1. The Coordination of Breathing and Swallowing in Healthy Subjects Across Seven Decades
Matt Buzek, B.S., Jenna Thompson, B.S., Victoria McKenna, M.S., CCC-SLP, Lisa Kelchner, Ph.D, CCC-SLP, BCS-S
College of Allied Health Sciences - Communication Sciences and Disorders
Coordination between respiration and swallowing is vital to
nutrition, airway protection, and pulmonary health.1-15 The
purpose of this investigation was to advance the
understanding of how respiratory-swallow patterns vary
across age and consistencies. Outcomes will provide
insight on swallowing stability across the lifespan and benefit
future research that aims to compare data from healthy
individuals to those with dysphagia.
Introduction
• As children grow and mature, there is an improved
coordination of feeding and swallowing.7 A majority of
healthy adults have been observed to have an E-E RP.2,3
However, it is unknown how stable the E-E pattern is
across the lifespan. This study aims to examine
respiratory patterns over time.
• Duration of apneic pause (DAP) in healthy adults has
been observed to be similar across bolus viscosities, and
increased with larger boluses.4,5 Thin liquid swallows in
infants are on average 0.6 seconds, while they reach 1
second in healthy adults.13 Therefore, DAP may vary over
time as well, depending on the oral-motor development of
childhood, and increasing age.
Background
Participants:
• A total of thirteen individuals (9 females and 4 males)
participated with an age range of 4-68 years (Median =
31, SD = 21.98339). The data were acquired from a
larger study ongoing in the Voice and Dysphagia Lab at
the University of Cincinnati.
• All participants were healthy with typical development
and no history of swallowing problems. Exclusion
criteria included prior history of dysphagia,
developmental delay, speech and language disorders or
delay, structural disorders, or neurological disorders.
• Duration of apneic pause (DAP) is a brief cessation of
respiration that occurs as a food or liquid passes through
the pharynx during a swallow.12 It is measured in seconds.
• Respiratory phase (RP) surrounding the swallowing
events, which are identified to be inspiratory or expiratory
in nature.1-15 Major RP patterns include Expiration-
Swallow-Expiration (EE), Inspiration-Swallow-Expiration
(IE), Expiration-Swallow-Inspiration (EI), and Inspiration-
Swallow-Expiration (IE).
Definitions
• Post hoc analyses revealed significant differences in DAP
between dry and puree swallows. The researchers
speculate that this discrepancy may be caused by the
difference between a volitional and non-volitional swallow. A
dry swallow is a more volitional act that occurs when the
participant is told to swallow. In a sense, a dry swallow
requires more ‘ preparatory thought’ and intentional
muscular effort, thus explaining the longer DAP. On the
other hand, when presented with puree, the swallow is more
of a natural reaction that the body is accustomed to making
in healthy, sensate individuals. Thus, the puree swallow may
be more timely, resulting in a shorter DAP.
• The effect of age on DAP of thin liquid swallows was also
analyzed. Once determined that age and DAP are not
linearly related, a quadratic regression model was found to
be significant. Of note, DAP was found to be more stable in
participants between ages 20-50, and more variable in
participants ages 4-10 and 50-70. It is suspected this
relationship is indicative of swallow stability changes in
younger and older populations. In younger children, the
swallowing-breathing mechanism is still maturing and
developing, which may lead to variability in the DAP across
participants. Similarly, older adults undergo physiological
changes with typical aging that may explain the variability of
DAP in those populations.4
• Expiration-expiration was the most common RP pattern
across all participants, at 72%. This is consistent with prior
data discovered in other studies.2,3 The next most common
pattern was inspiration-expiration at 14%. Thus, 86% of all
swallows in this study were followed by expiration. It is
suspected that the RP is more stable across the lifespan
and develops earlier in order to prevent inhalation after the
swallow.
DiscussionMethods
Procedure:
• Participants were seated for the duration of the study.
• An oral mechanism examination was completed to
assess anatomy/physiology to verify a healthy
swallow.
