Are arterial blood gases of value in treatment decisions for carbon monoxide poisoning?

Carbon Monoxide as a Potential Therapeutic Agent: A Molecular Analysis of Its Safety Profiles

Carbon monoxide (CO) is endogenously produced in mammals, with blood concentrations in the high micromolar range in the hemoglobin-bound form. Further, CO has shown therapeutic effects in various animal models. Despite its reputation as a poisonous gas at high concentrations, we show that CO should have a wide enough safety margin for therapeutic applications. The analysis considers a large number of factors including levels of endogenous CO, its safety margin in comparison to commonly encountered biomolecules or drugs, anticipated enhanced safety profiles when delivered via a noninhalation mode, and the large amount of safety data from human clinical trials. It should be emphasized that having a wide enough safety margin for therapeutic use does not mean that it is benign or safe to the general public, even at low doses. We defer the latter to public health experts. Importantly, this Perspective is written for drug discovery professionals and not the general public.

"CO in a pill": Towards oral delivery of carbon monoxide for therapeutic applications

Along with the impressive achievements in understanding the endogenous signaling roles and mechanism(s) of action of carbon monoxide (CO), much research has demonstrated the potential of using CO as a therapeutic agent for treating various diseases. Because of CO's toxicity at high concentrations and the observed difference in toxicity profiles of CO depending on the route of administration, this review analyzes and presents the benefits of developing orally active CO donors. Such compounds have the potential for improved safety profiles, enhancing the chance for developing CO-based therapeutics. In this review, the difference between inhalation and oral administration in terms of toxicity, CO delivery efficiency, and the potential mechanism(s) of action is analyzed. The evolution from CO gas inhalation to oral administration is also extensively analyzed by summarizing published studies up to date. The concept of "CO in a pill" can be achieved by oral administration of novel formulations of CO gas or appropriate CO donors.

Cyanide: critical issues in diagnosis and treatment

The concern of a terrorist attack using cyanide, as well as the gradual awareness of cyanide poisoning in fire victims, has resulted in a renewed interest in the diagnosis and treatment of cyanide poisoning. The formerly academic presentation of cyanide poisoning must be replaced by more useful knowledge, which will allow emergency physicians and rescue workers to strongly suspect cyanide poisoning at the scene. Human cyanide poisonings may result from exposure to cyanide, its salts, or cyanogenic compounds, while residential fires are the most common condition of exposure. In fire victims, recognition of the cyanide toxidrome has been hampered by the short half-life in blood and poor stability of cyanide. In contrast, carboxyhemoglobin, as a marker of carbon monoxide poisoning, is easily measured and long-lasting. No evidence supports the assumption of the arbitrary fixed lethal thresholds of 50% for carboxyhemoglobin, and 3 mg/L for cyanide, in fire victims. Preliminary data, drawn when comparing pure carbon monoxide and pure cyanide poisonings, suggest that a cyanide toxidrome can be defined considering signs and symptoms induced by cyanide and carbon monoxide, respectively. Prospective studies in fire victims may provide value in clarifying signs and symptoms related to both toxicants. Cyanide can induce a lifethreatening poisoning from which a full recovery is possible. A number of experimentally efficient antidotes to cyanide exist, whose clinical use has been hampered due to serious side effects. The availability of potentially safer antidotes unveils the possibility of their value as first-line treatment, even in a complex clinical situation, where diagnosis is rapid and presumptive.

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.

Structural and cognitive deficits in chronic carbon monoxide intoxication: a voxel-based morphometry study

BACKGROUND

Patients with carbon monoxide (CO) intoxication may develop ongoing neurological and psychiatric symptoms that ebb and flow, a condition often called delayed encephalopathy (DE). The association between morphologic changes in the brain and neuropsychological deficits in DE is poorly understood.

METHODS

Magnetic resonance imaging and neuropsychological tests were conducted on 11 CO patients with DE, 11 patients without DE, and 15 age-, sex-, and education-matched healthy subjects. Differences in gray matter volume (GMV) between the subgroups were assessed and further correlated with diminished cognitive functioning.

