Preventing and Treating Hypoxia: Using a Physiology Simulator to Demonstrate the Value of Pre-Oxygenation and the Futility of Hyperventilation.

INTRODUCTION: Insufficient pre-oxygenation before emergency intubation, and hyperventilation after intubation are mistakes that are frequently observed in and outside the operating room, in clinical practice and in simulation exercises. Physiological parameters, as appearing on standard patient monitors, do not alert to the deleterious effects of low oxygen saturation on coronary perfusion, or that of low carbon dioxide concentrations on cerebral perfusion. We suggest the use of HumMod, a computer-based human physiology simulator, to demonstrate beneficial physiological responses to pre-oxygenation and the futility of excessive minute ventilation after intubation. METHODS: We programmed HumMod, to A.) compare varying times (0-7 minutes) of pre-oxygenation on oxygen saturation (SpO2) during subsequent apnoea; B.) simulate hyperventilation after apnoea. We compared the effect of different minute ventilation rates on SpO2, acid-base status, cerebral perfusion and other haemodynamic parameters. RESULTS: A.) With no pre-oxygenation, starting SpO2 dropped from 98% to 90% in 52 seconds with apnoea. At the other extreme, following full pre-oxygenation with 100% O2 for 3 minutes or more, the SpO2 remained 100% for 7.75 minutes during apnoea, and dropped to 90% after another 75 seconds. B.) Hyperventilation, did not result in more rapid normalization of SpO2, irrespective of the level of minute ventilation. However, hyperventilation did cause significant decreases in cerebral blood flow (CBF). CONCLUSIONS: HumMod accurately simulates the physiological responses compared to published human studies of pre-oxygenation and varying post intubation minute ventilations, and it can be used over wider ranges of parameters than available in human studies and therefore available in the literature.

The use of simulation in healthcare: from systems issues, to team building, to task training, to education and high stakes examinations.

PURPOSE OF REVIEW: Simulation in healthcare is becoming increasingly used. This review will spotlight some of the uses of simulation in healthcare training. RECENT FINDINGS: Previously, evaluation of simulation training was typically from evaluations from trainees. Recent articles, however, have linked simulation training to actual patient outcomes and demonstrated skill retention up to 1 year. Objective measurements have demonstrated positive effects on healthcare education, have been successfully used in high stakes examinations, and have uncovered systems and patient safety issues. SUMMARY: This article will review some recent studies showing how simulation can have a positive effect on patient outcomes and skill retention, uncover systems issues related to patient safety, and how simulation can be used in credentialing, and other high stakes examinations.

Nerve stimulator-assisted sciatic nerve block for painful procedures in the ED.

OBJECTIVE: Emergency physicians must frequently perform painful procedures on an urgent basis. These are most commonly performed using procedural sedation techniques involving parenteral sedatives and/or analgesics. Popliteal block of the sciatic nerve is a proven and safe technique used extensively in anesthesiology practice for distal lower extremity analgesia. This technique offers the advantage of relative cardiopulmonary safety, dense and prolonged analgesia, and maintenance of normal airway reflexes in patients with increased aspiration risks. The objective of this study was to explore the usefulness of sciatic nerve block in the popliteal fossa in the emergency department (ED) setting. METHODS: We performed a retrospective analysis of all ED popliteal nerve block cases at our institution from April 2009 to April 2010. Sixteen cases were found where popliteal block was used for pain management during procedures of the leg, ankle, and foot, including fracture reduction, splinting, irrigation, and debridement. Procedural success was defined as successful completion of the technique without the need for additional procedural sedatives, patient satisfaction, and adequate postprocedural analgesia. RESULTS: A high degree of satisfaction was seen in our patient population, and all procedures were successfully completed. Tibial nerve rather than common peroneal nerve stimulation correlated with success of the block. Postprocedural analgesia was excellent in all cases and predictably lasted 90 to 120 minutes. CONCLUSIONS: Although limited by small numbers and its retrospective nature, this review of popliteal nerve block for painful lower extremity procedures in the ED suggests that this technique may be an attractive alternative in selected cases to parenteral procedural sedation.

Tracheoinnominate Artery Fistula.

