Development of a finite element model of a transtibial socket liner--an initial study

A number of computer models of limb loading by lower limb prostheses have been developed to date, however their accuracy and clinical usefulness is somewhat debatable. This paper is the first in a series describing investigations into the behaviour of a transtibial socket under compressive loading. The work focuses upon the socket liner and its role in reducing and redistributing stresses within the socket. This initial study used non-linear finite element analysis to replicate the effect of pressure loading on a polyurethane socket liner in the region of a bony prominence. It is a first step in understanding the load transfer between the residual limb, socket liner and socket of a transtibial prosthesis. The Mooney Rivlin material model [1] was used to simulate the polyurethane socket liner and compression tests in accordance with BS903 [2] were performed to gain the necessary data to calculate the Mooney Rivlin constants. Experimental validation showed that a very accurate, large-strain representation of the material was achieved. Future work will model more complex, three-dimensional geometries.

The Rapid Syndrome Validation Project (RSVP)

The Rapid Syndrome Validation Project (RSVP) is a collaboration of several institutions: Sandia and Los Alamos National Laboratories, the University of New Mexico Department of Emergency Medicine, and the NM Department of Health Office of Epidemiology. RSVP is a system that operates at the intersection of individual health care providers, public health and bioterrorism. Physicians quickly enter clinical and demographic information on patients exhibiting symptoms and signs of the syndromes of interest. It provides early warning and response to emerging biological threats, as well as emerging epidemics and diseases. RSVP provides real time clinical information to the provider and any other potential user such as the DOH, about current symptoms, disease prevalence and location. The system also serves as a mechanism for the Department of Health to inform health care providers of health alerts and to facilitate the process of collecting data on reportable diseases. We describe here the purpose an the architecture of a network-based surveillance system that is currently implemented in an Emergency Department.

Modeling the interactions between a prosthetic socket, polyurethane liners and the residual limb in transtibial amputees using non-linear finite element analysis

Continuing earlier studies into the relationship between the residual limb, liner and socket in transtibial amputees, we describe a geometrically accurate non-linear model simulating the donning of a liner and then a socket. The socket is rigid and rectified and the liner is a polyurethane geltype which is accurately described using non-linear (Mooney-Rivlin) material properties. The soft tissue of the residual limb is modelled as homogeneous, non-linear and hyperelastic and the bone structure within the residual limb is taken as rigid. The work gives an indication of how the stress induced by the process of donning the rigid socket is redistributed by the liner. Ultimately we hope to understand how the liner design might be modified to reduce discomfort. The ANSYS finite element code, version 5.6 is used.

Effects of streptokinase and deoxyribonuclease on viscosity of human surgical and empyema pus

STUDY OBJECTIVE

To investigate the effects of streptokinase and deoxyribonuclease (DNase) on the viscosity of pus to assess whether the DNase in the old preparation of streptokinase-streptodornase used intrapleurally to treat empyema was contributing to easier drainage of pus compared with purified streptokinase.

DESIGN

In vitro measurement of pus viscosity.

PATIENTS

Pus from three patients with surgically drained soft tissue abscesses and from six patients with empyema thoracis of varying etiology was studied.

INTERVENTIONS

Pus samples were incubated with saline solution as control and with streptokinase, streptokinase-streptodornase, human recombinant DNase, and a mixture of streptokinase and DNase in concentrations approximating those achieved in clinical practice.

RESULTS

Purified streptokinase had little effect on pus viscosity, with a mean reduction of 11.1% in the surgical specimens and 1.7% in the empyema samples. Streptokinase-streptodornase reduced viscosity by a mean of 52.8% in the surgical samples and 94.8% in the empyema samples. Human recombinant DNase reduced viscosity by a mean of 32. 79% in surgical samples and 93.4% in empyema samples. Adding streptokinase to human recombinant DNase produced no further reduction in viscosity. Final viscosities in samples treated with DNase were very similar whatever the starting viscosity.

CONCLUSIONS

DNase significantly reduces pus viscosity, whereas streptokinase has little or no effect, and in empyema may work simply by breaking down loculations. Clinical studies should be undertaken to see if these in vitro changes produce clinical benefits. The simple viscometer devised for these experiments may also prove useful in other contexts.

