A single-cell atlas of human and mouse white adipose tissue.

White adipose tissue, once regarded as morphologically and functionally bland, is now recognized to be dynamic, plastic and heterogenous, and is involved in a wide array of biological processes including energy homeostasis, glucose and lipid handling, blood pressure control and host defence1. High-fat feeding and other metabolic stressors cause marked changes in adipose morphology, physiology and cellular composition1, and alterations in adiposity are associated with insulin resistance, dyslipidemia and type 2 diabetes2. Here we provide detailed cellular atlases of human and mouse subcutaneous and visceral white fat at single-cell resolution across a range of body weight. We identify subpopulations of adipocytes, adipose stem and progenitor cells, vascular and immune cells and demonstrate commonalities and differences across species and dietary conditions. We link specific cell types to increased risk of metabolic disease and provide an initial blueprint for a comprehensive set of interactions between individual cell types in the adipose niche in leanness and obesity. These data comprise an extensive resource for the exploration of genes, traits and cell types in the function of white adipose tissue across species, depots and nutritional conditions.

The Effect of Lateral Pharyngeal Collapse Patterns on Therapy Response in Upper Airway Stimulation Surgery.

OBJECTIVES: Obstructive sleep apnea (OSA) is characterized by repeated upper airway collapse while sleeping which leads to intermittent hypoxemia. Upper airway stimulation (UAS) is a commonly practiced modality for treating OSA in patients who cannot tolerate, or do not benefit from, positive airway pressure (PAP). The purpose of this study is to identify the effect of lateral pharyngeal collapse patterns on therapy response in UAS. METHODS: A retrospective cohort study from a single, tertiary-care academic center was performed. Patients who underwent UAS between October 2016 and July 2019 were identified and analyzed. Drug-induced Sleep Endoscopy (DISE) outcomes between Apnea-Hypopnea Index (AHI) responders and AHI non-responders were compared. Those with complete concentric collapse at the velopharynx were not candidates for UAS. RESULTS: About 95 patients that underwent UAS were included in this study. Pre- to Post-UAS demonstrated significant improvements in Epworth Sleepiness Scale (12.0 vs 4.0, P = .001), AHI (29.8 vs 5.4, P < .001) and minimum oxygen saturation (79% vs 83%, P < .001). No DISE findings significantly predicted AHI response after UAS. Specifically, multiple types of lateral pharyngeal collapse patterns did not adversely effect change in AHI or AHI response rate. CONCLUSION: Demonstration of lateral pharyngeal collapse on DISE, in the absence of complete concentric velopharyngeal obstruction, does not appear to adversely affect AHI outcomes in UAS patients. LEVEL OF EVIDENCE: VI.

Evaluation of Surgical Learning Curve Effect on Obstructive Sleep Apnea Outcomes in Upper Airway Stimulation.

OBJECTIVE: An increasing number of facilities offer Upper Airway Stimulation (UAS) with varying levels of experience. The goal was to quantify whether a surgical learning curve exists in operative or sleep outcomes in UAS. METHODS: International multi-center retrospective review of the ADHERE registry, a prospective international multi-center study collecting UAS outcomes. ADHERE registry centers with at least 20 implants and outcomes data through at least 6-month follow-up were reviewed. Cases were divided into two groups based on implant order (the first 10 or second 10 consecutive implants at a given site). Group differences were assessed using Mann-Whitney U-tests, Chi-squared tests, or Fisher's Exact tests, as appropriate. A Mann-Kendall trend test was used to detect if there was a monotonic trend in operative time. Sleep outcome equivalence between experience groups was assessed using the two one-sided tests approach. RESULTS: Thirteen facilities met inclusion criteria, contributing 260 patients. Complication rates did not significantly differ between groups (P = .808). Operative time exhibited a significant downward trend (P < .001), with the median operative time dropping from 150 minutes for the first 10 implants to 134 minutes for the subsequent 10 implants. The decrease in AHI from baseline to 12-month follow-up was equivalent between the first and second ten (22.8 vs 21.2 events/hour, respectively, P < .001). Similarly, the first and second ten groups had equivalent ESS decreases at 6 months (2.0 vs 2.0, respectively, P < .001). ESS outcomes remained equivalent for those with data through 12-months. CONCLUSIONS: Across the centers' first 20 implants, an approximately 11% reduction operative time was identified, however, no learning curve effect was seen for 6-month or 12-month AHI or ESS over the first twenty implants. Ongoing monitoring through the ADHERE registry will help measure the impact of evolving provider and patient specific characteristics as the number of implant centers increases.

