Do High Visibility Enforcement programs affect aggressive driving behavior? An empirical analysis using Naturalistic Driving Study data

This paper investigates the effect of High Visibility Enforcement (HVE) programs on different types of aggressive driving behavior, namely, speeding, tailgating, unsafe lane changes and 'other' aggressive driving behavior types (occurrence of not-yielding right-of-way and red light or stop signs violations). For this purpose, the Second Strategic Highway Research Program (SHRP2) Naturalistic Driving Study (NDS) data are used, which include forward-facing videos and time series information with regard to trips conducted at or near the locations of HVE implementation. To capture the intensity and duration of speeding and tailgating, scaled metrics are developed. These metrics can capture varying levels of aggressive driving behavior enabling, thus, a direct comparison of the various behavioral aspects over time and among different drivers. To identify the effect of HVE and other trip, driver, vehicle or environmental factors on speeding and tailgating, while accounting for possible interrelationship among the behavior-specific scaled metrics, Seeming Unrelated Regression Equation (SURE) models were developed. To analyze the likelihood of occurrence of unsafe lane changes and 'other' aggressive driving behavior types, a grouped random parameters ordered probit model with heterogeneity in means and a correlated grouped random parameters binary logit model were estimated, respectively. The results showed that drivers' awareness of HVE implementation has the potential to decrease aggressive driving behavior patterns, especially unsafe lane changes and 'other' aggressive driving behaviors.

Analysis of stationary and dynamic factors affecting highway accident occurrence: A dynamic correlated grouped random parameters binary logit approach

Traditional accident analysis typically explores non-time-varying (stationary) factors that affect accident occurrence on roadway segments. However, the impact of time-varying (dynamic) factors is not thoroughly investigated. This paper seeks to simultaneously identify pre-crash stationary and dynamic factors of accident occurrence, while accounting for unobserved heterogeneity. Using highly disaggregate information for the potential dynamic factors, and aggregate data for the traditional stationary elements, a dynamic binary random parameters (mixed) logit framework is employed. With this approach, the dynamic nature of weather-related, and driving- and pavement-condition information is jointly investigated with traditional roadway geometric and traffic characteristics. To additionally account for the combined effect of the dynamic and stationary factors on the accident occurrence, the developed random parameters logit framework allows for possible correlations among the random parameters. The analysis is based on crash and non-crash observations between 2011 and 2013, drawn from urban and rural highway segments in the state of Washington. The findings show that the proposed methodological framework can account for both stationary and dynamic factors affecting accident occurrence probabilities, for panel effects, for unobserved heterogeneity through the use of random parameters, and for possible correlation among the latter. The comparative evaluation among the correlated grouped random parameters, the uncorrelated random parameters logit models, and their fixed parameters logit counterpart, demonstrate the potential of the random parameters modeling, in general, and the benefits of the correlated grouped random parameters approach, specifically, in terms of statistical fit and explanatory power.

Optimal cooperative searching using purely repulsive interactions

Foraging, either solitarily or collectively, is a necessary behavior for survival that is demonstrated by many organisms. Foraging can be collectively optimized by utilizing communication between the organisms. Examples of such communication range from high level strategic foraging by animal groups to rudimentary signaling among unicellular organisms. Here we systematically study the simplest form of communication via long range repulsive interactions between multiple diffusing Brownian searchers on a one-dimensional lattice. We show that the mean first passage time for any one of them to reach a fixed target depends non-monotonically on the range of the interaction and can be optimized for a repulsive range that is comparable to the average spacing between searchers. Our results suggest that even the most rudimentary form of collective searching does in fact lower the search time for the foragers suggesting robust mechanisms for search optimization in cellular communities.

Adalimumab drug and antibody levels as predictors of clinical and laboratory response in patients with Crohn's disease

BACKGROUND

Adalimumab is an effective treatment for Crohn's disease (CD). Anti-adalimumab antibodies (AAA) and low trough serum drug concentrations have been implicated as pre-disposing factors for treatment failure.

AIMS

To assess adalimumab and AAA serum levels, and to examine their association and discriminatory ability with clinical response and serum C-reactive protein (CRP).

METHODS

We performed a cross-sectional study using trough sera from adalimumab-treated CD patients. Demographical data, Montreal classification, treatment regimen and clinical status were recorded. Serum adalimumab, AAA and CRP were measured. Receiver operating characteristic analysis and a multivariate regression model were performed to find drug and antibody thresholds for predicting disease activity at time of serum sampling.

RESULTS

One hundred and eighteen trough serum samples were included from 71 patients. High adalimumab trough serum concentration was associated with disease remission (Area Under Curve 0.748, P < 0.001). A cut-off drug level of 5.85 μg/mL yielded optimal sensitivity, specificity and positive likelihood ratio for remission prediction (68%, 70.6% and 2.3, respectively). AAA were inversely related with adalimumab drug levels (Spearman's r = -0.411, P < 0.001) and when subdivided into categorical values, positively related with disease activity (P < 0.001). High drug levels and stricturing vs. penetrating or inflammatory phenotype, but not AAA levels, independently predicted disease remission in a multivariate logistic regression model.

CONCLUSIONS

Adalimumab drug levels were inversely related to disease activity. High levels of anti-adalimumab antibodies were positively associated with disease activity, but this association was mediated mostly by adalimumab drug levels.

Does EMS perceived anatomic injury predict trauma center need?

OBJECTIVE

Our objective was to determine the predictive value of the anatomic step of the 2011 Field Triage Decision Scheme for identifying trauma center need.

