Small Fiber Neuropathy

PURPOSE OF REVIEW

This narrative review aims to summarize advances in the field of small fiber neuropathy made over the last decade, with emphasis on novel research highlighting the distinctive features of SFN.

RECENT FINDINGS

While the management of SFNs is ideally aimed at treating the underlying cause, most patients will require pain control via multiple, concurrent therapies. Herein, we highlight the most up-to-date information for diagnosis, medication management, interventional management, and novel therapies on the horizon. Despite the prevalence of small fiber neuropathies, there is no clear consensus on guidelines specific for the treatment of SFN. Despite the lack of specific guidelines for SFN treatment, the most recent general neuropathic pain guidelines are based on Cochrane studies and randomized controlled trials (RCTs) which have individually examined therapies used for the more commonly studied SFNs, such as painful diabetic neuropathy and HIV neuropathy. The recommendations from current guidelines are based on variables such as number needed to treat (NNT), safety, ease of use, and effect on quality of life.

Cost and Utility of Routine Contrast-Enhanced Neck MRA in a Pediatric MRI Stroke Evaluation Protocol

BACKGROUND AND PURPOSE

Cervical arterial dissection is one of the frequent causes of pediatric arterial ischemic stroke. Out of concern for missing cervical arterial dissection in patients in whom pediatric stroke is suspected, our tertiary children's hospital added contrast-enhanced 3D neck MR angiography to every pediatric stoke work-up. This research investigated whether the routine use of contrast-enhanced neck MRA in our MR imaging stroke protocol ever detected a cervical arterial abnormality when the DWI, SWI/gradient recalled-echo, or circle of Willis MRA findings from the brain MR imaging were reported as normal.

MATERIALS AND METHODS

The institutional PACS data base was searched for stroke protocol MRIs that included DWI, gradient recalled-echo or SWI, circle of Willis MRA, and 3D contrast-enhanced neck MRA in patients younger than 18 years of age with examinations performed between September 2010 and June 2017.

RESULTS

In only a single case (0.15%) were the DWI, SWI/gradient recalled-echo, or circle of Willis MRA findings all separately reported as normal and the contrast-enhanced neck MRA findings reported as abnormal. To reach these findings, we screened 681 patients, which would have resulted in an estimated >$200,000 in Medicare charges and $80,000 in of out-of-pocket cost to patients.

CONCLUSIONS

In our large series, the addition of a routine contrast-enhanced neck MRA to our pediatric stroke MR imaging protocol was of extremely low yield. We believe the use of neck MRA should reasonably be limited to cases in which abnormalities are initially detected on standard brain sequences or to patients with atypical presentation or recurrent pathology.

Personal characteristics and outcomes of individuals with developmental disabilities who need support for self-injurious behaviour

BACKGROUND

For people with intellectual and developmental disabilities, self-injurious behaviour (SIB) can have serious negative effects on both health and quality of life. This descriptive analysis will provide information on the characteristics and outcomes of a subsample of individuals who are identified as needing some or extensive support for SIB in the National Core Indicators Adult Consumer Survey sample.

METHODS

The data for this analysis come from states that participated in the 2015-2016 data collection cycle of National Core Indicators Adult Consumer Survey which is a face-to-face survey of adults receiving services through state developmental disability agencies.

RESULTS

The characteristics and outcomes of individuals who need at least some support for SIB differ from those of individuals with intellectual and developmental disabilities who do not need support for SIB. Individuals with SIB support needs, for example, tend to live in more structured settings, have fewer relationships, less inclusion in their communities and poorer employment outcomes.

CONCLUSIONS

The exploratory descriptive analysis concludes with suggested recommendations for more standardised definitions of SIB in public systems, enhanced behaviour plan protocols and the need for additional research.

Safety of sublingual immunotherapy Timothy grass tablet in subjects with allergic rhinitis with or without conjunctivitis and history of asthma

BACKGROUND

Patients with asthma may be more susceptible to adverse events (AEs) with sublingual immunotherapy tablet (SLIT-tablet) treatment, such as severe systemic reactions and asthma-related events. Using data from eight trials of grass SLIT-tablet in subjects with allergic rhinitis with/without conjunctivitis (AR/C), AE frequencies were determined in adults and children with and without reported asthma.

METHODS

Data from randomized, double-blind, placebo-controlled trials of Timothy grass SLIT-tablet MK-7243 (2800 BAU/75 000 SQ-T, Merck/ALK-Abelló) were pooled for post hoc analyses. Subjects with uncontrolled and severe asthma were excluded from the trials. Frequencies for treatment-emergent AEs (TEAEs), local allergic swelling (mouth or throat), systemic allergic reactions, and asthma-related treatment-related AEs (TRAEs) were calculated.

