Relationship Between the Anion Gap and Serum Lactate in Hypovolemic Shock.

Background and objectives: Previous studies evaluating patients in the Intensive Care Unit with established lactic acidosis determined that the anion gap is an insensitive screening tool for elevated blood lactate. No prior study has examined the relationship between anion gap and serum lactate within the first hours of the development of lactic acidosis. Design, setting, participants, & measurements: Data were obtained prospectively from a convenience sample of adult trauma patients at a single level 1 trauma center. Venous samples were drawn prior to initiation of intravenous fluid resuscitation. A linear regression model was constructed to assess the relationship between serum lactate and anion gap, and 95% prediction intervals were computed. Logistic regression models were constructed to determine the sensitivity and specificity for several different anion gap and lactate cutpoints. Results: 128 patients with elevated serum lactate levels (>2.1 mmol/L) and 63 patients with normal serum lactate levels (< 2.1 mmol/L) were included. The sensitivity of an elevated anion gap (> 10) to reveal hyperlactatemia was only 43% whereas specificity was 84%. Sensitivity improved if the upper limit of normal anion gap was lowered and with increasing levels of serum lactate. The coefficient of determination between serum lactate level and AG yielded an R2 of 0.30 (p < 0.001) and the slope of this relationship was 2.185 with a 95% confidence interval of 2.011-2.359. The mean 95% prediction interval was + 8.9. Conclusions: Within the first hour of the development of lactic acidosis due to hypovolemic shock, the anion gap was not a sensitive indicator of an elevated serum lactate level, but it was fairly specific. The anion gap increased to a greater extent than the serum lactate, the 95% mean prediction interval was wide and approximately 70% of the change in anion gap could not be explained by increases in serum lactate, suggesting that other anions contribute to the anion gap in lactic acidosis.

The Δ Anion Gap/Δ Bicarbonate Ratio in Early Lactic Acidosis: Time for Another Delta?

Background: The ratio of Δ anion gap and Δ bicarbonate (ΔAG/ΔHCO3) is used to detect coexisting acid-base disorders in patients with high anion gap metabolic acidosis. Classic teaching holds that, in lactic acidosis, the ΔAG/ΔHCO3 is 1:1 within the first few hours of onset and subsequently rises to 1.8:1. However, this classic 1:1 stoichiometry in early lactic acidosis was derived primarily from animal models and only limited human data. The objective of this study was to examine the ΔAG/ΔHCO3 within the first hours of the development of lactic acidosis. Methods: Data were obtained prospectively from a convenience sample of adult (age >18 years) trauma-designated patients at a single level-1 trauma center. Venous samples, including a chemistry panel and serum lactate, were drawn before initiation of intravenous fluid resuscitation. Results: A total of 108 patients were included. Of these, 63 patients had normal serum lactate levels (≤2.1 mmol/L) with a mean AG of 7.1 mEq/L, the value used to calculate subsequent ΔAG values. ΔAG/ΔHCO3 was calculated for 45 patients who had elevated serum lactate levels (>2.1 mmol/L). The mean ΔAG/ΔHCO3 for all patients with elevated serum lactate levels was 1.86 (SD, 1.40). Conclusions: The mean ΔAG/ΔHCO3 was 1.86 within the first hours of the development of lactic acidosis due to hypovolemic shock, confirming a small prior human study. This contradicts the traditional belief that, in lactic acidosis, the ΔAG/ΔHCO3 is 1:1 within the first several hours. The classic 1:1 stoichiometry was determined on the basis of animal models in which lactic acid is infused into the extracellular space, facilitating extracellular buffering of protons by bicarbonate. In contrast, our results demonstrate a higher initial ΔAG/ΔHCO3 ratio in early endogenous lactic acidosis in humans. Our analysis indicates this is likely due to unmeasured anions contributing to an elevation in AG.

Public Performance Metrics: Driving Physician Motivation and Performance.

