Failure of diltiazem to prevent 1:1 conduction of atrial flutter: a case report

BACKGROUND

Atrial flutter with 1:1 conduction to the ventricles is a dangerous cardiac arrhythmia. Contemporary guidelines recommend atrioventricular nodal blocking agents should be co-administered with class 1C anti-arrhythmics, as prophylaxis against 1:1 flutter. No guidance is provided on the type or strength of atrioventricular nodal blockade required, and in practice, these agents are frequently prescribed at low dose, or even omitted, due to their side effect profile.

CASE PRESENTATION

A 62 year old Caucasian man with a history of paroxysmal atrial fibrillation treated with flecainide, presented with atrial flutter with 1:1 conduction to the ventricles and was cardioverted. Diltiazem was added to prevent this complication and he again presented with atrial flutter with 1:1 conduction to the ventricles, despite prophylaxis with coadministration of diltiazem.

CONCLUSIONS

This case report demonstrates failure of diltiazem to prevent 1:1 flutter in a patient chronically treated with flecainide for paroxysmal atrial fibrillation.

Laccase-based biocathodes: Comparison of chitosan and Nafion

Chitosan and Nafion(®) are both reported as interesting polymers to be integrated into the structure of 3D electrodes for biofuel cells. Their advantage is mainly related to their chemical properties, which have a positive impact on the stability of electrodes such as the laccase-based biocathode. For optimal function in implantable applications the biocathode requires coating with a biocompatible semi-permeable membrane that is designed to prevent the loss of enzyme activity and to protect the structure of the biocathode. Since such membranes are integrated into the electrodes ultimately implanted, they must be fully characterized to demonstrate that there is no interference with the performance of the electrode. In the present study, we demonstrate that chitosan provides superior stability compared with Nafion(®) and should be considered as an optimum solution to enhance the biocompatibility and the stability of 3D bioelectrodes.

Health outcomes associated with polypharmacy in community-dwelling older adults: a systematic review

OBJECTIVES

To summarize evidence regarding the health outcomes associated with polypharmacy, defined as number of prescribed medications, in older community-dwelling persons.

DESIGN

Systematic review of MEDLINE (OvidSP 1946 to May, Week 3, 2014).

SETTING

Community.

PARTICIPANTS

Observational studies examining health outcomes according to number of prescription medications taken.

MEASUREMENTS

Association between number of medications and health outcomes. Because of the importance of comorbidity as a potential confounder of the relationship between polypharmacy and health outcomes, articles were assessed regarding the quality of their adjustment for confounding.

RESULTS

Of the 50 studies identified, the majority that were rated good in terms of their adjustment for comorbidity demonstrated relationships between polypharmacy and a range of outcomes, including falls, fall outcomes, fall risk factors, adverse drug events, hospitalization, mortality, and measures of function and cognition. However, a number of these studies failed to demonstrate associations, as did a substantial proportion of studies rated fair or poor.

CONCLUSION

Data are mixed regarding the relationship between polypharmacy, considered in terms of number of medications, and adverse outcomes in community-dwelling older persons. Because of the challenge of confounding, randomized controlled trials of medication discontinuation may provide more-definitive evidence regarding this relationship than observational studies can provide.

Frailty, cognitive impairment, and functional disability in older women with female pelvic floor dysfunction

INTRODUCTION AND HYPOTHESIS

There is a growing body of evidence demonstrating frailty as an important predictor of surgical outcomes in older adults undergoing major surgeries. The age-related onset of many symptoms of female pelvic floor dysfunction (PFD) in women suggests that many women seeking treatment for PFD may also have a high prevalence of frailty, which could potentially impact the risks and benefits of surgical treatment options. Our primary objective was to determine the prevalence of frailty, cognitive impairment, and functional disability in older women seeking treatment for PFD.

METHODS

We conducted a cross-sectional study with prospective recruitment between September 2011 and September 2012. Women, age 65 years and older, were recruited at the conclusion of their new patient consultation for PFD at a tertiary center. A comprehensive geriatric screening including frailty measurements (Fried Frailty Index), cognitive screening (Saint Louis University Mental Status score), and functional status evaluation for activities of daily living (Katz ADL score) was conducted.

RESULTS

Sixteen percent (n/N = 25/150) of women were categorized as frail according to the Fried Frailty Index score. After adjusting for education level, 21.3 % of women (n/N = 32/150) screened positive for dementia and 46 (30.7 %) reported functional difficulty or dependence in performing at least one Katz ADL. Sixty-nine women (46.0 %) chose surgical options for treatment of their PFD at the conclusion of their new patient visit with their physician.

CONCLUSIONS

Frailty, cognitive impairment, and functional disability are common in older women seeking treatment for PFD.

The effects of comorbidity on the benefits and harms of treatment for chronic disease: a systematic review

Background

There are concerns about the potential for unintentional harms when clinical practice guidelines are applied to patients with multimorbidity. The objective was to summarize the evidence regarding the effect(s) of comorbidity on the outcomes of medication for an index chronic condition.

Methods

A systematic review was conducted of studies published in MEDLINE and Cochrane Trials before May 2012. The search strategy was constructed to identify articles indexed with “comorbidity” or a related term or by a given condition and one or more additional specified comorbid conditions. The search yielded 3252 articles, of which 37 passed the title/abstract screening process, and 22 were included after full-text review. An additional 23 articles were identified by screening the reference lists for included articles. Information was extracted on study design; population; therapy; comparison groups; outcome(s); main findings.

Findings

Indexing of articles was inconsistent, with no term for “multimorbidity,” and rare use of “comorbidity”. Only one article examined the effects of comorbidity per se, finding no benefit of tight control of DM among persons with high comorbidity, defined using a comorbidity index. The remainder examined pairs of conditions, the majority of which were post-hoc analyses of randomized controlled trials and which found no difference in outcomes according to whether a comorbid condition was present. Several demonstrated no difference or an increased risk of adverse outcome among persons with DM and tight control of HTN as compared to usual control. Several demonstrated lack of benefit of statins among persons with end-stage renal disease.

Conclusions

There is limited evidence regarding the effects of multiple comorbidities on treatment outcomes. The majority of studies demonstrated no effect of a single comorbid condition on outcomes. Additional studies examining a broad range of comorbidity are required, along with clear and consistent indexing to allow for improved synthesis of the evidence.