Cultural variations in the understanding of traumatic brain injury and brain injury rehabilitation

Little is known about how people from different cultures experience and understand traumatic brain injury (TBI) and the process of brain injury rehabilitation. The Brain Injury Rehabilitation Unit (BIRU) undertook a qualitative project to research cultural variations in the understanding of TBI and the rehabilitation process, interviewing 39 people with TBI and family members from Italian, Lebanese and Vietnamese backgrounds. The focus was on the reporting of sequelae of the TBI; valued qualities of service providers; barriers to effective communication; the role of the families in the rehabilitation process; and the experience of social stigma. Findings suggest there is a universal experience of TBI that transcends individual cultures. Study participants valued attentiveness, friendliness and guidance from rehabilitation staff. Family support was not always available to the person with TBI due to family conflict. Generally, people with TBI and family members valued the assistance of health interpreters facilitating their communication with rehabilitation staff. People with TBI from all three cultures experienced problems of stigma and social isolation. The findings have a number of implications for how brain injury rehabilitation staff can approach service provision to people from diverse cultural backgrounds.

Scuba diving medical examinations in practice: a postal survey

OBJECTIVE

To assess variability of opinion regarding fitness to dive among doctors currently doing diving medical examinations.

DESIGN

Anonymous, reply-paid postal survey containing 15 clinical scenarios for which respondents were asked to declare the prospective scuba diver fit, unfit, fit after investigation or to offer specialist referral.

PARTICIPANTS

All 81 doctors in Queensland, identified as members of the South Pacific Underwater Medical Society, who had completed approved training in underwater medicine, and who were doing diving medical examinations in June 1998.

MAIN OUTCOME MEASURES

Variability in responses, and agreement with our interpretation of the action recommended by Australian Standard (AS) 4005.1-1992, the medical standard for fitness to scuba dive for recreational divers.

RESULTS

52 of the 81 questionnaires were returned (64% response rate). There was a wide variety of opinion about fitness to dive for all 15 hypothetical cases, with 70% consensus about unfitness in only four cases (one of which should have been referred according to AS guidelines) and fitness in only two cases (both of which should have been referred according to AS guidelines). No case was considered either fit or unfit by all respondents. Only 17.6% of responses recommended specialist referral, although the AS guidelines suggest that 10 of the 15 cases should be referred. One doctor failed 13 of the 15 potential divers outright and another passed seven outright and failed only four. For each case that the AS guidelines firmly indicate as unfit to dive, at least one respondent passed the hypothetical prospective diver as fit.

CONCLUSIONS

There is no consensus among doctors who perform diving medical examinations as to what constitutes fitness to dive; current guidelines need to be improved.

Tuberculosis in Far North Queensland, Australia

SETTING

Regional thoracic clinic in tropical Australia.

OBJECTIVE

To document recent experience with tuberculosis in Far North Queensland, Australia, with particular reference to tuberculosis in indigenous people.

METHODS

Retrospective survey of all cases of tuberculosis in Far North Queensland between January 1993 and December 1997.

RESULTS

There were 87 cases of tuberculosis; 54 were pulmonary, of which 67% were sputum smear-positive. Crude annual incidence of tuberculosis in indigenous people was 35.9/100,000 population compared to 2.32/ 100,000 in non indigenous people. There were 15 deaths, seven of which were felt to be avoidable. Nine of 11 relapses of previously treated disease occurred in Aboriginals. There were six cases of initial drug resistance, of which four were imported from overseas. Contact tracing identified four active cases of tuberculosis and 102 recently infected contacts. Preventive treatment in infected contacts was completed in only 41%, largely because of poor compliance related to alcohol consumption.

CONCLUSION

Tuberculosis remains common in Far North Queensland, with excess cases observed mainly in the indigenous population. Aboriginals are at high risk of both death from and relapse of tuberculosis. Tuberculosis control in indigenous people scattered over such a vast area remains challenging, and the results at present are sub-optimal.

Sex offending as a psychosocial sequela of traumatic brain injury

OBJECTIVE

To describe the nature and extent of sexual offending after traumatic brain injury (TBI).

DESIGN

Retrospective file review.

