Peripheral nerve block adjuncts: which medication to choose? A narrative review of the current literature.

Enhancing the effect of peripheral nerve blockade by adding other classes of medications has long history of trial and error. Studies have identified multiple potentially beneficial adjuncts that work to either speed the onset of analgesia or prolong its duration. The benefits of these adjuncts must be weighed against the risks of systemic negative side effects. To date, the most commonly used adjuncts, and ones with the most robust scientific efficacy are, dexamethasone, dexmedetomidine and buprenorphine. This narrative review will discuss several classes of local anesthetic adjuncts and provide evidence for the clinical efficacy and side effect profile of the most commonly studied medications.

Opioid maintenance, weaning and detoxification techniques; where we have been, where we are now and what the future holds: an update.

In 2017, the US Department of Health and Human Services declared a public health emergency on the opioid crisis. On average, 115 Americans die each day from an opioid overdose. The scope and breadth of this problem is continually evolving. In 2010, there was a shift in causes primarily due to the use of heroin, and currently the latest shift in opioid-related deaths involves a variety of synthetic opioids, particularly illicitly manufactured fentanyl. As the medical, sociological and political environments have drastically changed, especially in the USA, over the last 6 years with regard to opioid use and misuse, an updated review of the literature was necessary.

The feasibility of employing a home healthcare model for education and treatment of opioid overdose using a naloxone auto-injector in a private practice pain medicine clinic.

OBJECTIVES: The purpose of this study was to determine if employing a home healthcare model for education and treatment of opioid overdose using the Evzio (Naloxone) auto-injector in a private practice pain clinic. METHODS: A prospective survey was used to determine the feasibility of integrating a naloxone auto-injector within the patient's home with a home care training model. Twenty moderate or high-risk patients were enrolled from the chronic pain clinic. Patients who were moderate or high risk completed an evaluation survey. The naloxone auto-injector was dispensed to all patients meeting criteria. The treating provider after prescribing the naloxone auto-injector then consulted home health per standard clinical practice. All patients had home health consulted to perform overdose identification and rescue training. A Cochran's Q test was conducted to examine differences in patient knowledge pre- and post-training. The post training test was done 2-4 weeks later. RESULTS: Forty subjects enrolled after meeting inclusion/exclusion criteria. Twenty withdrew because their insurance declined coverage for the naloxone auto-injector. Those completing home health showed a statistically significant difference in their ability to correctly identify the steps needed to effectively respond to an overdose (p = .03). DISCUSSION: Preliminary evidence would suggest training on overdose symptom recognition and proper use of prescription naloxone for treatment in the home setting by home health staff would prove more beneficial than the clinic setting, but feasibility was hindered by unaffordable costs related to insurance coverage limitations.

An observational feasibility study to assess the safety and effectiveness of intranasal fentanyl for radiofrequency ablations of the lumbar facet joints.

PURPOSE: The purpose of the present observational, feasibility study is to assess the preliminary safety and effectiveness of intranasal fentanyl for lumbar facet radiofrequency ablation procedures. PATIENTS AND METHODS: This cohort observational study included 23 adult patients. Systolic and diastolic blood pressures, heart rate, oxygen saturation percent, Pasero Opioid-Induced Sedation Scale score, and the Defense and Veterans Pain Rating Scale pain score were assessed prior to the procedure and intranasal fentanyl (100 µg) administration and every 15 minutes after administration, up to 60 minutes post administration. Follow-up of patient satisfaction with pain control and treatment was assessed 24 hours after discharge. The primary outcome was safety as evidenced by adverse events. Secondary outcomes included the above-mentioned vital signs and pain ratings. RESULTS: No adverse events occurred in the present study and all participants maintained an acceptable level of awareness throughout the assessment period. One-way repeated measures analyses of covariance tests with Bonferroni-adjusted means indicated that oxygen saturation, blood pressure, and heart rate changed from baseline, whereas pain scores were lower at post-administration levels compared with baseline. Finally, the majority of participants reported being satisfied with pain control and treatment. CONCLUSION: Preliminary evidence indicates that intranasal fentanyl is safe and effective for lumbar facet radiofrequency ablation procedures. Future rigorous randomized control trials are needed to confirm the present results and to examine the effects of intranasal fentanyl on intraoperative and postoperative opioid use.

Randomized, double-blind, comparative-effectiveness study comparing pulsed radiofrequency to steroid injections for occipital neuralgia or migraine with occipital nerve tenderness.

