-and p-hydroxycocaine; and m-and p-hydroxybenzoylecgonine. In addition, both m-and p-hydroxybenzoylecgonine were found to exhibit approximately equal cross-reactivity with benzoylecgonine in the EMIT and TDx assays. The presence of p-hydroxybenzoylecgonine in meconium suggested that this newly identified metabolite, like m-hydroxybenzoylecgonine, might serve as a valuable marker of fetal cocaine exposure during pregnancy. The presence of cocaine and anhydroecgonine methyl ester in meconium was attributed to transfer across the placenta from the mother. However, the origin of the hydrolytic and oxidative metabolites of cocaine could not be established because they were also identified in urine specimens of adult female cocaine users and could have arisen in meconium from either fetal or maternal metabolism.

Adult↗
PubMed1996

Risk factors for meconium-aspiration syndrome.

The aim of this retrospective study was to identify risk factors for meconium-aspiration syndrome, and to identify antenatal and intrapartum risk factors which might be preventable. We analyzed maternal and neonatal records of the 210 infants who had meconium-stained liquor and who also developed respiratory distress necessitating admission to the Special Care of Intensive Care Baby Units at National Women's Hospital, Auckland in 1992. Meconium-aspiration syndrome occurred in 6.6% of meconium exposed babies and in 1.3% of total births. Severe meconium-aspiration syndrome developed in 18 infants, moderate in 48, mild in 60 respiratory distress in 84. An association was found between meconium aspiration syndrome and primiparity (p = 0.001) and Pacific Island ethnicity (p = 0.0002). An association was also found between the severity of meconium and low umbilical artery pH (p = 0.0002). Thick meconium and an abnormal cardiotocograph were more common in severe meconium-aspiration syndrome. All deaths and long-term morbidity occurred in babies with abnormal cardiotocographs or in unmonitored infants. Preventable antenatal and intrapartum factors were not identified in this study.

Adult↗
PubMed2006

Alpha-1-antitrypsin and IgA in serial meconium and faeces of healthy breast-fed newborns.

BACKGROUND: Meconium is a series of layers formed in the foetal intestine from the 12th week of gestation. High content of meconial alpha-1-antitrypsin (AAT), decreasing within the first several days of extrauterine life appears to reflect the meconium clearance of the gut. At birth, IgA is not present in the meconium and breast-fed infants receive this antibody postnatally with human milk. The aim of the study was to determine changes in AAT concentrations, functional activity of that inhibitor expressed as trypsin inhibitory capacity (TIC) and IgA concentration in serial meconium and faeces, as endogenous biochemical markers discriminating between faeces portions formed in intrauterine and extrauterine life periods of healthy breast-fed newborns. METHODS: A group of 24 healthy breast-fed newborns delivered by spontaneous labour were studied prospectively during the first 4 days of postnatal life. AAT and IgA concentrations in the newborn's meconial and faecal samples and IgA concentration in mother's milk samples taken on the third day after delivery, were determined by radial immunodiffusion. TIC was assessed using BAPNA (N-benzoyl-DL-arginine-p-nitroanilide). RESULTS: The medians (range) of AAT concentrations in milligrams per gram of dry meconium or faeces were: 68.8(29.2-138.4) (day 1), 56.9 (30.8-112.8) (day 2), 26.2 (6.8-80.7) (day 3), and 6.6 (1.4-27.1) (day 4). The medians (range) of TIC in milligrams of trypsin/g dry mass of meconium or faeces were: 0.76 (0.33-1.79) (day 1), 0.44 (0.17-1.08) (day 2), 0.16 (0.03-0.56) (day 3), and 0.03 (0-0.11) (day 4). The median (range) of IgA concentration in mothers' milk was 715 mg/dl (420-890). IgA was absent in meconium portions from the first day of life while on the successive days the medians (range) of IgA concentration in mg/g dry mass of meconium and faeces were as follows: 0 (0-2.90) (day 2), 2.50 (1.10-9.60) (day 3), 7.05 (4.10-30.60) (day 4). On day 4 of extrauterine life a negative correlation was found between AAT and IgA concentrations in faeces of the newborns (r = -0.46) and a positive correlation was seen between IgA concentrations in faeces and milk (r = 0.93). CONCLUSIONS: Analyses of the systematic decrease in AAT and increase of IgA concentration in serial portions of meconium and faeces over the first days of extrauterine life of breast-fed newborns can date newborn's faeces portions formed during intrauterine and extrauterine maturation. AAT deposited in foetal intestine is an active antiprotease.

Analysis of Variance↗
PubMed1995

In vitro model of human umbilical venous perfusion to study the effects of meconium staining of the umbilical cord.

