Critical review of the epidemiology literature on the potential cancer risks of methylene chloride

OBJECTIVE

To critically review and summarize the epidemiological evidence published to date on the carcinogenicity of methylene chloride to humans.

METHODS

Papers for review were identified through Medline (National Library of Medicine) and were limited to epidemiology studies. Studies were classified using three categories. Primary studies focused on the association between methylene chloride and cancer among occupational cohorts primarily exposed to methylene chloride. Secondary studies identified methylene chloride a priori as a potential exposure of interest, and the investigators either characterized the methylene chloride exposure or described results for the methylene chloride-exposed workers separately. Tertiary studies evaluated cohorts either minimally exposed to methylene chloride or presumed exposed but for which no exposure estimation or separate classification was made.

RESULTS

No strong or consistent finding for any site of cancer was apparent despite several studies of large occupational cohorts of workers potentially exposed to high concentrations of methylene chloride. Sporadic and weak associations were reported for cancers of the pancreas, liver and biliary passages, breast, and brain. Although these studies collectively cannot rule out the possibility of any cancer risk associated with methylene chloride exposure, they do support a conclusion of no substantive cancer risk.

CONCLUSIONS

Continued follow-up of the established cohorts may elucidate the few and inconsistent relationships reported to date; however, it appears likely that risks associated with methylene chloride exposure, if any, are small and limited to rare cancers. The usefulness of additional cohort studies for the evaluation of cancer risks associated with methylene chloride exposure will depend largely on whether the relevant exposure period has passed and whether exposure characterization (e.g., peak or intermittent exposure or intensity) can be improved.

Blood glucose and neurologic outcome with global brain ischemia

OBJECTIVE

To investigate the relationship between neurologic outcome and blood glucose concentrations in survivors of cardiopulmonary arrest.

DESIGN

Retrospective case series chart review.

SETTING

Adult multidisciplinary intensive care unit (ICU) of a tertiary referral medical center.

SUBJECTS

Consecutive patients over a 12-month period surviving cardiopulmonary resuscitation (CPR).

INTERVENTIONS

Variables that were examined that could affect the relationship between the circulating glucose concentration and neurologic outcome included: location of arrest (inhospital/out-of-hospital), age, history of diabetes mellitus, duration of arrest, CPR duration, initial cardiac rhythm, and drugs administered during arrest. Cerebral recovery was evaluated by a 5-point outcome scale (Glasgow Pittsburgh Brain Stem Score) on ICU admission, and 24 and 48 hrs after ICU admission.

MEASUREMENTS AND MAIN RESULTS

Observations were made on 85 patients, of whom 67% had inpatient CPR and 33% received out-of-hospital CPR. The duration of arrest of 66 (78%) patients was <5 mins. Mean CPR duration was 13.7 mins. Twenty-one percent of patients had diabetes. The mean blood glucose concentration post-CPR (n = 80) was 272 mg/dL (15.1 mmol/L). A statistically significant association was shown between high glucose concentration post-CPR and severe cerebral outcome among a small subset of patients with CPR lasting >5 min.

CONCLUSIONS

The present study does not support an association between the concentration of glucose post-CPR and neurologic outcome. The previously reported casual relationship between hyperglycemia and neurologic prognosis may be an epiphenomenon of the severity of global cerebral ischemia in humans.

Recombinant human erythropoietin utilization in Department of Veterans Affairs dialysis units

This study was carried out to determine the use of recombinant human erythropoietin (rHuEPO) in the Veterans Affairs dialysis program and any strategies being carried out to enhance its effectiveness. The data were collected from a survey that was conducted using a questionnaire sent to all Veterans Affairs dialysis programs. The survey included all patients treated with hemodialysis or peritoneal dialysis for at least 3 months and who were receiving rHuEPO for at least 3 months. Patients diagnosis, age, length of time of dialysis, mode of dialysis, length of rHuEPO treatment, route of administration, assessment of iron stores, use of iron supplementation, and use of androgens were assessed by this questionnaire and analyzed for their effect on dose required to achieve a target hematocrit. Subcutaneous administration resulted in a significantly lower dose requirement compared with the dose required when rHuEPO was administered intravenously. Concomitant use of androgens resulted in a lower dose requirement for rHuEPO when it was given intravenously, but not when rHuEPO was given subcutaneously. The dose required to maintain the hematocrit at the designated level appeared to increase with time of treatment.

