Superficial abdominal reflex in syringomyelia: Associations with Chiari I malformation.

An abnormal or absent superficial abdominal reflex (SAR) may be associated with an underlying spinal cord syrinx. The sensitivity of an abnormal or absent SAR and the relationship to Chiari malformation type I (CM-I) or syrinx morphology has not been studied. We aimed to describe the relationship between SAR abnormalities and syrinx size, location, and etiology. Children who underwent brain or c-spine MRI over 11 years were reviewed in this retrospective cohort study. Patients with idiopathic and CM-I-associated syringes (axial diameter ≥ 3 mm) were included. Clinical examination findings (including SAR) and imaging characteristics were analyzed. Of 271 patients with spinal cord syrinx, 200 had either CM-I-associated or idiopathic syrinx, and 128 of these patients had SAR-evaluation documentation. Forty-eight percent (62/128) had an abnormal or absent reflex. Abnormal/absent SAR was more common in patients with CM-I-associated syrinx (61%) compared with idiopathic syrinx (22%) (P < 0.0001). Abnormal/absent SAR was associated with wider syringes (P < 0.001), longer syringes (P < 0.05), and a more cranial location of the syrinx (P < 0.0001). Controlling for CM-I, scoliosis, age, sex, cranial extent of syrinx, and syrinx dimensions, CM-I was independently associated with abnormal or absent SAR (OR 4.2, 95% CI 1.4-14, P < 0.01). Finally, the sensitivity of SAR for identifying a patient with syrinx was 48.1%. An abnormal/absent SAR was present in most patients with CM-I-associated syrinx but in a minority of patients with idiopathic syrinx. This has implications for pathophysiology of CM-I-associated syrinx and in guiding clinical care of patients presenting with syrinx.

Repeat procedures and prescription opioid use after lumbar medial branch nerve radiofrequency ablation in commercially insured patients.

PURPOSE: Although the effectiveness of medial branch nerve radiofrequency ablation (RFA) for lumbosacral facet pain has been described, little is known regarding patterns of repeat RFA utilization and prescription opioid use afterward. DESIGN: Retrospective cohort analysis. PATIENT SAMPLE: Patients undergoing lumbosacral RFA in MarketScan from 2007 to 2016. METHODS: The time until and number of staged RFAs (<180 days after initial RFA) and repeat RFAs (≥180 days after initial RFA), as well as opioid use at 90 and 180 days after RFA were assessed. Survival analyses were employed to estimate subsequent RFA rates, whereas subsequent RFA frequencies were estimated with inverse probability weighting. Repeated measures testing was performed comparing opioid use pre- and post-RFA. RESULTS: Initial RFAs were identified in 44,936 patients. Staged RFAs were performed in 33.1% of patients. Repeat RFAs through 1, 3, and 7 years were performed for 14.6%, 33.5%, and 45.7% of patients, respectively. Within 3 years, 12.2% of patients underwent one repeat RFA, whereas 13.2% of patients underwent two or more. Post-RFA opioid use was examined in 128,310 patients, 32.2% of whom used opioids pre-RFA. By 180 days post-RFA, 8.1% of patients discontinued opioids and 6.7% started opioids (p<.001). Exclusively examining pre-RFA opioid users, 24.9% stopped filling opioid prescriptions 180 days after RFA. CONCLUSIONS: This study delineates utilization rates of repeat RFA in the commerciall y insured population, with one-third undergoing repeat RFA within 3 years. Additionally, the present data indicate that lumbosacral RFA is associated with reduced filling of opioid prescriptions through 180 days.

Syringomyelia in children with closed spinal dysraphism: long-term outcomes after surgical intervention.

