The expression of positive and negative schizotypy in daily life: an experience sampling study.

BACKGROUND: Psychometrically identified positive schizotypy and negative schizotypy are differentially related to psychopathology, personality and social functioning. However, little is known about the experience and expression of schizotypy in daily life and the psychological mechanisms that trigger psychotic-like experiences. METHOD: The present study employed experience sampling methodology (ESM) to assess positive and negative schizotypy in daily life in a non-clinical sample of 412 young adults. ESM is a structured diary technique in which participants are prompted at random times during the day to complete assessments of their current experiences. RESULTS: As hypothesized, positive schizotypy was associated with increased negative affect, thought impairment, suspiciousness, negative beliefs about current activities and feelings of rejection, but not with social disinterest or decreased positive affect. Negative schizotypy, on the other hand, was associated with decreased positive affect and pleasure in daily life, increased negative affect, and decreases in social contact and interest. Both positive schizotypy and negative schizotypy were associated with the desire to be alone when with others. However, this was moderated by anxiety in positive schizotypy and by diminished positive affect in negative schizotypy. CONCLUSIONS: The results support the construct validity of a multidimensional model of schizotypy and the ecological validity of the positive and negative schizotypy dimensions. ESM appears to be a promising method for examining the daily life experiences of schizotypic individuals.

The Canadian National EMS Research Agenda: Impact and Feasibility of Implementation of Previously Generated Recommendations.

BACKGROUND: A recent mixed-methods study on the state of emergency medical services (EMS) research in Canada led to the generation of nineteen actionable recommendations. As part of the dissemination plan, a survey was distributed to EMS stakeholders to determine the anticipated impact and feasibility of implementing these recommendations in Canadian systems. METHODS: An online survey explored both the implementation impact and feasibility for each recommendation using a five-point scale. The sample consisted of participants from the Canadian National EMS Research Agenda study (published in 2013) and additional EMS research stakeholders identified through snowball sampling. Responses were analysed descriptively using median and plotted on a matrix. Participants reported any planned or ongoing initiatives related to the recommendations, and required or anticipated resources. Free text responses were analysed with simple content analysis, collated by recommendation. RESULTS: The survey was sent to 131 people, 94 (71.8%) of whom responded: 30 EMS managers/regulators (31.9%), 22 researchers (23.4%), 15 physicians (16.0%), 13 educators (13.8%), and 5 EMS providers (5.3%). Two recommendations (11%) had a median impact score of 4 (of 5) and feasibility score of 4 (of 5). Eight recommendations (42%) had an impact score of 5, with a feasibility score of 3. Nine recommendations (47%) had an impact score of 4 and a feasibility score of 3. CONCLUSIONS: For most recommendations, participants scored the anticipated impact higher than the feasibility to implement. Ongoing or planned initiatives exist pertaining to all recommendations except one. All of the recommendations will require additional resources to implement.

Can quantitative capnometry differentiate between cardiac and obstructive causes of respiratory distress?

STUDY OBJECTIVE: To determine whether quantitative measurement of end-tidal carbon dioxide (ETCO2) can differentiate between cardiac and obstructive causes of respiratory distress. DESIGN: Prospective observational study. SETTING: Emergency department (ED) of a tertiary care hospital. PATIENTS: Adult patients who presented to the ED with moderate-to-severe dyspnea. Patients were excluded if they were unable to cooperate with the performance of peak expiratory flow rate (PEFR) or ETCO2 tests, were younger than 18 years of age, or had received prehospital intervention for their respiratory distress. INTERVENTIONS: Physicians obtained an ETCO2 level and PEFR prior to ED pharmacologic intervention. A hand-held capnometer with digital read-out was used to obtain the ETCO2 level. The patient's age, sex, initial vital signs, breath sounds and medication history, the presence or absence of diaphoresis and/or orthopnea, the duration of symptoms, the chest radiograph interpretation, and final diagnosis were also recorded. MEASUREMENTS AND RESULTS: Forty-two patients were eligible for inclusion in the analysis. The mean ETCO2 level was 31.1+/-9.4 mm Hg; the mean PEFR was 161.3+/-53.1 L/min. The ETCO2 levels for pulmonary edema/congestive heart failure (CHF) patients differed significantly from those of asthma/COPD patients (27.1+/-7.8 mm Hg vs 33.4+/-9.6 mm Hg; p=0.0375). However, no single ETCO2 level was found to be a reliable predictor of diagnosis. CONCLUSION: ETCO2 levels for pulmonary edema/CHF patients differ significantly from those of asthma/COPD patients. However, no single ETCO2 level reliably differentiates between the two disease processes.

