Adjuvant Agents in Regional Anesthesia in the Ambulatory Setting

Purpose of Review

A majority of surgical practice has involved ambulatory centers with the number of outpatient operations in the USA doubling to 26.8 million per year. Local anesthesia delivery provides numerous benefits, including increased satisfaction, earlier discharge, and reduction in unplanned hospital admission. Further, with the epidemic of opioid mediated overdoses, local anesthesia can be a key tool in providing an opportunity to reduce the need for other analgesics postoperatively.

Recent Findings

Adjuvants such as epinephrine and clonidine enhance local anesthetic clinical utility. Further, dexmedetomidine prolongs regional blockade duration effects. There has also been a significant interest recently in the use of dexamethasone. Studies have demonstrated a significant prolongation in motor and sensory block with perineural dexamethasone. Findings are conflicting as to whether intravenous dexamethasone has similar beneficial effects. However, considering the possible neurotoxicity effects, which perineural dexamethasone may present, it would be prudent not to consider intravenously administered dexamethasone to prolong regional block duration. Many studies have also demonstrated neurotoxicity from intrathecally administered midazolam. Therefore, midazolam as an adjuvant is not recommended. Magnesium prolongs regional block duration but related to paucity of studies as of yet, cannot be recommended. Tramadol yields inconsistent results and ketamine is associated with psychotomimetic adverse effects. Buprenorphine consistently increases regional block duration and reduce opioid requirements by a significant amount. Future studies are warranted to define best practice strategies for these adjuvant agents.

Summary

The present review focuses on the many roles of local anesthetics in current ambulatory practice.

     

Neurogenic thoracic outlet syndrome: A case report and review of the literature

Neurogenic thoracic outlet syndrome (NTOS) is an oft-overlooked and obscure cause of shoulder pain, which regularly presents to the office of shoulder surgeons and pain specialist. With this paper we present an otherwise healthy young female patient with typical NTOS. She first received repeated conservative treatments with 60 units of botulinium toxin injected into the anterior scalene muscle at three-month intervals, which providing excellent results of symptom-free periods. Later a trans-axillary first rib resection provided semi-permanent relief. The patient was followed for 10 years after which time the symptoms reappeared. We review the literature and elaborate on the anatomy, sonoanatomy, etiology and characteristics, symptoms, diagnostic criteria and treatment modalities of NTOS. Patients with NTOS often get operated upon - even if just a diagnostic arthroscopy, and an interscalene or other brachial plexus block may be performed. This might put the patient in jeopardy of permanent nerve injury, and the purpose of this review is to minimize or prevent this.     

A Case Series of HIV-Seropositive Patients and Hypercoagulable State—Is It Difficult to Treat Even with Therapeutic Anticoagulation?

Patients with human immunodeficiency virus (HIV) are at risk of developing thrombosis and are 8 to 10 times more likely to develop thrombosis than the general population. Moreover, if they have hypercoagulable state they can have severe thrombosis and life-threatening thrombotic events. The purpose of this retrospective study is to analyze hypercoagulable state in HIV-seropositive patients who have been diagnosed with venous thromboembolism (VTE). This study is a subgroup study of a larger cohort group of HIV-seropositive patients with VTE followed up with our vascular medicine outpatient clinic. The patients included for this study were HIV-seropositive patients with hypercoagulable state, analyzed over the past 3 years, and followed prospectively. HIV-seropositive patients with arterial thrombosis were excluded. These patients had minimum, regular follow-up of 3 months, with a Doppler scan in the beginning and last follow-up. All the patients were analyzed for hypercoagulable state and the patients selected in this study were those who were tested positive for hypercoagulable state. All patients were analyzed for age, gender, race, site of thrombosis, coagulation factors, lipid panel, type of antiretroviral treatment, past or present history of infections or malignancy, CD4 absolute and helper cell counts at the beginning of thrombosis, and response to treatment and outcome. Patients with HIV with arterial thrombosis were excluded. The study was approved by the ethics committee. Five patients were included in this study. The mean age was 47.8 years (range 38 to 58 years). All were male patients with lower limb thrombosis. Most common venous thrombosis was popliteal vein thrombosis, followed by common femoral, superficial femoral, and external iliac thrombosis. Two patients had deficiency of protein S, two had high homocysteine levels, one had deficiency of antithrombin 3, and one had increase in anticardiolipin immunoglobulin G antibody. All the patients were taking nucleoside and nonnucleoside inhibitors but only one patient was taking protease inhibitors. There was no history of malignancy but two patients had past history of tuberculosis. The mean absolute CD4 counts were 244 cells/UL (range 103 to 392 cells/UL) and helper CD4 counts were 19.6 cells/UL (range 15 to 30 cells/UL). All were anticoagulated with warfarin or enoxaparin. There was complete resolution of deep vein thrombosis only in one patient on long-term anticoagulation but there was no resolution of thrombosis in the other four patients despite of therapeutic anticoagulation for more than 6 months. All the patients are alive and on regular follow-up. Thrombosis in HIV patients is seen more commonly in middle aged, community ambulant male patients. The most common hypercoagulable state was noted as deficiency of protein S and hyperhomocysteinemia. Eighty percent of the patients did not respond to therapeutic anticoagulation.     