METHODS

Emergency medical services (EMS) providers caring for injured adults transported to regional trauma centers in three midsized communities were interviewed over two years. Patients were included, regardless of injury severity, if they were at least 18 years old and were transported by EMS with a mechanism of injury that was an assault, motor vehicle or motorcycle crash, fall, or pedestrian or bicyclist struck. The interview was conducted upon emergency department (ED) arrival and collected physiologic condition and anatomic injury data. Patients who met the physiologic criteria were excluded. Trauma center need was defined as nonorthopedic surgery within 24 hours, intensive care unit admission, or death prior to hospital discharge. Data were analyzed by calculating descriptive statistics, including positive likelihood ratios (+LRs) with 95% confidence intervals (CIs).

RESULTS

A total of 11,892 interviews were conducted. One was excluded because of missing outcome data and 1,274 were excluded because they met the physiologic step. EMS providers identified 1,167 cases that met the anatomic criteria, of which 307 (26%) needed the resources of a trauma center (38% sensitivity, 91% specificity, +LR 4.4; CI: 3.9-4.9). Criteria with a +LR ≥5 were flail chest (9.0; CI: 4.1-19.4), paralysis (6.8; CI: 4.2-11.2), two or more long-bone fractures (6.3; CI: 4.5-8.9), and amputation (6.1; CI: 1.5-24.4). Criteria with a +LR >2 and <5 were penetrating injury (4.8; CI: 4.2-5.6) and skull fracture (4.8; CI: 3.0-7.7). Only pelvic fracture (1.9; CI: 1.3-2.9) had a +LR less than 2.

CONCLUSIONS

The anatomic step of the Field Triage Guidelines as determined by EMS providers is a reasonable tool for determining trauma center need. Use of EMS perceived pelvic fracture as an indicator for trauma center need should be reevaluated. Key words: wounds and injury; triage; emergency medical services; emergency medical technicians.

Comparison of central and intraesophageal factors between gastroesophageal reflux disease (GERD) patients and those with GERD-related noncardiac chest pain

Gastroesophageal reflux disease (GERD) causes a wide range of symptoms. Some patients present with typical symptoms such as heartburn and regurgitation and others with atypical symptoms such as chest pain. The mechanism responsible for the varying clinical presentation of GERD is still not fully elucidated. The aim of this study was to prospectively evaluate differences in central and local intraesophageal factors between patients with typical GERD symptoms and those with noncardiac chest pain (NCCP). Patients presenting with typical and atypical symptoms suspicious of GERD underwent upper endoscopy and 24-hour pH monitoring with four sensors, each positioned at a different esophageal level. All patients completed GERD symptom, Hospital Anxiety and Depression Scale, and Symptom Stress Rating questionnaires. From January 2006 to December 2009, 50 patients were recruited, 29 with typical symptoms, and 21 with NCCP. Patients with proven GERD and NCCP had higher proximal extension of acid during reflux episodes than patients with typical symptoms. They were found to be older, had a shorter history of symptom onset, worse anxiety scores, and more endoscopic findings compatible with gastritis. Proximal extension of acid during the reflux episodes in patients with GERD presenting with NCCP may play a role in symptom generation.

Comparison of central and intraesophageal factors between gastroesophageal reflux disease (GERD) patients and those with GERD-related noncardiac chest pain

Gastroesophageal reflux disease (GERD) causes a wide range of symptoms. Some patients present with typical symptoms such as heartburn and regurgitation and others with atypical symptoms such as chest pain. The mechanism responsible for the varying clinical presentation of GERD is still not fully elucidated. The aim of this study was to prospectively evaluate differences in central and local intraesophageal factors between patients with typical GERD symptoms and those with noncardiac chest pain (NCCP). Patients presenting with typical and atypical symptoms suspicious of GERD underwent upper endoscopy and 24-hour pH monitoring with four sensors, each positioned at a different esophageal level. All patients completed GERD symptom, Hospital Anxiety and Depression Scale, and Symptom Stress Rating questionnaires. From January 2006 to December 2009, 50 patients were recruited, 29 with typical symptoms, and 21 with NCCP. Patients with proven GERD and NCCP had higher proximal extension of acid during reflux episodes than patients with typical symptoms. They were found to be older, had a shorter history of symptom onset, worse anxiety scores, and more endoscopic findings compatible with gastritis. Proximal extension of acid during the reflux episodes in patients with GERD presenting with NCCP may play a role in symptom generation.

Does mechanism of injury predict trauma center need?

OBJECTIVE

To determine the predictive value of the mechanism-of-injury step of the American College of Surgeons Field Triage Decision Scheme for determining trauma center need.

METHODS

Emergency medical services (EMS) providers caring for injured adult patients transported to the regional trauma center in three midsized communities over two years were interviewed upon emergency department (ED) arrival. Included was any injured patient, regardless of injury severity. The interview collected patient physiologic condition, apparent anatomic injury, and mechanism of injury. Using the 1999 Scheme, patients who met the physiologic or anatomic steps were excluded. Patients were considered to need a trauma center if they had nonorthopedic surgery within 24 hours, had intensive care unit admission, or died prior to hospital discharge. Data were analyzed by calculating positive likelihood ratios (+LRs) and 95% confidence intervals (CIs) for each mechanism-of-injury criterion.

RESULTS

A total of 11,892 provider interviews were conducted. Of those, one was excluded because outcome data were not available, and 2,408 were excluded because they met the other steps of the Field Triage Decision Scheme. Of the remaining 9,483 cases, 2,363 met one of the mechanism-of-injury criteria, 204 (9%) of whom needed the resources of a trauma center. Criteria with a +LR ≥ 5 were death of another occupant in the same vehicle (6.8; CI: 2.7-16.7), fall >20 feet (5.3; CI: 2.4-11.4), and motor vehicle crash (MVC) extrication time >20 minutes (5.1; CI: 3.2-8.1). Criteria with a +LR between >2 and <5 were intrusion >12 inches (4.2; CI: 2.9-5.9), ejection (3.2; CI: 1.3-8.2), and deformity >20 inches (2.5; CI: 1.9-3.2). The criteria with a +LR ≤ 2 were MVC speed >40 mph (2.0; CI: 1.7-2.4), pedestrian/bicyclist struck at a speed >5 mph (1.2; CI:1.1-1.4), bicyclist/pedestrian thrown or run over (1.2; CI: 0.9-1.6), motorcycle crash at a speed >20 mph (1.2; CI: 1.1-1.4), rider separated from motorcycle (1.0; CI: 0.9-1.2), and MVC rollover (1.0; CI: 0.7-1.5).

