Reduction in IV t-PA door to needle times using an Acute Stroke Triage Pathway.

OBJECTIVE: To determine the effectiveness of an Acute Stroke Triage Pathway in reducing door to needle times in acute stroke treatment with IV t-PA. BACKGROUND: A previous study at our tertiary referral centre, examining IV t-PA door to needle times, was completed in 2000. The median door to needle time was beyond the recommended National Institute for Neurological Disorders and Stroke (NINDS) standard of 60 minutes. In November 2001, an Acute Stroke Triage Pathway was introduced in the emergency room (ER) to address this issue. The goal of this pathway was to rapidly identify patients eligible for treatment for IV t-PA, so that CT scans and lab studies could be arranged immediately upon ER arrival. Our hypothesis was that the Triage Pathway would shorten door to CT and door to needle times. DESIGN/METHODS: Using retrospective data, pre (n=87) and post (n=47) triage pathway times were compared. The door to CT time was reduced by 11 minutes (p=0.015) and door to needle time was reduced by 18 minutes (p=0.0036) in a subgroup of patients that presented directly to our hospital. CONCLUSIONS: These results indicate that the Acute Stroke Triage Pathway is effective in reducing Door to CT and Door to Needle Times in patients presenting directly to our ER. However, a majority of treatment times were still beyond NINDS recommendations. Stroke Centers require periodic review of their efficiency to ensure that target times are being obtained and may benefit from the use of an Acute Stroke Triage Pathway.

Foot temperature in diabetic polyneuropathy: innocent bystander or unrecognized accomplice?

AIM: To explore mechanisms by which temperature could influence the pathogenesis and symptoms of diabetic polyneuropathy. METHODS: We conducted a literature review attempting to identify mechanisms by which diabetic polyneuropathy could be affected by temperature. RESULTS: Cooling can theoretically hasten the progression of diabetic polyneuropathy through several different mechanisms. Specifically, cooling can enhance neuronal ischaemia, increase formation of reactive oxygen species, slow axonal transport, increase protein kinase C activity, and interfere with immune function. Short-term temperature fluctuations (both warming and cooling) can initiate and exacerbate neuropathic pain by causing neuronal hyperexcitability and functional deafferentation. Although normal fluctuations of distal extremity temperature may be sufficient for these effects, impaired thermoregulation may make the distal extremities more susceptible to temperature extremes. Eventually, a 'vicious cycle' may ensue, resulting in neuronal deterioration with further disruption of temperature regulation. Limited epidemiological data suggest a higher prevalence of diabetic polyneuropathy in populations living in colder locations, supporting our hypothesis. CONCLUSIONS: Variations in foot temperature may play an important but as yet unrecognized role in the development and symptoms of diabetic polyneuropathy. Further basic and clinical research exploring this concept could help elucidate the natural history of diabetic polyneuropathy and lead to novel therapeutic strategies.

Low rate of complications of cerebral angiography in routine clinical practice.

OBJECTIVE: The use of cerebral angiography (ANGIO) to select patients for carotid endarterectomy (CEA) has been limited by concern about the risk of complications of the procedure. The authors sought to determine the rate of neurologic complications at both an academic medical center (AMC) and a community hospital (CH). METHODS: The authors reviewed the records of 569 patients undergoing ANGIO. Any documentation of stroke, transient neurologic event, myocardial infarction, or death occurring in the 24 hours after the procedure was recorded. The rate of neurologic complications at the AMC and CH were compared to published studies. RESULTS: The overall complication rate was 0.5% for stroke and 0.4% for TIA. There was no difference between the AMC and CH. One of the strokes was of moderate severity and four of the five patients with complications subsequently underwent endarterectomy. CONCLUSIONS: The rate of major neurologic complications due to ANGIO may be lower than expected, even when performed in a non-academic setting. Awareness of local ANGIO complication rates is important when selecting patients for CEA.

Intravenous tissue plasminogen activator for acute ischemic stroke: A Canadian hospital's experience.

