Question

A 10-day-old male infant weighing 950 g was scheduled for ligation of patent ductus arteriosus (PDA). He was born at 29 weeks gestation and was intubated immediately after delivery because of respiratory distress. His condition improved over the following 4 days. However, on the fifth day of his life the respiratory distress worsened and a murmur was heard over his chest. Medical treatment for PDA was attempted unsuccessfully. His blood pressure was 60/40 mm Hg, heart rate 150 beats/minute. The laboratory data were as follows: white blood cells (WBCs), 17,000/?L; hemoglobin, 11 g/dL; hematocrit, 34%; urine specific gravity, 1.005; protein 1+; sugar 1+; serum calcium 6.0 mg/dL; blood glucose, 60 mg/dL; and arterial blood gases: pH, 7.30; PaCO2, 45 mm Hg, PaO2, 60 mm Hg on FIO2 50%; inspiratory pressure, 30/4 cm H2O; and ventilation rate, 25 breaths/minute.

1. How would you classify prematurity? What are the common problems associated with prematurity?Discuss the incidence and pathophysiology of patent ductus arteriosus (PDA) in preterm infants.

2. How would you make a diagnosis of PDA? Describe its treatment.

3. How does indomethacin close the ductus? What are the adverse effects of indomethacin

Answer 1

Answer 1:

The normal gestation period in the case of humans is 40 weeks. Premature or preterm birth refers to the birth of a baby when it is born 3 weeks earlier than the normal gestation period (before 37 weeks). This is called the prematurity.

Babies that are born prematurely usually have medical complications. Prematurity may have short term or long term complications. Short term complications include problems in the first week after the birth such as breathing problems, heart problems like PDA (patent ductus arteriosus), brain problems, temperature control problems, gastrointestinal problems, blood problems, metabolism problems, and immune system problems. Long term complications include cerebral palsy, difficulty in learning, vision defects, hearing problems, dental problems, psychological problems, and chronic health issues such as asthma, feeding problems, and SIDS (sudden infant death syndrome).

PDA refers to the condition in a preterm infant in which closure of ductus arteriosus does not occur after birth. Ductus arteriosus is the blood vessel that is present in the fetus during development and connects the proximal descending aorta and trunk of the pulmonary artery. It enables most blood bypassing the non-functioning lungs fluid-filled lungs of the fetus as the blood passes from the right ventricle. When it closes at birth, it is converted into ligamentum arteriosum.

PDA leads to the unusual passage of blood to the pulmonary artery coming from the aorta or left to right shunt. It may progress to pulmonary hypertension in case it is untreated. Further, it could lead to right ventricular heart failure and cardiac arrhythmias.

Answer 2:

The diagnosis of PDA is done generally by non-invasive techniques including Echocardiography and related Doppler studies.

Treatment of PDA: Neonates sans any adverse symptoms that may be referred to as outpatients. The neonates having symptoms of PDA can be treated with non-surgical and surgical methods. Non-surgical methods include the closure of ductus arteriosus (DA) by minimally invasive transcatheter PDA closure. Surgical methods include DA closure using ligation, tying manually, or through intravascular coils or plug that forms a thrombus in ductus arteriosus.

Answer 3:
Indomethacin administration is sufficient for the closure of DA. It inhibits prostaglandin E₂. Prostaglandin E₂ is released by DA as well as the placenta and has a major role in the opening of DA. Hence, inhibiting it can cause the closure of DA. Indomethacin’s adverse effects include gastrointestinal (GI) dysfunctioning such as GI bleeding, abdominal distension, necrotizing enterocolitis, gastric ulceration and gastric perforation, and platelet dysfunction and the tendency of bleeding.