Hemodynamic collapse is a common indication for admission of critically ill patients to a monitored ICU setting. The trained intensivist, familiar with the vast differential diagnosis of circulatory shock, must respond rapidly to resuscitate and correct the underlying process responsible for the life-threatening perturbation in organ perfusion.

Shock may be defined as a state in which profound and widespread reduction of effective delivery of oxygen and other nutrients to the tissues leads first to reversible and then, if prolonged, to irreversible cellular injury. In patients with cancer, sepsis and septic shock are common as a result of their underlying immunosuppression, cytotoxic therapy, and need for chronic vascular access. Pericardial tamponade and dysrhythmias are seen commonly with metastatic pericardial disease. Pulmonary embolism is frequent in patients with cancer because of their hypercoagulable state, and patients with malignancies can be severely oligemic from postchemotherapy emesis, diarrhea, decreased oral intake, or hemorrhage from the tumor. Thrombocytopenia as a result of underlying disease or therapy can predispose these patients to hemorrhagic complications further. Although cardiogenic shock as a consequence of cancer therapy is uncommon, myocardial systolic function can be affected profoundly by some chemotherapeutic agents; this disrupted function can lead to congestive heart failure. Coronary artery disease and cancer frequently coexist in elderly persons. Ischemic events related to cancer surgery, chemotherapy, radiation arteritis, or acute illness also can necessitate admission to the intensive care unit.

Because numerous textbooks, monographs, and review articles deal with the broad topic of circulatory collapse, this article concentrates exclusively on clinical conditions seen in patients with cancer, resulting directly from their malignancy or as a complication of therapy. This article is not intended to be all-inclusive, and discussions of conditions such as venous thromboembolic disease and anaphylaxis are found elsewhere in this volume.