A multicenter, prospective study of fetal outcome following accidental carbon monoxide poisoning in pregnancy

Carbon Monoxide Poisoning: From Occupational Health to Emergency Medicine

Carbon monoxide poisoning remains a leading cause of accidental poisoning worldwide (both at home and at work), and it is also a cause of suicidal poisoning. Such poisoning can arise following prolonged exposure to low levels of CO or following brief exposure to high concentrations of the gas. In fact, despite exposure limits, high safety standards, and the availability of CO alarms, nearly 50,000 people in the United States visit the emergency department each year due to poisoning. Additionally, CO poisoning in the United States causes up to 500 deaths each year. Despite the widespread nature of this form of poisoning, known about for centuries and whose damage mechanisms have been recognized (or rather hypothesized about) since the 1800s, early recognition, especially of late complications, and treatment remain a medical challenge. A well-designed therapeutic diagnostic process is necessary so that indication for hyperbaric or normobaric therapy is correctly made and so that patients are followed up even after acute exposure to diagnose late complications early. Furthermore, it is necessary to consider that in the setting of emergency medicine, CO poisoning can be part of a differential diagnosis along with other more frequent conditions, making its recognition difficult. The last thirty years have been marked by a significant increase in knowledge regarding the toxicity of CO, as well as its functioning and its importance at physiological concentrations in mammalian systems. This review, taking into account the significant progress made in recent years, aims to reconsider the pathogenicity of CO, which is not trivially just poisonous to tissues. A revision of the paradigm, especially as regards treatment and sequelae, appears necessary, and new studies should focus on this new point of view.

Open issues in management of carbon monoxide poisoning in pregnancy: practical suggestions

Carbon monoxide (CO) poisoning during pregnancy may cause deleterious effects to the fetus. Hyperbaric oxygen therapy (HBO) in pregnancy is proven to be safe and it is considered to be beneficial, reducing the severity of the fetal injuries. However, a number of issues are still to be discussed, among them the question of the carboxyhemoglobin (COHb) levels that trigger HBO therapy in pregnant CO poisoned patients. In this letter we report some practical suggestions for organizations wishing to develop their own protocols.

Perinatal Carbon Monoxide Poisoning: Treatment of a 2-Hour-Old Neonate with Hyperbaric Oxygen

A 41-year-old gravida 4 para 3 (G4P3) and 38 ^5/7 weeks pregnant woman presented to labor and delivery with dizziness, headache, and decreased fetal movement after 12 hours of exposure to carbon monoxide (CO) from a grill that was used inside for heat. The mother was hemodynamically stable, and her neurologic examination was intact. Her carboxyhemoglobin level, which was obtained 12 hours after removal from the CO exposure, was 7.4%. The fetus's heart rate was 173 beats per minute with moderate variability and one late appearing deceleration, not associated with contractions. The biophysical profile score was 2 of 8. The obstetrics team performed a routine cesarean section. The 1- and 5-minute Apgar's scores were 7 and 8, respectively. The arterial cord gas result was as follows: pH = 7.05, PCO ₂  = 71 mm Hg, pO ₂  = 19 mm Hg, bicarbonate = 14 mmol/L, and carboxyhemoglobin = 11.9%. The mother and infant were treated with hyperbaric oxygen therapy consisting of 100% oxygen at 2.4 atmosphere absolutes (ATA) for 90 minutes at 2.5 hours after delivery. Following one hyperbaric oxygen treatment, the infant was transitioned to room air and routine postpartum treatment and was discharged 3 days later in good condition. Hyperbaric oxygen treatment was well tolerated in this neonate.

Hypoxia: A teratogen underlying a range of congenital disruptions, dysplasias, and malformations

In this review, we explore evidence that hypoxia in the developing human fetus can lead not only to the more commonly accepted disruptive-type defects, but also patterns of anomalies that suggest that hypoxia can exert a more classic teratogenic effect, using the brain as one example. We review neuropathology in the context of intrauterine hypoxia, particularly as it relates to carbon monoxide poisoning, in utero strokes, and homozygous alpha-thalassemia. In general, the associated brain injuries resemble those seen with other causes of hypoxic-ischemic injury. Fetal strokes during development usually lead to loss of brain tissue in areas that do not follow a typical embryologic pattern, and therefore are considered disruptions. However, there is also evidence that fetal brain ischemia can cause more classically recognized patterns of abnormal embryonic neuronal migration and organization such as polymicrogyria, cortical dysplasia, or dysgenesis, including select types of focal cortical dysplasia. This study summarizes available literature and evidence to raise clinicians' awareness regarding the association between hypoxia and congenital anomalies, including brain malformations.