Self-reports of HIV risk factors by patients at a sexually transmitted disease clinic: audio vs written questionnaires

OBJECTIVES

The purpose of this study was to determine how the method of assessment affects patient report of human immunodeficiency virus (HIV) risks.

METHODS

Patients at a sexually transmitted disease clinic randomly received either a written self-administered questionnaire or an audio self-administered questionnaire delivered by cassette player and headset. These questionnaires were followed by face-to-face interviews.

RESULTS

Audio questionnaires had fewer missing responses than written questionnaires. Audio questionnaires also identified more unprotected vaginal intercourse and sexual partners suspected or known to have HIV infection or acquired immunodeficiency syndrome than did written questionnaires. Although both the audio and written questionnaires identified more risks than the face-to-face interviews, the difference in the mean number of reported risks between the audio questionnaires and the face-to-face interviews was greater than that between the written questionnaires and the face-to-face interviews.

CONCLUSIONS

Audio questionnaires may obtain more complete data and identify more HIV risk than written questionnaires. Research is warranted about whether audio questionnaires overcome barriers to the completion and accuracy of HIV risk surveys. This study emphasizes the need to elucidate the relative strengths and weaknesses of written questionnaires, audio questionnaires, and face-to-face interviews for HIV risk assessment.

Effect of epidural morphine on sedation requirements during regional anesthesia

STUDY OBJECTIVE

To examine the effect of using analgesic doses of epidural morphine on midazolam requirements for conscious sedation during regional anesthesia.

DESIGN

Randomized, double-blind, placebo-controlled trial.

SETTING

Operating rooms at a university hospital.

PATIENTS

20 ASA physical status II and III patients aged 50 to 70 years undergoing elective peripheral vascular reconstruction with epidural anesthesia.

INTERVENTIONS

At the beginning of surgery, 10 patients received 3 mg of epidural morphine, and the other 10 patients received normal saline epidurally. All patients received midazolam intravenously in bolus doses and as a continuous infusion to maintain a steady state of sedation throughout surgery.

MEASUREMENTS AND MAIN RESULTS

There was no difference between the dose of midazolam required to maintain sedation in the two groups during the first 3 hours of the study. Beyond the third hour, the midazolam dose required to maintain the same level of sedation was significantly higher in the placebo group than in the epidural morphine group (p = 0.05).

CONCLUSION

An analgesic dose of epidural morphine, after a latent period of 3 hours, may decrease the dose of midazolam required for sedation using regional anesthesia.

The resting volume and compliance characteristics of the bronchial cuff of left polyvinyl chloride double-lumen endobronchial tubes

The resting volume of a low-pressure, high-volume cuff is an important factor that determines the cuff compliance, because it is the maximum volume that maintains the low-pressure characteristics of the cuff. Modern polyvinyl chloride (PVC) double-lumen tubes (DLT) are designed with a low-pressure bronchial cuff to minimize the risk of bronchial damage. Maintenance of the low-pressure characteristics of this cuff, however, requires knowledge of how its resting volume and compliance vary between different DLT sizes and brands, and how the compliance changes when the cuff is inflated inside different-sized bronchi. We, therefore, measured the bronchial cuff pressure-volume relationship for each of the adult sizes, 35 Fr, 37 Fr, 39 Fr, and 41 Fr, of the Mallinckrodt, Sheridan, Rusch, and Portex left DLTs. The compliance of each cuff was characterized by: 1) the cuff resting volume, defined as the smallest cuff volume beyond which a 0.5-mL increase in volume resulted in more than 10 mm Hg increase in cuff pressure; and 2) the cuff pressure at 3-mL volume. Measurements were repeated for sizes 35 Fr and 41 Fr left Mallinckrodt DLTs with the bronchial cuff lying inside two canine left main-stem bronchi measuring 11 mm and 13 mm in diameter. The bronchial cuff resting volume ranged from 1.5 to 5.0 mL in different sizes and brands of DLTs, which could be explained by differences in cuff size between different manufacturers and between different DLT sizes of the same manufacturer.(ABSTRACT TRUNCATED AT 250 WORDS)

An epidemiologic study of sports and weight lifting as possible risk factors for herniated lumbar and cervical discs. The Northeast Collaborative Group on Low Back Pain