Disseminated intravascular coagulation complicating urothelial malignancy

Transitional cell carcinoma has rarely been reported to be associated with disseminated intravascular coagulation (DIC). We report a 55-year-old Chinese man who was diagnosed with transitional cell carcinoma with vertebral metastasis. He presented with severe anaemia and thrombocytopenia, and subsequent evaluation revealed features of DIC. Interestingly, he did not have fever, any localising symptoms or signs of infection. He was treated aggressively with transfusion of packed cells, platelets, intravenous vitamin K and fresh frozen plasma. Despite aggressive treatment, the coagulation abnormalities were resistant to correction. The patient continued to deteriorate and eventually died of cardiac arrest. This case illustrates that transitional cell carcinoma can also be associated with DIC, possibly due to the expression of certain unidentified procoagulant factors similar to the tissue factor responsible for DIC.     

Lemierre Syndrome—Should We Anticoagulate? A Case Report and Review of the Literature

Lemierre syndrome is an uncommon condition classically described in acute oropharyngeal infection with septic thrombophlebitis of the internal jugular vein and metastatic septic embolism particularly to the lungs. It is commonly described in young healthy adults with isolation of Fusobacterium necrophorum. We describe a case of Lemierre syndrome in a 50-year-old man with newly diagnosed diabetes mellitus presenting with a neck abscess secondary to Klebsiella pneumoniae. Our patient made good recovery to appropriate antimicrobial therapy, prompt surgical drainage, and anticoagulation. Anticoagulation remains controversial and we review the literature for its role in Lemierre syndrome.     

Risk of Venous Thromboembolism in Patients Infected with HIV: A Cohort Study

Introduction Human immunodeficiency virus (HIV) patients are at risk of developing thrombosis than general population. There are several intersecting mechanisms associated with HIV infection and antiviral therapy that are emerging, which may lead to vasculopathy and hypercoagulability in these patients.Methods We analyzed the HIV patients who followed up with our Vascular Medicine outpatient clinic with venous thromboembolism (VTE) over the past 3 years and followed them prospectively. The patients included were those who had minimum, regular follow-up of 3 months, with a Doppler scan in the beginning and last follow-up. Patients were analyzed for age, gender, race, site of thrombosis, coagulation factors, lipid panel, type of antiretroviral treatment, past or present history of infections or malignancy, CD4 absolute and helper cell counts at the beginning of thrombosis, response to treatment and outcome. Patients with HIV with arterial thrombosis were excluded.Results A total of eight patients were analyzed. The mean age was 49.87 years (range, 38-58 years). All were male patients with six patients having lower limb thrombosis, one patient with upper limb thrombosis related to peripheral inserted central catheter (PICC), and one patient had pulmonary embolism with no deep vein thrombosis. Most common venous thrombosis was popliteal vein thrombosis, followed by common femoral, superficial femoral and external iliac thrombosis. Two patients had deficiency of protein S, two had high homocysteine levels, one had deficiency of antithrombin 3, and one had increase in anticardiolipin Immunoglobulin antibody. All patients were taking nucleoside and nonnucleoside inhibitors but only two patients were taking protease inhibitors. There was history of lymphoma in one and nonsmall cell lung carcinoma in one patient. Three patients had past history of tuberculosis and one of these patients also had pneumocystis carinii pneumonia. The mean absolute CD4 counts were 383.25 cells/UL (range, 103-908 cells/UL) and helper CD4 counts were 22.5 cells/UL (range, 12-45 cells/UL). All were anticoagulated with warfarin or enoxaparin. There was complete resolution of deep vein thrombosis in two patients (one with PICC line thrombosis in 3 months and other with popliteal vein thrombosis in 1 year). There was extension of clot in one patient and no resolution in others. Seven patients are still alive and on regular follow-up.Conclusion Thrombosis in HIV patients is seen more commonly in middle aged, community ambulant male patients. Left lower limb involvement with involvement of popliteal vein is most common. Deficiency of protein S and hyperhomocystenaemia were noted in these patients. Most of these patients did not respond to therapeutic anticoagulation, but the extension of the thrombosis was prevented in majority of cases.     

