When should calcium chloride be administered in relation to blood transfusion?

Calcium chloride should be administered after the first unit of blood is transfused primarily due to its effects on calcium levels in the body. When multiple units of blood are transfused, especially products that are citrate-anticoagulated, there is a risk of hypocalcemia. This is because citrate can bind calcium, leading to decreased ionized calcium levels in the blood.

By waiting until after the first unit of blood has been administered, medical personnel can assess the patient's response to the transfusion and monitor vital signs, thus ensuring that calcium chloride is given based on the actual need rather than as a routine preemptive measure. This practice helps to prevent unnecessary interventions and allows for a more focused treatment approach, addressing any hypocalcemia that may arise as transfusions continue.

In military and tactical environments where blood products are administered in potentially unstable patients, this practice helps to ensure that care is adaptive and based on real-time assessment of the patient's condition.