• Participants were then asked to complete the following
protocol to garner natural swallows:
1) Swallow your saliva five times
2) Swallow five sips of 5ml of water
3) Swallow five teaspoon sized bites of applesauce
Results
Duration of Apneic Pause Respiratory Phase
Results Section
Buzek & Thompson
Duration of Apneic Pause:
Duration of Apneic Pause Summary Statistics
Bolus Type Mean Median SD
Dry 1.777 1.875 0.948779
Thin 1.2574 0.7496 1.034645
Puree 0.8384 0.8931 0.362242
Box Plot: Duration of Apneic Pause by Bolus Consistency
· The data did not meet the assumptions of normality or homoscedasticity; thus, a
non-parametric test was chosen. A Kruskall-Wallis one-way analysis of variance
revealed significant group differences for duration of apneic pause across bolus
consistency (H = 8.9479, df = 2, p-value = 0.0114). !
· Post hoc pairwise comparison with a Wilcoxon Signed-Rank test for dependent
groups revealed a significant difference between puree and dry swallows (p =
0.00024). !
!
Bolus Consistency
DurationofApneic
Pause(seconds)
• The box plot above shows that the data do not meet the
assumptions of normality or homoscedasticity; thus, a
non-parametric test was chosen. A Kruskall-Wallis one-
way analysis of variance revealed significant group
differences for duration of apneic pause across bolus
consistency (H = 8.9479, df = 2, p = .0114).
• Post hoc pairwise comparison with a Wilcoxon Signed-
Rank test for dependent groups revealed a significant
difference for DAP between puree and dry swallows (p =
.00024). Bonferroni Correction p value < .017 then the
relationship is significant.
Post Hoc Comparisons using the Wilcoxon Signed-Rank Test
p-value
Dry vs Thin 0.06812
Thin vs Puree 0.09424
Dry vs Puree 0.00024
!
Bonferroni Correction p-value < .017 then the relationship is significant. ** Add in
speculations in our discussion section
Linear Regression Model of DAP and Age with a Thin Liquid Consistency
!
Graph Explanation: Figure _: A simple linear regression model of Age vs DAP with a
line of best fit ( DAP’ = 0.7255 + 0.01635*Age).
· A simple linear regression model revealed that age was not a significant predictor
of DAP length (p = 0.245) and that the model was not significant ( p = 0.2449,
with R2
= .1206).
Age
DurationofApneic
Pause(inseconds)
Quadratic Regression Model of DAP and Age with a Thin Liquid Consistency
Explanation: Fig _: A quadratic regression model with Age and DAP ( DAP’ = 2.12789
– 0.1141*Age + 0.00189 *Age2
)
· A quadratic regression model revealed that Age and Age2
were both significant
predictors ( p = 0.00974, and p = 0.00372, respectively). The model was also
significant ( p = 0.006408, and Adjusted R2
= .563). The relationship is deemed
a moderate quadratic relationship.
Age
DurationofApneic
Pause(inseconds)
Duration of Apneic Pause: Liquid Swallows
• A simple linear regression model revealed that age was not
a significant predictor of DAP length (p = .245) and that the
model was not significant ( p = .2449, with R2 = .1206).
• Figure 2 represents a quadratic regression model of age
and DAP revealed that Age and Age2 were both significant
predictors ( p = .00974, and p = .00372, respectively). The
model was also significant (p = .006408, and Adjusted R2 =
.563). The relationship is deemed a moderate quadratic
relationship.
Respiratory Phase:
Respiratory Phase Patterns for Healthy Participants for All Swallow Types
· The most common phase pattern was E-E at 72%. The next most common was
I-E at 14%, meaning that, 86% of all swallows were followed by an exhalation.
Distribution of Respiratory Phase Patterns
Respiratory Phase:
Respiratory Phase Patterns for Healthy Participants for All Swallow Types
· The most common phase pattern was E-E at 72%. The next most common was
I-E at 14%, meaning that, 86% of all swallows were followed by an exhalation.
Distribution of Respiratory Phase Patterns
• The most common respiratory phase pattern across
all ages was E-E at 72%. The next most common
was I-E at 14%, meaning that, 86% of all swallows
were followed by an exhalation.
