Sympathetic and sensory nerve activation during negative pressure therapy of sternotomy wounds☆
Christian Torbrand
0
3
Angelica Wackenfors
0
3
Sandra Lindstedt
0
2
Rolf Ekman
0
1
Richard Ingemansson
0
2
Malin Malmsjo
0
3
0
This study was supported by the Anders Otto Sward FoundationyUlrika Eklund Foundation, Anna Lisa and Sven Eric Lundgren's Foundation for Medical Research, the Ake Wiberg Foundation, the M. Bergvall Foundation, the Swedish Medical Association, the Royal Physiographic Society in Lund, the Swedish Medical Research Council, the Crafoord Foundation, the Swedish Heart-Lung Foundation, the Swedish Government Grant for Clinical Research and the Swedish Hypertension Society
1
Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, The Sahlgrenska Academy at University of Gothenburg
, Molndal,
Sweden
2
Department of Cardiothoracic Surgery, Lund University Hospital
,
Lund, Sweden
3
Department of Medicine, Lund University Hospital
,
Lund, Sweden
Negative pressure wound therapy (NPWT) has been adopted as the first-line treatment for poststernotomy mediastinitis as a result of the excellent clinical outcome. The knowledge concerning the effects of NPWT on the cardiovascular system and homeostasis is still limited. The aim of the present study was to investigate whether the plasma levels of neurohormones change during NPWT. Six pigs underwent median sternotomy followed by NPWT at -125 mmHg. The plasma levels of noradrenaline, adrenaline, neuropeptide Y, substance P, vasoactive intestinal peptide (VIP), and calcitonin gene-related peptide (CGRP) were determined before (0 min) and 5, 20, 60 and 180 min after the application of NPWT. The results show a transient increase in the plasma levels of noradrenaline and adrenaline when NPWT was applied. The plasma level of the adrenergic co-transmitter neuropeptide Y was higher in NPWT - than in sham-treated pigs, after 180 min of negative pressure. After 180 min of NPWT there was an increase in the plasma levels of the sensory nerve transmitter substance P, while no such effect was observed for CGRP or VIP. In conclusion, the results suggest sympathetic nerve activation during NPWT. This may be the result of an increase in workload on the heart during the initial phase of NPWT. 2008 Published by European Association for Cardio-Thoracic Surgery. All rights reserved.
1. Introduction
Negative pressure wound therapy (NPWT) has remarkable
effects on the healing of chronic and difficult wounds and
has drastically reduced the mortality in poststernotomy
mediastinitis following cardiac surgery. The technique
entails application of negative pressure to a sealed, airtight
wound. The suction force created by the subatmospheric
pressure enables the drainage of excessive fluid and debris,
which leads to the removal of wound edema, reduction in
bacterial count and enhanced granulation tissue formation
w1, 2x. Knowledge of the effects of NPWT in a sternotomy
wound is limited w1x. The organs in the mediastinum are
hemodynamically crucial and both vulnerable bypass grafts
and reduced cardiac function should be taken into
consideration during NPWT of sternotomy wounds.
Recent publications have reported right ventricular
rupture during NPWT in cardiac surgery w3x. Also, reduced
cardiac output during NPWT has been reported w4x. No
study has yet been performed to examine the effect of
NPWT on neurohormones, many of which are considered to
be released upon increased cardiac load. In the present
study, we analyzed the plasma levels of noradrenaline,
adrenaline, neuropeptide Y, substance P, vasoactive
intestinal peptide (VIP), and calcitonin gene-related peptide
(CGRP).
Noradrenaline is a transmitter that is released by the
sympathetic nerve terminals. The sympathetic nervous
system also acts on the adrenal medulla to release
catecholamines including adrenaline and, to a lesser extent,
noradrenaline. Neuropeptide Y is co-localized with
norepinephrine in sympathetic nerve terminals and is released
when the rate of nerve firing is high w5x. Neuropeptide Y
enhances the effects of noradrenaline and accounts for the
long-lasting effects of sympathetic nerve transmission w5x.
Sympathetic nerve activation results in increased cardiac
pumping, sodium retention via the kidneys and constriction
and hypertrophic effects on the peripheral vasculature.
VIP is a co-transmitter in parasympathetic nerves w6x. It
is involved in the autonomic regulation of the
cardiovascular system, where it exerts positive inotropic and
chronotropic effects, and causes coronary vasodilatation.
Substance P and CGRP are released from primary afferent
neurons and act in the periphery to stimulate vasodilatation
and promote inflammation w7x. This mechanism, known as
neurogenic inflammation, amplifies and sustains an
inflammatory reaction.
In the present study, the effects of NPWT on the plasma
levels of neurohormones were examined in a pig sternotomy
wound model. Noradrenaline, adrenaline, neuropeptide Y,
VIP, substance P and CGRP were analysed before (0 min)
and after 5, 20, 60 a (...truncated)