title: Bedside focused echocardiography as predictor of survival in cardiac arrest patients: a systematic review.
abstract: OBJECTIVE
  The objective was to determine if focused transthoracic echocardiography (echo) can be used during resuscitation to predict the outcome of cardiac arrest.
  
  
  METHODS
  A literature search of diagnostic accuracy studies was conducted using MEDLINE via PubMed, EMBASE, CINAHL, and Cochrane Library databases. A hand search of references was performed and experts in the field were contacted. Studies were included for further appraisal and analysis only if the selection criteria and reference standards were met. The eligible studies were appraised and scored by two independent reviewers using a modified quality assessment tool for diagnostic accuracy studies (QUADAS) to select the papers included in the meta-analysis.
  
  
  RESULTS
  The initial search returned 2,538 unique papers, 11 of which were determined to be relevant after screening criteria were applied by two independent researchers. One additional study was identified after the initial search, totaling 12 studies to be included in our final analysis. The total number of patients in these studies was 568, all of whom had echo during resuscitation efforts to determine the presence or absence of kinetic cardiac activity and were followed up to determine return of spontaneous circulation (ROSC). Meta-analysis of the data showed that as a predictor of ROSC during cardiac arrest, echo had a pooled sensitivity of 91.6% (95% confidence interval [CI] = 84.6% to 96.1%), and specificity was 80.0% (95% CI = 76.1% to 83.6%). The positive likelihood ratio for ROSC was 4.26 (95% CI = 2.63 to 6.92), and negative likelihood ratio was 0.18 (95% CI = 0.10 to 0.31). Heterogeneity of the results (sensitivity) was nonsignificant (Cochran's Q: χ(2)  = 10.63, p = 0.16, and I(2)  = 34.1%).
  
  
  CONCLUSIONS
  Echocardiography performed during cardiac arrest that demonstrates an absence of cardiac activity harbors a significantly lower (but not zero) likelihood that a patient will experience ROSC. In selected patients with a higher likelihood of survival from cardiac arrest at presentation, based on established predictors of survival, echo should not be the sole basis for the decision to cease resuscitative efforts. Echo should continue to be used only as an adjunct to clinical assessment in predicting the outcome of resuscitation for cardiac arrest.
authors.affiliation: Dalhousie Medicine New Brunswick, Saint John, New Brunswick.
authors.forename: Lacey
authors.initials: L
authors.lastname: Blyth
authors.forename: Paul
authors.initials: P
authors.lastname: Atkinson
authors.forename: Kathleen
authors.initials: K
authors.lastname: Gadd
authors.forename: Eddy
authors.initials: E
authors.lastname: Lang
mesh_terms: D016887:Cardiopulmonary Resuscitation / Q000379:methods*; D004452:Echocardiography / Q000379:methods*; D006323:Heart Arrest / Q000000981:diagnostic imaging* / Q000401:mortality / Q000628:therapy; D006801:Humans; D019095:Point-of-Care Systems; D012680:Sensitivity and Specificity