CONCLUSION

Death of another occupant, fall distance, and extrication time were good predictors of trauma center need when a patient did not meet the anatomic or physiologic conditions. Intrusion, ejection, and vehicle deformity were moderate predictors. Key words: wounds and injury; triage; emergency medical services; emergency medical technicians; predictors; mechanism of injury; trauma center.

EMS Provider assessment of vehicle damage compared with assessment by a professional crash reconstructionist

OBJECTIVE

To determine the accuracy of emergency medical services (EMS) provider assessments of motor vehicle damage when compared with measurements made by a professional crash reconstructionist.

METHODS

EMS providers caring for adult patients injured during a motor vehicle crash and transported to the regional trauma center in a midsized community were interviewed upon emergency department arrival. The interview collected provider estimates of crash mechanism of injury. For crashes that met a preset severity threshold, the vehicle's owner was asked to consent to having a crash reconstructionist assess the vehicle. The assessment included measuring intrusion and external automobile deformity. Vehicle damage was used to calculate change in velocity. Paired t-test, correlation, and kappa were used to compare EMS estimates and investigator-derived values.

RESULTS

Ninety-one vehicles were enrolled; of these, 58 were inspected and 33 were excluded because the vehicle was not accessible. Six vehicles had multiple patients. Therefore, a total of 68 EMS estimates were compared with the inspection findings. Patients were 46% male, 28% were admitted to hospital, and 1% died. The mean EMS-estimated deformity was 18 inches and the mean measured deformity was 14 inches. The mean EMS-estimated intrusion was 5 inches and the mean measured intrusion was 4 inches. The EMS providers and the reconstructionist had 68% agreement for determination of external automobile deformity (kappa 0.26) and 88% agreement for determination of intrusion (kappa 0.27) when the 1999 American College of Surgeons Field Triage Decision Scheme criteria were applied. The mean (± standard deviation) EMS-estimated speed prior to the crash was 48 ± 13 mph and the mean reconstructionist-estimated change in velocity was 18 ± 12 mph (correlation -0.45). The EMS providers determined that 19 vehicles had rolled over, whereas the investigator identified 18 (kappa 0.96). In 55 cases, EMS and the investigator agreed on seat belt use; for the remaining 13 cases, there was disagreement (five) or the investigator was unable to make a determination (eight) (kappa 0.40).

CONCLUSIONS

This study found that EMS providers are good at estimating rollover. Vehicle intrusion, deformity, and seat belt use appear to be more difficult for EMS to estimate, with only fair agreement with the crash reconstructionist. As expected, the EMS provider -estimated speed prior to the crash does not appear to be a reasonable proxy for change in velocity.

Comparison of the 1999 and 2006 trauma triage guidelines: where do patients go?

BACKGROUND

In 2006, the Centers for Disease Control and Prevention (CDC) released a revised Field Triage Decision Scheme. It is unknown how this modified scheme will affect the number of patients identified by emergency medical services (EMS) for transport to a trauma center.

OBJECTIVES

To determine the change in the number of patients transported by EMS who meet the 2006 scheme, compared with the 1999 scheme, and to determine how the scheme change would affect under- and overtriage rates.

METHODS

The EMS providers in charge of care for injured adult patients transported to a regional trauma center in three mid-sized cities were interviewed immediately after completing transport. All injured patients were included, regardless of severity. The interview included patient demographics, vital signs, apparent anatomic injury, and the mechanism of injury. Included patients were then followed through hospital discharge. The 1999 and 2006 scheme criteria were each retrospectively applied to the collected data. The numbers of patients identified by the two schemes were determined. Patients were considered to have needed a trauma center if they had nonorthopedic surgery within 24 hours, were admitted to an intensive care unit (ICU), or died. Data were analyzed using descriptive statistics including 95% confidence intervals.

RESULTS

EMS interviews were conducted for 11,892 patients and outcome data were unavailable for one patient. The average patient age was 48 years; 51% of the patients were men. Providers reported bringing 54% of the enrolled patients to the trauma center based on their local trauma protocol. Medical record review identified 12% of the enrolled patients as needing a trauma center. Use of the 2006 scheme would have resulted in 1,423 fewer patients (12%; 95% confidence interval [CI]:11%-13%) being identified as needing a trauma center by EMS providers (40%; 95% CI: 39%-41% versus 28%; 95% CI: 27%-29%). Of those patients, 1,344 (94%) did not actually need the resources of a trauma center, whereas 78 (6%) actually needed the resources of a trauma center and would have been undertriaged.

CONCLUSION

Use of the 2006 Field Triage Decision Scheme would have resulted in a significant decrease in the number of patients identified as needing the resources of a trauma center. These changes reduced overtriage while causing a small increase in the number of patients who would have been undertriaged.

Unrecognized major bleeding following thrombolysis for acute myocardial infarction presenting with syncope

Complete atrioventricular block and syncope sometimes are the presenting signs of acute myocardial infarction. In a presyncopal attempt to assume sitting position, the patient may fall and suffer consequent trauma. Once in hospital, this sequence of events may be overlooked by both the patient and admitting physicians. Moreover, physical examination initially may not be revealing. We report on two such patients who developed massive subcutaneous bleeding following thrombolytic and heparin treatment. We conclude that these patients constitute a specific group with a relatively high risk of trauma and bleeding at the gluteal region following thrombolytic therapy. Special attention must be given to these patients.

