Persistent fetal circulation

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Persistent fetal circulation
Other namesPersistent pulmonary hypertension of the newborn
Specialty Pediatrics   OOjs UI icon edit-ltr-progressive.svg

Persistent fetal circulation is a condition caused by a failure in the systemic circulation and pulmonary circulation to convert from the antenatal circulation pattern to the "normal" pattern. Infants experience a high mean arterial pulmonary artery pressure and a high afterload at the right ventricle. This means that the heart is working against higher pressures, which makes it more difficult for the heart to pump blood. [1]

Contents

In a fetus, there is high pulmonary vascular resistance (PVR) and low pulmonary blood flow as the fetus does not use the lungs for oxygen transfer, but instead relies on the placenta for oxygen. When the baby is born, the lungs are needed for oxygen transfer and need high blood flow which is encouraged by low PVR. The failure of the circulatory system of the newborn to adapt to these changes by lowering PVR leads to persistent fetal circulation. [2] The newborn is therefore born with elevated PVR, which leads to pulmonary hypertension. Because of this, the condition is also widely known as persistent pulmonary hypertension of the newborn (PPHN). [3] This condition can be either acute or chronic, and is associated with significant morbidity and mortality. [1]

Presentation

Complications

PPHN can range from mild to severe disease. In the most severe form, infants experience severe hypoxemia resulting in cardiac and pulmonary complications. [4] As a result of low oxygen levels, infants with PPHN are at an increased risk of developing complications, such as asphyxia, chronic lung disease, neurodevelopment issues, and death. [5]

Nosocomial infections are another type of complication that may contribute to mortality in someone with PPHN. If the newborn acquires an infection while hospitalized, this could result in deterioration of the condition even after days of improvement. [6]

Pathophysiology

Typically, a fetus experiences pulmonary hypertension in utero since it is relying on the placenta for oxygen rather than its lungs. When the fetus is born, it is no longer attached to the placenta and must use the lungs to receive oxygen. To facilitate this change from fetus to newborn, the baby must change from a state of high PVR to low PVR, allowing for increased blood flow to circulate throughout the body. [3] This inability of the newborn to adapt to these changes is caused by various processes, such as:

Diagnosis

To help with diagnosis, the clinician can watch out for predisposing factors, such as: birth asphyxia, meconium aspiration, use of NSAIDs (non steroidal anti-inflammatory drugs) and SSRIs (selective serotonin reuptake inhibitors) by the mother, and early onset sepsis or pneumonia. [8] To diagnose a fetus with pulmonary hypertension, PVR must be higher than systemic vascular resistance, resulting in high afterload and decreased systemic blood flow. This causes a significant decrease in oxygen concentration, which clinically manifests as insufficient blood flow to the lower body, while there is adequate circulation to the head and right side of the body. [9] Other echocardiographic findings in PPHN include right ventricular hypertrophy, deviation of the ventricular septum, tricuspid regurgitation, and shunting at the patent foramen ovale. [3]

Other clinical signs that may signify PPHN are respiratory distress, partial pressure of oxygen greater than 100 mg and elevated partial pressure of carbon dioxide. [3] A gradient of 10% or more in oxygenation saturation between simultaneous preductal and postductal arterial blood gas values in absence of structural heart disease documents persistent fetal circulation. [10] Since this may be a sign of other conditions, persistent fetal circulation must also be characterized by enlargement of right and left ventricles often confirmed through a definitive ECG. [8]

Persistent fetal circulation in neonates can be reversible or irreversible depending on the classified etiology listed above. If related to pulmonary disorders, the amount of lung damage dictates whether or not treatment is efficacious in reversing newborn lung insufficiency. Other causes for acute pulmonary hypertension include: infection, endocrine disorders, and drug injury. [11]

Examples of cases with newborns who with sustained fetal circulation are pulmonary hypoplasia and genetic abnormalities. [11]

Treatment

Treatment aims to increase the amount of oxygen in the blood and reverse any causes of hypoxia as well as gain adequate perfusion. [5]

Common treatments include: [12]