Audience: This simulation provides training for emergency medicine residents in the stepwise management of a patient who presents with bleeding from a tracheoinnominate artery fistula. Additional learners who might benefit from this simulation are otolaryngology and general surgery residents as well as critical care fellows. Introduction: Hemorrhage from a tracheoinnominate artery fistula (TIAF) is a rare but life-threatening complication in a patient with a recent tracheostomy. This complication occurs in 0.7% of tracheostomy patients with a mortality of 50-70%.1 Seventy-five percent of patients with a TIAF will present within the first three weeks of surgery and 50% of patients will present with a sentinel bleed that briefly resolves.1 Key elements of a history and exam that should raise a provider's concern for this diagnosis include a recent tracheostomy (within the last 4 weeks), a percutaneous tracheostomy, prior radiation, chronic steroid use, a neck or chest deformity or a sentinel bleed.2 Survival from a TIAF hinges upon emergent, operative repair by an otolaryngologist and cardiothoracic surgeon. Cuff hyperinflation and the Utley Maneuver are critical bedside interventions to temporize this massive bleed and stabilize the patient for definitive, operative repair. Educational Objectives: By the end of this simulation, learners will be able to: 1) perform a focused history and physical exam on any patient who presents with bleeding from the tracheostomy site, 2) describe the differential diagnosis of bleeding from a tracheostomy site, including a TIAF, 3) demonstrate the stepwise management of bleeding from a suspected TIAF, including cuff hyperinflation and the Utley Maneuver, 4) verify that definitive airway control via endotracheal intubation is only feasible in the tracheostomy patient when it is clear, upon history and exam, that the patient can be intubated from above, 5) demonstrate additional critical actions in the management of a patient with a TIAF, including early consultation with otolaryngology and cardiothoracic surgery as well as emergent blood transfusion and activation of a massive transfusion protocol. Educational Methods: This case was written with a modified, low-fidelity manikin, traditionally used for training in nasogastric tube placement and tracheostomy care. We modified this manikin to simulate a hemorrhage from the tracheostomy site.3 The patient in our case had a history of laryngeal cancer, and thus we occluded his larynx for this simulation. As a result of this obstruction, he was unable to be intubated from above. We provided confederates, a bedside nurse and family member, to assist the learners throughout the case. We also utilized a simulation technician to operate dynamic vital signs on a simulated cardiac monitor. It would be technically challenging to adapt this case to a high-fidelity simulator due to potential for damage of the internal electrical elements by the large amount of artificial blood from the tracheostomy tube. However, a mechanical pump provided a useful means of active bleeding in this low-fidelity manikin. Research Methods: We provided a pre- and post-simulation questionnaire for the 33 emergency medicine residents who participated in this simulation. There were 11 residents from each of the PGY-1, PGY-2 and PGY-3 year-groups. Thirty-two residents (97%) completed the pre-survey and 33 residents (100%) completed the post-survey. For our questions, we used a 5-point Likert Scale to assess a resident's knowledge of the learning objectives within this simulation. Results: Responses from our pre- and post- survey indicated a significant improvement in knowledge about a tracheoinnominate artery fistula as well as the general management of tracheostomy complications in the emergency department. Discussion: This simulation is a useful educational tool for instructing emergency medicine residents on optimal management of tracheostomy emergencies such as a TIAF. The interprofessional teaching by an emergency medicine attending and mid-level (PGY-3) otolaryngology resident allowed for a richer and more detailed discussion during the debriefing. Throughout the case, the emergency medicine attending played the role of a bedside nurse and offered supportive, clinical cues when bleeding recurred. The otolaryngology resident played the role of a family member and offered helpful cues during the history and exam portion of the case. Following the case, both content experts provided useful clinical insight during the debriefing. If staffing availability permits, it might be advantageous to use additional simulation-trained personnel to play the roles of the nurse and family member, thus allowing the emergency medicine attending and otolaryngology content experts to simply view the case from the control room and perform the debriefing. Topics: Tracheostomy, surgical airway, tracheoinnominate artery fistula, bleeding from tracheostomy site, complications with tracheostomies, hemorrhagic shock.

Modified Manikin for Tracheoinnominate Artery Fistula.

