Tidal Volume Settings for a 28 kg Child
For a 28 kg child, the appropriate tidal volume setting should be 3-6 ml/kg predicted body weight (PBW), which translates to approximately 84-168 ml. 1
Calculation and Rationale
The most recent evidence-based guidelines from the International Journal of Surgery (2020) specifically recommend lower tidal volumes for children requiring mechanical ventilation:
- For children: Target tidal volume of 3-6 ml/kg PBW 1
- This can be increased to 5-8 ml/kg PBW in cases with well-preserved respiratory compliance 1
Using the lower range (3-6 ml/kg) for the 28 kg child:
- Minimum tidal volume: 28 kg × 3 ml/kg = 84 ml
- Maximum tidal volume: 28 kg × 6 ml/kg = 168 ml
Important Considerations
Predicted vs. Measured Body Weight
It's critical to use predicted body weight rather than measured weight when calculating tidal volumes, especially in children with abnormal BMI:
- Children with obesity have lung volumes reflecting their predicted body weight from height 2
- Children with low or normal BMI have lung volumes reflecting measured body weight 2
- Using the lower of measured and predicted body weights would provide the most lung-protective strategy 2
Plateau Pressure Limitations
When setting tidal volumes, always monitor and limit plateau pressures:
- Keep plateau pressure ≤28 cmH2O in children 1
- In restrictive lung disease, mixed disease, or congenital disorders, plateau pressure may be allowed up to 29-32 cmH2O 1
Avoiding Pulmonary Overdistention
Research has shown that tidal volumes >15 ml/kg can cause pulmonary overdistention with detrimental effects:
- Increased pulmonary vascular resistance
- Decreased cardiac output
- Worsened pulmonary vascular mechanics 3
Special Circumstances
Respiratory Compliance Considerations
- In cases with well-preserved respiratory compliance, tidal volumes may be increased to 5-8 ml/kg PBW 1
- For children with lung hypoplasia syndromes, optimal tidal volumes may be smaller than physiologic due to lower lung volumes 1
Disease-Specific Adjustments
- In restrictive lung disease, consider using higher respiratory rates to compensate for lower tidal volumes while maintaining minute ventilation 1
- In severe disease states, careful titration of PEEP is necessary alongside appropriate tidal volume settings 1
Common Pitfalls to Avoid
- Using measured weight instead of predicted body weight - This can lead to excessive tidal volumes in obese children or inadequate volumes in underweight children
- Setting tidal volumes >10 ml/kg - Guidelines strongly recommend avoiding tidal volumes >10 ml/kg ideal body weight 1
- Focusing only on tidal volume without monitoring plateau pressures - Both parameters must be considered together for lung-protective ventilation
- Neglecting to adjust settings based on respiratory mechanics - Regular reassessment of compliance and resistance is essential
By adhering to these evidence-based recommendations for tidal volume settings, you can minimize ventilator-induced lung injury while optimizing gas exchange in the pediatric patient.