Childbirth expectations and sources of information among low- and moderate-income nulliparous pregnant women

This article explores the childbirth expectations and sources of information of first-time mothers using a qualitative descriptive method. A purposive sample of low- to moderate-income nulliparous women (N = 7) from an urban area in Connecticut were interviewed in their third trimester of pregnancy. The themes that emerged touched on mode of birth, supportive resources, emotional and physical expectations, control, and health of the baby. No one participated in childbirth education classes, and instead cited mostly informal sources of information such as family, friends, the Internet, and television. In light of advanced technology and increased access to on-demand information, the results of this study should remind health-care providers to discuss childbirth expectations and the sources of information with patients.

Surgical site infection after hysterectomy

OBJECTIVE

Our objective was to estimate the occurrence of surgical site infections (SSI) after hysterectomy and the associated risk factors.

STUDY DESIGN

We conducted a cross-sectional analysis of the 2005-2009 American College of Surgeons National Surgical Quality Improvement Program participant use data files to analyze hysterectomies. Different routes of hysterectomy were compared. The primary outcome was to identify the occurrence of 30-day superficial SSI (cellulitis) after hysterectomy. Secondary outcomes were the occurrence of deep and organ-space SSI after hysterectomy. Logistic regression models were conducted to further explore the associations of risks factors with SSI after hysterectomy.

RESULTS

A total of 13,822 women were included in our final analysis. The occurrence of postoperative cellulitis after hysterectomy was 1.6% (n = 221 women). Risk factors that were associated with cellulitis were route of hysterectomy with an adjusted odds ratio (AOR) of 3.74 (95% confidence interval [CI], 2.26-6.22) for laparotomy compared with the vaginal approach, operative time >75th percentile (AOR, 1.84; 95% CI, 1.40-2.44), American Society of Anesthesia class ≥ 3 (AOR, 1.79; 95% CI, 1.31-2.43), body mass index ≥40 kg/m(2) (AOR, 2.65; 95% CI, 1.85-3.80), and diabetes mellitus (AOR, 1.54; 95% CI, 1.06-2.24) The occurrence of deep and organ-space SSI was 1.1% (n = 154 women) after hysterectomy.

CONCLUSION

Our finding of the decreased occurrence of superficial SSI after the vaginal approach for hysterectomy reaffirms the role for vaginal hysterectomy as the route of choice for hysterectomy.

Cost-effectiveness of endometrial evaluation prior to morcellation in surgical procedures for prolapse

OBJECTIVE

The objective of the study was to compare the cost-effectiveness of 3 screening options for endometrial cancer in asymptomatic, postmenopausal women prior to undergoing morcellation in minimally invasive supracervical hysterectomy and minimally invasive sacral colpopexy for the treatment of pelvic organ prolapse.

STUDY DESIGN

A decision tree model was constructed to compare no screening, endometrial biopsy, and transvaginal ultrasound for asymptomatic, postmenopausal women prior to surgery. Effectiveness was measured by life-years. The incremental cost-effectiveness ratio, defined as the difference in cost between 2 screening options divided by the difference in life-years between the 2 options, was calculated in 2012 US dollars for endometrial biopsy and transvaginal ultrasound, in comparison with no screening.

RESULTS

Using an endometrial cancer prevalence of 0.6% and a 40% risk of upstaging after morcellation, the expected per-patient cost was $8800, $9023, and $9112 over 5 years for no screening, endometrial biopsy, and transvaginal ultrasound, respectively. The expected life-years saved compared with no screening were 0.00108 for endometrial biopsy and 0.00105 for transvaginal ultrasound, ie, 0.39 and 0.38 days, respectively. The estimated incremental cost-effectiveness ratio was $207,348 for endometrial biopsy and $298,038 for transvaginal ultrasound compared with no screening. A sensitivity analysis showed that the prevalence of endometrial cancer and the risk of endometrial cancer upstaging after morcellation had the greatest impact on the cost-effectiveness of screening.

CONCLUSION

For asymptomatic, postmenopausal women, preoperative endometrial evaluation via endometrial biopsy or transvaginal ultrasound helps improve the preoperative detection of endometrial cancer, but universal screening is not cost effective.

The association between urinary and fecal incontinence and social isolation in older women

OBJECTIVE

To describe the association between social isolation and urinary incontinence and fecal incontinence in older women.

METHODS

We conducted a secondary database analysis of the National Social Life, Health and Aging Project for women aged 57 to 85 years old. Our primary outcome was self-report of often feeling isolated. We explored self-report of daily urinary incontinence and weekly fecal incontinence. Two logistic regression analyses were performed to assess the association between often feeling isolated and (1) daily urinary incontinence and (2) weekly fecal incontinence.

RESULTS

A total of 1412 women were included in our analysis. Daily urinary incontinence was reported by 12.5% (177/1412) of community-dwelling older women. More women with daily urinary incontinence reported often feeling isolated (6.6%; 95% confidence interval [CI], 1.3-11.9 vs 2.6%; 95% CI, 1.7-3.5; P = .04) compared with women without daily urinary incontinence. Women with daily urinary incontinence had 3.0 (95% CI, 1.1-7.6) increased odds of often feeling isolated after adjusting for depressive symptoms, age, race, education, and overall health. Weekly fecal incontinence was reported by 2.9% (41/1412) of women. Weekly fecal incontinence and often feeling isolated were associated on univariable analysis (crude odds ratio, 4.6; 95% CI, 1.4-15.1). However, after adjusting for depressive symptoms, age, race, education, and overall health the association between weekly fecal incontinence and often feeling isolated was not significant (adjusted odds ratio, 0.65; 95% CI, 0.1-5.3; P = .65).

CONCLUSION

After adjusting for confounders, daily urinary incontinence was significantly associated with often feeling isolated. Weekly fecal incontinence was not found to be associated with often feeling isolated on multivariable logistic regression.

Sexual function in older women after oophorectomy

OBJECTIVE

To compare the sexual function of older women who had bilateral oophorectomy with that of older women who had retained their ovaries.

METHODS

This cross-sectional study involved analysis of 1,352 women aged 57 to 85 years from the National Social Life, Health, and Aging Project. Women with previous bilateral oophorectomy were compared with women who retained their ovaries. The primary outcome of interest was self-report of sexual ideation, chosen because having thoughts about sexual experiences is not prohibited by either a partner or a woman's own physical limitations.

