Section 3: Adjuncts for Oxygenation, Ventilation, and Airway Control Oxygenation Devices

Oxygenation Devices During cardiopulmonary emergencies use supplemental oxygen as soon as it is available. Rescue breathing (ventilation using exhaled air) will deliver approximately 16% to 17% inspired oxygen concentration to the patient, ideally producing an alveolar oxygen tension of 80 mm Hg. During cardiac arrest and CPR, tissue hypoxia occurs because of low cardiac output with reduced peripheral oxygen delivery and a resulting wide arteriovenous oxygen difference. Additional factors that cause hypoxia are intrapulmonary shunting with attendant ventilation-perfusion abnormalities and underlying respiratory disease. Tissue hypoxia leads to anaerobic metabolism and metabolic acidosis. Acid-base imbalance frequently blunts the beneficial effects of chemical and electrical therapy. For these reasons 100% inspired oxygen (FiO251.0) is recommended during BLS and ACLS when available. High inspired oxygen tensions will tend to maximize arterial blood oxygen saturation and, in turn, systemic oxygen delivery (cardiac output 3 blood oxygen content). Short-term therapy with 100% oxygen is beneficial and not toxic. Oxygen toxicity occurs during prolonged therapy with a high FiO2. In patients with acute MI, supplemental oxygen reduces both the magnitude and the extent of ST-segment changes on the ECG. We recommend oxygen administered at 4 L/min by nasal cannula for the first 2 to 3 hours for all patients with suspected acute coronary syndromes (Class IIa). The use of oxygen beyond 3 to 6 hours is indicated for patients with continuing or recurrent ischemia, complicated infarcts with congestive heart failure, or arrhythmia until hypoxemia has resolved and the patient is clinically stable.