Optimization of aeromedical base locations in New Mexico using a model that considers crash nodes and paths

In a recent paper, Tokar Erdemir et al. (2008) introduce models for service systems with service requests originating from both nodes and paths. We demonstrate how to apply and extend their approach to an aeromedical base location application, with specific focus on the state of New Mexico (NM). The current aeromedical base locations of NM are selected without considering motor vehicle crash paths. Crash paths are the roads on which crashes occur, where each road segment has a weight signifying relative crash occurrence. We analyze the loss in accident coverage and location error for current aeromedical base locations. We also provide insights on the relevance of considering crash paths when selecting aeromedical base locations. Additionally, we look briefly at some of the tradeoff issues in locating additional trauma centers vs. additional aeromedical bases in the current aeromedical system of NM. Not surprisingly, tradeoff analysis shows that by locating additional aeromedical bases, we always attain the required coverage level with a lower cost than with locating additional trauma centers.

The effect of unrestrained rear-seat passengers on driver mortality

BACKGROUND

It is well documented that seat belt usage effectively reduces the severity of motor vehicle occupant injuries and fatalities in roadway crashes. This research examines how the presence of an unrestrained rear-seat passenger seated directly behind an airbag and/or belt-restrained driver affects the driver's risk of injury in two different idealized crash scenarios. Empirical data used in the study was obtained from four sled tests conducted with various size Hybrid III crash test dummies.

METHODS

Three tests simulated a frontal (head-on) impact between two vehicles. The first established the baseline condition: a driver dummy restrained by a belt and an airbag system, with an identical belt-restrained dummy seated directly behind. The other two frontal-mode tests involved different size driver dummies restrained in the same manner, with different size unrestrained dummies behind them. A fourth test featured an angled driver-side impact crash with a restrained driver and unrestrained rear seat passenger.

RESULTS

In both of the latter cases the driver incurred a high likelihood of severe head and chest injuries relative to that inferred in the baseline exposure. The last test featured two identical dummies in a simulated lateral (driver-side) inter-vehicular impact using a belt-restrained (only) driver and an unrestrained rear-seat passenger. Driver mortality was not significantly affected in this configuration.

CONCLUSION

Unrestrained rear-seat passengers place themselves as well as their driver at great risk of serious injury when involved in a head-on crash.

Evaluating the reliability of automated collision notification systems

The use of an automated collision notification (ACN) device in vehicles can greatly reduce the time between crash occurrence and notification of emergency medical services (EMSs). Most ACN devices rely on cellular technology to report important crash information to the proper authorities. The objective of this study was to examine the ability of the existing western New York cellular analog system to support ACN systems. The first task was to develop a model predicting the probability of successfully completing an emergency ACN call at attenuated levels of received signal strength indicator (RSSI), a measurement of the bond between cell phone and tower. Then, empirical estimates were made of the time necessary for call completion at given levels of the RSSI. The RSSI is sampled at locations throughout Erie County, New York, and this information is used to determine the probability of successful call completion for different locations within the county. This model was then applied to historic data for selected past crashes. Finally, the findings were compared with real-world crash data obtained from the ACN Field Operational Test program, where 750 ACN devices were installed in cars and their performance examined over time. An interpolated map of the sampled RSSI values suggests that cellular coverage in Erie County is adequate to support the automated collision network technology. The models and techniques described here are applicable to other areas and regions of the country.

Crash reconstruction and injury-mechanism analysis using event data recorder technology

Sophisticated onboard crash-event data recorders (EDRs) that log key vehicle dynamics information can be used to improve crash reconstruction, model occupant response, study the mechanisms of injury, and estimate occupant injury probabilities in near-real time. Such an EDR was developed and utilized as part of the Automatic Collision Notification (ACN) system for the National Highway Traffic Safety Administration. This paper presents the results of a study in which the reconstruction of an actual crash was augmented using EDR/ACN-supplied three-dimensional acceleration and other data in a vehicle occupant model configured using the Articulated Total Body (ATB) computer code. ATB-generated occupant-motion imagery and body-region acceleration response information provided valuable insights that permitted crash-reconstruction specialists to ascertain the true nature of the collision and identify the probable cause of an injury suffered by one of the victims. The authors also posit that the use of EDR data from an ACN-type system as inputs to occupant crash-response modeling may be someday support crash-victim emergency medical treatment and triage.

A prospective study of posttraumatic stress symptoms and nonadherence in survivors of a myocardial infarction (MI)

We examined a novel hypothesis that links symptoms of MI-related posttraumatic stress disorder (PTSD) to nonadherence. According to this hypothesis, patients who are traumatized by their medical illness do not take their medications as prescribed. As a part of the avoidance dimension of PTSD, patients who are traumatized may avoid being reminded of the MI by not taking the medication. MI survivors were prospectively followed for 6 months to 1 year. Adherence was assessed by pill count of Captopril. Demographic variables, medical risk factors, PTSD, and other psychiatric symptom dimensions were evaluated during follow-up. One hundred two of 140 recruited patients completed follow-up. Nonadherence to Captopril was associated with poor medical outcome (r=.93, P=.006). Above-Threshold PTSD symptoms were associated with nonadherence to medications (P=.05). No other psychiatric symptom dimensions were independently associated with nonadherence. Nonadherence to medications predicts adverse outcome during the first year after an acute MI. Nonadherence is associated with PTSD symptoms, which may either be a marker for or a cause of nonadherence. Treatment of PTSD may prove to be a useful approach for improving adherence.

High-dose intravenous isosorbide-dinitrate is safer and better than Bi-PAP ventilation combined with conventional treatment for severe pulmonary edema

OBJECTIVE

To determine the feasibility, safety and efficacy of bilevel positive airway ventilation (BiPAP) in the treatment of severe pulmonary edema compared to high dose nitrate therapy.

BACKGROUND

Although noninvasive ventilation is increasingly used in the treatment of pulmonary edema, its efficacy has not been compared prospectively with newer treatment modalities.