RESULTS

Three hundred fifty-six (25.8%) women reported previous bilateral oophorectomy. Our analysis achieved 90% power to detect a difference of 10% in sexual ideation. No significant difference in the report of sexual ideation was found between women with previous bilateral oophorectomy and women who retained their ovaries (54.5% and 95% confidence interval [CI] 48.1-61.0 compared with 49.9% and 95% CI 45.3-54.5, P=.230), even after adjusting for current hormone therapy, age, education, and race (adjusted odds ratio 1.32, 95% CI 0.96-1.80).

CONCLUSION

Bilateral oophorectomy may not play a pivotal role in sexual ideation and function among older women.

LEVEL OF EVIDENCE

II.

Spinal anaesthesia for ambulatory arthroscopic surgery of the knee: a comparison of low-dose prilocaine and fentanyl with bupivacaine and fentanyl

BACKGROUND

Prospective data on the use of prilocaine for ambulatory spinal anaesthesia remain limited. We compared the behaviour and characteristics of subarachnoid block using prilocaine and fentanyl with that of bupivacaine and fentanyl.

METHODS

In a prospective, double-blind, randomized controlled trial, 50 patients undergoing elective ambulatory arthroscopic knee surgery received subarachnoid anaesthesia, with either prilocaine 20 mg and fentanyl 20 µg (Group P) or plain bupivacaine 7.5 mg and fentanyl 20 µg (Group B). Primary endpoints included times for onset of maximum sensory block level and regression of sensory block to L4, and also motor block at 1 and 2 h, and levels of haemodynamic stability. Comparisons between the groups were made by χ² test for proportions and the Mann-Whitney test for ordinal data. Time-to-event data were analysed by the Mann-Whitney test for uncensored data or the logrank test for censored data.

RESULTS

At 2 h, motor block in Group P had fully resolved in 86% of patients, compared with 27% in Group B (P<0.001). Median time to regression of sensory block to L4 was significantly shorter in Group P (97 min) than in Group B (280 min) (P<0.001). A clinically significant decrease in arterial pressure was more common in Group B (73%) than in Group P (32%) (P=0.004). Two patients in Group P required conversion to general anaesthesia, but for reasons unrelated to prilocaine itself.

CONCLUSIONS

The combination of prilocaine and fentanyl is a better alternative to that of low-dose bupivacaine and fentanyl, for spinal anaesthesia in ambulatory arthroscopic knee surgery.

Factors affecting the incidence of infection in hip and knee replacement: an analysis of 5277 cases

Infection remains a significant and common complication after joint replacement and there is debate about which contributing factors are important. Few studies have investigated the effect of the operating time on infection. We collected data prospectively from 5277 hip and knee replacements which included the type of procedure, the operating time, the use of drains, the operating theatre, surgeon, age and gender. In a subgroup of 3449 knee replacements further analysis was carried out using the tourniquet time in place of the operating time. These variables were assessed by the use of generalised linear modelling against superficial, deep or joint-space post-operative infection as defined by the Australian Surgical-Site Infection criteria. The overall infection rate was 0.98%. In the replacement data set both male gender (z = 3.097, p = 0.00195) and prolonged operating time (z = 4.325, p < 0.001) were predictive of infection. In the knee subgroup male gender (z = 2.250, p = 0.02447), a longer tourniquet time (z = 2.867, p = 0.00414) and total knee replacement (versus unicompartmental knee replacement) (z = -2.052, p = 0.0420) were predictive of infection. These findings support the view that a prolonged operating time and male gender are associated with an increased incidence of infection. Steps to minimise intra-operative delay should be instigated, and care should be exercised when introducing measures which prolong the duration of joint replacement.

Contractility of retinal pericytes grown on silicone elastomer substrates is through a protein kinase A-mediated intracellular pathway in response to vasoactive peptides

The normal function of retinal capillaries to distribute blood within the retina depends on appropriate contractility of retinal pericytes, which is thought to be modulated by agents that alter intracellular cyclic adenosine-3'-monophosphate (cAMP) levels. We examined the hypothesis that the vasoactive peptides Vasoactive Intestinal Peptide (VIP) and Pituitary Adenylate Cyclase Activating Peptide (PACAP) reduce pericyte contractility via a protein kinase A (PKA)-mediated intracellular pathway that utilises cAMP. We utilised a single-call assay of contractility that is based on visualising the contractile force exerted by the pericytes on a silicone elastomer substrate and quantified, as a contractility index, from the number and length of wrinkles induced in the silicone elastomer by the pericytes. Pericytes were cultured from the retinas of freshly killed abattoir cattle, and identified in culture using immunohistochemical techniques. The pericytes contracted in response to norepinephrine (EC(50)=8 microM) and relaxed in response to both VIP (EC(50)=48 nM) and PACAP (EC(50)=3 nM). The relaxation induced by PACAP was inhibited by Rp-cAMPS (EC(50)=26 microM), which is an agent that inhibits cAMP binding at PKA. We confirmed the activation of PKA by PACAP in experiments where H89 also inhibited the PACAP-induced relaxation. U71322, which inhibits phospholipase C-linked events, was also able to inhibit the PACAP-induced pericyte relaxation. Our results support the hypothesis that PACAP leads to the relaxation of pericytes via a PKA-mediated intracellular pathway and a phospholipase C-mediated pathway, which probably relies on hyperpolarisation because of activation of Ca(2+)-dependent potassium channels. This single-cell assay has proved useful as the basis for the development of a diagnostic procedure for diabetic retinopathy, which is an eye disease caused by abnormal regulation of blood flow in the retinal capillaries.

Intra-articular fibrous band of the ankle: an uncommon cause of post-traumatic ankle pain

A case of an intra-articular fibrous band of the ankle is presented with emphasis on the MR imaging appearances. This entity is an important but uncommon cause of post-traumatic ankle pain and is well recognized within the arthroscopy literature, but there is little if any documentation of this condition in the imaging literature.

Access to intensive care unit beds for neurosurgery patients: a qualitative case study

OBJECTIVES

The purpose of this study was to describe the process used to decide which patients are admitted to the intensive care unit (ICU) at a hospital with special focus on access for neurosurgery patients, and evaluate it using "accountability for reasonableness".

METHODS

Qualitative case study methodology was used. Data were collected from documents, interviews with key informants, and observations. The data were subjected to thematic analysis and evaluated using the four conditions of "accountability for reasonableness" (relevance, publicity, appeals, enforcement) to identify good practices and opportunities for improvement.

