Case Study: The Premature Baby - Week 5

Case Presentation

Patient: Baby Girl Martinez
Gestational Age: 28 weeks (born 12 weeks premature)
Birth Weight: 1,120 grams
Delivery: Emergency cesarean section due to maternal preeclampsia

Baby Martinez was born prematurely at 28 weeks gestation. At delivery, she required brief positive pressure ventilation. She is now 4 hours old and showing signs of respiratory distress. She has been transferred to the neonatal intensive care unit (NICU) for ongoing management.

Physical Examination

Respiratory: Respiratory rate 72/min, moderate subcostal and intercostal retractions, nasal flaring, expiratory grunting
Auscultation: Poor air entry bilaterally, diffuse fine crackles
Skin: Pink centrally, mild acrocyanosis, gelatinous appearance
General: Appropriate size for gestational age, active, primitive reflexes present

Investigations

Chest X-ray: Diffuse ground-glass appearance with air bronchograms

Blood Gas:

Parameter	Value	Normal
pH	7.28	7.35-7.45
pCO2	52 mmHg	35-45
pO2	48 mmHg	60-80
HCO3-	22 mmol/L	22-26

Clinical Reasoning Questions

1. What is the most likely diagnosis for Baby Martinez?

Congenital pneumonia Transient tachypnea of the newborn Respiratory Distress Syndrome (RDS) Meconium aspiration syndrome

Correct! Respiratory Distress Syndrome (RDS)

RDS is the most common cause of respiratory distress in premature infants. The classic triad is:
• Prematurity (28 weeks)
• Clinical signs: grunting, retractions, nasal flaring, tachypnea
• Chest X-ray: ground-glass appearance with air bronchograms
The pathophysiology is surfactant deficiency, leading to alveolar collapse and poor gas exchange.

2. What bioscience principle explains why premature infants lack adequate surfactant?

Surfactant production is stimulated by estrogen at term Type II pneumocytes begin producing surfactant around 24-28 weeks, with peak at 35 weeks Surfactant is only produced after the first breath Premature infants break down surfactant faster than term infants

Correct! Type II pneumocytes develop surfactant production gradually

Surfactant is produced by Type II alveolar cells (pneumocytes). Production begins at 24-28 weeks gestation but is minimal at this stage. Adequate surfactant stores are not present until approximately 35 weeks gestation. This infant at 28 weeks has insufficient surfactant to prevent alveolar collapse. Corticosteroids given to mother before preterm delivery can accelerate fetal lung maturation.

3. What is the primary function of pulmonary surfactant?

Reduce surface tension in alveoli to prevent collapse Increase oxygen binding to hemoglobin Stimulate respiratory drive in the medulla Filter pathogens from inspired air

Correct! Reduce surface tension in alveoli

Surfactant is a lipoprotein complex (dipalmitoylphosphatidylcholine is the main component) that lines the alveoli. It reduces surface tension, which:
• Prevents alveolar collapse at end-expiration
• Reduces the work of breathing (compliance)
• Maintains alveolar stability
Without surfactant, surface tension causes alveolar collapse, requiring much higher pressures to reopen them, leading to atelectasis and respiratory failure.

Bioscience Integration

Lung Development Stages

Embryonic (4-7 weeks): Lung buds form
Pseudoglandular (5-17 weeks): Branching of airways
Canalicular (16-25 weeks): Respiratory bronchioles develop, gas exchange possible
Saccular (24 weeks-birth): Terminal sacs form, surfactant begins production
Alveolar (36 weeks-8 years): Alveoli multiply, mature surfactant system

At 28 weeks, Baby Martinez is in the saccular stage with immature, few alveoli and inadequate surfactant.

Nursing Implications

Respiratory support: CPAP or mechanical ventilation with PEEP
Surfactant replacement: Intratracheal administration of exogenous surfactant
Monitoring: Continuous SpO2, blood gases, work of breathing
Minimize stimulation: Cluster care, reduce energy expenditure
Thermoregulation: Incubator care to reduce oxygen demands

The Premature Baby

Learning Objectives