The neuropsychiatry of carbon monoxide poisoning in attempted suicide: a prospective controlled study

The occurrence of delayed neuropsychologic sequelae in acute carbon monoxide poisoning patients after treatment with hyperbaric or normobaric oxygen therapy

This study aimed at assessing which one of the 2 therapies is better for treating carbon monoxide (CO) poisoning from the perspective of reducing delayed neuropsychologic sequelae (DNS).We used Taiwan's National Health Insurance Research Database (NHIRD) to conduct a nationwide population-based cohort study to assess which therapy is better for CO poisoning patients. To accurately identify patients with DNS, the definition of DNS is included neurological sequelae, and cognitive and psychological sequele. The independent variable was therapy and the dependent variable was DNS occurred within 1 year after discharge from a medical institution. The control variables were age, gender, the severity of CO poisoning, and comorbidities present before CO poisoning admission.The risk of developing DNS in patients treated with Hyperbaric Oxygen (HBO) was 1.87-fold (P < .001) than normobaric oxygen (NBO) therapy. The severity of CO poisoning and comorbidities were also found to have significant influences on the risk of developing DNS.HBO may be a risk therapy for treating CO poisoning.

Neuroimaging, Cognitive, and Neurobehavioral Outcomes Following Carbon Monoxide Poisoning

Carbon monoxide is a colorless, odorless gas produced as a byproduct of combustion. Carbon monoxide is the leading cause of poisoning injury and death worldwide. Morbidity following CO poisoning includes neurologic sequelae, neuropathologic abnormalities on brain imaging, neurobehavioral changes, and cognitive impairments. It is estimated that as high as 50% of individuals with carbon monoxide poisoning will develop neurologic, neurobehavioral, or cognitive sequelae. Carbon monoxide related cognitive impairments included impaired memory, attention, executive function, motor, visual spatial, and slow mental processing speed. Given the high rate of brain related morbidity and the fact that the majority of carbon monoxide is avoidable, awareness and prevention of carbon monoxide poisoning is warranted.

Neuropsychological Evaluation of Children and Adolescents With Acute Carbon Monoxide Poisoning

OBJECTIVES

Carbon monoxide (CO) poisoning is a worldwide health problem. We have limited information regarding psychological adversities of CO poisoning in children and adolescents. The aim of this study was (1) to investigate the effects of severe CO poisoning on cognitive functions, mood, and behaviors in children and adolescents and (2) to identify factors related to occurrence of neuropsychological symptoms.

METHODS

This study included pediatric patients, who were evaluated after CO poisoning at the Department of Child and Adolescent Psychiatry between January 2012 and April 2013. The patients were evaluated at 2 time points. The first evaluation was done when they were discharged from emergency department, and the second evaluation was done 1 month after CO poisoning. Turkish versions of internationally recognized tests were used to evaluate anxiety, depressive symptoms, attention, visual-spatial skills, memory, and behaviors of patients.

RESULTS

Twenty-seven patients were analyzed. The mean age of the patients was 11.8 ± 2.7 years (range, 6-18 years). The mean carboxyhemoglobin level was 31.5% ± 7.8% (range, 19%-51%) dir. Delayed neurological sequel was observed in only 1 patient, who had headache and tinnitus. We found that carboxyhemoglobin level was not correlated with later neuropsychiatric test scores. However, we found a correlation between history of loss of consciousness and anxiety symptom level, hyperbaric oxygen (HBO) therapy session and behavioral problems, and time to HBO therapy and attention problems.

CONCLUSIONS

We suggest that CO exposure duration, history of loss of consciousness, time to HBO therapy, and the number of HBO therapy session affect neuropsychological symptom levels and occurrence of attention and behavioral problems.

Analysis of patients presenting to the emergency department with carbon monoxide intoxication

OBJECTIVES

Carbon monoxide is a potentially fatal form of poisoning. The exact incidence is unclear, due to cases being undiagnosed or reported as fewer than the real number. Hyperbaric oxygen therapy (HBOT) is of proven efficacy in the treatment of CO intoxication. The purpose of this study was to describe the general characteristics of carbon monoxide (CO) intoxications presenting to the emergency department and to investigate troponin I values and the effectiveness of hyperbaric oxygen therapy (HBOT) in these patients.

MATERIAL AND METHODS

Patients presenting to the emergency department with CO intoxication over one year and patients with such intoxications receiving HBOT were examined retrospectively.