RESULTS

Among adults (n = 3314) and children (n = 881), 24% and 31%, respectively, had reported asthma. No serious local allergic swellings or serious systemic allergic reactions occurred in subjects with asthma treated with SLIT-tablet. There was no evidence of increased TEAEs, systemic allergic reactions, or severe local allergic swellings in adults or children with asthma treated with grass SLIT-tablet versus subjects without asthma in or outside of pollen season. There were 6/120 asthma-related TRAEs assessed as severe with grass SLIT-tablet and 2/60 with placebo, without a consistent trend among subjects with and without asthma (5 and 3 events, respectively).

CONCLUSIONS

In the AR/C subjects with reported well-controlled mild asthma included in these studies, grass SLIT-tablet did not increase TEAE frequency, severe local allergic swelling, or systemic allergic reactions versus subjects without asthma. There was no indication that treatment led to acute asthma worsening.

How to adjust media recommendations on reporting suicidal behavior to new media developments

This study examines the inclusion of preventive factors and new media developments in media recommendations on suicide reporting. Of the 193 member states of the United Nations screened for media recommendations, information was available for 74 countries. Similarities and differences in their contents were analyzed by cluster analysis. Results indicate that of these 74 countries, 38% have national suicide prevention programs, 38% have media recommendations, and 25% have press codes including suicide reporting. Less than 25% of the media recommendations advise against mentioning online forums, suicide notes, pacts, clusters, hotspots, details of the person, and positive consequences. No more than 15% refer to self-help groups, fictional and online reporting. We conclude that media recommendations need to be revised by adding these preventive factors and by including sections on new media reporting.

Effects of gender and age on serum concentrations of antidepressants under naturalistic conditions

Therapeutic drug monitoring (TDM) data of antidepressant drugs are often evaluated using homogeneous samples of selected individuals without psychiatric or somatic comorbidity. These data may have limitations in transferability to everyday clinical practice. Hence, studies under naturalistic conditions are important to clarify the full clinical relevance of TDM of antidepressants. TDM analyses were retrospectively evaluated for a 3-year period from 2008 to 2010. The influence of gender and age on dose-corrected serum concentrations of antidepressants was examined in a standard clinical setting. 693 TDM analyses of amitriptyline and nortriptyline (AMI + NOR), 160 of citalopram (CIT), 152 of clomipramine and N-clomipramine (CLO + N-CLO), 272 of doxepine and N-doxepine (DOX + N-DOX), 359 of escitalopram (ESC), 198 of fluoxetine and N-fluoxetine (FLU + N-FLU), 92 of maprotiline (MAP), 888 of mirtazapine (MIR), and 77 of sertraline (SER) remained in the sample. Females had significantly higher dose-corrected serum concentrations of AMI + NOR (32 %), CIT (29 %), DOX + N-DOX (29 %), and MIR (20 %), and patients older than 60 years had significantly higher dose-corrected serum concentrations of AMI + NOR (21 %), CIT (40 %), DOX + N-DOX (48 %), MAP (46 %), MIR (24 %), and SER (67 %). Comparing the two extreme groups, females >60 years showed a remarkably higher dose-corrected serum concentration of AMI + NOR (52 %), CIT (78 %), DOX + N-DOX (86 %), and MIR (41 %) in contrast to males ≤60 years. Gender and age have a significant influence on the serum concentrations of different antidepressant drugs, and additive effects must be considered. TDM is recommended to reduce the risk of adverse effects due to supratherapeutic serum levels, also in a naturalistic clinical setting.

Wisconsin Comorbidity Assessment Scale (WCAS): A novel, comprehensive, performance-based assessment scale of geriatric syndromes and medical comorbidities in older cancer patients

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Background: Elderly patients with cancer have potential for multiple geriatric syndromes that influence treatment and outcomes. No single clinical assessment tool has targeted all the major geriatric syndromes and their interaction on cancer management and outcomes. We developed WCAS to evaluate cognitive and physical function, risk of falls and gait disorders, polypharmacy, and medical comorbidities. Methods: Eighteen newly diagnosed patients with breast cancer (age 55–82), were enrolled prior to cancer treatment. Cognitive function was evaluated with a comprehensive battery of neuropsychological tests targeting the domains of memory, executive function, attention, language, and praxis. Physical function skills were assessed with novel performance-based tasks (e.g., bed-making) and computerized assessments of balance, gait and risk of falls. Cancer treatment included surgery in all patients with variable use of adjuvant radiation and medical therapy. WCAS was administered at baseline and at month 6. Results: Ten subjects have completed both baseline and month 6 visits. Surgical treatment occurred at a mean of ten days after baseline assessment (SD 6.7). The mean (SD) of the age, years of education and baseline Mini Mental Status Exam (MMSE) was 66 years (7.3), 15.2 years (3.7) and 29.3 (1.1). From baseline to month six assessment performance on the WAIS Digit Symbol test, a measure of working memory and processing speed, declined (mean change −11.7, p<0.01). Likewise, the performance on the WAIS letter number sequence test (mean change −1.3, p=0.09) and the MMSE (mean change −1.1, p=0.12) declined. Interestingly, four subjects with pre-existing hypothyroidism on replacement treatment showed a greater decline (p<0.01) in memory than those without this common condition. Conclusions: Findings indicate that breast cancer diagnosis and therapy can be associated with significant decline in aspects of cognition in older adults with cancer. These changes can last at least 6 months and are more pronounced in those with hypothyroidism. Larger, longer term prospective studies utilizing WCAS are necessary to confirm our preliminary findings.