METHODS

We enrolled 40 consecutive patients with severe pulmonary edema (oxygen saturation <90% on room air prior to treatment). All patients received oxygen at a rate of 10 liter/min, intravenous (IV) furosemide 80 mg and IV morphine 3 mg. Thereafter patients were randomly allocated to receive 1) repeated boluses of IV isosorbide-dinitrate (ISDN) 4 mg every 4 min (n = 20), and 2) BiPAP ventilation and standard dose nitrate therapy (n = 20). Treatment was administered until oxygen saturation increased above 96% or systolic blood pressure decreased to below 110 mm Hg or by more than 30%. Patients whose conditions deteriorated despite therapy were intubated and mechanically ventilated. All treatment was delivered by mobile intensive care units prior to hospital arrival.

RESULTS

Patients treated by BiPAP had significantly more adverse events. Two BiPAP treated patients died versus zero in the high dose ISDN group. Sixteen BiPAP treated patients (80%) required intubation and mechanical ventilation compared to four (20%) in the high dose ISDN group (p = 0.0004). Myocardial infarction (MI) occurred in 11 (55%) and 2 (10%) patients, respectively (p = 0.006). The combined primary end point (death, mechanical ventilation or MI) was observed in 17 (85%) versus 5 (25%) patients, respectively (p = 0.0003). After 1 h of treatment, oxygen saturation increased to 96 +/- 4% in the high dose ISDN group as compared to 89 +/- 7% in the BiPAP group (p = 0.017). Due to the significant deterioration observed in patients enrolled in the BiPAP arm, the study was prematurely terminated by the safety committee.

CONCLUSIONS

High dose ISDN is safer and better than BiPAP ventilation combined with conventional therapy in patients with severe pulmonary edema.

Minimal heparinization in coronary angioplasty--how much heparin is really warranted?

The purpose of the study was to assess the results of percutaneous transluminal coronary angioplasty (PTCA), performed with a single intravenous bolus of 2,500 U of heparin, in a nonemergency PTCA cohort. Three hundred of 341 consecutive patients (87.9%) undergoing PTCA were prospectively enrolled in the study. They received heparin, 2,500-U intravenous bolus, before PTCA, with intention of no additional heparin administration. Patient and lesion characteristics as well as PTCA results were evaluated independently by 2 physicians. Patients were followed up by structured telephone questionnaires at 1 and 6 months after PTCA. Mean activated clotting time obtained 5 minutes after heparin administration was 185+/-19 seconds (range 157 to 238). There were 3 (1%) in-hospital major adverse cardiovascular events: 2 deaths (0.66%), 1 (0.33%) Q-wave myocardial infarction. Emergency coronary surgery and stroke were not reported. Six patients (2%) experienced abrupt coronary occlusion within 14 days after PTCA, warranting repeat target vessel revascularization. Angiographic and clinical success were achieved in 96% and 93.3%, respectively. No bleeding or vascular complications were recorded. Six-month follow-up (184 patients) revealed 3 cardiac deaths (1 arrhythmic, 2 after cardiac surgery), 1 Q-wave myocardial infarction, and 9.7% repeat target vessel revascularization. This study suggests that very low doses of heparin and reduced activated clotting time target values are safe in non-emergency PTCA, and can reduce bleeding complications, hospital stay, and costs. Larger, randomized, double-blind heparin dose optimization studies need to confirm this notion.

L-NMMA (a nitric oxide synthase inhibitor) is effective in the treatment of cardiogenic shock

BACKGROUND

The objective was to assess the safety and efficacy of L-NMMA in the treatment of cardiogenic shock.

METHODS

We enrolled 11 consecutive patients with cardiogenic shock that persisted after >24 hours from admission, despite coronary catheterization and primary percutaneous transluminal coronary revascularization, when feasible, and treatment with mechanical ventilation, intraaortic balloon pump (IABP), and high doses of catecholamines. L-NMMA was administered as an IV bolus of 1 mg/kg and continuous drip of 1 mg. kg(-1). h(-1) for 5 hours. Treatment with catecholamines, mechanical ventilation, and IABP was kept constant throughout the study.

RESULTS

Within 10 minutes of L-NMMA administration, mean arterial blood pressure (MAP) increased from 76+/-9 to 109+/-22 mm Hg (+43%). Urine output increased within 5 hours from 63+/-25 to 156+/-63 cc/h (+148%). Cardiac index decreased during the steep increase in MAP from 2. 0+/-0.5 to 1.7+/-0.4 L/(min. m(2)) (-15%); however, it gradually increased to 1.85+/-0.4 L/(min. m(2)) after 5 hours. The heart rate and the wedge pressure remained stable. Twenty-four hours after L-NMMA discontinuation, MAP (+36%) and urine output (+189%) remained increased; however, cardiac index returned to pretreatment level. No adverse events were detected. Ten out of eleven patients could be weaned off mechanical ventilation and IABP. Eight patients were discharged from the coronary intensive care unit, and seven (64%) were alive at 1-month follow-up.

CONCLUSIONS

L-NMMA administration in patients with cardiogenic shock is safe and has favorable clinical and hemodynamic effects.

Conversion of recent onset paroxysmal atrial fibrillation to normal sinus rhythm: the effect of no treatment and high-dose amiodarone. A randomized, placebo-controlled study

BACKGROUND

Spontaneous conversion of recent onset paroxysmal atrial fibrillation to normal sinus rhythm occurs commonly and is not affected by low-dose amiodarone treatment.

METHODS

In a randomized, placebo-controlled trial of 100 patients with paroxysmal atrial fibrillation of recent onset (<48 h) we compared the effects of treatment with continuous intravenous amiodarone 125 mg per hour (total 3 g) and intravenous placebo. Patients in the placebo group who did not convert to normal sinus rhythm within 24 h were started on amiodarone therapy.