INTRODUCTION: As providers transition from "fee-for-service" to "pay-for-performance" models, focus has shifted to improving performance. This trend extends to the emergency department (ED) where visits continue to increase across the United States. Our objective was to determine whether displaying public performance metrics of physician triage data could drive intangible motivators and improve triage performance in the ED. METHODS: This is a single institution, time-series performance study on a physician-in-triage system. Individual physician baseline metrics-number of patients triaged and dispositioned per shift-were obtained and prominently displayed with identifiable labels during each quarterly physician group meeting. Physicians were informed that metrics would be collected and displayed quarterly and that there would be no bonuses, punishments, or required training; physicians were essentially free to do as they wished. It was made explicit that the goal was to increase the number triaged, and while the number dispositioned would also be displayed, it would not be a focus, thereby acting as this study's control. At the end of one year, we analyzed metrics. RESULTS: The group's average number of patients triaged per shift were as follows: Q1-29.2; Q2-31.9; Q3-34.4; Q4-36.5 (Q1 vs Q4, p < 0.00001). The average numbers of patients dispositioned per shift were Q1-16.4; Q2-17.8; Q3-16.9; Q4-15.3 (Q1 vs Q4, p = 0.14). The top 25% of Q1 performers increased their average numbers triaged from Q1-36.5 to Q4-40.3 (ie, a statistically insignificant increase of 3.8 patients per shift [p = 0.07]). The bottom 25% of Q1 performers, on the other hand, increased their averages from Q1-22.4 to Q4-34.5 (ie, a statistically significant increase of 12.2 patients per shift [p = 0.0013]). CONCLUSION: Public performance metrics can drive intangible motivators (eg, purpose, mastery, and peer pressure), which can be an effective, low-cost strategy to improve individual performance, achieve institutional goals, and thrive in the pay-for-performance era.

Assessing Acid-Base Status in Circulatory Failure: Relationship Between Arterial and Peripheral Venous Blood Gas Measurements in Hypovolemic Shock.

BACKGROUND AND OBJECTIVES: In severe circulatory failure agreement between arterial and mixed venous or central venous values is poor; venous values are more reflective of tissue acid-base imbalance. No prior study has examined the relationship between peripheral venous blood gas (VBG) values and arterial blood gas (ABG) values in hemodynamic compromise. The objective of this study was to examine the correlation between hemodynamic parameters, specifically systolic blood pressure (SBP) and the arterial-peripheral venous (A-PV) difference for all commonly used acid-base parameters (pH, Pco 2, and bicarbonate). DESIGN, SETTING, PARTICIPANTS, AND MEASUREMENTS: Data were obtained prospectively from adult patients with trauma. When an ABG was obtained for clinical purposes, a VBG was drawn as soon as possible. Patients were excluded if the ABG and VBG were drawn >10 minutes apart. RESULTS: The correlations between A-PV pH, A-PV Pco 2, and A-PV bicarbonate and SBP were not statistically significant (P = .55, .17, and .09, respectively). Although patients with hypotension had a lower mean arterial and peripheral venous pH and bicarbonate compared to hemodynamically stable patients, mean A-PV differences for pH and Pco 2 were not statistically different (P = .24 and .16, respectively) between hypotensive and normotensive groups. CONCLUSIONS: In hypovolemic shock, the peripheral VBG does not demonstrate a higher CO2 concentration and lower pH compared to arterial blood. Therefore, the peripheral VBG is not a surrogate for the tissue acid-base status in hypovolemic shock, likely due to peripheral vasoconstriction and central shunting of blood to essential organs. This contrasts with the selective venous respiratory acidosis previously demonstrated in central venous and mixed venous measurements in circulatory failure, which is more reflective of acid-base imbalance at the tissue level than arterial blood. Further work needs to be done to better define the relationship between ABG and both central and peripheral VBG values in various types of shock.

Migrating from One Comprehensive Commercial EHR to Another: Perceptions of Front-line Clinicians and Staff.

As healthcare organizations continue to grow and evolve, migrations from one commercial electronic health record (EHR) system to another are likely to become more common. However, little is known about front-line clinicians' and staff's perceptions of such changes. Our study addresses this gap through an organization-wide survey of employees immediately prior to the transition to a new commercial EHR. We found that almost all front-line clinicians and staff were aware of the upcoming migration, and that most felt positive or neutral about the change, with only about 11% indicating that they were uncomfortable with the migration. Reasons for discomfort included the beliefs that the new EHR will be more time consuming to use and that moving to a new EHR is too costly, as well as concerns about the migration process. Attitudes differed by demographic characteristics and satisfaction with the current EHR. We discuss the implications of these results.