Assessment of Factors Impacting Long-Term Utilization of Tracheoesophageal Speech Among Laryngectomees.

OBJECTIVE(S): To evaluate complication rate and abandonment rate after tracheoesophageal puncture and to assess factors associated with these outcome measures. METHODS: Retrospective review of laryngectomy patients seen at a single academic institution between 1/1/2003 and 12/1/2018. Charts reviewed for demographics, medical comorbidities, tumor characteristics, surgical data, adjuvant treatment history, and complications related to laryngectomy or tracheoesophageal puncture. Complications were divided into minor and major. RESULTS: A total of 293 laryngectomees met inclusion criteria. Of these, 69 patients (23.5%) underwent tracheoesophageal puncture. Average follow up was 64.6 months (SD 58.3). Overall laryngectomy complication rate was 43.3%. Overall tracheoesophageal puncture complication rate was 73.9%, with 39.1% of patients having major complications and 34.8% having minor complications only. Total abandonment rate for tracheoesophageal puncture was 34.8%. No associations were seen between tracheoesophageal puncture complication or abandonment rates based on age, gender, race, or insurance status. An increased rate of laryngectomy complications was seen after primary tracheoesophageal puncture (76.5% vs 41.3%, P = .005). CONCLUSION: Tracheoesophageal puncture outcomes were similar in patients with varied demographic, medical, and treatment backgrounds. When considering timing, our findings suggest that patients should be counseled on the possibility of increased complication risk after primary tracheoesophageal puncture. In those in whom the surgeon already has concerns about wound healing, it may be prudent to avoid primary tracheoesophageal puncture. The relatively high abandonment rate emphasizes the value of this measure of tracheoesophageal puncture outcome and highlights the need for appropriate patient counseling and prospective studies assessing the decision to abandon.

Delayed Multifocal Tracheal Injury Following Thyroidectomy: A Case Report and Review of the Literature.

Delayed presentation of tracheal injury after thyroidectomy is a rare complication. We present the case of a 24-year-old male presenting with findings of tracheal injury 12 days after total thyroidectomy. Upon surgical exploration, multifocal, transmural tracheal injuries were identified. Repair was performed with a combination of acellular dermal matrix allograft, local-regional flaps, silicone stenting, and tracheostomy. Herein we also review published cases of delayed tracheal injury. Our findings suggest that delayed tracheal necrosis and rupture is an uncommon yet potentially devastating complication of thyroidectomy. Surgeons should maintain a low threshold to suspect such injuries when patients present with neck swelling and subcutaneous emphysema, even up to 40 days post-operatively. Complex injuries may require a multidisciplinary approach and an armamentarium of reconstructive techniques.

Postoperative Opioid Use and Pain Management Following Otologic and Neurotologic Surgery.

OBJECTIVES: The topic of prescription opioid overuse remains a growing concern in the United States. Our objective is to provide insight into pain perception and opioid use based on a patient cohort undergoing common otologic and neurotologic surgeries. STUDY DESIGN: Prospective observational study with patient questionnaire. SETTING: Single academic medical center. SUBJECTS AND METHODS: Adult patients undergoing otologic and neurotologic procedures by two fellowship trained neurotologists between June and November of 2018 were included in this study. During first postoperative follow-up, participants completed a questionnaire assessing perceived postoperative pain and its impact on quality of life, pain management techniques, and extent of prescription opioid use. RESULTS: A total of 47 patients met inclusion and exclusion criteria. The median pain score was 3 out of 10 (Interquartile Range [IQR] = 2-6) with no significant gender differences (P = .92). Patients were prescribed a median of 15.0 (IQR = 10.0-15.0) tablets of opioid pain medication postoperatively, but only used a median of 4.0 (IQR = 1.0-11.5) tablets at the time of first follow-up. Measured quality of life areas included sleep, physical activity, work, and mood. Sleep was most commonly affected, with 69.4% of patients noting disturbances. CONCLUSIONS: This study suggests that practitioners may over-estimate the need for opioid pain medication following otologic and neurotologic surgery. It also demonstrates the need for ongoing patient education regarding opioid risks, alternatives, and measures to prevent diversion.

Using Individual Clinical Evaluations to Assess Residents' Clinical Judgment; Feasibility and Residents' Perception.

