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Airflow distribution with manual hyperinflation as assessed through gamma camera imaging: a crossover randomised
H van Aswegen1, A van Aswegen, H Du Raan
1Department of Physiotherapy, School of Therapeutic Sciences, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa. helena.vanaswegen@wits.ac.za
Physiotherapy
|December 11, 2012
Summary
This study found no significant differences in lung airflow distribution, compliance, or hemodynamics between the Laerdal and Mapleson-C manual hyperinflation circuits. Both circuits demonstrated similar efficacy in delivering aerosolized medication during mechanical ventilation.
Area of Science:
- Respiratory Physiology
- Critical Care Medicine
- Medical Device Technology
Background:
- Manual hyperinflation (MHI) is utilized to improve lung mechanics and secretion clearance.
- The Laerdal and Mapleson-C circuits are commonly used for MHI, but their comparative effectiveness in airflow distribution is not well-established.
- Understanding differences in circuit performance is crucial for optimizing mechanical ventilation strategies.
Purpose of the Study:
- To compare airflow distribution in patients' lungs using Laerdal and Mapleson-C MHI circuits at a set positive end-expiratory pressure (PEEP).
- To evaluate differences in lung compliance and hemodynamic status between the two MHI circuits.
- To assess the impact of MHI circuits on aerosol deposition in the lungs.
Main Methods:
- A crossover randomized controlled trial was conducted in an adult multidisciplinary intensive care unit.
- Fifteen adult patients served as their own controls, receiving MHI with both Laerdal and Mapleson-C circuits on separate days.
- Technetium-99m aerosol administration and gamma camera imaging were used to assess lung deposition, alongside monitoring of heart rate, mean arterial pressure, and dynamic lung compliance.
Main Results:
- Airflow distribution, assessed by technetium-99m deposition, showed no significant differences between the Laerdal and Mapleson-C circuits.
- Greater deposition was observed in the right lung fields compared to the left, with minimal deposition in the left lower segments.
- No significant differences in dynamic lung compliance, heart rate, or mean arterial pressure were found between the two circuits.
Conclusions:
- Airflow distribution through patients' lungs is similar when using Laerdal and Mapleson-C MHI circuits with a set PEEP in the supine position.
- Both circuits appear to be equally effective in terms of lung compliance and hemodynamic stability.
- These findings suggest that circuit choice may not significantly impact aerosol delivery or patient stability during MHI.