Occipital neuralgia (ON) is characterized by lancinating pain and tenderness overlying the occipital nerves. Both steroid injections and pulsed radiofrequency (PRF) are used to treat ON, but few clinical trials have evaluated efficacy, and no study has compared treatments. We performed a multicenter, randomized, double-blind, comparative-effectiveness study in 81 participants with ON or migraine with occipital nerve tenderness whose aim was to determine which treatment is superior. Forty-two participants were randomized to receive local anesthetic and saline, and three 120 second cycles of PRF per targeted nerve, and 39 were randomized to receive local anesthetic mixed with deposteroid and 3 rounds of sham PRF. Patients, treating physicians, and evaluators were blinded to interventions. The PRF group experienced a greater reduction in the primary outcome measure, average occipital pain at 6 weeks (mean change from baseline -2.743 ± 2.487 vs -1.377 ± 1.970; P < 0.001), than the steroid group, which persisted through the 6-month follow-up. Comparable benefits favoring PRF were obtained for worst occipital pain through 3 months (mean change from baseline -1.925 ± 3.204 vs -0.541 ± 2.644; P = 0.043), and average overall headache pain through 6 weeks (mean change from baseline -2.738 ± 2.753 vs -1.120 ± 2.1; P = 0.037). Adverse events were similar between groups, and few significant differences were noted for nonpain outcomes. We conclude that although PRF can provide greater pain relief for ON and migraine with occipital nerve tenderness than steroid injections, the superior analgesia may not be accompanied by comparable improvement on other outcome measures.

Epidural lysis of adhesions for failed back surgery and spinal stenosis: factors associated with treatment outcome.

BACKGROUND: Failed back surgery syndrome (FBSS) is a challenging problem. One treatment advocated to treat FBSS is epidural lysis of adhesions (LOA). The results of studies examining LOA for FBSS have been mixed, but are limited because no study has ever sought to identify factors associated with outcomes. METHODS: We performed this multicenter, retrospective study in 115 patients who underwent LOA for FBSS (n = 104) or spinal stenosis (n = 11) between 2004 and 2007. Twenty-seven demographic, clinical, and procedural variables were extracted from medical records and correlated with the outcome, defined as ≥50% pain relief lasting ≥1 month. Univariable analysis was performed, followed by multivariable logistic regression. RESULTS: Overall, 48.7% (95% confidence interval [CI], 39.3%-58.1%) of patients experienced a positive outcome. In univariable analysis, those who had a positive outcome were older (mean age 64.1 years; 95% CI, 59.7-68.6 vs 57.2; 95% CI, 53.0-61.4 years; P = 0.02), while higher baseline numerical rating scale pain scores were associated with a negative outcome (mean 6.7 years; 95% CI, 6.0-7.3 vs 7.5; 95% CI, 6.9-8.0; P = 0.07). Use of hyaluronidase did not correlate with outcomes in univariable analysis (odds ratio [OR], 1.2; 95% CI, 0.6-2.5; P = 0.65). In multivariable analysis, age ≥81 years (OR, 7.8; 95% CI, 1.4-53.7), baseline numerical rating scale score ≤9 (OR, 4.4; 95% CI, 1.4-16.3, P = 0.02), and patients on or seeking disability or worker's compensation (OR, 4.4; 95% CI, 1.1-19.5, P = 0.04) were significantly more likely to experience a positive outcome. CONCLUSIONS: Considering our modest success rate, selecting patients for epidural LOA based on demographic and clinical factors may help better select treatment candidates. Procedural factors such as the use of hyaluronidase that increase risks and costs did not improve outcomes, so further research is needed before these become standard practice.

The application of genomic and molecular data in the treatment of chronic cancer pain.

Many cancer patients will develop complex pain syndromes requiring aggressive, innovative, and comprehensive multimodal pain management strategies. Recently, data from both animal studies and clinical trials have allowed clinical research to focus on creating applicable clinical treatment strategies. This article is a review of genomic and molecular data, which has contributed to creating novel modalities for use in clinical pain management of patients with cancer-induced pain.

Headaches during war: analysis of presentation, treatment, and factors associated with outcome.

BACKGROUND: Headache is often associated with physical trauma and psychological stress. The aim of this study is to evaluate the impact of headache on personnel deployed in war zones and to identify factors associated with return to duty (RTD). METHODS: Outcome data were prospectively collected on 985 personnel medically evacuated out of Operations Iraqi and Enduring Freedom for a primary diagnosis of headache between 2004 and 2009. Electronic medical records were reviewed to examine clinical and treatment patterns and the effect that myriad factors had on RTD. RESULTS: 33.6% of evacuees returned to duty. The most common headaches were post-concussion (34.1%) and migraine (30.0%). Headaches typically associated with trauma such as post-concussion (18.7%), occipital neuralgia (23.1%), and cervicogenic headache (29.7%) had the lowest RTD rates, whereas tension headache (49.6%) was associated with the best outcome. Other variables associated with negative outcome included presence of aura (OR 0.51, 95% CI 0.30-0.88; p = 0.02), traumatic brain injury (OR 0.50, 95% CI 0.29-0.87; p = 0.01), opioid (OR 0.41, 95% CI 0.26-0.63; p < 0.001), and beta-blocker (OR 0.26, 95% CI 0.12-0.61; p = 0.002) use, and co-existing psychopathology (p < 0.001 in univariable analysis). CONCLUSION: Headaches represent a significant cause of unit attrition in personnel deployed in military operations, with physical trauma and co-existing psychopathology associated with poorer outcomes.

