Use of a one-man, mobile pressure chamber in the treatment of carbon monoxide poisoning

Rapid elimination of CO through the lungs: coming full circle 100 years on

At the start of the 20th century, CO poisoning was treated by administering a combination of CO(2) and O(2) (carbogen) to stimulate ventilation. This treatment was reported to be highly effective, even reversing the deep coma of severe CO poisoning before patients arrived at the hospital. The efficacy of carbogen in treating CO poisoning was initially attributed to the absorption of CO(2); however, it was eventually realized that the increase in pulmonary ventilation was the predominant factor accelerating clearance of CO from the blood. The inhaled CO(2) in the carbogen stimulated ventilation but prevented hypocapnia and the resulting reductions in cerebral blood flow. By then, however, carbogen treatment for CO poisoning had been abandoned in favour of hyperbaric O(2). Now, a half-century later, there is accumulating evidence that hyperbaric O(2) is not efficacious, most probably because of delays in initiating treatment. We now also know that increases in pulmonary ventilation with O(2)-enriched gas can clear CO from the blood as fast, or very nearly as fast, as hyperbaric O(2). Compared with hyperbaric O(2), the technology for accelerating pulmonary clearance of CO with hyperoxic gas is not only portable and inexpensive, but also may be far more effective because treatment can be initiated sooner. In addition, the technology can be distributed more widely, especially in developing countries where the prevalence of CO poisoning is highest. Finally, early pulmonary CO clearance does not delay or preclude any other treatment, including subsequent treatment with hyperbaric O(2).

Immediate application of hyperbaric oxygen therapy using a newly devised transportable chamber

A transportable hyperbaric chamber called the Gamow bag has been reported as an effective means of treating high-altitude illness. The pressure limit of the original bag is set at 2 psi because of the fragility of the fabric. However, improvement of the hardware to make the bag capable of withstanding higher pressures has made it possible to perform standard hyperbaric oxygen therapy with the newly devised portable chamber, the Chamberlite 15. In this study, the safety of the new bag was examined using healthy human volunteers, and the bag was shown to be usable in clinical emergency cases, such as CO intoxication and decompression sickness. The effectiveness of emergency hyperbaric oxygen therapy was also examined using the CO intoxication model of the rat. It was suggested that hyperbaric therapy was especially beneficial if applied during the first 30 minutes of rescue work. It was concluded that the transportable chamber was a promising emergency tool for CO intoxication.

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 poisoning: a review epidemiology, pathophysiology, clinical findings, and treatment options including hyperbaric oxygen therapy

Carbon monoxide (CO) poisoning is the leading cause of poisoning deaths (accidental and intentional) in the United States. While confirmation of CO poisoning is easily obtained via assessment of carboxyhemoglobin (COHgb) levels, evaluation of the severity of intoxication is both difficult and inconsistent. Acute intoxication most commonly results in neurologic dysfunction and/or myocardial injury. Delayed neurologic sequelae are observed in approximately 10% of patients. New information from clinical observations and animal research has prompted a re-evaluation of the clinical assessment of the severity of CO intoxication and its resultant pathophysiology. Patients at the extremes of age (the very young and the elderly), those with pre-existing cardiovascular and/or pulmonary disease, as well as pregnancy are at increased risk. Once the diagnosis of CO poisoning has been established, treatment with 100% O2 is indicated. Based on the body of clinical, basic and scientific information currently available, patients who manifest signs of serious intoxication (i.e., unconsciousness or altered neurologic function, cardiac or hemodynamic instability) should be considered candidates for hyperbaric oxygen therapy (HBO) in addition to other appropriate supportive and intensive care. Any patient who has suffered an interval of unconsciousness, regardless of the patient's clinical exam on arrival, warrants HBO therapy. Treatment plans based on any specific COHgb level are not well founded.

Carbon monoxide poisoning

Carbon monoxide poisoning is a significant cause of illness and death. Its protean symptoms probably lead to a gross underestimation of its true incidence. Low levels of carbon monoxide aggravate chronic cardiopulmonary problems, and high levels are associated with cardiac arrhythmias and cerebral edema. Patients who survive acute poisoning are at risk of delayed neurologic sequelae. The measurement of carboxyhemoglobin levels does not reveal the tissue levels of carbon monoxide but is useful in determining therapy. Treatment includes the monitoring and management of cardiac arrhythmias and oxygenation. Hyperbaric oxygenation is beneficial, but there are currently no definite criteria for its use.

Acute carbon monoxide poisoning

Acute carbon monoxide poisoning most commonly follows inhalation of coal gas but may also occur from internal combustion engines fumes and in burns victims. The condition must be treated with urgency. This paper describes the pathology of formation and dissociation of carboxyhaemoglobin and discusses the management including normobaric and hyperbaric oxygen. It is recommended that hyperbaric oxygenation be used where possible in acute carbon monoxide poisoning.