No significant financial relationships to disclose.

A multicenter, randomized, double-blind, placebo-controlled, dose-finding trial of a long-acting formulation of octreotide in promoting weight loss in obese adults with insulin hypersecretion

OBJECTIVE

To compare changes in weight in obese patients who received long-acting octreotide (octreotide LAR) at one of three dose levels (20, 40, or 60 mg) or placebo over 6 months and to identify the lowest dose of octreotide LAR that safely achieved optimal weight loss.

DESIGN

Randomized, double-blind, placebo-controlled trial of octreotide LAR at three dose levels.

PATIENTS

A total of 172 adults (28 men and 144 women) with at least moderate obesity (body mass index (BMI) range 30-65 kg/m2) and evidence of insulin hypersecretion were enrolled. Patients were predominantly either Caucasian (50.0%) or African American (45.3%). The mean age (38 +/- 11 year), weight (110.7 +/- 23 kg), and BMI (39.8 +/- 6.5 kg/m2) were similar across the four treatment groups.

MEASUREMENTS

Efficacy measures included weight, BMI, fasting serum glucose; triglycerides; percentage of total body fat and abdominal fat as measured by dual-energy X-ray absorptiometry; skin fold thickness; waist-to-hip circumference; leptin; percentage of carbohydrates, fat, and protein ingested; nutritional evaluation (including dietary analysis--3-day food record); quality of life (QoL; using the Impact of Weight on Quality of Life-Lite); Beck Depression Inventory; and Carbohydrate Craving Questionnaire. Safety measures included medical history, vital signs, physical examinations, hematology, blood chemistries, thyroid function tests, hemoglobin A1c, gallbladder ultrasound, electrocardiograms, and adverse events.

RESULTS

After 6 months of treatment, patients receiving 40 or 60 mg of octreotide LAR experienced statistically significant weight loss compared to baseline, with mean differences from placebo in percent weight change of -1.98 and -1.87%, respectively. This finding was accompanied by statistically significant mean decreases in BMI compared to baseline, that is, a mean decrease of 0.73 and 0.79 kg/m2 for the 40 and 60 mg treatment arms, respectively. The observed weight loss was progressive during the 6-month treatment in the two higher dose groups. The lowest dose to reach statistical significance in weight loss after 6 months' treatment was 40 mg. Post hoc analysis revealed a 3.5-3.8% weight loss at month 6 in the two higher dose groups among Caucasian patients having insulin secretion greater than the median of the cohort, defined as CIR(gp) (corrected insulin response at the glucose peak) > or = 1.43. There were no statistically significant changes in QoL scores, body fat, leptin concentration, Beck Depression Inventory, or macronutrient intake. Mean changes of blood glucose AUC(0-180 min) during an oral glucose tolerance test in patients taking octreotide LAR were 39-40 mg/dl h higher than those on placebo. A total of 7-21% of the patients taking octreotide LAR reached a 5% or greater decrease in body weight from Baseline, compared to 11% for the placebo group. This was not statistically significant. The most common adverse events included diarrhea, headache, cholelithiasis, nausea, and abdominal pain.

CONCLUSION

Octreotide LAR given at 40 or 60 mg resulted in statistically significant weight loss. A post hoc analysis stratifying patients by race and CIR(gp) indicated that Caucasian patients with the greater degree of insulin hypersecretion appeared to derive the most benefit from treatment. The observed safety profile was consistent with the known effects of octreotide from previous studies.

Plasma vascular endothelial growth factor in acute mountain sickness

STUDY OBJECTIVES

To investigate the hypothesis that an increase in circulating vascular endothelial growth factor (VEGF) occurs in mountaineers at high altitude, particularly in association with acute mountain sickness (AMS) and/or low hemoglobin oxygen saturation.