RESULTS

Conversion to normal sinus rhythm occurred within 24 h in 32 of 50 patients (64%) in the placebo group, most of whom converted within 8 h. Lower conversion rates were observed in patients with hypertension, ischaemic heart disease or congestive heart failure and in patients with echocardiographic findings of left atrial diameter above 45 mm, ejection fraction below 45% or significant mitral regurgitation. However, in most patients these clinical or echocardiographic risk factors of decreases in conversion rate were not present. In such patients the spontaneous conversion rate was approximately 90%. The conversion rate during 24 h of treatment in the amiodarone group was 92% (P=0.0017, compared to the placebo group). In this group, the conversion rate was largely unaffected by baseline characteristics. Of the 18 patients who did not convert with placebo, 15 (85%) converted after being crossed over to amiodarone. All patients not responding to high-dose amiodarone were in chronic atrial fibrillation within 1 month. In patients still in atrial fibrillation after 8 h of treatment, the pulse rate decreased significantly more in the amiodarone as compared to the placebo group (83+/-15 vs 114+/-20 beats. min(-1), P=0.0014).

CONCLUSION

The spontaneous conversion of recent onset paroxysmal atrial fibrillation is high and approaches 90% in specific clinical and echocardiographically defined subgroups. Intravenous high-dose amiodarone safely facilitates conversion of paroxysmal atrial fibrillation. However, such treatment should be reserved for patients with unfavourable risk factor profiles, not converting during 8 h of observation or requiring rate control.

[Anesthesia practices in Yaounde (Cameroon)]

This descriptive and prospective study, carried out during a 6-month period at Yaounde (Cameroon), assessed work practices relating to anaesthesia in public and private health care institutions, the incidence and causes of complications, and considers possible means for improving security of the anaesthetized patient. This study included 1,103 patients, aged 12 days to 89 years. Main surgical indications were gynaecology-obstetrics (33.3% of cases) and emergency surgery (28.6% of cases). Anaesthetic practices were characterized by an unsuitable and non systematic use of procedures which are essential parts of a safe anaesthetic. Pre-anaesthetic assessment was carried out in 71.4% of cases, premedication in 78.4% of cases and management in recovery room in 24% of cases only. Patients were anaesthetized by nurses in 78.6% of cases (40% of them had been trained on-the-job only). The anaesthesia equipment of operating room was poor in most places, especially with respect to physiological monitors. The rate of complications, 476 in 321 patients (29.1% of cases), was similar to the incidence registered in 1977 (30%). Twenty-four deaths occurred (overall mortality rate of 2.2%). Besides the shortage of equipment, this study underlines the necessity for producing and adhering to guidelines for safe practice of anaesthesia, adapted for developing countries.

Usefulness of losartan, captopril, and furosemide in preventing nitrate tolerance and improving control of unstable angina pectoris

Sixty consecutive normotensive patients with unstable angina pectoris, who were on continuous intravenous isosorbide dinitrate (ISDN) treatment and had not previously received angiotensin II receptor antagonists, angiotensin-converting enzyme (ACE) inhibitors, or diuretics were randomly assigned to treatment groups receiving intravenous ISDN for 72 hours. No additional treatment was given to group A (n = 15). Captopril, in a test dose of 6.25 mg, and followed by 12.5 mg 3 times daily for 24 hours and 25 mg 3 times daily for the next 24 hours, was given to group B (n = 15). The same dose of captopril plus 40 mg of furosemide in the morning were given to group C (n = 15). Losartan, in a single dose of 25 mg/day and increased to 50 mg after 24 hours was given to group D (n = 15). Nitrate tolerance was evaluated at 24-hour intervals at trough levels of each of the drugs by administering intravenous ISDN (1 mg bolus dose every 4 minutes) and recording the total ISDN test dose required to decrease the mean arterial blood pressure by > or =10%. Treatment with continuous ISDN only (group A) induced nitrate tolerance. The ISDN (mean +/- SD) test dose was 3.5 +/- 1.8 mg at baseline, increasing to 4.9 +/- 2.4 mg at 24 hours, and 8.0 +/- 3.0 mg at 48 hours. The addition of increasing doses of captopril to the continuous ISDN treatment (group B) completely prevented nitrate tolerance. Losartan, however, did not attenuate nitrate tolerance at 24 hours and attenuated it only partially at 48 hours. The addition of furosemide to captopril had no further effect on nitrate tolerance. Of 15 patients in group A (ISDN only), 4 (27%) experienced recurrent ischemic events requiring urgent coronary catheterization. No such events were recorded in group B (captopril), but did occur in 1 patient in each of group C (captopril plus furosemide) and D (losartan) (p = 0.083). Thus, the addition of captopril to the ISDN treatment regimen prevented tolerance to nitrates and improved angina control with apparent safety. Losartan also decreased nitrate tolerance, although to a lesser extent, and also improved angina control. The addition of furosemide to captopril conferred no further benefit.

The effect of grapefruit juice on the pharmacokinetics of orally administered verapamil

OBJECTIVE

To investigate the effect of grapefruit juice (GJ) on the pharmacokinetics of orally administered verapamil in hypertensive patients.

METHODS

Ten hypertensive patients on chronic verapamil treatment participated in a two-day study. On day 1 200 ml of water was given 1 hour before, and together with the morning verapamil dose; on the day 2, water was replaced by GJ in the same order. Serial blood samples were collected and the concentrations of verapamil and its main dealkylated metabolite (D-617) were determined by high-performance liquid chromatography (HPLC). The area under the concentration versus time curve of verapamil (AUCv) and its metabolite D-617 (AUCM) were calculated before and after GJ ingestion. The peak serum concentration (Cmax) and the time until its appearance (tmax) were also determined.

RESULTS

GJ did not affect Cmax, tmax, AUCv or AUVm. The AUCv/AUCm ratio (AUCR) was slightly, but significantly, increased after GJ (1.67 vs 1.92).

