Pain
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Chronic pain after surgery is recognised as an important post-operative complication; recent studies have shown up to 30% of patients reporting persistent pain following mastectomy and inguinal hernia repair. No large-scale studies have investigated the epidemiology of chronic pain at two operative sites following coronary artery bypass grafting (CABG). This paper reports the follow-up of a cohort of 1348 patients who underwent cardiac surgery between 1996 and 2000 at one cardiothoracic unit in northeast Scotland. ⋯ Prevalence of chronic pain decreased with age, from 55% in those aged under 60 years to 34% in patients over 70 years. Patients with pre-operative angina and those who were overweight or obese (BMI>/=25) at the time of surgery were more likely to report chronic pain. Chronic pain following median sternotomy and saphenous vein harvesting is more common than hitherto reported and that patients undergoing CABG should be warned of this possibility.
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Comparative Study
Prolonged duration local anesthesia from tetrodotoxin-enhanced local anesthetic microspheres.
There is interest in developing prolonged duration local anesthesics. Here we examine whether tetrodotoxin (TTX) can be used to prolong the block from bupivacaine microspheres with and without dexamethasone. Rats received sciatic nerve blocks with 75 mg of microspheres containing 0.05% (w/w) TTX, 50% (w/w) bupivacaine and/or 0.05% (w/w) dexamethasone. 0.1% (w/w) TTX microspheres were also tested. ⋯ In summary, coencapsulation of TTX in controlled release devices containing bupivacaine and dexamethasone resulted in very prolonged nerve blocks. As formulated here, this preparation had a narrow margin of safety. While the myotoxicity appears consistent with the well-known reversible myotoxicity associated with local anesthetics, its long-term significance remains to be established.
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Comparative Study
DPDPE-UK14,304 synergy is retained in mu opioid receptor knockout mice.
When agonists to alpha(2)adrenergic receptor (AR) and delta opioid receptor (DOR) are co-administered, they act synergistically to inhibit nociceptive elicited behavior. Some previous studies of synergism have used the DOR-selective agonist [D-Pen(2),D-Pen(5)]-enkehphalin (DPDPE), however, DPDPE has been shown to be less potent in mu opioid receptor-knockout (MOR-KO) mice. It is possible, therefore, that MOR contributes to the synergism of DPDPE with the alpha(2)AR agonists. ⋯ Interestingly, isobolographic analysis showed that, despite substantial loss of DPDPE potency in MOR-KO, DPDPE-UK14,304 synergism is fully retained. Collectively, these experiments demonstrate that although MOR participates in DELT II- and DPDPE-mediated spinal antinociception, DOR independently participates in synergistic antinociception with alpha(2)AR. Resolution of the roles of the opioid receptor subtypes in opioid agonist-induced effects may require comparison of the effects of multiple selective agonists in knockout animals.
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Comparative Study
Selective attentional bias, conscious awareness and the fear of pain.
It has been suggested that healthy individuals with a high fear of pain possess a selective attentional bias in favour of pain-related material. However, evidence is limited since only a few studies have been conducted to date. In addition, these studies have not yet examined whether such attentional biases are relatively automatic, and so are outside conscious control. ⋯ Furthermore, we also found that when stimuli were masked, this bias was reversed. Neither effect was found amongst participants high in the fear of pain. Together, these findings suggest that the ability to orient away from pain-related stimuli may be under conscious control in low fearful people, whereas such a mechanism does not seem to exist in those high in the fear of pain.
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The Transtheoretical model of stages of behaviour change has stimulated research interest in relation to chronic pain, yet studies using the Pain Stages of Change Questionnaire (PSOCQ; Pain (72) 1997 227) have reported inconsistent findings and have generally utilized pain-clinic samples. The aims of the current study were to assess the general validity of the PSOCQ with a non-pain-clinic sample of patients with chronic pain, and to examine the utility of the stages of change model as applied to this population. ⋯ The findings demonstrated a number of limitations of the PSOCQ in terms of its ability to classify individuals into specific stages of change. The stages of change model requires adaptation in order to be useful for treatment planning in a non-pain-clinic sample of patients with chronic pain.