To use Map, simply import it from immutable JS and start to use it, as in the following code snippet:

import { Map } from 'immutable';

const person = {
  "resourceType": "Patient",
  "id": "example",
  "active": true,
  "gender": "male",
  "birthDate": "1974-12-25",
  "managingOrganization": {
    "reference": "Organization/1"
  }
};

// To create the equivalent in Immutable:
const immutablePerson = Map(person);