morphine and Pneumonia--Aspiration

Discussed in this article are the three main anatomic types of persistent pulmonary hypertension of the newborn; (1) maladaptation of the pulmonary vascular bed; (2) excessive muscularization of the pulmonary vascular bed; and (3) underdevelopment of the pulmonary vascular bed.

Topics: Amniotic Fluid; Animals; Arteries; Diagnosis, Differential; Heart Defects, Congenital; Heart Septal Defects, Ventricular; Hernia, Diaphragmatic; Hernias, Diaphragmatic, Congenital; Humans; Hypertension, Pulmonary; Infant, Newborn; Kidney; Lung; Meconium; Persistent Fetal Circulation Syndrome; Pneumonia, Aspiration; Prognosis; Pulmonary Alveoli; Pulmonary Circulation; Rabbits; Rats; Sheep; Vascular Resistance; Vasoconstriction

Topics: Asphyxia Neonatorum; Blood Viscosity; Female; Fetal Growth Retardation; Humans; Hyperglycemia; Hypocalcemia; Hypoglycemia; Infant, Newborn; Infant, Newborn, Diseases; Meconium; Patient Care Team; Pneumonia, Aspiration; Pregnancy; Prognosis

Topics: Acid-Base Equilibrium; Acidosis; Asphyxia Neonatorum; Blood Circulation; Blood Glucose; Body Temperature Regulation; Calcium; Central Nervous System Diseases; Humans; Hyaline Membrane Disease; Hypoxia; Infant, Newborn; Meconium; Oxygen Consumption; Pneumonia, Aspiration

The frequency of complications and fetal macrosomia occurring in 243 patients with excellent dates indicating that their pregnancy was prolonged beyond 40 weeks (280 days) was analyzed and compared with that from a control group of 250 normal patients whose pregnancy ended spontaneously between 38 and 40 weeks of gestation. Complications (intrapartum fetal distress, traumatic deliveries, meconium aspiration, postmaturity syndrome) were significantly more frequent in patients in the study group (25.1%) than in the controls (5.6%). Similarly, fetal macrosomia occurred significantly more often in the study patients (29.6%) than in the controls (10.4%). To study the efficacy of antepartum surveillance in predicting these abnormal events, the postterm patients were randomized between two plans of management: 126 were followed with weekly nonstress testing (NST), and 117 with NST plus weekly ultrasound evaluation of fetal size, amniotic fluid volume, and placental grade. Contraction stress testing (CST) was used if the NST was nonreactive. Electronic monitoring had positive and negative predictive values of 42.8 and 87.7%, respectively, whereas ultrasound-plus-electronic monitoring had values of 50 and 65.3%, respectively. These results indicate that the increased incidence of complications in pregnancy prolonged beyond 40 weeks cannot be adequately predicted with antepartum electronic monitoring and ultrasound evaluation of fetal size, placental grade, and amniotic fluid volume.

Topics: Adult; Female; Fetal Distress; Fetal Macrosomia; Fetal Monitoring; Humans; Meconium; Pneumonia, Aspiration; Pregnancy; Pregnancy, Prolonged; Probability; Prospective Studies; Random Allocation; Ultrasonography

A prospective controlled randomized study of the use of extracorporeal membrane oxygenation to treat newborns with respiratory failure was carried out using the "randomized play-the-winner" statistical method. In this method the chance of randomly assigning an infant to one treatment or the other is influenced by the outcome of treatment of each patient in the study. If one treatment is more successful, more patients are randomly assigned to that treatment. A group of 12 infants with birth weight greater than 2 kg met objective criteria for high mortality risk. One patient was randomly assigned to conventional treatment (that patient died); 11 patients were randomly chosen for extracorporeal membrane oxygenation (all survived). Intracerebral hemorrhage occurred in one of 11 surviving children. Extracorporeal membrane oxygenation allows lung rest and improves survival compared to conventional ventilator therapy in newborn infants with severe respiratory failure.

Topics: Birth Weight; Clinical Trials as Topic; Extracorporeal Circulation; Follow-Up Studies; Hernia, Diaphragmatic; Hernias, Diaphragmatic, Congenital; Humans; Infant, Newborn; Meconium; Oxygenators, Membrane; Persistent Fetal Circulation Syndrome; Pneumonia, Aspiration; Prospective Studies; Pulmonary Veins; Random Allocation; Respiratory Distress Syndrome, Newborn; Respiratory Insufficiency

To evaluate the efficacy of glucocorticoids in the treatment of infants with meconium aspiration syndrome, a double-blind study using hydrocortisone or a lactose placebo was undertaken. Thirty-five infants were included in the study. No significant differences in arterial Po2, Pco2, pH, A-aDo2 gradients, in requirement for assisted ventilation, or in survival were domonstrated between the groups. In control infants, a significant decrease (p less than 0.01) in respiratory distress score was found at 48 to 72 hours of age; in treated infants, it was seen only after 72 hours. The infants in the treated group took a significantly longer (p less than 0.01) period of time to wean to room air than those in the control group (68.9 +/- 9.6 hours vs 36.6 +/- 6.9 hours). On the basis of these observations, hydrocortisone is not recommended for treatment of MAS.

Topics: Drug Evaluation; Humans; Hydrocortisone; Infant, Newborn; Meconium; Placebos; Pneumonia, Aspiration; Respiratory Distress Syndrome, Newborn

Topics: Animals; Animals, Newborn; Disease Models, Animal; Meconium; Pneumonia, Aspiration; Swine