Audience: This simulator is designed to instruct emergency medicine residents in tracheostomy training that involves bleeding from the tracheostomy site. Any resident, fellow, or attending physician who cares for patients with complications from their tracheostomy might benefit from this innovation. Introduction: The emergency medicine provider must maintain proficiency in caring for patients with complications from their tracheostomy. In the United States, over 110,000 patients receive tracheostomies per year.1 A rare but catastrophic complication of tracheostomies, usually within the first month of placement, is a tracheoinnominate artery fistula (TIAF). This complication occurs in 0.7% of tracheostomy patients and carries a 50-70% mortality.1,2 We modified a low-fidelity tracheostomy manikin to instruct learners in the stepwise management of hemorrhage from a TIAF. Educational Objectives: By the end of this educational session, learners will be able to:Perform a focused history and physical exam on any patient who presents with bleeding from the tracheostomy site.Describe the differential diagnosis of bleeding from a tracheostomy site, including a TIAF.Demonstrate the stepwise management of bleeding from a suspected TIAF, including cuff hyperinflation and the Utley Maneuver.Verify that definitive airway control via endotracheal intubation is only feasible in the tracheostomy patient when it is clear, upon history and exam, that the patient can be intubated from above.Demonstrate additional critical actions in the management of a patient with a TIAF, including early consultation with otolaryngology and cardiothoracic surgery as well as emergent blood transfusion and activation of a massive transfusion protocol. Educational Methods: This modified manikin is a useful training tool for any healthcare provider who is involved in the treatment and stabilization of a variety of tracheostomy emergencies, from bleeding to infection to obstruction or dislodgement. Our case was presented on two separate occasions, to otolaryngology interns (PGY-1), and emergency medicine residents (PGY 1-3). It involved the care of a patient with a sentinel bleed and subsequent hemorrhage from a tracheoinnominate artery fistula (TIAF). This low-fidelity tracheostomy manikin provides the ideal platform for any complex, tracheostomy case, particularly where ongoing bleeding from the tracheostomy site might permanently damage the electrical circuitry of a high-fidelity model. We initially fashioned this modified manikin for tracheostomy training during a simulation "boot camp" for otolaryngology PGY-1 residents. Our use of this modified manikin for tracheostomy training was a useful teaching tool during our otolaryngology intern "boot camp." As a result, we organized a subsequent simulation training session with our PGY 1-3 emergency medicine residents to provide similar instruction in management of a TIAF. Research Methods: We provided a pre- and a post-simulation survey for the 33 emergency medicine residents who participated in the TIAF simulation with our modified tracheostomy manikin. There were 11 residents from each of the PGY-1, PGY-2, and PGY-3 year-groups. Thirty-two residents (97%) completed the pre-simulation survey, and 33 residents (100%) completed the post-simulation survey. We used a 6-point Likert Scale from "strongly agree" to "strongly disagree" to assess a resident's knowledge of multiple learning objectives within this simulation. Results: The pre- and post-simulation survey supported this simulation and manikin innovation as a useful teaching tool for tracheostomy emergencies such as a TIAF. Discussion: This was a useful innovation for emergency provider training in the recognition and management of a TIAF, a rare but emergent tracheostomy complication. In addition to this bleeding complication, this innovation might be useful for a variety of tracheostomy emergencies such as site infection, obstruction, and tube dislodgement. We highly recommend the involvement of both an emergency medicine and otolaryngology content expert in the design and debriefing of tracheostomy cases with this modified manikin. In our experience, a facilitated debriefing by an experienced clinician and educator from both fields provided a diverse perspective for challenging cases such as bleeding from a TIAF. Topics: Difficult airway, tracheostomy, tracheoinnominate fistula, hemorrhagic shock, tracheostomy complications, Utley Maneuver.

Persisting Hypocalcemia After Surgical Parathyroidectomy: The Differential Effectiveness of Calcium Citrate Versus Calcium Carbonate With Acid Suppression.

The effectiveness of oral calcium (Ca) may be contingent on a patient׳s factors beyond compliance, such as proton-pump inhibitor use and the choice of calcium supplements. A 32-year-old Hispanic male with end-stage renal disease on peritoneal dialysis underwent successful surgical parathyroidectomy (intact parathyroid hormone level: 2,328pg/mL; postsurgical: 287-69pg/mL [normal: 8.5-72.5]). His postoperative course was complicated by severe and recurrent hypocalcemia as outpatient and he needed repeated admissions for intravenous Ca gluconate. Initially, severe hypocalcemia (corrected Ca: 4.8-5.6mg/dL; nadir ionized Ca: 0.57-0.69mmol/L) was attributed solely to medical noncompliance with oral Ca carbonate (3750mg, 3×/day between meals) and calcitriol (2-4mcg/day). Recognizing coexisting treatment with proton-pump inhibitor, oral Ca supplement was changed to calcium citrate (2,850mg, 3×/day) with prompt resolution of hypocalcemia (corrected Ca: 8.1-8.3mg/dL). This current case and the included literature review emphasize the disproportionate effectiveness of Ca citrate in subjects with achlorhydria.