OBJECTIVE: The nature of the relationship between spinal cord syrinx and tethered cord is not well known. It is unclear if surgical cord untethering results in resolution or improvement of an associated syrinx. The objective of this study was to report the response of spinal cord syrinx to surgical cord untethering. METHODS: The authors retrospectively reviewed all patients with a syrinx and tethered cord who presented to a single institution over an 11-year interval. Patients with open neural tube defects were excluded. Thirty-one patients were identified, 25 of whom had both clinical and imaging follow-up after surgery. Patients were grouped according to etiology of the tethered cord. Clinical outcomes and syrinx characteristics were recorded. RESULTS: Of the 25 patients with tethered cord, 68% (n = 17) were male. The average age at presentation was 2.5 years (0-10.1 years) and age at surgery was 3.7 years (range 1 day to 17 years). Etiologies of tethered cord were lipomyelomeningocele (n = 8), thickened/fatty filum (n = 7), intradural lipoma (n = 5), myelocystocele (n = 2), meningocele (n = 2), and diastematomyelia (n = 1). Twenty-three of the patients underwent primary untethering, whereas 2 patients had received untethering previously at another institution. The average syrinx length and width prior to surgery were 4.81 vertebral levels (SD 4.35) and 5.19 mm (SD 2.55 mm), respectively. Conus level ranged from L1 to S3. Patients were followed for an average of 8.4 years (1.35-15.85 years). Overall there was no significant change in syrinx length or width postoperatively; the average syrinx length increased by 0.86 vertebral levels (SD 4.36) and width decreased by 0.72 mm (SD 2.94 mm). Seven of 25 patients had improvement in at least one presenting symptom, including scoliosis, weakness, bowel/bladder dysfunction, and pain. Eight patients had stable presenting symptoms. Six patients were asymptomatic and 5 patients had new or worsening symptoms, which included scoliosis, pain, or sensory changes. CONCLUSIONS: Although some syrinxes improved after surgery for tethered cord, radiological improvement was not consistent and did not appear to be associated with change in clinical symptoms. The decision to surgically untether a cord should be focused on the clinical symptoms and not the presence of a syrinx alone. Further studies are needed to confirm this finding.

Beta-blocker Use is Associated with a Reduction in Opioid Use 30 Days After Total Knee Arthroplasty.

BACKGROUND: Total knee arthroplasty (TKA) can lead to chronic pain and prolonged postoperative opioid use. There are few evidence-based interventions to prevent these outcomes. Recently, beta-blockers have emerged as possible novel analgesics. OBJECTIVES: The objective of this study was to determine whether perioperative beta-blocker use is associated with reduced prolonged postoperative opioid use after TKA. STUDY DESIGN: This study used a retrospective cohort design. SETTING: The research took place within Department of Veterans Affairs hospitals in the United States between April 2012 and April 2016. METHODS: Patients: IRB approval was obtained to examine the records of Veterans Affairs (VA) patients undergoing TKA. Patients using opioids 60 days before surgery were excluded. INTERVENTION: The intervention being investigated was perioperative beta-blocker use, overall and by class. MEASUREMENT: Oral morphine equivalent usage through postoperative day 1 and prescription opioid refills through 30, 90, and 365 days after TKA were recorded. Adjusted models were created controlling for relevant demographic and comorbidity covariates. A secondary analysis examined the same outcomes separated by beta-blocker class. RESULTS: The cohort was 93.8% male with a mean age of 66 years. Among the 11,614 TKAs that comprised the cohort, 2,604 (22.4%) were performed on patients using beta-blockers. After adjustment, beta-blocker use was associated with reduced opioid use through 30 days after surgery (odds ratio [OR] 0.89 [95% confidence interval (CI), 0.80-0.99], P = .026). Selective beta-blockers were associated with reduced opioid use at 30 days (OR 0.88 [95% CI, 0.78-0.98], P = .021), and nonselective beta-blockers were associated with reduced oral morphine equivalent usage through postoperative day 1 (beta = -17.9 [95% CI, -29.9 to -5.8], P = .004). LIMITATIONS: Generalizability of these findings is uncertain, because this study was performed on a cohort of predominantly white, male VA patients. This study also measured opioid use, but opioid use is not a perfect surrogate for pain. Nevertheless, opioid use offers value as an objective measure of pain persistence in a national cohort for which patient-reported outcomes are otherwise unavailable. CONCLUSIONS: Perioperative beta-blocker use was associated with reduced prescription opioid use at 30 days after surgery. Both selective and nonselective beta-blockers were associated with reduced opioid use when analyzed individually. KEY WORDS: Analgesics, opioid, arthroplasty, replacement, knee, adrenergic beta-antagonists, pain management.

Trends in lumbar radiofrequency ablation utilization from 2007 to 2016.