DESIGN

: Collection of medical histories, AMS scores, plasma samples, and arterial oxygen saturation (SaO(2)) measurements from mountaineers at 1,500 feet (sea level) and at 14,200 feet.

SETTING

Mount McKinley ("Denali"), AK.

PARTICIPANTS

Sixty-six mountaineers.

INTERVENTIONS

None.

MEASUREMENTS AND RESULTS

Plasma VEGF at 14,200 feet was not increased in any group. In fact, plasma VEGF was significantly lower in subjects who did not develop AMS (53 +/- 7.9 pg/mL; mean +/- SEM; n = 47) compared to control subjects at sea level (98.4 +/- 14.3 pg/mL; n = 7; p = 0.005). Plasma VEGF at 14, 200 feet for subjects with AMS (62 +/- 12 pg/mL; n = 15) did not differ significantly from subjects at 14,200 feet without AMS, or from control subjects at sea level. Of a small number of subjects with paired specimens at sea level and at base camp (n = 5), subjects who exhibited a decrease in plasma VEGF at 14,200 feet were those who did not develop AMS. Neither SaO(2), prior AMS, AMS symptom scores, or acetazolamide use were correlated with plasma VEGF.

CONCLUSIONS

Subjects at high altitude who do not develop AMS have lower plasma VEGF levels compared to control subjects at sea level. Plasma VEGF at high altitude is not elevated in association with AMS or hypoxia. Sustained plasma VEGF at altitude may reflect a phenotype more susceptible to AMS.

An assessment of paramedic performance during invasive airway management

OBJECTIVE

To assess the performance of paramedics, in a newly-initiated prehospital program, during invasive airway management.

METHODS

An audit of paramedic call reports for a 12-month period from January to December 1997 was performed. Call reports that documented invasive airway management were retrieved and relevant data were extracted using a preformulated data-entry form.

RESULTS

Paramedics attempted tracheal intubation in 453 patients and were successful in 408 (90.1%); 331 of the patients were in cardiopulmonary arrest with vital signs absent (VSA), 101 had medical emergencies, and 21 had trauma-related problems. In the VSA cohort, the tracheas of 96% of the patients were intubated successfully; 80.1% on the first attempt, 10.6% on the second, 4.5% on the third, and 0.9% after more than three attempts. In the medical cohort, the tracheas of 74.3% of the patients were intubated; 60.4% on the first attempt, 11.9% on the second, and 2.9% on the third. In the trauma cohort, 71.4% of the intubations were successful; 66.6% on the first attempt, 26.6% on the second, and 6.6% on the third. There was a difference (p < 0.001) in the incidence of successful intubations comparing the VSA cohort with the medical/trauma cohorts. There was also a difference (p < 0.001) between the success rate for nasal intubations (43 of 68, 63% of patients successfully intubated) and that for oral intubation (365 of 385, 94% of patients).

CONCLUSION

This study demonstrated a difference in the paramedics' success rates for tracheal intubation in VSA patients compared with those with preserved airway reflexes and a lower success rate for nasal vs oral tracheal intubation. These differences may be due to inadequate training, technical difficulties experienced in the field, or lack of sufficient exposure to medical/trauma scenarios to gain management experience. Future training to address these issues, both in the initial training phase and in the continuing education program, may be beneficial in improving performance.

Improved out-of-hospital cardiac arrest survival through the inexpensive optimization of an existing defibrillation program: OPALS study phase II. Ontario Prehospital Advanced Life Support

CONTEXT

Survival rates for out-of-hospital cardiac arrest are low; published survival rates in Ontario are only 2.5%. This study represents phase II of the Ontario Prehospital Advanced Life Support (OPALS) study, which is designed to systematically evaluate the effectiveness and efficiency of various prehospital interventions for patients with cardiac arrest, trauma, and critical illnesses.

OBJECTIVE

To assess the impact on out-of-hospital cardiac arrest survival of the implementation of a rapid defibrillation program in a large multicenter emergency medical services (EMS) system with existing basic life support and defibrillation (BLS-D) level of care.

DESIGN

Controlled clinical trial comparing survival for 36 months before (phase I) and 12 months after (phase II) system optimization.

SETTING

Nineteen urban and suburban Ontario communities (populations ranging from 16 000 to 750 000 [total, 2.7 million]).

PATIENTS

All patients who had out-of-hospital cardiac arrest in the study communities for whom resuscitation was attempted by emergency responders.

INTERVENTIONS

Study communities optimized their EMS systems to achieve the target response interval from when a call was received until a vehicle stopped with a defibrillator of 8 minutes or less for 90% of cardiac arrest cases. Working both locally and provincially, communities implemented multiple measures, including defibrillation by firefighters, base paging, tiered response agreements with fire departments, continuous quality improvement for response intervals, and province-wide revision and implementation of standard dispatch policies. All response times were obtained from a central dispatch system.