RESULTS

One hundred seventy-one patients were included; 140 (81.9%) were poisoned by stoves, 18 (10.5%) by hot water boilers and 10 in (5.8%) by fires. COHb levels were normal in 49 of the 163 patients whose values were investigated, and were elevated in 114 patients. Mean COHb value was 16.6. Troponin I values were investigated in 112 patients. These were normal in 86 patients and elevated in 26. Mean troponin I value was 0.38 ng/ml. One hundred twenty-three of the 171 patients in the study were discharged in a healthy condition after receiving normobaric oxygen therapy, while 48 patients received HBOT. Forty-two (87.5%) of the patients receiving HBOT were discharged in a healthy condition while sequelae persisted in five (10.4%). One patient died after 15 session of HBOT.

CONCLUSION

Although elevated carboxyhemoglobin confirms diagnosis of CO intoxication, normal levels do not exclude it. Troponin I levels may rise in CO intoxication. No significant relation was observed between carboxyhemoglobin and receipt of HBOT. A significant correlation was seen, however, between troponin I levels and receipt of HBOT.

Executive function and suicidality: A systematic qualitative review

Deficits in executive function (EF) have been proposed as a possible explanation for the "cognitive rigidity" often observed in suicidal individuals. This article provides a systematic review of the existing literature testing the relations between EF and suicidality, across various diagnostic and demographic populations, using the influential multidimensional model of EF proposed by Miyake and colleagues (2000) as an organizing framework. Forty-three journal articles on this topic published before January of 2014 were reviewed. Collectively, results from these studies provide tentative support for an association between EF deficits and suicidality. However, there is some evidence that this association is moderated by other factors (e.g., suicide attempt lethality). Importantly, this relationship may vary across diagnostic groups. Specifically, more studies that used depressive disorder samples reported some positive findings (75%), followed by mixed diagnostic samples (54%). In contrast, fewer positive findings have emerged from studies with bipolar or psychotic disorder samples (29% and 33% respectively), and some even found that suicidality is associated with better EF in individuals with psychotic disorders. Firm conclusions about relationships between specific dimensions of EF and/or aspects of suicidality are difficult to draw this time. Limitations of the existing literature and corresponding directions for future research are discussed.

Longitudinal changes in the dopamine transporter and cognition in suicide attempters with charcoal burning

Suicide with charcoal burning, which results in carbon monoxide (CO) poisoning, is common in Asia. This study was designed to elucidate associations between changes in the dopamine transporter (DAT) and cognitive function in patients following CO poisoning during a follow-up period of 6 months. Participants comprised 31 healthy controls (HCs) and 21 CO poisoning patients. Each subject underwent single photon emission computed tomography with [(99m)Tc] TRODAT-1 to measure DAT availability and completed a cognitive battery assessing attention, memory, and executive function. For CO poisoning patients, a second DAT measurement and repeated cognitive evaluations were performed 6 months later. At baseline, DAT availability over bilateral striatum in CO poisoning subjects was significantly lower than in HCs. After 6 months, there was no significant change of DAT availability in CO poisoning patients. CO poisoning patients also had worse cognitive performance in all domains compared with HCs at baseline. After 6 months, most cognitive functions were significantly improved, except for the Wisconsin Card Sorting Test (WCST), a measure of executive function. Interestingly, changes in the WCST were significantly correlated with changes in DAT availability during the 6-month follow-up period. The persistence of reduced DAT availability and its association with impaired performance on the WCST indicate a crucial role of DAT in the recovery of executive function following CO poisoning.

Neuropsychiatric disorders and risk factors in carbon monoxide intoxication

Neuropsychiatric sequelae may be observed in the late phases of carbon monoxide (CO) intoxication. Establishing a link between CO-related neuropsychiatric disorders and associated risk factors may decrease morbidity and mortality by means of appropriate treatment and counseling. The aim of the present study was to determine the relationship between neuropsychiatric outcomes of CO intoxication and demographic and clinical variables. Thirty patients who presented with CO intoxication and had no known neuropsychiatric disease, and 30 healthy controls were included. Physical examinations and laboratory tests were performed. Following the 1st therapy, they underwent mental and psychiatric tests 5 times (the time of discharge, during the 1st week, and during the 1st, 3rd, and 6th months). They underwent cerebral magnetic resonance imaging (MRI) at the end of the 1st month. They were evaluated by cognitive function tests at the 6th month. Lesions relevant to CO intoxication were detected in 46.7% of the patients via cranial computed tomography and in 13.3% via MRI. Evaluation of psychiatric tests revealed a clear decrease in cognitive functions, such as immediate memory, learning, reaching the criterion, spontaneous recall, attention, visual memory, and logical memory. It was found that the patients had anxiety within the 1st month, and the frequency of anxiety reached to the value of the control group by the end of the 6th month. In conclusion, we suggested that CO intoxication might lead to neuropsychiatric disorders. Our results emphasized that in addition to standard treatment, neuropsychiatric evaluation should also be performed in patients with CO intoxication.

