Comparison of four low-level carbon monoxide alarms suitable for home use or when traveling.

Introduction: Interest in carbon monoxide (CO) alarms that are more sensitive than is required for standard residential CO alarms is growing, as reflected by increased marketing of "low-level" alarms capable of measuring CO levels as low as 10 PPM. At the same time, publicity surrounding CO poisoning events among travelers in lodging facilities has stimulated interest in travel CO alarms. We sought to evaluate four low-level alarms that could be used in the home and especially when traveling. Materials/Methods: Two each of four brands of low-level alarms (CO Experts, Forensics, Kidde, and Sensorcon) were acquired by retail purchase and tested. The eight alarms were simultaneously exposed in an environment with a slowly increasing level of CO from indoor burning of charcoal briquets. CO levels displayed on the alarms were recorded once per minute. Activation of preset alerts on the alarms were noted. Finally, alarms were compared for ease of use and features available.. Results: All brands of alarms measured CO similarly over the range from 10-120 PPM. All alarms performed as claimed by their manufacturers, both regarding range of CO reported and preset alert activation. Each alerted at CO levels below that required by the Underwriters Laboratories 2034 Standard. Summary/Conclusion: Since all low-level CO alarms tested measured CO similarly, consumers seeking a low-level CO alarm for use while traveling should base their decision on features desired and price. There are definite differences between the alarms tested, in terms of features, expected durability, ease of operation and price.

Preventing carbon monoxide poisoning in the Hudson River Tunnel in 1921: recounting history.

The New York Bridge and Tunnel Commission began planning for a tunnel beneath the lower Hudson river to connect Manhattan to New Jersey in 1919. At 8,300 feet, it would be the longest tunnel for passenger vehicles in the world. A team of engineers and physiologists at the Yale University Bureau of Mines Experiment Station was tasked with calculating the ventilation requirements that would provide safety from exposure to automobile exhaust carbon monoxide (CO) while balancing the cost of providing ventilation. As the level of ambient CO which was comfortably tolerated was not precisely defined, they performed human exposures breathing from 100 to 1,000 ppm CO, first on themselves and subsequently on Yale medical students. Their findings continue to provide a basis for carbon monoxide alarm requirements a century later.

Carbon monoxide poisoning while scuba diving: a rare event?

Contamination of breathing gas is a risk for all divers. Some hydrocarbon contaminants will be sensed by the diver and the dive profile aborted. On the contrary, carbon monoxide may not be recognized by the diver and catastrophic consequences can result. Reported here is the fatal case of carbon monoxide poisoning while scuba diving, an event that has rarely been reported in the medical literature. A detailed review of other published cases of CO poisoning while scuba diving is included, attempting to identify causes in common and propose methods of prevention.

Racial and ethnic trends in unintentional carbon monoxide poisoning deaths.

OBJECTIVE: Government programs have attempted to impact a recognized elevated risk for carbon monoxide (CO) poisoning among minority racial and ethnic groups. This study sought to describe U.S. mortality due to unintentional, non-fire-related CO poisoning, examining the distribution and trends by race and ethnicity. METHODS: CDC Wonder was used to extract and analyze data on all U.S. resident deaths from unintentional CO poisoning from 2000-2017, categorizing them by year, race, ethnic origin and gender. RESULTS: The absolute number of unintentional CO deaths decreased from about 450 to 380 per year during the period studied, a number near totally accounted for by the decrease in deaths occurring among non-Hispanic/Latino whites. The number of deaths among the remainder of the population did not significantly change. However, greater growth in minority populations resulted in a similar decline in the mortality rate between non-Hispanic/Latino whites and the combined minority population. The decline in combined minority death rate resulted from a decrease in the Hispanic/Latino white rate. Death rate did not decline in the black or African American population. CONCLUSIONS: All minority groups continue to display a disproportionate number of unintentional non-fire-related CO poisoning deaths compared to non-Hispanic/Latino whites. The decrease in U.S. deaths from unintentional non-fire-related carbon monoxide poisoning from 2000-2017 is accounted for by a decrease in non-Hispanic/Latino white deaths. While numbers of such deaths among minority groups have not changed since 2000, increases in the size of minority populations have resulted in a declining crude death rate for Hispanic/Latino whites.

Carboxyhemoglobin: a primer for clinicians.

