Dynamic cerebral autoregulation is preserved during orthostasis and intrathoracic pressure regulation in healthy subjects: A pilot study

Resistance breathing may restore cardiac output (CO) and cerebral blood flow (CBF) during hypovolemia. We assessed CBF and cerebral autoregulation (CA) during tilt, resistance breathing, and paced breathing in 10 healthy subjects. Blood velocities in the internal carotid artery (ICA), middle cerebral arteries (MCA, four subjects), and aorta were measured by Doppler ultrasound in 30° and 60° semi-recumbent positions. ICA blood flow and CO were calculated. Arterial blood pressure (ABP, Finometer), and end-tidal CO2 (ETCO2) were recorded. ICA blood flow response was assessed by mixed-models regression analysis. The synchronization index (SI) for the variable pairs ABP-ICA blood velocity, ABP-MCA velocities in 0.005-0.08 Hz frequency interval was calculated as a measure of CA. Passive tilting from 30° to 60° resulted in 12% decrease in CO (p = 0.001); ICA blood flow tended to fall (p = 0.04); Resistance breathing restored CO and ICA blood flow despite a 10% ETCO2 drop. ETCO2 and CO contributed to ICA blood flow variance (adjusted R2: 0.9, p < 0.0001). The median SI was low (<0.2) indicating intact CA, confirmed by surrogate date testing. The peak SI was transiently elevated during resistance breathing in the 60° position. Resistance breathing may transiently reduce CA efficiency. Paced breathing did not restore CO or ICA blood flow.

Pregabalin reduces opioid consumption and hyperalgesia but not pain intensity after laparoscopic donor nephrectomy

BACKGROUND

Gabapentinoids are increasingly used to reduce acute postoperative pain, opioid consumption and opioid-related adverse effects. We explored the opioid-sparing, analgesic and anti-hyperalgesic effect of perioperative administered pregabalin in laparoscopic living donor nephrectomy.

METHODS

In this randomized controlled trial, 80 patients were recruited and randomized to receive pregabalin 150 mg twice daily or placebo on the day of surgery and the first postoperative day as part of a multimodal analgesic regimen. Primary outcome was opioid consumption 0-48 h after surgery. Secondary outcomes were pain intensity at rest and with movement 0-48 h after surgery using the 0-10 Numeric Rating Scale and incisional hyperalgesia measured 24 h post-surgery and at hospital discharge. Further secondary outcomes were adverse effects. Persistent post-surgical pain was registered 6 weeks, 6 and 12 months after surgery.

RESULTS

Pregabalin significantly reduced opioid consumption compared with placebo 0-48 h after surgery (median mg [25th, 75th percentile]); 29.0 (22.0-45.5) vs. 41.8 (25.8-63.6) (P = 0.04). Pain intensity 0-48 h after surgery calculated as area under the pain (NRS) vs. time curve was not statistically different between groups at rest (P = 0.12) or with movement (P = 0.21). Pregabalin decreased incisional hyperalgesia 24 h after surgery (median cm [25th, 75th percentile] 8.5 (1.0-18.5) vs. 15.5 (9.5-24.0) (P = 0.02). Nausea (P ≤ 0.01), use of antiemetics (P ≤ 0.01) and pain-related sleep interference (P = 0.02) were reduced with pregabalin.

CONCLUSIONS

Perioperative pregabalin added to a multimodal analgesic regimen was opioid-sparing, but made no difference to pain intensity score 0-48 h after surgery. Pregabalin may reduce incisional hyperalgesia on the first day after surgery.

Chronic pain after breast augmentation is associated with both signs of peripheral nerve injury and central nervous mechanisms

Background/aims

The mechanisms behind chronic postsurgical pain remains unsettled. Quantitative sensory testing and questioning sensory function may help understand mechanisms behind the transition from acute to chronic pain. The aim of this study was to assess these aspects in postsurgical patients with and without chronic postsurgical pain.

Methods

116 women, who answered a questionnaire in a four years follow-up study of pain, sensory changes and quality of life after cosmetic breast augmentation surgery [1], were invited to participate in a psychophysical study. Twenty women answered the request and filled in a questionnaire, and 12 of these women finally met for examination.