A Comparison of Urolithiasis in the Presence and Absence of Microscopic Hematuria in the Emergency Department.

INTRODUCTION: Urolithiasis is a common medical condition that accounts for a large number of emergency department (ED) visits each year and contributes significantly to annual healthcare costs. Urinalysis is an important screening test for patients presenting with symptoms suspicious for urolithiasis. At present there is a paucity of medical literature examining the characteristics of ureteral stones in patients who have microscopic hematuria on urinalysis versus those who do not. The purpose of this study was to examine mean ureteral stone size and its relationship to the incidence of clinically significant hydronephrosis in patients with and without microscopic hematuria. METHODS: This is a retrospective chart review of patient visits to a single, tertiary academic medical center ED between July 1, 2008, and August 1, 2013, of patients who underwent non-contrast computed tomography of the abdomen and pelvis and urinalysis. For patient visits meeting inclusion criteria, we compared mean stone size and the rate of moderate-to-severe hydronephrosis found on imaging in patients with and without microscopic hematuria on urinalysis. RESULTS: Out of a total of 2,370 patient visits 393 (16.6%) met inclusion criteria. Of those, 321 (82%) had microscopic hematuria present on urinalysis. Patient visits without microscopic hematuria had a higher rate of moderate-to-severe hydronephrosis (42%), when compared to patients with microscopic hematuria present (25%, p=.005). Mean ureteral stone size among patient visits without microscopic hematuria was 5.7 mm; it was 4.7 mm for those patients with microscopic hematuria (p=.09). For ureteral stones 5 mm or larger, the incidence of moderate-to-severe hydronephrosis was 49%, whereas for ureteral calculi less than 5 mm in size, the incidence of moderate-to-severe hydronephrosis was 14% (p < 0.0001). CONCLUSION: Patients visiting the ED with single-stone ureterolithiasis without microscopic hematuria on urinalysis could be at increased risk of having moderate-to-severe hydronephrosis compared to similar patients presenting with microscopic hematuria on urinalysis. Although the presence of hematuria on urinalysis is a moderately sensitive screening test for urolithiasis, these results suggest patients without hematuria tend to have more clinically significant ureteral calculi, making their detection more important. Clinicians should maintain a high index of suspicion for urolithiasis, even in the absence of hematuria, since ureteral stones in these patients were found to be associated with a higher incidence of obstructive uropathy.

Understanding Patient Questions about their Medical Records in an Online Health Forum: Opportunity for Patient Portal Design.

There are many benefits of online patient access to their medical records through technologies such as patient portals. However, patients often have difficulties understanding the clinical data presented in portals. In response, increasingly, patients go online to make sense of this data. One commonly used online resource is health forums. In this pilot study, we focus on one type of clinical data, laboratory results, and one popular forum, MedHelp. We examined patient question posts that contain laboratory results to gain insights into the nature of these questions and of the answers. Our analyses revealed a typology of confusion (i.e., topics of their questions) and potential gaps in traditional healthcare supports (i.e., patients' requests and situational factors), as well as the supports patients may gain through the forum (i.e., what the community provides). These results offer preliminary evidence of opportunities to redesign patient portals, and will inform our future work.

Prospective correlation of arterial vs venous blood gas measurements in trauma patients.

OBJECTIVE: The objective of this study is to assess if venous blood gas (VBG) results (pH and base excess [BE]) are numerically similar to arterial blood gas (ABG) in acutely ill trauma patients. METHODS: We prospectively correlated paired ABG and VBG results (pH and BE) in adult trauma patients when ABG was clinically indicated. A priori consensus threshold of clinical equivalence was set at ± less than 0.05 pH units and ± less than 2 BE units. We hypothesized that ABG results could be predicted by VBG results using a regression equation, derived from 173 patients, and validated on 173 separate patients. RESULTS: We analyzed 346 patients and found mean arterial pH of 7.39 and mean venous pH of 7.35 in the derivation set. Seventy-two percent of the paired sample pH values fell within the predefined consensus equivalence threshold of ± less than 0.05 pH units, whereas the 95% limits of agreement (LOAs) were twice as wide, at -0.10 to 0.11 pH units. Mean arterial BE was -2.2 and venous BE was -1.9. Eighty percent of the paired BE values fell within the predefined ± less than 2 BE units, whereas the 95% LOA were again more than twice as wide, at -4.4 to 3.9 BE units. Correlations between ABG and VBG were strong, at r(2) = 0.70 for pH and 0.75 for BE. CONCLUSION: Although VBG results do correlate well with ABG results, only 72% to 80% of paired samples are clinically equivalent, and the 95% LOAs are unacceptably wide. Therefore, ABG samples should be obtained in acutely ill trauma patients if accurate acid-base status is required.