Day's integration of scatter dose with an analytical expression.

Analytical formulae have been developed to describe the scatter dose on the central axis of rectangular fields as a function of depth and field size for 60Co gamma radiation and 4 and 8 MV x rays. The basic relationship expresses the scatter-to-primary dose ratio as a function of the area-to-perimeter ratio A/P, with depth and energy dependent parameters for which analytical expressions are given. The accuracy of the total dose on and off the central axis, calculated with these formulae, is compared to that resulting from the use of Day's method with tabulated values. The differences are generally less than 1% of the total dose on the central axis.

Calculations for beam-flattening filters for high-energy x-ray machines.

A flattening filter is an important component in a medical accelerator to modify the photonbeam properties. To simplify the calculations of the flattening-filter profile, we have developed a computer program which sums primary and scatter and then makes iterations in the primary component to produce a desired total-dose profile. The program can account, to first order, for radial spectral changes by using an effective primary attenuation coefficient which varies with radius. Calculations made to model the Clinac-4 dose profiles using the measured variation of half-value layer with radius show good agreement with the measured data. It is shown that the variation of quality within the beam impairs the flatness that can be achieved over a range of depths. Since perfect flatness cannot be achieved for small and large fields with one flattening filter, one may choose a primary profile which is a compromise over a range of field sizes and depths. A compromise profile for a 4-MV beam is discussed.

Scatter dose decrement values for rectangular fields.

The scatter dose decrement value (SDV) has been studied by calculational methods for 60Co gamma and 4- and 8-MV x-ray beams of rectangular cross section. In a principal plane and inside the field, the SDV is nearly independent of field size, energy, and depth when the position of the point considered is expressed as the fractional distance to the field edge. From this, it follows that the scatter dose profiles are quite similar in planes parallel to a principal plane. A second corollary is that the SDV for an arbitrary point approximately equals the product of the two SDV values for the projected points in the principal planes. Outside the field, the SDV loses this independence of the various beam conditions, and as a consequence thereof, the "product rule" leads to errors. Mathematical expressions have been derived for the SDV inside and outside small fields. The errors resulting when these small-field formulas are used for large fields have been studied. Expressed as fractions of the total dose on the centerline, these errors are of the order of +/- 1% inside the field and +/- 2% outside.

Do pulse checks cause a significant delay in the initial defibrillation sequence?

This study was undertaken to determine if checking for a pulse between initial defibrillations causes a clinically significant delay in the administration of the defibrillations. Ten emergency department nurses and 10 emergency medicine resident physicians were timed delivering three successive defibrillations (200, 300 and 360 J) to a manikin under three randomly assigned scenarios: (1) without pulse checks; (2) with pulse checks performed by an assistant; and (3) with pulse checks performed by the participant. All participants performed the three defibrillation scenarios using three different models of defibrillators. Repeated measures analysis of variance was used to compare mean defibrillation times for the three scenarios. The mean time was 20.4 +/- 1.0 s for defibrillation without pulse checks; 20.2 +/- 1.2 s with pulse checks by an assistant and 22.0 +/- 2.0 s with pulse checks by the participant. There was a statistically significant difference between no pulse checks and pulse checks by the participant. No statistically significant difference was noted between no pulse checks and pulse checks by an assistant. We conclude that checking for a pulse does cause a statistically significant delay in the administration of defibrillations. This difference, however, is not likely to be clinically relevant.

Scatter dose for wedged fields.

The behaviour of scatter dose in 4 and 8 MV wedged x-ray beams has been studied by calculating scatter-to-primary dose ratios (SPR) and comparing these with SPR for non-wedged beams. On the central axis the SPR for wedged and non-wedged beams differ only by a few per cent, a difference which increases slightly with wedge angle and field size. In other points within the field the differences are larger but generally less than 3% of the total dose on the central axis at the same depth. The product rule for points that do not lie in a principal plane is valid within the same limits as for non-wedged beams.

Comparison of staples vs suturing for securing central venous catheters.

