Forest plot depicting bias and 95% limits of agreement of studies comparing noninvasive arterial pressure monitoring with invasive arterial pressure monitoring. Boxes represent the bias and bars represent the 95% limits of agreement. Heterogeneity was assessed by I²  for bias of included studies. Ilies^*, during induction; Ilies^**, during maintenance; Ilies^***, hypotensive induction; Ilies^****, hypotensive maintenance; Hahn^†, version 3.0; Hahn^††, version 3.5; Bardoczky^‡, one-lung ventilation; Bardoczky^‡‡, two-lung ventilation; Kurki^§, before CPB; Kurki^§§, during CPB; Kurki^§§§, after CPB. CPB = cardiopulmonary bypass; DAP = diastolic arterial pressure; MAP = mean arterial pressure; SAP = systolic arterial pressure.