Carbon monoxide poisoning during pregnancy treated with hyperbaric oxygen

Acute carbon monoxide (CO) intoxication during pregnancy causes fetal death and teratogenic effects. Hyperbaric oxygen (HBO2) therapy has the potential to improve them. HBO2 therapy should be considered to treat CO intoxication during pregnancy.

Hyperbaric oxygen therapy in carbon monoxide poisoning in pregnancy: Maternal and fetal outcome

OBJECTIVE

Closer monitoring and treatment is vital for pregnant carbon monoxide (CO) poisoning cases due to fetal poisoning component. Permanent damage can occur in both the mother and the baby. It may cause stillbirth even though no serious clinical symptoms occur in the mother. Hyperbaric oxygen (HBO) treatment is advised for all pregnant patients regardless of their clinical symptoms. Pregnant CO poisoning patients that received HBO treatment and their fetal status were evaluated in this study.

METHODS

Pregnant patients poisoned with CO treated in the same hyperbaric clinic were evaluated. Pregnant patients that received HBO treatment in a multiplace chamber were evaluated in terms of clinical status, demographic structure, laboratory tests, fetal effects and progress of the fetus until birth and 6 months postpartum.

RESULTS

A total number of 32 pregnant cases were treated. COHb values were over 20% (min 6.9- max 40.2) in 23 patients, 11 patients had a history of syncope. All patients took HBO treatment under 2.4 ATA pressure for 120 min. 3 patients received more than 1 session of HBO treatments due to fetal stress; all other cases took 1 session of HBO treatment. No spontaneous abortus occurred in early follow-ups; only 4 babies were born prematurely. 2 of the babies were lost in the early phases after birth, due to causes non-related to CO poisoning complications (cyanotic heart disease, necrotising enterocolitis). No significant difference were observed in the comparison of laboratory results of patients with syncope and of those who did not have syncope and comparison of patients with COHb value higher than 20% and patients with COHb value lower than 20% (p > 0.05).

CONCLUSION

HBO is not advisable for pregnant patients except for CO poisoning. In this study it is observed that HBO treatment under 2.4 ATA pressure for 120 min has no harmful effects on the mother and the fetus. It is observed that continuation of HBO treatment in the cases with fetal distress findings has beneficial effects. COHb levels and syncope were shown to have no significant effect on clinical symptoms and on blood tests.

Effectiveness of Hyperbaric Oxygenation Versus Normobaric Oxygenation Therapy in Carbon Monoxide Poisoning: A Systematic Review

Carbon monoxide (CO) is a gas product of combustion, considered highly poisonous. Prolonged CO exposure is responsible for more than half of fatal poisonings and is also one of the leading causes of poisoning in Western countries. We aimed to compare the effectiveness of therapy with hyperbaric oxygen (HBO) versus normobaric oxygen (NBO) in the setting of carbon monoxide poisoning (COP). We independently searched the National Library of Medicine's Medline (PubMed™), ScienceDirect™, and Scielo™ for any relevant studies published from 1989 to 2017, using the following keywords: hyperbaric therapy, hyperbaric oxygenation, normobaric therapy, carbon monoxide poisoning, carboxyhemoglobin, Haldane effect. We analyzed the studies that suggested the effectiveness of HBO or NBO. Also, we searched for studies related to COP; including history, epidemiology (risk factors, incidence, demographics), pathophysiology, clinical manifestations, diagnosis, and treatment. Sixty-eight articles were found, sixteen of which dealt with either HBO or NBO or both. Twelve suggested HBO as the treatment of choice in COP; four studies indicated that NBO was an adequate treatment due to its cost-effectiveness and availability in the emergency department (ED). HBO has been shown in several studies to be effective in moderate to high-risk COP situations, being the therapy of choice to avoid sequelae, especially neurologically. NBO can be considered as a reasonable alternative due to its cost-effectiveness. The availability and understanding of different therapeutic interventions are critical in the management of patients with COP in ED and the Critical Care unit.