To evaluate effects of inhaled nitric oxide (iNO) on the expression of lung neutrophil adhesion molecule CD(11b) in experimental meconium aspiration pneumonia treated with conventional mechanical ventilation under room air or 100% O(2).. Rabbits were randomly allocated to 10 groups (n = 60), 6 of each group. Control or meconium aspiration pneumonia model groups were inhaled with room air or 100% O(2). Six treatment groups were treated with continuous NO inhalation at the doses of 6 x 10(-6), 10 x 10(-6) and 20 x 10(-6), respectively for 12 hours under room air or 100% O(2). The ratio of wet/dry (W/D) lung weight, alveolar septal width (ASW), myeloperoxidase (MPO) activity and lung injury score were measured. The expression of CD(11b) in neutrophils of the bronchoalveolar lavage fluid (BALF) was detected with flow cytometry.. After 12 hours ventilation, the oxygenation was maintained better in treatment groups under different O(2) concentrations than that in model groups. Inflammatory evidence was found in lungs from all the model groups and treatment groups, which was characterized by serious inflammatory cell infiltration in alveolar space and hyaline membrane formation. The lung inflammation was decreased in all groups with nitric oxide inhalation. The ratio of W/D lung weight and ASW among different groups had no significant difference. MPO activities were significantly decreased in groups treated with 10 x 10(-6) and 20 x 10(-6) iNO compared with the model groups [with the concentration of 21% O(2), (1.8 +/- 0.2) U/g vs (4.4 +/- 0.5) U/g and (2.0 +/- 0.1) U/g vs (4.4 +/- 0.5) U/g;with the concentration of 100% O(2), (1.7 +/- 0.4) U/g vs (2.8 +/- 0.5) U/g and (1.4 +/- 0.3) U/g vs (2.8 +/- 0.5) U/g, P < 0.05, respectively]. MPO activities in the 20 x 10(-6) iNO group under 100% O(2) were significantly reduced compared with those under 21%O(2) [(1.4 +/- 0.3) U/g vs (2.0 +/- 0.1) U/g, P < 0.05]. Nitric oxide inhalation with the doses of 10 x 10(-6) and 20 x 10(-6) significantly decreased the expression of CD(11b) (MFI) in neutrophils of the BALF compared with the expressions in model groups without NO treatment (with 21% O(2), 121 +/- 20 vs 392 +/- 204 and 112 +/- 30 vs 392 +/- 204; with 100% O(2), 113 +/- 24 vs 293 +/- 65 and 102 +/- 14 vs 293 +/- 65, P < 0.05, respectively). Under the same iNO dose (10 x 10(-6) or 20 x 10(-6)) no statistic difference was found between groups of different inspired oxygen concentrations (21% and 100%).. Inhaled nitric oxide with the doses of 10 x 10(-6) to 20 x 10(-6) could significantly down-regulate the CD(11b) expression in neutrophil of the BALF and reduce the neutrophil sequestration and MPO activity in rabbit lungs, which may decrease the lung inflammation process in meconium aspiration pneumonia.

Topics: Administration, Inhalation; Animals; CD11b Antigen; Disease Models, Animal; Female; Flow Cytometry; Lung; Male; Meconium; Neutrophils; Nitric Oxide; Peroxidase; Pneumonia, Aspiration; Rabbits; Random Allocation

A total of 3472 deliveries were studied over a year to evaluate (i) the importance of thin meconium stained liquor (MSL) in the causation of meconium aspiration syndrome (MAS), and (ii) the efficacy of intrapartum plus endotracheal suction at birth in the prevention of MAS due to thin meconium. Two hundred and ninety four (8.5%) of deliveries had meconium stained liquor of which thin MSL was present in 101. MAS occurred in 98 babies. Thin MSL was responsible for 19.4% of cases of MAS. Inspite of intrapartum suction, a high proportion (55-78%) of infants had meconium in the trachea, though thin meconium was found in the trachea significantly less often than thick meconium. Combined intrapartum and endotracheal suction reduced the incidence of MAS due to thin meconium from 26% to 16%. MAS due to thin meconium occurred in asphyxiated as well as vigorous babies inspite of combined suction. Thin meconium accounts for a significant proportion of deliveries with MSL and causes a considerable number of cases of MAS. To prevent meconium aspiration syndrome caused by thin meconium, all neonates born through thin MSL, whether they are asphyxiated or not should undergo intrapartum suction followed by immediate endotracheal suction at birth.

Topics: Asphyxia Neonatorum; Delivery, Obstetric; Female; Humans; Incidence; Infant Care; Infant, Newborn; Meconium; Meconium Aspiration Syndrome; Mouth; Nasopharynx; Pneumonia, Aspiration; Pregnancy; Prospective Studies; Respiratory Distress Syndrome, Newborn; Suction; Trachea

We report the successful treatment with extracorporeal membrane oxygenation of two Dutch neonates with severe respiratory insufficiency, due to meconium aspiration syndrome and persistent fetal circulation respectively. During this procedure part of the cardiac output is led outside the body via a venous cannula in the right atrium, oxygenated in a membrane oxygenator, rewarmed to the patient's body temperature in a heat exchanger and returned to the patient via a cannula in the carotid artery debouching into the aortic arch.

Topics: Extracorporeal Membrane Oxygenation; Female; Humans; Infant, Newborn; Male; Meconium; Persistent Fetal Circulation Syndrome; Pneumonia, Aspiration; Respiration, Artificial; Respiratory Insufficiency

Plasma concentrations of immunoreactive human atrial natriuretic peptide (human ANP) were sequentially determined in 12 infants with respiratory distress syndrome (RDS) or meconium aspiration syndrome (MAS) during various phases of diuresis to elucidate the role of human ANP in the occurrence of spontaneous diuresis in the newborn. Plasma immunoreactive ANP concentrations during the diuretic as well as the maximum diuretic phase were significantly (p less than 0.001) higher than during the prediuretic phase. A gradual decrease occurred during the post diuretic phase, returning to prediuretic values after one week of life. Significant natriuresis, increased glomerular filtration rate, mild hyponatremia, and decreased blood pressure were observed in the diuretic phase in all the cases studied. These results suggest that hypersecretion of human ANP may play an important part in initiating spontaneous diuresis in sick neonates.

Topics: Atrial Natriuretic Factor; Diuresis; Female; Humans; Infant, Newborn; Kidney; Male; Meconium; Pneumonia, Aspiration; Respiratory Distress Syndrome, Newborn; Syndrome; Urine

Meconium aspiration occurred in 66 of 120 infants with meconium-stained liquor admitted to a Neonatal Unit. Four of the 66 infants died, whilst 17 other required ventilatory support. Meconium aspiration syndrome, especially when severe, was more likely if the mother was a smoker, hypertensive, anaemic, Maori or the pregnancy was greater than 42 weeks' gestation. Meconium aspiration was also associated with thick meconium, prolonged labour, late fetal heart decelerations and inadequate suctioning of the airway at birth. Although meconium-stained liquor is a common occurrence in labour, a bad neonatal outcome will only be obviated by vigilant intrapartum care and active suctioning of the infant's airway at birth. Once aspiration has occurred, intensive treatment is often required and sometimes fails.