Because meconium diffuses into placental and umbilical cord tissue, its bioactive components are potentially capable of entering the fetal circulation. Meconium diluted in Krebs solution produces vasoconstriction in human umbilical vein segments that are suspended in a milieu similar to that of the amniotic cavity. Based on published observations, we wanted to determine if very diluted meconium could induce vasospasm in intact umbilical cords. Human umbilical cords were obtained from full-term deliveries, cut into 2 equal segments, cannulated, and perfused continuously as test and control cords. The study included four parts: (1) intraluminal meconium (n = 6; 0.01-1% solution); (2) 4-hour exposure to 10% meconium-stained amniotic fluid of intact umbilical cords (n = 8); (3) 4-hour exposure to a 10% meconium-stained amniotic fluid of umbilical cords denuded of their epithelial layer (n = 5); (4) 24-hour exposure to a 10% meconium-stained amniotic fluid of intact umbilical cords (n = 9). Significant vasoconstriction of the umbilical vein occurred only with the intraluminal meconium solution exposure (p = 0.034). In this in vitro model meconium staining of the umbilical cord was not associated with vasoconstriction of the umbilical vein.

Humans↗
PubMed2006

Morphological alterations of exogenous surfactant inhibited by meconium can be prevented by dextran.

BACKGROUND: Surfactant dysfunction due to inhibition is involved in the pathophysiology of meconium aspiration syndrome. Dextran addition has been shown to reverse exogenous surfactant inactivation by meconium, but the precise mechanisms and the morphological correlate of this effect are yet unknown. Morphological surfactant analysis by transmission electron microscopy (TEM) and stereology allows the differentiation of active (large aggregates = LA) and inactive (small aggregates = SA) subtypes. METHODS: To determine the in vitro effects of meconium and dextran addition on the morphology of a modified porcine natural surfactant (Curosurf), Curosurf samples were either incubated alone or together with meconium or with meconium and dextran, fixed and processed for TEM. Volume fractions of surfactant subtypes [lamellar body-like forms (LBL), multilamellar vesicles (MV), unilamellar vesicles (UV)] were determined stereologically. RESULTS: All preparations contained LBL and MV (corresponding to LA) as well as UV (corresponding to SA). The volume fraction of UV increased with addition of meconium and decreased with further addition of dextran. Correspondingly, the UV/(LBL+MV) ratio (resembling the SA/LA ratio) increased when meconium was added and decreased when dextran was added to the surfactant-meconium mixture. CONCLUSION: Meconium causes alterations in the ultrastructural composition of Curosurf that can be visualized and analyzed by TEM and stereology. These alterations resemble an increase in the SA/LA ratio and are paralleled by an increase in minimum surface tension. Dextran prevents these effects and may therefore be a useful additive to exogenous surfactant preparations to preserve their structural and functional integrity, thereby improving their resistance to inactivation.

Biological Products↗
PubMed2001

Dexamethasone treatment attenuates pulmonary injury in piglet meconium aspiration.

To investigate the pulmonary effects of steroid treatment in neonates with meconium aspiration, 25 10- to 12-d-old piglets were studied for 6 h after an intratracheal bolus of human meconium. Dexamethasone (0.5 mg/kg) was given in two treatment schedules, either 1 h before (n = 6) or 1 h after meconium instillation (n = 8). Eight piglets served as controls. Three additional piglets were given dexamethasone without meconium instillation. Pulmonary hemodynamics and oxygenation were followed, and lung tissue samples investigated for signs of inflammation and ultrastructural injury, including apoptosis. Pulmonary artery pressure and vascular resistance increased after meconium instillation, but this rise was significantly prevented after prophylactic dexamethasone. This treatment also improved the acutely deteriorated oxygenation of the piglets after meconium insufflation. Prophylactic, but not early, dexamethasone treatment further protected the lungs from the ultrastructural changes caused by meconium instillation. Additionally, the increase of apoptotic epithelial cell deaths was significantly prevented by both dexamethasone treatments. These results show that prophylactic dexamethasone treatment significantly attenuates the early pulmonary hemodynamic deterioration and structural lung damage caused by meconium aspiration. Further studies on the apoptosis-inhibiting effect of dexamethasone administration in neonatal lungs exposed to heavy meconium are warranted.

Animals↗
PubMed2002

Microscopic changes induced by the intratracheal inoculation of amniotic fluid and meconium in the lung of neonatal rats.

