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Introduction
Hyaline membrane disease (HMD) is defined as respiratory distress in a newborn whose lungs are not fully developed. It is a very common problem seen in premature babies.
It is named as hyaline membranes disease because when the alveoli collapse, the damaged cells that collect in the airway tract are called hyaline membranes. They obstruct the airway, making it more difficult for the baby to breathe.
Newborn may require extra oxygen and help with breathing. | |
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Causes & Risk factors
Prematurity:
HMD occurs due to the deficiency of surfactant in the immature lungs. Surfactant is a protective substance in the lungs that lowers the surface tension in the airways and helps keep the air sacs (lung alveoli) in the lungs open, preventing them from collapsing.HMD Commonly seen in premature babies born before 28 weeks of pregnancy because of poor or no production of surfactant this early and is seen rarely in babies born at full term (40 weeks). More premature the baby is, higher the chances of developing HMD.
Other risk factors include:
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Delivery by caesarean section
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Similar history of birth of a sibling with HMD
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Cold environment (suppresses surfactant production)
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Multiple pregnancy
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Diabetic mother
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Decreased blood flow to the baby during delivery
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Symptoms and signs
Symptoms may vary from baby to baby and the more common ones include:
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Difficulty in breathing at birth, that worsens with time
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Cyanosis (bluish discolouration of skin and mucous membranes)
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Nasal flaring
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Tachypnea (rapid breathing)
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Grunting sound during exhaling (breathing out)
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Retracting or pulling in of the chest during breathing
The condition of the newborn worsens over the first 48 to 72 hours, and improves with treatment. | |
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Diagnosis
It depends upon following factors:
History:
Suggestive of prematurity, very low birth weight.
Clinical examination:
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Bluish discoloration of skin and/or tongue caused by restricted oxygen supply.
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Fast breathing pattern (tachypnea)
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Chest retractions and flaring of nostrils
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Chest X-ray, arterial blood gas analysis and/or ECG are performed to confirm the diagnosis.
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Investigations
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Chest x-ray - Shows typical ‘ground glass’ appearance.
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Arterial blood gases (ABG) – may show deficiency of oxygen and increased carbon dioxide.
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Echocardiography (ECG) - to rule out heart problems (that might cause similar symptoms)
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Treatment
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An endotracheal (ET) tube or breathing tube is positioned into the newborns windpipe.
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Ventilator (Mechanical breathing machine), to help the baby in breathing.
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Oxygen supply as long as baby is comfortably able to breathe
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Continuous positive airway pressure (CPAP), a technique by which air delivered at higher than normal pressure through the nose helps in keeping the airways open.
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Artificial surfactant: Most effective treatment if given within 6 hours of birth.
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Complications Of Disease
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Pneumothorax (air leakage into the space between the outer wall of the lungs and the chest wall).
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Pneumomediastinum (Air leakage into the space in the thorax behind the sternum and between the two lungs)
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Pneumopericardium (Air leakage into the sac surrounding the heart)
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Bleeding in the brain or lungs
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Delay in developmental milestones or mental retardation as a result of brain damage.
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Prognosis
If managed early, the survival rate of babies with HMD is more than 90%. | |
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Prevention
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Prevent preterm birth.
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Corticosteroids to mother before delivery (between 24-34 weeks of pregnancy), in those with risk of preterm delivery.
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Case Study
A 14 hour old Indian male, 2.1 kg in weight was delivered pre-term at 32 weeks gestation to a 28 year old diabetic mother by caesarean section, following rupture of membranes. During pregnancy, diabetes was under control and there was no other complication. Two hours after birth, the infant developed cyanosis and required oxygen (40%) to maintain a pink color. The respiratory distress deteriorated further over the next few hours and the infant was shifted to neonatal intensive care unit. The arterial blood gases were pH 7.31, pCO2 36, and pO2 35. He was placed on ventilator and the condition of the patient started to improve over the next few hours. | |
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References
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Crowther CA, Haslam RR, Hiller JE, et al. Neonatal respiratory distress syndrome after repeat exposure to antenatal corticosteroids: a randomised controlled trial. Lancet. June 2006; 367:1913-1919.
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Rodriguez RJ, Martin RJ, Fanaroff, AA. Respiratory distress syndrome and its management. Fanaroff and Martin (eds.) Neonatal-perinatal medicine: Diseases of the fetus and infant; 7th ed. (2002):1001-1011.
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Fanaroff AA, Stoll BJ, Wright LL, et al. Trends in Neonatal Morbidity and Mortality for Very Low Birthweight Infants. American Journal of Obstetrics and Gynecology. 2007;147:e1-e8.
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Engle WA, The Committee on Fetus and Newborn. Surfactant-Replacement Therapy for Respiratory Distress in the Preterm and Term Neonate. Pediatrics. 2008;212:419-432.
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