Submitted on December 13, 2006
Accepted on August 13, 2007
Oscillatory Pressure Wave Transmission from the Upper Airway to the Carotid Artery
Lauren Howitt1, Kristina Kairaitis2*, Jason P Kirkness2, Sarah R Garlick1, John R Wheatley2, Karen Byth3, and Terence Amis2
1 Ludwig Engel Centre for Respiratory Research, Westmead Millenium Institute, Westmead, New South Wales, Australia
2 Ludwig Engel Centre for Respiratory Research, Westmead Millenium Institute, Westmead, New South Wales, Australia; University of Sydney, Westmead, New South Wales, Australia
3 Westmead Milleniuum Institute, Westmead, New South Wales, Australia
* To whom correspondence should be addressed. E-mail: kristina_kairaitis{at}wmi.usyd.edu.au.
Snoring associated vibration energy transmission from the upper airway to the carotid artery has been hypothesized as a potential atherosclerotic plaque initiating/rupturing event that may provide a pathogenic mechanism linking snoring and embolic stroke. We examined transmission of oscillatory pressure waves from the pharyngeal lumen to the common carotid artery wall and lumen in seven male, anesthetised, spontaneously breathing New Zealand White rabbits. Airflow was monitored via a pneumotachograph inserted in series in the intact trachea. Fifteen-20 second runs of, separately, 40, 60, and 90 Hz oscillatory pressure waves (PTamp, amplitude 2-20cmH2O) were generated by a loudspeaker driven by a sine wave generator and amplifier and superimposed on tidal breathing via the cranial tracheal connector. Pressure transducer tipped catheters measured pressure amplitudes in the tissues adjacent to the common carotid artery bifurcation (PCTamp) and within the lumen (carotid sinus; PCSamp). Data were analysed using power spectrum analysis and linear mixed effects statistical modelling. Both the frequency (f) and amplitude of the injected pressure wave influenced PCTamp and PCSamp in that lnPCTamp=1.2(PTamp)+0.02(f)-5.2, and lnPCSamp=0.6(PTamp)+0.02(f)-4.9 (both p<0.05). Across all frequencies tested, transfer of oscillatory pressure across the carotid artery wall was associated with an amplitude gain as expressed by a PCSamp/PCTamp ratio of 1.8±0.3 (n=6). Our findings confirm transmission of oscillatory pressure waves from the upper airway lumen to the peri-pharyngeal tissues and across the carotid artery wall to the lumen. Further studies are required to establish the role of this incident energy in the pathogenesis of carotid artery vascular disease.
