of some additional medications. Paramedic Paramedics typically represent the highest degree of pre-hospital medical provider, providing advanced life support (ALS) care. Paramedics perform a variety of medical procedures such as endotracheal intubation, rapid sequence induction, cricothyrotomy, fluid resuscitation, drug administration, obtaining intravenous and intraosseous access, manual defibrillation, electrocardiogram interpretation, capnography, cardioversion, transcutaneous pacing, pericardiocentesis, thoracostomy, ultrasonography, and blood chemistry interpretation. Staffing levels An ambulance with only EMTs is considered a basic life support (BLS) unit, an ambulance utilizing AEMTs is dubbed an "intermediate life support" (ILS), or "limited advanced life support" (LALS) unit, and an ambulance with paramedics is dubbed an "advanced life support" (ALS) unit. Many states allow ambulance crews to contain a mix of crews levels (e.g. an EMT and a paramedic or an AEMT and a paramedic) to staff ambulances and operate at the level of the highest trained provider. There is nothing stopping supplemental crew members to be of a certain certification, though (e.g. if an ALS ambulance is required to have two paramedics, then it is acceptable to have two paramedics and an EMT). An emergency vehicle with only EMRs or a combination of both EMRs and EMTs is still dubbed a "basic life support" (BLS) unit. An EMR must usually be overseen by an EMT-level provider or higher to work on a transporting ambulance. Education and training EMT training programs for certification vary greatly from course to course, provided that each course at least meets local and national requirements. In the United States, EMRs receive at least 40–80 hours of classroom training and EMTs receive at least 120–300 hours of classroom training. AEMTs generally have 100-300 hours of additional classroom training beyond the standard EMT training. Paramedics are trained for 1,500–2,500 hours or more. In addition to each level's didactic education, clinical rotations are typically also required. Similar in a sense to medical school clinical rotations, EMT students are required to spend a required amount of time in an ambulance and on a variety of hospital services (e.g. obstetrics, emergency medicine, surgery, intensive care unit, psychiatry) in order to complete a course and become eligible for the certification and licensure exams. The number of clinical hours for both time in an ambulance and time in the hospital vary depending on local requirements, the level the student is obtaining, and the amount of time it takes the student to show competency. In addition, a minimum