Get Full Reimbursements For Critical Care Medical Billing Codes When performing medical billing for critical care services, much accuracy must be followed. It may not be the most important thing on a physician’s mind when a critical patient comes into the emergency room, but medical billing elements cannot be overlooked. There are two elements that are imperative for critical care medical billing: time and medical necessity. In order to use the codes 99291 or 99292 (Critical care, evaluation and management of the critically ill or critically injured patient; first 30-74 minutes and each additional 30 minutes), the patient must have a critical illness or injury. Critical is defined as having …