Acute effects of air pollution on spontaneous abortion, premature delivery, and stillbirth in Ahvaz, Iran: a time-series study

Living in areas with high air pollution may have adverse effects on human health. There are few studies about the association between breathing polluted air and adverse pregnancy outcomes in the Middle East. The aim of this study was to determine the relationship between air pollution and spontaneous abortion, premature birth, and stillbirth in Ahvaz. A time-series study was conducted. Data about spontaneous abortion, premature deliveries, and stillbirth was collected from Ahvaz Imam Khomeini Hospital. Air pollution data including NO, CO, NO₂, PM₁₀, SO₂, O₃, and climate data were, respectively, collected from the Environmental Protection Agency and the Khuzestan Province Meteorology Office from March 2008 until March 2015. The relationship between air pollutants with the number of abortions, premature births, and stillbirths was found using a quasi-Poisson distributed lag model, adjusted by trend, seasonality, temperature, relative humidity, weekdays, and holidays. The average daily dust in Ahvaz on 7.2% days of the year was higher than 500 μg/m³ (very dangerous). Findings from this study indicate a significant association between each 10-unit increase in SO₂ and spontaneous abortion in lag 0 and 9 days. There was a significant relation between each 10-unit increase in NO₂ and CO, and premature birth in lag 0. Also, we found a significant association between each 10-unit increase in CO and premature delivery in lag 1; PM₁₀ and premature delivery in lags 10, 11, and 12; and NO and premature delivery in lags 3, 4, 10, 11, 12, and 13 (p value < 0.05). Contact with polluted air during pregnancy may increase adverse pregnancy outcomes and stillbirth. Pregnant women should avoid polluted air.

Assessing Exposure to Household Air Pollution: A Systematic Review and Pooled Analysis of Carbon Monoxide as a Surrogate Measure of Particulate Matter

BACKGROUND

Household air pollution from solid fuel burning is a leading contributor to disease burden globally. Fine particulate matter (PM_2.5) is thought to be responsible for many of these health impacts. A co-pollutant, carbon monoxide (CO) has been widely used as a surrogate measure of PM_2.5 in studies of household air pollution.

OBJECTIVE

The goal was to evaluate the validity of exposure to CO as a surrogate of exposure to PM_2.5 in studies of household air pollution and the consistency of the PM_2.5-CO relationship across different study settings and conditions.

METHODS

We conducted a systematic review of studies with exposure and/or cooking area PM_2.5 and CO measurements and assembled 2,048 PM_2.5 and CO measurements from a subset of studies (18 cooking area studies and 9 personal exposure studies) retained in the systematic review. We conducted pooled multivariate analyses of PM_2.5-CO associations, evaluating fuels, urbanicity, season, study, and CO methods as covariates and effect modifiers.

RESULTS

We retained 61 of 70 studies for review, representing 27 countries. Reported PM_2.5-CO correlations (r) were lower for personal exposure (range: 0.22-0.97; median=0.57) than for cooking areas (range: 0.10-0.96; median=0.71). In the pooled analyses of personal exposure and cooking area concentrations, the variation in ln(CO) explained 13% and 48% of the variation in ln(PM_2.5), respectively.

CONCLUSIONS

Our results suggest that exposure to CO is not a consistently valid surrogate measure of exposure to PM_2.5. Studies measuring CO exposure as a surrogate measure of PM exposure should conduct local validation studies for different stove/fuel types and seasons. https://doi.org/10.1289/EHP767.

Carbon Monoxide Exposure During Pregnancy

IMPORTANCE

Carbon monoxide (CO) is the leading cause of poisoning in the United States and is associated with high maternal and fetal mortality rates. Given the nonspecific signs and symptoms of toxicity, cases may go unsuspected or attributed to other etiologies. As CO adversely affects both mother and fetus, it is important for practitioners to recognize and treat poisoning in a timely manner.