MAIN OUTCOME MEASURE

Survival to hospital discharge.

RESULTS

The 4690 cardiac arrest patients studied in phase I and the 1641 in phase II were similar for all clinical and demographic characteristics, including age, sex, witnessed status, rhythm, and receipt of bystander cardiopulmonary resuscitation. The proportion of cases meeting the 8-minute response criterion improved (76.7% vs 92.5%; P<.001) as did most median response intervals. Overall survival to hospital discharge for all rhythm groups combined improved from 3.9% to 5.2 % (P = .03). The 33% relative increase in survival represents an additional 21 lives saved each year in the study communities (approximately 1 life per 120000 residents). The charges were estimated to be US $46900 per life saved for establishing the rapid defibrillation program and US $2400 per life saved annually for maintaining the program.

CONCLUSION

An inexpensive, multifaceted system optimization approach to rapid defibrillation can lead to significant improvements in survival after cardiac arrest in a large BLS-D EMS system.

Vascular endothelial growth factor in pulmonary hypertension

The best studied of the endothelial cell specific growth factors, VEGF, is present in alveolar and bronchial epithelial cells, in vascular smooth muscle cells, and in macrophages. The gene encoding VEGF is abundantly present in lung tissue and is induced by short-term and long-term hypoxia, as well as by prostacyclin, prostaglandin E2, and cyclic AMP. In the case of prostaglandin-stimulated gene upregulation protein kinase A (PKA) is involved. Suramin, an inhibitor of growth factor receptor binding inhibits the development of chronic hypoxic pulmonary hypertension in rats. Further evidence is necessary to link VEGF with pulmonary hypertensive vascular remodeling. This requires the development of antibodies directed against VEGF or against VEGF receptors and gene transfection or antisense strategies.

Head-up tilt and hemodynamic changes during orthostatic hypotension in patients with supine hypertension

OBJECTIVES

This study assessed the mechanism(s) of the decrease in upright blood pressure in patients with supine hypertension by using the tilt test and a hemodynamic approach.

BACKGROUND

Orthostatic hypotension in patients with supine hypertension creates a pathophysiologic and therapeutic dilemma.

METHODS

We studied 28 consecutive patients with history of orthostatic intolerance amounting to recurrent syncope in 13 of them (15 men, 13 women; mean [SD] age 65 +/- 11 years). They all had supine hypertension (systolic blood pressure > 160 mm Hg) and orthostatic hypotension (found to be a decrease in systolic blood pressure > 30 mm Hg during tilt test). Cardiac output, cardiopulmonary volume and systemic resistance were assessed by radionuclide first-pass technique (technetium-99m red blood cell tagging). Total blood volume was determined by radioiodinated serum albumin, and the ratio of cardiopulmonary to total blood volume was used as an index of venous capacitance.

RESULTS

Twenty-one patients had accentuated venous pooling defined as a tilt-induced decrease in cardiopulmonary volume/total blood volume ratio > 15% from baseline or a supine ratio < 14% (normal 16% to 18%), or both. Seven of the 28 patients had autonomic insufficiency; 6 of the 7 also had venous pooling; 1 patient had autonomic insufficiency only. Neither clinical history nor changes during tilt differentiated the subgroups. Plasma catecholamine levels increased during head-up tilt in all subgroups, and differences in their increase were not significant between patients with venous pooling and those with autonomic insufficiency. However, radionuclide hemodynamic variables revealed that patients with venous pooling compensated for the decrease in stroke volume by increasing peripheral resistance, whereas patients with autonomic dysfunction did not.

CONCLUSIONS

Orthostatic hypotension in patients with supine hypertension may have multiple etiologies. Hemodynamic assessment with determination of cardiopulmonary volume and systemic vascular resistance differentiated between venous pooling and autonomic insufficiency in these patients; head-up tilt and plasma catecholamine levels did not. These findings may have important therapeutic implications.

Ratios between the abdominal circumference, head circumference, or femur length and the transverse cerebellar diameter of the growth-retarded and macrosomic fetus

The purpose of our investigation was twofold: to provide normative data for the ratios between head circumference and cerebellum, abdominal circumference and cerebellum, and femur length and cerebellum; and to evaluate the predictive accuracy of an abnormal ratio in the detection of growth retardation and macrosomia. Data on 675 women with normal gestations between 14 and 42 weeks were used to estimate reference curves for the three ratios to be evaluated. We then compared the ratios of 34 fetuses with intrauterine growth retardation and 28 macrosomic fetuses to the control group. Of the three ratios that we investigated, abdominal circumference to transverse cerebellar diameter was the most efficacious. However, the sensitivity of this ratio for the detection of intrauterine growth retardation and macrosomia was only 52.9% and 46.6%, respectively. A ratio between head circumference, abdominal circumference, or femur length and the transverse cerebellar diameter cannot reliably distinguish between normally growing fetuses and those that are growth retarded or macrosomic.