SETTING

A brain injury unit providing inpatient and outpatient rehabilitation services.

PARTICIPANTS

A review of five years of admissions to the Brain Injury Rehabilitation Unit (N = 477) identified a sample of 29 males who committed 128 incidents of sex offending.

MAIN OUTCOME MEASURES

A protocol to record data on demographic, injury, radiological, and psychosocial variables and offending behaviors.

RESULTS

Of the total population of 445 clients with TBI, 6.5% (n = 29) were identified as having committed some form of sexual offense. Alcohol was a factor in only three (2.3%) of the incidents, and only two clients had a preinjury history of sexual offending. The most common offenses were the "touching" offenses, followed by exhibitionism and overt sexual aggression. Staff members were the most common targets of the offenses, followed by members of the general public, other people with TBI, and family members.

CONCLUSIONS

Sex offending is a significant clinical problem among a small minority of men after TBI. The absence of alcohol and preinjury histories of sexual offending suggest that the brain injury and contingent sequelae were a significant etiological factor underlying the offenses. A number of implications for the clinical management of clients with sexually aberrant behaviors is identified and discussed.

A systematic approach to evaluate the modification of lens proteins by glycation-induced crosslinking

To systematically evaluate the modification of lens proteins by aldose and dicarbonyl sugars during the glycation process, the sugar-dependent incorporation of Lys and Arg, SDS-PAGE profile, amino acid analysis, and fluorophore formation (excitation 370 nm/emission 440 nm) were determined. Reaction mixtures with glycolaldehyde, glyceraldehyde, threose and 3-deoxythreosone showed the greatest extent of Lys crosslinking and fluorescence formation. An increase in fluorescence intensity, but a decrease in Lys and Arg crosslinking, was found with glyoxal, methylglyoxal, hydroxypyruvaldehyde and threosone. In addition glyoxal, methylglyoxal and hydroxypyruvaldehyde caused the specific loss of Arg residues in lens proteins. Reaction mixtures with xylose, xylosone, glucose, glucosone and 3-deoxyglucosone exhibited the least protein modifications; however, incubation with 3-deoxyxylosone resulted in extensive loss of Lys and Arg residues, a higher extent of Lys or Arg crosslinking and significant fluorophore formation. Each sugar exhibited unique characteristics in the modification of lens proteins by glycation. To validly compare the protein modifications occurring during glycation reactions, a systematic approach was employed to evaluate the potential role of aldose and dicarbonyl sugars in protein modification.

A phase II/III trial of antimicrobial therapy with or without amikacin in the treatment of disseminated Mycobacterium avium infection in HIV-infected individuals. AIDS Clinical Trials Group Protocol 135 Study Team

OBJECTIVE

To determine the clinical and microbiologic benefit of adding amikacin to a four-drug oral regimen for treatment of disseminated Mycobacterium avium infection in HIV-infected patients.

DESIGN

A randomized, open-labeled, comparative trial.

SETTING

Outpatient clinics.

PATIENTS

Seventy-four patients with HIV and symptomatic bacteremic M. avium infection.

INTERVENTIONS

Rifampin 10 mg/kg daily, ciprofloxacin 500 mg twice daily, clofazimine 100 mg every day, and ethambutol 15 mg/kg orally daily for 24 weeks, with or without amikacin 10 mg/kg intravenously or intramuscularly 5 days weekly for the first 4 weeks.

MAIN OUTCOME MEASURE

Clinical and microbiologic response at 4 weeks; quantitative level of bacteremia with M. avium.

RESULTS

No difference in clinical response was noted with the addition of amikacin to the four-drug oral regimen, and only 25% in either group had a complete or partial response at 4 weeks. A comparable quantitative decrease in bacteremia was noted in both treatment groups, with 16% of patients being culture-negative at 4 weeks and 38% at 12 weeks. Toxicities were mainly gastrointestinal. Amikacin was well tolerated. Median survival was 30 weeks in both groups.

CONCLUSIONS

The addition of amikacin to a four-drug oral regimen of rifampin, ciprofloxacin, clofazimine, and ethambutol did not provide clinical or microbiologic benefit.

