High-dose methotrexate chemotherapy is indicated in osteosarcoma and some types of lymphoma. The drug is very toxic for the kidneys and must be administered with hydratation and intravenous bicarbonate to keep the urine alkaline. Leucovorin is also given every six hours. One failure in one step of this “linear” process is transmited down with a short period of time to correct the situation.
The Diagnostic process itself can be linear or complex. Another classification based on the time that a team or a professional needs to correct a failure is derivated from the “Natural Accident Theory” from Charles Perrow who defined two types of relationship between coupled processes: tightly coupled and loosely coupled.
Examples of a complex and loosely coupled process is the typical diagnosis activity in Internal Medicine where different specialties and diagnostic techniques are involved and there is time to rethink the situation. On the other hand, an example of a linear and tightly process is the attention to a myocardial infarction at the ED or the administration of high-dose of methotrexate, where time to correct a failure is a key aspect.