OBJECTIVE: In surgical training, most assessment tools focus on advanced clinical decision-making or operative skill. Available tools often require significant investment of resources and time. A high stakes oral examination is also required to become board-certified in surgery. We developed Individual Clinical Evaluation (ICE) to evaluate intern-level clinical decision-making in a time- and cost-efficient manner, and to introduce the face-to-face evaluation setting. DESIGN: Intern-level ICE consists of 3 clinical scenarios commonly encountered by surgical trainees. Each scenario was developed to be presented in a step-by-step manner to an intern by an attending physician or chief resident. The interns had 17 minutes to complete the face-to-face evaluation and 3 minutes to receive feedback on their performance. The feedback was transcribed and sent to the interns along with incorrect answers. Eighty percent correct was set as a minimum to pass each scenario and continue with the next one. Interns who failed were retested until they passed. Frequency of incorrect response was tracked by question/content area. After passing the 3 scenarios, interns completed a survey about their experience with ICE. SETTING: Beth Israel Deaconess Medical Center, an academic tertiary care facility located in Boston, Massachusetts. PARTICIPANTS: All first-year surgery residents in our institution (n = 17) were invited to complete a survey. RESULTS: All 2016-2017 surgical interns (17) completed the ICEs. A total of $171 (US) was spent conducting the ICEs, and an average of 17 minutes was used to complete each evaluation. In total, 5 different residents failed 1 scenario, with the most common mistake being: failing to stabilize respiration before starting management. After completing the 3 clinical scenarios, more than 90% of respondents agreed or strongly agreed that the evaluations were appropriately challenging for training level, and that the evaluations helped to identify personal strengths and weaknesses in skill and knowledge. The majority believed their knowledge improved as a result of the ICE and felt better prepared to manage these scenarios (88% and 76%, respectively). CONCLUSIONS: The ICE is an inexpensive and time efficient way to introduce interns to board type examinations and assess their preparedness for perioperative patient care issues. Common errors were identified which were able to inform educational efforts. ICEs were well accepted by residents. Next steps include extension of the ICE to PGY2 and PGY3 residents.

Rapid Identification of a Cooling Tower-Associated Legionnaires' Disease Outbreak Supported by Polymerase Chain Reaction Testing of Environmental Samples, New York City, 2014-2015.

We investigated an outbreak of eight Legionnaires' disease cases among persons living in an urban residential community of 60,000 people. Possible environmental sources included two active cooling towers (air-conditioning units for large buildings) <1 km from patient residences, a market misting system, a community-wide water system used for heating and cooling, and potable water. To support a timely public health response, we used real-time polymerase chain reaction (PCR) to identify Legionella DNA in environmental samples within hours of specimen collection. We detected L. pneumophila serogroup 1 DNA only at a power plant cooling tower, supporting the decision to order remediation before culture results were available. An isolate from a power plant cooling tower sample was indistinguishable from a patient isolate by pulsed-field gel electrophoresis, suggesting the cooling tower was the outbreak source. PCR results were available <1 day after sample collection, and culture results were available as early as 5 days after plating. PCR is a valuable tool for identifying Legionella DNA in environmental samples in outbreak settings.

Legionnaires' Disease Outbreaks and Cooling Towers, New York City, New York, USA.

The incidence of Legionnaires' disease in the United States has been increasing since 2000. Outbreaks and clusters are associated with decorative, recreational, domestic, and industrial water systems, with the largest outbreaks being caused by cooling towers. Since 2006, 6 community-associated Legionnaires' disease outbreaks have occurred in New York City, resulting in 213 cases and 18 deaths. Three outbreaks occurred in 2015, including the largest on record (138 cases). Three outbreaks were linked to cooling towers by molecular comparison of human and environmental Legionella isolates, and the sources for the other 3 outbreaks were undetermined. The evolution of investigation methods and lessons learned from these outbreaks prompted enactment of a new comprehensive law governing the operation and maintenance of New York City cooling towers. Ongoing surveillance and program evaluation will determine if enforcement of the new cooling tower law reduces Legionnaires' disease incidence in New York City.

Secondary Organic Aerosol (SOA) from Nitrate Radical Oxidation of Monoterpenes: Effects of Temperature, Dilution, and Humidity on Aerosol Formation, Mixing, and Evaporation.