Differential sensitivities to risperidone and olanzapine in a human immunodeficiency virus patient

BACKGROUND

Neuroleptic sensitivity presents a considerable problem for the treatment of psychosis in the acquired immunodeficiency syndrome (AIDS) and human immunodeficiency virus (HIV)-positive patient population. As yet, there are few data on the response of these patients to newer atypical antipsychotic medications.

METHODS

We present the detailed medication history of a 33-year-old man with AIDS, who had a prior history of extrapyramidal symptoms (EPS) with both typical antipsychotics and risperidone, and was treated with olanzapine for major depression with psychotic features.

RESULTS

The patient developed akathisia in a dose-dependent manner at dosages between 10 and 15 mg daily of olanzapine, but no EPS. Akathisia responded to dose reduction and use of beta-adrenergic blockade.

CONCLUSIONS

The AIDS patient may exhibit sensitivity even to newer atypical antipsychotics. The lack of EPS and response to a beta-blocker underscore the different mechanisms causing akathisia and EPS.

The generation of superoxide anions in glycation reactions with sugars, osones, and 3-deoxyosones

Glycoxidation is a process whereby glycated proteins chemically generate oxygen free radicals. Superoxide anion formation was measured by the superoxide dismutase-dependent reduction of ferricytochrome C in glycation reactions at pH 7.0 in the absence of transition metal ions. Assays were linear over 1 h, and most activity was seen after a 2 d incubation of 5 mM L-threose and 10 mM alpha-N-acetyl-lysine (N-Ac-Lys) or 10 mg/mL RNase A. Trioses, tetroses and their corresponding osones and 3-deoxyosones had the highest activity (12-16 nmoles O.-2/hr/ml) with N-Ac-Lys. Osones and 3-deoxyosones alone generated considerable O.-2, whereas aldose sugars largely did not. Xylosone and 3-deoxyxylosone produced 6 and 10 nmoles O.-2/hr/ml respectively with N-Ac-Lys, however, xylose was inactive, as were glucose and fructose. Glycation assays with 3-deoxyglucosone and glyoxal showed no activity, however, methyl glyoxal generated 1.7 and 2.0 nmoles O.-2/hr/ml with N-Ac-Lys and N-Ac-Arg, respectively. Therefore, Amadori compounds composed of lysine and short chain sugars can rapidly generate superoxide anion in the absence of metal ions.

Access to health care. Part 2: Working-age adults

OBJECTIVES

This report presents data on access to health care for U.S. working-age adults, 18-64 years old. Access indicators are examined by selected sociodemographic characteristics including sex, age, race and/or ethnicity, place of residence, employment status, income, health status, and health insurance status.

METHODS

Data are from the 1993 Access to Care and 1993 Health Insurance Surveys of the National Health Interview Survey (NHIS), a continuing household survey of the civilian noninstitutionalized population of the United States. The sample contained 61,287 persons in 24,071 households.

RESULTS

In 1993, approximately 3 out of 4 working-age adults had a regular source of medical care. Nine out of 10 adults with health insurance had a regular source of care compared with 6 out of 10 adults without health insurance. For adults with a regular source of care, 86 percent received care in a private doctor's office, 9 percent in a clinic, and 2 percent in a hospital emergency room. The two main reasons given for not having a regular source of care were "do not need a doctor" (49 percent), and "no insurance can't afford it" (22 percent). Persons in the highest income group were more likely to report no need for a doctor (59 percent) than persons in the lowest income group (35 percent). About 40 percent of uninsured persons and 16 percent of insured persons reported an unmet medical need.

CONCLUSIONS

Health insurance plays a key role in the access to medical care services. Persons who are uninsured or have low incomes are at the greatest risk of having unmet medical needs.

Access to health care. Part 1: Children

OBJECTIVES

This report presents national estimates of access to medical care and unmet health care needs for children through 17 years of age by selected sociodemographic variables including sex, age, race and/or ethnicity, family income, family structure, place of residence, and health status. In addition, the impact of children's health insurance status on access to care is described.

METHODS

Data from the 1993 Access to Care and Health Insurance questionnaires of the National Health Interview Survey (NHIS) are analyzed to examine access indicators. The NHIS is a continuing household survey of the civilian noninstitutionalized population of the United States. The sample included 16,907 children from infants through 17 years of age from 24,071 households.