• Five of the thirteen participants exhibited the E-E
pattern 100% of the time.
• Three participants exhibited three respiratory patterns,
while only one exhibited the I-I pattern.
References
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McFarland, D. H., Michel, Y., Orr, S. B., & Martin-Harris, B. (2011). Significance of nonrespiratory airflow during swallowing . Dysphagia, 27, 178-184. 3. Brodsky, M. B., McFarland, D. H., Dozier, T. S., Blair, J., Ayers, C.,
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Butler, S. G., Stuart, A., Pressman, H., Poage, G., & Roche, W. J. (2007). Preliminary investigation of swallowing apnea duration and swallow/respiratory phase relationships in individuals with cerebral vascular accident.
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7.Gewolb, I.H. & Vice, F.L. (2006). Abnormalities in the coordination of respiration and swallow in preterm infants with bronchopulmonary dysplasia. Developmental Medicine and Child Neurology, 48(7), 595-599. 8.
Gross, R. D., Atwood Jr, C. W., Ross, S. B., Olszewski, J. W., & Eichhorn, K. A. (2009). The coordination of breathing and swallowing in chronic obstructive pulmonary disease. American journal of respiratory and critical
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G., Strauss, M., Treole, K., Stuart, A., & Boutilier, S. (2003). Swallowing apnea as a function of airway closure. Dysphagia, 18(4), 293-300. 11. Kelly, B.N., Huckabee, M., Jones, R.D., Frampton, C.M.A. (2007). The early
impact of feeding on infant breathing-swallowing coordination. Respiratory Physiology and Neurobiology 156, 147-153. 12. Lefton-Greif, M.A. & McGrath-Morrow, S.A. (2007). Deglutition and respiration: Development,
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Limitations & Future Research
• One limitation of this study was the small population
size. Researchers chose two participants from each decade
surveyed, when possible. Findings may be more valid if
more participants were included for each decade
group. Furthermore, the population was drawn from one
geographic area, and no variables beyond age and gender
were accounted for. Future research may aim to include a
higher number of diverse participants in each decade group.
• Future research should focus on including child participants
younger than 4 and adults in the 80’s and 90’s decades. This
information could provide further insight to these researcher’s
speculations regarding the age effect on DAP of younger
children who are still maturing and older adults who are
facing even further physiological change with aging.
Conclusions
The DAP in healthy adults is longer in dry swallows versus
puree consistency, which may be a result of a swallow that is
volitional versus one that is not. Furthermore, there is more
stability in DAP in participants ages 20-50. More variability
exists in both younger and older populations. Lastly, RP in all
participants is followed by expiration a majority of the time.
Further research is needed to further investigate the cause of
the variability in ages 4-10 and 50-70. Additionally, expanding
the population to include data 0-4 and 70+ years of age is
needed to further capture how DAP and RP change across the
lifespan.
Instrumentation and Waveforms
Instrumentation:
• A KayPENTAX Digital Swallow Workstation (PENTAX
Medical, KayPENTAX Model 7120B, Montvale, NJ) and
nasal airflow recording device was used for digital
storage and retrieval of respiratory related airflow and
swallowing data.
• Nasal respiratory flow was captured through use of a
nasal cannula.
• A laryngeal microphone placed on the lateral aspect of
the thyroid cartilage was used to record swallow sounds.
Variables and Data Waveforms:
• Figure 1 illustrates nasal expiratory flow was shown on the
display as a positive-going trace, while inspiratory flow
was shown as a negative-going trace.
• Swallow sounds were displayed alongside nasal
respiratory flow to further distinguish swallowing events.
• Apneic pause appears as a flat line in between the two
phases that correspond with feedback from the laryngeal
microphone, indicative of a swallow.
Acknowledgments
The researchers of this study would like to acknowledge the
University of Cincinnati Research Council for providing funding
towards research with some of the enrolled participants.
Figure 2 A quadratic regression model with Age and DAP
(DAP’ = 2.12789 – 0.1141*Age + 0.00189 *Age2)
Figure 1: Waveform marked with events described: ss = swallow sounds, sa =
swallow apnea, EXP= expiration, INS= inspiration.9