RESULTS

As a group, the patients had lower regional GMV compared to controls in the following regions: basal ganglia, left claustrum, right amygdala, left hippocampus, parietal lobes, and left frontal lobe. The reduced GMV in the bilateral basal ganglia, left post-central gyrus, and left hippocampus correlated with decreased perceptual organization and processing speed function. Those CO patients characterized by DE patients had a lower GMV in the left anterior cingulate and right amygdala, as well as lower levels of cognitive function, than the non-DE patients.

CONCLUSIONS

Patients with CO intoxication in the chronic stage showed a worse cognitive and morphologic outcome, especially those with DE. This study provides additional evidence of gray matter structural abnormalities in the pathophysiology of DE in chronic CO intoxicated patients.

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.

Interrelation between the Poisoning Severity Score, carboxyhaemoglobin levels and in-hospital clinical course of carbon monoxide poisoning

The aim of the present study is to evaluate the relationship between the Poisoning Severity Score (PSS) and carboxyhaemoglobin (COHb) levels in patients with carbon monoxide poisoning (COP) using outcome as the measure. The study was designed as a retrospective chart review of patients with final diagnosis of COP. Correlation of PSS and COHb levels at presentation was evaluated with collected data. Majority of the cases were grade 1 (minor) PSS (134 cases, 73.6%) and 93.4% of these patients made a complete recovery. There were six deaths (mortality 3.3%) and six in-hospital major complications (IHMCs) (3.3%) (please specify whether the complications were in the patients who died). There is moderate correlation between PSS and outcome (p < 0.001, r = 0.493). Grade 3 (severe) PSS was significantly different from other grades for outcome (six mortalities and three IHMCs). Patients classified as grade 3 and patients who died had a significantly higher mean age (p < 0.05, 41.8 +/- 23.6 and p < 0.01, 60.1 +/- 20.3, respectively). Mean COHb level of grade 3 (33.2 +/- 13.9%) was significantly higher than that of other grades (p < 0.05). COHb levels according to outcome were not different (? within the patients in grade 3). Decreased level of consciousness, acidosis, tachycardia, high glucose and leucocyte levels showed significant relation with higher PSS, COHb level and adverse outcome. We conclude that the PSS is a reliable guide in COP. Value of the PSS in COP may be enhanced if additional factors and investigations are included.

The effects of amifostine and dexamethasone on brain tissue lipid peroxidation during oxygen treatment of carbon monoxide-poisoned rats

The mechanisms of injury of, and methods of treating patients with, carbon monoxide (CO) poisoning are poorly understood. Besides the hypoxic degenerative effects of CO, reoxygenation injury may play an important role. Amifostine (Ami), which is most often used in radiotherapy for its tissue protective characteristics, may offer benefits. In this study, investigators evaluated the effectiveness of various treatments in a CO-poisoned rat model. A total of 36 Wistar rats were randomly assigned to 1 of 6 groups (n=6 each), including control and poisoned groups exposed to CO at 2000 ppm (v/v) for 1 h, followed by various 1-h treatments: group C (control), group COair (ambient air), group CO-NBO (normobaric 100% oxygen), group CO-HBO (hyperbaric oxygen with 3 atmospheres absolute [3 ATA]), group CO-NBO-Ami (normobaric oxygen with intraperitoneal [i.p.] injection of amifostine 250 mg/kg body weight [bw]), and group CO-70O (70% O2 and 5% CO2 with dexamethasone 10 mg/kg bw, i.p.). Blood gas analysis, carboxyhemoglobin determination, brain tissue lipid peroxidation, and glutathione peroxidase (GSHPx), superoxide dismutase (SOD), lactate dehydrogenase (LDH), and creatine kinase (CK) activities were evaluated. Carboxyhemoglobin concentration in the air-treated group was 44+/-2%; it decreased to the control level with all oxygen treatments. Brain tissue GSH-Px and SOD measurements did not change. The activity of LDH in group CO-HBO and the activities of LDH and CK in group CO-70O were similar to those of group C. Lipid peroxides were high in ambient air and normobaric oxygen, but HBO, amifostine with oxygen, or 70% O2 reduced these to control levels (P<.05).

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.