Relief of acute pain in chronic idiopathic gastroparesis with intravenous phentolamine.

OBJECTIVE: To report a case in which complete relief of pain associated with gastroparesis, with promotion of gastric emptying, was achieved with administration of phentolamine. CASE SUMMARY: A 37-year-old opiate-tolerant female with a history of recurrent abdominal pain, gastroparesis, cyclic vomiting syndrome, and migraine headaches was admitted to the emergency department (ED) with severe acute abdominal pain, nausea, and vomiting. The patient had been previously implanted with a permanent gastric electrical stimulator and she was adherent to her prokinetic, antiemetic, analgesic, and migraine prophylactic medications. Pain relief was achieved rapidly and completely in the ED with sympatholysis by administration of intravenous phentolamine 0.5 mg/kg over 60 minutes, with continuous cardiac monitoring. At a 2 month follow-up visit, the patient reported chronic pain relief, and a decrease in opiate doses was maintained by oral administration of clonidine 0.1 mg twice daily. DISCUSSION: Gastroparesis represents a difficult treatment challenge because management of gastric dysmotility and the accompanying severe abdominal pain is often mutually exacerbating and ineffective. Sympatholysis by intravenous phentolamine provided profound and immediate relief of acute gastroparesis-related abdominal pain in our patient. The mechanism of phentolamine is believed to be receptor blockade at alpha-adrenergic receptors and, therefore, inhibition of the peripheral sensitizing effects of circulating norepinephrine. Although action at a peripheral nerve level is presumed, modulation of alpha-adrenoreceptors receptors is also possible at the dorsal root ganglion or at other central nervous system sites. CONCLUSIONS: The dramatic relief of acute pain in gastroparesis by phentolamine observed in this case would warrant investigation of a larger, controlled case series. Patients who respond to intravenous sympatholysis may likewise be candidates for longer term sympathetic modulation with oral sympatholytics.

Acute oxalate nephropathy associated with orlistat.

BACKGROUND: Obesity is a major world-wide epidemic which has led to a surge of various weight loss-inducing medical or surgical treatments. Orlistat is a gastrointestinal lipase inhibitor used as an adjunct treatment of obesity and type 2 diabetes mellitus to induce clinically significant weight loss via fat malabsorption. CASE PRESENTATION: We describe a case of a 76-year-old female with past medical history of chronic kidney disease (baseline serum creatinine was 1.5-2.5 mg/dL), hypertension, gout and psoriatic arthritis, who was admitted for evaluation of elevated creatinine, peaking at 5.40 mg/dL. She was started on orlistat 120 mg three times a day six weeks earlier. Initial serologic work-up remained unremarkable. Percutaneous kidney biopsy revealed massive calcium oxalate crystal depositions with acute tubular necrosis and interstitial inflammation. Serum oxalate level returned elevated at 45 mm/l (normal <27). Timed 24-hour urine collection documented increased oxalate excretion repeatedly (54-96 mg/24 hour). After five renal dialysis sessions in eighth days she gradually regained her former baseline kidney function with creatinine around 2 mg/dL. Given coexisting proton-pump inhibitor therapy, only per os calcium-citrate provided effective intestinal oxalate chelation to control hyperoxaluria. CONCLUSIONS: Our case underscores the potential of medically induced fat malabsorption to lead to an excessive oxalate absorption and acute kidney injury (AKI), especially in subjects with pre-existing renal impairment. Further, it emphasizes the importance of kidney biopsy to facilitate early diagnosis and treatment.

Resolution of C1q deposition but not of the clinical nephrotic syndrome after immunomodulating therapy in focal sclerosis.