The therapies available to manage PPHN include high frequency ventilation, surfactant instillation, pulmonary vasodilators, and extracorporeal membrane oxygenation. [14]

iNO is the preferred medication for PPHN due to its ability to more selectively cause pulmonary vasodilation in comparison to intravenous vasodilators. While this medication decreases the need for extracorporeal membrane oxygenation or extracorporeal life support, it has not been shown to reduce mortality. Intravenous sildenafil has been shown to have similar efficacy and is becoming more commonly used as treatment for PPHN. [15]

Assessment of the efficacy of these treatments includes chest radiographs and arterial blood gases. Signs of inefficacious treatments include prolonged capillary filling time, low pulse volume, low blood pressure, and sustained metabolic acidosis. [1]

In addition to treating the direct effects of this condition, other management strategies are implemented concurrently to stabilize the newborn.These include, but are not limited to nutritional support, reduction of stressful environment, gentle sedation, monitoring/treating acidosis and establishing normal systemic blood pressure. [4]

Challenges in developing countries:

PPHN has been seen more frequently in developing countries or resource-poor areas, though it occurs across the globe. Treating this condition often involves large interdisciplinary teams, which is not always possible in developing countries. In low-resource environments, it is recommended to focus on five main bundles of management: [16]

Epidemiology

It occurs in 1–2 infants per 1000 live births. [17] It is more common in males and in areas with higher altitudes. [9] Additionally, two percent of infants with respiratory distress syndrome develop PPHN. [3]

Related Research Articles

<span class="mw-page-title-main">Meconium aspiration syndrome</span> Medical condition affecting newborn infants

Meconium aspiration syndrome (MAS) also known as neonatal aspiration of meconium is a medical condition affecting newborn infants. It describes the spectrum of disorders and pathophysiology of newborns born in meconium-stained amniotic fluid (MSAF) and have meconium within their lungs. Therefore, MAS has a wide range of severity depending on what conditions and complications develop after parturition. Furthermore, the pathophysiology of MAS is multifactorial and extremely complex which is why it is the leading cause of morbidity and mortality in term infants.

<span class="mw-page-title-main">Intrauterine growth restriction</span> Medical condition

Intrauterine growth restriction (IUGR), or fetal growth restriction, refers to poor growth of a fetus while in the womb during pregnancy. IUGR is defined by clinical features of malnutrition and evidence of reduced growth regardless of an infant's birth weight percentile. The causes of IUGR are broad and may involve maternal, fetal, or placental complications.

<span class="mw-page-title-main">Patent ductus arteriosus</span> Condition wherein the ductus arteriosus fails to close after birth

Patent ductus arteriosus (PDA) is a medical condition in which the ductus arteriosus fails to close after birth: this allows a portion of oxygenated blood from the left heart to flow back to the lungs through the aorta, which has a higher blood pressure, to the pulmonary artery, which has a lower blood pressure. Symptoms are uncommon at birth and shortly thereafter, but later in the first year of life there is often the onset of an increased work of breathing and failure to gain weight at a normal rate. With time, an uncorrected PDA usually leads to pulmonary hypertension followed by right-sided heart failure.

<span class="mw-page-title-main">Pulmonary hypertension</span> Increased blood pressure in lung arteries

Pulmonary hypertension is a condition of increased blood pressure in the arteries of the lungs. Symptoms include shortness of breath, fainting, tiredness, chest pain, swelling of the legs, and a fast heartbeat. The condition may make it difficult to exercise. Onset is typically gradual.

<span class="mw-page-title-main">Ductus arteriosus</span> Blood vessel connecting the pulmonary artery to the proximal descending aorta

The ductus arteriosus, also called the ductus Botalli, named after the Italian physiologist Leonardo Botallo, is a blood vessel in the developing fetus connecting the trunk of the pulmonary artery to the proximal descending aorta. It allows most of the blood from the right ventricle to bypass the fetus's fluid-filled non-functioning lungs. Upon closure at birth, it becomes the ligamentum arteriosum.