Predictors of carbon monoxide poisoning-induced delayed neuropsychological sequelae

OBJECTIVE

Carbon monoxide poisoning (COP) commonly results in delayed neuropsychological sequelae (DNS). The aim of the article is to demonstrate the clinical characteristics and potential predictors of COP-induced DNS later.

METHOD

Retrospective medical record review was performed for patients who had COP in the past year at a National Medical Center in Taiwan. Sixty patients with COP were registered during a one-year period. Fifty-six of them (93.3%) were COP because of suicide attempt. Patients with COP who have a complete medical record of carboxyhemoglobin (COHb) and Glasgow Coma Scale (GCS) and Mini-Mental Status Examination (MMSE) scores were recruited. Multiple regression analysis was performed to search for the predictive factors of DNS.

RESULTS

Forty-three patients were recruited. Most had attempted suicide (93.0%) using CO, and thirteen developed DNS later. A longer duration of admission, more sessions of hyperbaric oxygen therapy, and positive findings in brain computed tomography (CT) scans were more often found in patients with DNS than those without DNS. The GCS and MMSE scores and positive findings in brain CT scans were associated with the development of DNS but COHb was not.

CONCLUSIONS

Our results identified several potential predictors of DNS. This finding may help clinicians understand and treat COP patients efficiently.

Neurologic and radiologic manifestations of three girls surviving acute carbon monoxide poisoning

We report the neurologic and radiologic manifestations of three adolescent girls with acute carbon monoxide poisoning. The girls were found collapsed and unconscious in a bathroom where liquid petroleum gas was being used as heating fuel. As hyperbaric oxygen therapy was not available locally, they only received oxygen supplementation via nasal cannula (4 L/minute) as treatment in the first 2 days. On transfer to a tertiary center in Hong Kong, evolving neurologic manifestations of visual acuity and field deficits, confusion, and focal motor weaknesses were observed. Focal infarctions were evident in cerebral computed tomography in one patient and cortical lesions on magnetic resonance imaging in all three patients. [18F]Fluorodeoxyglucose (FDG) positron emission tomography (PET) revealed additional decreased metabolism in the basal ganglia in two patients, which was typical of carbon monoxide poisoning. The neurologic deficits resolved completely at 3 weeks after the exposure, but psychologic symptoms succeeded. This report serves to alert clinicians to the varied neuro-ophthalmologic manifestations and psychologic impairment even with the same duration of carbon monoxide poisoning. PET might be more sensitive in detecting cerebral injuries specific for carbon monoxide poisoning.

Toxicity Associated with Carbon Monoxide

Carbon monoxide is an insidious poison that accounts for thousands of deaths each year in North America. Clinical effects maybe diverse and include headache, dizziness, nausea, vomiting,syn-cope, seizures, coma, dysrhythmias, and cardiac ischemia. Children, pregnant women, and patients who have underlying cardiovascular disease are particularly at risk for adverse out-comes. Treatment consists of oxygen therapy, supportive care, and, in selected cases, hyperbaric oxygen therapy.

Carbon monoxide poisoning

CO is an ubiquitous poison with many sources of exposure. CO poisoning produces diverse signs and symptoms that are often subtle and may be easily misdiagnosed. Failure to diagnose CO poisoning may result insignificant morbidity and mortality and permit continued exposure to a dangerous environment. Treatment of CO poisoning begins with inhalation of supplemental oxygen and aggressive supportive care. HBOT accelerates dissociation of CO from hemoglobin and may also prevent DNS. Absolute indications forHBOT for CO poisoning remain controversial, although most authors would agree that HBOT is indicated in patients who are comatose or neurologically abnormal, have a history of LOC with their exposure, or have cardiac dysfunction. Pregnancy with an elevated CO-Hgb level(>15%-20%) is also widely, considered an indication for treatment.HBOT may be considered in patients who have persistent symptoms despite NBO, metabolic acidosis, abnormalities on neuropsychometric testing, or significantly elevated levels. The ideal regimen of oxygen therapy has yet to be determined, and significant controversy exists regarding HBOTtreatment protocols. Often the local medical toxicologist, poison control center, or hyperbaric unit may assist the treating physician with decisions regarding therapy.