Does difficult mask ventilation predict obstructive sleep apnea? A prospective pilot study to identify the prevalence of osa in patients with difficult mask ventilation under general anesthesia.

BACKGROUND: Given the pathogenesis of obstructive sleep apnea (OSA), anesthesiologists may be in a unique position to rapidly identify patients who are at risk for undiagnosed OSA in the perioperative period. Identification is the first step in prompt diagnosis and potential prevention of OSA related comorbidities. Patients who exhibit unanticipated difficult mask ventilation (DMV) during induction of general anesthesia may be at risk of having undiagnosed OSA. OBJECTIVE: To determine the association of OSA in patients with difficult mask ventilation under general anesthesia. METHODS: Ten patients were identified over a 2-year period at the time of anesthetic induction as being difficult to mask ventilate and were then enrolled in this prospective pilot study. After enrollment and informed consent, the patients were referred to the sleep study center for full overnight polysomnography to evaluate for the presence and severity of OSA. RESULTS: Of our cohort, 9/10 patients exhibited polysomnographic evidence of OSA, while the last subject tested positive for sleep disordered breathing. Eighty percent (8/10) of subjects espoused snoring, but only 10% (1/10) reported witnessed apneas. Average DMV was 2.5, and higher grades of DMV were associated with more severe OSA. CONCLUSION: In this study, difficult mask ventilation was predictive of undiagnosed OSA. Anesthesiologists may be in a unique position to identify patients at risk for OSA and prevention of related comorbidities.

Continuous thoracic paravertebral nerve block in a working anesthesia resident-when opioids are not an option.

Multiple unilateral rib fractures can cause significant pain and morbidity. Continuous nerve block catheters are often maintained while inpatient, and patients are discharged with oral analgesics. However, in many institutions, this dynamic is changing and patients are being managed effectively with outpatient catheters. A 45-year-old male was presented with fractured right ribs 6 through 9. The patient was an anesthesiology resident and was unable to perform his clinical duties. Single paravertebral nerve blocks were performed at right thoracic levels 6-9. At the T7 level, an indwelling catheter was placed. On post-injury day 18, he was able to discontinue the catheter and there were no associated complications. We report a unique case of a patient with multiple rib fractures who was not able to be exposed to potential side effects of opioids. The use of a continuous thoracic paravertebral nerve in an outpatient setting allowed a faster return to function with no adverse events.

Development of a complicated pain syndrome following cyanide poisoning in a U.S. soldier.

A majority of modern war wounds are caused by blasts and high-energy ballistics. Extremity injuries predominate since modern body armor does not protect these areas due to mobility limitations. A less known and more insidious mechanism of enemy attack among our soldiers involves treachery by the local populace posing as noncombatants. One such recent event involved the contamination of tobacco with cyanide (CN). We describe a case of a soldier with CN intoxication due to ingestion of tobacco purchased from a local merchant. The soldier developed a complex neuropathic pain syndrome and was successfully treated with an inpatient high-dose intravenous ketamine infusion in combination with continuous peripheral nerve blockade.

Ultrasound-guided cryoablation of genitofemoral nerve for chronic inguinal pain.

BACKGROUND: Cryotechnology is a modality of renewed interest in pain management. It is safe and effective when used to treat neuropathies of sensory and mixed nerves. Cryoablation, in general, is devoid of the risk of neuroma formation and can provide several weeks to months of adequate pain relief. Traditionally, cryoablation was applied blindly to the target area. The use of ultrasound guidance may improve the efficacy and reduce morbidity. We report a case of a successful cryoablation of the femoral component of the genitofemoral nerve using ultrasound guidance in a patient with chronic inguinal pain. A 47 year-old male (ASA Classification II for obesity, HLD, and OSA, 125kg, 69 in) presented to the Walter Reed Pain Clinic with the complaint of 4/10 VAS left sided groin pain of 3 month duration. The patient was diagnosed with a neuropathy of the femoral component of the left genitofemoral nerve. He received a diagnostic block with local anesthetic and reported immediate pain relief that lasted one week. The patient was counseled on the risks and benefits of cryoablation. The skin was anesthetized with 1% lidocaine and a 14 gauge angiocatheter needle was introduced using an in-plane technique to the target area. A Westco Cryoablation machine (San Diego, California) with a 14 gauge Lloyd Neurostat cryoprobe was then passed via the angiocatheter. The area was treated for two 3-minute intervals while the cryo probe was visualized under ultrasound. Ultrasound is increasingly utilized for both acute and chronic pain procedures. Ultrasound offered several advantages in this case. It allowed a smaller gauge introducer and cryoablation probe to be used since there was better visualization of the target area. Ultrasound helped identify important vascular structures, allowing safe introduction of the introducer and cryoablation probe. The patient remains pain free at 2-month follow-up.