OBJECTIVE: To determine whether skin staples can be used to secure central venous catheters as effectively as does suturing. METHODS: A prospective, randomized trial of techniques to secure a central venous catheter was performed in a medical school human anatomy laboratory using human cadavers. Central lines were secured to the upper left thorax using either standard suture material (000 silk) or skin staples (5.7 mm x 3.8 mm). Once secured, an upward force was applied to the hub of the catheter perpendicular to the skin. The amount of force needed to break the catheter hub free of the skin was measured in kg. A total of 10 measurements were made for each of 3 methods for securing the catheters (2 sutures, 2 staples, 4 staples). In addition, the site of catheter breakage was recorded. RESULTS: Those catheter hubs secured by 2 sutures required a mean force of 3.1 +/- 0.5 kg to cause breakage, and the break always occurred at the suture. Those hubs secured by 2 staples gave way at 3.0 +/- 0.3 kg (p = NS), while those secured with 4 staples gave way at 4.5 +/- 1.4 kg (p < 0.05). Although 1 hub did break, in all other stapled cases, the break occurred at the staple. CONCLUSIONS: Based on this cadaver model, use of staples appears to be as effective as suturing for securing central venous catheters. Further studies of safety and time for placement are needed.

A comparison of demand-valve and bag-valve ventilations in a swine pneumothorax model.

OBJECTIVE: Two means of delivering artificial ventilation readily available to out-of-hospital personnel are the bag-valve (BV) and the O2-powered demand-valve (OPDV). However, use of the OPDV has been limited because of concerns that it may worsen an underlying pneumothorax. This study compared the changes in size of pneumothorax in swine ventilated with the 2 devices. METHODS: Three swine were anesthetized, intubated, and instrumented with a femoral arterial line and a pediatric Swan-Ganz catheter. A chest tube was placed, the chest was opened, and the lung parenchyma was visualized. The lung was disrupted by a single stab with a #10 scalpel; the chest was then sealed; and a pneumothorax was created by injecting 30 mL of air through the chest tube. The animals were ventilated by 12 emergency medical technicians using either BV or OPDV. After 10 minutes of ventilation, the pneumothorax volume was measured. RESULTS: When comparing final pneumothorax volumes after 10 minutes of ventilation with the 2 devices, there was no significant difference (mean +/- SD = 40.8 +/- 28.2 mL vs 52.3 +/- 23.1 mL, p = 0.286). CONCLUSION: There is no difference in final pneumothorax volumes after OPDV or BV ventilation.

Study of the teratogenic potential of FD & C Yellow No. 5 when given by gavage to rats.

FD & C Yellow No. 5 (tartrazine) was given to Osborne-Mendel rats by gavage at dose levels of 0, 60, 100, 200, 400, 600 or 1000 mg/kg body weight/day on days 0-19 of gestation. No maternal or developmental toxicity was observed when the rats were killed on day 20. The mean daily food consumption for the entire period of gestation was significantly greater in the females given 1000 mg/kg body weight/day than in the controls, but maternal body-weight gain was not affected. No dose-related effects were observed in implantations, foetal viability or external foetal development. Foetal skeletal and visceral development was similar among foetuses from all groups. At the doses given, FD & C Yellow No. 5 was neither toxic nor teratogenic.

Study of the teratogenic potential of gum arabic.

Gum arabic in the diet at 0, 1, 2, 4, 7.5 or 15% was available ad lib. to male and female Osborne-Mendel rats during premating and mating and throughout gestation. During gestation, the treated females consumed from 683 mg gum/kg body weight/day in the 1% group to 10,647 mg gum/kg/day in the 15% group. The animals were killed on gestation day 20. There were no dose-related changes in maternal findings, number of foetuses, foetal viability or external, visceral or skeletal variations. No terata were seen.

Study of the teratogenic potential of FD & C Red No. 40 when given by gavage to rats.

Osborne-Mendel rats were intubated with FD & C Red No. 40 at dose levels of 0, 30, 75, 150, 300, 600, or 1000 mg/kg body weight/day on days 0-19 of gestation. No developmental toxicity was observed when the animals were killed on day 20 of gestation. No dose-related changes were seen in maternal daily observations, food consumption, body-weight gain or implantations, or in foetal viability, body weight, body length, sex distribution or external variations. Skeletal and soft-tissue development appeared similar in foetuses of all groups. The isolated increases that occurred in the number of male foetuses, number of females with two or more resorptions, number of litters with three or more sternebral variations and incidence of 14th rib bud are considered random occurrences and were not related to dosage.

The Autosow raised miniature swine as a model for assessing the effects of dietary soy trypsin inhibitor.

