physician assistants are other types of non-physician providers that care for patients in icus. these providers have fewer years of in-school training, typically receive further clinical on the job education, and work as part of the team under the supervision of physicians. pharmacists critical care pharmacists work with the medical team in many aspects, but some include, monitoring serum concentrations of medication, past medication use, current medication use, and medication allergies. their typically round with the team, but it may differ by institution. some pharmacist after attaining their doctorate or pharmacy may pursue additional training in a postgraduate residency and become certified as critical care pharmacists. pharmacists help manage all aspects of drug therapy and may pursue additional credentialing in critical care medicine as bcccp by the board of pharmaceutical specialties. many critical care pharmacists are a part of the multi-professional society of critical care medicine. inclusion of pharmacist decreases drug reactions and poor outcomes for patients. registered dietitians nutrition in intensive care units presents unique challenges due to changes in patient metabolism and physiology while critically ill. critical care nutrition is rapidly becoming a subspecialty for dieticians who can pursue additional training and achieve certification in enteral and parenteral nutrition through the american society for parenteral and enteral nutrition (aspen). respiratory therapists respiratory therapists often work in intensive care units to monitor how well a patient is breathing. respiratory therapists may pursue additional education and training leading to credentialing in adult critical care (accs) and neonatal and pediatric (nps) specialties. respiratory therapists have been trained to monitor a patient's breathing, provide treatments to help their breathing, evaluate for respiratory improvement, and manage mechanical ventilation parameters. they may be involved in emergency care like inserting and managing an airway, humidification of oxygen, administering diagnostic lung mechanics tests, invasive or non-invasive mechanical ventilation management, weaning the ventilator, aerosol therapy (pulmonary vasodilatory medications included), inhaled nitric oxide therapy, arterial blood gas analysis, and providing physiotherapy. additionally, respiratory therapists are commonly involved in ecmo management and many pursue certification in such therapies due to the intimate relationship of the heart and lungs. on-going critical care management of an ecmo patient commonly requires strict ventilator management in relation to the type of ecmo support used. ethical and medicolegal issues economics in general, it is the most expensive, technologically advanced and resource-intensive area of medical care. in the united states, estimates of the 2000 expenditure for critical care medicine ranged from us$19–55 billion. during that year, critical care medicine accounted for 0.56% of gdp, 4.2% of national health expenditure and about 13% of hospital costs. in 2011, hospital stays with icu services accounted for just over one-quarter of all discharges (29.9%) but nearly one-half of aggregate total hospital charges (47.5%) in the united states. the mean hospital charge was 2.5 times higher for discharges with icu services than for those without.