Loss of resistance technique for paravertebral nerve blockade using the Episure Autodetect Syringe--a case report.

INTRODUCTION: Postoperative pain is a frequent occurrence following breast surgery. Some authors have reported the incidence of postoperative pain following mastectomy and breast reconstruction to be as high as 50% when general anesthesia and intravenous narcotics are the primary anesthetic. An alternative anesthetic technique for breast surgery and postoperative analgesia is paravertebral nerve blockade (PVB). Greengrass and Weltz have described improved patient satisfaction, less analgesic requirement, and less total anesthetic use in those patients with preoperative PVBs. One of the challenges in providing successful analgesia from PVBs is the ability to correctly identify the paravertebral space. Landmark-based anatomy with penetration of the superior costotransverse ligament 1 cm past the transverse process has been previously described. Boezaart has described the use of loss of resistance (LOR) when performing PVBs. One potential difficulty with this technique is the reliance on the subjective feel of resistance loss as the needle passes into the paravertebral space. CASE REPORT: The Episure Autodetect Syringe is currently indicated by the US Food and Drug Administration for use with an epidural needle for the verification for needle tip placement in the epidural space. The principle, however, of LOR is similar when performing PVBs. We report a case of the successful use of the Episure Autodetect Syringe (ADS) for confirming entry into the paravertebral space. CONCLUSION: To our knowledge, this is the first described use of the ADS for performing PVB.

Awake thyroidectomy under local anesthesia and dexmedetomidine infusion.

UNLABELLED: Dexmedetomidine (DEX) is an alpha-2 receptor agonist with sedative and analgesic properties. It has been reported to preserve the patient's ability to cooperate and provide opioid sparing properties. Patients with obstructive sleep apnea (OSA) have demonstrated an increased risk for oxygen desaturation following general anesthesia. We report a case of a 64-year-old male, ASA IV with severe chronic obstructive pulmonary disease, OSA, unilateral vocal cord dysfunction, gastro-esophageal reflux disease, and congestive heart failure undergoing an awake thyroidectomy under local anesthesia and a DEX infusion. The patient was given a loading dose of DEX of 1 mcg/kg and an infusion ranging from 0.2 to 1.0 g/kg/hr. He received a total of 250 mcg of fentanyl and 7.5 mg of ketorolac throughout the case. RESULTS: The patient tolerated the procedure well. He was able to cooperate with simple commands. His vital signs remained stable. He reported a pain score of 2 out of 10 in the recovery unit. CONCLUSIONS: This case demonstrates the successful use of a DEX infusion along with local anesthesia administered by the surgeon for an awake thyroidectomy.

Safety of multiple, simultaneous continuous peripheral nerve block catheters in a patient receiving therapeutic low-molecular-weight heparin.

OBJECTIVE: The application of continuous peripheral nerve block (CPNB) has been an important anesthetic tool in the management of combat soldiers wounded from current conflicts. Placing and maintaining CPNBs becomes a challenge in this patient population due to concomitant prophylactic and therapeutic anticoagulation. CASE REPORT: A 32-year-old male sustained multiple traumatic injuries from an improvised explosive device, including a right tibial fracture, a left tibial fracture, and a left ulnar fracture. His pain was originally well controlled with a left infraclavicular CPNB (0.2% ropivacaine at 10 mL/h with 3 mL bolus every 20 minutes) and an epidural (0.2% ropivacaine at 10 mL/h with 5 mL bolus every 30 minutes). He subsequently developed a common femoral vein thrombus and was treated with low-molecular-weight heparin. His epidural catheter was discontinued; however, his pain was not well controlled with intravenous and oral pain medication. We elected to place bilateral, tunneled sciatic CPNBs and a left, tunneled femoral CPNB. We started infusions of 0.2% ropivacaine at 10 mL/h in each catheter, in addition to 5 mL every 30 minutes demand dose in each sciatic catheter. The patient's serum ropivacaine levels were analyzed 24 hours after the start of the infusions and were found to be 5.8 mg/L and <0.1 mg/L for total and free concentrations, respectively. CONCLUSIONS: This case highlights the application of simultaneous CPNB techniques in a patient with multiple extremity injuries receiving anticoagulant therapy.