Respiratory distress in the newborn

P22.9

• Description
• Diagnostic criteria
• General and supportive measures
• Medicine treatment
• Referral

DESCRIPTION

Newborn experiencing difficulty with breathing.
Causes of respiratory distress include:

Hyaline membrane disease (HMD), meconium aspiration syndrome (MAS) congenital pneumonia and transient tachypnoea of the newborn (TTN) are the most common causes of respiratory distress in newborns.

DIAGNOSTIC CRITERIA

Clinical

• Pulmonary and/or extra pulmonary disorders presenting with two or more of the following signs in a newborn baby:
  • tachypnoea (≥60 breaths/minute),
  • expiratory grunting,
  • intercostal and sternal retractions (recession), and
  • central cyanosis while breathing room air.

Investigations

• Chest X-ray to determine underlying pathology.
• Echocardiography, if available, to exclude cardiac causes of respiratory distress.
• Haematocrit, blood glucose and temperature.
• Shake test to assess risk for hyaline membrane disease:
  • Within 15 minutes after birth place 0.5 mL gastric aspirate in a clean dry test tube.
  • Add 0.5 mL of sodium chloride 0.9% and replace the cap.
  • Shake well for 15 seconds.
  • Add 1 mL 95% alcohol to the 1 mL mixture of gastric aspirate and sodium chloride 0.9%.
  • Replace cap and shake well for 15 seconds.
  • Read at 15 minutes.
    Interpretation of test:

• In positive test (very low risk of hyaline membrane dsease): surfactant use may not be indicated.

GENERAL AND SUPPORTIVE MEASURES

• Identify and treat underlying cause, e.g.:
  • Chest tube and underwater drainage of pneumothorax.
  • Isovolaemic dilutional exchange transfusion for symptomatic polycythaemia.
• Admit to neonatal high care/intensive care facility, if available.
• Handle neonate as little as possible.
• Nurse non-intubated infant in the prone position.
• Keep in a neutral thermal environment (incubator or infant crib with overhead heater). Keep room temperature, at 26–28°C, and anterior abdominal wall skin temperature at 36.2–36.8°C.
• Monitor:
  • blood pressure,
  • respiratory rate,
  • peripheral perfusion,
  • heart/pulse rate,
  • haematocrit,
  • acid-base status,
  • blood glucose,
  • body temperature,
  • blood gases,
  • SaO₂,
  • minerals and electrolytes,
  • fluid balance.
• Nutrition:
  • Provide adequate IV dextrose to maintain blood glucose ≥ 2.6 mmol/L.
  • Commence nasogastric feeding after 12–24 hours if bowel sounds are audible and meconium has been passed.
  • If enteral feeding is not possible 24 hours after birth, start IV hyperalimentation.
• Ventilation (non-invasive or invasive) is needed if:
  • An oxygen saturation of at least 90% or PaO₂ of at least 60mmHg cannot be maintained with an inspiratory oxygen concentration of ≥ 80% with or without nasal CPAP;
  • The PaCO₂ rises to > 55 mmHg with uncompensated respiratory acidosis (pH ≤ 7.20), irrespective of oxygen saturation or PaO₂ .
    (1kPa = 7.5 mmHg; 1 mmHg x 0.133 = 1 kPa)

MEDICINE TREATMENT

To eliminate central cyanosis and to maintain oxygen saturation of haemoglobin at 90–94%:

• Oxygen, warmed and humidified via head box, or nasal cannula.
  • If a pulse oximeter or facility for blood gas analysis is available oxygen, humidified via head box, or nasal cannulae to maintain oxygen tension in the blood at 60–80 mmHg.
  • If a pulse oximeter or facility for blood gas analysis is not available, regulate the inspired oxygen concentration in such a way that the least amount of oxygen that will prevent central cyanosis is used.
  • Keep PaO₂ at 60–80 mmHg and PaCO₂ at 35–45 mmHg (arterial blood gas analysis).

Nasal CPAP is needed if the neonate has a good respiratory drive with a PCO₂ of ≤ 55 mmHg but unable to maintain a SaO₂ of 90–94% on an inspiratory oxygen concentration of ≥ 60% (FᵢO₂ ) and pneumothorax has been excluded.
Administer nasal CPAP at 4–6 cm H₂O and monitor SaO₂, blood gas and acid-base status.

OR

• Oxygen/air mixture, hi-flow, warmed and humidified via nasal prongs. (Under specialist supervision)
  • Do not exceed 6 L/minute. The flow/minute (L/min) approximates the pressure generated in cm water.

