Wavelet analysis of electrical activity from respiratory muscles during coughing and sneezing in anesthetized rabbits, in 84th PHYSIOLOGICAL DAYS, Slovakia, 2008

1. WAVELET ANALYSIS OF ELECTRICAL ACTIVITY FROM RESPIRATORY MUSCLES
DURING COUGHING AND SNEEZING IN ANESTHETIZED RABBITS
Juliana Knocikova, Ivan Poliacek, Jan Jakus, Helena Barani
Department of Medical Biophysics, Jessenius Faculty of Medicine, Comenius University, Martin, Slovakia
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84th PHYSIOLOGICAL DAYS, MARTIN, 6th - 8th february 2008
Results
Abstract
Cough and sneeze are important defensive reflexes of the airways. Despite a very high
similarity, some differences in generation of the patterns of these two behaviors were
suggested. The main aim of our study was to analyze and compare a frequency
composition of electrical activity in the respiratory muscles in coughing and sneezing.
Data were taken from eight adult rabbits under pentobarbital anesthesia. During
inspiratory period, we compared electrical activity of diaphragm in the tracheobronchial
cough, sneeze, and quiet breathing. During expiratory period of coughing and sneezing,
electromyograms (EMG) were used from the abdominal muscles. We applied the wavelet
analysis to determine a time-frequency distribution of energy during mentioned behaviors
due to non-stationary character of EMG signals.
Inspiratory durations of cough, sneeze and quiet inspiration were similar. The maximum
of inspiratory power has occured later in sneeze than during quiet inspiration (p < 0.05).
The total inspiratory power during sneeze was higher compared to those found in the
cough (p < 0.05) and quiet inspiration (p < 0.01). Lower frequencies contributed to an
increase of the power even significantly more than in the cough (287.5 Hz up to 575 Hz,
p < 0.01; under 287.5 Hz, p < 0.05). We found similar distribution of energy in the cough
and quiet inspiration. In quiet inspiration the maximum of energy occured at lower
frequencies comparing to the sneeze (p < 0.01). There was similar rate of contribution to
the total power (ratio of the power in the frequency band to the total power) for the
sneeze and cough, the differences were only found in comparison with quiet inspiration.
The expiratory period of coughing was longer compared to that in sneeze (p = 0.0006).
No significant differences were found in the time – frequency energy distributions.
Our results indicate the possibility that there may exist significant differences in
mechanism of generation of the cough, sneeze and quiet breathing.
REFERENCES
BARÁNI H, JAVORKA M, JAKUŠ J, POLIAČEK I, STRÁNSKY A 2005: Spectral
analysis of respiratory responses to tracheobronchial and laryngeal stimulation in
cats. Acta Vet Brno 74: 191-198
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
JAKUŠ J, TOMORI Z, STRÁNSKY A 2004: Neuronal determinants of of breathing,
coughing and related motor behaviors. Wist, Martin, 335 p.
KORPÁŠ J, TOMORI Z : Cough and other respiratory reflexes. Progress in
Respiration Research, vol. 12 Basel: S. Karger 1979, 356 p.
SHANNON R, BAEKEY DM, MORRIS KF, LINDSEY BG 1996: Brainstem respiratory
networks and cough. Pulm Phamacol 9: 343/347
Supported by Vega 1/2274/05
Conclusions
Time - frequency energy distribution of inspiratory DIA
activity exposed similarities between cough and eupnea
supporting the concept of common respiratory / cough central
pattern generator.
Inspiration in sneeze showed increased activity in lower
frequencies comparing with the cough inspiration.
Numerous serious differences between sneeze and quiet
inspirations indicate the involvement of specific neuronal
structures in generation of sneeze.
No significant difference in time – frequency energy
distribution of expiratory ABD activity in coughing and sneezing
suggests an existance of non – specific mechanism producing
expiratory activity during different defensive airway reflexes.
Fig. 2. 3-D wavelet scalogram of the inspiratory activity during tracheobronchial (TB)
cough (A), sneeze (B) and breathing (C). TB cough and quiet breathing showed similar
time – frequency energy distribution. Shift of the energy to the lower frequency bands is
typical for sneezing compared to the TB cough.
Introduction
Background
Despite similarities between cough and sneezing, there are differences
in their motor patterns. Multiresolution analysis of respiratory muscles
activity might expose significant differences in their frequency
characteristics suggesting specific neuronal components important for
generation of these behaviors.
Objective
The main objective of the study was to analyse and compare time-
frequency energy distribution resulting from inspiratory and expiratory
activity of respiratory muscles during eupnoe, tracheobronchial (TB)
cough and sneeze.
Methods
Experimental animals
Experiments were performed on 8 adult rabbits (chinchilla) of both
sexes (3.83  0.52kg).
Anesthesia
Anesthesia was induced by a mixture of ketamine (Narkamon, Spofa; 25
mg/kg) and xylazine (rometar, Spofa; 5 mg/kg) i.m., then pentobarbital
(Vetbutal, Polfa, full dose of 30-40 mg / kg) i.v. was used to replace the
original anesthesia.
Stimulation
TB cough was induced from the tracheal-bronchial region of the
airways, sneeze from the nasal mucosa. Mucosae were stimulated
mechanically by a soft plastic catheter.
Recording
The electrical inspiratory discharges of the diaphragm (DIA) and
expiratory activity of abdominal muscles (ABD) were recorded during
55 TB coughs, 48 sneezes, and the DIA activity also during 45 quiet
inspirations. We used bipolar fine wire teflon coated stainless steel
hook electrodes.
Data analysis
We analyzed frequency range (100 Hz – 3000 Hz).
Analysis was performed with self-developed computer program using
MATLAB programming enviroment (HUMUSOFT, v.7.3.0.267).
Fig. 3. Frequency
composition (see
Table 1.) of the
diaphragm activity
during inspiration in
tracheobronchial
(TB) cough and
sneeze. Inspiratory
power of TB cough
and sneeze is
normalized to the
avegaged power of
quiet inspiration
(100%). * p < 0.05,
** p < 0.01
Statistics
Repeated measures analysis of variance, paired t-test, Wilcoxon matched-
pairs signed-ranks test and Chi-squared test for Independence were used
for statistical processing of the data. Differences were considered
significant for p < 0.05. Statictical calculations were performed by
GraphPad InStat (v. 3.06) software.
Fig.1. Electrical activity in the diaphragm during the preparatory inspiration of the
tracheobronchial cough (A) and several consecutive sneeze reflexes (B) on the left
hand side. On the right hand side, morlet mother wavelet in its basic position (red)
and modificated by scaling (blue) and translation (green). Mother wavelet modification
results in its adaptation to the signal properties and consequently better sensitivity.
Wavelet transformation
Table 1. Statistical comparison of parameters related to the time – frequency energy
distribution.
DIA - diaphragm, ABD - abdominal muscles;
P
TOT
- total power of individual bursts in the scale domain,
P
M
- the magnitude of its maximum, P
S
- wavelet scale at which it occured, P
T
–
time at which maximal power occured, P
1
– P
6
- frequency bands (P
1
–
frequencies above 958 Hz, P
2
- (575 – 958) Hz, P
3
- (287 – 575) Hz, P
4
- (192 –
287) Hz, P
5
- (144 – 192) Hz, P
6
- frequencies below 144 Hz), PP
1
– PP
6
- rate of
contribution of the power in the frequency band to the total power, P
MAX
- the
frequency band that contributes to the total power at highest rate;
-, non-significant; * p < 0.05, ** p < 0.01, *** p < 0.001, **** p < 0.0001