RESULTS

ICU admissions were based on the referring physician's assessment of the medical need of the patient for an ICU bed. Non-medical criteria (for example, family wishes) also influenced admission decisions. Although there was an ICU bed allocation policy, patient need always superceded the bed allocation policy. ICU admission guidelines were not used. Admission decisions and reasons were disseminated to the ICU charge nurse, the bed coordinator, the ICU resident, the intensivist, and the requesting physician/surgeon by word of mouth and by written documentation in the patient's chart, but not to the patient or family. Appeals occurred informally, through negotiations between clinicians. Enforcement of relevance, publicity, and appeals was felt to be either non-existent or deficient.

CONCLUSIONS

Conducting a case study of priority setting decisions for patients requiring ICU beds, with a special focus on neurosurgical patients, and applying the ethical framework "accountability for reasonableness" can help critical care units improve the fairness of their priority setting.

Priority-setting decisions for new cancer drugs: a qualitative case study

BACKGROUND

Frameworks for legitimate and fair priority setting emphasise the importance of the rationales for priority setting decisions. However, priority setting rationales, in particular for new cancer drugs, are not well described. We describe the rationales used by a committee making funding decisions for new cancer drugs.

METHODS

We did a qualitative case study of a priority setting committee (Cancer Care Ontario Policy Advisory Committee for the New Drug Funding Program) by analysing documents, interviewing committee members, and observing committee meetings.

FINDINGS

We identified and described decisions and rationales related to 14 drugs in eight disease conditions over 3 years. Our main findings were that: priority setting existed in relation to resource mobilisation; clinical benefit was the primary factor in decisions; in the context of an expanding budget, rationales changed; rationales could change as costs for individual treatments increased; when all options were reasonable, groups funded a range of options and let patients decide; and priority setting rationales involve clusters of factors, not simple trade-offs.

INTERPRETATION

Observing priority-setting decisions and their rationales in actual practice reveals lessons not contained in theoretical accounts.

Comparison of torsional strengths of bioabsorbable screws for anterior cruciate ligament reconstruction

The goals of this study were to evaluate torsional strength and modes of failure in commercially available bioabsorbable interference screws and to test the effect of screw diameter on torsional strength when screws become jammed during insertion. We tested the Arthrex, BioScrew, Endo-Fix, Phantom, and Sysorb screws, all 20 mm in length. Four major modes of failure were encountered. Analysis of variance revealed that both screw type and diameter had a significant effect on failure torque. The Endo-Fix 7-mm screw had the lowest failure torque (1.07 +/- 0.18 N x m) and the Sysorb 8-mm screw had the highest (5.23 +/- 0.24 N x m). The Sysorb was significantly stronger than all the other screws. The failure torques were within the range that has been reported for manual screw insertion. We concluded that technical factors, which can affect insertion torque, assume particular importance with the use of bioabsorbable interference screws.

Priority setting for new technologies in medicine: qualitative case study

OBJECTIVE

To describe priority setting for new technologies in medicine.

DESIGN

Qualitative study using case studies and grounded theory.

SETTING

Two committees advising on priorities for new technologies in cancer and cardiac care in Ontario, Canada.

PARTICIPANTS

The two committees and their 26 members.

MAIN OUTCOME MEASURES

Accounts of priority setting decision making gathered by reviewing documents, interviewing members, and observing meetings.

RESULTS

Six interrelated domains were identified for priority setting for new technologies in medicine: the institutions in which the decision are made, the people who make the decisions, the factors they consider, the reasons for the decisions, the process of decision making, and the appeals mechanism for challenging the decisions.

CONCLUSION

These domains constitute a model of priority setting for new technologies in medicine. The next step will be to harmonise this description of how priority setting decisions are made with ethical accounts of how they should be made.

An entrustment model of consent for surgical treatment of life-threatening illness: perspective of patients requiring esophagectomy

OBJECTIVE

Consent to treatment has been extensively discussed and prescribed from the viewpoint of law, ethics, and policy experts; the viewpoint of patients is less well represented. The purpose of this study was to describe the process of decision making and consent to surgical treatment from the patients' perspective, in the context of life-threatening illness.

METHODS

Face-to-face interviews with 36 patients who had recovered from esophagectomy for cancer at university hospitals in Toronto, Ontario, were analyzed by means of a qualitative analytic approach.

RESULTS

Instead of the accepted model of informed consent and shared decision making, patients identified 6 concepts that describe their experience: (1) cultural belief in surgical cure, (2) enhancement of trust through the referral process, (3) idealization of the specialist surgeon, (4) belief in expertise rather than medical information, (5) resignation to risks of treatment, and (6) acceptance of an expert recommendation as consent to treatment. These concepts were developed into a model of entrustment that unites the narratives of all our patients.

CONCLUSIONS

There is a gap between accepted legal and ethical theories concerning consent and the patients' account of their experiences with surgical treatment of esophageal cancer. Although our findings should not be used to circumvent the ethical and legal requirements of the consent process and are limited to survivors of treatment of life-threatening disease, they support a careful reassessment of informed consent that includes the perspective of patients.

An integrated model of discharge planning for acutely-ill elderly patients

Prior research has demonstrated that current discharge-related practices present resource-related and ethical problems for all those involved. The purpose of this 9-month qualitative study was to develop a more resource efficient and compassionate discharge planning model for acutely-ill, elderly patients. The focus group interviewing method was used to elicit 99 participants' perceptions of an ideal approach to discharge planning. Focus group participants included professionals from acute-care hospitals and community organizations. Telephone interviews were also completed with 25 patients and 6 family members. Themes identified in the analysis revealed that an ideal approach to discharge planning would incorporate seven elements. According to participants, the approach is ideal because it potentially addresses both resource utilization and ethical issues. Program evaluation of the model is underway in order to determine its effectiveness.

Sensitive and selective gas chromatographic methods for the quantitation of camphor, menthol and methyl salicylate from human plasma

Analytical methods using gas chromatography-flame ionization detection (GC-FID) for the quantitation of camphor and menthol and GC-MS for the quantitation of methyl salicylate have been developed for measurement of low concentrations from human plasma. Anethole serves as the internal standard for camphor and menthol and ethyl salicylate serves as the internal standard for methyl salicylate. Plasma samples undergo multiple, sequential extractions with hexane in order to provide optimal recovery. For menthol and camphor, the extracting solvent is reduced in volume and directly injected onto a capillary column (Simplicity-WAX). Extracted methyl salicylate is derivatized with BSTFA prior to injection onto a capillary column (Simplicity-5). Between-day variation (% RSD) at 5 ng/ml varies from 6.2% for methyl salicylate to 13.5% for camphor. The limit of detection for each analyte is 1 ng/ml and the limit of quantitation is 5 ng/ml. These analytical methods have been used in a clinical study to assess exposure from dermally applied patches containing the three compounds.

