Plasma Ropivacaine Concentrations Following Local Infiltration Analgesia in Total Knee Arthroplasty: A Pharmacokinetic Study to Determine Safety Following Fixed-Dose Administration

Background and Objectives The primary aim of this study was to examine the pharmacokinetics of ropivacaine in patients undergoing elective total knee arthroplasty with local infiltration analgesia as the primary analgesic method. We also sought to determine the incidence of biochemical toxicity through measurement of plasma ropivacaine concentrations over the first 24 hours postoperatively. Methods This was a prospective, observational study of 15 patients undergoing elective total knee arthroplasty. Local infiltration analgesia was administered by standard technique with 300 mg ropivacaine and epinephrine 5 μg/mL. Total ropivacaine concentrations were taken at specified time intervals in the 24 hours after tourniquet release and analyzed by liquid chromatography–mass spectrometry. Results Fifteen patients were enrolled into the study. The median peak ropivacaine concentration was 0.57 μg/mL, with a range of 0.32 to 0.88 μg/mL, and occurred between 6 and 24 hours. Age (P = 0.04), weight (P = 0.04), creatinine (P = 0.02), and female sex (P = 0.03) were important predictors of peak concentration. Age (P = 0.02), female sex (P = 0.01), and baseline α1 acid glycoprotein concentrations (P = 0.03) were important predictors for the area under the curve from a ropivacaine concentration versus time plot. Conclusions The peak total ropivacaine concentration was below quoted toxic concentrations (2.2 μg/mL) in all patients. This peak occurred later than has previously been described in those undergoing neuraxial or peripheral nerve block, occurring between 6 and 24 hours. The influence of age, weight, and renal function on systemic ropivacaine concentration should be considered when planning local infiltration analgesia. Female sex is a factor that has not previously been associated with peak ropivacaine concentrations. Accepted for publication August 28, 2017. Address correspondence to: Reuben J. Miller, MBChB, Department of Anaesthesia and Pain Medicine, Middlemore Hospital, Private Bag 93311, Otahuhu, Auckland 1640, New Zealand (e-mail: reuben.j.miller@gmail.com). The authors declare no conflict of interest. This research was funded in part by the Counties Manukau Health TUPU fund and the South Auckland Anaesthetic Research Trust. Copyright © 2018 by American Society of Regional Anesthesia and Pain Medicine.

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Epidural Hematoma Following Cessation of a Direct Oral Anticoagulant: A Case Report

Objective In this case report, we describe a case of epidural hematoma following epidural analgesia in a patient with recent cessation of a direct oral anticoagulant (DOAC). Case Report An 89-year-old woman requiring upper abdominal surgery presented with multiple comorbidities, including a prior cerebrovascular accident resulting in a left-sided hemiparesis and atrial fibrillation requiring anticoagulation with rivaroxaban. In accordance with our departmental guidelines at the time of procedure, rivaroxaban was discontinued 4 days preoperatively. A thoracic epidural was placed at T8/9 immediately prior to induction. Venous thromboembolism prophylaxis was provided with compression devices, and every-12-hour unfractionated heparin initiated 5.5 hours after epidural placement. On postoperative day 2, the patient was noted to have a bilateral motor block, and imaging demonstrated a thoracic epidural hematoma extending from T6 to T11. Preexisting neurological deficits may have delayed detection. With patient agreement, neurosurgery recommended observation rather than surgical decompression because the patient was a poor surgical candidate and limited neurologic recovery was expected. The patient had modest motor recovery over the next few months. Conclusions Guidelines for cessation of DOACs prior to neuraxial techniques are based on pharmacologic half-lives rather than accumulated experience. This case adds to the experience of neuraxial analgesia complications while following these guidelines. Patient risk may be increased by the combination of recent cessation of a DOAC, as well as the cumulative effect of multiple small risk factors. Continued vigilance and reporting of cases of epidural hematomas will enhance our understanding and ultimately improve patient care. Elderly patients and/or patients with prior neurological deficits may present further challenges for early detection and require frequent assessments with comparison to baseline status. Accepted for publication October 4, 2017. Address correspondence to: Melanie Jaeger, MD, FRCPC, Department of Anesthesiology and Perioperative Medicine, Queen's University, Victory 2, Kingston General Hospital, 76 Stuart St, Kingston, Ontario, Canada, K7L 2V7 (e-mail: jaegerm@kgh.kari.net). No funding was acquired for preparation or publication of this article. The authors declare no conflict of interest. Copyright © 2018 by American Society of Regional Anesthesia and Pain Medicine.