One of carbon monoxide's several mechanisms of toxicity is binding with circulating hemoglobin to form carboxyhemoglobin, resulting in a functional anemia. While patients with carbon monoxide poisoning are often said to be "cherry-red," such discoloration is rarely seen. Carboxyhemoglobin levels cannot be measured with conventional pulse oximetry, can be approximated with pulse CO-oximetry, and are most accurately measured with a laboratory CO-oximeter. Carboxyhemoglobin levels are quite stable and can be accurately measured on a transported blood sample. For clinical purposes, arterial and venous carboxyhemoglobin levels can be considered to be equivalent. Carboxyhemoglobin levels are typically lower than 2% in non-smokers and lower than 5% in smokers. A level over 9% is almost always due to exogenous carbon monoxide exposure, even among smokers. Conversely, a low level does not exclude significant exposure under certain circumstances. As carboxyhemoglobin levels of poisoned patients do not correlate with symptoms or outcome, their greatest utility is a marker of exposure.

Prospective evaluation of pulmonary function in Parkinson's disease patients with motor fluctuations.

BACKGROUND: Spirometry patterns suggesting restrictive and obstructive pulmonary dysfunction have been reported in Parkinson's disease (PD). However, the patterns' precise relation to PD pathophysiology remains unclear. Purpose/Aim. To assess ON- versus OFF-state pulmonary function, the quality of its spirometric evaluation, and the quality of longitudinal spirometric findings in a large sample of PD patients with motor fluctuations. METHODS: During a placebo-controlled trial of an inhaled levodopa formulation, CVT-301, in PD patients with ≥2 h/d of OFF time, spirometry was performed by American Thoracic Society (ATS) guidelines at screening and throughout the 4-week treatment period. RESULTS: Among 86 patients, mean motor impairment during an OFF state at screening was moderately severe. However, mean spirometry results at screening were within normal ranges, and in a mixed model for repeated measures (MMRM), the results at screening were not dependent on motor state (ON vs. OFF). In the placebo group (n = 43), 76% of ON-state and 81% of OFF-state examinations throughout the study met ATS quality metrics, and in an MMRM analysis, mean findings at these patients' arrivals for treatment-period visits showed no significant 4-week change. Across all 86 patients, flow-volume curves prior to any study-drug administration showed only a 3% incidence of "sawtooth" morphology. CONCLUSIONS: In PD patients with motor fluctuations, longitudinal spirometry of acceptable quality was generally obtained. Although mean findings were normal, about a quarter of spirograms did not meet ATS quality criteria. Spirogram morphology may be less indicative of various forms of respiratory dysfunction than has previously been reported in PD.

Cost effectiveness of residential carbon monoxide alarms.

BACKGROUND: While residential carbon monoxide (CO) alarms are now required in a majority of states, the cost effectiveness of the devices is unknown. This analysis was performed to determine the degree of prevention efficacy necessary from home carbon monoxide alarms for their expense to be cost-effective. METHODS: Data regarding numbers of individuals affected in the United States annually from accidental, non-fire, residential non-fatal and fatal carbon monoxide poisoning were obtained from published literature. Federal governmental estimates of societal costs associated with medical care, lost wages and earnings, value of pain and suffering, and value of a statistical life were applied. The cost of uniform residential carbon monoxide alarm installation was compared to those societal costs in order to calculate what degree of efficiency makes alarms cost-effective. RESULTS: Societal costs for accidental, non-fire, residential CO poisoning are approximately $3.47 billion annually. With an estimated cost of $348 million annually for alarms, prevention of greater than 10% of residential CO poisoning costs must be achieved in order for alarms to be cost-effective. CONCLUSIONS: While the true effectiveness of residential carbon monoxide alarms has yet to be determined, current state legislation requiring residential installation of CO alarms is probably cost-effective. .

Comparison of normobaric vs. hyperbaric oxygen in the relief of carbon monoxide headache pain.

BACKGROUND: Headache is the most common symptom in carbon monoxide (CO) poisoning. While the mechanism of CO-induced headache is not well defined, it is felt that cerebral vasodilation plays a role. Clinical experience has demonstrated oxygen breathing is effective in resolving CO headache. However, the effectiveness of normobaric oxygen has never been compared to hyperbaric oxygen in this regard. METHODS: A 2016 paper by Ocak, et al. reported the response of CO headache pain severity to four hours of normobaric oxygen breathing in 82 patients using a 0-10 analog scale. The demographics, carboxyhemoglobin levels and response to therapy from that report were compared to data obtained by Hampson, et al. in an earlier study, but never published, using the same pain assessment method in 73 patients with CO headache and treated with hyperbaric oxygen. RESULTS: Comparing the normobaric and hyperbaric groups, neither average age nor presenting carboxyhemoglobin levels were significantly different. Baseline pain intensity scores were 6.5 ± 3.1 vs. 6.2 ± 2.6 (p=0.444) and post-treatment scores 1.5 ± 2.6 vs. 1.0 ± 1.5 (p=0.184) respectively on a 0-10 scale. CONCLUSIONS: In these two well-matched populations of patients with CO-induced headache pain, degree of resolution was not significantly different between normobaric and hyperbaric oxygen treatment.