Affective outcome following carbon monoxide poisoning: a prospective longitudinal study

OBJECTIVE

To longitudinally assess the prevalence of depression and anxiety following carbon monoxide (CO) poisoning and to assess the contributions of mode of poisoning (accidental versus suicide attempt), cognitive sequelae, and oxygen dose (hyperbaric oxygen versus normobaric oxygen) to depression and anxiety.

BACKGROUND

CO is the most common cause of poisoning in the United States and may result in neuropathologic changes and cognitive and neurologic sequelae, yet little is known regarding affective outcomes.

METHOD

We prospectively assessed affect in 127 CO-poisoned patients. Self-report inventories of depression and anxiety were administered at 6 weeks and at 6 and 12 months post CO poisoning. The primary outcome was prevalence of depression and anxiety at 6 weeks. To determine the effect of mode of poisoning, cognitive sequelae, and oxygen dose, odds ratio estimates were calculated at all three times using logistic regression.

RESULTS

Depression and anxiety were present in 45% of patients at 6 weeks, 44% at 6 months, and 43% at 12 months. Patients with suicide attempt and cognitive sequelae had higher prevalence of depression and anxiety at 6 weeks. At 12 months, there were no differences in depression or anxiety regardless of mode of poisoning, presence of cognitive sequelae, or oxygen dose.

CONCLUSIONS

CO poisoning results in significant depression and anxiety that persist to at least 12 months. Patients with cognitive sequelae and suicide attempt had a higher rate of depression and anxiety at 6 weeks but not at 12 months. Clinicians need to be aware of affective morbidity following CO poisoning and remain vigilant about CO prevention.

Anoxic Versus Traumatic Brain Injury: Amount of Tissue Loss, Not Etiology, Alters Cognitive and Emotional Function

Research in neuropsychology suggests that the etiology of a neurologic injury determines the neuropathological and neuropsychological changes. This study compared neuropsychological outcome in subjects who had traumatic brain injury (TBI) with subjects who had anoxic brain injury (ABI), who were matched for age, gender, and ventricle-to-brain ratio. There were no group differences for morphologic or neuropsychological measures. Both groups exhibited impaired memory, attention, and executive function, as well as slowed mental processing speed. Intelligence correlated with whole brain volume, and measures of memory correlated with hippocampal atrophy. There was no unique contribution of hippocampal atrophy on neuropsychological outcome between the groups. In the absence of localized lesions, the amount of neural tissue loss, rather than etiology, may be the critical factor in neuropsychological outcome.

Carbon monoxide poisoning

CO is an insidious poison with many sources of exposure. CO poisoning produces diverse signs and symptoms, which often are subtle and can be misdiagnosed easily. Failure to diagnose CO poisoning may result insignificant morbidity and mortality and allow continued exposure to a dangerous environment. In the ED, a high index of suspicion must be maintained for occult CO exposure. Headache, particularly when associated with certain environments, and flulike illness in the wintertime with symptomatic cohabitants should raise the index of suspicion in the ED significantly for occult CO poisoning. Emergency treatment of CO poisoning begins with inhalation of supplemental oxygen and aggressive supportive care. HBOT accelerates dissociation of CO from hemoglobin and may prevent DNS. Absolute indications for HBOT for CO poisoning remain controversial, although most would agree that HBOT is indicated in patients who are comatose, are neurologically abnormal, have a history of loss of consciousness with their exposure, or have cardiac dysfunction. Pregnancy with an elevated CO-Hgb level (>15-20%) also is widely considered an indication for treatment. HBOT may be considered in patients who have persistent symptoms despite NBO, metabolic acidosis, abnormalities on neuropsychometric testing, or significantly elevated levels. The ideal regimen of oxygen therapy has yet to be determined, and significant controversy exists regarding HBOT protocols. The emergency physician may be confronted with the difficult decision regarding disposition and even transfer to a hyperbaric facility. Often the local medical toxicologist, poison control center, or hyperbaric unit can assist the emergency physician with the decision-making process.