Slow breathing reduces sympathoexcitation in
chronic obstructive pulmonary disease
Tobias Raupach, MD
Florian Bahr
Peter Herrmann, PhD
Lars Lüthje, MD
Karsten Heusser, PhD
Gerd Hasenfuß, MD
Luciano Bernardi, MD
Stefan Andreas, MD
Online data supplement
Raupach et al.: Slow breathing in COPD
First Revision – Manuscript number ERJ-01096-2007
Methods
Microneurography
Sympathetic nerve activity was measured using microneurographic recordings of
efferent muscle sympathetic nerve activity (MSNA) in the peroneal nerve of the right
leg. After mapping the course of the peroneal nerve around the head of the fibula by
transcutaneous electrical stimulation (Stimuplex HNS 11, B Braun, Melsungen,
Germany), a tungsten microelectrode (shaft diameter 200 µm, tip of 1–5 µm) was
inserted into the nerve. A reference electrode was inserted subcutaneously 3 cm
away. The nerve signals underwent amplification (by 50,000), bandpass filtering
(band width 700–2,000 Hz), and passage through a resistance-capacitance
integrating network with a time constant of 0.1 second, providing a mean voltage
display of sympathetic nerve activity (Nerve Traffic Analysis System, model 662C-3,
University of Iowa, Iowa City, USA). The procedure and the criteria for a satisfactory
recording of muscle sympathetic nerve activity have been described previously [1, 2].
Sympathetic bursts were identified by inspection of the mean voltage neurogram and
quantified as bursts/minute and bursts/100 heartbeats in order to correct for
differences in heart rate.
Baroreflex sensitivity
Baroreflex sensitivity was measured by spectral analysis using the "alpha-angle"
method, as previously described [3]. Simultaneous continuous recordings of ECG
and blood pressure were sampled at a rate of 256 Hz. Spectral analysis of R-R
interval and systolic and diastolic blood pressure was performed after linear
detrending by an autoregressive algorithm. Spectral power was calculated as
absolute power (variance of the time series), low-frequency (LF) power (0.03-0.15
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Raupach et al.: Slow breathing in COPD
First Revision – Manuscript number ERJ-01096-2007
Hz), and high-frequency (HF) power (0.15-0.4 Hz) [4]. Spontaneous baroreflex
sensitivity was estimated as the square root of the relation between LF power of the
R-R interval and systolic blood pressure. A mathematical function (squared
coherence) was used to prove that fluctuations in the RR interval are in fact related to
similar fluctuations in blood pressure [5].
Blood samples
A small intravenous catheter was inserted into an antecubital vein before starting the
protocol. After a rest of 20 minutes, venous blood samples for catecholamine
determinations were drawn into heparinized tubes without applying a tourniquet. The
samples were centrifuged immediately and aliquots were stored in screw-top cups at
-80° C before carrying out laboratory analyses. Arterial blood gases were measured
in an arterial blood sample taken from the radial artery before starting the protocol.
Data acquisition and analysis
The Modular Intensive Care Data Acquisition System (MIDAS) hardware contains a
full programmable 16 channel amplifier and an analog digital converter (ADC)
facilitating filtering, amplification and digitalization of biological signals. The ADC
delivers full 12-bit accuracy when sampling multiple channels at high gains and fast
rates. Several parameters (e.g. gain, sampling rate, and signal range) can be set
individually for each channel. The digital signals are first stored in a FIFO (first-infirst-out) buffer and then transferred via USB for further processing.
The software for low-level communication between the measuring hardware and the
PC was developed with MS Visual C++. The user interface and complete MIDAS
software were developed with the graphical programming language G (LabVIEW 6.1,
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Raupach et al.: Slow breathing in COPD
First Revision – Manuscript number ERJ-01096-2007
National Instruments, Austin TX, USA). Communication between this software and
MIDAS hardware components is based on a DLL file. The user can select different
gains (0.1- to 1000-fold), and sample rates (16 Hz to 8 kHz) for each channel. It is
possible to perform a 0-point and 2-point calibration for each signal. The waveform
data are stored in a special binary file format. Parts of the raw binary signal can be
exported to an ASCII - spreadsheet which can be re-imported to statistics software.