A simple arteriotomy method for microsurgical end-to-side anastomoses: technical aspects of use in training and laboratory applications

An experiment was carried out to show the patency rates of microsurgical carotid artery bypasses with femoral artery grafts, using a single-cut arteriotomy in rats. A bypass was done on 127 Sprague-Dawley rats. Of these, 125 were patent after 20 min, and all of these were patent after the animals were sacrificed at 3 days, for a 98 percent patency rate. The method of performing the arteriotomies, as well as the bypass itself, is described. The benefits of using the end-to-side anastomosis are explained. The authors conclude that the single-cut arteriotomy is convenient and easy to perform. The end-to-side anastomosis is a worthwhile technique and should encourage the proficiency of every student of microsurgery.

Fetal heart circumference as a predictor of menstrual age in fetuses affected by disturbances in growth

OBJECTIVE

The purpose of this study was twofold: (1) to evaluate the relationship between fetal heart circumference and gestational age and (2) to determine the effect, if any, of disturbances in fetal growth on heart circumference.

STUDY DESIGN

Heart circumference was measured in 262 women with normal gestations (control group) and in two study groups consisting of 52 large-for-gestational age 32 small-for-gestational age fetuses. Standardized, gestational age-adjusted values in the two study groups were compared with normative data provided by the control group.

RESULTS

There was a close correlation (R2 = 0.94) between heart circumference and gestational age in normally growing fetuses. Disturbances of fetal growth (i.e., macrosomia and growth retardation) were found to have an inconsistent effect on heart circumference.

CONCLUSION

Heart circumference cannot be used as an independent parameter for gestational age evaluation in fetuses with disturbances of growth.

Decision rules for the use of radiography in acute ankle injuries. Refinement and prospective validation

OBJECTIVE

To validate and refine previously derived clinical decision rules that aid the efficient use of radiography in acute ankle injuries.

DESIGN

Survey prospectively administered in two stages: validation and refinement of the original rules (first stage) and validation of the refined rules (second stage).

SETTING

Emergency departments of two university hospitals.

PATIENTS

Convenience sample of adults with acute ankle injuries: 1032 of 1130 eligible patients in the first stage and 453 of 530 eligible patients in the second stage.

MAIN OUTCOME MEASURES

Attending emergency physicians assessed each patient for standardized clinical variables and classified the need for radiography according to the original (first stage) and the refined (second stage) decision rules. The decision rules were assessed for their ability to correctly identify the criterion standard of fractures on ankle and foot radiographic series. The original decision rules were refined by univariate and recursive partitioning analyses.

MAIN RESULTS

In the first stage, the original decision rules were found to have sensitivities of 1.0 (95% confidence interval [CI], 0.97 to 1.0) for detecting 121 maleolar zone fractures, and 0.98 (95% CI, 0.88 to 1.0) for detecting 49 midfoot zone fractures. For interpretation of the rules in 116 patients, kappa values were 0.56 for the ankle series rule and 0.69 for the foot series rule. Recursive partitioning of 20 predictor variables yielded refined decision rules for ankle and foot radiographic series. In the second stage, the refined rules proved to have sensitivities of 1.0 (95% CI, 0.93 to 1.0) for 50 malleolar zone fractures, and 1.0 (95% CI, 0.83 to 1.0) for 19 midfoot zone fractures. The potential reduction in radiography is estimated to be 34% for the ankle series and 30% for the foot series. The probability of fracture, if the corresponding decision rule were "negative," is estimated to be 0% (95% CI, 0% to 0.8%) in the ankle series, and 0% (95% CI, 0% to 0.4%) in the foot series.

CONCLUSION

Refinement and validation have shown the Ottawa ankle rules to be 100% sensitive for fractures, to be reliable, and to have the potential to allow physicians to safely reduce the number of radiographs ordered in patients with ankle injuries by one third. Field trials will assess the feasibility of implementing these rules into clinical practice.

Sensitivity and specificity of the tilt table test in young patients with unexplained syncope

The usefulness of the head-up tilt testing (HUT) has been previously addressed in diagnosing vasovagal neuroregulatory syncope in the teenage population. However, data concerning sensitivity and specificity is deficient due to the lack of control groups. We compared the response to HUT in young patients referred because of syncope or near syncope (n = 44, mean age 16 +/- 3 years SD) to healthy young volunteers with a normal physical examination and no previous history of syncope (n = 18, mean age 16 +/- 2 years) and to determine the sensitivity and specificity of HUT. The graded tilt protocol was performed at 15 degrees, 30 degrees, and 45 degrees (each for 2 min), and then 60 degrees for 20 minutes. Cuff blood pressure was measured every minute and lead II ECG was continuously monitored.

