Also, as many patient transport ambulances carry a second stretcher, non-emergency ambulance officers can be utilised to assist emergency crews in incidents involving numerous casualties. In Victoria, PTOs & AAs will respond to Medium Acuity 000 calls that are dispatched through the ESTA Referral Service. This is the basic level of pre-hospital emergency care. These paramedics hold a Certificate IV Health Care (Ambulance) (previously known as Certificate IV in Emergency Care), or equivalent, and are trained in basic life support skills. Paramedics practice includes all components of the basic life support level and the further enhancement of IV cannulation, drug therapy (oral, intramuscular injection (IM), intravenously (IV), narcotic pain relief, anti-emetics, cardiac arrest, respiratory drugs, etc.), fluid resuscitation, advanced airway management (usually a laryngeal mask airway [LMA], or endotracheal intubation and Cricothyroidotomy in Western Australia) and the maintenance of infusions. Paramedics perform extensive physical assessment, blood examinations (e.g. random glucose test), interpret electrocardiograms (ECG), SpO2, temperature, and provide care for a range of patients from the new born to the elderly. ICP or MICA paramedics are able to practice intensive care procedures such as endotracheal intubation, surgical airways, rapid sequence intubation (RSI), nasotracheal intubation, chest tube insertion, and drug infusions (e.g. Adrenaline, Salbutamol, sedation, thrombolytics etc.). IC or MICA paramedics practice under clinical practice guidelines independently of medical control. The Council of Ambulance Authorities is currently lobbying for an expanded scope of practice to permit more primary care by advance care paramedics, including the role of paramedic as independent practitioner. Some ambulance services employ paramedics specially trained in rescue or special operations techniques. Officers can be trained in areas such as road crash rescue, vertical rescue, confined space and trench rescue. They learn navigation skills, four wheel driving, urban search and rescue, and chemical biological and radiological procedures. Retrieval or flight paramedics work on fixed wing and helicopter aircraft in many states, performing both emergency and routine transport operations. They are generally considered to be extremely highly trained in emergency medical care, but also aviation medicine, rescue and aviation emergencies. In some states this role is performed by a Flight Nurse or Flight Doctor with specialist qualifications in Intensive Care or Emergency Medicine who is then supported by a Flight Paramedic who is usually credentialed at IC or MICA level.