Abstract
Whole body plethysmography (WBP) monitors respiratory rate and depth but conventional analysis fails to capture the diversity of waveforms. Our first purpose was to develop a waveform cluster analysis method for quantifying dynamic changes in respiratory waveforms. WBP data, from adult Sprague-Dawley rats, were sorted into time domains and principle component analysis was used for hierarchical clustering. The clustering method effectively sorted waveforms into categories including sniffing, tidal breaths of varying duration, and augmented breaths (sighs). We next used this clustering method to quantify breathing after opioid (fentanyl) overdose and treatment with ampakine CX1942, an allosteric modulator of AMPA receptors. Fentanyl caused the expected decrease in breathing, but our cluster analysis revealed changes in the temporal appearance of inspiratory efforts. Ampakine CX1942 treatment shifted respiratory waveforms toward baseline values. We conclude that this method allows for rapid assessment of breathing patterns across extended data recordings. Expanding analyses to include larger portions of recorded WBP data may provide insight on how breathing is affected by disease or therapy.
Highlights
Whole body plethysmography (WBP) chambers enable collection of waveform data corresponding to breathing as well as related behaviors such as sighing or sniffing
Once tidal volume was reduced to 50% of baseline values, either ampakine CX1942 or saline vehicle were injected intravenously
Principle Component Analysis Allows for Rapid Classification of Respiratory Waveforms
Summary
Whole body plethysmography (WBP) chambers enable collection of waveform data corresponding to breathing as well as related behaviors such as sighing or sniffing. The respiratory-related waveforms recorded using WBP in awake animals are dynamically changing. Further additional factors such as posture (Freedman, 1979), airway resistance (Lofgren et al, 2006), thoracic cavity stiffness, vagal feedback (Sammon and Bruce, 1991; Del Negro et al, 2002), temperature, humidity, and body movement can affect respiratory airflow measured with a WBP. Due to variability in WBP waveforms, large portions of the recording periods are usually omitted from WBP waveform analysis in favor of arbitrarily defined periods of baseline or “stable breathing.”. Analysis of these periods are usually limited to assessment of inspiratory tidal volume (VT) and respiratory rate Due to variability in WBP waveforms, large portions of the recording periods are usually omitted from WBP waveform analysis in favor of arbitrarily defined periods of baseline or “stable breathing.” Analysis of these periods are usually limited to assessment of inspiratory tidal volume (VT) and respiratory rate
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