Echocardiography to supplement stress electrocardiography in emergency department chest pain patients.

INTRODUCTION: Chest pain (CP) patients in the Emergency Department (ED) present a diagnostic dilemma, with a low prevalence of coronary disease but grave consequences with misdiagnosis. A common diagnostic strategy involves ED cardiac monitoring while excluding myocardial necrosis, followed by stress testing. We sought to describe the use of stress echocardiography (echo) at our institution, to identify cardiac pathology compared with stress electrocardiography (ECG) alone. METHODS: Retrospective cohort study of 57 urban ED Chest Pain Unit (CPU) patients from 2002-2005 with stress testing suggesting ischemia. Our main descriptive outcome was proportion and type of discordant findings between stress ECG testing and stress echo. The secondary outcome was whether stress echo results appeared to change management. RESULTS: Thirty-four of 57 patients [59.7%, 95% confidence interval (CI) 46.9-72.4%] had stress echo results discordant with stress ECG results. The most common discordance was an abnormal stress ECG with a normal stress echo (n=17/57, 29.8%, CI 17.9-41.7%), followed by normal stress ECG but with reversible regional wall-motion abnormality on stress echo (n = 10/57, 17.5%, CI 7.7-27.4%). The remaining seven patients (12.3%, CI 3.8-20.8%) had non-diagnostic stress ECG due to sub-maximal effort. Stress echo showed reversible wall-motion abnormality in two, and five were normal. Twenty-five of the 34 patients (73.5%, CI 56.8-85.4%) with discordant results had a different diagnostic strategy than predicted from their stress ECG alone. CONCLUSION: The addition of echo to stress ECG testing in ED CPU patients altered diagnosis in 34/57 (59.7%, CI 46.9-72.4%) patients, and appeared to change management in 25/57 (43.9%, CI 31.8-57.6%) patients.

Improving service quality by understanding emergency department flow: a White Paper and position statement prepared for the American Academy of Emergency Medicine.

Emergency Department (ED) crowding is a common problem in the United States and around the world. Process reengineering methods can be used to understand factors that contribute to crowding and provide tools to help alleviate crowding by improving service quality and patient flow. In this article, we describe the ED as a service business and then discuss specific methods to improve the ED quality and flow. Methods discussed include demand management, critical pathways, process-mapping, Emergency Severity Index triage, bedside registration, Lean and Six Sigma management methods, statistical forecasting, queuing systems, discrete event simulation modeling and balanced scorecards. The purpose of this review is to serve as a background for emergency physicians and managers interested in applying process reengineering methods to improving ED flow, reducing waiting times, and maximizing patient satisfaction. Finally, we present a position statement on behalf of the American Academy of Emergency Medicine addressing these issues.

The worsening of ED on-call coverage in California: 6-year trend.

To reassess problems with on-call physician coverage in California, we repeated our anonymous 2000 survey of the California chapter of the American College of Emergency Physicians. Physicians responded from 77.4% of California emergency departments (EDs), 51.0% of ED directors, and 34% of those surveyed. Of 21 specialties, on-call availability worsened since 2000 for 9, was unchanged for 11, and improved for 1. Of ED directors, 54% report medical staff rules require on-call duty, down from 72% in 2000. Hospitals have increased specialist on-call payments (from 21% to 35%, with 75% paying at least one specialty). Most emergency physicians (80.3%) report insurance status negatively affects on-call physician responsiveness, up from 42% in 2000. Emergency departments with predominantely minority or uninsured patients had fewer specialists and more trouble accessing them. Insurance status has a major negative effect on ED consultation and follow-up care. The on-call situation in California has worsened substantially in 6 years.