OBJECTIVE

We seek to assist practitioners with understanding the physiology and recognizing the presentations of both acute and chronic CO poisoning, as well as provide information on diagnosis and treatment options. We also conducted a review of cases described in the literature during the past half century to show varying presentations and treatment methodologies.

EVIDENCE ACQUISITION

A qualitative literature search was conducted using PubMed and Google Scholar for articles published between 1970 and 2014 that assessed cases of CO poisoning during pregnancy. Excluded studies were not in English or contained nonhuman subjects.

RESULTS

Nineteen published reports of CO poisoning during pregnancy described in varying levels of detail were found in the literature from 1971 to 2010.

CONCLUSIONS AND RELEVANCE

Carbon monoxide poisoning requires a high degree of suspicion. Diagnosis is made based on initial history and physical evaluation and assessment of environmental CO levels; presenting carboxyhemoglobin levels may be poor indicators of severity of disease. Oxygen therapy should be initiated promptly in all possible cases with consideration of hyperbaric oxygen therapy in cases of significant maternal exposure. Treatment requires a longer duration for fetal CO elimination than in the nonpregnant patients. Importantly, practitioners should educate pregnant patients on prevention.

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.

[Urgent cesarean section in a pregnant woman with carbon monoxide poisoning]

Recognition of carbon monoxide is difficult due to its plain physical-chemical properties. Carbon and gas operating heating systems may cause severe poisoning. Carbon-monoxide intoxication may generate severe hypoxic damage and it may cause death. The authors present the case of severe carbon monoxide poisoning affecting one young child and five adults, including a pregnant woman. Because the availability of hyperbaric oxygen therapy is limited in Hungary, urgent cesarean section was performed to avoid intrauterine hypoxic damage. The authors note that there are no standardized non-invasive methods for measuring fetal carbon-monoxide level and that the level of carbon monoxide accumulation is higher and the clearance is longer in the fetus than in the mother. The pathophysiology of carbon monoxide intoxication and therapeutic options in pregnancy are discussed.

[Ten practical issues concerning acute poisoning with carbon monoxide in pregnant women]

BACKGROUND

The poisoning of carbon monoxide (CO) is the leading cause of death by poisoning in France. Its consequences are potentially serious to the fetus. Literature is ancient and little known.

PURPOSE AND METHOD

Make an inventory of knowledge about carbon monoxide poisoning during pregnancy.

RESULT

The CO causes maternal then fetal tissue hypoxia primarily by binding to hemoglobin with which it has a high affinity. Its transplacental passage may cause fetal harm, predominantly in the brain. Severity seems correlated with maternal symptoms during exposure. In the absence of maternal symptoms, however, the available data are reassuring. Hyperbaric oxygen therapy may reduce the risk to the fetus.

DISCUSSION

Oxygen therapy should be offered in all cases of CO poisoning, especially if there are maternal symptoms during exposure. In addition, a fetal echography directed on the cephalic pole - even a fetal magnetic resonance imaging three weeks after exposure - should also be proposed.

Carbon monoxide poisoning

Carbon monoxide (CO) poisoning is the leading cause of death as a result of unintentional poisoning in the United States. CO toxicity is the result of a combination of tissue hypoxia-ischemia secondary to carboxyhemoglobin formation and direct CO-mediated damage at a cellular level. Presenting symptoms are mostly nonspecific and depend on the duration of exposure and levels of CO. Diagnosis is made by prompt measurement of carboxyhemoglobin levels. Treatment consists of the patient's removal from the source of exposure and the immediate administration of 100% supplemental oxygen in addition to aggressive supportive measures. The use of hyperbaric oxygen is controversial.

Ambient air pollution and congenital heart disease: a register-based study

Maternal exposure to ambient air pollution has increasingly been linked to adverse pregnancy outcomes. The evidence linking this exposure to congenital anomalies is still limited and controversial. This case-control study investigated the association between maternal exposure to ambient particulate matter with aerodynamic diameter less than 10 μm (PM(10)), sulfur dioxide (SO(2)), nitrogen dioxide, nitric oxide (NO), ozone (O(3)), and carbon monoxide (CO) and the occurrence of congenital heart disease in the population of Northeast England (1993-2003). Each case and control was assigned weekly average (weeks 3-8 of pregnancy) of pollutant levels measured by the closest monitor to the mother's residential postcode. Using exposure as both continuous and categorical variables, logistic regression models were constructed to quantify the adjusted odds ratios of exposure to air pollutants and the occurrence of each outcome group. We found exposure to CO and NO to be associated with ventricular septal defect and cardiac septa malformations. CO was also associated with congenital pulmonary valve stenosis and NO with pooled cases of congenital heart disease and tetralogy of Fallot. Findings for SO(2), O(3) and PM(10) were less consistent.