RESULTS

25 of the 44 patients (57%) developed a vasovagal response or became symptomatic after 13.8 +/- 5.7 minutes of HUT. Three of the 18 volunteers (17%) had a vasovagal response and became symptomatic after 9 +/- 3 minutes of HUT. There was no statistical difference among the four groups (with and without tilt induced vasovagal response) in terms of age and baseline hemodynamic data. The sensitivity of 20 minutes HUT was 57% and its specificity was 83%. The presyncopal hemodynamic response in patients with history of syncope that was characterized by a significant decrease in systolic blood pressure and lack of increase of diastolic blood pressure as compared with baseline and with other groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiac arrest in Ontario: circumstances, community response, role of prehospital defibrillation and predictors of survival

OBJECTIVES

To describe the patient characteristics, circumstances and community response in cases of out-of-hospital cardiac arrest; to evaluate the effect on survival of the introduction of prehospital defibrillation; and to identify factors that predict survival.

DESIGN

Population-based before-and-after clinical trial.

SETTING

Five Ontario communities: London, Sudbury, the Greater Niagara region, Kingston and Ottawa.

PATIENTS

A consecutive sample of 1510 primary cardiac arrest patients who were transported to hospital by ambulance over 2 years.

INTERVENTION

The use of defibrillators by ambulance attendants.

MAIN OUTCOME MEASURES

Patient characteristics (sex and age), circumstances of arrest (place, whether arrest was witnessed and cardiac rhythm), citizen response (whether cardiopulmonary resuscitation [CPR] was started by a bystander, time to access to emergency medical services and time to initiation of CPR), emergency medical services response (ambulance response time, time to initiation of CPR and time to rhythm analysis with defibrillator) and survival rates.

MAIN RESULTS

A total of 92.1% of the patients were 50 years of age or older, and 68.3% were men. Overall, 79.6% of the arrests occurred in the home. The average ambulance response time for witnessed cases was 7.8 minutes. The overall survival rate was 2.5%. The survival rates before and after defibrillators were introduced were similar, and the general functional outcome of the survivors did not differ significantly between the two phases. Factors predicting survival included patient's age, ambulance response time and whether CPR was started before the ambulance arrived.

CONCLUSIONS

The survival rate was lower than expected. The availability of prehospital defibrillation did not affect survival. To improve survival rates after cardiac arrest ambulance response times must be reduced and the frequency of bystander-initiated CPR increased. Once these changes are in place a beneficial effect from advanced manoeuvres such as prehospital defibrillation may be seen.

Effect of atrioventricular synchrony on stroke volume during ventricular tachycardia in man

The hemodynamic consequences of atrioventricular (AV) synchrony during ventricular tachycardia were evaluated during cardiac electrophysiologic testing. The relationship between stroke volume and the AV interval was investigated on a beat-by-beat basis in six patients during induced monomorphic ventricular tachycardia. Stroke volume was calculated either (1) in the right ventricle using impedance catheter method (four patients) or (2) in the left ventricle using Doppler measurement of aortic blood velocity (two patients). The impedance catheter method underestimated stroke volume by a factor of 4.2 +/- 2.4 compared with the thermodilution cardiac output method. However, there was a highly linear relationship between both methods for computing stroke volume (r greater than 0.9). Five patients had complete AV dissociation during ventricular tachycardia, and different AV intervals spanned the entire tachycardia cycle lengths. Largest stroke volumes were associated with optimal AV intervals within 120 and 230 msec, resulting in a 97 +/- 59% increase in stroke volume over ventricular tachycardia cycles not associated with atrial activity. Customized atrial pacing during ventricular tachycardia may provide a valuable means for artificially establishing the hemodynamically optimal AV interval and eliminating the ventricular tachycardia cycles not preceded by atrial activity.

