title: Comparison of different inspiratory triggering settings in automated ventilators during cardiopulmonary resuscitation in a porcine model.
abstract: BACKGROUND
  Mechanical ventilation via automated in-hospital ventilators is quite common during cardiopulmonary resuscitation. It is not known whether different inspiratory triggering sensitivity settings of ordinary ventilators have different effects on actual ventilation, gas exchange and hemodynamics during resuscitation.
  
  
  METHODS
  18 pigs enrolled in this study were anaesthetized and intubated. Continuous chest compressions and mechanical ventilation (volume-controlled mode, 100% O2, respiratory rate 10/min, and tidal volumes 10ml/kg) were performed after 3 minutes of ventricular fibrillation. Group trig-4, trig-10 and trig-20 (six pigs each) were characterized by triggering sensitivities of 4, 10 and 20 (cmH2O for pressure-triggering and L/min for flow-triggering), respectively. Additionally, each pig in each group was mechanically ventilated using three types of inspiratory triggering (pressure-triggering, flow-triggering and turned-off triggering) of 5 minutes duration each, and each animal matched with one of six random assortments of the three different triggering settings. Blood gas samples, respiratory and hemodynamic parameters for each period were all collected and analyzed.
  
  
  RESULTS
  In each group, significantly lower actual respiratory rate, minute ventilation volume, mean airway pressure, arterial pH, PaO2, and higher end-tidal carbon dioxide, aortic blood pressure, coronary perfusion pressure, PaCO2 and venous oxygen saturation were observed in the ventilation periods with a turned-off triggering setting compared to those with pressure- or flow- triggering (all P<0.05), except when compared with pressure-triggering of 20 cmH2O (respiratory rate 10.5[10/11.3]/min vs 12.5[10.8/13.3]/min, P = 0.07; coronary perfusion pressure 30.3[24.5/31.6] mmHg vs 27.4[23.7/29] mmHg, P = 0.173; venous oxygen saturation 46.5[32/56.8]% vs 41.5[33.5/48.5]%, P = 0.575).
  
  
  CONCLUSIONS
  Ventilation with pressure- or flow-triggering tends to induce hyperventilation and deteriorating gas exchange and hemodynamics during CPR. A turned-off patient triggering or a pressure-triggering of 20 cmH2O is preferred for ventilation when an ordinary inpatient hospital ventilator is used during resuscitation.
authors.affiliation: Department of Emergency, Peking Union Medical College Hospital, Chinese Academy of Medical sciences, Beijing, China.
authors.forename: Dingyu
authors.initials: D
authors.lastname: Tan
authors.affiliation: Department of Emergency, Peking Union Medical College Hospital, Chinese Academy of Medical sciences, Beijing, China.
authors.forename: Jun
authors.initials: J
authors.lastname: Xu
authors.affiliation: Department of Emergency, Peking Union Medical College Hospital, Chinese Academy of Medical sciences, Beijing, China.
authors.forename: Shihuan
authors.initials: S
authors.lastname: Shao
authors.affiliation: Department of Emergency, Peking Union Medical College Hospital, Chinese Academy of Medical sciences, Beijing, China.
authors.forename: Yangyang
authors.initials: Y
authors.lastname: Fu
authors.affiliation: Department of Emergency, Peking Union Medical College Hospital, Chinese Academy of Medical sciences, Beijing, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Sun
authors.affiliation: Department of Emergency, Peking Union Medical College Hospital, Chinese Academy of Medical sciences, Beijing, China.
authors.forename: Yazhi
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Emergency, Peking Union Medical College Hospital, Chinese Academy of Medical sciences, Beijing, China.
authors.forename: Yingying
authors.initials: Y
authors.lastname: Hu
authors.affiliation: Division of Emergency Medicine, Department of Surgery, Saint Louis University Hospital, Saint Louis, Missouri.
authors.forename: Joseph
authors.initials: J
authors.lastname: Walline
authors.affiliation: Department of Emergency, Peking Union Medical College Hospital, Chinese Academy of Medical sciences, Beijing, China.
authors.forename: Huadong
authors.initials: H
authors.lastname: Zhu
authors.affiliation: Department of Emergency, Peking Union Medical College Hospital, Chinese Academy of Medical sciences, Beijing, China.
authors.forename: Xuezhong
authors.initials: X
authors.lastname: Yu
mesh_terms: D000818:Animals; D016887:Cardiopulmonary Resuscitation / Q000295:instrumentation* / Q000379:methods; D006439:Hemodynamics; D001239:Inhalation; D012123:Pulmonary Ventilation; D013552:Swine; D012122:Ventilators, Mechanical / Q000009:adverse effects*; D014693:Ventricular Fibrillation / Q000628:therapy