BACKGROUND AND PURPOSE: In the United States, tissue plasminogen activator (tPA) was approved for treatment of acute ischemic stroke in 1996. Its use has only recently been approved in Canada. We sought to evaluate the safety, feasibility, and efficacy of treatment in a Canadian hospital setting. METHODS: A combined retrospective and prospective review is presented of 46 consecutive patients treated with intravenous tPA at our hospital with a treatment protocol similar to that of the National Institute of Neurological Disorders and Stroke (NINDS) trial. RESULTS: Symptomatic intracranial hemorrhage at 36 hours occurred in 1 patient (2.2%). The median time to treat was 165 minutes, with a median "door-to-needle" time of 84 minutes. Compared with patients presenting initially at our hospital, patients transferred from another institution for tPA therapy were treated closer to the 3-hour time window (mean 173 versus 148 minutes, P:<0.001) but had a shorter door-to-needle time (43 versus 102 minutes, P:<0.001). For every 10 minutes closer to the 3-hour time window that any patient arrived at the hospital, 7 minutes was saved in the door-to-needle time (correlation coefficient 0.9, P:<0.001). Patient outcome did not differ from that in the NINDS trial (P:>0.75). CONCLUSIONS: Our safety and patient outcome data compare favorably with NINDS and Phase IV data. Although a 3-hour treatment window was feasible, the median door-to-needle time lengthened as more treatment time was available and the door-to-needle time was beyond recommended standards. This review has prompted changes in our community to improve treatment efficiency.

COPD: using nutrition to prevent respiratory function decline.

Close to three-fourths of patients with chronic obstructive pulmonary disease (COPD) suffer from weight loss. Identifying a single cause for this is difficult, as several factors-including chronic mouth breathing, dyspnea, aerophagia, certain medications, and depression-often act in concert. Malnutrition can exacerbate symptoms of COPD by decreasing ventilatory muscle strength, exercise tolerance, and immunocompetence, and by increasing the risk of depression and anxiety. Goals of nutrition intervention are to prevent or reverse malnutrition without worsening the disease process and to improve respiratory function, thereby reducing morbidity and delaying mortality. Recommendations for intake of fats, carbohydrates, protein, and water must be individualized.

Longitudinal assessment of the nutritional status of elderly veterans.

Elderly persons are at risk for developing malnutrition due to a number of age-related factors, and conversely, malnutrition can worsen declining physiological and psychosocial conditions. The purpose of this study was to determine the nutritional status of an elderly, ambulatory outpatient population, and to evaluate change in nutritional status over a 2-year period. The 209 subjects were male veterans, over 65 years of age without acute disease-related nutritional risk factors. Nutrient intake was determined through food recalls and food frequency questionnaires. Anthropometrics included circumferences and skinfolds. Laboratory measures included selected minerals and vitamins, as well as hematological and lipid profiles. Mean intake of nutrients generally met or exceeded the Recommended Dietary Allowances with the exception of calories, although > 25% of subjects consumed inadequate amounts of thiamine, vitamin A, vitamin C, and calcium. Few subjects were found to be extremely underweight or obese, although skinfolds decreased over the two years. Mean laboratory measures were within normal range with the exception of selenium, cholesterol, and low density lipoprotein. Dietary, biochemical, and anthropometric data indicate good nutritional status in general, although dietary vitamin C, vitamin A, and calcium may be poor in subgroups; body fat as assessed by skinfolds appeared to decline; and selenium, lipid profiles, and hematological profiles warrant further investigation.

Factors influencing dairy calcium intake in women.

OBJECTIVES: Most national dietary studies have reported inadequate calcium (Ca) intake by women, indicating that marketing and educational efforts have not effected dietary behavior changes. The purpose of this study was to identify knowledge, attitudes, and behaviors which influence dairy Ca intake. METHODS: A questionnaire was developed to accomplish these objectives, and piloted for clarity and content validity. Dietary Ca intake was assessed using a food frequency questionnaire. After revisions, women were sampled from four sources: a health spa, elderhostel classes, through a Cooperative Extension Service program, and from the Illinois Older Women's League. The response rate was 66.5%. RESULTS: Mean total reported Ca intake (n = 351) was 591 +/- 355 mg/day. Over 40% of the women reported Ca intakes below 60% of the RDA and could therefore be considered to have deficient intake. Unfortunately, 27.1% of these with deficient intake believed they were meeting the Ca RDA. Significant differences (p < or = 0.01) were found in attitudes and beliefs about dairy Ca when comparing women whose intake was below 60% of the RDA with those whose intake was above 60%. The most commonly mentioned beliefs of the entire sample concerned cholesterol (16.5%), high calories (13.7%) and gastrointestinal discomfort (12.8%). CONCLUSIONS: These findings suggest an important discrepancy between perceived and actual Ca intake which could influence receptiveness to education. Non-dairy Ca rich food sources need to be clarified as does the caloric and cholesterol content of dairy foods.