Analysis of factors that influence rates of carbon monoxide uptake, distribution, and washout from blood and extravascular tissues using a multicompartment model

To better understand factors that influence carbon monoxide (CO) washout rates, we utilized a multicompartment mathematical model to predict rates of CO uptake, distribution in vascular and extravascular (muscle vs. other soft tissue) compartments, and washout over a range of exposure and washout conditions with varied subject-specific parameters. We fitted this model to experimental data from 15 human subjects, for whom subject-specific parameters were known, multiple washout carboxyhemoglobin (COHb) levels were available, and CO exposure conditions were identical, to investigate the contributions of exposure conditions and individual variability to CO washout from blood. We found that CO washout from venous blood was biphasic and that postexposure times at which COHb samples were obtained significantly influenced the calculated CO half times (P < 0.0001). The first, more rapid, phase of CO washout from the blood reflected the loss of CO to the expired air and to a slow uptake by the muscle compartment, whereas the second, slower washout phase was attributable to CO flow from the muscle compartment back to the blood and removal from blood via the expired air. When the model was used to predict the effects of varying exposure conditions for these subjects, the CO exposure duration, concentration, peak COHb levels, and subject-specific parameters each influenced washout half times. Blood volume divided by ventilation correlated better with half-time predictions than did cardiac output, muscle mass, or ventilation, but it explained only approximately 50% of half-time variability. Thus exposure conditions, COHb sampling times, and individual parameters should be considered when estimating CO washout rates for poisoning victims.

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.

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.

Carbon monoxide poisoning--a public health perspective

Carbon monoxide (CO) may be the cause of more than one-half of the fatal poisonings reported in many countries; fatal cases also are grossly under-reported or misdiagnosed by medical professionals. Therefore, the precise number of individuals who have suffered from CO intoxication is not known. The health effects associated with exposure to CO range from the more subtle cardiovascular and neurobehavioral effects at low concentrations to unconsciousness and death after acute or chronic exposure to higher concentrations of CO. The morbidity and mortality resulting from the latter exposures are described briefly to complete the picture of CO exposure in present-day society. The symptoms, signs, and prognosis of acute CO poisoning correlate poorly with the level of carboxyhemoglobin (COHb) measured at the time of hospital admission; however, because CO poisoning is a diagnosis frequently overlooked, the importance of measuring COHb in suspicious settings cannot be overstated. The early symptoms (headache, dizziness, weakness, nausea, confusion, disorientation, and visual disturbances) also have to be emphasized, especially if they recur with a regular periodicity or in the same environment. Complications occur frequently in CO poisoning. Immediate death is most likely cardiac in origin because myocardial tissues are most sensitive to the hypoxic effects of CO. Severe poisoning results in marked hypotension, lethal arrhythmias, and electrocardiographic changes. Pulmonary edema may occur. Neurological manifestation of acute CO poisoning includes disorientation, confusion, and coma. Perhaps the most insidious effect of CO poisoning is the development of delayed neuropsychiatric impairment within 2-28 days after poisoning and the slow resolution of neurobehavioral consequences. Carbon monoxide poisoning during pregnancy results in high risk for the mother by increasing the short-term complication rate and for the fetus by causing fetal death, developmental disorders, and chronic cerebral lesions. In conclusion, CO poisoning occurs frequently; has severe consequences, including immediate death; involves complications and late sequelae; and often is overlooked. Efforts in prevention and in public and medical education should be encouraged.

Carboxyhemoglobin half-life in carbon monoxide-poisoned patients treated with 100% oxygen at atmospheric pressure

STUDY OBJECTIVES

There are large reported differences for the carboxyhemoglobin (COHb) half-life (COHb t(1/2)) in humans breathing 100% atmospheric O(2) following CO inhalation in tightly controlled experiments compared to the COHb t(1/2) observed in clinical CO poisoning (range, 36 to 131 min, respectively). Other reports have suggested that the COHb t(1/2) may be affected by gender differences, age, and lung function. We wished to test the hypothesis that the COHb t(1/2) might also be influenced by CO poisoning vs experimental CO exposure, by a history of loss of consciousness (LOC), concurrent tobacco smoking, and by PaO(2). The purpose of the present study was to measure the COHb t(1/2) in a cohort of CO-poisoned patients and to determine if those listed factors influenced the COHb t(1/2).

DESIGN

Retrospective chart review from 1985 to 1995. We calculated the COHb t(1/2) of CO-poisoned patients who were treated with high-flow supplemental atmospheric pressure O(2) delivered by nonrebreather face mask or endotracheal tube.