RESULTS

In 1993, over 7.3 million U.S. children had at least one unmet health care need or had medical care delayed because of worry about the cost of care. These health care needs included medical care, dental care, prescription medicine, glasses, and mental health care. In addition, almost 4.2 million children lacked a regular source of health care. Factors related to access indicators included health insurance, family income, race and/or ethnicity, family structure, and place of residence. The lack of health insurance or inability to afford care was the main reason given by respondents for children lacking a regular source of medical care.

CONCLUSIONS

In the United States, millions of children do not receive needed health care services. Uninsured children and those in families with low income are at the greatest risk of having unmet health needs.

Access to health care. Part 3: Older adults

OBJECTIVES

This report examines access to health care for older adults, 65 years of age and over. In the United States for 1993. Access indicators include having a regular source of care, place of care, main reason for no regular source of care, unmet health care needs, and use of clinical and preventive services. Sociodemographic characteristics include sex, age, race, income, health status, and health insurance coverage.

METHODS

Data are from the 1993 Access to Care, Health insurance, and Year 2000 Surveys of the National Health interview Survey (NHIS), a continuing household survey of the civilian noninstitutionalized population of the United States. The sample for the Access to Care and Health insurance surveys contained 61,287 persons in 24,071 households. The sample for the Year 2000 survey was 21,028 persons.

RESULTS

Persons with Medicare and private or Medicare and public coverage were more likely to have a regular source of medical care than elderly persons with Medicare only. Over 3.3 million elderly persons had at least one unmet need in 1993. Older adults on Medicare and public or Medicare only coverage were twice as likely to have unmet medical needs than those with Medicare and private coverage. Persons with Medicare and private coverage were more likely to receive immunizations than elderly persons with Medicare and public coverage or Medicare only.

CONCLUSIONS

Although the majority of older adults have Medicare, this only provides a basic level of access to the health care system. Older adults who do not supplement Medicare with private coverage are at the greatest risk of having unmet health care needs.

Nurses' attitudes toward computerization in clinical practice in a British general hospital

The growth of information technology systems associated with the organizational reforms of the British Health Service has given rise to a need to understand nurses' attitudes toward computerization. Several studies in the United States have identified various factors that influence nurses' computer-related attitudes but such studies in the United Kingdom are rare. This study sampled 208 nurses in a general hospital of approximately 500 beds, and measured their computer-related attitudes using Stronge and Brodt's questionnaire. Demographic data specifically related to the UK scene also were collected. Although nurses' computer-related attitudes generally were positive, significant differences were found in relation to age, length of service as a trained nurse, job title, type of nursing unit, and length of service at the study hospital. Brodt and Stronge also found significant differences related to length of time as a trained nurse and nursing unit, but not for length of service or age. Discussion of the study findings suggests that the UK scene is not dissimilar to that in the United States. However, comparison of findings with Brodt and Stronge's work raises some questions about trends in nurses' computer-related attitudes and about the usefulness of computer technology to professional nursing practices.

Effects of serum separation tubes on serum benzodiazepine and phenobarbital concentrations in clinically normal and epileptic dogs

OBJECTIVE

To characterize the effects of serum separation tubes (SST) on serum drug concentrations.

SAMPLE POPULATION

Clinically normal dogs (clorazepate, n = 7) or dogs with epilepsy (phenobarbital, n = 7) were studied in experiment 1, and samples submitted for therapeutic drug monitoring (n = 87) were studied in experiment 2.

PROCEDURE

In experiment 1, blood containing either drug was placed in 2 types of 4-ml SST (SST-A and SST-B) and in nonserum separation tubes (non-SST [control]). Samples were processed, then stored at 20 to 22 C (both drugs) or 10 C (phenobarbital only). Aliquots were collected for 96 hours. The rate constant of disappearance and the percentage decrease of each drug over time were determined for each tube. For experiment 2, paired samples were collected in non-SST and SST and submitted by mail for therapeutic drug monitoring. The SST samples were either decanted from SST prior to shipment (group 1; n = 30) or mailed in SST with serum in contact with the silica gel (group 2; n = 57). Drug concentrations and drug elimination half-life were compared between groups. For both experiments, drugs were detected in samples, using polarized immunofluorescence.