The associations between participation in several specific sports, use of free weights, and use of weight lifting equipment and herniated lumbar or cervical intervertebral discs were examined in a case-control epidemiologic study. Specific sports considered were baseball or softball, golf, bowling, swimming, diving, jogging, aerobics, and racquet sports. Included in the final analysis were 287 patients with lumbar disc herniation and 63 patients with cervical disc herniation, each matched by sex, source of care, and decade of age to 1 control who was free of disc herniation and other conditions of the back or neck. Results indicated that most sports are not associated with an increased risk of herniation, and may be protective. Relative risk estimates for the association between individual sports and lumbar or cervical herniation were generally less than or close to 1.0. There was, however, a weak positive association between bowling and herniation at both the lumbar and cervical regions of the spine. Use of weight lifting equipment was not associated with herniated lumbar or cervical disc, but a possible association was indicated between use of free weights and risk of cervical herniation (relative risk, 1.87; 95% confidence interval, 0.74 to 4.74).

A comparison of combined amrinone and glucagon therapy to glucagon alone for cardiovascular depression associated with propranolol toxicity in a canine model

Multiple inotropic agents may be required to improve hypotension associated with beta-blocker toxicity. This study compared combined amrinone and glucagon therapy to glucagon alone and saline control for the treatment of propranolol-induced cardiovascular depression in a canine model. Six animals were pretreated with 10 mg/kg of propranolol intravenously (i.v.), which resulted in significant depression in heart rate (HR), cardiac output (CO), mean arterial pressure (MAP), and maximal left ventricular change in pressure over time (dP/dt max) (P < .0001). Each canine received i.v. amrinone (4 mg/kg) plus glucagon (20 micrograms/kg) therapy during a 2-minute period after propranolol infusion was completed. Cardiovascular parameters were monitored at 1, 6, 11, 21, and 31 minutes after treatment was rendered. Results were compared with those of a previous study, consisting of six animals that received glucagon therapy alone (20 mg/kg) and six controls (normal saline only) in an identical protocol. The addition of i.v. amrinone to glucagon therapy did not increase significantly, HR, CO, stroke volume, or dP/dt max compared with glucagon alone. Total systemic peripheral resistance was reduced significantly during 31 minutes of observation after the administration of combined therapy compared with the control; glucagon alone also reduced systemic peripheral resistance at 1 and 6 minutes. At all time periods except 1 minute of observation there was a significant reduction in MAP when comparing combined therapy with that of glucagon therapy alone. In this model, the addition of amrinone to glucagon therapy seems to have a detrimental effect on the ability of glucagon to increase MAP resulting from propranolol toxicity.

Healthful behaviors: do they protect African-American, urban preadolescents from abusable substance use?

PURPOSE

Relationships between positive health behaviors and abusable substance use in preadolescent, urban, African-American schoolchildren were investigated.

DESIGN

Personal interviews and classroom surveys were used to assess health behavior and abusable substance use cross-sectionally.

SETTING

All respondents resided in the District of Columbia and attended the public school system.

SUBJECTS

The sample consisted of 303 urban, African-American fourth and fifth graders (151 boys, 152 girls).

MEASURES

Classroom surveys assessed drinking, drinking without parental knowledge, smoking, use of other abusable substances, friends' use, self-esteem, and academic performance. Personal interviews assessed children's diet, exercise, overall health behavior, and socioeconomic status.

RESULTS

Logistic regressions showed that children who engaged in more health behaviors (exercise and proper nutrition) were one-third less likely to have smoked (OR=0.66) or to have drunk alcohol (OR=0.63) than those who engaged in fewer healthful activities. However, when gender, socioeconomic status, self-esteem, academic performance, personal use, and friends' use of other abusable substances were controlled, relationships were no longer statistically significant.

CONCLUSIONS

These findings suggest that although positive health behaviors appear to be inversely related to abusable substance use in urban, African-American preadolescents, the relationship may be spurious.

