Multiresolution analysis based investigation of the defensive airway reflexes in MEDICAL PHYSICS AND BIOMEDICAL ENGINEERING WORLD CONGRESS, Munich, Germany, 2009

1. Multiresolution analysis based investigation of the defensive airway
reflexes
Juliana Knocikova
Department of Physics, Faculty of electrical engineering, University of Žilina,
Slovakia
MEDICAL PHYSICS AND BIOMEDICAL ENGINEERING WORLD CONGRESS, 7th - 12th september 2009, MUNICH
Abstract
Aim. Aspiration reflex (AspR) known as a short – lasting but very
intense inspiratory motor activity without subsequent active
expiration is resulting in a kind of a spasmodic inspiration
accompanied by many respiratory, cardiovascular and
neurophysiological changes. The main goal of this study was to
analyze the phrenic nerve electrical activity during AspR and
compare features of this response with inspiratory activity during
tracheobronchial (TB) cough and eupnoea.
Methods. Reflexes were eliticed mechanically in eight adult
anaesthetized cats. Moreover, results were compared during
chloralose and pentobarbital anaesthesia. Time – frequency
energy distribution of the phrenic nerve recordings enabled a
multiresolution analysis of non – stationary activities. Based on
continuous wavelet transform algorithm, an optimal time –
frequency resolution was reached.
Results. The phrenic nerve activity shows a specific time –
frequency energy distribution during AspR, comparing to both the
cough and eupnoeic patterns of inspiration. The extremely high
power of phrenic nerve bursts in AspR (p < 0.0001) was
cumulated within lower frequency bands (p < 0.05). Moreover,
the energy distribution in AspR remained stabile, irrespective of
two anaesthetics being used in cats contrary to the other
examined behaviours. Chloralose anaesthesia resulted in a
significant decrease of parameters related to the quantity of
energy in a cough (p < 0.02) and quiet inspiration (p < 0.02).
Conclusion. These results support an idea of specific
information processing at a stage of central neural integration of
AspR underlying its powerful ability to influence various severe
functional disorders with potential implications for model
experiments and clinical practice.
REFERENCES
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phase of the phrenic neurogram of eupnoea in the
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COHEN MI, SEE WR, CHRISTAKOS CN, SICA AL 1987:
High – frequency and medium - frequency components
of different inspiratory nerves discharges and their
modification by various inputs. Brain Res 417: 148 – 152
KNOCIKOVA J., JAKUS J., POLIACEK I., TOMORI Z.:
Frequency analysis of the phrenic nerve activity during
aspiration reflex and inspiratory phase of
tracheobronchial cough in anaesthetized cats [abstract].
Book of abstracts. Congress on Sleep Medicine,
Slovakia, 2007
KORPAS J, TOMORI Z : Cough and other respiratory
reflexes. Progress in Respiration Research, vol. 12
Basel: S. Karger 1979, 356 p.
Background
Statistics
Unpaired t- test, unpaired t- test with Welch correction,
Mann-Whitney test, one-way ANOVA and Kruskal-Wallis
tests were used for the statistical data evaluation.
Differences were considered significant for p < 0.05.
knocikova@fel.uniza.sk
Fig. 1. Different expressions of the respiratory output activity. Part A illustrates
an airflow record of the aspiration reflex preceded and followed by a quiet
breath. The corresponding phrenic nerve activity is indicated in part B, below
on the left side. Wavelet scalogram of the phrenic nerve activity during AspR is
drawn on the right side (part C). The energy of the phrenic nerve burst is
expressed as a function of time and the wavelet scale (related to the
frequency). Part D illustrates basic relationships between different inspiratory
patterns in PTBT anaesthesia. Strong time - domain energy is a typical feature
of AspR through relatively short duration. Duration and parameter MAX
T
are
standardized to quiet inspiration representing fundamental values. MAX
T
–
maximum of time – domain power (result of vertical scalogram integration), a.u.
– arbitrary units. Wavelet scale and wavelet coefficients are dimensionless
values. ** p  0.001, * p  0.05.
Methods
Experiments were elicited on 8 adult cats of both sexes under chloralose and
pentobarbotal anaesthesia. Phrenic nerve activity was investigated within interval
(30 - 1000) Hz.
Wavelet transformation
where  is the transforming function called the mother wavelet,
 is the wavelet translation,
s is the wavelet scale
Fig. 2. Phrenic nerve activity. The neurogram is expressed as time –
expanded wave form, wavelet scalogram and horizontal and vertical
scalogram integration (from top to bottom) in aspiration reflex (A),
inspiratory phase of tracheobronchial cough (B) and quiet inspiration (C)
in cats in PTBT anaesthesia. The most pronounced cumulation of the
energy within lower frequency bands (higher scales) is a typical for
AspR. The TB cough indicates higher relative power in the higher
frequency bands, compared to AspR. a.u. – arbitrary units.
Fig. 3. Wavelet scalograms of the phrenic nerve electrical activity in
aspiration reflex (A), the inspiratory phase of TB cough (B) and quiet
inspiration (C) in cats under chloralose anaesthesia. During AspR, the
energy is cumulated within lower frequency bands (higher wavelet
scales) of the phrenic nerve activity, compared to the inspiratory phase
of coughing and eupnoea. TB cough is characterised by long and more
pronounced ”ramp-like“ preparatory inspiration, the maximum of power
was found at the end of the phrenic nerve activity.
Results
dt
s
t
tx
s
dtttxsW s )()(
1
)()(),( *
,

 

 




Conclusions
The electrical activity of the phrenic
nerve in AspR showed an extremely
high maximal power, cumulated in the
lower frequency bands
Damping of the high frequency
bands contribution to the total energy is
a typical feature for the inspiratory
phase of the cough under comparison
with quiet inspiration
Parameters of the AspR activity are
not significantly influenced by
anaesthesia in a contrast to inspiratory
phase of breathing and coughing
Chloralose anaesthesia caused
a decrease of parameters related to the
quantity of energy in cough and quiet
inspirstion
Fig. 4. Effect of
anaesthesia. Changes
in the frequency rates
(power rate of the
pertinent frequency
band to the total power
of the burst expressed
as percentage) are
described as a result of
anaesthetics on the
aspiration reflex (A),
inspiratory phase of TB
cough (B) and quiet
inspiration (C) in cats.
Red line: CH
anaesthesia, blue line:
PTBT anaesthesia. CH
anaesthesia resulted in
a decrease of the total
power, most visible in
lower frequency bands
(higher scales – values
on the x-axis), but not in
higher frequency bands.
The AspR represented
the most stable model
of the neural inspiratory
activity. The obvious
differences in the
energy distribution
caused by anaesthesia
were found at the
inspiratory phase of
coughing.