Background: During experimental cardiac arrest, continuous insufflation of air or oxygen (CIO) through microcannulas inserted into the inner wall of a modified intubation tube and generating a permanent positive intrathoracic pressure, combined with external cardiac massage, has previously been shown to be as effective as intermittent positive pressure ventilation (IPPV).
Methods: After basic cardiorespiratory resuscitation, the adult patients who experienced nontraumatic, out-of-hospital cardiac arrest with asystole, were randomized to two groups: an IPPV group tracheally intubated with a standard tube and ventilated with standard IPPV and a CIO group for whom a modified tube was inserted, and in which CIO at a flow rate of 15 l/min replaced IPPV (the tube was left open to atmosphere). Both groups underwent active cardiac compression-decompression with a device. Resuscitation was continued for a maximum of 30 min. Blood gas analysis was performed as soon as stable spontaneous cardiac activity was restored, and a second blood gas analysis was performed at admission to the hospital.
Results: The two groups of patients (47 in the IPPV and 48 in the CIO group) were comparable. The percentages of patients who underwent successful resuscitation (stable cardiac activity; 21.3 in the IPPV group and 27.1% in the CIO group) and the time necessary for successful resuscitation (11.8 +/- 1.8 and 12.8 +/- 1.9 min) were also comparable. The blood gas analysis performed after resuscitation (8 patients in the IPPV and 10 in the CIO group) did not show significant differences. The arterial blood gases performed after admission to the hospital and ventilation using a transport ventilator (seven patients in the IPPV group and six in the CIO group) showed that the partial pressure of arterial carbon dioxide (PaCO2) was significantly lower in the CIO group (35.7 +/- 2.1 compared with 72.7 +/- 7.4 mmHg), whereas the pH and the partial pressure of arterial oxygen (PaO2) were significantly higher (all P < 0.05).
Conclusions: Continuous insufflation of air or oxygen alone through a multichannel open tube was as effective as IPPV during out-of-hospital cardiac arrest. A significantly greater elimination of carbon dioxide and a better level of oxygenation in the group previously treated with CIO probably reflected better lung mechanics.