BACKGROUND CONTEXT: Lumbar radiofrequency ablation (RFA) is an intervention used to treat facet-mediated chronic low back pain. In some studies with methods consistent with clinical practice guidelines, RFA results in improvements in pain and functional limitations. However, in other studies, RFA demonstrates limited benefit. Despite unanswered questions regarding efficacy of RFA, its use is widespread. PURPOSE: To describe trends in the utilization and cost of lumbar RFA and lumbar facet injections. STUDY DESIGN/SETTING: Retrospective cohort study. PATIENT SAMPLE: The sample was derived from the IBM/Watson MarketScan Commercial Claims and Encounters Databases from 2007 to 2016. OUTCOME MEASURES: Longitudinal trends in the distribution and quantity of lumbar facet injections before lumbar RFA, corticosteroid administration during lumbar facet injections, progression to lumbar RFA after lumbar facet injections, lumbar RFA utilization, and costs of these interventions. METHODS: Two primary cohorts were identified from patients who received lumbar RFA or lumbar facet injection procedures. Utilization rates per 100,000 enrollees were determined for both cohorts. The mean, median, and interquartile ranges of the number of facets targeted and costs per procedure were calculated by year and laterality, as well as overall. Costs in 2018 dollars were estimated by summing gross payment totals from patients and insurance plans. This study was supported by funds from the NIH, and has no conflict of interest associated biases. RESULTS: From 2007 to 2016, lumbar RFA sessions performed per 100,000 enrollees per year increased from 49 to 113, a 130.6% overall increase (9.7% annually). Lumbar facet injection use increased from 201 to 251 sessions per 100,000 enrollees, a 24.9% overall increase (2.5% annually). In the year after a lumbar facet injection, 26.7% of patients received lumbar RFA; 28.6% received another injection but not RFA; and 44.7% received neither. The number of patients receiving two lumbar facet injection procedures prior to lumbar RFA grew from 51.1% in 2010 to 58.8% in 2016. For lumbar RFA, the cost per 100,000 enrollees went from $94,570 in 2007 to $266,680 in 2016, a 12.2% annual increase. For lumbar facet injections, the cost per 100,000 enrollees went from $257,280 in 2007 to $396,580 in 2016, a 4.9% annual increase. CONCLUSIONS: This analysis showed consistent growth in both the frequency and procedure cost of lumbar RFA and facet injections among a large, national, commercially insured population from 2007 to 2016.

A Risk Calculator Using Preoperative Opioids for Prediction of Total Knee Revision Arthroplasty.

OBJECTIVES: Total knee arthroplasty (TKA) is a procedure to improve quality of life. However, some patients require early total knee revision (TKR). Chronic opioid use before TKA is associated with TKR. No risk calculator including opioid use or other risk factors is currently available for predicting TKR. MATERIALS AND METHODS: We retrospectively analyzed medical records of Veterans Affairs patients who underwent TKA from January 1, 2006 to January 1, 2012. Patients were followed until January 1, 2013. Chronic opioid use was defined as opioid use for ≥3 months preoperatively. A cross-validated Cox proportional hazards model was created to predict TKR before initial TKA. Model performance was evaluated by the mean absolute error at 1 and 5 years. RESULTS: Totally, 32,297 patients were included. A risk calculator was generated with a mean absolute error of 0.1% at 1 year and 3.6% at 5 years. Chronic opioid use was a significant predictor of TKR (hazard ratio [HR], 1.27; 95% confidence interval, 1.13-1.43; P<0.001). Other model variables were age (HR, 0.95; P<0.001), female sex (HR, 0.77; P=0.020), body mass index (HR, 0.99; P=0.022), diabetes (HR, 1.20; P=0.001), chronic kidney disease (HR, 1.48; P<0.001), and nonchronic opioid use (HR, 1.07; P=0.313). DISCUSSION: Preoperative chronic opioid use is a predictor of TKR. Using this association and others, a TKA revision risk calculator was generated at http://www.bit.do/tka.

Promoting a Restrictive Intraoperative Transfusion Strategy: The Influence of a Transfusion Guideline and a Novel Software Tool.