Efficacy and safety of a pharmacist-managed inpatient anticoagulation service for warfarin initiation and titration

What is known and Objective: Anticoagulation consultations provided by a pharmacist‐staffed inpatient service, similar to the experience reported in outpatient anticoagulation clinics, can potentially improve anticoagulation control and outcomes. At Tan Tock Seng Hospital, a 1200‐bed acute care teaching hospital in Singapore, pharmacist‐managed anticoagulation clinics have been in place since 1997. Pharmacist‐managed services were extended to inpatient consultations in anticoagulation management from April 2006. Our objective was to assess the effect of implementing a pharmacist‐managed inpatient anticoagulation service. Methods: This was a single‐centre cohort study. Baseline data from 1 January 2006 to 31 March 2006 were collected and compared with post‐implementation data from 1 April 2006 to 31 March 2007. Patients newly started on warfarin for deep vein thrombosis, pulmonary embolism or atrial fibrillation in general medicine and surgery departments were included. The three endpoints were as follows: (i) percentage of international normalized ratios (INRs) achieving therapeutic range within 5 days, (ii) INRs more than 4 during titration and (iii) subtherapeutic INRs on discharge. Results and Discussion: A total of 26 patients in the control period were compared with 144 patients who had received dosing consultations by a pharmacist during the initiation of warfarin. The provision of pharmacist consult resulted in 88% compared to 38% (P < 0·001) of INR values achieving therapeutic range within 5 days. There was a reduction in INR values of more than 4 during titration from 27% to 2% (P < 0·001), and subtherapeutic INR values on discharge without low molecular weight heparin from 15% to 0% (P < 0·001). The mean time to therapeutic INR was reduced from 6·5 to 3·9 days (P < 0·001) and mean length of stay after initiation of warfarin from 11 to 7·7 days (P = 0·004). What is new and Conclusion: Inpatient anticoagulation care and outcomes were significantly improved by a pharmacist‐managed anticoagulation service. The time to therapeutic INR was achieved appropriately and efficiently without compromising patient’s safety.     

Vascular Arterial Compression Syndromes

Vascular arterial compression syndromes are uncommon disorders due to dynamic anatomic compression of an artery resulting in significant ischemia in the supplied territories with ensuing symptoms. The diagnosis of these disorders requires heightened awareness and a high index of suspicion by the clinician. These diagnoses should be particularly suspected in young patients with typical symptoms but without underlying cardiovascular risk factors. Physical examination may be unremarkable, although the clinical symptoms or signs may be elicited with provocative maneuvers. The diagnostic work-up may include noninvasive tests such as Doppler waveforms, duplex ultrasonography, computed tomographic angiography, and MRI/angiography, but may require conventional angiogram for confirmation or treatment planning. Although provocative maneuvers may indicate arterial compression in symptomatic patients, it is important to note that these maneuvers may also be positive in normal asymptomatic subjects. These disorders are typically treated surgically with procedures leading to decompression, but anticoagulation, thrombolytic therapy, and even surgical bypass operations may be needed for arterial occlusions.