BACKGROUND: The natural evolution of C1q nephropathy (C1qNP) during immunosuppressive treatment is relatively little studied or understood. CASE PRESENTATION: A 30 year-old Caucasian female was referred to us for further management of biopsy-proven C1qNP and severe nephrotic syndrome. Serologic work-up remained negative, including complement C3 and C4 levels and repeated testing for antinuclear antibodies. A renal biopsy revealed minimal change nephropathy vs. focal sclerosis on light microscopy and C1qNP on immunopathology. She has failed trials of high-dose oral prednisone, mycophenolate mofetil 1,500 mg twice a day and a subsequent regimen of monthly IV cyclophosphamide 750 mg × 9 cycles. She also received the maximum tolerated angiotensin-converting enzyme inhibitor and spironolactone therapy. Random urine protein-to-creatinine (UPC) ratio predicted proteinuria in the range between 5-35 gm/day, while serum creatinine rose progressively from 1.0 mg/dL to 1.4 mg/dL (to convert to µmol/L, multiply by 88.4). A decision was made to repeat renal biopsy to reassess the underlying histology. The biopsy revealed focal sclerosis but no C1q deposition. CONCLUSIONS: Our case illustrates at least two points: first, an established pathologic diagnosis does not obviate the need for repeated renal biopsy later on, should diagnostic uncertainty persist. Second, histological diagnoses may evolve over time, especially in a patient receiving active and powerful immune-modulating treatment. In our case, the clinical nephrosis did not change with immunosuppressive therapy while C1q deposition ceased, making this latter entity likely the immunologically mediated process.

Regulation of neuropeptide Y in the rat amygdala following unilateral olfactory bulbectomy.

While the mechanisms are not fully understood, olfactory bulbectomy (OBX) is a well-known rat model of depression and depression-related disorders such as anxiety and aggression. Alterations in neuropeptide Y (NPY) levels in the brain have been linked to depression and have been shown to be involved in the response to stress. This study explored the possible regulation of NPY immunoreactivity in specific regions of the amygdala 14 days after OBX in adult male Sprague-Dawley rats (n=6). Unilateral OBX and immunohistochemistry permitted comparisons of NPY in the ipsilateral amygdala with NPY in the contralateral (sham) amygdala. OBX resulted in significant increases (P<0.05) in NPY immunoreactivity in the anterior medial amygdala (threefold) and the posterior medial amygdala (2.5-fold). These regions receive projections from the accessory olfactory bulb (AOB). In contrast, the anterior and posterolateral cortical nuclei of the amygdala receive projections from the main olfactory bulb (MOB). NPY was not increased in these nuclei. These data show that not only does OBX increase NPY immunoreactivity in the amygdala, but also suggest that the AOB plays a prominent role in this regulation.

Desmopression is an effective adjunct treatment for reversing excessive hyponatremia overcorrection.

We report a case of a 50-year-old malnourished African American male with hiccups, nausea and vomiting who was brought to the Emergency Department after repeated seizures at home. Laboratory evaluations revealed sodium (Na(+)) 107 mmol/L, unmeasurably low potassium, chloride < 60 mmol/L, bicarbonate of 38 mmol/L and serum osmolality 217 mOsm/kg. Seizures were controlled with 3% saline IV. Once nausea was controlled with iv antiemetics, he developed large volume free water diuresis with 6 L of dilute urine in 8 h (urine osmolality 40-60 mOsm/kg) and serum sodium rapidly rose to 126 mmol/L in 12 h. Both intravenous desmopressin and 5% dextrose in water was given to achieve a concentrated urine and to temporarily reverse the acute rise of sodium, respectively. Serum Na(+) was gradually re-corrected in 2-3 mmol/L daily increments from 118 mmol/L until 130 mmol/L. Hypokalemia was slowly corrected with resultant auto-correction of metabolic alkalosis. The patient discharged home with no neurologic sequaele on the 11(th) hospital day. In euvolemic hyponatremic patients, controlling nausea may contribute to unpredictable free water diuresis. The addition of an antidiuretic hormone analog, such as desmopressin can limit urine output and prevent an unpredictable rise of the serum sodium.

Lumbar plexus block via a femoral approach for total hip arthroplasty dislocation reduction: a report of 2 cases.

The incidence of hip dislocation can vary based on factors including age and patient co-morbidities. Prosthetic hip dislocations present a particularly difficult challenge. Although many cases are treated in the emergency setting using procedural sedation for reduction, some may require general anesthesia. We report two cases in which lumbar plexus blockade was used as the primary means for successful hip prosthesis dislocation reduction.