BACKGROUND: The effect of neither transfusion guidelines nor decision support tools on intraoperative transfusion has been previously evaluated. The University of Michigan introduced a transfusion guideline in 2009, and in 2011, the Department of Anesthesiology developed a transfusion decision support tool. The primary aim of this study was to assess the associations of the transfusion guideline and the optional use of the software transfusion tool with intraoperative behaviors; pretransfusion hematocrit assessment (whether or not a hematocrit was checked before each red cell unit) and restrictive red cell use (withholding transfusion unless the hematocrit was ≤21%). METHODS: This was a before-after retrospective study without a concurrent control group of patients transfused 1-3 units of red cells intraoperatively. Three phases were studied to provide data both before and after the implementation of the transfusion guideline and the intraoperative software tool. Within each phase, trends of checking hematocrits before transfusion and restrictive transfusion were charted against time. F tests were used to measure differences of slopes. The difference between means of each phase was measured using Mann-Whitney U tests. Independent associations were measured using mixed-effects multivariable logistic regression. A secondary outcome analysis was conducted for 30-day mortality, myocardial infarction, renal injury, and their combination. RESULTS: The transfusion guideline was associated with increased pretransfusion hematocrit evaluation (67.4%, standard deviation [SD] 3.9 vs 76.5%, SD 2.7; P < .001) and restrictive transfusion practice (14.0%, SD 7.4 vs 33.3%, SD 4.4; P = .001). After adjustment for confounders, the guideline phase was independently associated with increased hematocrit checking (odds ratio, 1.72; 95% confidence interval, 1.46-2.03; P < .001) and restrictive red cell transfusion (odds ratio, 2.95; 95% confidence interval, 2.46-3.54; P < .001). The software tool was not associated with either transfusion behavior. There was no significant change in the rate of renal injury (16.06%), myocardial injury (4.93%), 30-day mortality (5.47%), or a composite (21.90%). CONCLUSIONS: The introduction of a transfusion guideline was independently associated with increased intraoperative pretransfusion hematocrit assessment and restrictive transfusion. The use of a software tool did not further influence either behavior.

Influence of smoking on aneurysm recurrence after endovascular treatment of cerebrovascular aneurysms.

OBJECTIVE Smoking is a known risk factor for aneurysm development and aneurysmal subarachnoid hemorrhage, as well as subsequent vasospasm in both untreated individuals and patients who have undergone surgical clipping of cerebrovascular aneurysms. However, there is a lack of data in the current scientific literature about the long-term effects that smoking has on the integrity of endovascular repairs of cerebral aneurysms. This study was designed to determine if any smoking history increased the risk of poorer outcomes and/or aneurysm recurrence in patients who have had endovascular repair of cerebral aneurysms. METHODS The authors retrospectively analyzed the medical records of patients admitted to the University of Michigan Health System from January 1999 to December 2011 with coiled aneurysms and angiography, CT angiography, or MR angiography follow-up. Patients were identified and organized based on many criteria including age, sex, smoking history, aneurysm recurrence, aneurysm location, and Hunt and Hess grade. Analysis was targeted to the patient population with a history of smoking. Bivariate chi-square tests were used to analyze the association between a positive smoking history and documented aneurysm recurrence and were adjusted for potential confounders by fitting multivariate logistic regression models of recurrence. RESULTS A total of 247 patients who had undergone endovascular treatment of 296 documented cerebral aneurysms were included in this study. The recurrence rate among all patients treated with endovascular repair was 24.3%, and the average time to the most recent follow-up imaging studies was 1.62 years. Smokers accounted for 232 aneurysms and were followed up for an average of 1.57 years, with a recurrence rate of 26.3%. Never smokers accounted for the remaining 64 aneurysms and were followed up for an average of 1.82 years, with a recurrence rate of 17.2%. Multivariate analysis revealed that, after controlling for potential confounders, a history of smoking-whether current or former-was associated with a significantly increased risk of aneurysm recurrence. The odds ratios for aneurysm recurrence for current and former smokers were 2.739 (95% CI 1.127-7.095, p = 0.0308) and 2.698 (95% CI 1.078-7.212, p = 0.0395), respectively, compared with never smokers. CONCLUSIONS A positive smoking history is associated with a significantly increased risk of aneurysm recurrence in patients who have undergone endovascular repair of a cerebral aneurysm, compared with the risk in patients who have never smoked.

Labetalol Use Is Associated With Increased In-Hospital Infection Compared With Nicardipine Use in Intracerebral Hemorrhage.