Nitrate radical (NO3) oxidation of biogenic volatile organic compounds (BVOC) is important for nighttime secondary organic aerosol (SOA) formation. SOA produced at night may evaporate the following morning due to increasing temperatures or dilution of semivolatile compounds. We isothermally dilute the oxidation products from the limonene+NO3 reaction at 25 °C and observe negligible evaporation of organic aerosol via dilution. The SOA yields from limonene+NO3 are approximately constant (∼174%) at 25 °C and range from 81 to 148% at 40 °C. Based on the difference in yields between the two temperatures, we calculated an effective enthalpy of vaporization of 117-237 kJ mol-1. The aerosol yields at 40 °C can be as much as 50% lower compared to 25 °C. However, when aerosol formed at 25 °C is heated to 40 °C, only about 20% of the aerosol evaporates, which could indicate a resistance to aerosol evaporation. To better understand this, we probe the possibility that SOA from limonene+NO3 and ß-pinene+NO3 reactions is highly viscous. We demonstrate that particle morphology and evaporation is dependent on whether SOA from limonene is formed before or during the formation of SOA from ß-pinene. This difference in particle morphology is present even at high relative humidity (∼70%).

A Large Community Outbreak of Legionnaires' Disease Associated With a Cooling Tower in New York City, 2015.

OBJECTIVES: Infections caused by Legionella are the leading cause of waterborne disease outbreaks in the United States. We investigated a large outbreak of Legionnaires' disease in New York City in summer 2015 to characterize patients, risk factors for mortality, and environmental exposures. METHODS: We defined cases as patients with pneumonia and laboratory evidence of Legionella infection from July 2 through August 3, 2015, and with a history of residing in or visiting 1 of several South Bronx neighborhoods of New York City. We describe the epidemiologic, environmental, and laboratory investigation that identified the source of the outbreak. RESULTS: We identified 138 patients with outbreak-related Legionnaires' disease, 16 of whom died. The median age of patients was 55. A total of 107 patients had a chronic health condition, including 43 with diabetes, 40 with alcoholism, and 24 with HIV infection. We tested 55 cooling towers for Legionella, and 2 had a strain indistinguishable by pulsed-field gel electrophoresis from 26 patient isolates. Whole-genome sequencing and epidemiologic evidence implicated 1 cooling tower as the source of the outbreak. CONCLUSIONS: A large outbreak of Legionnaires' disease caused by a cooling tower occurred in a medically vulnerable community. The outbreak prompted enactment of a new city law on the operation and maintenance of cooling towers. Ongoing surveillance and evaluation of cooling tower process controls will determine if the new law reduces the incidence of Legionnaires' disease in New York City.

Photochemical Aging of α-pinene and ß-pinene Secondary Organic Aerosol formed from Nitrate Radical Oxidation.

The nitrate radical (NO3) is the dominant nighttime oxidant in most urban and rural environments and reacts rapidly with biogenic volatile organic compounds to form secondary organic aerosol (SOA) and organic nitrates (ON). Here, we study the formation of SOA and ON from the NO3 oxidation of two monoterpenes (α-pinene and ß-pinene) and investigate how they evolve during photochemical aging. High SOA mass loadings are produced in the NO3+ß-pinene reaction, during which we detected 41 highly oxygenated gas- and particle-phase ON possessing 4 to 9 oxygen atoms. The fraction of particle-phase ON in the ß-pinene SOA remains fairly constant during photochemical aging. In contrast to the NO3+ß-pinene reaction, low SOA mass loadings are produced during the NO3+α-pinene reaction, during which only 5 highly oxygenated gas- and particle-phase ON are detected. The majority of the particle-phase ON evaporates from the α-pinene SOA during photochemical aging, thus exhibiting a drastically different behavior from that of ß-pinene SOA. Our results indicate that nighttime ON formed by NO3+monoterpene chemistry can serve as either permanent or temporary NOx sinks depending on the monoterpene precursor.

Modeling the Current and Future Roles of Particulate Organic Nitrates in the Southeastern United States.

