Apnoea and hypoglycaemia in a 36-week infant at 28 hours
A 36+1-week female, birth weight 2,410 g (appropriate for gestational age), is admitted to a level II special-care nursery after an uncomplicated vaginal delivery to a 29-year-old mother treated with magnesium sulfate for pre-eclampsia. Cord gas: pH 7.31, base deficit 4 mmol/L. At 28 hours the nurse reports three self-resolving pauses in breathing lasting 18-22 seconds, each followed by bradycardia to 88/min, and a capillary glucose of 34 mg/dL (1.9 mmol/L). Temperature is 36.1 °C, respiratory rate 62/min, and the infant has taken only 18 mL of expressed breast milk over the last three feeds. She is jaundiced to the nipples, transcutaneous bilirubin 12.4 mg/dL, and the capillary haematocrit is 65%. Capillary refill is 3 seconds and the abdomen is soft. The level II nursery has no resident paediatrician overnight; the on-call doctor covers three hospitals by telephone. The parents ask whether the baby can simply be observed until the morning ward round.
1. List, in priority order, the problems you would act on in the next 60 minutes, and justify each action using the numbers given.
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1. Hypoglycaemia (34 mg/dL at 28 h) - below the 45 mg/dL treatment threshold at this age, and it is a plausible cause of the apnoeas. Give 10% dextrose 2 mL/kg IV push, then an infusion delivering 6-8 mg/kg/min; recheck glucose in 30 minutes. Do not try to correct this with enteral feed alone, because she is tachypnoeic at 62/min and already feeding poorly.
2. Polycythaemia - capillary haematocrit 65% with symptoms (apnoea, hypoglycaemia, poor perfusion) is in the range where partial exchange transfusion is considered. Send a venous sample to confirm before acting; polycythaemia both causes hypoglycaemia (consumption of glucose by increased red cell mass) and predisposes to apnoea and necrotising enterocolitis.
3. Apnoea with bradycardia at 28 h - in a 36-week infant apnoea of prematurity is possible, but onset after 24 h mandates a search for secondary causes: sepsis, hypoglycaemia, hypothermia (36.1 °C), polycythaemia, seizures, electrolyte disturbance, and maternal magnesium effect. Check magnesium if there was a therapeutic level at delivery.
4. Presumed sepsis - apnoea plus temperature instability plus poor feeding is a red flag. Blood culture and CRP, and empirical ampicillin plus gentamicin within 1 hour. Lumbar puncture should be done if the infant is stable enough, but must never delay antibiotics.
5. Jaundice (12.4 mg/dL at 28 h) - this is above the phototherapy threshold for 36 weeks at this age; start phototherapy now, send total and direct bilirubin, blood group and direct antiglobulin test.
6. Thermoregulation and feeding - incubator or skin-to-skin to normothermia, IV maintenance fluids, and withhold oral feeds until respiratory rate falls below 60/min and glucose is stable.
2. The mother asks whether the apnoeas mean her daughter has brain damage. How do you explain apnoea of prematurity versus secondary apnoea, and what would you tell her about caffeine and about discharge?
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Explain that at 36 weeks the respiratory control centre is still immature, and brief pauses of 5-10 seconds are common; 18-22 seconds with a drop in heart rate is longer than expected and needs investigation rather than reassurance. Distinguish two categories for her:
- Primary (apnoea of prematurity): immature brainstem control, worse during active sleep and after feeds, no other signs, responds to caffeine and time.
- Secondary: the pause is a symptom of something else - infection, low sugar, polycythaemia, low temperature, seizures, or a structural airway problem. In this infant we already have three candidate secondary causes (glucose 34 mg/dL, haematocrit 65%, temperature 36.1 °C), so the apnoeas do not automatically imply a brain injury; they imply we must treat what we find.
On prognosis, be honest but non-alarming: a small number of brief, self-resolving events in a 36-week infant, with an identified and corrected cause, carry a good outlook. Risk rises with recurrent events, need for positive-pressure ventilation, seizures or abnormal neurology, none of which she has yet.
Caffeine citrate: load 20 mg/kg, then 5-10 mg/kg once daily, if events recur or the infant needs stimulation. It reduces apnoea and extubation failure; side effects are tachycardia and feed intolerance.
Discharge criteria to state explicitly: no apnoea or bradycardia for 5-8 days off caffeine, established oral feeding with weight gain, temperature stable in an open cot, a passed car-seat challenge, and a documented plan for who checks the baby and when.
3. The receiving hospital asks whether a lumbar puncture must be done before antibiotics, given that transfer is not planned. How do you decide, and how do you document it?
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Reasoning: the infant has a clinical sepsis syndrome (apnoea, temperature instability, poor feeding, hypoglycaemia) at 28 hours, which is the peak age for early-onset group B streptococcal disease. In early-onset sepsis, meningitis coexists in roughly 10-15% of bacteraemic infants, and missing it changes antibiotic duration and drug choice (meningitic doses of ampicillin and gentamicin, or a third-generation cephalosporin).
Decision rule to apply:
- Do the LP first if the infant is cardiorespiratory stable: no need for ventilation, no shock, no coagulopathy, no thrombocytopenia below 50 x 10^9/L, and the procedure can be done by an experienced operator within minutes.
- Defer the LP if there is instability, and give antibiotics immediately; document the deferral and the plan to perform it once the glucose, temperature and breathing are controlled, ideally within 24-48 hours and before antibiotics are stopped.
- Never delay antibiotics for the LP; the time target is 1 hour from recognition.
Practical points: take the blood culture before the first dose if a vein is already accessed, but do not spend 20 minutes hunting for a vein; obtain a full blood count, CRP and glucose at the same time; and correct the glucose before the LP so the cerebrospinal fluid glucose is interpretable.
Documentation should record the indication, the contraindication to immediate LP if deferred, the time of the first antibiotic dose, the time of the blood culture, and the named clinician who will do the LP and when. Also record the telephone discussion with the on-call consultant, since the nursery has no resident doctor overnight.