Topics: Ethnicity; Female; Gestational Age; Heart Rate, Fetal; Humans; Infant, Newborn; Labor, Obstetric; Meconium; New Zealand; Pneumonia, Aspiration; Pregnancy; Retrospective Studies; Risk; Smoking; Time Factors

Meconium, an ether extract of meconium, and the major free fatty acids of meconium (palmitic, stearic, and oleic acids) were all found to increase the surface tension minimum of dog lung extract in a Wilhelmy balance. Each of these fractions was instilled into the lungs of dogs (15 experimental, eight saline solution controls), and cardiac output, venous and arterial blood gases, pulmonary, atrial, and systemic pressures, airway pressure, and static lung compliance were serially monitored for 2 hours. Mean airway pressure increased and static lung compliance decreased significantly in all of the experimental groups. Although arterial pH and PaCO2 and the various hemodynamic measurements did not change during the experiment, PaO2 decreased significantly and did not return to baseline in all experimental groups. Extracts from atelectatic portions of experimental dog lung had a surface tension minimum of greater than 20 dynes/cm, whereas airway foam had a surface tension minimum of less than 10 dynes/cm, suggesting that the free fatty acids of meconium are able to strip surfactant from the alveoli.

Topics: Animals; Dogs; Fatty Acids, Nonesterified; Humans; Infant, Newborn; Meconium; Pneumonia, Aspiration; Pulmonary Atelectasis; Pulmonary Surfactants; Surface Tension

Topics: Female; Humans; Infant, Newborn; Meconium; Pneumonia, Aspiration; Pregnancy; Syndrome

The nonstress test (NST) remains in widespread use for antepartum fetal surveillance. Our institutional experience with 14,028 patients and 38,645 tests over eight years reveals a fetal death rate of 2.6 per 1000 within seven days of a reactive NST. The autopsy findings of 53 fetal deaths are presented. The most common findings, in descending order of frequency, were meconium aspiration, perinatal infection, and abnormal umbilical cord position. These findings support changes we have made in our antepartum assessment protocols.

Topics: Female; Fetal Death; Fetal Diseases; Fetal Monitoring; Heart Rate, Fetal; Humans; Infant, Newborn, Diseases; Infections; Meconium; Pneumonia, Aspiration; Pregnancy; Umbilical Cord

This report describes a term gestation abdominal pregnancy resulting in meconium aspiration syndrome (MAS) complicated by pulmonary hypertension. These cases occur infrequently. In this instance, extracorporeal membrane oxygenation (ECMO) was successfully utilized to support the infant after conventional neonatal medical support failed to yield sufficient oxygenation.

Topics: Adult; Extracorporeal Circulation; Female; Humans; Hypertension, Pulmonary; Infant, Newborn; Meconium; Oxygenators, Membrane; Pneumonia, Aspiration; Pregnancy; Pregnancy, Abdominal; Syndrome

The authors report a case of respiratory distress secondary to inhalation of meconial amniotic fluid treated by mechanical ventilation, which was complicated by severe interstitial emphysema. Treatment by pleurotomy allowed a favorable evolution. The various therapies of interstitial emphysema of the neonate, in particular surgical technics are described.

Topics: Humans; Infant, Newborn; Male; Meconium; Pneumonia, Aspiration; Pulmonary Emphysema; Respiration, Artificial; Respiratory Insufficiency

Topics: Humans; Infant, Newborn; Meconium; Pneumonia, Aspiration; Prognosis

To evaluate the effectiveness of high-frequency jet ventilation (HFJV) in the treatment of meconium aspiration, 28 puppies were assigned randomly to one of three ventilator techniques. After aspiration of 4 ml/kg of 20% meconium and baseline measurements on conventional ventilation (CV), the animals were ventilated for 6 h with either CV, HFJV, or HFJV combined with slow conventional ventilation (combined HFJV). Arterial and mixed venous blood gases, systemic and pulmonary arterial pressures, pulmonary capillary wedge pressure, and cardiac output were measured. Combined HFJV proved superior to the other two techniques, resulting in significantly better oxygenation and ventilation at a lower mean airway pressure (Paw). Oxygenation with standard HFJV was comparable to CV, producing Paw and PCO2 values intermediate between those of CV and combined HFJV. There were no significant intergroup differences in cardiac output or the incidence of pneumothorax. Improved gas exchange was attributed to alveolar recruitment and prevention of atelectasis. Alteration of the distribution and/or clearance of meconium may also be important.

Topics: Animals; Dogs; Hemodynamics; Humans; Infant, Newborn; Meconium; Pneumonia, Aspiration; Respiration; Respiration, Artificial

Topics: Acidosis; Female; Fetal Diseases; Humans; Hydrogen-Ion Concentration; Infant, Newborn; Meconium; Pneumonia, Aspiration; Pregnancy

Topics: Amniotic Fluid; Asphyxia Neonatorum; Female; Humans; Infant, Newborn; Male; Meconium; Pneumonia, Aspiration; Pregnancy; Respiratory Insufficiency; Syndrome

Topics: Female; Humans; Hypertension, Pulmonary; Infant, Newborn; Male; Meconium; Pneumonia, Aspiration; Risk; Thrombocytopenia

The pulmonary and cardiovascular effects of high-frequency jet (HFJV) and conventional (CV) ventilation were evaluated in a piglet model of meconium aspiration. A mixture of 20% human meconium and 0.9% saline solution was instilled deep into the trachea of 10 piglets, after which either HFJV or CV was administered for 4 hours. Arterial blood gases, cardiac output, mean pulmonary and systemic arterial pressures, pulmonary and systemic vascular resistances, and pulmonary mechanics were compared between groups. During the 4 hours of ventilation, PaO2 and PaCO2 were not statistically different between groups. The peak inspiratory pressure necessary to maintain PaCO2 in the preset range was approximately half as much in the HFJV group as in the CV group (P less than 0.002). Mean airway pressure was lower in the HFJV group only during the second hour (P less than 0.03). Cardiac output, mean aortic and pulmonary artery pressures, systemic and pulmonary vascular resistance, dynamic lung compliance, and pulmonary resistance were not statistically different between groups. Our results suggest that HFJV may be more effective than CV in the early stages of meconium aspiration syndrome because HFJV allows more efficient ventilation and adequate oxygenation at lower peak inspiratory pressures.

