title: Transthoracic impedance for the monitoring of quality of manual chest compression during cardiopulmonary resuscitation.
abstract: OBJECTIVE
  The quality of cardiopulmonary resuscitation (CPR), especially adequate compression depth, is associated with return of spontaneous circulation (ROSC) and is therefore recommended to be measured routinely. In the current study, we investigated the relationship between changes of transthoracic impedance (TTI) measured through the defibrillation electrodes, chest compression depth and coronary perfusion pressure (CPP) in a porcine model of cardiac arrest.
  
  
  METHODS
  In 14 male pigs weighing between 28 and 34 kg, ventricular fibrillation (VF) was electrically induced and untreated for 6 min. Animals were randomized to either optimal or suboptimal chest compression group. Optimal depth of manual compression in 7 pigs was defined as a decrease of 25% (50 mm) in anterior posterior diameter of the chest, while suboptimal compression was defined as 70% of the optimal depth (35 mm). After 2 min of chest compression, defibrillation was attempted with a 120-J rectilinear biphasic shock.
  
  
  RESULTS
  There were no differences in baseline measurements between groups. All animals had ROSC after optimal compressions; this contrasted with suboptimal compressions, after which only 2 of the animals had ROSC (100% vs. 28.57%, p=0.021). The correlation coefficient was 0.89 between TTI amplitude and compression depth (p<0.001), 0.83 between TTI amplitude and CPP (p<0.001).
  
  
  CONCLUSIONS
  Amplitude change of TTI was correlated with compression depth and CPP in this porcine model of cardiac arrest. The TTI measured from defibrillator electrodes, therefore has the potential to serve as an indicator to monitor the quality of chest compression and estimate CPP during CPR.
authors: Institute of Surgery Research, Daping Hospital, Third Military Medical University, Chongqing, China.
authors: Hehua
authors: H
authors: Zhang
authors: Zhengfei
authors: Z
authors: Yang
authors: Zitong
authors: Z
authors: Huang
authors: Bihua
authors: B
authors: Chen
authors: Lei
authors: L
authors: Zhang
authors: Heng
authors: H
authors: Li
authors: Baoming
authors: B
authors: Wu
authors: Tao
authors: T
authors: Yu
authors: Yongqin
authors: Y
authors: Li
mesh_terms: D000818:Animals; D002307:Cardiography, Impedance; D016887:Cardiopulmonary Resuscitation / Q000379:methods* / Q000592:standards*; D008297:Male; D011786:Quality Control; D013552:Swine; D013909:Thorax