Outcome of patients experiencing cardiac arrest with carbon monoxide poisoning treated with hyperbaric oxygen

Unexpected carboxyhemoglobin half-life during cardiopulmonary resuscitation: a case report

BACKGROUND

Cardiac arrest (CA) following CO poisoning (CO-induced CA) exposes patients to an extremely high risk of mortality and remains challenging to treat effectively. Terminal carboxyhemoglobin elimination half-life (COHbt_1/2) is critically affected by ventilation, oxygen therapy, and cardiac output, which are severely affected conditions in cases of CA.

CASE PRESENTATION

Asystole occurred in an 18-year-old woman after unintentional exposure to CO in her bathroom. Cardiopulmonary resuscitation (CPR) was started immediately, including mechanical ventilation with a fraction of inspired oxygen (FiO₂) of 1.0 and external chest compressions with a LUCAS® device. CPR was stopped after 101 min, as it was unsuccessful. During this period, we calculated a COHbt_1/2 of 40.3 min using a single compartmental model.

CONCLUSIONS

This result suggests that prolongation of CPR time needed to back COHb at 10%, a level more compatible with successful return of spontaneous circulation (ROSC), could be compatible with a realistic CPR time. Calculating COHbt_1/2 during CPR may help with decision-making regarding the optimal duration of resuscitation efforts and further with HBO₂ or ECLS. Further evidence-based data are needed to confirm this result.

Clinical Outcomes and Mortality Impact of Hyperbaric Oxygen Therapy in Patients With Carbon Monoxide Poisoning

OBJECTIVES

Carbon monoxide poisoning affects 50,000 per year in the United States alone. Mortality is approximately 3%, and up to 40% of survivors suffer from permanent neurocognitive and affective deficits. Hyperbaric oxygen therapy has shown benefit on reducing the long-term neurologic sequelae of carbon monoxide poisoning but has not demonstrated improved survival. The objective of this study is to assess the efficacy of hyperbaric oxygen for acute and long-term mortality in carbon monoxide poisoning using a large clinical databank.

DESIGN

Retrospective analysis.

SETTING

University of Pittsburgh Medical Center healthcare system (Pittsburgh, PA).

PATIENTS

One-thousand ninety-nine unique encounters of adult patients with carbon monoxide poisoning.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Baseline demographics, laboratory values, hospital charge transactions, discharge disposition, and clinical information from charting were obtained from the electronic medical record. In propensity-adjusted analysis, hyperbaric oxygen therapy was associated with a reduction in inpatient mortality (absolute risk reduction, 2.1% [3.7-0.9%]; p = 0.001) and a reduction in 1-year mortality (absolute risk reduction, 2.1% [3.8-0.4%]; p = 0.013).

CONCLUSIONS

These data demonstrate that hyperbaric oxygen is associated with reduced acute and reduced 1-year mortality. Further studies are needed on the mortality effects of hyperbaric oxygen therapy in carbon monoxide poisoning.

Long-Distance Transportation of Carbon Monoxide-Poisoned Patients on Extracorporeal Membrane Oxygenation Seems Possible: A Porcine Feasibility Study

OBJECTIVE

Extracorporeal membrane oxygenation (ECMO) has been widely used to stabilize patients with impairment of cardiac/respiratory function, and ECMO has been used to stabilize cardiopulmonary insufficiency caused by carbon monoxide (CO) poisoning in a porcine model. Airborne transportation in fixed wing aircraft of patients suffering from CO poisoning is challenging because as the air pressure drops, the oxygen content falls correspondingly. The aim of this study was to show the feasibility of cannulating and establishing ECMO therapy during airborne transportation after severe CO poisoning in a porcine model.

METHODS

An anesthetized pig was subjected to severe CO poisoning and loaded onto a Hercules aircraft. Cardiac arrest was induced at an altitude of 8,000 feet, after which cannulation and the establishment of venoarterial (VA) ECMO were performed. Vital signs were monitored, and arterial blood samples were analyzed while airborne.

RESULTS

CO poisoning was induced with carboxyhemoglobin at 58% before takeoff. We successfully cannulated the animal in-flight during cardiac arrest and initiated VA ECMO. The animal regained spontaneous circulation and was successfully weaned from ECMO. During VA ECMO, PaO₂ was maintained at high levels (420-615 mm Hg).

CONCLUSION

It is possible to cannulate and initiate VA ECMO treatment as airborne en route therapy for cardiac arrest and severe CO intoxication in a porcine model.

ECMO improves survival following cardiogenic shock due to carbon monoxide poisoning - an experimental porcine model

Background

Severe intoxication with carbon monoxide (CO) is extremely lethal and causes numerous deaths due to cardiac or respiratory failure. Conventional intensive treatment may not be sufficient. The aim of this study was to investigate the treatment effect of extracorporeal veno-arterial extracorporeal membrane oxygenation (ECMO) following severe CO poisoning in an experimental porcine model.

