1. Beginning Inspiration
Overnight Pharyngeal Narrowing in Patients with Congestive Heart Failure and Sleep Disordered Breathing
Tom Carlisle,3 Abdul Ghani Sankri-Tarbichi,1,2 Amy Bascom,1,2 Mark Pohlman,1,2 Mary J Morrell3 and Safwan Badr.1,2
1John D. Dingell Veterans Affairs Medical Center, Detroit, MI; 2Wayne State University, Detroit, MI; 3National Heart and Lung Institute, Imperial College London, UK.
Patient numbers
MC = 1
TP = 2
DC = 3
DL = 4
Figure 1. Pharyngeal cross-sectional area at start and end of night
INTRODUCTION
The prevalence of sleep disordered breathing (SDB) in congestive heart failure (CHF) is higher than in the general population (approximately 50% vs. approximately 3% respectively)(1,2). Despite this, the mechanisms of SDB in CHF are not well understood. Extra-luminal pressure may be an important factor due to increased fluid retention and nocturnal fluid shift from the lower extremities to the neck(3).
Start of night
End of night
Beginning Inspiration
Peak Inspiration
End Inspiration/
Beginning Expiration
Peak Expiration
End Expiration
Original images of pharyngeal lumen taken from Patient 2. The pharyngeal cross-sectional area at the start of the night (top panel) was approximately 5 times greater than at the end of the night (bottom panel).
AIM
To test the hypothesis that sleeping supine is associated with decreased pharyngeal cross-sectional area and increased neck circumference from the start to the end of the night, in CHF patients with SDB.
METHODS
Polysomnography was carried out in all patients, including supraglottic pressure, airflow and mask pressure. The retropalatal pharyngeal lumen was visualised using a fibreoptic bronchoscope(4,5); neck circumference was measured while awake and supine at the start and end of the night.
Patients slept supine with a nasal mask connected to a CPAP machine set at 2 cmH2O.
Images of the pharyngeal lumen and supraglottic pressure were obtained over 5 respiratory cycles during NREM sleep as close to the start and end of the night as possible.
Retropalatal cross-sectional area was measured using image analysis software; an index of inspiratory and expiratory pharyngeal compliance was calculated as ∆cross-sectional area/∆supraglottic pressure(6).
Figure 2. Overnight changes in pharyngeal cross-sectional area and neck circumference
Table 1. Patient Demographics
Patient Number 1 2 3 4
Gender F M
Age (years) 41 37 44 35
BMI (kg/m2)
39.9
26.4
47.8
34.2
LVEF (%) 20 45 5
AHI (events/hr)
31.8
16.0
46.4
41.2
CAI (events/hr)
11.5
1.3
9.0
20.4
OAI (events/hr)
0.3
0.0
5.3
0.8
HI (events/hr)
20.0
14.7
32.1
Pharyngeal cross-sectional area decreased overnight in all 4 patients (A) while neck circumference increased overnight in 3 out of 4 patients (B).
CONCLUSIONS
Sleep was associated with overnight pharyngeal narrowing and increased neck circumference in CHF patients with SDB.
Our preliminary findings corroborate the suggestion that fluid shift towards the neck during the night may be an underlying mechanism of SDB in CHF.
Further research is needed to investigate whether these data are supported by overnight changes in pharyngeal collapsibility.
RESULTS
Four CHF patients were studied (see Table 1 for demographics). Pharyngeal cross-sectional area decreased overnight in all patients, and at all phases of the respiratory cycle (Fig 1 & Fig 2A), and neck circumference increased in 3 out of 4 patients (Fig 2B). Pharyngeal compliance decreased overnight (start of night: 3.2 (-0.03, 6.56) mm2/cmH2O vs. end of night: 0.7 (-0.03, 3.02) mm2/cmH2O).
REFERENCES
ACKNOWLEDGEMENTS
This project was funded by a VA Merit Award, the NIH and the National Heart and Lung Institute Foundation. It was also supported by the NIHR Respiratory Disease Biomedical Research Unit at the Royal Brompton and Harefield NHS Foundation Trust, the John D. Dingell Veterans Affairs Hospital, Wayne State University and Imperial College London.
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