Heterogeneity and Coordination of Blood Pressure in Neurosurgery

Abstract

Blood pressure is one of the key measurements taken in standard clinical examinations. Its importance has long been associated with the instrumental precision offered by the sphygmomanometer, which is supposed to have replaced other, more imprecise methods of blood pressure measurement, such as feeling the pulse with the finger. Drawing on ethnographic fieldwork in a neurosurgical clinic, this paper explores the co-existence of the sphygmomanometer and the finger methods in practice. I argue that in neurosurgery these methods are both independent from and interdependent with each other: independent in the way they achieve different assessments of the patient’s blood pressure at the same time; and interdependent in the way the surgeon’s and anaesthetist’s measurements are dynamically linked with each other. The paper suggests that this particular form of coordination through heterogeneity might be described, borrowing from Michel Serres’ work, as mutual parasitism, and that this metaphor might be useful in rethinking the role of science - research, or ‘evidence’ - in medical practice.