Positive cerebrospinal fluid cultures after normal cell counts are contaminants.

Previous literature on meningitis reports that cerebrospinal fluid (CSF) culture contaminants are threefold more common than true pathogens. Clinical follow-up of patients with CSF contaminants is costly, time-consuming, and potentially unnecessary. In this study, we hypothesized that, in immunocompetent Emergency Department (ED) patients with normal CSF cell counts and negative Gram stains, all positive bacterial cultures are contaminants and patient follow-up is unnecessary. We retrospectively reviewed 191 ED charts of patients with positive CSF cultures over 5 years. We abstracted lumbar puncture results, disposition, and follow-up activities, and determined monetary charges. There were 137 patients (72%) who met inclusion criteria with CSF white blood cells < or = 7 microL, negative Gram stain, and immunocompetence. Ninety-eight were discharged from the ED and 39 were admitted to the hospital for reasons other than meningitis. All 137 positive cultures were found to be contaminants, with coagulase-negative staphylococci found most commonly. Follow-up activities included telephone calls (49%), repeat ED visits (13%), repeat lumbar punctures (9%), unnecessary antibiotic treatment (6%), and hospitalizations (6%), generating $55,000 in charges. Follow-up may be unnecessary in ED patients with positive bacterial CSF cultures who were discharged from the ED, if their initial lumbar punctures were normal.

Can ED staff accurately estimate the weight of adult patients?

PURPOSE: The purpose of the study was to determine the accuracy of adult weight estimates by emergency department personnel. BASIC PROCEDURES: This was a prospective, nonrandomized, observational study in a university tertiary referral center. All patient care staff and all adult patients were eligible. Patients were weighed at the bedside, then staff were asked individually for estimates. Data were analyzed using SPSS general linear modeling procedures (SPSS, Chicago, IL) to obtain a generalized analysis of variance. MAIN FINDINGS: Eighty-seven staff provided 957 estimates on 241 patients. Providers were within 5% of true weight on 33% of estimates (95% confidence interval [CI], 28-38). In our a priori subgroups, a significant difference was noted only for body mass index (BMI); percentages of correct estimates were 16% (95% CI, 0-33; n = 33) for BMI < 18.5; 38% (95% CI, 33-43; n = 654) for 18.5 < or = BMI < or = 30; and 23% (95% CI, 17-30; n = 270) for BMI > 30 (P < .001). PRINCIPAL CONCLUSIONS: Emergency department personnel provided accurate weights in only 33% of estimates. Estimates became significantly less accurate in underweight and obese patients (defined by BMI).

Personal digital assistants change management more often than paper texts and foster patient confidence.

INTRODUCTION: Rapid retrieval of information, including drug treatment options, is critical to emergency department practice. OBJECTIVES: To assess feasibility and patient acceptance of personal digital assistants and to determine the scope of management changes. METHODS: Emergency medicine residents (EMRs, n = 18) and emergency medicine attending (EMAs, n = 12) used personal digital assistants with drug database and clinical references. Text versions were also available in the emergency department. We did a prospective, random, cross-over time-motion study, recording retrieval time, source, and changes to patient care for 16 and 8 h for EMRs and EMAs, respectively. We surveyed patients for confidence in EMRs and EMAs with personal digital assistants, and perceived efficiency. RESULTS: EMRs accessed paper (n = 131) or personal digital assistant (n = 181) information on 92.3% of patients (n = 17, both). They accessed personal digital assistant on 61.4% of patients vs. 44.5% with texts (odds ratio 1.99, 95% confidence interval 1.4-2.80). Mean access times were 9.3 and 9.4 s, respectively, +1.4 for both. Personal digital assistant access was 75%/25% between pharmacopeia and clinical resource. Personal digital assistants changed drug choice in 39/181 patients (21.5%), and other management (diagnosis, treatment or disposition) in 15/181 patients (8.3%). Odds ratio for change in management for personal digital assistant vs. paper was 2.00 (95% confidence interval 1.11-3.60). We surveyed patient perception for 198 of 295 patients (67.1%). Fifty percent reported more confidence in their EMRs and EMAs with a personal digital assistant, while 5% reported less confidence. Sixty percent agreed strongly that there is too much medical information to remember. CONCLUSIONS: Personal digital assistants are feasible in an academic emergency department and change management more often than texts. EMRs accessed personal digital assistants more often than paper texts. Patient perceptions of physicians who use personal digital assistants are neutral or favorable.