CONCLUSIONS

A single administration of GJ with short-acting verapamil has no significant effect on the pharmacokinetics, of verapamil.

[Evaluation of patient recruitment at the Yaounde Central Hospital]

A rehabilitation project at Yaounde Central Hospital (YCH) under way since 1990 will soon reach completion with renovation of the maternity ward. In May 1996 three surveys designed to assess recruitment were carried out in 660 patients admitted to the Outpatient Clinic (n = 241), Emergency Room (n = 183), and other departments (n = 236). The study questionnaire focused on familial, educational, and socio-economic background, home living conditions, reasons for admission, and treatment conditions. The findings of these studies indicated that the YCH is at the top-ranked treatment facility with recruitment covering the entire city and beyond. For people living in nearby areas the YCH is also the first care provider especially since income is low. Information campaigns for users, physicians, and health care workers are needed to reinforce confidence in the YCH. The YCH must do more to promote proper management, selection, and transport of patients from upstream facilities and continue its emphasis on wide access to health facilities for the population.

Randomised trial of high-dose isosorbide dinitrate plus low-dose furosemide versus high-dose furosemide plus low-dose isosorbide dinitrate in severe pulmonary oedema

BACKGROUND

Nitrates and furosemide, commonly administered in the treatment of pulmonary oedema, have not been compared in a prospective clinical trial. We compared the efficacy and safety of these drugs in a randomised trial of patients with severe pulmonary oedema and oxygen saturation below 90%.

METHODS

Patients presenting to mobile emergency units with signs of congestive heart failure were treated with oxygen 10 L/min, intravenous furosemide 40 mg, and morphine 3 mg bolus. 110 patients were randomly assigned either to group A, who received isosorbide dinitrate (3 mg bolus administered intravenously every 5 min; n=56) or to group B, who received furosemide (80 mg bolus administered intravenously every 15 min, as well as isosorbide dinitrate 1 mg/h, increased every 10 min by 1 mg/h; n=54). Six patients were withdrawn on the basis of chest radiography results. Treatment was continued until oxygen saturation was above 96% or mean arterial blood pressure had decreased by 30% or to below 90 mm Hg. The main endpoints were death, need for mechanical ventilation, and myocardial infarction. The analyses were by intention to treat.

FINDINGS

Mechanical ventilation was required in seven (13%) of 52 group-A patients and 21 (40%) of 52 group-B patients (p=0.0041). Myocardial infarction occurred in nine (17%) and 19 (37%) patients, respectively (p=0.047). One patient in group A and three in group B died (p=0.61). One or more of these endpoints occurred in 13 (25%) and 24 (46%) patients, respectively (p=0.041).

INTERPRETATION

High-dose isosorbide dinitrate, given as repeated intravenous boluses after low-dose intravenous furosemide, is safe and effective in controlling severe pulmonary oedema. This treatment regimen is more effective than high-dose furosemide with low-dose isosorbide nitrate in terms of need for mechanical ventilation and frequency of myocardial infarction.

Effects of captopril and enalapril on zinc metabolism in hypertensive patients

OBJECTIVE

To investigate the effect of chronic captopril and enalapril treatment on zinc metabolism in hypertensive patients by assessing zinc levels in serum, urine and monocytes.

METHODS

Patients with newly diagnosed essential hypertension were randomly divided into two treatment groups: those treated with captopril only (n = 16) and those treated with enalapril only (n = 18). Ten healthy subjects served as controls. Prior to the start of treatment and again 6 months later, zinc was assessed in the serum, in urine collected over 24 hours, and in peripheral blood monocytes.

RESULTS

Significant enhancement of 24-hour urinary zinc excretion (micrograms/24 hour) after 6 months of treatment was observed only in the captopril-treated group (p < 0.01). However, intramonocytic zinc levels decreased significantly in both of the treated groups over the same period (p < 0.01 and P < 0.04 in the captopril- and enalapril-treated groups, respectively).

CONCLUSION

Treatment of hypertensive patients with captopril or enalapril may result in zinc deficiency.

[Perception of the Central Hospital by the urban population of Yaoundé: quantitative and qualitative methods]

Two studies, using different methods, were used to assess the opinions of the local population on Yaounde Central Hospital (YCH), the changes made as part of a restructuring program and use of health care facilities. The study population comprised YCH patients and the urban population of Yaounde as a whole. One study used personal interviews, according to standard epidemiological survey methods (1,267 inhabitants). The other used focus group discussions involving 8 to 12 people each (10 groups). There was no significant difference in the results recorded by these two methods. Focus group discussions are cheaper and easier to implement and are thus valuable for use alone or prior to more extensive studies using questionnaires. Classic epidemiological survey methods produce results which are reproducible and suitable for statistical analysis, and will make it possible to follow the progress of the new working policies of the YCH.

[Legal format and costs of prescriptions at the Central Hospital in Yaounde, Cameroon]

Prescribing treatment is the last act of a medical visit. A prescription is a written document that engages the medical and legal responsibility not only of the physician but of all those subsequently involved in its execution. In countries with weaker economies and more limited health care insurance the costs of filling a prescription can place a heavy financial burden on the families. In the present study we analyzed 285 prescriptions written in the Emergency Room and Outpatient Clinic of Central Hospital in Yaounde, Cameroon. In most cases prescribers were in compliance with legal requirements regarding their identity, but in 20 to 30% of cases neither the name nor function of the prescriber was mentioned. Most prescriptions were written legibly and coherently for both paramedical personnel and the patient. The number of products prescribed ranged from 2 to 5 depending on the issuing department. Practitioners in the outpatient clinic prescribed few brand-name products from the public outlet of the hospital pharmacy (16% of the prescriptions). In 68% of the cases a generic replacement was available. Practitioners in the emergency room were more apt to prescribe brand-name products (73% of the prescriptions). Five classes of drugs accounted for two thirds of prescriptions, i.e. analgesics-antipyretics, usual antibiotics, antimalarials, non-steroid anti-inflammatory drugs, and vitamins. Lawfully required information (drug presentation, route of administration, dose unit, directions and duration of treatment) was stated on 85% of prescriptions from the outpatient clinic and 50% from the emergency room. Although there were large variations, the mean cost of filling a prescription at the town pharmacy was identical in the two groups, i.e. 9500 CFA francs. The cost was 50% lower at the hospital pharmacy. All prescribers and in particular medical students should receive instruction in prescription writing. Careful selection of brand and non-brand-name drugs in agreement with practitioners should achieve further reductions in the cost of filling a prescription in hospital pharmacy.