Methods

A total of twelve pigs were anaesthetized, routinely monitored and intoxicated by inhalation of CO until the beginning of cardiac failure and randomized to a treatment (ventilator using an FiO₂ of 100% or ECMO). In the case of cardiac arrest, advanced resuscitation using standard guidelines was performed for at least 10 min. ECMO was also initiated in the ventilation group if the return of spontaneous circulation did not occur within 10 min. Lung tissue biopsies were obtained before and after CO intoxication.

Results

All animals in the ECMO group survived; however, one had to be resuscitated due to cardiac arrest. A single animal survived in the ventilator group, but five animals suffered from cardiac arrest at an average of 11.8 min after initiation of treatment. Conventional resuscitation failed in these animals, but four animals were successfully resuscitated after the establishment of ECMO.

A significant decrease was noticed in PO₂ with increasing HbCO, but there was no increase in pulmonary vascular resistance. No differences in H&E-stained lung tissue biopsies were observed.

Conclusions

The use of ECMO following severe CO poisoning greatly improved survival compared with conventional resuscitation in an experimental porcine model. This study forms the basis for further research among patients.

A novel effective chemical hemin for the treatment of acute carbon monoxide poisoning in mice

There is no effective drug for the therapy of acute carbon monoxide (CO) poisoning. The purpose of the present study was to investigate the potential preventive and therapeutic effects of hemin on an animal model of acute CO poisoning and to provide a potential therapeutic candidate drug. A total of 80 Kunming mice were randomly divided into four groups, namely the air control, acute CO poisoning, hemin-treatment + CO and hemin-pretreatment + CO groups (n=20 each). Furthermore, the mortality rate of mice, blood carboxyhaemoglobin (HbCO) concentration and serum malondialdehyde (MDA) concentration were measured, and pathological changes of the hippocampal area were determined using histochemical staining. The mice with acute CO poisoning had a 50% mortality rate at 1 h, with an increase in blood HbCO, serum MDA levels and pathological impairments of the hippocampus. Furthermore, the mortality rate, blood HbCO and serum MDA levels of mice with pretreatment and treatment of hemin were decreased. Additionally, the pathological changes of the hippocampal area were improved in the hemin-treatment and hemin-pretreatment groups compared with the mice treated with CO. These results suggest that hemin is a novel effective chemical for the prevention and treatment of acute CO poisoning in mice. Therefore, the present study provides a novel method and experimental basis for the application of hemin in treating patients with acute CO poisoning.

Abnormal fingernail beds following carbon monoxide poisoning: a case report and review of the literature

Introduction

Carbon monoxide poisoning is a very common cause of death in accidental, suicidal, or homicidal cases throughout the world. Fingernail bed manifestation is reported in survivors of carbon monoxide poisoning.

Case presentation

A 40-year-old Caucasian woman was exposed to carbon monoxide when she was sleeping alone in her one-bedroom apartment; fortunately, the beeps from her First Alert combination smoke and carbon monoxide detector woke her and she was saved from any extensive health issues. The most indicative symptoms experienced were a severe headache, blurred vision, agitation, and confusion. Following contact with the Emergency Responses Services, she was promptly transferred to the hospital via ambulance and was treated with high-flow oxygen on the way. She was discharged from the emergency department on the same day, but carbon monoxide exposure had already had adverse effects on her fingernail beds. The fingernail tips were altered and appeared as if a bite had been taken out of their distal borders. The changes in the tips of her fingernails were significant, but they completely disappeared eight weeks later without any additional treatment.

Conclusions

Worldwide, carbon monoxide poisoning is a potentially lethal condition that is preventable with educational programs and installation of carbon monoxide detectors in the home setting. Exposure to carbon monoxide frequently goes unrecognized until it is too late and causes silent death. To the best of the authors’ knowledge, this is the first report in the literature of fingernail bed manifestations in a survivor of carbon monoxide poisoning.

Monitoring the treatment of myocardial stunning syndrome after acute carbon monoxide poisoning using arterial pulse wave analysis: a case report

Myocardial injury due to acute carbon monoxide intoxication is often refractory to standard resuscitation methods. Levosimendan is a new inotropic agent that is used in the treatment of acute and chronic heart failure. We report a case of severe cardiopulmonary compromise after exposure to carbon monoxide in a 40-year-old woman who was monitored using transthoracic echocardiography and the arterial pulse contour analysis system (FloTrac) and successfully treated with levosimendan.