Clinical policy: critical issues in the management of adult patients presenting to the emergency department with acute carbon monoxide poisoning

This clinical policy focuses on critical issues concerning the management of adult patients presenting to the emergency department (ED) with acute symptomatic carbon monoxide (CO) poisoning. The subcommittee reviewed the medical literature relevant to the questions posed. The critical questions are: Should hyperbaric oxygen (HBO(2)) therapy be used for the treatment of patients with acute CO poisoning; and Can clinical or laboratory criteria identify CO-poisoned patients who are most or least likely to benefit from this therapy? Recommendations are provided on the basis of the strength of evidence of the literature. Level A recommendations represent patient management principles that reflect a high degree of clinical certainty; Level B recommendations represent patient management principles that reflect moderate clinical certainty; and Level C recommendations represent other patient management strategies that are based on preliminary, inconclusive, or conflicting evidence, or based on committee consensus. This clinical policy is intended for physicians working in hospital-based EDs.

Cerebral palsy due to nonlethal maternal carbon monoxide intoxication

BACKGROUND

Carbon monoxide (CO) poisoning in pregnancy is a relatively rare occurrence, but it can result in fetal mortality and neurologic complications in fetuses who survive to term.

CASE

We describe the course of an infant who was acutely exposed to CO at 20 weeks of gestation.

CONCLUSIONS

We conclude that despite maternal well-being, CO intoxication at critical periods of human brain development can lead to hypoxic-ischemic lesions in the globus pallidus and that dystonic cerebral palsy may develop in the infant during long-term follow-up.

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.

Carbon monoxide poisoning in a parturient and the use of hyperbaric oxygen for treatment

We report a case of carbon monoxide (CO) intoxication in a pregnant woman who presented with acute non-specific symptoms and fetal distress. She was scheduled for urgent caesarean section but this was averted after consultation, advice and discussion from a National Poisons Centre, obstetricians and physicians managing the local hyperbaric oxygen facility. Hyperbaric oxygen (HBO) was used successfully to treat both the woman and her fetus. This resulted in a normal reactive fetal cardiotochograph (CTG) trace after treatment and the fetus was delivered 6 weeks later by normal vaginal delivery. The effects of CO intoxication and the use of HBO on the pregnant woman and her fetus are discussed.

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.

Poisons in the air: a cause of chronic disease in children

Children represent the largest subpopulation of those susceptible to the adverse effects of air pollution. Compared to adults, children express a greater vulnerability, which can be explained by differences in: the circumstances of exposure related to age, their activities, their child status, differences in lung anatomy and physiology, differences in the clinical expression of disease, and their organ maturity. Many factors have to be assessed in order to evaluate the severity of toxic exposures: pollutant solubility, particle size, concentration, reactivity of pollutants, and pattern of ventilation. Within the numerous air pollutants, some are of special concern for children. For example, ozone has been shown to affect the lungs of healthy school children, especially asthmatics. Airborne particles, nitrogen oxides, sulfur oxides, and acid aerosols have also been shown to induce acute respiratory symptoms, asthma, and bronchitis. Of particular importance is carbon monoxide, which, under certain circumstances, may be found in highly toxic concentrations indoors where children spend most of their time. Special attention has to be given to children's unique differences in order to evaluate the clinical consequences of their toxic exposures. This circumstance emphasizes the key roles of poison centers, clinical toxicologists, and pediatricians, all of whom can collaborate on the identification, assessment, and surveillance of toxic risk for child health and development.

Is air pollution a risk factor for low birth weight in Seoul?