Topics: Animals; Animals, Newborn; Disease Models, Animal; Hemodynamics; Humans; Infant, Newborn; Intermittent Positive-Pressure Breathing; Meconium; Pneumonia, Aspiration; Respiration, Artificial; Respiratory Function Tests; Swine

Topics: Asphyxia Neonatorum; Humans; Hypoglycemia; Infant, Newborn; Infant, Newborn, Diseases; Infections; Meconium; Pneumonia, Aspiration; Surgical Procedures, Operative; Thyroid Gland; Thyroid Hormones; Thyrotropin; Thyroxine; Thyroxine-Binding Proteins; Triiodothyronine; Triiodothyronine, Reverse

Meconium in labor is associated with increased perinatal morbidity and mortality. To identify the infants at risk, 53 women with moderate-to-thick meconium were followed in labor after obtaining baseline fetal scalp blood pH levels. Although 28 of the newborns (53%) exhibited an arterial cord pH of less than 7.25 at delivery, there were no significant predictive variables found in the electronic fetal monitoring score, Apgar score, or mode of delivery. Nine of the infants with a pH value of less than 7.25 had meconium below the vocal cords at delivery, but none in the infants with pH levels greater than or equal to 7.25. The P50 value for cumulative acidosis is 55 minutes, indicating a more rapid deterioration than an average-for-gestational-age fetus without meconium. Therefore, the presence of thick meconium implies that fetal stress must be avoided during labor, and early intervention is warranted when there is deviation from normal labor progress or fetal heart rate pattern.

Topics: Acidosis; Adult; Female; Fetal Blood; Fetal Diseases; Fetal Heart; Fetal Monitoring; Humans; Hydrogen-Ion Concentration; Infant, Newborn; Inhalation; Meconium; Pneumonia, Aspiration; Pregnancy; Prenatal Diagnosis; Respiration

A combined obstetric-pediatric approach to tracheal toilet is said to prevent serious cases of the potentially fatal meconium aspiration syndrome. After delivery of the head a DeLee trap is used to suction the oropharynx and nasopharynx. Immediately following delivery, endotracheal suction is performed in an effort to remove any remaining meconium-stained amniotic fluid. Although routinely using this approach, we continue to have occasional cases of fatal meconium aspiration syndrome. Therefore, we reviewed the outcome of infants born through meconium-stained fluid. During a 5-year period, 1420 (15%) of 9299 live-born infants had meconium-stained fluid. Thirty (2.1%) of these 1420 developed meconium aspiration syndrome and 12 (40%) died; eight received a postmortem examination. Four had unequivocal evidence of meconium aspiration, two had large numbers of intra-alveolar squamous cells, and two had no evidence of aspiration. We conclude that aggressive airway management during and immediately after delivery does not always prevent fatal meconium aspiration syndrome.

Topics: Amniotic Fluid; Delivery, Obstetric; Humans; Infant, Newborn; Intubation, Intratracheal; Lung; Meconium; Persistent Fetal Circulation Syndrome; Pneumonia, Aspiration; Pulmonary Atelectasis; Retrospective Studies; Suction

To evaluate the effect of meconium on pulmonary surface tension properties, the mechanics of 30 excised, separated canine pulmonary lobes were studied. Meconia were blended in normal saline to produce solutions of 10% and 20%. Solutions were filtered to remove large particles and instilled endobronchially into the canine lobes. The static pressure-volume deflation curve of each lobe was determined before and 4 h after instillation of either normal saline or meconium solution. In the saline control group (eight lobes), the curve was essentially unchanged before and after instillation. In the 10% meconium group (14 lobes), the curve was significantly depressed after instillation, especially at a transpulmonary airway pressure of 10 cm H2O (p less than .05) and 5 cm H2O (p less than .005). In the 20% meconium group (eight lobes), the depression of the pressure-volume curve was essentially the same as that of the 10% solution group. It is concluded that meconium depresses the surface-active properties of the alveolar linings.

Topics: Animals; Dogs; Humans; Hydrogen-Ion Concentration; In Vitro Techniques; Infant, Newborn; Lung Volume Measurements; Meconium; Osmolar Concentration; Pneumonia, Aspiration; Pressure; Pulmonary Alveoli; Surface Tension; Time Factors

The successful management of 15 infants suffering from persistence of fetal pulmonary circulation and in severe respiratory failure is presented. The treatment regimen focused on minimizing barotrauma. Infants were intubated nasotracheally and ventilated with intermittent mandatory ventilation. Peak inspiratory pressures were determined by the clinical assessment of chest excursion. Ventilator settings and fractional inspiratory oxygen (FiO2) were selected to maintain a PaO2 between 50 and 70 mm Hg; PaCO2 was not a controlling parameter and was allowed to increase as high as 60 mm Hg. Hyperventilation and muscle relaxants were not used. High ventilator rate was used in ten infants who required high inspiratory pressure to maintain chest excursion, with a favorable response in five. Tolazoline was given to 14 infants of whom ten showed an improvement in oxygenation; dopamine was given to three infants who were oliguric. All infants survived, and only one infant developed chronic lung disease which was defined by the infant's need for supplemental oxygen beyond 30 days of life.

Topics: Birth Weight; Dopamine; Humans; Hyperventilation; Infant, Newborn; Intubation, Intratracheal; Meconium; Persistent Fetal Circulation Syndrome; Pneumonia, Aspiration; Respiration, Artificial; Respiratory Distress Syndrome, Newborn; Respiratory Insufficiency; Tolazoline

Intrapartum events were studied in 272 patients with meconium-stained amniotic fluid. All infants underwent DeLee suction followed by intubation and 58 of 272 had meconium present below the vocal cords at delivery. Neither the total duration of variable fetal heart rate decelerations or a continuous saltatory pattern nor the presence or absence of late decelerations could be related to an increased risk of meconium below the vocal cords. When a rising baseline fetal heart rate and decreased variability were present as well, a significantly greater proportion of patients had meconium below the vocal cords. Routine obstetric and pediatric suctioning did not prevent the single death that occurred in a fetus who had deep meconium aspiration in utero.

Topics: Amniotic Fluid; Female; Fetal Heart; Fetal Monitoring; Heart Rate; Humans; Infant, Newborn; Intubation, Intratracheal; Meconium; Pneumonia, Aspiration; Pregnancy; Prospective Studies; Trachea

A study was undertaken on 54 cases of meconial aspiration in order to establish a prognostic index allowing the early estimation of the risk of occurrence of refractory hypoxia. In order to do so, the factors statistically related to the occurrence of refractory hypoxia were taken into account. These factors consisted of the first arterial blood gas determination, first chest x-ray film and the initial Silverman index. A value was assigned to each parameter, with respect to the corresponding percentage of observed refractory hypoxias. The sum of the values determined the prognostic index, which varied from 6 to 25. For a high-risk threshold fixed at 15, sensibility was 78%, specificity 90% and the predictive value 84%. For an index between 16 and 20, 70% of patients developed refractory hypoxia. Occurrence was 100% for an index above 20 and refractory hypoxia occurred early. On the contrary with indexes between 6 and 14, occurrence was 15%. The calculation of this index might help clinicians in their therapeutic decisions.