<span class="mw-page-title-main">Blue baby syndrome</span> Two situations that lead to cyanosis in infants

Blue baby syndrome can refer to conditions that cause cyanosis, or blueness of the skin, in babies as a result of low oxygen levels in the blood. This term has traditionally been applied to cyanosis as a result of:

  1. Cyanotic heart disease, which is a category of congenital heart defect that results in low levels of oxygen in the blood. This can be caused by either reduced blood flow to the lungs or mixing of oxygenated and deoxygenated blood.
  2. Methemoglobinemia, which is a disease defined by high levels of methemoglobin in the blood. Increased levels of methemoglobin prevent oxygen from being released into the tissues and result in hypoxemia.
<span class="mw-page-title-main">Infant respiratory distress syndrome</span> Human disease affecting newborns

Infantile respiratory distress syndrome (IRDS), also called respiratory distress syndrome of newborn, or increasingly surfactant deficiency disorder (SDD), and previously called hyaline membrane disease (HMD), is a syndrome in premature infants caused by developmental insufficiency of pulmonary surfactant production and structural immaturity in the lungs. It can also be a consequence of neonatal infection and can result from a genetic problem with the production of surfactant-associated proteins.

At the end of pregnancy, the fetus must take the journey of childbirth to leave the reproductive mother. Upon its entry to the air-breathing world, the newborn must begin to adjust to life outside the uterus. This is true for all viviparous animals; this article discusses humans as the most-researched example.

<span class="mw-page-title-main">Neonatal intensive care unit</span> Intensive care unit specializing in the care of ill or premature newborn infants

A neonatal intensive care unit (NICU), also known as an intensive care nursery (ICN), is an intensive care unit (ICU) specializing in the care of ill or premature newborn infants. The NICU is divided into several areas, including a critical care area for babies who require close monitoring and intervention, an intermediate care area for infants who are stable but still require specialized care, and a step down unit where babies who are ready to leave the hospital can receive additional care before being discharged.

<span class="mw-page-title-main">Hydrops fetalis</span> Human disease of fetuses

Hydrops fetalis or hydrops foetalis is a condition in the fetus characterized by an accumulation of fluid, or edema, in at least two fetal compartments. By comparison, hydrops allantois or hydrops amnion is an accumulation of excessive fluid in the allantoic or amniotic space, respectively.

<span class="mw-page-title-main">Hypoplastic left heart syndrome</span> Type of congenital heart defect

Hypoplastic left heart syndrome (HLHS) is a rare congenital heart defect in which the left side of the heart is severely underdeveloped and incapable of supporting the systemic circulation. It is estimated to account for 2-3% of all congenital heart disease. Early signs and symptoms include poor feeding, cyanosis, and diminished pulse in the extremities. The etiology is believed to be multifactorial resulting from a combination of genetic mutations and defects resulting in altered blood flow in the heart. Several structures can be affected including the left ventricle, aorta, aortic valve, or mitral valve all resulting in decreased systemic blood flow.

<span class="mw-page-title-main">Congenital diaphragmatic hernia</span> Medical condition

Congenital diaphragmatic hernia (CDH) is a birth defect of the diaphragm. The most common type of CDH is a Bochdalek hernia; other types include Morgagni hernia, diaphragm eventration and central tendon defects of the diaphragm. Malformation of the diaphragm allows the abdominal organs to push into the chest cavity, hindering proper lung formation.

<span class="mw-page-title-main">Pulmonary atresia</span> Medical condition

Pulmonary atresia is a congenital malformation of the pulmonary valve in which the valve orifice fails to develop. The valve is completely closed thereby obstructing the outflow of blood from the heart to the lungs. The pulmonary valve is located on the right side of the heart between the right ventricle and pulmonary artery. In a normal functioning heart, the opening to the pulmonary valve has three flaps that open and close.

<span class="mw-page-title-main">Fetal circulation</span> Circulatory system of fetuses

In humans, the circulatory system is different before and after birth. The fetal circulation is composed of the placenta, umbilical blood vessels encapsulated by the umbilical cord, heart and systemic blood vessels. A major difference between the fetal circulation and postnatal circulation is that the lungs are not used during the fetal stage resulting in the presence of shunts to move oxygenated blood and nutrients from the placenta to the fetal tissue. At birth, the start of breathing and the severance of the umbilical cord prompt various changes that quickly transform fetal circulation into postnatal circulation.

