Rapid opioid dose escalation, possibly caused by tolerance, has been observed in some patients on daily opioid therapy, although clinically identifiable characteristics of these patients are unknown. In this retrospective chart review of 206 patients, we examined whether the age of the patient was related to opioid escalation. Initial starting doses of long-acting opioids were similar in younger patients (< or =50 yr; 49 +/- 3 mg/d oral morphine-equivalent dose) versus older patients (> or =60 yr; 42 +/- 3 mg/d). Younger patients reached a maximum dose of 452 +/- 63 mg/d over 15.0 +/- 1.3 mo, whereas older patients achieved a maximum dose of 211 +/- 23 mg/d over 14.4 +/- 1.5 mo (P < 0.0001). At the last clinic visit, younger-patient dosing averaged 365 +/- 61 mg/d, with older patients averaging 168 +/- 18 mg/d (P < 0.0001). Only older patients demonstrated a reduction in visual analog scale scores from start of opioid therapy until discharge from the clinic (6.9 +/- 0.3 to 5.6 +/- 0.3; P < 0.01). These clinical data suggest that age is an important variable in opioid dose escalation. Although factors other than opioid tolerance can result in dose escalation, it is possible that older patients may have a reduced rate of tolerance development.

No abstract

In all age groups, the use of opioids to treat chronic pain conditions has increased, yet the impact of age on opioid tolerance development has not been comprehensively addressed. In this study, we investigated age-related differences in morphine tolerance development in rats. Rats aged 3 wk, 3 mo, 6 mo, and 1 yr were used in the study. Morphine (8 mg/kg) was injected subcutaneously twice each day and its analgesic effect assessed by the change in tail-flick latency using a thermal stimulus 5 min before and 30 min after dosing. Tolerance was defined as a 75% reduction in morphine-induced analgesia compared to Day 1. Rats aged 3 wk, 3 mo, 6 mo, and 1 yr developed tolerance on the 4th, 10th, 14th, and 22nd days of morphine treatment, respectively. Plasma levels of morphine and its metabolites showed that pharmacokinetic differences among the groups did not correlate with the differences in tolerance development. This study demonstrates that morphine tolerance occurs more rapidly in younger rats than older rats and is unlikely to be the result of differences in drug metabolism or clearance. Aging may impact molecular processes involved in tolerance development and provide insight into novel therapeutic targets to delay opioid tolerance development.

PurposeChronic pain after cesarean section (CS) is a serious concern, as it can result in functional disability. We evaluated the prevalence of chronic pain after CS prospectively at a single institution in Japan. We also analyzed perioperative risk factors associated with chronic pain using logistic regression analyses with a backward-stepwise procedure.Materials and MethodsPatients who underwent elective or emergency CS between May 2012 and May 2014 were recruited. Maternal demographics as well as details of surgery and anesthesia were recorded. An anesthesiologist visited the patients on postoperative day (POD) 1 and 2, and assessed their pain with the Prince Henry Pain Scale. To evaluate the prevalence of chronic pain, we contacted patients by sending a questionnaire 3 months post-CS.ResultsAmong 225 patients who questionnaires, 69 (30.7%) of patients complained of persistent pain, although no patient required pain medication. Multivariate analyses identified lighter weight (p = 0.011) and non-intrathecal administration of morphine (p = 0.023) as determinant factors associated with persistent pain at 3 months. The adjusted odds ratio of intrathecal administration of morphine to reduce persistent pain was 0.424, suggesting that intrathecal administration of morphine could decrease chronic pain by 50%. In addition, 51.6% of patients had abnormal wound sensation, suggesting the development of neuropathic pain. Also, 6% of patients with abnormal wound sensation required medication, yet no patients with persistent pain required medication.ConclusionAlthough no effect on acute pain was observed, intrathecal administration of morphine significantly decreased chronic pain after CS.