Topics: Apgar Score; Humans; Hypoxia; Infant, Newborn; Meconium; Pneumonia, Aspiration; Prognosis; Respiration, Artificial; Resuscitation

Topics: Amniotic Fluid; Female; Fetal Heart; Fetus; Heart Rate; Humans; Infant, Newborn; Meconium; Movement; Narcotics; Pneumonia, Aspiration; Pregnancy; Suction; Therapeutic Irrigation; Trachea

Topics: Female; Fetal Diseases; Humans; Hyaline Membrane Disease; Infant, Newborn; Inhalation; Lung Diseases; Male; Meconium; Pneumonia, Aspiration; Pregnancy; Respiration; Syndrome

The short-term effects of muscle relaxation with pancuronium bromide on arterial blood gas values, heart rate, and arterial blood pressure were studied in 49 neonates receiving mechanical ventilation. After pancuronium administration, mean PaO2 increased from 61.9 +/- 30.0 to 80.9 +/- 52.8 mm Hg (P = 0.006), mean PaCO2 decreased from 40.1 +/- 13.0 to 37.5 +/- 13.3 mm Hg (P = 0.03), and mean heart rate rose from 146.2 +/- 24.9 to 161.0 +/- 20.5 beats/min (P less than 0.001). Arterial blood pressure did not change significantly. When results were analyzed by diagnosis (meconium aspiration syndrome, hyaline membrane disease, pneumonia), only infants with meconium aspiration syndrome had a significant improvement in oxygenation (P = 0.008). Six of 18 patients with hyaline membrane disease responded to muscle relaxation, with a decrease in PaO2 of 10 mm Hg or more. No significant correlation was found between change in PaO2 and birth weight, gestational age, postnatal age, or change in heart rate. A weak correlation (r = -0.37, P less than 0.006) was observed between change in PaO2 and change in PaCO2. Although the reasons for the divergence in response in different groups of patients are not entirely clear, the risk of deterioration with pancuronium therapy should be kept in mind, particularly if treatment in an infant with hyaline membrane disease is being considered.

Topics: Blood Gas Analysis; Blood Pressure; Heart Rate; Humans; Hyaline Membrane Disease; Hypoxia; Infant, Newborn; Meconium; Pancuronium; Pneumonia; Pneumonia, Aspiration; Respiration, Artificial

Although not proved, it is generally accepted that pulmonary vasospasm is responsible for the persistent pulmonary hypertension frequently associated with meconium aspiration. We have studied the pulmonary vasculature in 11 consecutive infants with fatal meconium aspiration, applying morphometric techniques to pulmonary arteries distended with barium gelatin before fixation. In 10 of the 11 infants, persistent pulmonary hypertension was evident clinically, with right-to-left shunting through the foramen ovale or ductus arteriosus. In all but one, severe structural abnormal muscularization of the smallest intra-acinar arteries was present. These changes must have developed before birth. In only one infant was the structure of the intra-acinar precapillary arteries virtually normal, as would be expected if vasospasm alone had caused the hypertension. The persistent pulmonary hypertension associated with fatal meconium aspiration may be the result of a structurally abnormal pulmonary microcirculation.

Topics: Female; Humans; Hypertension, Pulmonary; Infant, Newborn; Lung; Meconium; Microcirculation; Pneumonia, Aspiration; Pregnancy; Pulmonary Artery; Vascular Diseases

Ten adult cats received alternately high-frequency jet ventilation and conventional mechanical ventilation after aspirating 2 ml/kg 25% human meconium in saline. Equivalent mean airway pressures were maintained during the hourly ventilator changes. Aortic pressures, pulmonary artery pressures, and central venous pressures were continuously monitored. Cardiac outputs were measured, and pulmonary and systemic vascular resistances, intrapulmonary shunts, and alveolar arterial oxygen gradients were determined at regular intervals. During the first hour after aspiration, AaDO2 and Qs/Qt were lower during HFJV (P less than 0.05); PVR and Pa were always higher during HFJV (P less than 0.05). Overall, PVR, Pa, AaDO2, and Qs/Qt rose during HFJV; these changes occurred at equivalent Paw within 15 minutes of each ventilator change (P less than 0.05). In this meconium aspiration model, conventional mechanical ventilation was the superior form of ventilatory therapy.

Topics: Airway Resistance; Animals; Cardiac Output; Cats; Central Venous Pressure; Humans; Infant, Newborn; Meconium; Pneumonia, Aspiration; Pulmonary Wedge Pressure; Respiration, Artificial; Time Factors; Vascular Resistance

We evaluated coproporphyrin in the first urine passed by newborn infants with and without meconium aspiration, by spectrophotometric analysis and thin-layer and "high-performance" liquid chromatography. Urines of newborn infants without meconium aspiration contained only very small quantities of coproporphyrin, detected, after partial purification, by "high-performance" liquid chromatography. Urines of newborn infants with meconium aspiration contained large quantities of coproporphyrin, identified by all three techniques. Urinary coproporphyrin as measured spectrophotometrically correlates well with the "urinary meconium index," and the method is simple, rapid, and reliable, even for samples containing hemoglobin.

Topics: Chromatography, High Pressure Liquid; Chromatography, Thin Layer; Coproporphyrins; Hemoglobins; Humans; Infant, Newborn; Male; Meconium; Pneumonia, Aspiration; Porphyrins; Spectrophotometry, Ultraviolet