Results

Six of the 12 women had pain in the area of surgery, three were pain-free, but reported sensory changes and three reported no pain or sensory disturbances. We performed a detailed quantitative sensory examination, with a protocol adapted from Rollke et al. [2] While only 3/6 patients in the pain-free group reported hypoesthesia, an area of hypoesthesia to tactile-, heat- and cold stimuli was identified in all subjects when examined (Table 1).

Table 1

The most striking difference between the group reporting pain and the one not reporting pain was the presence of paradoxical heat sensation, cold allodynia, abnormal temporal summation, and the presence of deep pain during/after pressure pain threshold testing with the algometer in the group with pain.

Conclusion

Self-reported sensory changes under-estimated sensory changes. Sensory testing revealed signs of peripheral nerve injury changes in all subjects, while signs of central nervous changes were found predominantly in patients with persistent pain.

Epidemiology of persistent postoperative pain: Association of persistent pain and sensory abnormalities

Background

The prevalence of persistent postoperative pain in the general population is poorly documented, but clinical studies indicate that the problem is common.

Aim

The aim of this study was (1) to assess the prevalence of persistent postoperative pain among individuals operated during the last 3 years in a general population and (2) to describe factors associated with chronic postoperative pain.

Materials and methods

As part of a cross-sectional health survey in the municipality of Tromsø, North Norway, all participants answered questions on surgery, persisting pain and sensory abnormalities in the area of surgery. N = 12,984. Age 30–87 years, median 59. 53.4% women.

Pain intensity was reported using a 0–10 Numeric Rating Scale (0–10 NRS). Logistic regression was used to reveal any associations between pain and self-reported hyposensitivity, hypersensitivity and allodynia.

Results

2316 individuals (17.8%) had surgery between 3 months and 3 years prior to the survey.

826 (40.4%)of the 2044 who answered a questionnaire on postsurgical pain, reported having some degree of pain in the area of surgery. Of these 826 individuals, 45.2% had pain, when at worst, of moderate or severe intensity, i.e. 0–10 NRS of 4 or higher.

The areas of surgery carrying the strongest association with persistent pain were (in descending order of frequency): (1) Shoulder/ upper arm [74.5% (108/145)], (2) back [73.9% (65/88)], (3) lungs [66.7% (8/12)], (4) knee/lower leg [63.7% (179/281)], (5) hand [58.8% (90/153)]. (6) hip/thigh [58.3% (74/127)] and (7) ankle/foot [58.7% (84/143)].

18.3% (413) had reduced sensitivity in the area near the surgical scar, while 10.6% (240) reported hypersensitivity and 5.6% (127) allodynia.

For those reporting hypoesthesia, the odds ratio (OR) for having pain was 2.71 (95% confidence interval 2.08–3.53), for those reporting hyperesthesia, OR was 4.82 (3.24–7.18) and for those with allodynia 5.83 (3.12–10.90).

Conclusions

3 months or more after surgery, nearly half of the respondents report having pain in the area of surgery. In this survey, there is a strong association between persistent pain and the presence of both hyposensitivity, hypersensitivity and allodynia.

Assessment of pain

Valid and reliable assessment of pain is essential for both clinical trials and effective pain management. The nature of pain makes objective measurement impossible. Acute pain can be reliably assessed, both at rest (important for comfort) and during movement (important for function and risk of postoperative complications), with one-dimensional tools such as numeric rating scales or visual analogue scales. Both these are more powerful in detecting changes in pain intensity than a verbal categorical rating scale. In acute pain trials, assessment of baseline pain must ensure sufficient pain intensity for the trial to detect meaningful treatment effects. Chronic pain assessment and its impact on physical, emotional, and social functions require multidimensional qualitative tools and health-related quality of life instruments. Several disease- and patient-specific functional scales are useful, such as the Western Ontario and MacMaster Universities for osteoarthritis, and several neuropathic pain screening tools. The Initiative on

METHODS

Measurement, and Pain Assessment in Clinical Trials recommendations for outcome measurements of chronic pain trials are also useful for routine assessment. Cancer pain assessment is complicated by a number of other bodily and mental symptoms such as fatigue and depression, all affecting quality of life. It is noteworthy that quality of life reported by chronic pain patients can be as much affected as that of terminal cancer patients. Any assessment of pain must take into account other factors, such as cognitive impairment or dementia, and assessment tools validated in the specific patient groups being studied.

