Agonal respiration

Abstract: Purpose of review This review examines the clinical significance of agonal respirations associated with cardiac arrest. Recent findings Observational data indicate that agonal respirations are frequent (55% of witnessed cardiac arrests and probably higher) and that they are associated with successful resuscitation. They also are found more commonly in ventricular fibrillation compared with other rhythms. Agonal respirations pose the greatest challenge to bystanders at the scene and to emergency dispatchers. Bystanders are often lulled into thinking the person is still breathing thus identification of cardiac arrest may be missed by the dispatcher. In a study from King County, Washington, cardiopulmonary resuscitation instructions were not provided by emergency dispatchers in 20% of cardiac arrest cases because the caller reported signs of life - typically abnormal breathing. Summary Agonal respirations occur frequently in cardiac arrest. Emergency dispatchers and the general public must be more aware of their presence and significance.

Abstract: Objective: To describe ventilator dynamics following the onset of ventricular fibrillation (VF) in an experimental swine model. Methods: Twelve female mixed-breed domestic swine (mean mass 21.3 2 1.7 kg) were sedated with IM ketamine (10 mag) and xylazine (1 mgntg), anesthetized with α-chloralose (40 mgkg loading dose, 10 mg/kg/hr rnaintenance infusion), incubated, and mechanically ventilated on room air. ECG, and aortic and pulmonary artery pressures were monitored continuously. VF was induced with a 3-sec, 60-Hz, 100-mA Tran thoracic shock, and left untreated for 8 minutes. Respiratory rate, tidal volume, and minute ventilation were recorded until respiratory activity ceased. Results: All 12 animals (100%) had agonal respirations through the first 2 minutes of arrest. This decreased to 11 (92%) at minute 3, five (42%) at minute 4, and two (17%) at minute 7. Mean respiratory rates ranged from 6 to 11 breathdmin. Mean tidal volumes ranged from 502 to 852 mL. Mean minute ventilations ranged from 3.3 to 5.8 L. Conclusion: In this swine model, 11 of 12 (92%) continued to have spontaneous agonal respirations for the first 3 minutes of VF cardiac arrest. Many animals had supernormal tidal volumes, and near-normal minute ventilations. These findings have potential implications for lay-rescuer and first-responder contributions to resuscitation of victims of out-of-hospital cardiac arrest.

Abstract: We modified the dispatch protocol for cardiopulmonary resuscitation (CPR) using results of a retrospective analysis that identified descriptions by laypersons of possible patterns of agonal respiration. The purpose of this study was to assess the effectiveness of this modified protocol by comparing the frequency of dispatch instructions for CPR and bystander CPR before and after protocol implementation. We also identified descriptions of abnormal breathing patterns among ‘Not in cardiac arrest (CA)’ unresponsive cases. This study was conducted prospectively using the population-based registry of out-of-hospital cardiac arrests (OHCAs). For 8 months we implemented this modified protocol in cooperation with 4 fire departments that cover regions with a total population of 840,000. There were 478 and 427 OHCAs before and after implementation, respectively. Among them, 69 and 71 layperson-witnessed OHCAs for pre- and post-implementation, respectively, were analyzed. Dispatchers provided CPR instructions more frequently after protocol implementation than before (55/71 [77.5 %] vs. 41/69 [59.4 %], p < 0.05). Based on breathing patterns described by emergency callers, dispatchers assessed 143 ‘Not in CA’ unresponsive cases and provided CPR instruction for 45 cases. Sensitivity and specificity of this protocol was 93 % and 50 %, respectively. This modified protocol based on abnormal breathing described by laypersons significantly increased CPR instructions. Considering high sensitivity and low specificity for abnormal breathing to identify CA and the low risk of chest compression for ‘Not in CA’ cases, our study suggested that dispatchers can provide CPR instruction assertively and safely for those unresponsive individuals with various abnormal breathing patterns.