However, imaging techniques that may support the diagnosis (each with limited sensitivity and thus should not be used to exclude the diagnosis) include the following: Echocardiography (showing air in the cardiac chambers) Chest CT (showing local lung injury or hemorrhage) Head CT (showing intravascular gas and diffuse edema), although visible arterial gas is inconsistently present and its absence does not rule out arterial gas embolism Abdominal CT (showing gas within mesenteric vessels or the portal vein) Assessment should also include evaluation for other potential causes of loss of consciousness, including carbon monoxide poisoning due to contaminated breathing gas.