Environmental factors contributing to reduced birth weight are of great concern because of the well-known relation of birth weight to infant mortality and adverse effects in later life. We examined the associations between air pollution exposures during pregnancy and low birth weight among all full-term births (gestational age 37-44 weeks) for a 2-year period (January 1996 through December 1997) in Seoul, South Korea. We evaluated these associations with a generalized additive logistic regression adjusting for gestational age, maternal age, parental educational level, parity, and infant sex. We used smoothing plots with generalized additive models to analyze the exposure-response relation for each air pollutant. The adjusted relative risk of low birth weight was 1.08 [95% confidence interval (CI) = 1.04-1.12] for each interquartile increase for carbon monoxide concentrations during the first trimester of pregnancy. The relative risks were 1.07 (95% CI = 1.03-1.11) for nitrogen dioxide, 1.06 (95% CI = 1.02-1.10) for sulfur dioxide, and 1.04 (95% CI = 1.00-1.08) for total suspended particles also for interquartile increase in exposure. Carbon monoxide, nitrogen dioxide, sulfur dioxide, and total suspended particle concentrations in the first trimester of pregnancy period are risk factors for low birth weight.

Indoor air pollutants in homes and schools

Exposure to the four indoor air pollutants mentioned in this article may cause illnesses and fatalities in children. It is important for pediatricians to be aware of each of them and to remove children from environments contaminated with these pollutants. Guidance about monitoring the indoor air and interpreting the results is difficult to find. A chart of proposed guidelines may help the pediatrician faced with an indoor air problem (Table 1).

Risks and benefits of nicotine to aid smoking cessation in pregnancy

Cigarette smoking during pregnancy is the single largest modifiable risk for pregnancy-related morbidity and mortality in the US. Addiction to nicotine prevents many pregnant women who wish to quit smoking from doing so. The safety and efficacy of nicotine replacement therapy (NRT) for smoking cessation during pregnancy have not been well studied. Nicotine is classified by the US Food and Drug Administration as a Pregnancy Category D drug. Animal studies indicate that nicotine adversely affects the developing fetal CNS, and nicotine effects on the brain may be involved in the pathophysiology of sudden infant death syndrome (SIDS). It has been assumed that the cardiovascular effects of nicotine resulting in reduced blood flow to the placenta (uteroplacental insufficiency) is the predominant mechanism of the reproductive toxicity of cigarette smoking during pregnancy. Short term high doses of nicotine in pregnant animals do adversely affect the maternal and fetal cardiovascular systems. However, studies of the acute effects of NRT in pregnant humans indicate that nicotine alone has minimal effects upon the maternal and fetal cardiovascular systems. Cigarette smoking delivers thousands of chemicals, some of which are well documented reproductive toxins (e.g. carbon monoxide and lead). A myriad of cellular and molecular biological abnormalities have been documented in placentas, fetuses, and newborns of pregnant women who smoke. The cumulative abnormalities produced by the various toxins in cigarette smoke are probably responsible for the numerous adverse reproductive outcomes associated with smoking. It is doubtful that the reproductive toxicity of cigarette smoking is primarily related to nicotine. We recommend the following. Efficacy trials of NRT as adjunctive therapy for smoking cessation during pregnancy should be conducted. The initial dose of nicotine in NRT should be similar to the dose of nicotine that the pregnant woman received from smoking. Intermittent-use formulations of NRT (gum, spray, inhaler) are preferred because the total dose of nicotine delivered to the fetus will be less than with continuous-use formulations (transdermal patch). A national registry for NRT use during pregnancy should be created to prospectively collect obstetrical outcome data from NRT efficacy trials and from individual use. The goal of this registry would be to determine the safety of NRT use during pregnancy, especially with respect to uncommon outcomes such as placental abruption. Finally, our review of the data indicate that minimal amounts of nicotine are excreted into breast milk and that NRT can be safely used by breast-feeding mothers.

