Open Access Open Badges Research article

Continued breathing followed by gasping or apnea in a swine model of ventricular fibrillation cardiac arrest

Mathias Zuercher12, Gordon A Ewy13*, Ronald W Hilwig1, Arthur B Sanders14, Charles W Otto135, Robert A Berg6 and Karl B Kern13

Author Affiliations

1 University of Arizona Sarver Heart Center, Tucson, AZ, USA

2 Department of Anesthesia and Intensive Care Medicine, University Hospital Basel, Basel, Switzerland

3 Department of Medicine, University of Arizona College of Medicine, Tucson, AZ, USA

4 Department of Emergency Medicine, University of Arizona College of Medicine, Tucson, AZ, USA

5 Department of Anesthesiology, University of Arizona College of Medicine, Tucson, AZ, USA

6 Department of Anesthesia and Critical Care, The Children's Hospital of Philadelphia, Philadelphia, PA, USA

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BMC Cardiovascular Disorders 2010, 10:36  doi:10.1186/1471-2261-10-36

Published: 9 August 2010



Continued breathing following ventricular fibrillation has here-to-fore not been described.


We analyzed the spontaneous ventilatory activity during the first several minutes of ventricular fibrillation (VF) in our isoflurane anesthesized swine model of out-of-hospital cardiac arrest. The frequency and type of ventilatory activity was monitored by pneumotachometer and main stream infrared capnometer and analyzed in 61 swine during the first 3 to 6 minutes of untreated VF.


During the first minute of VF, the air flow pattern in all 61 swine was similar to those recorded during regular spontaneous breathing during anesthesia and was clearly different from the patterns of gasping. The average rate of continued breathing during the first minute of untreated VF was 10 breaths per minute. During the second minute of untreated VF, spontaneous breathing activity either stopped or became typical of gasping. During minutes 2 to 5 of untreated VF, most animals exhibited very slow spontaneous ventilatory activity with a pattern typical of gasping; and the pattern of gasping was crescendo-decrescendo, as has been previously reported. In the absence of therapy, all ventilatory activity stopped 6 minutes after VF cardiac arrest.


In our swine model of VF cardiac arrest, we documented that normal breathing continued for the first minute following cardiac arrest.