Systemic vascular resistance

Method

Systemic vascular resistance calculated from the standard haemodynamic formula using invasively or non-invasively measured perfusion pressures and cardiac output, with the cardiac output method (thermodilution, pulse contour analysis, echocardiography) recorded on the edge.

The method is part of the endpoint identity. Studies measuring the same quantity by a different method are held as separate endpoints.

Notes

Direction of benefit is context-bound and is set here for the vasoplegic and distributive shock literature these papers come from, where a pathologically low resistance is the lesion and restoring it is the benefit; IN A HYPERTENSION OR HEART-FAILURE POPULATION THE SAME NUMBER IMPROVES BY FALLING, so an edge without the population recorded has an indeterminate sign. Not independent of CAT:outcome/mean-arterial-pressure or of cardiac output - it is computed from both - so an edge on this plus an edge on either input from one trial double-counts a single haemodynamic observation.