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Case of psoriatic arthritis mutilans whose finger dysfunction was successfully ameliorated by surgical intervention during infliximab treatment

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Impact of a new simplified disability scoring system for adult patients with localized scleroderma

Abstract

Localized scleroderma (LoS) involves dermal but not internal inflammation and fibrosis. Cosmetic changes often impact quality of life (QOL), however, impairment of activities of daily living (ADL) in LoS patients has not been investigated. To determine what factor(s) are associated with ADL in adult patients with LoS, we performed a retrospective observational study in 177 Japanese adult LoS patients using a novel LoS disability score based on Barthel's indices of ADL: feeding, bathing, grooming, dressing, bowels, bladder, toilet use, transfers, mobility and stairs. LoS disability scores increased in proportion to the number of affected body parts but were not correlated to age and duration of illness. The presence of leg lesions significantly impaired ADL of LoS patients compared with lesions on other body parts. Patients treated with systemic medications, who tended to have multiple lesions, presented higher LoS disability scores than those without systemic treatments. Our study proposes that physicians evaluate ADL, not only QOL, in LoS patients. Our findings using LoS disability scoring indicate that multiple affected body parts and leg lesions are risk factors for ADL impairment.

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Current developments in phototherapy for psoriasis

Abstract

Phototherapy utilizes the beneficial effects of ultraviolet (UV) wavelengths to affect immunoregulatory functions. UV light phototherapy using narrowband UV-B (NB-UVB) and bath-psoralen UV-A (bath-PUVA) therapy are well-established treatments for psoriasis. Dual-action mechanisms of UV phototherapy have been identified: apoptosis and immune suppression. NB-UVB depletes pathogenic T cells by inducing apoptosis and regulatory T cells. Other wavelengths are also utilized for phototherapy, namely 308-nm excimer light and 312-nm flat-typed NB-UVB. Excimer light (308-nm) therapy effectively targets the affected skin without unduly exposing other areas and increases the levels of regulatory T cells. Phototherapy improves impaired resting regulatory T cells and increases activated regulatory T cells in patients with psoriasis. Intensive studies of phototherapy effects have led to several improvements in the design, protocols, and light sources, such as UV light-emitting diodes, thereby providing several options for patients with refractory skin disease, such as psoriasis.

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Case with anaphylactic shock induced by heparin-lock flush injection

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Birth Order and Pediatric Allergic Disease: A Nationwide Longitudinal Survey

Abstract

Background

Environmental factors seem to be related to the incidence of allergic disease. Children with a later birth order are often exposed to environments where pathogens and endotoxins can be found, and thus have a higher risk of developing infectious diseases. Therefore, birth order is regarded as an indicator that reflects postnatal environment. However, longitudinal studies are limited on this subject. This study sought to elucidate the relationships between birth order and allergic disease.

Methods

From a nationwide longitudinal study that followed children born in 2001 (n=47,015), we selected doctors' visits for three types of allergic disease—bronchial asthma, food allergy, and atopic dermatitis—from infancy to 12 years of age and conducted binomial log-linear regression analysis to evaluate the associations between birth order and these diseases. We adjusted for child and parental factors and estimated risk ratio (RR) and 95% confidence interval (CI) for each outcome.

Results

The associations between birth order and bronchial asthma were diverse; later birth order increased the risk in early childhood, but decreased the risks during school age. For example, the adjusted RR comparing third-born or higher and first-born children was 1.19 (95% CI, 1.05 to 1.35) between 30 and 42 months of age, but was 0.76 (95% CI, 0.65 to 0.89) between 10 and 11 years. Later birth order was generally protective for food allergy but increased the risk of atopic dermatitis.

Conclusion

The influence of birth order depended on the type of allergic disease and the childhood period. Childhood is unique in terms of physical and immunological development, and the immune response to the postnatal environment in childhood appears to be heterogeneous.

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