Chapter 29 — Laboratory Monitoring

Published 2026-09-22. 16 sections, 31 callouts, 9 tables, ~91 kB. Organising insight: every assay was validated by changing one variable at a time; an ECMO patient changes everything at once (Saifee ASAIO J 2020 — anti-Xa r=0.97 with heparin, PT r=0.88 with factors, ACT r=0.99 with factors and insensitive to heparin below 0.5 U/mL). Second structural claim: haemolysis is also an assay interferent, so the patient who is haemolysing is the one in whom the anticoagulation test is least reliable. Controversy 1: ELSO 50 mg/dL is a definition, not a safety margin (Saeed Ann Thorac Surg 2019, aHR 7.6 for non-haemorrhagic stroke at 11-50 mg/dL, graded). Controversy 2: lower flow and haemolysis (Costantini Perfusion 2022) — resolved as probable confounding by indication. Four numeric disagreements between the book's own primary sources recorded and flagged, none silently corrected; owed to Ch 42. Scope gap found: no chapter owns the pre-cannulation laboratory panel — owed to Ch 14 and the VV initiation chapters. Ch 55 owed the circuit-connected CRRT haemolysis finding; Ch 88 owed the panel and the daily phlebotomy volume.