Incidence of serotonin syndrome in patients treated with fentanyl on serotonergic agents.

BACKGROUND: There has been a recent surge in the literature highlighting the association of fentanyl as precipitating serotonin syndrome in patients on a serotonergic agent. OBJECTIVE: The purpose of our study was to understand the incidence of serotonin syndrome in patients who receive fentanyl while on serotonergic agents. STUDY DESIGN: This retrospective analysis was conducted from 2012 to 2013 after approval from the Institutional Review Board. We searched for all patients that had received a serotonergic agent and were admitted to the hospital during the study period. Next, we split these patients into 2 groups by placing all patients who had received fentanyl and a serotonergic agent into one group. We then searched for any of the Hunter Serotonin Toxicity Criteria in the records of patients that had received both fentanyl and a serotonergic agent. Further, we searched for all patients with serotonin syndrome mentioned in their records. SETTING: This study was conducted at a 900 bed tertiary care academic center. RESULTS: Over the 2 year study period, 112,045 patients were on a serotonergic agent, and 4,538 of these patients were treated with both fentanyl and a serotonergic agent. A search for Hunter's Criteria through the records of the patients receiving both fentanyl and a serotonergic agent revealed 23 patients had been documented with some of these symptoms. On detailed chart review, only 4 [95% CI 1 - 10] of these patients truly met Hunter's Criteria for serotonin syndrome. We then searched all admissions for a diagnosis code of serotonin syndrome during the study period. Five additional cases of serotonin syndrome were found, but none of these patients were treated with fentanyl. LIMITATIONS: Some of the limitations of our study include that it represents a single institution, although it is a large academic center. An inherent limitation may be the under diagnosis of serotonin syndrome. CONCLUSION: The incidence of serotonin syndrome in patients who receive both fentanyl and a serotonergic agent is low.

Use of targeted transversus abdominus plane blocks in pediatric patients with anterior cutaneous nerve entrapment syndrome.

Anterior cutaneous nerve entrapment syndrome (ACNES) is a commonly overlooked source of chronic abdominal wall pain. A diagnosis of ACNES should be considered in cases of severe, localized abdominal pain that is accentuated by physical activity. Providers should consider diagnosing ACNES once a patient has both a positive result from a Carnett's test and precise localization of pain. We describe the use of transversus abdominus plane (TAP) blocks to treat ACNES in the pediatric patient population. TAP blocks are a treatment modality which have been described less frequently in the management of this syndrome, with rectus sheath blocks being used more commonly. TAP blocks can be used effectively for ACNES by targeting the site of maximal tenderness, which was identified using ultrasound guidance. Moreover, TAP blocks are an attractive procedure option for ACNES as they are less invasive than other commonly used techniques. We present 3 case series reports of pediatric patients evaluated at our institution for severe abdominal pain to describe the clinical manifestations, sequelae, and outcome of ACNES. Though the exact incidence of ACNES in the pediatric population is unknown, this condition has significant implications from chronic pain. Chronic pain can lead to significant emotional and social impacts on these pediatric patients, as well as their on their families. Further, the extensive utilization of health care resources is impacted when children with undiagnosed ACNES undergo invasive treatments when ACNES is not in the early differential. The purpose of this case series report is to prompt better recognition of the condition ACNES, and to highlight the efficacy of TAP blocks as a management strategy.

Elevated lidocaine serum levels following the use of a needle free device in healthy adult volunteers.

There is increased concern regarding circulating levels of lidocaine immediately after the use of a needle-free device with buffered lidocaine. As a result, we conducted a prospective study to assess lidocaine circulation after the use of a needle-free device for the delivery of a local anesthetic in 10 healthy adult subjects. After informed consent, 2 peripheral intravenous catheters were placed in the antecubital fossa of each arm. Two milligrams of 1% buffered lidocaine was administered by the study physician via the needle-free device on the dorsum of the subject's hand. Within 2 minutes, a third intravenous catheter was placed in the location of the lidocaine administration and 5 mL of blood was collected from all 3 sites. If blood samples returned positive for lidocaine, they were also collected 1 hour and 2 hours after administration. Toxic levels of lidocaine were found in blood drawn from 2 subjects immediately after lidocaine administration. Results also showed that certain subjects had increasing levels of lidocaine over time. Other subjects also had increasing lidocaine serum levels from blood drawn on the arm opposite the administration site. We concluded that there may be systemic lidocaine levels with the administration of the needle-free device and that these levels may reach the toxic range in adults. Further investigation will be required to determine whether this finding has clinical significance, especially considering the smaller body mass of children.

Intrathecal Drug Delivery (ITDD) systems for cancer pain.

Intrathecal drug delivery is an effective pain management option for patients with chronic and cancer pain. The delivery of drugs into the intrathecal space provides superior analgesia with smaller doses of analgesics to minimize side effects while significantly improving quality of life. This article aims to provide a general overview of the use of intrathecal drug delivery to manage pain, dosing recommendations, potential risks and complications, and growing trends in the field.