RESULTS

For experiment 1, the rate constant of drug disappearance for both drugs was greater in the 4-ml SST-A (P < 0.0001). This SST also caused the greatest percentage decrease (20% for phenobarbital and 35% for benzodiazepines) at 96 hours. Refrigeration reduced the mean decrease in phenobarbital at 96 hours to 11%. For experiment 2, phenobarbital concentration was lower for both SST, compared with non-SST (P < 0.0005). Phenobabital had decreased a mean 6.4 +/- 0.5% in group-1 and a mean 30.5 +/- 11.1% in group-2 (P < 0.0005) samples.

CONCLUSION

The SST should be avoided when collecting serum for monitoring of either phenobarbital or benzodiazepines.

CLINICAL RELEVANCE

The SST can falsely decrease serum drug concentrations and should be avoided when collecting blood for therapeutic drug monitoring.

Oral ganciclovir for the prevention of cytomegalovirus disease in persons with AIDS. Roche Cooperative Oral Ganciclovir Study Group

BACKGROUND

In the advanced stages of the acquired immunodeficiency syndrome (AIDS), cytomegalovirus (CMV) disease, particularly vision-damaging retinitis due to CMV is common. We evaluated prophylactic treatment with orally administered ganciclovir as a way to prevent CMV disease.

METHODS

We conducted a prospective, randomized, double-blind, placebo-controlled study of CMV infected persons with AIDS with either CD4+ lymphocyte counts of < or = 50 per cubic millimeter or counts of < or = 100 per cubic millimeter in those with a history of an AIDS defining opportunistic infection. Patients were randomly assigned, in a 2:1 ratio, to receive either oral ganciclovir (1000 mg three times daily) or placebo.

RESULTS

The study was stopped after a median 367 days of follow-up. In an intention-to-treat analysis, the twelve month cumulative rates of confirmed CMV disease were 26 percent in the placebo group (n = 239) and 14 percent in the ganciclovir group (n = 486), representing an overall reduction in risk of 49 percent in the ganciclovir group (P < 0.001). The incidence of CMV retinitis after 12 months was 24 percent in the placebo group and 12 percent in the ganciclovir group (P < 0.0001). The prevalence of CMV-positive urine cultures at base line was 42 percent; after two months it was 43 percent in the placebo group and 10 percent in the ganciclovir group (P < 0.0001). The one year mortality rate was 26 percent in the placebo group and 21 percent in the ganciclovir group (P = 0.14). Therapy with granulocyte colony stimulating factor was more frequent in the ganciclovir group (24 percent) than in the placebo group (9 percent).

CONCLUSIONS

In persons with advanced AIDS, phophylactic oral ganciclovir significantly reduces the risk of CMV disease.

Preventing childhood unintentional injuries--what works? A literature review

AIM

The aim of this paper is to report on a systematic review of the world literature to provide information about the most effective forms of health promotion interventions to reduce childhood (0-14 years) unintentional injuries. The findings are of relevance to policy makers at a local or national level, to practitioners and researchers.

METHODS

The relevant literature has been identified through the use of electronic databases, hand searching of journals, scanning reference lists, and consultation with key informants.

RESULTS

Examples of interventions that have been effective in reducing injury include: bicycle helmet legislation, area wide traffic calming measures, child safety restraint legislation, child resistant containers to prevent poisoning, and window bars to prevent falls. Interventions effective in changing behaviour include bicycle helmet education and legislation, child restraint legislation, child restraint loan schemes, child restraint educational campaigns, pedestrian education aimed at the child/parent, provision of smoke detectors, and parent education on home hazard reduction. For the community based campaigns, the key to success has been the sustained use of surveillance systems, the commitment of interagency cooperation and the time needed to develop networks and implement a range of interventions. Education, environmental modification and legislation all have a part to play and their effect in combination is important.

CONCLUSION

The design of evaluations in injury prevention needs to be improved so that more reliable evidence can be obtained. Better information is needed on process, so that successful strategies can be replicated elsewhere. There is also a need for literature reviews on effectiveness to be updated regularly and for their findings to be widely disseminated to policy makers, researchers, and practitioners.

