Background & Aims
Background
There is a bidirectional relationship between pain and respiration [1]. Other factors such as biomechanics of thorax may also influence respiratory function [2]. Changes in carbon dioxide (CO2) has been seen in local pain conditions such as cervical or lumbal pain. Such relationship has not been confirmed in people with FM. Other disturbance of respiratory function has been observed in FM but the evidence is scarce so far.
Aim
The purpose of this study was to investigate whether people with fibromyalgia (FM) have changes in arterial blood gas pressure indicating dysfunctional breathing and compare with healthy controls. A secondary aim was to investigate the influence of pain intensity and thoracic mobility on these blood gases.
Methods
Thirty-six women diagnosed with FM and 36 healthy controls matched for age and gender participated in this cross-sectional study. Arterial blood gas pressure was obtained from the radial artery and analysed for paCO2, paO2, bicarbonate, base excess, pH and lactate. A stepwise approach of blood gas analyses was employed to determine respiratory chronicity.
Pressure pain threshold (PPT) was assessed over paraspinal muscles between C7-T7 and thoracic mobility i.e. the expansion of the chestwall was examined in the level of proc xiphoideus.
Results
Women with FM had significantly lower paCO2 (p=0.013) compared to healthy controls. For a subgroup of women with FM, the lower paCO2 was categorized as a chronic respiratory disturbance which differed from controls (p=0.042). Decreased thoracic mobility correlated with decreased paCO2 and base excess among women with FM. There was no correlations with pain sensitivity.
Conclusions
In this study, women with FM had significantly lower arterial carbon dioxide pressure compared to healthy controls, of which a subgroup demonstrated chronic changes. Thoracic mobility may be a contributing factor to dysfunctional breathing in this patient group.
References
1. Jafari H, Courtois I, Van den Bergh O, Vlaeyen JWS, Van Diest I. Pain and respiration: a systematic review. Pain 2017 Jun;158(6):995-1
2. Forti M, Zamuner AR, Andrade CP , Silva E. Lung function, respiratory muscle strength, and thoracoabdominal mobility in women with fibromyalgia syndrome. Respir Care 2016 Oct;61(10):1384-90.