The Regenstrief Medical Record System: a quarter century experience

Entrusted with the records for more than 1.5 million patients, the Regenstrief Medical Record System (RMRS) has evolved into a fast and comprehensive data repository used extensively at three hospitals on the Indiana University Medical Center campus and more than 30 Indianapolis clinics. The RMRS routinely captures laboratory results, narrative reports, orders, medications, radiology reports, registration information, nursing assessments, vital signs, EKGs and other clinical data. In this paper, we describe the RMRS data model, file structures and architecture, as well as recent necessary changes to these as we coordinate a collaborative effort among all major Indianapolis hospital systems, improving patient care by capturing city-wide laboratory and encounter data. We believe that our success represents persistent efforts to build interfaces directly to multiple independent instruments and other data collection systems, using medical standards such as HL7, LOINC, and DICOM. Inpatient and outpatient order entry systems, instruments for visit notes and on-line questionnaires that replace hardcopy forms, and intelligent use of coded data entry supplement the RMRS. Physicians happily enter orders, problems, allergies, visit notes, and discharge summaries into our locally developed Gopher order entry system, as we provide them with convenient output forms, choice lists, defaults, templates, reminders, drug interaction information, charge information, and on-line articles and textbooks. To prepare for the future, we have begun wrapping our system in Web browser technology, testing voice dictation and understanding, and employing wireless technology.

Proxy, health, and personal care preferences: implications for end-of-life care

The Institute of Medicine's report, “Approaching Death: Improving Care at the End of Life,” the American Medical Association's “Education for Physicians on End-of-Life Care” project, the Open Society Institute's “Project on Death in America,” and the “Last Acts” initiative sponsored by the Robert Wood Johnson Foundation have focused attention on improving the care of dying patients. These efforts include advance care planning and the use of written advance directives (ADs). Although previous studies have provided quantitative descriptions of patient preferences for life-sustaining treatment, including those documented in written ADs, to our knowledge open-ended written preferences have not been studied. Studies of these open-ended preferences could highlight issues with respect to quality end-of-life care. The purpose of this study was to explore the open-ended proxy, health, and personal care preferences of people with HIV as expressed in a written AD form.

Quality end-of-life care: patients' perspectives

CONTEXT

Quality end-of-life care is increasingly recognized as an ethical obligation of health care providers, both clinicians and organizations. However, this concept has not been examined from the perspective of patients.

OBJECTIVE

To identify and describe elements of quality end-of-life care from the patient's perspective.

DESIGN

Qualitative study using in-depth, open-ended, face-to-face interviews and content analysis.

SETTING

Toronto, Ontario.

PARTICIPANTS

A total of 126 participants from 3 patient groups: dialysis patients (n = 48), people with human immunodeficiency virus infection (n = 40), and residents of a long-term care facility (n = 38).

OUTCOME MEASURES

Participants' views on end-of-life issues.

RESULTS

Participants identified 5 domains of quality end-of-life care: receiving adequate pain and symptom management, avoiding inappropriate prolongation of dying, achieving a sense of control, relieving burden, and strengthening relationships with loved ones.

CONCLUSION

These domains, which characterize patients' perspectives on end-of-life care, can serve as focal points for improving the quality of end-of-life care.

A new model of advance care planning: observations from people with HIV

BACKGROUND

Although theoretical concepts from ethics and law have been applied, there is no conceptual model of advance care planning rooted in the perspective of individuals engaged in it.

OBJECTIVE

To develop a conceptual model of advance care planning by examining the perspectives of individuals engaged in it.

METHODS

In this qualitative research, we studied 140 individuals with human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome who were engaged in advance care planning. Respondents' experience with and opinions about advance care planning were noted in interviews that were audiotaped, transcribed, and analyzed.

RESULTS

The primary goal of advance care planning was to prepare for death, which entailed facing death, achieving a sense of control, and strengthening relationships.

CONCLUSIONS

We have developed a conceptual model of advance care planning rooted in the perspectives of individuals engaged in it. The model has implications for theory, research, and practice regarding end-of-life care.

Racial disparity in cardiac decision making: results from patient focus groups

BACKGROUND

While numerous studies suggest that African Americans receive fewer invasive cardiac procedures than whites, the basis for these treatment differences is not understood.

METHODS

We conducted focus group sessions with patients who had received treatment in the hospital or the emergency department within the preceding 3 months for ischemic heart disease at 2 urban, university-affiliated hospitals.

RESULTS

Discussions with patients identified the following factors that influenced their decision making: clarity, simplicity, and consistency of treatment recommendations; advice from friends and family about whether to accept recommendations; availability to speak with others who accepted similar recommendations; and having honest and caring physicians. African American patients identified the following additional factors that influenced their decision making: perceptions of health care discrimination; perceptions of undesirable physician behavior; faith in God to control one's destiny; and patient-physician camaraderie.

CONCLUSIONS

Participants identified common issues influencing health care decision making, regardless of race. However, additional factors were expressed only by African American participants. These factors conveyed racial differences in perceptions of the health care system that may, in part, contribute to differences in health care decision making and treatment.

California's county hospitals and the University of California graduate medical education system. Current issues and future directions

California's county hospitals train 45% of the state's graduate medical residents, including 33% of residents in the University of California system. This paper describes the interrelationships of California's county hospitals and the University of California (UC) graduate medical education (GME) programs, highlighting key challenges facing both systems. The mission of California's county health care systems is to serve all who need health care services regardless of ability to pay. Locating UC GME programs in county hospitals helps serve the public missions of both institutions. Such partnerships enhance the GME experience of UC residents, provide key primary care training opportunities, and ensure continued health care access for indigent and uninsured populations. Only through affiliation with university training programs have county hospitals been able to run the cost-effective, quality programs that constitute an acceptable safety net for the poor. Financial stress, however, has led county hospitals and UC's GME programs to advocate for reform in both GME financing and indigent care funding. County hospitals must participate in constructing strategies for GME reform to assure that GME funding mechanisms provide for equitable compensation of county hospitals' essential role. Joint advocacy will also be essential in achieving significant indigent care policy reform.

