Thomas and Pollio argue in their book Listening to patients: a phenomenological approach to nursing theory and practice (2002) that the interpretive phenomenology of Heidegger and Gadamer concerns itself with universal essences and requires adaptation and modification in order to make it effective for nursing research and practice, which both look at concrete experiences and situations of patients. They mention that in K Caelli’s The changing face of phenomenological research: traditional and American phenomenology in nursing (Qualitative health research, 10(3), 2000, 366-377), at least 20 different kinds of phenomenology have arisen in American nursing research.