Comparison of three regimens for treatment of mild to moderate Pneumocystis carinii pneumonia in patients with AIDS. A double-blind, randomized, trial of oral trimethoprim-sulfamethoxazole, dapsone-trimethoprim, and clindamycin-primaquine. ACTG 108 Study Group

OBJECTIVE

To compare the tolerability and efficacy of three oral regimens for the treatment of patients with the acquired immunodeficiency syndrome (AIDS) and Pneumocystis carinii pneumonia.

DESIGN

A randomized, double-blind study.

SETTING

24 U.S. academic medical centers.

PATIENTS

181 patients with morphologically confirmed P. carinii pneumonia and alveolar-arterial oxygen differences (PAO2-PaO2) of 45 mm Hg or less.

INTERVENTION

Patients were randomly assigned to receive trimethoprim-sulfamethoxazole, dapsone-trimethoprim, or clindamycin-primaquine for 21 days. Patients with a PAO2-PaO2 of 35 to 45 mm Hg at study entry also received prednisone.

MEASUREMENTS

Serial clinical and laboratory evaluations for therapeutic response and toxicity. Therapeutic failure at day 21 was defined by any of the following: increase in PAO2-PaO2 of greater than 20 mm Hg; no remission of baseline signs and symptoms; and change in antipneumocystis therapy for reasons other than toxicity, intubation, or death. Dose-limiting toxicity was defined as discontinuation of therapy by the primary physician because of one or more adverse reactions.

RESULTS

No statistically significant differences were seen among treatment groups in the proportions of patients who had dose-limiting toxicity (P=0.2), therapeutic failure (P>0.2), or a complete course of therapy (P>0.2). Survival during therapy or for 2 months thereafter did not differ among the three groups (P>.02). However, elevation of serum aminotransferase levels to more than five times the baseline levels was more frequent in the trimethoprim-sulfamethoxazole group (P=0.003), and one or more serious hematologic toxicities (neutropenia, anemia, thrombocytopenia, or methemoglobinemia) occurred more frequently in the clindamycin-primaquine group (P=0.01).

CONCLUSIONS

The rates of dose-limiting toxicity, therapeutic failure, and survival did not differ among patients with AIDS who were receiving oral trimethoprim-sulfamethoxazole, dapsone-trimethoprim, or clindamycin-primaquine for mild to moderate P. carinii pneumonia. However, the limited sample size prevents the unequivocal demonstration of the equality of these three regimens. Differences in expected categories of toxicities associated with each regimen should guide the clinician in choosing first-line therapy, particularly for patients with baseline hepatic insufficiency or myelosuppression.

Statistical analysis of blood- to breath-alcohol ratio data in the logarithm-transformed and non-transformed modes

The statistical analysis of non-transformed and logarithm-transformed blood- to breath-alcohol ratios ("blood/breath ratios") is detailed. The data analyzed were derived from 137 simultaneous blood-alcohol and breath-alcohol concentration measurements made between 15 and 179 min after the end of drinking, with 136 of the measurements obtained during the 15- to 124-min time frame. Although the distribution of the non-transformed ratios is positively skewed, and that of the logarithm-transformed data more closely approximates the normal distribution upon visual inspection, both analyses generated results that do not differ significantly from each other when considered in the context of "mean ratios + or - 2SD". This is in accord with the results of the Kolmogorov-Smirnov goodness-of-fit test, which does not reject either dataset and demonstrates that both are approximately normal. Since the logarithm-transformed data generate more conservative statistical blood/breath ratio ranges than the non-transformed data, they were selected as the basis for the principal conclusion of this work. That conclusion is a refutation of the argument that, breath-alcohol analyzers relying on a 2100:1 blood/breath ratio tend to underestimate the blood-alcohol concentrations of driving-while-intoxicated arrestees because the commonly accepted mean postabsorptive ratio is 2300:1. In fact, whenever the absorption status of a driving-while-intoxicated arrestee at the time of a breath test cannot be definitively established, the results of this work support the application of a relative error range of -40% to +28% for 95% of the population, based on a statistical blood/breath ratio range of 1259:1 to 2679:1, and -46% to +42% for 99% of the population, based on a statistical range of 1128:1 to 2989:1.