Garage carbon monoxide levels from sources commonly used in intentional poisoning.

BACKGROUND: The incidence of intentional carbon monoxide (CO) poisoning is believed to have declined due to strict federal CO emissions standards for motor vehicles and the uniform application of catalytic converters (CC). We sought to compare ambient CO levels produced by automobiles with and without catalytic converters in a residential garage, as well as from other CO sources commonly used for intentional poisoning. METHODS: CO levels were measured inside a freestanding 73 m3 one-car garage. CO sources included a 1971 automobile without CC, 2003 automobile with CC, charcoal grill, electrical generator, lawn mower and leaf blower. RESULTS: After 20 minutes of operation, the CO level in the garage was 253 PPM for the car without a catalytic converter and 30 PPM for the car equipped withone. CO levels after operating or burning the other sources were: charcoal 200 PPM; generator >999 PPM; lawn mower 198 PPM; and leaf blower 580 PPM. CONCLUSIONS: While emissions controls on automobiles have reduced intentional CO poisonings, alternate sources may produce CO at levels of the same magnitude as vehicles manufactured prior to the use of catalytic converters. Those involved in the care of potentially suicidal individuals should be aware of this.

Another perspective on ACEP policy on critical issues in carbon monoxide poisoning: Invited commentary.

The American College of Emergency Physicians (ACEP) recently published its official policy on the evaluation and management of patients with acute carbon monoxide (CO) poisoning [1], an update of the policy previously published in 2008. Three questions regarding CO poisoning were posed to a 30-person ACEP subcommittee, which employed a comprehensive literature review to attempt to draw conclusions. While this is a major step forward, we feel that their conclusions warrant comment.

A randomized trial of inhaled levodopa (CVT-301) for motor fluctuations in Parkinson's disease.

BACKGROUND: Although levodopa is the most effective oral PD therapy, many patients experience motor fluctuations, including sudden loss of dose effect and delayed benefit. CVT-301 is a levodopa inhalation powder with the potential for rapid onset of action. The objective of this study was to evaluate CVT-301 self-administered by PD patients to relieve OFF episodes. METHODS: PD patients with ≥2 hours per day of OFF time despite oral levodopa ≥4 times per day were randomized to CVT-301 or placebo for 4 weeks, to be used up to 3 times per day for OFF episodes. After 2 weeks, the study-drug dose was escalated from 35 to 50 mg. The primary end point was mean change in UPDRS Part III score from a predose OFF state to the average of postdose scores obtained at 10, 20, 30, and 60 minutes, as assessed in-clinic at the end of week 4. Home diaries were recorded. RESULTS: Eighty-six patients used the study drug at an average frequency of 2.1 times per day for CVT-301 and for placebo. At 4 weeks, least-squares mean change in UPDRS Part III score favored CVT-301 by 7.0 points (P < 0.001). A treatment effect was evident at 10 minutes. At 4 weeks, least-squares mean OFF-time change from baseline favored CVT-301 by 0.9 hours per day (P = 0.045). The most frequently reported adverse events in the CVT-301 group were dizziness, cough, and nausea, each in 7% (3 of 43 patients). CONCLUSIONS: CVT-301 self-administered during OFF episodes provided rapid improvement of motor function, and daily OFF time was significantly reduced at the higher dose. CVT-301 was generally safe and well-tolerated. © 2016 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Hyperbaric oxygen therapy for late radiation tissue injury.