BackgroundDexamethasone added to local anesthetic for brachial plexus block improves postoperative pain after arthroscopic rotator cuff repair, as compared with the use of local anesthetic alone. Dexamethasone is present in non-particulate form in local anesthetic solution, while betamethasone is partially present in particulate form. The particulate betamethasone gradually decays and is expected to cause its longer-lasting effect. This study investigated the postoperative analgesic effect of betamethasone added to ropivacaine for brachial plexus block in patients who underwent arthroscopic rotator cuff repair.MethodsThis was a prospective, randomized, triple-blind study of 44 patients undergoing arthroscopic rotator cuff repair surgery. Ultrasound-guided interscalene brachial plexus block, involving 20 mL of 0.375 % ropivacaine (group R) or 19 mL of 0.375 % ropivacaine with 4 mg (1 mL) of betamethasone (group BR), was administered and surgery was performed under general anesthesia. After surgery, the pain score was recorded at 12 h after surgery, and on the first, second, and seventh postoperative day. Analgesia duration, offset time of motor block, frequency of rescue analgesic administration, postoperative nausea/vomiting, and sleep disturbance during the night after surgery were recorded. The numerical values were expressed as median [interquartile range]. P values < 0.05 were considered statistically significant.ResultsThe duration of analgesia was significantly prolonged in group BR (group BR: 19.1 h [16.6, 20.9 h], group R: 13.3 h [11.6, 16.5 h], p < 0.001). The pain scores at 12 h after surgery and on the first and seventh day after surgery were significantly lower in group BR than in group R. The duration of motor block was significantly prolonged in group BR. The frequency of rescue analgesic administration and the sleep disturbance rate were significantly lower in group BR. There was no difference in postoperative nausea/vomiting between the two groups.ConclusionsBetamethasone added to local anesthetic in interscalene brachial plexus block improved postoperative pain after arthroscopic rotator cuff repair, and betamethasone prolonged the duration of analgesia by almost 6 h.Trial registrationUniversity Hospital Medical Information Network Center Clinical Trials Registration System (UMIN000012899).Electronic supplementary materialThe online version of this article (doi:10.1186/s12871-016-0251-9) contains supplementary material, which is available to authorized users.

The short-axis out-of-plane approach (SAX-OOP) is commonly used in ultrasound-guided internal jugular vein catheterization. However, this approach has a risk of posterior vein wall injuries. The authors hypothesized that a shallow angle of approach may reduce the rate of posterior wall injuries compared with the conventional steep angle approach. The present study aimed to evaluate whether a difference in the angle of approach of the needle affects the rate of posterior wall injuries. The present study was a randomized crossover-controlled trial involving 40 medical residents, conducted in the clinical training center at a hospital with a residency program. The primary outcome measure was the rate of posterior vessel wall injuries. Subjects received a didactic lecture during which the instructors taught three SAX-OOP techniques including the conventional free-hand method (procedure C), a needle navigation system (procedure N), and a shallow puncture angle using a guidance system (procedure S). Participants were trained in these approaches under supervision and each technique tested in a simulation environment. Thirty-four of 40 residents had no previous experience with central venous catheterization and were included in the final analysis. The rate of posterior vessel wall injuries in procedure S (9%) was significantly lower than using the other approaches (procedure C, 53%; procedure N, 41%). In conclusion, a shallow angle of approach using the SAX-OOP technique resulted in significantly fewer posterior vein wall injuries in central venous catheterization compared with steep angle techniques.

Introduction:Atherosclerosis has a complex etiology that leads to arterial obstruction and often results in inadequate perfusion of the distal limbs. Patients with atherosclerosis can have severe complications of this condition, with widespread systemic manifestations, and the operations undertaken are often challenging for anesthesiologists.Case report:A 79-year-old woman with chronic heart failure and respiratory dysfunction presented with bilateral gangrene of the distal lower extremities with obstruction of the left common iliac artery due to atherosclerosis. Femoral–femoral bypass graft and bilateral foot amputations were planned. Spinal anesthesia failed due to severe scoliosis and deformed vertebrae. General anesthesia was induced after performing multiple nerve blocks including quadratus lumborum, sciatic nerve, femoral nerve, lateral femoral cutaneous nerve, and obturator nerve blocks. However, general anesthesia was abandoned because of deterioration in systemic perfusion. The surgery was completed; the patient remained comfortable and awake without the need for further analgesics.Conclusion:Quadratus lumborum block may be a useful anesthetic technique to perform femoral–femoral bypass.

No abstract