Organic nitrates are an important aerosol constituent in locations where biogenic hydrocarbon emissions mix with anthropogenic NOx sources. While regional and global chemical transport models may include a representation of organic aerosol from monoterpene reactions with nitrate radicals (the primary source of particle-phase organic nitrates in the Southeast United States), secondary organic aerosol (SOA) models can underestimate yields. Furthermore, SOA parametrizations do not explicitly take into account organic nitrate compounds produced in the gas phase. In this work, we developed a coupled gas and aerosol system to describe the formation and subsequent aerosol-phase partitioning of organic nitrates from isoprene and monoterpenes with a focus on the Southeast United States. The concentrations of organic aerosol and gas-phase organic nitrates were improved when particulate organic nitrates were assumed to undergo rapid (τ = 3 h) pseudohydrolysis resulting in nitric acid and nonvolatile secondary organic aerosol. In addition, up to 60% of less oxidized-oxygenated organic aerosol (LO-OOA) could be accounted for via organic nitrate mediated chemistry during the Southern Oxidants and Aerosol Study (SOAS). A 25% reduction in nitrogen oxide (NO + NO2) emissions was predicted to cause a 9% reduction in organic aerosol for June 2013 SOAS conditions at Centreville, Alabama.

Fatal and nonfatal drowning outcomes related to dangerous underwater breath-holding behaviors - New York State, 1988-2011.

Drowning is an important cause of preventable injury and mortality, ranking fifth among leading causes of unintentional injury death in the United States. In 2011, two healthy young men died in a drowning incident at a New York City (NYC)-regulated swimming facility. The men became unconscious underwater after performing intentional hyperventilation before submersion. The phenomenon of healthy swimmers becoming unconscious underwater has been described elsewhere as hypoxic blackout. Prompted by this incident, the NYC Department of Health and Mental Hygiene (DOHMH) in collaboration with the New York State Department of Health (SDOH) conducted a case review of New York state fatal and nonfatal drownings reported during 1988-2011 to investigate similar behaviors in other incidents. DOHMH identified 16 cases, three in NYC, with a consistent set of voluntary behaviors associated with unintentional drowning and designated this class of behaviors as "dangerous underwater breath-holding behaviors" (DUBBs). For this small sample, the frequency of different DUBBs varied by age and swimming level, and practicing more than one DUBB increased the risk for fatality. This research contributes to the literature on drowning by focusing on contributing behaviors rather than drowning outcomes. NYC recently enacted public health education and regulations that discourage DUBBs; these interventions have the potential to effectively reduce unintentional drowning related to these behaviors and could be considered by other municipalities and jurisdictions.

Effects of anthropogenic emissions on aerosol formation from isoprene and monoterpenes in the southeastern United States.

Secondary organic aerosol (SOA) constitutes a substantial fraction of fine particulate matter and has important impacts on climate and human health. The extent to which human activities alter SOA formation from biogenic emissions in the atmosphere is largely undetermined. Here, we present direct observational evidence on the magnitude of anthropogenic influence on biogenic SOA formation based on comprehensive ambient measurements in the southeastern United States (US). Multiple high-time-resolution mass spectrometry organic aerosol measurements were made during different seasons at various locations, including urban and rural sites in the greater Atlanta area and Centreville in rural Alabama. Our results provide a quantitative understanding of the roles of anthropogenic SO2 and NOx in ambient SOA formation. We show that isoprene-derived SOA is directly mediated by the abundance of sulfate, instead of the particle water content and/or particle acidity as suggested by prior laboratory studies. Anthropogenic NOx is shown to enhance nighttime SOA formation via nitrate radical oxidation of monoterpenes, resulting in the formation of condensable organic nitrates. Together, anthropogenic sulfate and NOx can mediate 43-70% of total measured organic aerosol (29-49% of submicron particulate matter, PM1) in the southeastern US during summer. These measurements imply that future reduction in SO2 and NOx emissions can considerably reduce the SOA burden in the southeastern US. Updating current modeling frameworks with these observational constraints will also lead to more accurate treatment of aerosol formation for regions with substantial anthropogenic-biogenic interactions and consequently improve air quality and climate simulations.

Racial/ethnic disparities in revascularization for limb salvage: an analysis of the National Surgical Quality Improvement Program database.

