morphine and Hypertension--Pulmonary

The meconium aspiration syndrome (MAS) is a common problem that continues to concern perinatologists and neonatologists. MAS is defined as respiratory distress in an infant born through meconium-stained amniotic fluid (MSAF) whose symptoms cannot be otherwise explained. This disorder may be life threatening, complicated by respiratory failure, pulmonary air leaks and persistent pulmonary hypertension. Approaches to the prevention of MAS have changed over time with collaboration between obstetricians and pediatricians forming the foundations for care. This report details the management of babies delivered with associated MSAF before the accumulation of evidence for best practice through appropriately powered, prospective randomized controlled trials.

Topics: Amniotic Fluid; Evidence-Based Medicine; Extracorporeal Membrane Oxygenation; Glucocorticoids; Humans; Hypertension, Pulmonary; Infant, Newborn; Meconium; Meconium Aspiration Syndrome

Topics: Bronchopulmonary Dysplasia; Humans; Hyaline Membrane Disease; Hypertension, Pulmonary; Infant, Newborn; Meconium; Respiratory Distress Syndrome, Newborn

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

Several studies of vasoactive intestinal polypeptide (VIP) demonstrated its potent vasodilative effects on pulmonary and systemic circulation. However, no hemodynamic studies were performed to depict the effects of VIP in an in vivo model of pulmonary arterial hypertension (PAH), thereby limiting a complete understanding of the overall hemodynamic effects of VIP in PAH.. The pulmonary and systemic hemodynamic effects of intravenous infusion of 100 ng/kg per minute of VIP in control and pulmonary hypertensive piglets at 6 to 8 weeks of age were assessed. Pulmonary arterial hypertension was induced after the instillation of meconium solution in the subjects' trachea and was characterized by the establishment of a persistently elevated pulmonary arterial pressure, diminished cardiac output, and elevated pulmonary-to-systemic vascular resistance (PVR/SVR) ratio.. Continuous intravenous infusion of VIP markedly decreased PVR/SVR ratio in pulmonary hypertensive subjects; however, it lowered blood pressure without causing any significant changes in PVR/SVR ratio in control subjects. Collectively, these results suggest an overall pulmonary vasodilative effect of VIP in PAH.

Topics: Analysis of Variance; Animals; Cardiac Output; Disease Models, Animal; Heart Rate; Humans; Hypertension, Pulmonary; Infant, Newborn; Infusions, Intravenous; Meconium; Random Allocation; Swine; Vascular Resistance; Vasoactive Intestinal Peptide

Our objective was to study meconium-induced lung injury in isolated perfused rat lungs exposed to anoxia. Our working hypothesis was that meconium-induced lung injury is independent of preexisting hypoxia, and that hypoxia will increase severity of lung injury observed after meconium aspiration. We compared five different groups of animals (n = 5) for pulmonary arterial pressure (PAP), weight lung changes, and TNFalpha expression. Group I had lungs instilled with 4 ml of normal saline. Group II had lungs exposed to 5 min of anoxia. Group III had lungs instilled with 4 ml of 30% filtered human meconium. Group IV had lungs exposed to 5 min of anoxia and then instilled with 4 ml of 30% filtered human meconium. Group V had lungs instilled with 4 ml of 30% unfiltered human meconium. Our subjects were adult Sprague-Dawley rats. The isolated rat lung model was prepared according to Levey and Gast (J Appl Physiol 1966;21:313-316). Lungs were ventilated with room air. Anoxia was caused by the use of N(2). The pulmonary artery was cannulated, and pulmonary arterial pressure and lung weight were measured. Lung weight and pulmonary arterial pressure were monitored for 120 min, and TNFalpha levels were measured in effluent at 15, 30, 60, and 120 min. Experiments were done at the Michael Reese Hospital (Chicago, IL). At the end of the experiment, PAP reached its highest values in group V (10.0 +/- 1.7 mmHg). Final PAPs in groups I-IV were: 4.85 +/- 0.3, 4.99 +/- 0.4, 5.93 +/- 0.3, and 7.25 +/- 0.51 mmHg, respectively). Lung wet weight increased significantly only in groups IV and V vs. group I; at 120 min, they were: 0.96 +/- 0.3 g, P < 0.01, and 1.5 g +/- 0.2 g, P < 0.01, respectively. TNFalpha levels did not change significantly over time in group I. TNFalpha is a marker as well as proprietor of pulmonary inflammatory response. TNFalpha reached its highest levels in groups IV and V: 595 and 753 pg/ml at 120 min, respectively. In conclusion, a short episode of anoxia prior to meconium aspiration may increase lung sensitivity to meconium-induced lung injury. This effect may be moderated by the TNFalpha present in the pulmonary circulation.