Loss of appetite: managing unwanted weight loss in the older patient.

Loss of appetite, regardless of cause, is a significant symptom that may cause extreme weight loss in older patients. The consequences of anorexia include muscle wasting, weakness, depression, increased susceptibility to disease complications, and decreased immunocompetence. In the older population, the major causes of anorexia are pulmonary and cardiac diseases, cancer, dementia, alcoholism, depression, and medications. The diagnosis is based on the physical exam, a history of weight loss, and a review of dietary intake. Treatment strategies include managing GI disturbances, encouraging physical activity and socialization, reducing fatigue and food aversions, and adding high-calorie supplements to the diet.

Depression of plasma cholesterol in men by consumption of baked products containing soy protein.

The effects of soy-protein consumption with and without soy fiber on plasma lipids in 26 mildly hypercholesterolemic men were studied. Four, 4-wk dietary treatments included 50 g protein and 20 g dietary fiber from soy flour (SF), isolated soy protein/soy cotyledon fiber (ISP/SCF), ISP/cellulose (ISP/C), or nonfat dry milk/C (NFDM/C) in conjunction with a low-fat, low-cholesterol diet. Plasma total cholesterol (TC) concentrations were lowest for both ISP dietary treatments compared with baseline (P < 0.05) and NFDM/C (P < 0.01). SF also led to lower TC compared with NFDM/C (P < 0.05). LDL-cholesterol values were lowest for both ISP treatments compared with NFDM/C (P < 0.01), but lower compared with baseline only with ISP/SCF (P < 0.05). Apolipoprotein B was lowest when ISP/C was fed, compared with baseline, SF, and NFDM (P < 0.05). HDL-cholesterol and total triglycerides (TG) were not affected. Results indicate that 50 g ISP is effective in lowering TC, LDL-C, and apolipoprotein B while maintaining HDL concentrations in mildly hypercholesterolemic men.

Effects of acute ethanol doses or dietary phenobarbitol with carbon tetrachloride exposure on vitamin A status of rats.

Hepatotoxins such as ethanol and CCl4 are known to adversely affect vitamin A metabolism, although the effects of acute exposure to these agents have received less evaluation. The purpose of this study was to determine the effects of vitamin A status after a series of acute ethanol doses or a series of CCl4 inhalation challenges with concurrent phenobarbital exposure in the diet of rats. The depressed hepatic vitamin A seen after one ethanol dose was not sustained after repeated dosings. However, the significantly increased urine and liver radiolabeled vitamin A recovery after three acute ethanol exposure periods suggests adaptive physiologic and metabolic changes after the initial dose. The results of repeated CCl4/phenobarbital dosings on vitamin A status paralleled, for the most part, the ethanol results. Thus, the initial acute exposure of hepatotoxic agents causes metabolic changes that are not fully sustained as the animal adapts to these challenges.

Vitamin A status of alcoholics upon admission and after two weeks of hospitalization.

The purpose of this study was to determine the vitamin A status of alcoholics upon admission and after a brief in-patient stay. Fasting blood was drawn from 28 randomly selected subjects who were presumed to represent a wide range of liver disease severity. Admission laboratory tests revealed hypozincemia in 14.8% of subjects, while serum retinol and retinol-binding protein (RBP) were depressed below normal range in 15 (57.1%) and 7 (25%) of the subjects, respectively. Significant linear correlations were found between serum retinol and RBP (r = 0.90, p < or = 0.0001), serum retinol and albumin (r = 0.76, p < or = 0.0001), serum retinol and serum zinc (r = 0.56, p < or = 0.0003), and serum retinol and serum triglycerides (r = 0.42, p < or = 0.006). All subjects with elevated serum bilirubin levels demonstrated depressed serum retinol levels. However, elevated molar ratios of retinol to RBP suggest that the carrying capacity of RBP was at times exceeded, even with low serum retinol levels. Follow-up of 12 subject after 2 weeks of hospitalization revealed significant individual changes in blood chemistry, but no general trends. Although this study emphasizes the need for individual evaluation and treatment, elevated bilirubin levels may be indicative of low serum retinol levels in the alcoholic. Caution in levels of vitamin A therapy in these cases is advised, and consideration should instead be given to beta-carotene supplementation.

Frequency domain analysis of electrotonic coupling between leech Retzius cells.