An epidemiologic study of non-occupational lifting as a risk factor for herniated lumbar intervertebral disc. The Northeast Collaborative Group on Low Back Pain

An epidemiologic case-control study of herniated lumbar intervertebral disc was conducted in Springfield, Massachusetts, New Brunswick, New Jersey, and New York, New York, to evaluate the role of several possible risk factors in the etiology of this disorder. Patients with signs and symptoms of herniated lumbar disc (N = 287) were matched to control subjects without back pain by age, sex, source of care, and geographic area. Of the total case-subject group, 177 were confirmed by surgery, computed tomographic scan, myelogram, or magnetic resonance imaging. This article focuses on non-occupational lifting, an activity not previously reported on. Frequent lifting of objects or children weighing 25 or more pounds with knees straight and back bent was associated with increased risk of herniated lumbar disc. This association was particularly strong among confirmed case subjects (relative risk = 3.95). Positive associations among confirmed case subjects were also seen for frequent lifting with arms extended (relative risk = 1.87) and twisting while lifting (relative risk = 1.90). No associations were found for frequent stretching or carrying. If confirmed in other investigations, these data suggest that instruction in lifting techniques should be extended into the home.

The effect of scrubbing and irrigation with normal saline, povidone iodine, and cefazolin on wound bacterial counts in a guinea pig model

This study examines the effects of povidone iodine, normal saline, and cefazolin alone and after scrubbing on bacterial counts in contaminated animal lacerations. Twelve albino guinea pigs each received four lacerations inoculated with a standard inoculum of Staphylococcus aureus. Twelve hours after inoculation, each wound was biopsied to ensure contamination and then either treated or left as an untreated control. One wound on each animal was an untreated control. The remaining three lacerations on six pigs were irrigated with cefazolin (CZ) solution, normal saline, or 1% (wt/vol) povidone iodine solution (PI). Three lacerations on another six pigs were treated with 20% poloxamer 188 scrub (scrub) alone, scrub followed by PI irrigation (SCR/PI), or scrub followed by CZ irrigation (SCR/CZ). Quantitative bacteriology was performed on tissue biopsies 2 hours (time 1), 7 hours (time 2), and 12 hours (time 3) after irrigation. Posttreatment counts for PI, CZ, and normal saline irrigation were not different from control or one another (P > .05). Bacterial counts for SCR/PI were significantly lower than control (P < .05) for all posttreatment biopsies (1.8 to 2.9 mean log(10) decrease). SCR/CZ was significantly lower than control (P < .05) at times 2 and 3 only (1.7 to 2.0 mean log(10) decrease). In this guinea pig model, cleansing 12-hour-old lacerations contaminated with S aureus using SCR/PI or SCR/CZ significantly reduced bacterial counts over 12 hours.

Diazepam versus midazolam for colonoscopy: a prospective evaluation of predicted versus actual dosing requirements

We performed a prospective, randomized, double-blind study to evaluate the efficacy of the currently recommended low doses of midazolam for conscious sedation compared with diazepam for colonoscopy. Each agent was administered in a fixed ratio dose in combination with meperidine, and titrated incrementally to allow for adequate sedation prior to initiating and during the procedure. The currently recommended starting dose of midazolam (0.03 mg/kg) proved to be very appropriate for pre-medication. In contrast, the currently recommended starting dose of diazepam (0.10 mg/kg) proved excessive in 21% of patients (especially in those aged > 65). The low initial and incremental doses of midazolam compared favorably with diazepam in all efficacy parameters studied and exceeded diazepam in post-procedure amnesia scores (p = 0.01). Moreover, the sedative effects of midazolam at these lower doses were not lost despite long duration procedures (> 40 min). We conclude that midazolam, given in small incremental doses, in combination with meperidine, produces effective conscious sedation for colonoscopy and exceeds diazepam in its amnestic effect.

Evidence that local non-NMDA receptors contribute to functional deficits in contusive spinal cord injury

To investigate the role of non-N-methyl-D-aspartate (non-NMDA) types of excitatory amino acid (EAA) receptors in traumatic spinal cord injury, we administered 2,3-dihydroxy-6-nitro-7-sulfamoyl-benzo(F)-quinoxaline (NBQX), a potent and specific antagonist of non-NMDA receptors, to rats with a standardized contusive spinal cord injury. Focal infusion of NBQX into the injury site significantly reduced long-term hindlimb functional deficits as well as decreasing the time required for the rats to establish a reflex bladder. The results suggest that non-NMDA receptors at or near the injury site are involved in producing a portion of the functional deficits that result from contusive spinal cord injury.