Effects of Various Modalities of Oral Furosemide Administration in Mild or Severe Congestive Heart Failure

BACKGROUND: This study evaluated the optimal formulation (tablet vs solution) and frequency (once vs twice daily) of maintenance oral furosemide in compensated congestive heart failure (CHF). METHODS AND RESULTS: Eighteen patients with mild (group 1) and 18 with severe (group 2) CHF were studied. On 2 consecutive days each patient's individual fixed oral furosemide daily dosage was administered in tablet or solution in a crossover design. In an additional study, 14 patients with severe CHF received the daily dosage in tablet or solution form in two divided doses. Pharmacokinetic data were obtained in six randomly allocated patients of each group, during the once daily administration periods of either formulation. Twenty-four-hour urinary sodium and 12-hour volume were significantly greater in group 1 following furosemide solution versus tablets. In group 2, all parameters were comparable in response to single identical doses in tablets or solution, as well as to once versus twice daily administration of either formulation. These results coincided with a higher C(max) and a shorter t(max) following solution. CONCLUSIONS: A once-daily oral furosemide solution is more effective than the same dosage in tablet form in patients with mild, but not those with severe, CHF. In patients with severe CHF, the natriuretic and diuretic effects are similar whether oral furosemide in tablet or solution is administered in a once or twice daily schedule.

[Cost effectiveness of local regional anesthesia in a remote area]

Loco-regional anesthesia techniques are considered as a simple and economic solution to problems posed by anesthesia in developing countries. However the cost benefits of some techniques are reduced by cardiovascular effects that affect the quantity and nature of peroperative vascular filling usually necessary during general anesthesia. The purpose of the present study was to ascertain the relative costs of these methods by comparing the quantity of crystalloid solution and blood administered during loco-regional anesthesias and general anesthesias in a general hospital center in Africa. In a retrospective cohort of 1050 consecutive patients operated on in the Surgery and Gynecology/Obstetrics Departments of the A. Sice Hospital in Pointe Noire (Congo), 495 included in a study comparing perimedullary anesthesia and general anesthesia. The total volume of solution and blood administered to the patients during the procedure was studied in function of the type of anesthesia and surgery performed. Results showed that the amount of crystalloid solution administered during peridural and spinal anesthesia tended to be higher. This difference was significant only for prostate surgery. Use of epidural anesthesia did not increase the quantity of fluid modified gelatin and blood transfused in this series. It was also observed that 55% of patients who underwent peridural anesthesia required further intravenous anesthesia as opposed to 18.8% of patients who underwent spinal anesthesia. These findings indicate that loco-regional anesthesia performed under standardized conditions does not significantly change the quantity and nature of preoperative filling usually necessary during general anesthesia. Thus these techniques can be considered as cost-effective in developing countries even though the long period necessary for practitioners to learn them results in a transient increase in cost. A prospective study by surgical groups with experience using loco-regional anesthesia is needed to confirm this study.

Pancreatic enzyme elevation in measles

During an outbreak of measles in the period from May 1993 through February 1994, a 23-year-old woman with measles was admitted because of abdominal pain and vomiting. Moderately elevated levels of serum and urinary amylase were found. We investigated prospectively the next nine consecutive young adults hospitalized with severe measles. Pancreatic and other organ involvement was determined by serum and urinary amylase, serum lipase, and additional appropriate biochemical and hematological data. Four patients had elevated amylase levels in both serum and urine, whereas in one, serum amylase alone was increased. Serum lipase determined in eight patients was elevated in seven. In all patients elevated serum levels of aspartate aminotransferase and alanine aminotransferase or lactate dehydrogenase were found. In seven patients serum calcium concentrations were below the lower limit of normal. Four patients had mild to moderate thrombocytopenia. This is the first detailed report of pancreatic involvement in young adults with measles. This abnormal finding, its possible underlying mechanisms, and the clinical significance are discussed.

A new quantitative procedure for proteinuria

Abnormalities of tubular cells were treated by administration of nephrotoxin and studied by specialized gel filtration methods to discern early quantitative and qualitative changes in proteinuria. Dogs given nephrotoxic doses of Diglycoaldehyde, alpha-(hydroxymethyl)-alpha1-(6-hydroxy-9H-purine-9-yl) 60 mg per kg per day intravenously, for 3 days showed a marked reduction in effective renal plasma flow from 264.91 +/- 90.05 ml per min to 125.0 +/- 19.0 ml per min as measured by 131I sodium iodohippurate, and corresponding decrease in total renal perfusion by 131I xenon wash-out from 222.2 +/- 8.6 to 124.0 +/- 28.38. However, after treating four dogs with 20 mg per kg, an increase in effective renal plasma flow was obtained. Histologic changes of glomerular and tubular damage were demonstrated. Urine from this same series of animals was examined on a daily basis by sucrose-acrylamide gradient gel centrifugation together with ultraviolet scanning. Specific patterns were also obtained using dialyzed urine which eliminated molecules greater than 3500 mol wt. The ultraviolet pattern data were digitized and analyzed on computers to augment pattern recognition. These techniques indicted that molecules (3500 mol wt or less) were excreted in response to a known nephrotoxic agent, establishing early distinctive changes in tubular cells and also relating to alteration in renal function.