Meconium aspiration syndrome is a major contributor to neonatal respiratory distress in infants and it has been sporadically recognized in neonatal animals. This investigation was designed to study the short and long term effects of meconium and amniotic fluid in the lungs of neonatal rats. Seven-day-old rats (n = 123) divided in three groups were intratracheally inoculated with saline solution, amniotic fluid or meconium. Rats were euthanatized on 1, 3, 7, 14, 28, 56 and 112 postinoculation days (PID) and the lungs were examined by light microscopy. Saline solution did not induce any change while amniotic fluid elicited only a mild foreign body response which disappeared by PID 14. In contrast, meconium induced an exudative alveolitis characterized by recruitment of neutrophilsn in the bronchoalveolar spaces. Meconium also induced atelectasis, hyperinflation and thickening of alveolar septa all of which had disappeared by PID 14. Starting at PID 7, neutrophils were progressively replaced by macrophages, giant cells, and some fibroblasts. There were sporadic foci of mineralization starting at PID 14 and lasting up to PID 112. Some mineralized foci became lined with cuboidal epithelial cells at PID 28. Meconium was slowly degraded but still evident by PID 112. It was concluded that inoculation of meconium in neonatal rats induces acute microscopic changes typical of meconium aspiration syndrome. The long term lesions induced by meconium consisted of persistent multifocal histiocytic alveolitis and bronchiolitis reaction with occasional foci of calcification.

Amniotic Fluid↗
PubMed2001

Meconium concentration and amniotic fluid index influence the outcome of amnioinfusion.

BACKGROUND: To determine the usefulness of amnioinfusion as a function of meconium concentration and amniotic fluid index. METHODS: This was a prospective study of 206 pregnant women in whom amniotic fluid was moderately or heavily stained with meconium, according to subjective evaluation. The women were assigned randomly to receive amnioinfusion (n=103) or no amnioinfusion (control group, n=103). The results were compared in women with =/<15 % or >15 % meconium in the amniotic fluid (measured by centrifugation), and in women in whom the amniotic fluid index calculated 60 min after insertion of the amnioinfusion catheter was <10 or =/>10. RESULTS: In women with >15% meconium, amnioinfusion decreased the rate of cesarian sections motivated by fetal distress (2.5% vs 22.2%), and in women with =/<15% meconium, amnioinfusion decreased the presence of meconium below the vocal cords (6.4% vs 25.9%). Greater benefits after amnioinfusion were seen in women with an amniotic fluid index =/>10: the rate of cesarian sections was lower (1.3% vs 13.3%), as was the frequency of meconium below the vocal cords (10.1% vs 33.3%). CONCLUSIONS: Beneficial effects of amnioinfusion were seen in women with high and low concentrations of meconium, and with high and low amniotic fluid indexes. These criteria should therefore not be used to decide whether amnioinfusion is indicated when the amniotic fluid is moderately or heavily stained with meconium.

Adult↗
PubMed1988

Failure to prevent meconium aspiration syndrome.

To determine the impact of routine naso-oropharyngeal DeLee and tracheal suction on the prevention of meconium aspiration syndrome, we compared 755 infants with meconium-stained fluid, born during a 12-month period (1983), with a similar group of 742 infants born in a previous year (1975) when these suctioning techniques were not routinely used. Morbidity and mortality data from meconium aspiration syndrome in 103 infants, using combined DeLee and tracheal suction during a five-year period (1979-1983), were also analyzed retrospectively. In spite of a combined DeLee and tracheal approach toward the prevention of meconium aspiration, the rate of meconium aspiration syndrome (2%) was not different in 1975 and 1983. Timing of obstetric DeLee suction (whether before or after delivery of the chest) did not influence the presence of meconium below the vocal cords (37 versus 36%, respectively). Even though significant morbidity remained associated with meconium aspiration in both periods studied, a drastic reduction occurred in neonatal mortality, from 46%, in 1975 to 12.5% in 1983, which was probably aided by major advances in perinatal care and supports routine prophylactic suctioning of meconium at birth. From these findings, we suggest that meconium aspiration syndrome is predominantly an intrauterine event secondary to fetal distress, and that DeLee and tracheal suctioning reduce only its severity.

Asphyxia Neonatorum↗
PubMed1985

[Studies on meconium-like substances in the urine of mother and neonate during perinatal period].

It is well known that the entry of amniotic fluid into the mother's circulation may result in the occurrence of amniotic embolism, and aspiration of meconium by the neonate may cause meconium aspiration syndrome. To study meconium-like substances detected in the urine of mother and neonate during the perinatal period, the authors carefully assayed the Urinary Meconial Index (UMI) in subjects including 100 pregnant women, 171 parturient women, 171 neonates and 68 samples of amniotic fluid. Through the UMI assay, the frequency of the appearance of high UMI, the mode of delivery at high UMI and its effect upon both mother and neonate were studied and the following findings obtained. The entry of meconium into the mother's circulation occurs during labor pains and may be excreted into the mother's urine (6.4%). Labor pains enhance the entry of meconium into the mother's circulation and the entry takes place even in the absence of any clinical signs of rupture of the membranes (p less than 0.01). The entry of meconium into both mother and neonate occurs at a higher rate in dystocia and in cases with meconium-stained amniotic fluid (p less than 0.05). Even in the absence of marked symptoms such as those in meconium aspiration syndrome, the aspiration of meconium affects postnatal course of the newborn (positive CRP, early appearance of bilirubinemia: p less than 0.05).