A comparison of amrinone and glucagon therapy for cardiovascular depression associated with propranolol toxicity in a canine model

This study's objective is to evaluate the ability of glucagon and amrinone to reverse propranolol induced cardiovascular depression in a canine model, compared to a control of normal saline. The study design included 18 animals which received intravenous propranolol (10 mg/kg) resulting in significant depression in heart rate, cardiac output, mean arterial pressure, maximal ventricular dP/dt and stroke volume. Each canine was randomly assigned to one of three treatment groups; controls (normal saline only), glucagon (20 micrograms/kg bolus) and amrinone (4 mg/kg bolus). Cardiovascular parameters were monitored at 1, 6, 11, 21 and 31 min after treatment was rendered. Multiple comparison procedures at each time period controlled the overall alpha-level at .05. Compared to control animals, both amrinone and glucagon were effective in reversing propranolol-induced depression of dP/dtmax at 6 and 11 min for glucagon and 11 min for amrinone and cardiac output at 1, 6 and 11 min for glucagon and 1 min for amrinone. Amrinone and glucagon significantly increased stroke volume over control values at 1 min and tended to do so at the remaining time periods. The two days caused a similar degree of arteriolar vasodilation which was significantly greater than that seen in control animals at 1 and 6 min. Beta blocker induced bradycardia did not respond significantly to amrinone while glucagon induced a tachycardia which is unique to canines. It is concluded that in this canine model, amrinone appears to be an effective therapeutic alternative to glucagon for reversing depressed dP/dtmax, cardiac output and stoke volume induced by propranolol toxicity. Unlike glucagon, amrinone appears to lack positive chronotropic activity which may limit its clinical utility in the treatment of beta blocker overdose.

Low back pain/prolapsed lumbar intervertebral disc

Low back pain is common throughout the adult years in both men and women; first episodes most frequently occur among people in their 20s and 30s. Prolapsed lumbar disc most often affects individuals in the age range 25-45 years; prolapses occur infrequently in persons below 20 years or over 65 years. Major risk factors for low back pain in general and for prolapsed disc specifically include frequent lifting of objects weighing 25 pounds or more, especially if the objects are lifted with the arms extended and with the knees straight and if the lifting is done while the body is twisted; exposure to whole-body vibration, including driving motor vehicles; cigarette smoking; and, for prolapsed lumbar disc, narrow lumbar vertebral canals. Possible risk factors for which the evidence is weak or inconsistent include frequent stretching, reaching, pulling, and pushing on the job; sedentary occupations; jobs in which workers stay in one position for long periods of time; recent employment in a physically demanding job; jobs requiring frequent twisting without lifting; tallness; heredity; extent of forward flexibility in the lumbar area; lack of physical fitness; pregnancies; psychological symptoms; and frequent participation in bowling. The methods suggested to date with the greatest potential for prevention include modification of jobs so as to reduce exposure to known occupational risk factors, and careful selection of workers by such means as strength testing for the particular job for which they are to be employed.

Outcomes of a geriatric rehabilitation program in a long-term care facility

This study investigated outcomes of geriatric rehabilitation and predictors of success among 81 consecutive admissions to a 40-bed rehabilitation unit in a long-term care facility. Predictors measured at admission included sociodemographic variables, functional status (both current and prior to illness), social contact, and self-motivation. In all, 62 patients (77%) successfully completed the rehabilitation program; 76% of the successes were discharged home. Failure to discharge successfully rehabilitated subjects was mainly due to placement problems and patient and family preference. Both of the success groups showed significant improvement in functional status (Barthel Index), while failures had poorer initial functional status, and showed no improvement on average. At six-month follow-up, functional status (measured by the Sickness Impact Profile) was similar in the two success groups. No predictors other than functional status were associated with rehabilitation success. Among the successes, better functional status at six months was predicted by aspects of self-motivation.

Intensive care unit patient follow-up. Mortality, functional status, and return to work at six months

Six months after hospital discharge, we followed up 1545 patients who had received care in the general medical-surgical intensive care unit (ICU) of a tertiary care hospital. Vital status could not be ascertained for 200 of these patients. Of the 1345 former ICU patients for whom a determination of vital status could be made, 1261 (94%) were alive and 84 (6%) had died. Of those known to be living, 887 (70%) responded to a questionnaire regarding employment, functional, and social status. A large proportion of survivors less than 40 years of age had returned to work. Younger patients admitted to the hospital for elective surgery reported as much compromise of physical and psychological activity as did older patients admitted for emergency reasons. Older survivors reported an increase of interaction with family members and a decrease of social interaction with those other than family.