Topics: Animals; Animals, Newborn; Filtration; Hypertension, Pulmonary; Hypoxia; In Vitro Techniques; Inhalation; Lung Diseases; Meconium; Rats; Rats, Sprague-Dawley; Tumor Necrosis Factor-alpha

Extracorporeal membrane oxygenation (ECMO) is a lifesaving therapy for neonatal pulmonary hypertension but carries a significant risk for transfusion-related complications. Packed red blood cell (PRBC) and platelet exposure were quantified and reviewed in 17 ECMO survivors prior (Group I, n = 9) and subsequent to (Group II, n = 8) changes in transfusion protocols. Blood product requirements included ECMO circuit priming, maintenance of haematocrit > 0.40 or platelet count > 50 x 10(9)/l, and colloid volume expansion. Group I was exposed to 13.8 +/- 10.2 (x +/- SD) different PRBC units. In Group II, multiple transfusions from single donor units decreased exposure 71% to 3.9 +/- 0.7 units (P < 0.05). Decreases in blood withdrawn (11%) and transfusion volume (7%) were coincident with a 15% reduction in mean bypass time. Platelet volume transfusion decreased from 159 +/- 213 to 93 +/- 64 ml using volume-reduced platelet packs. Total transfusion exposure decreased 59% from 20.8 +/- 17.8 units to 8.6 +/- 2.4 donor units. No transfusion complications occurred during the aggregate 1,926 h on bypass. We conclude that neonates on ECMO have a significant transfusion exposure risk increasing with prolonged duration of ECMO therapy. In addition we noted that concentrated platelet packs decreased transfusion volume by 41%, and multiple PRBC transfusions from single donor units decreased donor exposure by 71% while both strategies decreased the overall transfusion exposure risk by 59%.

Topics: Blood Component Transfusion; Blood Transfusion; Erythrocyte Transfusion; Extracorporeal Membrane Oxygenation; Female; Humans; Hypertension, Pulmonary; Infant, Newborn; Inhalation; Male; Meconium; Platelet Transfusion; Prospective Studies; Respiratory Distress Syndrome, Newborn; Respiratory Insufficiency; Retrospective Studies; Risk; Sepsis; Transfusion Reaction

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

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

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

Three patients with Meconium Aspiration Syndrome (S.A.M.) and severe hypoxemia are reported. From the first hours of life they needed mechanical ventilation, showing no improvement in PaO2 in spite of usual respiratory support measures. In one case, pulmonary hypertension and ductal right to left shunt through ductus arteriosus and foramen ovale was objetivated by cardiac catheterization. Following intravenous prefusion of a pulmonary vasodilator (Tolazoline) patients showed a clinical amelioration and a definite increase in PaO2. Results and evolution with the use of this drug are commented.

Topics: Ductus Arteriosus, Patent; Female; Humans; Hyaline Membrane Disease; Hypertension, Pulmonary; Hypoxia; Infant, Newborn; Injections, Intravenous; Male; Meconium; Oxygen; Partial Pressure; Tolazoline

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

Topics: Apgar Score; Asphyxia Neonatorum; Birth Weight; Carbon Dioxide; Cardiac Catheterization; Cyanosis; Diagnosis, Differential; Female; Follow-Up Studies; Gestational Age; Heart Defects, Congenital; Humans; Hypertension, Pulmonary; Infant, Newborn; Infant, Newborn, Diseases; Male; Meconium; Obstetric Labor Complications; Oxygen; Partial Pressure; Pregnancy; Pulmonary Artery; Radiography