BACKGROUND AND PURPOSE: Increased sympathetic tone causes hypertension after intracerebral hemorrhage, and blood pressure reduction has been studied as a way to decrease hemorrhage growth and improve outcomes. It is unknown if the antihypertensive used to achieve blood pressure goals influences either. Because sympatholytic drugs reduce death and infection in animal models, we hypothesized that labetalol would improve outcomes compared with nicardipine. METHODS: Prospective data from a single center were retrospectively reviewed. Patients receiving labetalol, nicardipine, or both during their first 3 days of hospitalization were included. Outcomes included in-hospital death; discharge modified Rankin Score >2; and in-hospital urinary tract infection, pneumonia, or bacteremia. Patients were compared with propensity scoring and analyzed with linear models adjusted for significant confounders. RESULTS: Of 1066 admissions, 525 were treated with labetalol or nicardipine and are included; 229 (43.6%) received labetalol, 107 (20.4%) received nicardipine, and 189 (36.0%) received both. Mortality and infection rates were 40.2% and 15.8%, respectively, 77.2% had a modified Rankin Score >2. After adjustment, compared with nicardipine alone, labetalol alone was associated with infection (odds ratio, 3.12; confidence interval, 1.27-7.64; P=0.013) but not when combined with nicardipine (odds ratio, 2.44; confidence interval, 0.98-6.07; P=0.055). Labetalol, with or without nicardipine, was not associated with death or discharge modified Rankin Score >2. CONCLUSIONS: Compared with nicardipine, labetalol was associated with increased in-hospital infections, but not mortality or modified Rankin Score >2. These findings do not support our hypothesis that labetalol use improves outcomes relative to nicardipine in intracerebral hemorrhage.

Increased infections with ß-blocker use in ischemic stroke, a ß2-receptor mediated process?

Strokes promote immunosuppression, partially from increased sympathetic activity. Altering sympathetic drive with ß-blockers has variably been shown to improve stroke outcomes. This study adds to this literature using propensity score matching to limit confounding and by examining the effects of selective and non-selective ß-blockers. Prospective data from acute ischemic stroke admissions at a single center from July 2010-June 2015 were analyzed. Outcomes included infection (urinary tract infection [UTI], pneumonia, or bacteremia), discharge modified Rankin Score (mRS), and in-hospital death. Any selective and non-selective ß-blocker use during the first 3 days of admission were investigated with propensity score matching. A sensitivity analysis was also performed. This study included 1431 admissions. Any ß-blocker use was associated with increased infections (16.4 vs. 10.7%, p = 0.030). Non-selective ß-blocker use was associated with increased infections (18.9 vs. 9.7%, p = 0.005) and UTIs (13.0 vs. 5.5%, p = 0.009). Selective ß-blocker use was not associated with infection. There were no associations between ß-blocker use and in-hospital death or discharge mRS. In the sensitivity analysis, the association between non-selective ß-blocker use and urinary tract infections persisted (12.5 vs. 4.2%, p = 0.044). No associations with death or mRS were found. Early ß-blocker use after ischemic stroke may increase the risk of infection but did not change disability or mortality risk. The mechanism may be mediated by ß2-adrenergic receptor antagonism given the different effects seen with selective versus non-selective ß-blocker use.

Weekend Discharge and Stroke Quality of Care: Get With The Guidelines-Stroke Data from a Comprehensive Stroke Center.

OBJECTIVE: Get With The Guidelines-Stroke collects data on hospital compliance with evidence-based stroke quality of care indicators. Prior work has investigated a link between weekend hospital admission and increased mortality after stroke. There is, however, a paucity of work investigating a similar association between weekend hospital discharge and quality of care. We aimed to determine if weekend discharge affects care to enlighten opportunities for quality improvement. MATERIALS AND METHODS: Through a retrospective analysis of records from a Comprehensive Stroke Center from July 2010 to June 2015, we identified patients with ischemic stroke, subarachnoid hemorrhage, and intracerebral hemorrhage. Our quality of care indicators were dysphagia screening, rehabilitation assessment, smoking cessation counseling, stroke education, and weight reduction counseling. We created regression models to find adjusted differences in quality of care measure compliance for patients discharged on the weekend. RESULTS: Our analysis included 2737 patients, of which 431 were discharged on the weekend. After adjustment, weekend discharge was significantly associated with reduced stroke education (odds ratio .67, confidence interval .51-0.88, P = .004) and reduced weight reduction counseling (odds ratio .65, confidence interval .45-0.93, P = .018). CONCLUSIONS: Hospital discharge on the weekend was associated with an adjusted one-third decrease in odds of stroke education and weight reduction counseling. There is an opportunity for quality improvement in educating stroke patients before hospital discharge on the weekend.

Syrinx location and size according to etiology: identification of Chiari-associated syrinx.