Practice recommendations in the diagnosis, management, and prevention of carbon monoxide poisoning

Carbon monoxide (CO) poisoning is common in modern society, resulting in significant morbidity and mortality in the United States annually. Over the past two decades, sufficient information has been published about carbon monoxide poisoning in the medical literature to draw firm conclusions about many aspects of the pathophysiology, diagnosis, and clinical management of the syndrome, along with evidence-based recommendations for optimal clinical practice. This article provides clinical practice guidance to the pulmonary and critical care community regarding the diagnosis, management, and prevention of acute CO poisoning. The article represents the consensus opinion of four recognized content experts in the field. Supporting data were drawn from the published, peer-reviewed literature on CO poisoning, placing emphasis on selecting studies that most closely mirror clinical practice.

S-100beta and neuron-specific enolase levels in carbon monoxide-related brain injury

INTRODUCTION

Carbon monoxide (CO) toxicity may cause persistent injuries in tissues sensitive to hypoxia. Neuropsychiatric sequelae may be observed in about 67% of cases after severe CO exposure.

AIM

The aims of this study were to demonstrate the usefulness of S-100beta and neuron-specific enolase (NSE) in CO intoxications, show the degree of neurological response, and determine the indications for hyperbaric oxygen treatment (HBOT) as biochemical markers.

RESULTS

The S-100beta and NSE levels of the sera of 30 patients were studied upon admittance and at the third and sixth hours. S-100beta levels were found to be high in all 3 analyses. There was no significant change in NSE levels. When the S-100beta levels were compared with Glasgow Coma Scale levels, a strong negative correlation was found for all hours (r = -0.7, -0.8; P = .00). The correlation between S-100beta and carboxyhemoglobin levels at the initial hour was found to be statistically significant (r = 0.4; P = .01). The S-100beta levels in patients receiving HBOT showed a considerable decrease compared with those in patients not receiving the treatment. The same decrease was valid for NSE, although it was insignificant.

CONCLUSION

S-100beta may be useful in evaluating intoxications as an early biochemical marker in CO intoxications, as well as in the differential diagnosis due to other causes, and in determining HBOT indications.

Risk factors for short-term mortality from carbon monoxide poisoning treated with hyperbaric oxygen

OBJECTIVE

Carbon monoxide (CO) poisoning is common in the United States, accounting for approximately 2,700 deaths annually. Few publications have described the mortality rate of CO-poisoned patients who survive to reach a hospital and die despite maximal medical care. Further, while risk factors for cognitive sequelae in survivors of CO poisoning have become clearer recently, factors associated with death are less well defined. This study was conducted to 1) determine the short-term mortality risk for patients treated with hyperbaric oxygen for CO poisoning, and 2) determine whether any factors related to the poisoning episode are predictive of mortality.

DESIGN/SETTING/PATIENTS

A departmental database and medical records of 1,505 consecutive patients treated with hyperbaric oxygen at a single institution from 1978 to 2005 were reviewed.

MEASUREMENTS

Demographic and clinical data were extracted for analysis. Mortality data, including cause of death, were obtained through a search of the National Death Index of the National Center for Health Statistics.

MAIN RESULTS

A total of 38 patients experienced short-term mortality from their episode of CO poisoning, yielding a death rate of 2.6% in medically treated patients. Characteristics significantly associated with mortality included fire as a source of CO, loss of consciousness, carboxyhemoglobin level, arterial pH, and presence of endotracheal intubation during hyperbaric treatment.

CONCLUSIONS

The mortality rate for medically treated CO-poisoned patients in this series was 2.6%, similar to the limited combined experience previously reported in the literature. Factors most strongly associated with mortality were severe metabolic acidosis and need for endotracheal intubation.

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.

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.

Hyperoxia in lethal methemoglobinemia: effects on oxygen transport, tissue oxygenation, and survival in pigs

BACKGROUND

Treatment of severe methemoglobinemia includes the avoidance of methemoglobin-inducing drugs, the application of methylene blue, and the administration of supplementary oxygen. However, the efficacy of the latter on oxygen transport, tissue oxygenation, and survival in the treatment of extreme methemoglobinemia is ambiguous. The objective was to assess whether using hyperoxic ventilation as the sole therapeutic intervention (i.e., ventilation with pure oxygen, Fio2 1.0) improves the short-term (6-hr) survival rate during otherwise lethal methemoglobinemia.

DESIGN

Prospective, randomized, controlled study.

SETTING

Experimental animal laboratory of a university hospital.

SUBJECTS

Fourteen anesthetized, mechanically ventilated pigs.

INTERVENTIONS

After induction of profound methemoglobinemia (60 +/- 2%) by the injection of 15 mg/kg 4-dimethylaminophenol, artificial ventilation either was continued with room air (G 0.21, n = 7) or was changed over to hyperoxic ventilation (G 1.0, n = 7). A constant level of methemoglobinemia was maintained by continuous infusion of 4-dimethylaminophenol throughout a 6-hr follow-up period.

