 Blood transfusions these days are generally very safe, but they can still cause serious harm with a condition called transfusion-related acute lung injury, or trolley. Trolley is a leading cause of death related to the use of blood products. A new review in the journal Anesthesiology provides an overview of the condition and makes the case for why anesthesiologists should be on the front lines fighting it. Classically, trolley is defined as a lung injury occurring within six hours of a blood transfusion. Onset can also be delayed 24 to 72 hours in critically ill patients in the ICU or OR. Trolley is not fully understood but is frequently described as a two-hit process. Baseline inflammation within the recipient establishes increased risk in part due to neutrophils in the lungs. A full-blown injury occurs only after a transfusion when antibodies or lipids, extracellular vesicles, or signaling molecules activate neutrophils and damage the lining of blood vessels and lung tissues, causing pulmonary edema and respiratory distress. Identifying the condition can be challenging because none of the signs of trolley, which often include rapid onset of pulmonary edema, hypoxemia, and tachypnea, are specific. Nevertheless, there are risk factors including pre-existing patient factors associated with inflammation such as smoking or liver disease, transfusion-related factors like receiving large volumes of transfused blood or aged platelets, and perioperative factors such as cardiopulmonary bypass or other high-risk surgeries with frail patients. The authors propose that perioperative trolley operates under a three-hit model. As in the classic two-hit model, patient factors comprise the first hit, predisposing patients to developing trolley once they receive a transfusion, which is the second hit. Surgery, or hit three, then combines additively or synergistically with the two other hits, making perioperative trolley that much more likely. This is why anesthesiologists are especially well-situated to be on the lookout for trolley. They supervise numerous transfusions and trolley is more likely in perioperative patients. In that regard, anesthesiologists should screen for high-risk patients before surgery by considering factors related to all three hits. They should also encourage use of patients' lead management strategies to reduce or prevent transfusions during surgery and facilitate communication among the care team. There are no specific treatments for trolley, but as soon as it's suspected, supportive care, such as oxygen, can be given. Any ongoing transfusions should be stopped, and the blood bank should be notified so they can assist in preventing additional injury to the patient. Find out more, including tips on how to differentiate trolley and the latest on emerging biomarkers for the condition by reading the full review.