OBJECT Syrinx size and location within the spinal cord may differ based on etiology or associated conditions of the brain and spine. These differences have not been clearly defined. METHODS All patients with a syrinx were identified from 14,118 patients undergoing brain or cervical spine imaging at a single institution over an 11-year interval. Syrinx width, length, and location in the spinal cord were recorded. Patients were grouped according to associated brain and spine conditions including Chiari malformation Type I (CM-I), secondary CM (2°CM), Chiari malformation Type 0 (CM-0), tethered cord, other closed dysraphism, and spinal tumors. Syringes not associated with any known brain or spinal cord condition were considered idiopathic. Syrinx characteristics were compared between groups. RESULTS A total of 271 patients with a syrinx were identified. The most common associated condition was CM-I (occurring in 117 patients [43.2%]), followed by spinal dysraphism (20 [7.4%]), tumor (15 [5.5%]), and tethered cord (13 [4.8%]). Eighty-three patients (30.6%) did not have any associated condition of the brain or spinal cord and their syringes were considered idiopathic. Syringes in patients with CM-I were wide (7.8 ± 3.9 mm) compared with idiopathic syringes (3.9 ± 1.0, p < 0.0001) and those associated with tethered cord (4.2 ± 0.9, p < 0.01). When considering CM-I-associated and idiopathic syringes, the authors found that CM-I-associated syringes were more likely to have their cranial extent in the cervical spine (88%), compared with idiopathic syringes (43%; p < 0.0001). The combination of syrinx width greater than 5 mm and cranial extent in the cervical spine had 99% specificity (95% CI 0.92-0.99) for CM-I-associated syrinx. CONCLUSIONS Syrinx morphology differs according to syrinx etiology. The combination of width greater than 5 mm and cranial extent in the cervical spine is highly specific for CM-I-associated syringes. This may have relevance when determining the clinical significance of syringes in patients with low cerebellar tonsil position.

Improving the care of elderly adults undergoing surgery in Michigan.

OBJECTIVES: To determine whether failure to rescue, as a driver of mortality, can be used to identify which hospitals attenuate the specific risks inherent to elderly adults undergoing surgery. DESIGN: Retrospective cohort study. SETTING: State-wide surgical collaborative in Michigan. PARTICIPANTS: Older adults undergoing major general or vascular surgery between 2006 and 2011 (N = 24,216). MEASUREMENTS: Thirty-four hospitals were ranked according to risk-adjusted 30-day mortality and grouped into tertiles. Within each tertile, rates of major complications and failure to rescue were calculated, stratifying outcomes according to age (<75 vs ≥ 75). Next, differences in failure-to-rescue rates between age groups within each hospital were calculated. RESULTS: Failure-to-rescue rates were more than two times as high in elderly adults as in younger individuals in each tertile of hospital mortality (26.0% vs 10.3% at high-mortality hospitals, P < .001). Within hospitals, the average difference in failure-to-rescue rates was 12.5%. Nine centers performed better than expected, and three performed worse than expected, with the largest differences exceeding 25%. CONCLUSION: Although elderly adults experience higher failure-to-rescue rates, this does not account for hospitals' overall capacity to rescue individuals from complications. Comparing rates of younger and elderly adults within hospitals may identify centers where efforts toward complication rescue favor, or are customized for, elderly adults. These centers should be studied as part of the collaborative's effort to address the disparate outcomes that elderly adults in Michigan experience.

Minimal effect of lipid charge on membrane miscibility phase behavior in three ternary systems.

Giant unilamellar vesicles composed of a ternary mixture of phospholipids and cholesterol exhibit coexisting liquid phases over a range of temperatures and compositions. A significant fraction of lipids in biological membranes are charged. Here, we present phase diagrams of vesicles composed of phosphatidylcholine (PC) lipids, which are zwitterionic; phosphatidylglycerol (PG) lipids, which are anionic; and cholesterol (Chol). Specifically, we use DiPhyPG-DPPC-Chol and DiPhyPC-DPPG-Chol. We show that miscibility in membranes containing charged PG lipids occurs over similarly high temperatures and broad lipid compositions as in corresponding membranes containing only uncharged lipids, and that the presence of salt has a minimal effect. We verified our results in two ways. First, we used mass spectrometry to ensure that charged PC/PG/Chol vesicles formed by gentle hydration have the same composition as the lipid stocks from which they are made. Second, we repeated the experiments by substituting phosphatidylserine for PG as the charged lipid and observed similar phenomena. Our results consistently support the view that monovalent charged lipids have only a minimal effect on lipid miscibility phase behavior in our system.