Final answer:
A patient vomiting during a blood transfusion could be experiencing a severe hemolytic transfusion reaction due to receiving incompatible blood, requiring urgent medical attention. In emergencies where blood type is unknown, O negative blood is used as it's universally compatible. Immediate medical intervention is crucial.
Step-by-step explanation:
If a patient receiving a blood transfusion begins to vomit, it may be indicative of a transfusion reaction, potentially a hemolytic transfusion reaction (HTR). This type of reaction can occur when the blood type transfused is not compatible with the recipient's blood type. For example, if a person with type B blood is given type A blood, their anti-A antibodies will attack the transfused RBCs. This incompatible transfusion can lead to symptoms such as fever, chills, itching, hives, difficulty breathing, and low blood pressure within 1 to 24 hours. Vomiting along with these symptoms warrants immediate medical attention as severe cases can lead to shock or even death.
In an emergency where a patient's blood type cannot be confirmed, such as after a motor vehicle accident with severe bleeding, O negative blood is typically transfused because it is the universal donor type and is less likely to cause an HTR. However, even with O negative blood, cross-matching should be performed as soon as possible to ensure total compatibility.