Andres Missair

A 3-dimensional ultrasound study of local anesthetic spread during lateral popliteal nerve block: What is the ideal end point for needle tip position?

Background and Objectives Recent clinical trials suggest that subfascial (sometimes termed subepineural) injections result in faster block onset and success compared with conventional techniques. This prospective, randomized, observer-blinded study measured and compared the 3-dimensional spread pattern and volume of perineural local anesthetic (LA) in contact with the sciatic nerve after subfascial versus extrafascial lateral popliteal injections. Methods Sixty patients were randomly assigned to either the subfascial or the extrafascial injection group. All patients received a single-injection, US-guided lateral popliteal sciatic nerve block for postoperative pain. Depending on group assignment, the needle tip was placed outside or beneath the sciatic fascial sheath for a single injection of 30 mL of ropivacaine 0.5%. Using 3-dimensional ultrasound imaging, postblock scans were acquired to quantify the volume and spread pattern of perineural LA around the sciatic nerve in each group. Results The mean LA perineural volume for the extrafascial group was 1.48 (SD, 0.50) mL versus a mean of 5.57 (SD, 1.68) mL for the subfascial group, P < 0.05. The mean distance of longitudinal perineural LA spread (along the length of the nerve) for the subfascial group was 66% greater than that observed using the conventional technique (9.3 vs 5.6 cm, P < 0.01). Complete sensory block to pinprick for the extrafascial group was 63% versus 90% (P < 0.05) for the subfascial group. Conclusions Placement of the needle tip beneath the complex fascial sheath of the sciatic nerve resulted in significantly greater perineural local anesthetic volume following a single-injection lateral popliteal approach at the nerve bifurcation and was associated with greater sensory blockade and a characteristic laminar LA spread pattern.

Surgery under extreme conditions in the aftermath of the 2010 haiti earthquake: The importance of regional anesthesia

The 12 January 2010 earthquake that struck Port-au-Prince, Haiti caused >200,000 deaths, thousands of injuries requiring immediate surgical interventions, and 1.5 million internally displaced survivors. The earthquake destroyed or disabled most medical facilities in the city, seriously hampering the ability to deliver immediate life- and limb-saving surgical care. A Project Medishare/University of Miami Miller School of Medicine trauma team deployed to Haiti from Miami within 24 hours of the earthquake. The team began work at a pre-existing tent facility in the United Nations (UN) compound based at the airport, where they encountered 225 critically injured patients. However, non-sterile conditions, no means to administer oxygen, the lack of surgical equipment and supplies, and no anesthetics precluded the immediate delivery of general anesthesia. Despite these limitations, resuscitative care was administered, and during the first 72 hours following the event, some amputations were performed with local anesthesia. Because of these austere conditions, an anesthesiologist, experienced and equipped to administer regional block anesthesia, was dispatched three days later to perform anesthesia for limb amputations, debridements, and wound care using single shot block anesthesia until a better equipped tent facility was established. After four weeks, the relief effort evolved into a 250-bed, multi-specialty trauma/intensive care center staffed with >200 medical, nursing, and administrative staff. Within that timeframe, the facility and its staff completed 1,000 surgeries, including spine and pediatric neurological procedures, without major complications. This experience suggests that when local emergency medical resources are completely destroyed or seriously disabled, a surgical team staffed and equipped to provide regional nerve block anesthesia and acute pain management can be dispatched rapidly to serve as a bridge to more advanced field surgical and intensive care, which takes longer to deploy and set up.

A matter of life or limb? A review of traumatic injury patterns and anesthesia techniques for disaster relief after major earthquakes