MEASUREMENTS AND MAIN RESULTS

All animals died within the 6-hr follow-up period, but survival time was prolonged in animals ventilated with pure oxygen (G 0.21, 105 +/- 30 mins; G 1.0, 210 +/- 64 mins, p < .05). No differences were encountered between G 0.21 and G 1.0 with respect to the investigated variables of macrohemodynamics, oxygen transport, and tissue oxygenation.

CONCLUSIONS

Hyperoxic ventilation has negligible effects on oxygen transport and tissue oxygenation during lethal methemoglobinemia; nevertheless, survival was increased without severe adverse reactions provoked by hyperoxic ventilation.

Effect of hyperbaric oxygenation on intracranial pressure elevation rate in rats during the early phase of severe traumatic brain injury

Intracranial pressure (ICP) was monitored to evaluate the therapeutic effect of hyperbaric oxygen (HBO(2)) treatment following traumatic brain injury (TBI). This subject is controversial. The aim of our study was to determine whether HBO(2) treatment has a therapeutic effect on ICP dynamics and survival following severe fluid percussion brain injury (FPBI) in rats. Changes in ICP level were analyzed every 30 min during an 8-h monitoring period following trauma and at the end of experiment (20 h). The control (A) and experimental (B) groups consisted of 7 and 4 rats, respectively. Group B was subjected to 1.5 atmospheres absolute (ATA) 100% oxygen for 60 min beginning 2 h after FPBI. No significant differences in ICP were noted between groups A and B before and after HBO(2) treatment until 3.5 h after trauma. At 4 h, for the first time, the difference became significant (P = 0.025; n = 11) and remained significant (P < 0.05) for all measurement points until end of monitoring, when mean ICP values reached 37.17 +/- 14.25 and 20.25 +/- 2.63 mm Hg in groups A and B, respectively. Linear approximation models showed different trends (b1 = 3.80 +/- 0.23; r(2) = 0.65, P < 0.001 and b1 = 1.56 +/- 0.25; r(2) = 0.77, P < 0.001) for groups A and B, respectively. Covariance analysis confirmed significant differences between slopes for groups A and B (F = 148.04, P < 0.001; df = 2,177), i.e., a significant difference in mean rate of ICP elevation. By the end of the experiment, 3 out of 7 rats from group A had died, but none from group B. We conclude that the application of HBO(2) during the early phase of severe FPBI significantly diminished ICP elevation rate and decreased mortality level.

Cardiovascular manifestations of moderate to severe carbon monoxide poisoning

OBJECTIVES

We describe the cardiovascular manifestations of carbon monoxide (CO) poisoning.

BACKGROUND

Carbon monoxide poisoning is a common cause of toxicologic morbidity and mortality. Although the neurologic sequelae of CO poisoning have been well described, the cardiovascular consequences are limited to isolated case reports.

METHODS

We reviewed the cardiovascular manifestations of 230 consecutive patients treated for moderate to severe CO poisoning in the hyperbaric oxygen chamber at Hennepin County Medical Center (HCMC), a regional center for treatment of CO poisoning.

RESULTS

The mean age was 47.2 years with 72% men. Ischemic electrocardiogram (ECG) changes were present in 30% of patients, whereas only 16% had a normal ECG. Cardiac biomarkers (creatine kinase-MB fraction or troponin I) were elevated in 35% of patients. In-hospital mortality was 5%.

CONCLUSIONS

Cardiovascular sequelae of CO poisoning are frequent, with myocardial injury assessed by biomarkers or ECG in 37% of patients. Patients admitted to the hospital with CO poisoning should have a baseline ECG and serial cardiac biomarkers.

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.

S100B protein in carbon monoxide poisoning: a pilot study

Carbon monoxide (CO) poisoning is the most common form of lethal poisoning. The aim of this prospective clinical study was to assess the possible role of S100B, the structural protein in the astroglia, as a biochemical marker of brain injury in carbon monoxide poisoning. Serum S100B determination was performed in 38 consecutive patients poisoned by carbon monoxide who were admitted to the Emergency Department (ED) in Ljubljana. All three unconscious patients had elevated S100B levels. The patient with the highest S100B died. S100B was elevated in two of the six patients with initial transitory unconsciousness at the scene. All 29 patients without loss of consciousness had normal S100B levels. Carbon monoxide poisoning appears to be associated with elevated S100B levels.

Community-acquired pneumonia: process of care studies

New insight has been gained into the relationship between the processes of care undertaken for patients with community-acquired pneumonia and the resulting outcomes. Better insight into the risks for a complicated course can increase the percentage of patients treated as outpatients. Studies have also suggested that both the promptness and the choice of antibiotic therapy can affect patient outcomes. Promptly switching to oral antibiotic therapy can often lead to a shorter length of hospital stay; however, concern has arisen regarding the effect of shorter lengths of stay on patient outcomes.