Salbutamol
Salbutamol solution for the treatment of infants in the Neonatal Intensive Care Unit
Dose and Administration
Salbutamol solution for nebulization is available in PICU or ED, the intravenous preparation is available in NICU.
For Bronchospasm in infants with bronchopulmonary dysplasia (BPD):
Term or post term infants: follow the Starship asthma guideline.
For Hyperkalaemia:
intravenous: 4 micrograms/kg IV over 10 minutes.¹
nebulized endotracheal: 400 microgram 2 hrly, maximum 12 doses.²
Indications
Bronchospasm in infants with bronchopulmonary dysplasia.
Emergency treatment of hyperkalaemia.
Contraindications and precautions
Known sensitivity to salbutamol and/or propellant mixture.
Caution in infants with hypertension, hyperthyroidism, hypokalaemia.
Concurrent use of β blocking agents.
Mechanism of action
The mechanism of action of salbutamol is not yet completely understood. Salbutamol binds the β2 adrenoceptor with relatively low affinity but moderate efficacy and behaves largely as an agonist. It has a relatively short half-life due to rapid re-equilibration of the drug at the active site with limited residency time. β2 adrenoceptor activation leads to an increase of intracellular cAMP and activation of protein kinase A leading to smooth muscle relaxation. Protein kinase A also activates the Na / K ATPase, facilitating transport of K+ across the cell membrane into the cell and stabilization of the membrane potential.³,⁴
Administration and metabolism
Less than 5% of aerosol particles reach the lung if given via face mask or endotracheal tube, respectively.⁵⁻⁷ Some proportion of the aerosol may be swallowed and readily absorbed from the gastrointestinal tract. First pass metabolism of salbutamol occurs in the liver. About half is excreted in the urine as an inactive sulphate conjugate, and about 30% is excreted as unchanged salbutamol.
Bronchodilatation usually starts within 3-5 minutes with peak at 15-20 minutes. The duration of effect is approximately 4 hours.
Clinical effect
Studies suggest that in ventilator dependent preterm infants, salbutamol nebulization facilitated a short lasting decrease in respiratory system resistance and an improvement in respiratory system compliance. However, salbutamol does not seem to be effective in preventing long term sequelae such as BPD and/or death.⁸
Side effects
Reduced airway tone causing ventilation/perfusion mismatch.
Tachycardia
Hypokalaemia
Irritability, tremor, hyperactivity
Vomiting, food intolerance
Lactic acidosis - rare, described in adults
Administration of Nebulised Salbutamol
Description
Clear, colourless respirator solution 1 mg/ml in 2.5 ml sterinebs. Always make up to a total of 2 ml with normal saline. Be aware: salbutamol comes in two different preparations:
for IV administration (available in NICU)
and as sterinebs (available from ED or PICU):
They are not interchangeable
Prescription
Salbutamol respirator solution is charted on prescription chart in mg/dose.
The order states the amount of salbutamol and the amount of normal saline, make up to a total of 2 ml. Nebulise until empty or spluttering: maximum time 10 minutes.
Administration
Nebulised via face mask
Ensure nebuliser is in working order.
Salbutamol is diluted in normal saline. Make up to 2 ml.
Use a mask with large side holes - not small ones, to avoid CO2 build up.
Neb
Nebulised via endotracheal tube - Babylog 8000/VN500
Use a pre-packaged ventilator nebuliser kit (Fisher and Paykel).
Fill the nebulizer with the appropriate solution.
Connect the nebulizer hose to a flow meter. Set the flow at 6 L/min and make sure mist is generated.
Turn VG off and remove the flow sensor from the breathing circuit. Set the ventilator flow to 4 L/min.
After the ventilator flow was set to 4 L/min, insert the nebulizer where the flow sensor has been (between the Y-piece of the breathing circuit and the endotracheal tube). See photo below
Nebulise until dry or spluttering: maximum 10 minutes. Tap nebuliser occasionally to release solution into the reservoir.
Remove the nebulizer after 10 min or when dry, reinsert the flow sensor and return to your pre-nebulization ventilator settings.
Observation and documentation
Cardiorespiratory and SaO2 monitoring is necessary during and up to 30 minutes after nebulization.
If heart rate is >180/min withhold medication and notify doctor / NS-ANP immediately.
Ensure ventilator pressures remain unchanged during nebulisation.
Document patient response to therapy.
Consider K+ monitoring