The Frequency of Reevaluation or Peak Flow Meter Documentation in Acute Asthma Exacerbations in the Emergency Department: Are We Treating in Accordance with NIH/NAEPP Guidelines?

OBJECTIVES: To evaluate the frequency of peak expiratory flow rate (PEFR) measurement and clinical re-evaluation in the management of ED asthmatic patients. METHODS: This was a retrospective chart review examining consecutive asthma patients who presented to the University of California Irvine ED between September 1, 2003 and December 31, 2003. Patients were excluded if they had a diagnosis of COPD, lung cancer, pneumonia, congestive heart failure, alpha 1 anti-trypsin deficiency or were under 5 years of age. Data collected included patient demographics, pulse oximetry reading(s), ED treatments rendered, and frequencies of PEFR measurement (pre and post therapy), of clinical re-evaluations in the ED, and of ED return visits. RESULTS: Of the 122 ED visits from 111 patients, 11 (10%) patients returned during the 4 month study period, with 5 patients (4.5%) returning in less than 72 hours. Seven (6.0%) patients had PEFR done both pre and post treatment and 24 (20%) had one or more PEFR performed either before or after treatment. Only 61 (50%) of the visits had a documented clinical re-evaluation prior to disposition. CONCLUSIONS: Despite their documented role in asthma treatment algorithms, PEFR was performed infrequently and clinical re-evaluation was documented in only half of cases. Recommended algorithms for asthma management were not commonly followed in this academic ED.

The state of ED on-call coverage in California.

The ED provides initial treatment, but failure of specialists to respond unravels the safety net. To assess the scope of problems with on-call physicians in California. A mailed anonymous survey to all CAL/ACEP physician members (1876) asking patient, physician and ED demographics, specialist availability for consultation, insurance profile, and availability of follow-up care. 608/1876 physicians responded (32.4%), representing 320/353 California EDs (90.6%). The seven specialties in which the greatest proportion of EDs reported trouble with specialty response were: plastic surgery (37.5%), ENT (35.9%), dentistry (34.9%), psychiatry (26.0%), neurosurgery (22.9%), ophthalmology (18.4%) and orthopedics (18.0%). 71.6% of responder EDs reported that their medical staff rules required ED on-call coverage. However, the percentage of responders who stated that hospitals paid each specialty for call was low: neurosurgery (37.3%), orthopedics (34.4%), ENT (17.9%), plastic surgery (15.1%) and ophthalmology (13.1%). On-call problems were more acute at night (77.2%) or on weekends (72.4%). Patient insurance negatively affected (69.9%) willingness of on-call physicians to consult for at least a quarter of patients. Regarding follow-up, 91% reported some trouble, whereas 64% reported a problem at least half the time. Surgical sub-specialists are the most problematic on-call physicians. Insurance status has a major negative effect on ED and follow-up care. The on-call situation in California has reached crisis proportions.

Antiemetic use in pediatric gastroenteritis: a national survey of emergency physicians, pediatricians, and pediatric emergency physicians.

The objective of this study was to review the use of antiemetics for pediatric gastroenteritis and to determine prescribing patterns of physicians. A mailed cross-sectional survey instrument was sent to randomly selected board-certified emergency medicine, pediatric, and pediatric emergency medicine specialists. A total of 1665 surveys were mailed, with 593 completed surveys returned (35.6% response rate). A majority of responders (60.9%) reported using antiemetics for pediatric gastroenteritis at least once in the past year, with a greater than 50% usage for all three specialty groups. Promethazine was the most commonly used antiemetic in all specialties, and per rectum the most common route of administration. Adverse reactions following a single dose of antiemetic were most frequently reported with prochlorperazine. The most common reason for antiemetic use was to prevent further dehydration. The most common concern regarding antiemetic use was potential for side effects. Occasional antiemetic use appears to be a common practice in treating pediatric gastroenteritis, regardless of specialty. Given the absence of literature on efficacy or safety, these drugs should be used only with careful consideration to potential side effects.