What is the recommended target blood pressure (systolic/diastolic in mmHg) for a 7-day-old preterm infant born at 28 weeks gestation?

Explanation

## Blood Pressure Targets in Preterm Neonates ### Gestational Age and Postnatal Age Considerations **Key Point:** Blood pressure in preterm infants depends on both gestational age at birth and postnatal age. Systolic BP increases approximately 1–2 mmHg per week of gestation and 1–2 mmHg per day of postnatal life. ### Mean Blood Pressure Formula for Preterm Infants A practical bedside rule: $$\text{Mean BP (mmHg)} \approx \text{Gestational age (weeks)} + \text{Postnatal age (days)}$$ For a 28-week infant at 7 days of life: - Mean BP ≈ 28 + 7 = 35 mmHg - Systolic BP ≈ Mean + 15 = ~50 mmHg - Diastolic BP ≈ Mean − 15 = ~20 mmHg **However**, the more commonly cited target for a 28-week infant at day 7 is **50–60 / 30–40 mmHg**, accounting for the natural rise in BP with postnatal maturation. ### Blood Pressure Norms by Gestational Age and Postnatal Day | Gestational Age | Postnatal Day 1 | Postnatal Day 7 | Postnatal Day 28 | |-----------------|-----------------|-----------------|------------------| | **24 weeks** | 35–45 / 15–25 | 40–50 / 20–30 | 50–60 / 30–40 | | **28 weeks** | 40–50 / 20–30 | **50–60 / 30–40** | 55–65 / 35–45 | | **32 weeks** | 45–55 / 25–35 | 55–65 / 35–45 | 60–70 / 40–50 | | **36 weeks** | 50–60 / 30–40 | 60–70 / 40–50 | 65–75 / 45–55 | **High-Yield:** Hypotension in preterm infants (systolic <30 mmHg in extremely preterm, <40 mmHg in moderately preterm) is associated with intraventricular hemorrhage (IVH), periventricular leukomalacia (PVL), and necrotizing enterocolitis (NEC). Treatment includes fluid bolus, inotropes (dopamine, dobutamine), and hydrocortisone in catecholamine-resistant hypotension. **Clinical Pearl:** Blood pressure should be measured in the right arm (upper extremity) to avoid ductal shunting effects. Oscillometric devices are preferred over manual auscultation in preterm infants due to difficulty hearing Korotkoff sounds. **Mnemonic:** **GA + PNA = Mean BP** (Gestational Age in weeks + Postnatal Age in days ≈ Mean BP in mmHg). Systolic is roughly Mean + 15; Diastolic is roughly Mean − 15. [cite:Nelson Textbook of Pediatrics 21e Ch 94]