SETTING

Hyperbaric medicine department of a tertiary-care teaching hospital.

PATIENTS

Of 240 CO-poisoned patients, 93 had at least two COHb measurements > 2% (upper limit of normal) with recorded times of the measurements, permitting calculation of the COHb t(1/2).

RESULTS

The COHb t(1/2) was 74 +/- 25 min (mean +/- 1 SD) with a range from 26 to 148 min. By stepwise multiple linear regression analysis, the PaO(2) influenced the COHb t(1/2) (R(2) = 0.19; p < 0.001), whereas the COHb t(1/2) was not influenced by gender, age, smoke inhalation, history of LOC, concurrent tobacco smoking, degree of initial metabolic acidosis (base excess), or initial COHb level.

CONCLUSIONS

The COHb t(1/2) of 93 CO-poisoned patients treated with 100% O(2) at atmospheric pressure was 74 +/- 25 min, considerably shorter than the COHb t(1/2) reported in prior clinical reports (approximately 130 +/- 130 min) and was influenced only by the patient's PaO(2).

Carbon monoxide poisoning

Carbon monoxide (CO) poisoning is common and frequently unrecognized since the signs and symptoms are relatively nonspecific. CO poisoning causes tissue hypoxia. Additionally, various animal studies have demonstrated that CO interferes with myoglobin, P450, and other enzyme function; causes lipid peroxidation through neutrophil activation; produces oxidative stress manifested by peroxynitrate deposition in endothelium; binds to cytochrome aa3, disrupting intracellular oxygen utilization; can cause neuroexcitotoxicity; and contributes to hippocampal cellular death through apoptosis. Emergency treatment for CO poisoning is 100% oxygen. Hyperbaric oxygen therapy (HBO2) is accepted in CO poisoning, although data from randomized clinical trials regarding the efficacy of HBO2 in CO poisoning is conflicting. CO poisoning, even when treated with supplemental oxygen can leave the patient with permanent neurocognitive or affective problems. Unfortunately, there appears to be no marker or constellation of signs or symptoms at presentation that predicts long-term outcome following CO poisoning. Given the neurocognitive sequelae following CO poisoning, increased awareness and prevention of CO poisoning is imperative.

British Hyperbaric Association carbon monoxide database, 1993-96

OBJECTIVES

To study the referral pattern of patients, poisoned with carbon monoxide and subsequently transferred to British hyperbaric oxygen facilities, from April 1993 until March 1996 inclusive.

METHODS

A standard dataset was used by hyperbaric facilities within the British Hyperbaric Association. The data on each patient were sent in confidence to the Hyperbaric Unit at Whipps Cross Hospital for analysis. The epidemiology of poisoning and the population studied were analysed. Times of removal from exposure, referral to a hyperbaric facility, arrival at the hyperbaric facility, and start of treatment were recorded. Data on the outcome of the episode were documented in one of the contributing facilities.

RESULTS

575 patients exposed to carbon monoxide were reported as being referred to British hyperbaric facilities in the three years, the busiest facilities being in London and Peterborough. The proportions of accidental and non-accidental exposures were 1:1.05. Of the accidental exposures, central heating faults were responsible in 71.5% of cases (n = 206). Smoke inhalation from fires was responsible for a further 13.5% (n = 39). The mean delay to arrival in a hyperbaric oxygen facility was 9 hours and 15 minutes after removal from exposure. Recovery after treatment was sometimes incomplete.

CONCLUSIONS

The reported pattern of referral was regionally weighted towards the south east of England. Smoke inhalation victims were often not referred for hyperbaric oxygen treatment. The delay to treatment was multifactorial; and the mean delay was well in excess of six hours. There is room for improvement in the consistency and speed of referral. Treatment schedules require standardisation. A central advice and referral service would be helpful.

Carbon monoxide poisoning: a review for clinicians

Carbon monoxide (CO) poisoning continues to be a significant health problem both in the United States and in many other countries. CO poisoning is associated with a high incidence of severe morbidity and mortality. Epidemics of CO poisoning commonly occur during winter months and sources include: smoke from fires, fumes from heating systems burning fuels, and exhaust fumes from motor vehicles. The history of exposure and carboxyhemoglobin levels should alert the physician to this diagnosis. In the absence of exposure history, CO poisoning should be considered when two or more patients are simultaneously sick. The clinical presentation is non-specific and may range from nausea and headache to profound central nervous system dysfunction. The mainstay of therapy for CO poisoning is supplemental oxygen, ventilatory support, and monitoring for cardiac dysrhythmias. This article reviews up-to-date information of this potentially devastating exposure.