<span class="mw-page-title-main">Respiratory disease</span> Disease of the respiratory system

Respiratory diseases, or lung diseases, are pathological conditions affecting the organs and tissues that make gas exchange difficult in air-breathing animals. They include conditions of the respiratory tract including the trachea, bronchi, bronchioles, alveoli, pleurae, pleural cavity, the nerves and muscles of respiration. Respiratory diseases range from mild and self-limiting, such as the common cold, influenza, and pharyngitis to life-threatening diseases such as bacterial pneumonia, pulmonary embolism, tuberculosis, acute asthma, lung cancer, and severe acute respiratory syndromes, such as COVID-19. Respiratory diseases can be classified in many different ways, including by the organ or tissue involved, by the type and pattern of associated signs and symptoms, or by the cause of the disease.

<span class="mw-page-title-main">Intrauterine hypoxia</span> Medical condition when the fetus is deprived of sufficient oxygen

Intrauterine hypoxia occurs when the fetus is deprived of an adequate supply of oxygen. It may be due to a variety of reasons such as prolapse or occlusion of the umbilical cord, placental infarction, maternal diabetes and maternal smoking. Intrauterine growth restriction may cause or be the result of hypoxia. Intrauterine hypoxia can cause cellular damage that occurs within the central nervous system. This results in an increased mortality rate, including an increased risk of sudden infant death syndrome (SIDS). Oxygen deprivation in the fetus and neonate have been implicated as either a primary or as a contributing risk factor in numerous neurological and neuropsychiatric disorders such as epilepsy, attention deficit hyperactivity disorder, eating disorders and cerebral palsy.

<span class="mw-page-title-main">Pulmonary hypoplasia</span> Congenital disorder of respiratory system

Pulmonary hypoplasia is incomplete development of the lungs, resulting in an abnormally low number or small size of bronchopulmonary segments or alveoli. A congenital malformation, it most often occurs secondary to other fetal abnormalities that interfere with normal development of the lungs. Primary (idiopathic) pulmonary hypoplasia is rare and usually not associated with other maternal or fetal abnormalities.

Alveolar capillary dysplasia (ACD) is a rare, congenital diffuse lung disease characterized by abnormal blood vessels in the lungs that cause highly elevated pulmonary blood pressure and an inability to effectively oxygenate and remove carbon dioxide from the blood. ACD typically presents in newborn babies within hours of birth as rapid and labored breathing, blue-colored lips or skin, quickly leading to respiratory failure and death. Atypical forms of ACD have been reported with initially milder symptoms and survival of many months before the onset of respiratory failure or lung transplantation.

Major aortopulmonary collateral arteries are arteries that develop to supply blood to the lungs when native pulmonary circulation is underdeveloped. Instead of coming from the pulmonary trunk, supply develops from the aorta and other systemic arteries.

<span class="mw-page-title-main">High-risk pregnancy</span> Medical condition

A high-risk pregnancy is one where the mother or the fetus has an increased risk of adverse outcomes compared to uncomplicated pregnancies. No concrete guidelines currently exist for distinguishing “high-risk” pregnancies from “low-risk” pregnancies; however, there are certain studied conditions that have been shown to put the mother or fetus at a higher risk of poor outcomes. These conditions can be classified into three main categories: health problems in the mother that occur before she becomes pregnant, health problems in the mother that occur during pregnancy, and certain health conditions with the fetus.

