How often should the casualty be ventilated once a seal is established using the "E-C" technique?

Once a seal is established using the "E-C" technique for ventilation, the recommended frequency is every 5-6 seconds. This timing allows for effective ventilation without overwhelming the patient. It ensures that the casualty receives enough air and facilitates adequate oxygenation and ventilation in case of respiratory distress. Ventilating too quickly could lead to complications such as increased intrathoracic pressure, decreased venous return to the heart, and potential hyperventilation, which can lower carbon dioxide levels to dangerous thresholds. Therefore, 5-6 seconds strikes a balance between providing sufficient oxygen and minimizing the risk of adverse effects during resuscitation efforts.