Amniotic Fluid↗
PubMed2001

The use of intratracheal pulmonary ventilation and partial liquid ventilation in newborn piglets with meconium aspiration syndrome.

OBJECTIVE: To determine whether intratracheal pulmonary ventilation (ITPV) combined with partial liquid ventilation (PLV) improves oxygenation and ventilation at lower mean airway and peak inspiratory pressures when compared with conventional mechanical ventilation in a piglet model of meconium aspiration syndrome. DESIGN: Prospective, randomized, interventional study. SETTING: Animal Research Laboratory at the Children's National Medical Center, Washington, DC. SUBJECTS: Twenty newborn piglets, 1 to 2 wks of age, 1.8-2.8 kg in weight. INTERVENTION: The animals were anesthetized, paralyzed, and intubated with a 4.0 mm (internal diameter) endotracheal tube via a tracheostomy and were ventilated. Catheters were placed in the femoral artery and vein. Seven milliliters per kilogram of 20% human meconium was insufflated into the lungs over 30 mins. Dynamic pulmonary compliance was measured before and after instillation of meconium. Animals were ventilated to maintain arterial blood gases in a normal range, that is, pH = 7.35-7.45, Paco(2) = 40-45 torr (5.3-6.0 kPa), and Pao(2) = 70-90 torr (9.3-12.0 kPa). Ventilator settings were increased as needed to a maximum setting of Fio(2) = 1.0, peak inspiratory pressure (PIP) = 40 cm H(2)O, positive end-expiratory pressure = 5 cm H(2)O, and intermittent mandatory ventilation = 60 bpm. After a period of stabilization, 30 mL/kg of perflubron (Liquivent; Alliance Pharmaceutical Corp., San Diego, CA) was given intratracheally over 30 mins and the animals were randomized to either ITPV or control group. Measurements and RESULTS: Arterial blood gases were taken every 30 mins, and ventilatory settings were adjusted to achieve the targeted blood gas parameters. The animals' temperature, arterial blood pressure, heart rate, and oxygen saturation were monitored continuously. There was a significant decrease in the dynamic pulmonary compliance measurements in both groups immediately after meconium instillation. Compliance measurements after meconium instillation were similar in both groups (0.67 +/- 0.23 mL/cm H(2)O/kg ITPV; 0.88 +/- 0.46 mL/cm H(2)O/kg conventional, p =.17), indicating a similar degree of injury before the administration of perflubron. PIP and mean airway pressures were not significantly different at baseline; however, there was significant difference in PIP at 0, 2, and 4 hrs after administration of perflubron (p <.05). The maximum PIP and mean airway pressure were seen in both groups after meconium instillation before perflubron administration, with a mean PIP of 29.0 +/- 4.6 cm H(2)O in ITPV and 28.8 +/- 2.1 cm H(2)O in control. Mean airway pressure was significantly different between the two groups at 0, 1, 2, 3, and 4 hrs after perflubron administration. Lung pathology showed a uniform distribution of meconium in animals of both groups. The alveolar spaces were relatively clear of meconium and appeared to be well preserved. CONCLUSION: The results of this study indicate that ITPV combined with PLV allows for effective ventilation and oxygenation in piglets with meconium aspiration syndrome at lower mean airway pressure and PIP compared with conventional ventilation combined with PLV.

Journal Article↗
PubMed1994

Prophylactic amnioinfusion in pregnancies complicated by thick meconium.

OBJECTIVE: We hypothesized that prophylactic intrapartum amnioinfusion in pregnancies complicated by thick meconium will not decrease the incidence of fetal distress, cesarean section for fetal distress, or meconium below the cords. STUDY DESIGN: Patients with thick meconium were randomized to amnioinfusion (n = 65) or control (n = 59). The amnioinfusion group received an 800 ml bolus of normal saline solution followed by a continuous infusion at 180 ml/hr. Continuous variables were compared by Student t test, and discrete variables were compared by chi 2 analysis and Fisher's exact test as appropriate. RESULTS: The incidence of fetal distress (16 of 65 vs 8 of 59) and cesarean section for fetal distress (seven of 65 vs seven of 59) was not significantly different between the amnioinfusion and control groups, respectively. The rate of meconium below the cords (one of 65 vs eight of 59) was significantly lower in patients receiving amnioinfusion (relative risk 0.09, confidence interval 0.01 and 0.82, p = 0.02). Two cases of meconium aspiration syndrome occurred in control patients but in none receiving amnioinfusion (p = 0.22). CONCLUSION: Prophylactic amnioinfusion in patients with thick meconium decreases the incidence of meconium below the cords and may subsequently have an impact on the incidence of meconium aspiration syndrome in larger series.

Adolescent↗