Transfer functions of the input impedance Z(f) and coupling ratio H(f) were measured from the paired Retzius cells of leech segmental ganglia, using sinusoidal and pseudorandom test test currents. The data were compared with two classes of linear electric circuit models of electrotonic coupling, one with a purely resistive junction, and the other with a finite equivalent cable coupling the two somata. Model simulations suggested the phase behavior of the coupling ratio as a sensitive discriminator between these two cases. For resistive coupling, the phase of the coupling ratio asymptotically approaches -90 degrees at high frequencies, while for a cable segment, at least 0.5 length constants in length, it crosses -90 degrees with a definite negative slope and continues to more negative values. Measured phase lags of the coupling ratio in Retzius cell preparations consistently exceeded -90 degrees at frequencies above 50 Hz, and phase plots crossed -90 degrees with significantly negative slopes. We conclude therefore that a significant cable segment contributes to the coupling between Retzius cell somata.

Strain sensitivity and directionality in cat atrial mechanoreceptors in vitro.

1. Afferent discharges from single atrial mechanoreceptors were studied in vitro in isolated, perfused cat hearts, by balloon inflation and by localized endocardial stretching with step and ramp wave forms. 2. Receptor excitability could be maintained for several hours with perfusion, but failed reversibly within a half hour without it. 3. Responses to pure step stimuli were purely phasic, adapting within a few seconds as negative fractional powers of time. Ramp responses showed corresponding behaviour; 4. Median discharge sensitivities were 12 Hz ml.-1 for step balloon inflation and 110 Hz strain-1 for step local stretching, so that 1 ml. balloon expansion was equivalent to 10% local stretch. 5. Ramp stimulation indicated two distinct receptor groups, a 'high-pass latency' (HPL) group for which threshold decreased with increasing ramp velocity, and a larger 'low-pass latency' (LPL) group with the opposite behaviour. 6. The endocardial deformation due to local stretching comprised about half simple extension and half shear, so that half the effective lineal stretch would occur in end filaments oriented within 20 degrees of the stretch axis. 7. Of five receptors tested for directionality by local stretching in two perpendicular directions, four showed significant directionality in step sensitivity and/or ramp response latency, indicating the capability of receptive fields to encode changes in endocardial shape.

Methylxanthine-induced escalation: a propagated wave phenomenon observed in skeletal muscle developing in culture.

Relatively low concentrations of methylxanthines increase spontaneous twitching in cultured muscle fibers; they also cause a second activity, escalation, which is the initiation and undiminished propagation of visible waves. The effect on twitching is abolished by depolarizing concentrations of K(+) or by tetrodotoxin; the effect on escalation is not. Escalation is prevented by removal of external Ca(++) or by the addition of tetracaine.

Extracellular crystalline material in intercellular spaces of cockroach peripheral glia.

Campaniform sensilla on legs of the cockroach, Blaberus discoidalis, are mechanoreceptors; each sensillum functions via a single bipolar neuron. The cell bodies of the bipolar neurons are tunicated; that is, they are spirally wrapped by one or more glial cells. An elaborate extracellular channel is defined by the plasma membranes of adjacent glial cell folds surrounding a given neuron. The electron microscope reveals that this extracellular space often contains conspicuous crystalline material whose lattice planes, oriented at right angles to the long crystal axis, are manifest as parallel electron-dense lines separated by an intercentre distance of 150 A. The chemical nature of these crystals has not been determined in the present study. Like most biological crystals, however, this precisely ordered crystalline material is probably proteinaceous.

The fine structure of cockroach campaniform sensilla.

Campaniform sensilla on cockroach legs provide a good model system for the study of mechanoreceptive sensory transduction. This paper describes the structure of campaniform sensilla on the cockroach tibia as revealed by light- and electron-microscopy. Campaniform sensilla are proprioceptive mechanoreceptors associated with the exoskeleton. The function of each sensillum centers around a single primary sense cell, a large bipolar neuron whose 40 micro-wide cell body is available for electrophysiological investigation with intracellular microelectrodes. Its axon travels to the central nervous system; its dendrite gives rise to a modified cilium which is associated with the cuticle. The tip of the 20 micro-long dendrite contains a basal body, from which arises a 9 + 0 connecting cilium. This cilium passes through a canal in the cuticle, and expands in diameter to become the sensory process, a membrane-limited bundle of 350-1000 parallel microtubules. The tip of the sensory process is firmly attached to a thin cap of exocuticle; mechanical depression of this cap, which probably occurs during walking movements, effectively stimulates the sensillum. The hypothesis is presented that the microtubules of the sensory process play an important role in mechanoelectric transduction in cockroach campaniform sensilla.