Stabilise circulation and blood pressure

• Neonatal maintenance solution, IV infusion, 60–80 mL/kg/24 hours (day 1 of life) and adapt to daily maintenance requirements.
  AND/OR
  
• Sodium chloride 0.9%, 10–20 mL/kg over 1–2 hours.
  • For preterm infants restrict to 10 mL/kg.
    AND/OR
    
• Fresh Frozen Plasma, 10–20 mL/kg over 1–2 hours.
  OR
  
• Lyphilised Plasma, 10-20 mL/kg over 1-2 hours.

Inotropic support

• Dopamine, IV, 5–15 mcg/kg/minute, continued until blood pressure has stabilised.
  • Response to inotropic support will be unsatisfactory if the circulating blood volume is not corrected.

Anaemia

If anaemia is present, Hct < 40 % and Hb <13 g/dL:

• Packed red cells, IV, 10 mL/kg over 1–2 hours.

Metabolic acidosis

If pH ≤ 7.0 and the metabolic acidosis does not respond to normalisation of PaO₂, PaCO₂, blood pressure, volume expansion (hydration) and correction of anaemia:

• Sodium bicarbonate, 4.2 %, IV, administered slowly.
  • 1 mmol = 2 mL
  • HCO₃ needed (mmol) = base excess x 0.3 x body mass (kg)
  • (½ correct base deficit initially)

Polycythaemia

Treat with isovolaemic dilutional exchange transfusion using sodium chloride 0.9% if the venous haematocrit is Hct > 65%: Hb >22 g/dL and the baby is symptomatic. Perform under paediatrician’s supervision.

Hyaline membrane disease (Surfactant deficiency)

In consultation with a paediatrician.
Shake test to assess risk for hyaline membrane disease and/or x-ray chest – see above.

If surfactant deficiency is suspected or present, provide respiratory support.

• Mild surfactant deficiency: nasal CPAP 4–6 cm H[2]O.
• Moderate surfactant deficiency: “in-out” surfactant followed by nasal CPAP 4–6 cm H[2]O. Intubate infant and administer surfactant via naso-or orotracheal tube. Ventilate for a few minutes with a T-Piece Resuscitation device or resuscitation bag with a CPAP generating device. Extubate baby and put on nasal CPAP 4–6 cm H[2]O. Babies may be put on nasal CPAP directly after “in-out” surfactant administration, omitting the ventilation step following “in-out” surfactant.
• Severe surfactant deficiency: intubate baby and ventilate with a ventilator. Administer surfactant via the naso- or orotracheal tube. If a ventilator is not available the in-out surfactant followed by nasal CPAP can be used.

Short term intubation (In-out endotracheal surfactant administration)

• Nasal CPAP as required.
• If inadequate oxygenation on nasal CPAP, pre-oxygenate with bag-mask or T-piece ventilation to maintain preductal saturation between 90-94%.
• Intubate orally, give surfactant and follow with gentle manual ventilation or CPAP, as required, for 5 minutes:
  • Surfactant, 100mg/kg
• Extubate and recommence nasal CPAP.

Infection

• If infection, e.g. bronchopneumonia, is present or suspected, give antibiotics after blood cultures have been taken.
• Consider the antibiotic sensitivity profile of micro-organisms in a particular hospital when prescribing antibiotics.
  
• Aminoglycoside, e.g.:
• Gentamicin, IV, for 5-7 days in the first week of life.
  • If < 32 weeks gestation of age: 5 mg/kg/36 hours.
  • ≥ 32 weeks gestation of age: 5 mg/kg/24 hours.
  • After first week, 5 mg/kg/24 hours for all gestations.

PLUS

• Ampicillin, IV, for 5-7days.
  • If < 7 days of age: 50 mg/kg 12 hourly.
  • If 7 days – 3 weeks of age: 50 mg/kg 8 hourly.
  • If > 3 weeks of age: 50 mg/kg 6 hourly.

Review after 72 hours. If infection is confirmed or very strongly suspected continue for 10 days.
Where available, gentamicin doses should be adjusted on the basis of therapeutic drug levels.

• Trough levels (taken immediately prior to next dose), target plasma level < 1 mg/L.
• Peak levels (measured 1 hour after commencement of IV infusion or IM/IV bolus dose), target plasma level > 8 mg/L.

REFERRAL

• No improvement or deterioration despite adequate treatment.
• Development of respiratory failure and need for ventilatory support.