Hyperbaric oxygen therapy in childhood carbon monoxide poisoning

Hyperbaric oxygen therapy is the administration of 100% oxygen at pressures two to three times ambient pressure, and it significantly increases dissolved oxygen content. Although it has been used successfully to treat decompression illness and arterial air embolism, its role in the treatment of carbon monoxide poisoning remains somewhat controversial. Published evidence and guidelines for the use of hyperbaric oxygen therapy in carbon monoxide-poisoned infants and children are scarce compared with those available for carbon monoxide-poisoned adults. Because of their higher metabolic rates and developing nervous systems, infants and children may be more susceptible to the effects of carbon monoxide and also may warrant special considerations. This review focuses on the unique aspects of carbon monoxide poisoning and hyperbaric oxygen therapy in the fetus, the newborn, the infant, and the child. In addition, it discusses general indications for and special and practical considerations in the use of hyperbaric oxygen therapy in children.

Hair analysis--a biological marker for passive smoking in pregnancy and childhood

Passive smoking has been shown to adversely affect the health of infants and children. We used hair analysis for nicotine and its metabolite cotinine as a biological marker for exposure to smoking in these two groups. Using radioimmunoassay we measured maternal and fetal hair concentrations of nicotine and cotinine in the mother-infant pairs belonging to three different groups based on the mother's smoking habits. The three groups were: active smokers, passive smokers and nonsmokers. There was a significant correlation between maternal and neonatal hair concentration for both, nicotine and cotinine. Mothers and infants in the smoking groups, both active and passive, had significantly higher hair concentrations of both, nicotine and cotinine than in the control, nonsmoking group. In an older cohort, we compared two groups: 78 asthmatic children were compared to 86 healthy children exposed to similar degrees of passive smoking. By using objective, biological markers, our study aimed at verifying whether asthmatic children are different from nonasthmatic children in the way their bodies handle nicotine. Our results show, that, despite the fact that parents of asthmatic children tend to smoke a lower number of cigarettes per day, their children had an average twofold higher concentrations of cotinine in their hair then the control, nonasthmatic children. These studies document the importance of hair analysis as a tool for measuring exposure to cigarette smoke.

The Organization of Teratology Information Services (OTIS) Registry Study

Some population-based studies of the risks of gestational medication use are limited by differential recall or enrollment of mothers of children with abnormalities. Prospective acquisition of exposure information, before knowledge of pregnancy outcome, is the most unbiased manner in which to obtain denominator-based outcome information. The Organization of Teratology Information Services (OTIS) Registry Study will prospectively evaluate pregnancy outcomes in relation to exposures to asthma medications. Patients will be enrolled by participating Teratology Information Services. Information regarding medication exposure, asthma severity, and other important medical events will be assessed during pregnancy by means of standardized interviews, supplemented by medical records. Outcome information will be obtained from copies of the pediatric records. Data analysis will evaluate relative risks of adverse outcomes in exposed compared with unexposed asthmatic and nonasthmatic subjects.

Carbon monoxide poisoning. Early awareness and intervention can save lives

Each year, particularly during the heating season, thousands of people are poisoned by carbon monoxide, with potentially devastating outcomes. Initial diagnosis can be difficult because symptoms closely resemble those of influenza and are often misinterpreted. Dr Tomaszewski discusses diagnosis and treatment, including the benefits and risks of hyperbaric oxygen therapy.

Poisoning and drug overdose

Poisoning is a common cause for intensive care unit admission for both children and adults, and most poisoning victims are effectively treated using standard decontamination measures and supportive care. For a small number of poisons, acceleration of toxin removal with hemodialysis or hemofiltration is indicated. Similarly, specific antidotes are indicated in a few selected circumstances. Rarely, patients may benefit from more aggressive supportive techniques such as cardiopulmonary bypass.

Occupational reproductive hazards

Although the causes of many reproductive disorders remain unknown, scientific evidence is accumulating to implicate occupational agents in fertility disorders and adverse pregnancy outcomes. Effective assessment and management of workers exposed to reproductive hazards often involves a team-based approach. By identifying potential reproductive hazards, making appropriate referrals, and by educating and advocating for patients, clinicians can play an important part in safeguarding the reproductive health of workers.

Accidental electric shock in pregnancy: a prospective cohort study

OBJECTIVE

Our purpose was to quantify fetal risk after accidental electric shock in pregnancy.

STUDY DESIGN

All pregnant women who were counseled by the Motherisk Program in Toronto and by the Vermont Pregnancy Risk Information Service in Burlington after having an electric shock during pregnancy were enrolled in a prospective, controlled, observational study.