Aspiration of uncontaminated human amniotic fluid was investigated in adult and newborn rabbits and compared with three other experimental groups: 10% meconium solution, saline, and sham-injected controls. Fluids were injected into the trachea of adult animals (4 or 6 ml/kg body weight), newborn vaginally-delivered animals (a mean volume of 8 ml/kg), and cesarean-delivered animals before their first breath (a mean volume of 11 ml/kg). In adult animals aspirating amniotic fluid or saline, arterial PO2 measured over a 24-h period showed a mean difference between groups of less than 5% for both 4 and 6 ml/kg. Meconium aspiration produced a greater depression in PO2 than amniotic fluid aspiration (a mean difference of 16 and 31% for 4 and 6 ml/kg, respectively) and animals aspirating meconium showed a deteriorating trend over 24 h, whereas animals aspirating amniotic fluid improved. One of eight adult animals aspirating amniotic fluid died versus four of five aspirating meconium. All five animals aspirating saline 6 ml/kg survived. Lung weight and resting volume of adult animals aspirating amniotic fluid were not significantly different from animals aspirating saline or nothing. Lung pressure volume curves from adult animals aspirating amniotic fluid were nearly identical to controls. Histology showed significantly greater atelectasis in adult animals that received 6 ml/kg amniotic fluid than controls, but this was not different from saline. There was no association between the number of cells in amniotic fluid and arterial PO2 after aspiration or any other aspect of pulmonary function measured.(ABSTRACT TRUNCATED AT 250 WORDS)

Topics: Amniotic Fluid; Animals; Animals, Newborn; Lung; Meconium; Organ Size; Oxygen; Pneumonia, Aspiration; Rabbits; Sodium Chloride

Topics: Diagnosis, Differential; Humans; Infant, Newborn; Meconium; Pneumonia, Aspiration; Respiration Disorders; Spectrophotometry; Urine

Topics: Female; Humans; Infant, Newborn; Labor, Obstetric; Meconium; Pneumonia, Aspiration; Pregnancy; Suction

Topics: Apgar Score; Female; Fetal Growth Retardation; Humans; Infant, Newborn; Infant, Newborn, Diseases; Infant, Premature, Diseases; Meconium; Pneumonia, Aspiration; Pregnancy; Resuscitation

Topics: Female; Humans; Infant, Newborn; Infant, Newborn, Diseases; Male; Meconium; Pneumonia, Aspiration; Pregnancy

Topics: Gastrointestinal Hemorrhage; Humans; Infant, Newborn; Infant, Newborn, Diseases; Meconium; Pneumonia, Aspiration; Tolazoline

Topics: Apgar Score; Body Temperature Regulation; Cardiovascular Physiological Phenomena; Drug Therapy; Fetus; Humans; Infant, Newborn; Infant, Newborn, Diseases; Meconium; Pneumonia, Aspiration; Respiratory Physiological Phenomena; Resuscitation; Shock

Topics: Dyspnea; Humans; Infant, Newborn; Lung Diseases; Meconium; Pneumonia, Aspiration; Pulmonary Atelectasis; Radiography

Serial measurements of pulmonary function and arterial blood gases during the first 3 postnatal days of life were obtained in 12 infants with meconium aspiration syndrome (MAS). Nine normal neonates with similar weight and gestational age were studied as controls. Infants with MAS has significantly lower pH on day 1, and had greater P(A-a)O2 throughout the study period than that of normal controls. The PCO2 was comparable between the groups. Both dynamic lung compliance (Cdyn) and specific lung compliance (C/VL) were lower in infants with MAS as compared with those of normal infants. The functional residual capacity (FRC) for normal infants on days 1, 2, and 3 were 2.0 +/- 0.3, 2.1 +/- 0.3, and 2.2 +/- 0.3 ml/cm, respectively, and for infants with MAS were 1.8 +/- 0.4, 2.3 +!- 1.1, and 2.2 +/- 0.6 ml/cm, respectively. Radiographic hyperinflation of the lungs was seen in 6 infants with MAS on day 1; 3 were associated with high FRC (greater than 2 SD of normal) and 2 with low FRC, indicating air trapping. The early use of PEEP should be cautious if hyperinflation or air trapping is present.

Topics: Blood Gas Analysis; Humans; Infant, Newborn; Infant, Newborn, Diseases; Lung Compliance; Lung Volume Measurements; Meconium; Pneumonia, Aspiration

The authors propose a simple, quick and reliable biochemical method for diagnosis of amniotic aspiration in the newborn infant. The optical density of the infant's first urine is determined at 420, 390 and 405 nm. A urinary meconial index (IMU) is computed from these values. A meconial amniotic inhalation must be suspected if this index is greater than one. The presence of coproporphyrins identified in urine of infants having inhaled meconial amniotic fluid seems to be at the origin of the spectral characteristics of pathological urines.

Topics: Amniotic Fluid; Coproporphyrins; Densitometry; Humans; Infant, Newborn; Infant, Newborn, Diseases; Meconium; Methods; Pneumonia, Aspiration

There are contradictory descriptions in the literature about the methods as well as the sequence of clearing the upper respiratory tract of new-born babies. In order to clarify this problem anatomical, physiological and pathophysiological aspects of the fetal and neonatal respiratory system are described. Intrauterine asphyxia can lead to aspiration of amniotic fluid (containing meconium, squamous epithelium, lanugo hair). During delivery the fetal airway is cleared by compression of the thorax. Through suction of the mouth, throat and nose--in exactly this defined sequence--before birth of the thorax, aspiration of potentially damaging material can be prevented. The particular problem associated with meconium-steined amniotic fluid is described.

Topics: Amniotic Fluid; Asphyxia Neonatorum; Humans; Infant, Newborn; Meconium; Methods; Pneumonia, Aspiration; Respiratory Physiological Phenomena; Suction

Topics: Adult; Female; Humans; India; Infant, Newborn; Infant, Newborn, Diseases; Male; Meconium; Pneumonia, Aspiration; Pregnancy; Respiratory Distress Syndrome, Newborn; Retrospective Studies

To compare the efficacy of bulb and catheter suctioning of upper airway meconium in neonates, meconium labeled with technetium Tc 99m sulfur colloid was injected into the trachea and oropharynx of anesthetized kittens. Human birth conditions were simulated by an inflated blood pressure cuff around the thorax and abdomen of the animals and by partial degassing of the lungs before introduction of meconium. Distribution of meconium in the upper airway was determined by scintigraph. Catheter suction brought about a 43% decrease in radioactivity while there was only a 1% decrease after bulb suctioning. Meconium may persist in the trachea for more than 20 minutes after introduction, indicating the desirability of continued suctioning efforts in neonates with meconium aspiration syndrome. The relative safety of the two techniques was not assessed.