Toxicological effects of dietary soy trypsin inhibitor (TI) were assessed in male miniature swine, a model chosen for its similarities to human digestive physiology and anatomy. The TI preparation was extracted from defatted raw soy flour. From 1 through 5 weeks of age, piglets were automatically fed either a TI liquid diet [Autosow TI group (ASTI)] or a control liquid diet [Autosow control group (ASC)]. From 6 to 39 weeks of age, these animals received either swine chow and TI or swine chow and control article. The TI diets were formulated to contain a TI activity of approximately 500 mg TI/100 g dry matter. A sow control (SC) group suckled from birth to 6 weeks of age and then fed as the ASC group with swine chow plus control article from 6 to 39 weeks of age. The SC piglets grew faster than ASC piglets during postnatal weeks 1 and 2; however, the ASC piglets were significantly heavier than the SC piglets (P=0.001) at 6 weeks of age. Compared with the ASC group, TI caused a moderate decrease in feed consumption and a moderate but reversible decrease in growth from 2 to 5 weeks of age, but not thereafter. Some control and TI-fed Autosow-reared piglets had loose stools until 6 weeks of age; the effect was significantly greater in the TI-fed group. Otherwise, all swine were active and had normal appearance and behavior.

Pathological evaluation, clinical chemistry and plasma cholecystokinin in neonatal and young miniature swine fed soy trypsin inhibitor from 1 to 39 weeks of age.

The potential toxicity of dietary soy trypsin inhibitor (TI) was evaluated in neonatal miniature swine. From 1 to 6 weeks of age, two groups of male piglets were artificially reared in an Autosow and automatically fed either TI or control liquid diet. From 6 to 39 weeks of age, these two groups were fed either TI or control chow diet. A third group, sow control (SC), suckled from birth to 6 weeks of age, were also weaned to control chow from 6 to 39 weeks of age. Clinical chemistry and plasma cholecystokinin (CCK) determined at 6, 18, 30 and 39 weeks of age, and serum amylase activity with gross and histopathological analyses of major organs at 6 and 39 weeks of age are reported. TI had no effect on plasma CCK, serum amylase activity, or numerous clinical chemistry values. TI-fed piglets had a larger relative liver weight at 6 weeks of age. Relative pancreas weight decreased with age but was not affected by TI. Gross and histopathological analyses of major organs, except the spleen, were within normal limits. Increased incidence of extramedullary hematopoiesis was noted in the spleen of the TI group at 6 but not at 39 weeks of age. There was no consistent pattern in immunohistochemical foci for secretin, gastrin releasing polypeptide or CCK, and no change in DNA, RNA, mitotic index or nuclear density of pancreatic cells. At 6 weeks of age, TI increased pancreatic protein and amylase activity but not trypsin or chymotrypsin activity. None of the effects suggested that this dose of TI was toxic to either the neonatal or sexually mature miniature male swine.

Do pulse checks delay semiautomatic defibrillation by EMT-defibrillators?

Advanced cardiac life support (ACLS) guidelines from the American Heart Association (AHA) now recommend not checking for a pulse between the initial three defibrillations for pulseless patients in ventricular tachycardia or fibrillation. The AHA asserts that checking for a pulse needlessly delays defibrillation. This study was undertaken to determine if pulse checks delay defibrillation by EMT-Defibrillators (EMT-Ds) using a semiautomatic defibrillator (SAED). Twenty-seven EMT-Ds demonstrated delivery of three successive defibrillations during two test scenarios: once with and once without pulse checks after the first and second defibrillations. The time from the first to third defibrillation was recorded. The mean time to deliver the defibrillations was 60.2 +/- 6.2 seconds with pulse checks and 57.5 +/- 4.6 seconds without pulse checks. The difference, 2.7 +/- 5.9 seconds, was statistically significant (P = 0.026). Pulse checks by EMT-Ds do delay administration of defibrillations, but consideration should be given to reinstating pulse checks as a part of the AHA guidelines, since this delay is of questionable clinical significance.

Public perceptions of a rural emergency medical services system.

INTRODUCTION: To determine the awareness of citizens and physicians concerning the capabilities of a rural emergency medical services (EMS) system. HYPOTHESIS: Citizens and physicians are unaware of the capabilities of the EMS system. METHODS: Residents were selected randomly from the local telephone directory and asked a series of structured questions about their EMS agency. A written survey was distributed to area physicians. Chi-square analysis was used to compare the proportion of respondents who knew the available interventions in their community with the proportion of those who did not. Statistical significance was inferred at p < 0.01. RESULTS: A total of 49% of the citizens were able to identify available skills, and 41.4% of the physicians were able to identify available skills. Physicians were less likely than were the citizens to be able to identify the skills performed by each provider (p < 0.001). CONCLUSION: This study indicates that both physicians and the lay public have little understanding of the capabilities of their EMS system.

