Salbutamol Dosing for Nebulisation: Asthma vs Hyperkalemia
For Acute Asthma Exacerbations
In acute severe asthma, nebulised salbutamol 5 mg (or 0.15 mg/kg in children) should be administered initially and repeated every 15-30 minutes for the first hour if needed, then every 4-6 hours as the patient improves. 1
Adults - Initial Dosing
- Salbutamol 5 mg via oxygen-driven nebuliser for acute severe asthma 1
- Repeat every 15-30 minutes if patient is not improving after initial dose 1
- Once improving, continue 4-6 hourly until PEF >75% predicted 1
- Add ipratropium bromide 500 µg if poor response to initial salbutamol 1
Children - Weight-Based Dosing
- Salbutamol 5 mg (or 0.15 mg/kg) via oxygen-driven nebuliser 1
- For very young children, use half doses 1
- Repeat every 30 minutes up to 3 doses in first hour if not improving 1
- Once improving, continue 1-4 hourly, then space to 4 hourly 1
- Add ipratropium 250 µg (not 100 µg as some sources state) if inadequate response 1
Duration of Treatment
- Continue frequent nebulisation until PEF >75% predicted and diurnal variability <25% 1
- Typically requires 24-48 hours of regular nebulisation before switching to MDI 1
- Do not discharge until patient has been stable on discharge medication for 24 hours 1
Critical Pitfall
Avoid inadequate dosing: Emergency management requires up to 10-20 puffs via MDI with spacer (equivalent to nebulised dose), not the 2 puffs used at home 2. The British Thoracic Society emphasizes that 2 puffs taken at home are insufficient for acute episodes 2.
For Hyperkalemia Treatment
For hyperkalemia, salbutamol 10-20 mg nebulised over 15 minutes produces maximal potassium reduction of 1.18-1.29 mmol/L at 90-120 minutes, or alternatively 5 µg/kg IV over 15 minutes can be used with similar efficacy and minimal side effects. 3, 4
Nebulised Route (Preferred for Safety)
- 10 mg nebulised produces peak effect at 120 minutes (mean reduction 1.29 mmol/L) 4
- 20 mg nebulised produces peak effect at 90 minutes (mean reduction 1.18 mmol/L) 4
- Effect lasts at least 120 minutes 3
- Single dose is typically sufficient; repeat dosing not well-studied 3, 4
Intravenous Route (Alternative)
- 5 µg/kg IV over 15 minutes in children produces significant reduction (mean 1.4-1.6 mmol/L) 3
- Serum potassium decreases significantly within 30 minutes and continues to 120 minutes 3
- Initially used dose of 0.5 mg IV caused excessive tachycardia, especially in children—avoid this dose 5
- Lower dose of 4 µg/kg produces adequate effect without side effects, even in newborns 5
Duration and Monitoring
- Single administration is the standard approach 3, 4
- Monitor serum potassium at 30,60, and 120 minutes post-administration 3
- Effect is temporary—address underlying cause and consider definitive therapy (dialysis, potassium binders) 4
- May reverse hyperkalemia without further intervention in some patients 3
Comparative Efficacy
- Salbutamol produces similar effect to insulin-dextrose but is more effective than bicarbonate at 60 minutes 4
- IV and nebulised routes produce comparable effects 4
Key Differences Between Indications
| Parameter | Acute Asthma | Hyperkalemia |
|---|---|---|
| Dose | 5 mg (adults/children) [1] | 10-20 mg nebulised or 5 µg/kg IV [3,4] |
| Frequency | Every 15-30 min initially, then 4-6 hourly [1] | Single dose [3,4] |
| Duration | 24-48 hours until PEF >75% [1] | Single treatment (effect lasts 120 min) [3] |
| Route | Oxygen-driven nebuliser preferred [1] | Nebulised or IV equally effective [4] |
| Monitoring | PEF every 15-30 min, SpO₂ >92% [1,2] | Serum K⁺ at 30,60,120 min [3] |
Common Pitfall Across Both Indications
The hyperkalemia dose (10-20 mg) is 2-4 times higher than the asthma dose (5 mg) 1, 4. Using asthma dosing for hyperkalemia will produce suboptimal potassium reduction. Conversely, using hyperkalemia dosing for asthma provides no additional bronchodilator benefit and increases side effects unnecessarily.