RESULTS

Thirty-one women were followed up after delivery: 26 had been exposed to 110 V, 2 to 220 V, 2 to high voltage, and 1 to 12 V. Twenty-eight women gave birth to healthy normal infants, one had a child with a ventricular septal defect, and two had spontaneous abortions. In the control group there were 30 healthy babies; one woman had a spontaneous abortion. There were no differences between the groups in pregnancy outcome, birth weight, gestational age, type of delivery, or rates of neonatal distress.

CONCLUSION

In most cases accidental electric shock occurring during day-to-day life during pregnancy does not pose a major fetal risk.

Carbon monoxide poisoning: easy to treat but difficult to recognise

Carbon monoxide (CO) poisoning is a common medical emergency and a frequent cause of deliberate or accidental death. It can cause acute and chronic central nervous system damage which may be minimised by prompt treatment with 100% oxygen or hyperbaric oxygen therapy. However, recognition of this intoxication can be difficult. Failure to diagnose it may have disastrous effects on the patient, and other members of the household who could subsequently become intoxicated. Guidance on the correct diagnosis of this condition is provided in the light of a number of studies screening emergency room populations. Guidelines for treatment with hyperbaric oxygen therapy are also reviewed.

Fetal methemoglobinemia: a cause of nonimmune hydrops fetalis

A case of nonimmune hydrops fetalis resulting from fetal methemoglobinemia is presented. A woman with a pregnancy at 17 weeks' gestation was admitted after combustion gas intoxication. Although the mother totally recovered, the fetus showed signs of nonimmune hydrops fetalis at follow-up. Fetal methemoglobin levels were very high.

Warehouse workers' headache: emergency evaluation and management of 30 patients with carbon monoxide poisoning

BACKGROUND

Carbon monoxide (CO) is the leading cause of fatal toxic inhalation in the United States, but the medical literature contains few reports of mass exposures. Warehouse workers' headache (WWH) is an infrequently reported form of CO poisoning due to industrial exposure.

METHODS

We describe 30 persons who developed WWH after inhaling exhaust from a propane-fueled forklift, their emergency medical management at a small community hospital, and their long-term courses.

RESULTS

Workers with more direct exposures to vented exhaust had significantly higher expired CO levels (21.1 +/- 0.7% versus 8.4 +/- 4.8%, P < 0.0001) and higher acute symptom scores (9.0 +/- 2.2 versus 4.7 +/- 3.3, P = 0.01) than persons with less direct exposures. Work location, expired CO levels, and acute symptom scores did not correlate with symptom scores 2 years after exposure. Workers experiencing acute difficulty concentrating or confusion had higher expired CO levels than persons with neither of these symptoms (16.3 +/- 6.7% versus 8.4 +/- 5.2%, P = 0.005) and developed higher chronic symptom scores (3.9 +/- 3.0 versus 1.1 +/- 1.5, P = 0.04), suggesting that this subgroup may require closer follow-up for long-term complications.

CONCLUSION

With earlier recognition of ongoing CO toxicity, this disaster would likely have been averted. Since CO exposures are more common than is often recognized, general internists must be familiar with the manifestations of CO toxicity, its timely evaluation, management, and prevention.

Carbon monoxide intoxication during pregnancy: a case presentation and pathophysiologic discussion, with emphasis on molecular mechanisms

In carbon monoxide (CO) poisoning, the mortality and morbidity risk does not always correlate with the level of carboxyhemoglobin (COHb). Recent studies confirm that the mitochondrial cytochrome portion of the respiratory chain is susceptible to CO toxicity at concentrations traditionally considered nontoxic. These laboratory findings correlate with subtle neurologic symptoms detected by psychometric studies in individuals many days from the time of acute intoxication. Additionally, in the pregnant patient, a time lag for both uptake and elimination of CO between the mother and fetus has been demonstrated, with the fetus at risk for hypoxia even when the mother's blood level of CO is nontoxic. Hyperbaric oxygen (HBO) therapy in pregnant patients has not been shown to have adverse effects on the fetus. We present a case of CO intoxication in late pregnancy treated with HBO therapy without adverse consequences.