Reconceptualizing advance care planning from the patient's perspective

BACKGROUND

Traditional academic assumptions about advance care planning (ACP) include the following: (1) the purpose of ACP is preparing for incapacity; (2) ACP is based on the ethical principle of autonomy and the exercise of control; (3) the focus of ACP is completing written advance directive forms; and (4) ACP occurs within the context of the physician-patient relationship. These assumptions about ACP have never been empirically validated.

OBJECTIVE

To examine the traditional academic assumptions by exploring ACP from the perspective of patients actively participating in the planning process.

METHODS

Forty-eight patients (30 men and 18 women with a mean age of 48.3 years) who were undergoing hemodialysis were interviewed 6 months after receiving an advance directive form. Their experience of ACP was noted in interviews that were audiotaped, transcribed, and analyzed.

RESULTS

The participants said that their purpose in ACP was to prepare for death and dying, and their underlying goals included the exercise of control and an attempt to relieve burdens placed on loved ones. Advance care planning was viewed as a social process, and completing a written advance directive form was often regarded as unnecessary. Participants often involved close loved ones, but physicians infrequently.

CONCLUSIONS

The traditional academic assumptions are not fully supported from the perspective of patients involved in ACP. The patients we interviewed stated that (1) the purpose of ACP is not only preparing for incapacity but also preparing for death; (2) ACP is not based solely on autonomy and the exercise of control, but also on personal relationships and relieving burdens placed on others; (3) the focus of ACP is not only on completing written advance directive forms but also on the social process; and (4) ACP does not occur solely within the context of the physician-patient relationship but also within relationships with close loved ones.

Can raters consistently evaluate the content of focus groups?

Focus groups are increasingly being used to provide insights to researchers and policy makers. These data complement quantitative approaches to understanding the world. Unfortunately, quantitative and qualitative methodologies have often been viewed as antithetical, rather than complementary, strategies. While focus groups can clearly generate rich information that is unobtainable through other quantitative methods, it is important to determine the degree to which different raters can consistently extract information from transcripts. Thus, our goal was to quantify agreement in the interpretation of transcripts from patient and physician focus groups, using decision-making in ischemic heart disease as a model. We used data from focus groups with both patients and physicians that sought to identify factors affecting diagnostic and treatment decisions in ischemic heart disease. Three raters independently reviewed transcribed audiotapes from focus groups of patients with ischemic heart disease, as well as focus groups of physicians who care for these patients. We found that raters could not distinguish between major and minor factors reliably. More troubling, however, is that consistency regarding the apparently straightforward judgment as to the mere presence or absence of a factor was difficult to achieve. In particular, the three raters of each transcript failed to agree on between one third and one half of the factors. This reasonably high level of disagreement occurred despite the raters: (1) having generated the individual factors themselves based upon their reading a random sample of actual transcripts and (2) being trained in the use of rating forms (including standard definitions of themes). These data suggest that if a single rater evaluates focus group transcripts, as is commonly done, judgments may not be reproducible by other raters. Moreover, a single rater may not extract all important information contained in the transcripts.

In vitro transesterification of cocaethylene (ethylcocaine) in the presence of ethanol. esterase-mediated ethyl ester exchange esterase-mediated ethyl ester exchange

This study reports that cocaethylene undergoes an esterase-mediated ethyl ester exchange with ethanol, resulting in an increase in the apparent in vitro t1/2, compared with control conditions. Homogenized liver from male Sprague Dawley rats in pH 7.4 phosphate buffer was centrifuged at 9000g, and the resulting supernatant (S9) fraction was collected. Tubes containing the rat S9 fraction and 50 microM cocaethylene plus aqueous buffer (control), 50 mM ethanol, or 51. 3 mM 2H6-ethanol were incubated at 37 degrees C for 4 hr. Samples were collected from the incubation tubes at various times, extracted with a solid-phase extraction system, and assayed for cocaethylene and 2H5-cocaethylene by GC/MS. Concentration-time profiles were constructed and kinetic parameters were determined. The experiment was repeated in the presence of specific and nonspecific esterase inhibitors. Enzyme kinetic parameters were also determined. Cocaethylene underwent ethyl ester exchange, being converted to 2H5-cocaethylene in the presence of 2H6-ethanol. The average apparent in vitro t1/2 value for cocaethylene (13.0 +/- 1.4 min) incubated with the S9 fraction and buffer only was increased approximately 5-fold (67.8 +/- 0.3 min) in the presence of ethanol. Formation of 2H5-cocaethylene was totally blocked with the addition of bis-(p-nitrophenyl)phosphate but was unaffected by physostigmine. The intrinsic metabolite formation clearance of 2H5-cocaethylene from cocaethylene and 2H6-ethanol (1.92 +/- 0.03 microl/min.mg protein) was several times greater than the corresponding value for cocaethylene formation from cocaine and ethanol (0.94 +/- 0.01 microl/min.mg protein) or 2H6-ethanol (0.87 +/- 0.04 microl/min.mg protein).

Characterization of an inwardly rectifying potassium channel in the rabbit superior lacrimal gland

PURPOSE

To characterize the properties of an inwardly rectifying K+ (KIR) current in fresh, enzymatically isolated acinar cells from the rabbit superior lacrimal gland.

METHODS

New Zealand White rabbits of both sexes were killed by injecting 45 mg/kg pentobarbital sodium, and the glands were excised. Single acinar cells were isolated enzymatically from these glands. Standard patch-clamp techniques were used to record ion currents.

RESULTS

Hyperpolarizing voltages evoked KIR currents that had a conductance of 2.7 +/- 0.16 nS (n = 6) in the range -50 mV to -160 mV. The KIR current was activated with steep voltage dependence on hyperpolarization, and the conductance was approximately dependent on the square root of the external K+ concentration. Increasing the pipette Ca2+ concentration from 10(-9) M to 10(-6) M increased the conductance to 5.3 +/- 0.45 nS (n = 7). Internal substitution of K+ with various cations gave the following permeability sequence: K+ (1.0) > Rb+ (0.83) > Li+ (0.15). The KIR current was inhibited by Ba2+ (100 microns), tetraethylammonium (10 mM), and Cs+ (5 mM) but was insensitive to 4-aminopyridine (5 mM). The single-channel conductance was 43 +/- 2.7 pS (n = 11), and the relationship between between single-channel conductance (gamma) and external K+ concentration ([K]o) is given by: gamma = 7.04[K]o0.37 (pS, r2 = 0.99, P < 0.05). The relationship between [K]o and zero current potential (Erev) is given by: Erev = 35.5 log[K]o - 77.8 (mV; r2 = 0.99, P < 0.05).

