Chronic widespread pain (CWP) is a complex condition characterized by central hyperexcitability and altered descending control of nociception. However, nociceptive input from deep tissues is suggested to be an important drive. N-Acylethanolamines (NAEs) are endogenous lipid mediators involved in regulation of inflammation and pain. ⋯ This is the first study demonstrating that CNSP and CWP differ in levels of NAEs in response to a low-force exercise which induces pain. Increases in pain intensity as a consequence of low-force exercise were associated with low levels of PEA and SEA in CNSP and CWP. These results indicate that PEA and SEA have antinociceptive roles in humans.
This study investigated whether one becomes more quickly aware of innocuous somatosensory signals at locations of the body where pain is anticipated. Undergraduate students (N=20) indicated which of 2 stimuli that were administered to each hand using a range of stimulus onset asynchronies (SOAs), was presented first. Participants were instructed that the color of a cue (1 of 2 colors) signaled the possible occurrence of pain on 1 hand (threat trials). ⋯ Results showed that during threat trials tactile stimuli on the hand where pain was expected, were perceived earlier in time than stimuli on the "neutral" hand. These findings demonstrate that the anticipation of pain at a particular location of the body resulted in the prioritization in time of somatosensory sensations at that location, indicating biased attention towards the threatened body part. The value of this study for investigating hypervigilance for somatosensory signals in clinical populations such as patients with chronic lower back pain is discussed.
Few studies have examined abuse of prescription opioids among individuals with chronic pain under buprenorphine/naloxone (Bup/Nx) maintenance. The current 7-week inpatient study assessed oral oxycodone self-administration by patients with chronic pain who had a history of opioid abuse. Participants (n=25) were transitioned from their preadmission prescribed opioid to Bup/Nx. ⋯ However, factors associated with oxycodone preference were lower Bup/Nx maintenance dose, more withdrawal symptoms and more pain. These data suggest that Bup/Nx was effective in reducing pain and supplemental oxycodone use. Importantly, adequate management of pain and withdrawal symptoms by Bup/Nx may reduce oxycodone preference in this population.
This massively-multicenter (235 hospitals, 24 countries; mainly Europe & N. America) cohort study investigated post-operative morbidity and mortality in those with confirmed SARS-CoV-2 infection.
Why is this significant?
Early data suggested that COVID-19 patients who underwent even minor elective surgery suffered worse post-operative outcomes, particularly higher mortality.
This large cohort study confirms these concerns and will assist decision making around the timing of surgery for COVID-19 patients and the process for re-commencing elective surgery in communities hardest hit by the pandemic.
What did they do?
Over a 3 month period in early 2020 the researchers analysed 1,128 patients who underwent emergency (74%) or elective (25%) surgery across 24 countries. Patients diagnosed with COVID seven days pre-op or 30 days post-op were included, although the majority of patients (74%) had SARS-CoV-2 infection diagnosed post-operatively.
And they found?
30-day mortality was extremely high (24%).
Pulmonary complications (pneumonia, ARDS or unexpected post-op ventilation) were very common (51%) and were associated with an even higher mortality (38%; and 83% of all deaths).
Mortality was unsurprisingly associated with older age ≥ 70 years, male sex, ASA ≥ 3, emergency surgery, major surgery, and malignancy.
Other interesting observations...
- Nonetheless 'lower-risk' groups still suffered significant 30-day mortality rates, eg. 30-49 year olds (6%), women (18%), ASA 1-2 (12%), no-comorbidities (7%).
- Being asymptomatic at admission did not have a significant protective effect (22% vs 27% mortality).
- Dyspnoea and/or sputum on admission were the only symptoms associated with worse outcomes.
- 20% of patients suffered ARDS, with a 63% mortality rate.
- Although emergency surgery was higher risk, elective surgery still carried a 19% mortality rate. Even minor surgery resulted in a 16% mortality rate!
- Even obstetrics (2% mortality) and gynaecology (5%) demonstrated orders of magnitude-higher mortality than expected.
- There was no statistically significant difference between local, regional or general anaesthesia.
- Pulmonary embolus was only seen in 2% at 30 days and when present did not appear to impact mortality.
Why such high post-operative COVID mortality?
The authors suggest this could be due to the combination of pro-inflammatory cytokine and immunosuppressive responses to surgery, and/or mechanical ventilation associated with general anaesthesia (although the later was not significantly associated with higher mortality).
Surgery for those with known or suspected COVID-19 should be avoided or delayed until after recovery from infection, as allowed by the underlying surgical pathology. When surgery cannot be delayed less-invasive surgery is preferable, and post-operative recovery should be closely monitored.
Keep in mind
Although RT-PCR testing was the main diagnostic test, in some settings clinical criteria (6%) and/or chest CT (7%) were instead used for diagnosis. Additionally, hospital data collection during a pandemic emergency carries higher risk of error, although this should not effect the broad validity of the research conclusions.summary
Pontospinal noradrenergic neurons form part of an endogenous analgesic system that suppresses acute pain, but there is conflicting evidence about its role in neuropathic pain. We investigated the chronology of descending noradrenergic control during the development of a neuropathic pain phenotype in rats following tibial nerve transection (TNT). A lumbar intrathecal cannula was implanted at the time of nerve injury allowing administration of selective α-adrenoceptor (α-AR) antagonists to sequentially assay their effects upon the expression of allodynia and hyperalgesia. ⋯ Contralateral thermal hyperalgesia was also reversibly uncovered by yohimbine administration in a contact heat ramp paradigm in anaesthetised TNT rats. Following TNT there is an engagement of inhibitory α2-AR-mediated noradrenergic tone which completely masks contralateral and transiently suppresses the development of ipsilateral sensitization. This endogenous analgesic system plays a key role in shaping the spatial and temporal expression of the neuropathic pain phenotype after nerve injury.