BACKGROUND: Cancer is a significant global health problem. Radiotherapy is a treatment for many cancers and about 50% of people having radiotherapy will be long-term survivors. Some will experience late radiation tissue injury (LRTI) developing months or years later. Hyperbaric oxygen therapy (HBOT) has been suggested as a treatment for LRTI based upon the ability to improve the blood supply to these tissues. It is postulated that HBOT may result in both healing of tissues and the prevention of problems following surgery. OBJECTIVES: To assess the benefits and harms of HBOT for treating or preventing LRTI. SEARCH METHODS: We updated the searches of the Cochrane Central Register of Controlled Trials (CENTRAL; 2015, Issue 11), MEDLINE, EMBASE, DORCTIHM and reference lists of articles in December 2015. We also searched for ongoing trials at clinicaltrials.gov. SELECTION CRITERIA: Randomised controlled trials (RCTs) comparing the effect of HBOT versus no HBOT on LRTI prevention or healing. DATA COLLECTION AND ANALYSIS: Three review authors independently evaluated the quality of the relevant trials using the guidelines of the Cochrane Handbook for Systematic Reviews of Interventions and extracted the data from the included trials. MAIN RESULTS: Fourteen trials contributed to this review (753 participants). There was some moderate quality evidence that HBOT was more likely to achieve mucosal coverage with osteoradionecrosis (ORN) (risk ratio (RR) 1.3; 95% confidence interval (CI) 1.1 to 1.6, P value = 0.003, number needed to treat for an additional beneficial outcome (NNTB) 5; 246 participants, 3 studies). There was also moderate quality evidence of a significantly improved chance of wound breakdown without HBOT following operative treatment for ORN (RR 4.2; 95% CI 1.1 to 16.8, P value = 0.04, NNTB 4; 264 participants, 2 studies). From single studies there was a significantly increased chance of improvement or cure following HBOT for radiation proctitis (RR 1.72; 95% CI 1.0 to 2.9, P value = 0.04, NNTB 5), and following both surgical flaps (RR 8.7; 95% CI 2.7 to 27.5, P value = 0.0002, NNTB 4) and hemimandibulectomy (RR 1.4; 95% CI 1.1 to 1.8, P value = 0.001, NNTB 5). There was also a significantly improved probability of healing irradiated tooth sockets following dental extraction (RR 1.4; 95% CI 1.1 to 1.7, P value = 0.009, NNTB 4).There was no evidence of benefit in clinical outcomes with established radiation injury to neural tissue, and no randomised data reported on the use of HBOT to treat other manifestations of LRTI. These trials did not report adverse events. AUTHORS' CONCLUSIONS: These small trials suggest that for people with LRTI affecting tissues of the head, neck, anus and rectum, HBOT is associated with improved outcome. HBOT also appears to reduce the chance of ORN following tooth extraction in an irradiated field. There was no such evidence of any important clinical effect on neurological tissues. The application of HBOT to selected participants and tissues may be justified. Further research is required to establish the optimum participant selection and timing of any therapy. An economic evaluation should be undertaken.

Myth busting in carbon monoxide poisoning.

The evidence supporting many beliefs in medicine is based upon opinion, personal experience, hearsay, or "common knowledge." When one searches for the data supporting oft-quoted facts in medicine, they are sometimes found to be old, incorrect, or nonexistent. Such unsupported facts or beliefs can be termed myths. This minireview will summarize 4 examples of "myth busting" by the author when he has discovered widely held beliefs regarding carbon monoxide (CO) poisoning to be untrue during a 25-year career of research in the field. These include the mistaken beliefs that (1) symptoms correlate with presenting blood carboxyhemoglobin levels, (2) residents are safe from CO poisoning if their home does not contain fuel-burning appliances, (3) carboxyhemoglobin levels must be measured rapidly and on arterial blood, and (4) CO poisoning predisposes to premature long-term death from cardiac disease. In addition to providing the evidence disproving these myths, the importance of going back to the original reference when citing prior work is emphasized.

Carbon Monoxide Poisoning from Portable Electrical Generators.

BACKGROUND: Portable electrical generators have been responsible for over 800 accidental carbon monoxide (CO) poisoning deaths in the United States from 1999-2012. OBJECTIVES: Because mortality figures are typically the only data reported with regard to the adverse effects of generators, we describe a nonfatal segment of the poisoned population to further emphasize the significance of the problem. METHODS: Unidentifiable information about patients treated in the United States with hyperbaric oxygen for acute CO poisoning was prospectively reported by participating centers. Those patients poisoned by portable generators were selected for analysis. RESULTS: Of 1604 patients reported from August 1, 2008 to July 31, 2011, there were 264 accidentally poisoned by portable generators. Exposures occurred in 151 incidents in 33 states. In 99 incidents, poisoning occurred in a residence. Average patient age was 37 ± 20 years (range 1 to 90+ years). Of those poisoned, 146 (55%) were non-Hispanic white, 57 (22%) were black, 52 (20%) were Hispanic white, 4 (2%) were Asian, and 4 (2%) were Native American. English was spoken by 96%. The most common symptoms included headache (62%), dizziness (52%), and loss of consciousness (50%). Blood carboxyhemoglobin levels averaged 22.7 ± 9.0% (range 2.3-48.3%). Thirty-six patients demonstrated evidence of cardiac ischemia. CONCLUSIONS: Acute, severe CO poisoning from portable electric generators is common in the United States, likely affecting an estimated 4000 individuals annually, occurring predominantly in residential settings, and affecting English language-speaking individuals.