A positron emission tomography study of patients with acute carbon monoxide poisoning treated by hyperbaric oxygen

Seven patients with an acute and severe carbon monoxide intoxication were treated with hyperbaric oxygen and underwent a positron emission tomographic examination 2-5 days after the acute event. Although the final clinical outcome was good in all patients, ischaemic changes were observed. Three patients with temporary sequelae after hyperbaric oxygen treatment showed the most severe changes, mainly in striatum and thalamus. Although positron emission tomographic examination cannot predict the final outcome, it can show the regions at risk for development of late complications following carbon monoxide poisoning.

Evoked potentials and cerebral blood flow in solvent induced psycho-organic syndrome

Epidemiological studies have provided evidence that neuropsychiatric symptoms are induced by long term exposure to solvents; individual diagnosis with psychometric tests, however, is not always possible (for example, when the patient has linguistic difficulties). Therefore evoked potentials and cerebral blood flow were studied in 50 patients occupationally exposed to solvents who were referred to our department and for whom a solvent induced psycho-organic syndrome was suspected. Degree of exposure was evaluated by its duration (mean 13.9, range 1 to 37 years) and its intensity (from an interview). At the group level, P22 and N35 latencies and amplitude N20-P22 of somatosensory evoked potentials were higher in cases than in controls (p < 0.05), whereas there was no difference for brainstem and visual evoked potentials, nor for hemispheric cerebral blood flow (but a higher distribution in the left occipital region was seen in patients, p < 0.05). Some parameters were linked to degree of exposure (amplitude N20-P22 of somatosensory evoked potentials, interpeak latency I-V of brainstem evoked potentials, distribution of cerebral blood flow in the internal frontal left region). At the individual level, these examinations were not of diagnostic value because sensitivity was low.

Pragmatic Problems in Prehospital Research

Emergency Medical Services (EMS) researchers face a variety of obstacles when conducting out-of-hospital investigations. This paper reviews some common problems and discusses practical solutions to facilitate the process and help avoid traps. This discussion focuses on prospective prehospital research.

One challenge to EMS research is to find new methods of improving the quality of care delivered in the field. There has been an emphasis placed on “exciting” topics, such as cardiac arrest and trauma resuscitation. Other events dominate the daily practice of prehospital medicine, but have not been well-studied. For example, what is the best way to immobilize the spine? What should be done for a patient with a suspected C-spine injury who is wearing a motorcycle helmet? No one has a scientifically proven approach to solve these common prehospital problems. There is a need to look at problems such as immobilization, asthma, overdose, and congestive heart failure to see what can be done differently in the field.

Hyperbaric oxygen therapy for acute smoke inhalation injuries

Hyperbaric oxygen therapy is an important adjunct in the management of respiratory injuries secondary to smoke inhalation, especially when injury is complicated by inhalation of a toxic chemical such as carbon monoxide or cyanide. For carbon monoxide poisoning, such therapy has become a standard of practice. As more information becomes available concerning the ability of hyperbaric oxygen to reduce reperfusion injuries, we anticipate that this therapy will become a standard of practice for managing smoke inhalation injuries and cyanide poisoning as well.

Methylene iodide poisoning

A 20-month-old girl ingested a maximum of 25 mL of pure methylene iodide. Within two hours, the patient exhibited lethargy and incoordination and vomited. An abdominal radiograph demonstrated the radiopaque material in the gut. In vivo conversion to carbon monoxide was documented with a peak carboxyhemoglobin level of 14.2% reached at 11 hours after ingestion. Two days after ingestion, evidence of hepatotoxicity was apparent, and fulminant hepatic failure quickly ensued. Despite aggressive supportive care and transfer to a liver transplant center, the patient died nine days after ingestion. Methylene iodide ingestion has not been previously reported in human beings. This case verifies that this substance is a potent hepatotoxin, is metabolized to carbon monoxide in vivo, is radiopaque, and may cause bone marrow suppression.