Methylprednisolone and ketorolac rapidly reduce hyperalgesia around a skin burn injury and increase pressure pain thresholds

BACKGROUND

Glucocorticoids and non-steroidal anti-inflammatory drugs (NSAIDs) decrease acute postoperative pain and hyperalgesia. The objectives of this study were to investigate the effects of methylprednisolone and ketorolac on hyperalgesia around a skin burn injury and on pressure pain thresholds.

METHODS

In a double-blind, placebo-controlled, randomized trial with cross-over design, methylprednisolone 125 mg, ketorolac 60 mg or placebo was administered intravenously in 12 male volunteers on three separate days at least 4 days apart. Primary and secondary hyperalgesia were produced by a first-degree burn injury on abdominal skin 45 min before injection of the test medicines. The area of secondary mechanical hyperalgesia outside the site of injury was measured. Pressure pain stimuli were applied on the base of a fingernail, increasing until the pressure pain detection threshold (PPDT) and pressure pain tolerance threshold (PPTT) were reached.

RESULTS

Compared with placebo, the active drugs reduced the area of secondary hyperalgesia (methylprednisolone, P < 0.001; ketorolac, P < 0.01). Ketorolac but not methylprednisolone increased PPDT compared with placebo (P < 0.05). Both active drugs increased PPTT compared with placebo (methylprednisolone, P < 0.01; ketorolac, P < 0.001). Ketorolac increased PPTT more than methylprednisolone (P < 0.05).

CONCLUSIONS

Methylprednisolone and ketorolac increased PPTT attenuated secondary hyperalgesia around a skin burn injury. PPTT increased after both methylprednisolone and ketorolac. The present study demonstrates analgesic and anti-hyperalgesic properties of a glucocorticoid and a non-selective NSAID that have not been demonstrated previously in human subjects.

Methylprednisolone intravenously 1 day after surgery has sustained analgesic and opioid-sparing effects

BACKGROUND

In previous studies on glucocorticoids for postoperative pain, the test drug has been given perioperatively, usually before measurement of baseline pain. In order to evaluate the time course and magnitude of the analgesic effect of a glucocorticoid in well-established postoperative pain, we compared methylprednisolone with ketorolac and placebo, after assessment of baseline pain on the first postoperative day.

METHODS

This was a double-blind, single dose, randomized, parallel comparison of intravenous (i.v.) methylprednisolone 125 mg, ketorolac 30 mg as an active control, and placebo in 75 patients with moderate to severe pain 1 day after orthopaedic surgery. Outcome variables were pain intensity (0-100 VAS), pain relief (0-4 PAR) and rescue opioid consumption.

RESULTS

Methylprednisolone was not significantly different from ketorolac and gave significantly lower pain intensity from 1 h (0-6 h, P < 0.02), and more pain relief 2-6 h after test drugs (P < 0.05) compared with placebo. After 24 h, pain intensity was lower in both active drug groups compared with placebo (methylprednisolone, P < 0.0001; ketorolac, P < 0.007). Number needed to treat (NNT) calculated from patients having more than at least 50% of maximum obtainable total pain relief during the first 6 h (>50%maxTOTPAR(6 h)) was 3.6 for methylprednisolone and 3.1 for ketorolac. Number needed to treat calculated from the percentage reporting at least 50% pain relief for at least 4 h (>50%PAR(4 h)) was 2.8 for both groups. Opioid consumption was significantly reduced for 72 h after methylprednisolone compared with ketorolac (P < 0.02) and placebo (P < 0.003).

CONCLUSION

Methylprednisolone 125 mg i.v. 1 day after surgery gave similar early reduction of pain as i.v. ketorolac 30 mg. Less pain than placebo 24 h after methylprednisolone, and lower opioid consumption for 72 h compared with ketorolac and placebo indicate sustained analgesic effects of methylprednisolone.