CONCLUSIONS

The KIR current identified in these lacrimal acini has a similar dependence on [K]o as other inward rectifiers of excitable tissues and exocrine glands. However, this study highlights that there are interspecies variations and similarities between KIR channels that could be related to their individual physiological roles. The authors' investigations suggest that one role of the KIR channel in the rabbit superior lacrimal gland acinar cells is to set and stabilize the resting membrane potential. However, this KIR channel may also be involved in secretion, as has been shown to occur in the sheep parotid gland.

Comparative Study of the Effects of Erythromycin and Roxithromycin on Action Potential Duration and Potassium Currents in Canine Purkinje Fibers and Rabbit Myocardium

BACKGROUND: Erythromycin and roxithromycin are macrolide antibiotics in common clinical use. Erythromycin occasionally produces life-threatening arrhythmias (torsades de pointes) by blocking the outward potassium current responsible for repolarization of the cardiac action potential. METHODS AND RESULTS: We used standard cellular electrophysiological and whole-cell patch-clamping techniques to compare the relative efficacy of erythromycin and roxithromycin in prolonging cardiac action potential in canine Purkinje fibers and in blocking individual outward potassium currents in isolated rabbit ventricular myocytes. We demonstrated significant prolongation of action potential duration in canine Purkinje fibers by erythromycin but not roxithromycin at a concentration of 100 µM. The delayed rectifier, the outward potassium current thought to be most sensitive to modulation by drugs, was significantly depressed by both agents at concentrations of >/=30 µM in isolated rabbit ventricular myocytes. Both drugs had similar potencies (26% and 21% reduction by 30 µM erythromycin and roxithromycin, respectively, and 50% and 36% reduction by 100 µM erythromycin and roxithromycin). Neither agent significantly blocked other potassium currents (including the transient outward current). CONCLUSIONS: Taking into account normally observed peak blood concentrations of these agents in clinical use and the fact that roxithromycin is not normally administered intravenously, we conclude that the risk of proarrhythmia during normal clinical use of oral roxithromycin is extremely remote.

Examination of racial differences in management of cardiovascular disease

OBJECTIVES

We sought to identify the clinical characteristics associated with, and to investigate the impact of cohort selection criteria on, interracial use of invasive cardiac procedures and to determine survival.

BACKGROUND

Although interracial differences in the use of invasive cardiac procedures have been previously reported, the underlying reasons are not known.

METHODS

A retrospective cohort study was conducted at a Veterans Affairs Medical Center. Study patients were evaluated for cardiovascular disease between January 1 and December 31, 1993.

RESULTS

The study included 1,406 male patients (85% white, 58% married), with a mean age of 63.4 years. African Americans were less likely than whites to undergo procedures (cardiac catheterization: odds ratio [OR] 0.37, 95% confidence interval [CI] 0.24 to 0.58; coronary angioplasty: OR 0.60, 95% CI 0.25 to 1.49; coronary bypass surgery: OR 0.22, 95% CI 0.08 to 0.63; any procedure: OR 0.32, 95% CI 0.21 to 0.50). On bivariate analysis, patients who underwent cardiac procedures were more likely to be younger, married and reside nonlocally and less likely to have severe comorbid disease; however, African Americans were less likely to be married and to reside nonlocally and more likely to have severe comorbid disease. Cohorts adjusting for referral status and specified cardiac diagnoses reduced or reversed interracial treatment differences. Thirty-day and 1-year survival rates (96% and 87.6%, respectively) were equivalent.

CONCLUSIONS

Racial disparity in invasive cardiac procedure use may be partially explained by clinical differences and cohort selection bias. Despite treatment differences, survival rates were equivalent in African Americans and whites.

Modulation of the Electrophysiologic Actions of E-4031 and Dofetilide by Hyperkalemia and Acidosis in Rabbit Ventricular Myocytes

BACKGROUND: E-4031 and dofetilide are new class III antiarrhythmic agents that inhibit the rapid component of the delayed rectifier potassium channel (I(Kr)); however, the effectiveness of many antiarrhythmic drugs in ischemic conditions is uncertain. METHODS AND RESULTS: We modeled two components of ischemia, hyperkalemia (9.6 mM) and acidosis (pH 6.8), in voltage-clamped single rabbit ventricular myocytes to help determine the effect of ischemia on the action of these two drugs. In physiologic solution both E-4031 and dofetilide blocked I(Kr) and significantly reduced total outward current. In hyperkalemic solution, both E-4031 and dofetilide showed significantly reduced blockade of I(Kr), while in acidotic solution dofetilide showed significantly reduced blockade of I(Kr) and E-4031 showed a trend to reduced blockade. Neither drug significantly reduced total outward current in hyperkalemic or acidotic solutions. CONCLUSIONS: In these conditions, E-4031 and dofetilide demonstrate reduced blockade of I(Kr), resulting in loss of class III effect. Furthermore, the complete loss of blocking effect on total outward current during simulated ischemia suggests increases of other repolarizing currents also contribute to loss of class III effect.

Molecular cloning and expression of a chloride ion channel of cell nuclei

Ion channels are known to be present on the plasma membrane of virtually all cells and have been found on the membranes of various intracellular organelles. However, until recently they were believed not to occur at the nuclear membrane. In this study we describe the molecular cloning and characterization of a nuclear ion channel protein, designated nuclear chloride channel-27 (NCC27), from the human myelomonocytic cell line, U937. NCC27 is a novel chloride ion channel protein that was found to localize principally to the cell nucleus. Its only known homologue is a bovine chloride ion channel protein (p64) believed to localize to internal organelles. NCC27 therefore represents the first human member of a new class of organellar chloride ion channel proteins.

Leptin is a four-helix bundle: secondary structure by NMR

Leptin is a signaling protein that in its mutant forms has been associated with obesity and Type II diabetes. The lack of sequence similarity has precluded analogies based on structural resemblance to known systems. Backbone NMR signals for mouse leptin (13C/15N -labeled) have been assigned and its secondary structure reveals it to be a four-helix bundle cytokine. Helix lengths and disulfide pattern are in agreement with leptin as a member of the short-helix cytokine family. A three-dimensional model was built verifying the mechanical consistency of the identified elements with a short-helix cytokine core.