Topics: Airway Obstruction; Animals; Catheterization; Cats; Female; Humans; Infant, Newborn; Infant, Newborn, Diseases; Meconium; Pneumonia, Aspiration; Suction; Syndrome

Topics: Female; Fetal Hypoxia; Humans; Infant, Newborn; Meconium; Pneumonia, Aspiration; Pregnancy; Pregnancy Complications; Staining and Labeling

Topics: Amniotic Fluid; Drowning; Food; Foreign Bodies; Gases; Gastric Juice; Gastroesophageal Reflux; Humans; Infant, Newborn; Lung; Meconium; Nitrogen Dioxide; Peptide Hydrolases; Phosgene; Pneumonia; Pneumonia, Aspiration; Pneumonia, Lipid; Saliva; Smoke

Topics: Asphyxia Neonatorum; Humans; Infant, Newborn; Infant, Newborn, Diseases; Leukocyte Count; Meconium; Pneumonia, Aspiration

Topics: Female; Humans; Infant, Newborn; Infant, Newborn, Diseases; Meconium; Pneumonia, Aspiration; Pregnancy; Syndrome

Severe hypoxia unresponsive to maximum ventilatory support occurs both in idiopathic respiratory distress syndrome and meconium aspiration. We recently encountered a 980 g female infant with respiratory distress syndrome and 3 300 g female infant with meconium aspiration and persistant fetal circulation whose clinical course necessitated the use of tolazoline and dopamine to reduce pulmonary and to stabilize systemic pressures. The infant with respiratory distress syndrome responded with a PaO2 increase of 2.7 kPa while the infant with persistant fetal circulation and meconium aspiration showed a 51.6 kPa rise. Combined pharmacologic therapy may have a role in improving oxygenation status in severely hypoxemic infants receiving maximum support.

Topics: Dopamine; Female; Humans; Hypoxia; Infant, Newborn; Infant, Newborn, Diseases; Infant, Premature, Diseases; Lung; Meconium; Pneumonia, Aspiration; Respiratory Distress Syndrome, Newborn; Tolazoline; Vascular Resistance; Vasoconstriction

Aspiration of meconium by the fetus at or near delivery may be associated with high infant morbidity and mortality. The meconium aspiration syndrome (MAS) is often preventable, yet cases of MAS continue to occur. This paper describes the pathophysiology of MAS. The development of MAS involves passage of meconium by a compromised fetus and the subsequent aspiration of that meconium. Respiratory tract obstruction, hypoxia, hypercapnia, and acidosis may all result. Treatment of MAS is primarily supportive, and high mortality rates have been reported with the more severe cases. There is good evidence that careful suctioning of the infant's upper respiratory tract can in most cases prevent MAS. The suctioning, performed while the infant's head is still on the mother's perineum and prior to the first inspirations, is both a safe and effective preventive procedure.

Topics: Airway Obstruction; Female; Fetal Hypoxia; Fetus; Gastrointestinal Motility; Humans; Infant, Newborn; Meconium; Pneumonia, Aspiration; Pregnancy; Respiratory Insufficiency; Respiratory System; Suction; Syndrome

Sixteen neonatal patients diagnosed as having the meconium aspiration syndrome were selected for management with extracorporeal circulation with a membrane oxygenator (ECMO) with 8 survivors over 4 yr. All patients weighed greater than 2 kg. Each was placed in the 100% mortality group according to a Neonatal Pulmonary Insufficiency Index (NPII) based on hourly pH and FiO2 determinations. The typical patient course on ECMO was stabilization for the first 12 hr then improvement on high bypass flow rates for 12-24 hr to maintain a pAO2 for 50-60 mm Hg with minimal ventilator settings with an FiO2 of 0.3-0.4. Bypass flow rates were reduced to maintain adequate pAO2 with similar ventilator settings for another 24 hr. Survivors were taken off bypass and decannulated while on similar ventilator settings. Nonsurvivors did stabilize or improve but usually exhibited symptoms of intracranial hemorrhage by 48 hr. Intracranial hemorrhage appeared to be related to the degree of prebypass acidosis. Successful ECMO support reduced the expected mortality from severe meconium aspiration from 100% to 50%. Early institution of ECMO, before acidosis worsens, seems to be indicated to reduce the morbidity of conventional ventilator management and to prevent intracranial hemorrhage from severe prebypass acidosis. Long term followup indicates that these patients have progressed satisfactorily according to developmental testing for as long as 4 yr.

Topics: Catheterization; Extracorporeal Circulation; Female; Humans; Infant, Newborn; Infant, Newborn, Diseases; Male; Meconium; Pneumonia, Aspiration; Respiratory Insufficiency

Topics: Female; Humans; Infant, Newborn; Infant, Newborn, Diseases; Meconium; Pneumonia, Aspiration; Pregnancy

The bacteriology of tracheal aspirates from 28 intubated newborn babies was studied. There was no correlation between such colonization and the respiratory distress syndrome. Endotracheal suction of intubated infants did provide a reliable specimen source for determining the etiology of perinatal pneumonia. Presence of polymorphonuclear leukocytes in the aspirate correlated well with infection. Anaerobic bacteria were found to play a role in three of the five cases of pneumonia.

Topics: Bacteria; Critical Care; Exudates and Transudates; Female; Humans; Infant Care; Infant, Newborn; Infant, Newborn, Diseases; Intubation, Intratracheal; Male; Meconium; Pneumonia; Pneumonia, Aspiration; Respiratory Distress Syndrome, Newborn; Trachea

Topics: Asphyxia Neonatorum; Female; Gestational Age; Humans; Hyaline Membrane Disease; Infant, Low Birth Weight; Infant, Newborn; Infant, Newborn, Diseases; Male; Massachusetts; Meconium; Mediastinal Emphysema; Pneumonia, Aspiration; Pneumopericardium; Pneumothorax; Pulmonary Emphysema; Respiration, Artificial; Respiratory Function Tests; Retrospective Studies

One year's experience with MAS in a neonatal intensive-care unit is analyzed with follow-up information. Seventeen patients or 3.7% of all admissions had MAS. Four patients (23.5%) died of acute respiratory failure. Two patients with MAS and persistence of the fetal circulation required cardiac catheterization to exclude cyanotic congenital heart disease. No survivors had persistent chronic lung disease. However, two of three patients with MAS and seizures had significant psychomotor retardation at follow-up examination.

