Arterial blood pressure; BP, blood pressure (invasive arterial); BVI, blood volume index; CA, cardiac arrest; CI, confidence interval; CPR, cardiopulmonary resuscitation; CSF, cerebrospinal fluid; Cardiopulmonary resuscitation; CoSTR, consensus on science with treatment recommendations; ECG, electrocardiogram; ECMO, extracorporeal membrane oxygenation; ECPR, extracorporeal cardiopulmonary resuscitation; ED, emergency department; End-tidal CO2; EtCO2, end-tidal carbon dioxide; ICP, intracranial pressure; IHCA, in-hospital cardiac arrest; ILCOR, international liaison committee on resuscitation; NICU, neonatal intensive care unit; NIRS, near-infrared spectroscopy; Near-infrared spectroscopy; OHCA, out-of-hospital cardiac arrest; OR, odds ratio; PCICU, paediatric cardiac intensive care unit; PE, pulmonary emboli; PICU, paediatric intensive care unit; PRISMA, preferred reporting items for systematic reviews and meta-analyses; Paediatric life support; Point-of-care ultrasound; RCT, randomized controlled trial; ROC, receiver operating characteristic; ROSC, return of spontaneous circulation; RR, relative risk; RV, right ventricle; SD, standard deviation; USA, United States of America; rcSO2, regional cerebral oxygen saturations