This is from CMS:
Critical care is defined as a physician’s (or physicians’) direct delivery of medical care for a critically ill or critically injured patient. A critical illness or injury acutely impairs one or more vital organ systems such that there is a high probability of imminent or life threatening deterioration in the patient’s condition.
Critical care involves high complexity decision making to assess, manipulate, and support vital system functions to treat single, or multiple, vital organ system failure; and/or to prevent further life threatening deterioration of the patient’s condition.
Examples of vital organ system failure include (but are not limited to):
• Central nervous system failure;
• Circulatory failure;
• Shock;
• Renal, hepatic, metabolic, and/or respiratory failure.
Although it typically requires interpretation of multiple physiologic parameters and/or application of advanced technology(s), critical care may be provided in life threatening situations when these elements are not present.
You should remember that providing medical care to a critically ill, injured, or postoperative patient qualifies as a critical care service only if both the illness or injury and the treatment being provided meet the above requirements. While critical care is usually given in a critical care area such as a coronary care unit, intensive care unit, respiratory care unit, or the emergency department, payment may also be made for critical care services that you provide in any location as long as this care meets the critical care definition.
Critical care services must be reasonable and medically necessary. As explained above, critical care services encompass both the treatment of “vital organ failure” and “prevention of further life threatening deterioration in the patient’s condition.”
Therefore, delivering critical care in a moment of crisis, or upon being called to the patient’s bedside emergently, is not the only requirement for providing critical care service. Treatment and management of a patient’s condition, in the threat of imminent deterioration; while not necessarily emergent, is required.