The Novel Class III Antiarrhythmic Agent MS-551 Blocks the Cardiac Inward Rectifier With Greater Potency Than Sotalol or E-4031: Possible Relevance to Reverse Use Dependence

BACKGROUND: The tendency for the electrophysiologic effect of class III antiarrhythmic agents (action potential prolongation) to be diminished at faster heart rates represents a major drawback of this class of drug and is usually referred to as "reverse use dependence." A novel class III agent, MS-551, has recently been reported to exhibit less reverse use dependence than E-4031. We set out to investigate whether this observation may be due to differential blockade of the inward rectifier current (i(K1)) by these drugs. METHODS AND RESULTS: We recorded i(K1) using single channel methods and cell attached patch configurations, with standard patch clamp technology. Neither E-4031 nor racemic sotalol in concentrations up to 100 µM had any significant effect on the open probability or kinetics of i(K1) without altering the single-channel conductance. Openings to subconductance levels were abolished in three of six patches in which they had been frequently present in the absence of drug. MS-551 had no effect on mean channel open time but increased the slower component of the closed time. CONCLUSIONS: MS-551, unlike E-4031 and sotalol, appears to produce significant blockade of the inwardly rectifying potassium channel at clinically relevant concentrations. We propose that this might provide a partial explanation for the observed differences in their response to rate changes.

Risk factors for nonelective hospital readmissions

We previously reported a predictive model that identified potentially modifiable risk factors for nonelective readmission to a county hospital. The objectives of this study were to determine if those risk factors were generalizable to a different population. We found that the previously reported risk factors were generalizable, and other potentially modifiable risk factors were identified in this population of veterans. However, further research is needed to establish whether or not the risk factors can be modified and whether or not modification improves outcomes.

Kainic acid blocks a TTX-sensitive sodium channel in retinal horizontal cells of the turtle (Pseudemys scripta elegans)

The aim of this study was to investigate the effects of excitatory amino acids on channels found in horizontal cell membranes using patch-clamp techniques. We unexpectedly found that the excitatory amino acid receptor agonist, kainic acid, reversibly inhibited the transient tetrodotoxin (TTX)-sensitive Na+ current in isolated horizontal cell bodies and axons from the retina of the turtle (Pseudemys scripta elegans). The effect of kainic acid was antagonized by the glutamate receptor antagonist 6-cyano-7-nitroquinoxaline-2,3-dione. Kainic acid activated a non-selective cation current, a finding that was consistent with previous reports, and which would account for the kainate induced depolarisation of these cells. The inhibition of the transient TTX-sensitive Na+ current by kainic acid might be important in the modification of the kinetics of responses to excitatory amino acid analogues often observed during intracellular recording from these cells.

Chloride ion channels are associated with adherence of lymphatic endothelial cells

We have examined the role of chloride ion channels as part of the control mechanism for adherence and growth of lymphatic endothelial cells. The chloride channel inhibitor N-phenylanthranilic acid (0.1 mM) inhibited the initial adherence of previously nonadherent cells in the period up to 3 hr following seeding onto gelatin-coated culture dishes. The potassium channel inhibitor 4-aminopyridine (1 mM) had no effect on the rate of cell adherence. N-Phenylanthranilic acid had no effect when added to confluent monolayers of cells that had been growing for 3 days. This, and the observation that N-phenylanthranilic acid did not affect the ultrastructure of the cells, suggested that plasma membrane chloride channels are involved in the initial signaling cascade triggered when lymphatic endothelial cells begin to adhere to a substrate.

Effect of Dofetilide and d-Sotalol on the ATP-Sensitive Potassium Channel of Rabbit Ventricular Myocytes

BACKGROUND: The ability of dofetilide and d-sotalol to maintain their class III action during ischemia is uncertain. We investigated the effect of these two drugs on the ATP-sensitive potassium channel (I(KATP)), which plays a major role in ischemia-induced action potential duration shortening. METHODS AND RESULTS: The activity of I(KATP) channels was studied in excised membrane patches of single ventricular myocytes, obtained by standard enzymatic dissociation techniques from New Zealand white rabbits. Dofetilide demonstrated a dose-dependent block of I(KATP) with an EC(50) of 51 +/- 1 µM in inside-out patches, Its ability to block the channel was substantially less when applied to the external membrane surface. d-Sotalol significantly blocked I(KATP) (42% reduction) at a concentration of 10 µM but not at 1 µM. As with dofetilide, its ability to block I(KATP) was reduced when applied externally. CONCLUSIONS: We conclude that dofetilide and d-sotalol block the ATP-sensitive potassium channel, but dofetilide does so only at concentrations much greater than those required for block of the delayed rectifier potassium channel. d-Sotalol in contrast shows modest blockade of I(KATP) at concentrations in the upper range of those seen during its clinical use.

Characterization of the properties of cocaine in blood: blood clearance, blood to plasma ratio, and plasma protein binding

As part of a study to examine cocaine disposition and interaction with ethanol, it was necessary to characterize various properties of cocaine in the blood of the experimental animal. All studies were conducted using blood from healthy adult male Sprague-Dawley rats. Cocaine was incubated in whole blood at 37 degrees C at concentrations of 500-4000 ng/mL. The apparent first-order rate constant for cocaine loss was independent of concentration. Blood clearance, calculated assuming blood volume to be 64 mL/kg, was estimated to be 0.056 +/- 0.003 mL/(min.kg); a value considerably smaller than estimates of systemic clearance. The addition of NaF increased the rate of loss to form benzoylecgonine, as a result of increased chemical degradation and as a consequence of increased pH (to pH 8.0 over 30 h). This NaF-enhanced degradation was abolished when NaF was added to blood buffered to pH 7.4. Ethanol had no influence on cocaine degradation, and there was no evidence of cocaethylene (ethylcocaine) formation. Blood to plasma ratios determined in spiked and authentic samples were constant (0.94-1.05 and 0.99-1.03, respectively) and independent of concentration (100-1500 ng/mL) and pH (7.2-7.6). This ratio was not influenced by NaF or ethanol. The unbound fraction (fu) of cocaine determined in spiked plasma varied from 0.62 to 0.63 over the concentration range (75-2025 ng/mL). Ethanol had no effect on binding. The values for fu determined from authentic blood samples taken from rats dosed intravenously with cocaine (10 mg/kg) ranged from 0.67 to 0.69 (over the concentration range 300-1500 ng/mL). Cocaine plasma protein binding was independent of concentration but depended upon plasma pH (fu, 0.765 and 0.486, at pHs 7.0 and 7.8, respectively.