INTRODUCTION: Previous reports have suggested that black patients have a higher rate of major lower extremity amputation and a lower rate of revascularization for limb salvage when compared to white patients. OBJECTIVE: We undertook this study to determine the extent of this ethnic disparity in recent years and to evaluate whether the widespread adoption of endovascular techniques has had an impact on this disparity. METHODS: The American College of Surgeons' National Surgical Quality Improvement Program (NSQIP) database was queried to identify all patients who had undergone an above- or below-knee amputation as well as all patients who had undergone an open or endovascular revascularization procedure for critical limb ischemia for the years 2005 to 2006. Patient demographics and 30-day outcomes were recorded, and comparisons were made among the different ethnic groups. RESULTS: There were 1568 patients identified in the NSQIP database as having undergone a major lower extremity amputation in 2005 and 2006. Of these patients, 54% were white, 29% black, 8% Hispanic, and 0.7% Asian. Eight percent of patients did not have identifying ethnic data. The group undergoing amputation was primarily male (61%) with a mean age of 65. Median length of stay was 11 days, and 30-day mortality was 9% following amputation. During this same time period, 4191 patients underwent an open surgical procedure and 569 patients underwent an endovascular procedure for the purposes of limb salvage. Of those patients undergoing an open procedure, 74% were white, 12% black, 4% Hispanic, 0.4% Asian, and 10% did not have identifying ethnic data. Open surgical patients were primarily male (63%) with a mean age of 66. Median length of stay was 6 days, and 30-day mortality was 3.3%. Of those patients undergoing an endovascular procedure, 79% were white, 10% black, 2% Hispanic, 1% Asian, and 8% did not have identifying ethnic data. The endovascular group was also primarily male (61%) with a mean age of 68. Median length of stay was 5 days, and 30-day mortality was 4%. CONCLUSION: There remains a significant ethnic disparity in limb-salvage revascularization. Blacks comprise 29% of patients undergoing a major lower extremity amputation, but only 12% of those undergoing an open surgical procedure and 10% of those undergoing an endovascular procedure for limb salvage. The widespread adoption of endovascular revascularization techniques appears not to have had much impact on this disparity.

Inhibition of CaV3.2 T-type calcium channels in peripheral sensory neurons contributes to analgesic properties of epipregnanolone.

RATIONALE: T-type calcium channels (T-channels) play an important role in controlling excitability of nociceptors. We have previously shown that a synthetic series of 5ß-reduced steroids induce a voltage-dependent blockade of T-currents in rat dorsal root ganglia (DRG) cells in vitro and induce potent analgesia to thermal stimuli in rats in vivo (Mol Pharmacol 66:1223-1235, 2004). OBJECTIVES: Here, we investigated the effects of the endogenous 5ß-reduced neuroactive steroid molecule, epipregnanolone [(3ß,5ß)-3-hydroxypregnan-20-one], on peripheral nociception. METHODS: We used acutely dissociated DRG cells in vitro from adult rats as well as in vivo pain studies in mice and rats to investigate the effects of epipregnanolone on DRG T-channels. RESULTS: We found that epipregnanolone reversibly blocked DRG T-currents with a half-maximal inhibitory concentration (IC50) of 2 µM and stabilized the channel in the inactive state. However, sodium, potassium, and gamma-aminobutyric acid (GABA)-gated ionic currents were not sensitive to the blocking effects of epipregnanolone even at 10 µM. In ensuing in vivo studies, we found that intraplantar (i.pl.) injections of epipregnanolone directly into peripheral receptive fields reduced responses to nociceptive heat stimuli in rats in a dose-dependent fashion. Furthermore, i.pl. epipregnanolone injections effectively reduced responses to peripheral nociceptive thermal and mechanical stimuli in wild-type mice but had no effect on the responses of CaV3.2 knockout mice. CONCLUSIONS: We conclude that the inhibition of peripheral CaV3.2 T-channels contributes to the potent analgesic effect of the endogenous steroid epipregnanolone.

3-step approach towards evaluation and elimination of acid use in pre-treatment for a brackish water reverse osmosis process.

To control carbonate scale formation on reverse osmosis (RO) membrane surfaces, it is common practice to add acid as a pre-treatment chemical. However, advancements in the formulation of proprietary scale inhibitors have resulted in a re-evaluation of the need to suppress the pH of RO feedwater. In this study, a 3-step approach was taken to eliminate sulfuric acid pre-treatment at a 4.5 MGD (17,000 m(3)/day) brackish water RO plant operating for over 7 years without previous membrane replacement. The 3-Step approach adopted in this study to evaluate and eliminate use of acid in pre-treatment process involved first pilot testing the plan to reduce the dependence on acid. Secondly, implementing the plan on the full-scale system with conservative pH increments and thirdly continuously screening for scale formation potential using a "canary" monitoring device. This 3-step approach resulted in the successful elimination of sulfuric acid pre-treatment at the brackish water RO plant, with an estimated $105,000 minimum annual cost savings.