Mistaken identity: the effect of badges on EMT recognition.

INTRODUCTION: Many emergency medical services (EMS) providers wear badges with their uniforms. This study was undertaken to determine whether emergency medical technicians (EMTs) who wear badges with their uniforms are more likely to be mistaken for law enforcement personnel than are those who do not wear badges. HYPOTHESIS: Emergency medical services providers who wear badges are more likely to be mistaken for law enforcement personnel than are those who do not wear badges. METHODS: High school students, college students, civic organizations, and church groups were shown slides of different uniforms and badges/insignia and asked to identify the person portrayed. Responses were categorized as "EMS," "law enforcement," or "other." Frequency of responses for each uniform and insignia were compared with chi-square analysis. RESULTS: Fifty-nine percent of the uniforms with badges were identified as law enforcement personnel. Only 5.5% of the uniforms with badges were identified as "EMS," compared with 74% of the uniforms with a Star of Life (p < 0.001). CONCLUSION: Individuals wearing uniforms with badges are more likely to be identified as law enforcement personnel than are EMS personnel. Emergency medical services providers who do not wish to be mistaken for law enforcement personnel should wear the Star of Life, not a badge, with their uniform.

Does the ambulance environment adversely affect the ability to perform oral endotracheal intubation?

OBJECTIVE: Oral endotracheal intubation (ETI) is the preferred method of controlling the airway in critically ill or injured patients. It was postulated that time could be saved if intubation was performed in the ambulance en route to the hospital. This study was designed to determine whether the ambulance environment adversely affected the ability of emergency medical technicians at the advanced-intermediate level (EMT-AI) to perform oral ETI. HYPOTHESIS: The restrictive environment of a moving ambulance would affect adversely the ability of EMT-AIs to perform ETI compared with a controlled setting. This would result in a significant increase in the time necessary to perform ETI in the ambulance compared with a controlled setting not complicated by restrictive space and motion. METHODS: Twenty on-duty EMT-AIs were recruited to volunteer for this prospective, nonrandomized, nonblinded trial. All participants performed three consecutive oral ETIs on an airway mannequin in two settings: 1) in the back of a moving ambulance; and 2) on a table in the rescue squad station. Of the participants, 10 performed the intubations in the ambulance first; the remainder performed the intubations at the station first. Time for intubation with the mannequin was recorded by stopwatch. The mean times for intubation in both settings were compared by Student's t-test (p < 0.05). RESULTS: All intubation attempts were successful. The mean time for intubation in the station was 13.0 +/- 3.4 seconds. The mean time in the ambulance setting was 13.2 +/- 5.3 seconds. There was no significant difference between the intubation times in the two settings (p = 0.88). CONCLUSION: The environment of a moving ambulance does not appear to hinder the ability of EMT-AIs to perform oral ETI in a laboratory setting with a mannequin model.

Does ambulance crew size affect on-scene time or number of prehospital interventions?

INTRODUCTION: While large cities typically staff ambulances with two emergency medical services (EMS) professionals, some EMS agencies use three people for ambulance crews. The Greenville, North Carolina, EMS agency converted from three-person to two-person EMS crews in July 1993. There are no published reports investigating the best crew size for out-of-hospital emergency care. HYPOTHESIS: Two-person EMS crews perform the same number and types of interventions as three-person EMS crews. Two-person EMS crews do not have longer on-scene times than do three-person EMS crews. METHODS: Data for the two most common advanced life support calls in this system--seizures and chest pains--were collected for the months of June and August 1993. Three-person EMS crews responded to both types of calls in June. In August, two-person EMS crews responded to seizure calls; two-person EMS crews accompanied by a fire department engine (pumper) with additional manpower responded to chest pain calls. The frequency of specific interventions, number of total interventions, and scene times for the August calls were compared to their historical control groups, the June calls. RESULTS: One hundred twenty-six patient contacts were included in the study. There were no significant differences in total number or types of procedures performed for the two patient groups. Mean on-scene time for patients with seizures was 11.0 +/- 4.2 minutes for three-person crews and 19.4 +/- 8.3 minutes for two-person crews (p < 0.001). Mean on-scene time for patients with chest pain was 13.6 +/- 4.9 minutes for three-person crews, and 15.4 +/- 3.2 minutes for two-person crews assisted by fire department personnel (p > 0.05). CONCLUSION: Two-person EMS crews perform the same number of procedures as do three-person EMS crews. However, without the assistance of additional responders, two-person EMS crews may have statistically significantly longer on-scene times than three-person EMS crews.