title: Systematic review of the mechanisms driving effective blood flow during adult CPR.
abstract: BACKGROUND
  High quality chest compressions is the most significant factor related to improved short-term and long-term outcome in cardiac arrest. However, considerable controversy exists over the mechanisms involved in driving blood flow.
  
  
  OBJECTIVE
  The aim of this systematic review is to elucidate major mechanisms involved in effective compression-mediated blood flow during adult cardiopulmonary resuscitation (CPR).
  
  
  METHODS
  Systematic review of studies identified from the bibliographic databases of PubMed/Medline, Cochrane, and Scopus.
  
  
  METHODS
  All human and animal studies including information on the responsible mechanisms of compression-related blood flow.
  
  
  METHODS
  Two reviewers (MG, TX) independently screened all potentially relevant titles and abstracts for eligibility, by using a standardized data-worksheet.
  
  
  RESULTS
  Forty seven studies met the inclusion criteria. Because of the heterogeneity in outcome measures, quantitative synthesis of evidence was not feasible. Evidence was critically synthesized in order to answer the review questions, taking into account study heterogeneity and validity. The number of included studies per category is as follows: blood flow during chest compression, nine studies; blood flow during chest decompression, six studies; effect of chest compression on cerebral blood flow, eight studies; active compression-decompression CPR, 14 studies; and effect of ventilation on compression-related blood flow, 13 studies.
  
  
  CONCLUSIONS
  The evidence so far is inconclusive regarding the major responsible mechanism in compression-related blood flow. Although both 'cardiac pump' and 'thoracic pump' have a key role, the effect of each mechanism is highly depended on other resuscitation parameters, such as positive pressure ventilation and compression depth.
authors.affiliation: Nursing, American Medical Center, Nicosia, Cyprus; Cyprus Resuscitation Council, Nicosia, Cyprus.
authors.forename: Marios
authors.initials: M
authors.lastname: Georgiou
authors.affiliation: Cyprus Resuscitation Council, Nicosia, Cyprus; School of Health Sciences, Cyprus Technological University of Technology, Nicosia, Cyprus.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Papathanassoglou
authors.affiliation: National and Kapodistrian University of Athens, Medical School, Athens, Greece; Hellenic Society of Cardiopulmonary Resuscitation, Athens, Greece. Electronic address: theodorosxanthos@yahoo.com.
authors.forename: Theodoros
authors.initials: T
authors.lastname: Xanthos
mesh_terms: D000328:Adult; D000818:Animals; D001783:Blood Flow Velocity / Q000502:physiology; D016887:Cardiopulmonary Resuscitation / Q000379:methods* / Q000401:mortality; D002560:Cerebrovascular Circulation / Q000502:physiology; D004195:Disease Models, Animal; D004285:Dogs; D005260:Female; D006323:Heart Arrest / Q000175:diagnosis / Q000401:mortality / Q000628:therapy*; D006336:Heart Massage / Q000379:methods* / Q000401:mortality; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D008297:Male; D011379:Prognosis; D012039:Regional Blood Flow / Q000502:physiology*; D015996:Survival Rate; D013552:Swine; D016896:Treatment Outcome
keywords: Blood flow; Cardiac arrest; Cardiopulmonary resuscitation; Chest compression