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Raupach et al.: Slow breathing in COPD
First Revision – Manuscript number ERJ-01096-2007
References
1.
Delius W, Hagbarth KE, Hongell A, Wallin BG. General characteristics of
sympathetic activity in human muscle nerves. Acta Physiol Scand 1972;84:6581.
2.
Vallbo AB, Hagbarth KE, Torebjork HE, Wallin BG. Somatosensory,
proprioceptive and sympathetic activity in human peripheral nerves. Physiol
Rev 1979;59:919-957.
3.
Malliani A, Pagani M, Lombardi F, Cerutti S. Cardiovascular neural regulation
explored in the frequency domain. Circulation 1991;84:482-92.
4.
Keyl C, Schneider A, Gamboa A, Spicuzza L, Casiraghi N, Mori A, Ramirez
RT, Leon-Velarde F, Bernardi L. Autonomic cardiovascular function in highaltitude Andean natives with chronic mountain sickness. J Appl Physiol
2003;94:213-9.
5.
Bernardi L, Porta C, Spicuzza L, Bellwon J, Spadacini G, Frey AW, Yeung LY,
Sanderson JE, Pedretti R, Tramarin R: Slow breathing increases arterial
baroreflex sensitivity in patients with chronic heart failure. Circulation
2002;105:143-5
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Raupach et al.: Slow breathing in COPD
First Revision – Manuscript number ERJ-01096-2007
Figure legends
Figure S1: Display of continuous tracings of muscle sympathetic nerve activity
(MSNA, unprocessed and integrated data), blood pressure and electrocardiogram
(ECG) in a healthy control subject.
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Raupach et al.: Slow breathing in COPD
First Revision – Manuscript number ERJ-01096-2007
Tables
Table S1. Heart rate during spontaneous, regularized and slow breathing.
Heart rate
presp
pinter
79.0  3.2
COPD
Baseline
0.976
patients
79.0  3.1
Respiratory rate 6/min
0.688
69.7  1.7
Healthy
Baseline
0.507
controls
70.3  1.9
Respiratory rate 6/min
79.8  3.1
Respiratory rate 15/min
COPD
0.193
patients
79.1  3.1
Respiratory rate 6/min
0.629
71.5  1.7
Respiratory rate 15/min
Healthy
0.179
controls
70.3  1.9
Respiratory rate 6/min
presp, p value for effect of reducing respiratory rate; pinter, p value for effect of interaction between
subject group and intervention.
Table S2. Systolic and diastolic blood pressure during spontaneous, regularized and
slow breathing.
Systolic blood pressure
presp
pinter
127.5  8.2
COPD
Baseline
0,219
patients
122.4  6.8
Respiratory rate 6/min
0,388
135.6  7.6
Healthy
Baseline
0,698
controls
134.6  7.5
Respiratory rate 6/min
123.7  6.8
COPD
Respiratory rate 15/min
0,314
patients
122.4  6.8
Respiratory rate 6/min
0,102
130.7  5.9
Respiratory rate 15/min
Healthy
0,163
controls
134.6  7.5
Respiratory rate 6/min
Diastolic blood pressure
presp
pinter
62.8  3.5
COPD
Baseline
0,173
patients
64.7  4.0
Respiratory rate 6/min
0,259
68.7  3.4
Healthy
Baseline
0,684
controls
68.0  2.7
Respiratory rate 6/min
61.2  3.5
Respiratory rate 15/min
COPD
0,053
patients
64.7  4.0
Respiratory rate 6/min
0,479
66.0  2.4
Respiratory rate 15/min
Healthy
0,172
controls
68.0  2.7
Respiratory rate 6/min
presp, p value for effect of reducing respiratory rate; pinter, p value for effect of interaction between
subject group and intervention.
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