Topics: Amniotic Fluid; Developmental Disabilities; Female; Follow-Up Studies; Humans; Infant; Infant, Newborn; Inhalation; Meconium; Oxygen Inhalation Therapy; Pneumonia, Aspiration; Pregnancy; Prognosis; Radiography; Respiratory Distress Syndrome, Newborn; Syndrome

Topics: Adult; Airway Obstruction; Female; Humans; Infant, Newborn; Infant, Newborn, Diseases; Meconium; Pneumonia, Aspiration; Pregnancy

Topics: Female; Humans; Infant, Newborn; Infant, Newborn, Diseases; Male; Meconium; Pneumonia, Aspiration; Syndrome

The roentgenographic presentations of 11 newborn infants with hypoxemia secondary to pulmonary vasospasm and subsequent right-to-left shunting of blood through the foramen ovale and/or ductus arteriosus (persistent fetal circulation) are described (P. F. C. Syndrome). One infant had radiographically normal lungs, while ten had pulmonary parenchymal abnormalities including hyaline membrane disease [4], meconium aspiration syndrome [4], or an ill defined pattern of retained lung fluid [2]. The roentgenographic appearance of the lungs, however, was discordant with the severe hypoxemia observed in most. Heart size was variable but some degree of cardiomegaly was commonly present. Tolazoline, a potent vasodilator, was useful diagnostically and may have resulted in increased survival. An expanded clinical and roentgeonographic concept of the PFC syndrome is suggested.

Topics: Female; Humans; Hyaline Membrane Disease; Hypertension, Pulmonary; Hypoxia; Infant, Newborn; Male; Meconium; Pneumonia, Aspiration; Radiography; Syndrome; Truncus Arteriosus, Persistent

Routine intrapartum pharyngeal suctioning with a DeLee catheter of infants with meconium staining has significantly reduced the incidence and severity of meconium aspiration syndrome (MAS). There have been no adverse sequelae to this procedure, which is carried out while the infant's head is on the perineum, prior to the onset of respirations. Routine suctioning of the trachea under direct vision after delivery is rarely necessary but should be done if meconium is visualized at the vocal cords. Tracheobronchial lavage with saline may add to the respiratory morbidity. No deaths or severe cases of MAS have occurred since institution of the obstetric suctioning procedure.

Topics: Female; Humans; Infant, Newborn; Infant, Newborn, Diseases; Intubation, Intratracheal; Meconium; Pneumonia, Aspiration; Pregnancy; Sodium Chloride; Suction; Syndrome; Therapeutic Irrigation

In a retrospective analysis of infants born with meconium staining over an 18-month period at Cook County Hospital, 32 infants met two of the three criteria for the diagnosis of meconium aspiration syndrome: (1) history of meconium in the oropharynx or trachea; (2) clinical evidence of respiratory distress; and (3) x-ray evidence of aspiration pneumonia. Seventeen infants developed respiratory failure; nine of these infants died. One infant without respiratory failure died of sepsis. Analysis of sequential arterial blood pH and gas tension showed that nonsurviving infants had persistently high PCO2 and A-a gradient in spite of initiation of assisted ventilation. These changes seem to be related to severe right-to-left shunting and ventilation perfusion abnormalities. The data further suggest that asphyxia and acidosis occur well before the infant is born and that intrapartum monitoring to recognize fetal asphyxia may help in improving morbidity and mortality from meconium aspiration syndrome.

Topics: Blood Gas Analysis; Humans; Hydrogen-Ion Concentration; Infant, Newborn; Infant, Newborn, Diseases; Inhalation; Intermittent Positive-Pressure Breathing; Intubation, Intratracheal; Meconium; Pneumonia, Aspiration; Radiography; Respiration; Respiratory Distress Syndrome, Newborn; Resuscitation; Syndrome; Ventilators, Mechanical

We performed a retrospective study of the morbidity and mortality rates of 125 infants, born through meconium-stained amniotic fluid, and admitted to the newborn intensive-care unit for observation. A comparison was made of maternal age, history of toxemia, type of anesthesia, duration of analgesia, presence of cord complications, abnormalities of fetal heart rate, duration of meconium staining, birth weight, gestational age, 1 and 5 minute Apgar scores, and type of resuscitation between infants who were symptomatic or asymptomatic in the unit. Forty-three developed respiratory distress (symptomatic) and eight died; 82 were asymptomatic. The only difference between the two groups was a history of immediate tracheal suction in the delivery room. Of 97 infants receiving immediate tracheal suction, 27 became symptomatic and one died--an infant with Down's syndrome and endocardial cushion defect. On the other hand, of 28 infants who did not receive immediate tracheal suction, 16 became symptomatic and seven died of massive meconium aspiration pneumonitis (P less than 0.001). We concluded that in infants born through meconium-stained amniotic fluid, immediate tracheal suction is a safe procedure that significantly lowers the morbidity and mortality rates and produces no further respiratory depression of the infant.

Topics: Amniotic Fluid; Apgar Score; Autopsy; Birth Weight; Catheterization; Drainage; Female; Gestational Age; Humans; Infant, Newborn; Infant, Newborn, Diseases; Inhalation; Intubation, Intratracheal; Laryngoscopy; Meconium; Methods; Pneumonia, Aspiration; Pregnancy; Respiratory Distress Syndrome, Newborn; Retrospective Studies; Trachea

Topics: Birth Weight; Chromatography, Thin Layer; Gestational Age; Humans; Infant, Newborn; Intubation, Intratracheal; Lung; Meconium; Pharynx; Phosphatidylcholines; Pneumonia; Pneumonia, Aspiration; Prognosis; Respiratory Distress Syndrome, Newborn; Sphingomyelins; Trachea

Topics: Cysts; Diaphragmatic Eventration; Heart Defects, Congenital; Hernia, Diaphragmatic; Humans; Hyaline Membrane Disease; Infant, Newborn; Meconium; Mediastinal Emphysema; Pneumonia, Aspiration; Pneumothorax; Pulmonary Emphysema; Radiography; Respiratory Distress Syndrome, Newborn

Topics: Humans; Infant, Newborn; Infant, Newborn, Diseases; Meconium; Nitrogen; Pneumonia, Aspiration; Pulmonary Alveoli; Respiratory Insufficiency; Ventilation-Perfusion Ratio

Topics: Asphyxia Neonatorum; Brain; Gestational Age; Humans; Hyaline Membrane Disease; Infant, Newborn; Lung; Male; Meconium; Pneumonia, Aspiration

Topics: Humans; Infant, Newborn; Infant, Premature, Diseases; Meconium; Pneumonia, Aspiration

Topics: Animals; Female; Hyperbaric Oxygenation; Meconium; Pneumonia, Aspiration; Pregnancy; Rabbits; Respiratory Tract Diseases; Sodium Chloride; Solutions

Topics: Adult; Amniotic Fluid; Female; Fetal Death; Humans; Meconium; Pneumonia, Aspiration; Pregnancy