BACKGROUND:All modalities of anesthetic care, including conscious sedation, general, and regional anesthesia, have been used to manage earthquake survivors who require urgent surgical intervention during the acute phase of medical relief. Consequently, we felt that a review of epidemiologic data from major earthquakes in the context of urgent intraoperative management was warranted to optimize anesthesia disaster preparedness for future medical relief operations. The primary outcome measure of this study was to identify the predominant preoperative injury pattern (anatomic location and pathology) of survivors presenting for surgical care immediately after major earthquakes during the acute phase of medical relief (0–15 days after disaster). The injury pattern is of significant relevance because it closely relates to the anesthetic techniques available for patient management. We discuss our findings in the context of evidence-based strategies for anesthetic management during the acute phase of medical relief after major earthquakes and the associated obstacles of devastated medical infrastructure. METHODS:To identify reports on acute medical care in the aftermath of natural disasters, a query was conducted using MEDLINE/PubMed, Embase, CINAHL, as well as an online search engine (Google Scholar). The search terms were “disaster” and “earthquake” in combination with “injury,” “trauma,” “surgery,” “anesthesia,” and “wounds.” Our investigation focused only on studies of acute traumatic injury that specified surgical intervention among survivors in the acute phase of medical relief. RESULTS:A total of 31 articles reporting on 15 major earthquakes (between 1980 and 2010) and the treatment of more than 33,410 patients met our specific inclusion criteria. The mean incidence of traumatic limb injury per major earthquake was 68.0%. The global incidence of traumatic limb injury was 54.3% (18,144/33,410 patients). The pooled estimate of the proportion of limb injuries was calculated to be 67.95%, with a 95% confidence interval of 62.32% to 73.58%. CONCLUSIONS:Based on this analysis, early disaster surgical intervention will focus on surviving patients with limb injury. All anesthetic techniques have been safely used for medical relief. While regional anesthesia may be an intuitive choice based on these findings, in the context of collapsed medical infrastructure, provider experience may dictate the available anesthetic techniques for earthquake survivors requiring urgent surgery.

Development and Validation of an Assessment of Regional Anesthesia Ultrasound Interpretation Skills.

Background Interpretation of ultrasound images and knowledge of anatomy are essential skills for ultrasound-guided peripheral nerve blocks. Competency-based educational models promoted by the Accreditation Council for Graduate Medical Education require the development of assessment tools for the achievement of different competency milestones to demonstrate the longitudinal development of skills that occur during training. Methods A rigorous study guided by psychometric principles was undertaken to identify and validate the domains and items in an assessment of ultrasound interpretation skills for regional anesthesia. A survey of residents, academic faculty, and community anesthesiologists, as well as video recordings of experts teaching ultrasound-guided peripheral nerve blocks, was used to develop short video clips with accompanying multiple choice–style questions. Four rounds of pilot testing produced a 50-question assessment that was subsequently administered online to residents, fellows, and faculty from multiple institutions. Results Test results from 90 participants were analyzed with Item Response Theory model fitting indicating that a 47-item subset of the test fits the model well (P = 0.11). There was a significant linear relation between expected and predicted item difficulty (P < 0.001). Overall test scores increased linearly with higher levels of formal anesthesia training, regional anesthesia training, number of ultrasound-guided blocks performed per year, and a self-rating of regional anesthesia skill (all P < 0.001). Conclusions This study provides evidence for the reliability, content validity, and construct validity of a 47-item multiple choice–style online test of ultrasound interpretation skills for regional anesthesia, which can be used as an assessment of competency milestone achievement in anesthesiology training.

Anesthetic Implications of Ebola Patient Management: A Review of the Literature and Policies.

As of mid-October 2014, the ongoing Ebola epidemic in Western Africa has affected approximately 10,000 patients, approached a 50% mortality rate, and crossed political and geographic borders without precedent. The disease has spread throughout Liberia, Guinea, and Sierra Leone. Isolated cases have arrived in urban centers in Europe and North America. The exponential growth, currently unabated, highlights the urgent need for effective and immediate management protocols for the various health care subspecialties that may care for Ebola virus disease patients. We conducted a comprehensive review of the literature to identify key areas of anesthetic care affected by this disease. The serious potential for “high-risk exposure” and “direct contact” (as defined by the Centers for Disease Control and Prevention) of anesthesiologists caring for Ebola patients prompted this urgent investigation. A search was conducted using MEDLINE/PubMed, MeSH, Cochrane Review, and Google Scholar. Key words included “anesthesia” and/or “ebola” combined with “surgery,” “intubation,” “laryngoscopy,” “bronchoscopy,” “stethoscope,” “ventilation,” “ventilator,” “phlebotomy,” “venous cannulation,” “operating room,” “personal protection,” “equipment,” “aerosol,” “respiratory failure,” or “needle stick.” No language or date limits were applied. We also included secondary-source data from government organizations and scientific societies such as the Centers for Disease Control and Prevention, World Health Organization, American Society of Anesthesiologists, and American College of Surgeons. Articles were reviewed for primary-source data related to inpatient management of Ebola cases as well as evidence-based management guidelines and protocols for the care of Ebola patients in the operative room, infection control, and health care worker personal protection. Two hundred thirty-six articles were identified using the aforementioned terminology in the scientific database search engines. Twenty articles met search criteria for information related to inpatient Ebola virus disease management or animal virology studies as primary or secondary sources. In addition, 9 articles met search criteria as tertiary sources, representing published guidelines. The recommendations developed in this article are based on these 29 source documents. Anesthesia-specific literature regarding the care of Ebola patients is very limited. Secondary-source guidelines and policies represent the majority of available information. Data from controlled animal experiments and tuberculosis patient research provide some evidence for the existing recommendations and identify future guideline considerations.

