In cases of suspected CO poisoning, which assessment method would best evaluate the degree of exposure?

• A. COHb by arterial blood analysis
• B. Multiple wavelength spectrophotometry
• C. PaO2 by arterial blood gas
• D. O2 saturation by pulse oximetry

Answer: (B)

The most effective method for evaluating the degree of exposure to carbon monoxide (CO) is the measurement of carboxyhemoglobin (COHb) levels in arterial blood through specific analysis. This method provides an accurate representation of the amount of carbon monoxide bound to hemoglobin in the bloodstream and is crucial in cases of suspected CO poisoning.

While multiple wavelength spectrophotometry is a technique used in various clinical settings, it does not directly provide the COHb levels as effectively as arterial blood analysis does. This specific analysis is essential, as carboxyhemoglobin levels correlate strongly with the severity of CO toxicity and guide treatment decisions.

Other methods, such as measuring PaO2 or O2 saturation, do not accurately reflect the presence of CO in the bloodstream. Pulse oximetry, for instance, cannot differentiate between oxyhemoglobin and carboxyhemoglobin, potentially leading to misleading results in cases of CO exposure. Therefore, COHb by arterial blood analysis is the most reliable way to assess the extent of carbon monoxide exposure and determine appropriate medical intervention.