References

  1. 1 2 3 4 Jain A, McNamara PJ (August 2015). "Persistent pulmonary hypertension of the newborn: Advances in diagnosis and treatment". Seminars in Fetal & Neonatal Medicine. 20 (4): 262–71. doi:10.1016/j.siny.2015.03.001. PMID   25843770. S2CID   11356506.
  2. ↑ Latham GJ, Yung D (May 2019). "Current understanding and perioperative management of pediatric pulmonary hypertension". Pediatric Anesthesia. 29 (5): 441–456. doi:10.1111/pan.13542. PMID   30414333. S2CID   53248786.
  3. 1 2 3 4 5 Mathew B, Lakshminrusimha S (July 2017). "Persistent Pulmonary Hypertension in the Newborn". Children. 4 (8): 63. doi: 10.3390/children4080063 . PMC   5575585 . PMID   28788074.
  4. 1 2 Fuloria M, Aschner JL (August 2017). "Persistent pulmonary hypertension of the newborn". Seminars in Fetal & Neonatal Medicine. 22 (4): 220–226. doi:10.1016/j.siny.2017.03.004. PMID   28342684.
  5. 1 2 Pedersen J, Hedegaard ER, Simonsen U, Krüger M, Infanger M, Grimm D (October 2018). "Current and Future Treatments for Persistent Pulmonary Hypertension in the Newborn". Basic & Clinical Pharmacology & Toxicology. 123 (4): 392–406. doi: 10.1111/bcpt.13051 . PMID   29855164. S2CID   46918462.
  6. ↑ Lai MY, Chu SM, Lakshminrusimha S, Lin HC (February 2018). "Beyond the inhaled nitric oxide in persistent pulmonary hypertension of the newborn". Pediatrics and Neonatology. 59 (1): 15–23. doi: 10.1016/j.pedneo.2016.09.011 . PMID   28923474.
  7. ↑ Graves ED, Redmond CR, Arensman RM (March 1988). "Persistent pulmonary hypertension in the neonate". Chest. 93 (3): 638–41. doi:10.1378/chest.93.3.638. PMID   3277808. Archived from the original on 2014-04-24. Retrieved 2014-04-24.
  8. 1 2 Sharma M, Mohan KR, Narayan S, Chauhan L (October 2011). "Persistent pulmonary hypertension of the newborn: a review". Medical Journal, Armed Forces India. 67 (4): 348–53. doi:10.1016/S0377-1237(11)60082-8. PMC   4920635 . PMID   27365845.
  9. 1 2 D'cunha C, Sankaran K (December 2001). "Persistent fetal circulation". Paediatrics & Child Health. 6 (10): 744–50. doi:10.1093/pch/6.10.744. PMC   2805987 . PMID   20084150.
  10. ↑ Lakshminrusimha S, Kumar VH (2011-01-01). "Chapter 48 - Diseases of Pulmonary Circulation". In Fuhrman BP, Zimmerman JJ (eds.). Pediatric Critical Care (Fourth ed.). Saint Louis: Mosby. pp. 632–656. doi:10.1016/b978-0-323-07307-3.10048-5. ISBN   978-0-323-07307-3.
  11. 1 2 Abman, Steven H. (2006-04-01). "Persistent Pulmonary Hypertension of the Newborn: Pathophysiology and Treatment". Advances in Pulmonary Hypertension. 5 (2): 22–30. doi: 10.21693/1933-088x-5.2.22 . ISSN   1933-088X.
  12. ↑ Luecke C, McPherson C (May 2017). "Treatment of Persistent Pulmonary Hypertension of the Newborn: Use of Pulmonary Vasodilators in Term Neonates". Neonatal Network. 36 (3): 160–168. doi:10.1891/0730-0832.36.3.160. PMID   28494828. S2CID   3917195.
  13. ↑ Lakshminrusimha S, Mathew B, Leach CL (April 2016). "Pharmacologic strategies in neonatal pulmonary hypertension other than nitric oxide". Seminars in Perinatology. 40 (3): 160–73. doi:10.1053/j.semperi.2015.12.004. PMC   4808469 . PMID   26778236.
  14. ↑ Walsh MC, Stork EK (September 2001). "Persistent pulmonary hypertension of the newborn. Rational therapy based on pathophysiology". Clinics in Perinatology. 28 (3): 609–27, vii. doi:10.1016/s0095-5108(05)70109-3. PMID   11570157.
  15. ↑ Steinhorn RH (March 2010). "Neonatal pulmonary hypertension". Pediatric Critical Care Medicine. 11 (2 Suppl): S79-84. doi:10.1097/PCC.0b013e3181c76cdc. PMC   2843001 . PMID   20216169.
  16. ↑ Nakwan N (December 2018). "The Practical Challenges of Diagnosis and Treatment Options in Persistent Pulmonary Hypertension of the Newborn: A Developing Country's Perspective". American Journal of Perinatology. 35 (14): 1366–1375. doi:10.1055/s-0038-1660462. PMID   29920641. S2CID   49315233.
  17. ↑ Chambers CD, Hernandez-Diaz S, Van Marter LJ, Werler MM, Louik C, Jones KL, Mitchell AA (February 2006). "Selective serotonin-reuptake inhibitors and risk of persistent pulmonary hypertension of the newborn". The New England Journal of Medicine. 354 (6): 579–87. doi: 10.1056/NEJMoa052744 . PMID   16467545.

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