Accuracy and consistency of modern elastomeric pumps.

Abstract Continuous peripheral nerve blockade has become a popular method of achieving postoperative analgesia for many surgical procedures. The safety and reliability of infusion pumps are dependent on their flow rate accuracy and consistency. Knowledge of pump rate profiles can help physicians determine which infusion pump is best suited for their clinical applications and specific patient population. Several studies have investigated the accuracy of portable infusion pumps. Using methodology similar to that used by Ilfeld et al, we investigated the accuracy and consistency of several current elastomeric pumps.

Comparison of outside versus inside brachial plexus sheath injection for ultrasound-guided interscalene nerve blocks

Ultrasound‐guided interscalene brachial plexus blocks are commonly used to provide anesthesia for the shoulder and proximal upper extremity. Some reviews identify a sheath that envelops the brachial plexus as a potential tissue plane target, and current editorials in the literature highlight the need to establish precise and reproducible injection targets under ultrasound guidance. We hypothesize that an injection of a local anesthetic inside the brachial plexus sheath during ultrasound‐guided interscalene nerve blocks will result in enhanced procedure success and provide a consistent tissue plane target for this approach with a reproducible and characteristic local anesthetic spread pattern.

Motor-Sparing Surgical Nerve Blocks for Upper Extremity Surgery:Significantly Less Motor Paralysis Using 15 mL versus 30 mL ofMepivacaine 1.5% for Supraclavicular Block - A Prospective RandomizedDouble-Blinded Study

Background and objectives: We performed a prospective randomized double-blinded study evaluating if a reduced volume of local anesthetic would result in operative limb surgical anesthesia while decreasing motor paralysis during an ultrasound-guided supraclavicular nerve block. Current tendencies in clinical practice towards smaller injectate volumes during ultrasound-guided nerve block placement prompted our investigation on its impact regarding block quality. Methods: 43 patients were consented for this prospective, double-blinded randomized clinical trial. Each patient was randomly assigned. Group HIGH received the conventional injection dose of 30 mL of 1.5% Mepivacaine. Group LOW received the reduced volume dose of 15 mL. An ultrasound-guided supraclavicular nerve block was performed on each patient. Motor block and sensory perception to pin-prick were assessed in the nerve distributions for the ulnar, median, radial, and musculocutaneous branches at 5, 10, 15, 20, and 30 minutes post-injection. Results: Complete motor block in the radial, ulnar, musculocutaneous and median nerve distributions at 30 minutes, was present in 55% of patients in Group HIGH versus 10% in Group LOW and was statistically significant between both groups (p<0.01). The anatomic distribution of the observed motor-sparing was statistically significant in the median (p<0.01) and ulnar (p<0.05) nerve branches among those patients who received 15 mL LA boluses. Conclusions: Our study demonstrated that 15 mL vs. 30 mL injections of mepivacaine 1.5% at the supraclavicular approach provide equivalent surgical anesthesia, while reducing the incidence of motor block. These findings may have implications on early postoperative physical therapy for the subset of patients that present with Galeazzi-type fractures, carpal tunnel syndrome, and minimally-displaced distal radius fractures.

Postoperative pain management

Postoperative pain remains a significant problem for patients undergoing ambulatory and in-house surgery and is frequently undermanaged. Ineffective pain control can result in negative outcomes such as prolonged rehabilitation, delayed wound healing, cardiovascular complications, and development of chronic pain. Consequently, physicians involved in postoperative pain management should develop individualized strategies based on patient characteristics and surgical procedures. Ideally, a specific plan for postoperative pain management is developed prior to surgery and includes the patient and physician and caregivers from several medical disciplines. A multimodal approach utilizes agents from different drug classes and various techniques and allows targeting different receptors and pain pathways. In addition, such an approach avoids side effects frequently associated with monotherapy. Over the last decade, regional anesthesia techniques and especially peripheral nerve blocks have emerged as an important component of such a multimodal approach. The ability of peripheral nerve blocks to provide effective and tailored pain control in combination with a favorable side-effect profile has resulted in outcome improvements, especially after major orthopedic surgery. This chapter will review the different tools available to the pain management physician and his team and illustrate their individual strengths and indications.