Automatic implantable cardioverter-defibrillator implantation without thoracotomy using an endocardial and submuscular patch system

The automatic cardioverter-defibrillator lead system is implanted by a thoracotomy procedure that may result in atelectasis, pleural effusion, cardiac tamponade and lengthy convalescence. A new defibrillator lead system that allows selection of different defibrillating current pathways is implanted without a thoracotomy. Ten patients requiring a cardioverter-defibrillator for recurrent sustained ventricular tachycardia (five patients) or aborted sudden cardiac death (five patients) were evaluated for implantation of this lead system. A lead configuration with a bidirectional defibrillating current pathway was implanted in nine patients. The defibrillation threshold with this lead configuration was 15 J in five patients, 20 J in three and 30 to 35 J in one patient. In the remaining patient the lead system had a 40 J defibrillation threshold and was not implanted. No perioperative complications occurred. Induced ventricular fibrillation was successfully terminated at the predischarge and intermediate follow-up (8 to 12 weeks) electrophysiologic studies. During the follow-up period, there were three deaths (one sudden, two due to heart failure) and two lead system failures (oversensing with inappropriate shocks in one patient and patch lead fracture in another). Implantation of the cardioverter-defibrillator lead system by a nonthoracotomy approach is feasible, has no significant perioperative complications and is well tolerated by patients. Effective defibrillation was demonstrated immediately as well as at intermediate follow-up study. The occurrence of patch lead fracture and oversensing requires improvement in the present (nonthoracotomy) lead system technology.

Clinical performance of the implantable cardioverter defibrillator: electrocardiographic documentation of 101 spontaneous discharges

Records of 105 patients, who received an automatic implantable cardioverter defibrillator (AICD), were studied to investigate the causes of spontaneous AICD discharges and to correlate the symptoms with the arrhythmias triggering AICD discharges. During a follow-up period of 13 +/- 8 months, 46/105 (44%) patients had 566 spontaneous AICD discharges. A total of 101 discharges were documented with Holter monitoring in 23 patients. In this study group, there were 8 (8%) AICD discharges for 5 episodes of ventricular fibrillation, and 68 (67%) discharges for 63 episodes of sustained ventricular tachycardia. Patients lost consciousness in all episodes of ventricular fibrillation, but were symptomatic prior to only 36 (53%) discharges in ventricular tachycardia. Nonsustained ventricular tachycardia persisting for a period of 7.5 +/- 2 seconds resulted in 20 AICD discharges; patients were symptomatic prior to 13 (65%) discharges. Supraventricular tachycardias triggered three discharges. One patient had two spurious discharges during sinus rhythm. In conclusion, most of the spontaneous AICD discharges were appropriate for the detected rhythms, but only clinically appropriate for the management of arrhythmias in 75% of the cases. A significant portion of the patients with sustained or nonsustained ventricular tachycardias triggering AICD discharges were asymptomatic prior to discharge, which requires further assessment of the physiology of the arrhythmia as a component of the detection algorithm.

The effects of percutaneous catheter ablation on preexisting permanent pacemakers

STUDY OBJECTIVE

Determine the effect of percutaneous catheter ablation (CA) on permanent pacemakers.

MEASUREMENTS AND RESULTS

Twenty-three patients who underwent CA at The Cleveland Clinic Foundation from September 1983 to January 1990, and had a previously implanted pacemaker were studied. Electrocardiographic data during the CA procedure and clinic data including pacemaker evaluations were analyzed. Fifty-two percent (12/23) of the pacemakers malfunctioned: five developed transient ventricular loss of capture; two undersensing; one oversensing; three could not be interrogated or programmed, and one did not respond to the magnet test. Four patients developed syncopal episodes and two severe dizziness after the procedure. All had their pacemakers replaced. In total, seven were explanted. Destructive analysis by the individual manufacturer identified pacemaker circuitry failure in five. Unipolar pacemakers and anodal ablation procedures had more frequent and severe malfunctions, but the difference was not statistically significant.

CONCLUSIONS

Pacemaker malfunction is frequent during CA. It may be prevented by programming the pacemaker, when possible, to the nonfunctioning mode (000 mode). Temporarily disconnecting the pacemaker during ablation requires further evaluation as an alternative approach. Close follow-up can detect pacemaker malfunction and prevent complications.

Infections in implantable cardioverter defibrillator patients

Implantable cardioverter defibrillators (ICDs) have been documented as an effective modality in reducing arrhythmic mortality. A serious complication associated with implantation of the device is infection. Few studies have addressed this issue. Two hundred seven patients with refractory ventricular arrhythmias underwent 207 ICD implantations, and 56 subcutaneous generator changes at our institution. Eight patients developed wound infections, four following ICD implantation (4 out of 207 or 1.9%), and four following a generator change (4 out of 56 or 7.1%). Wound cultures most commonly revealed Staphylococcus aureus and Staphylococcus epidermidis. Infections treated with antibiotics alone, or with only generator removal, frequently recurred (four out of five attempts). There were no recurrences following total patch/lead and generator system removal. In five patients, the same generator unit was successfully reimplanted following ethylene oxide sterilization without infection recurrence. We conclude that treatment of device-associated infection generally requires total generator and patch/lead system removal, and that generator units can be successfully reimplanted yielding substantial cost savings.