Cardiopulmonary Resuscitation (CPR) is the foundational intervention of basic life support, designed to manually circulate blood and oxygen until the heart can be restarted. When trained medical personnel arrive, care progresses to Advanced Cardiovascular Life Support (ACLS), which includes securing the patient’s airway. The Endotracheal (ET) tube is the preferred method for advanced airway management during cardiac arrest, allowing for precise control over oxygen delivery and ventilation. This specialized technique fundamentally alters the mechanics of CPR, shifting the focus to continuous, uninterrupted chest compressions. The placement of an ET tube enables a more coordinated approach between the two primary components of CPR: circulation and ventilation.
The Role of the Endotracheal Tube in Resuscitation
An endotracheal tube is a flexible tube inserted directly into the trachea, or windpipe, to establish a secure and sealed pathway for breathing. During resuscitation, this device protects the lungs from aspiration, preventing stomach contents or fluids from entering the airway. The sealed system created by the tube and its inflatable cuff ensures that delivered oxygen reaches the lungs efficiently, maximizing gas exchange during cardiac arrest.
The ET tube allows rescuers to separate the timing of compressions from ventilations, eliminating the need to pause chest compressions to deliver breaths. This continuous circulation is a major benefit, as any interruption to compressions can decrease the blood flow necessary to sustain the brain and heart muscle.
Maintaining Continuous Chest Compressions
The most significant procedural change after securing an advanced airway is the switch from the standard 30:2 compression-to-ventilation ratio to continuous chest compressions. Once the ET tube is correctly placed, the rescuer performing compressions no longer needs to stop for breaths. This maximizes the time the heart and brain receive blood flow, which is the goal of high-quality CPR.
Compressions should be delivered at a rate of 100 to 120 compressions per minute, maintaining a depth of at least two inches in adult patients. The ability to perform compressions without any interruption is vital, as every pause reduces coronary perfusion pressure, decreasing the likelihood of a successful outcome. Minimizing interruptions sustains the limited blood flow to the body’s most oxygen-sensitive organs.
Specifics of Ventilation Delivery
With an ET tube in place, the ventilation strategy becomes asynchronous, meaning the breaths are delivered independently of the chest compressions. The recommended ventilation rate is one breath every six seconds, which equates to approximately 10 breaths per minute. This specific timing is used to avoid hyperventilation, a potentially detrimental mistake in advanced resuscitation.
Delivering breaths too frequently or with excessive volume increases the pressure inside the chest cavity, known as intrathoracic pressure. This increased pressure compresses the major veins, significantly impairing the return of blood to the heart between compressions. When venous return is reduced, the amount of blood the heart can pump out decreases, directly undermining the effectiveness of the chest compressions. The slow, controlled rate of 10 breaths per minute is a deliberate measure to balance the need for oxygenation with the maintenance of optimal circulatory dynamics.
Confirming Tube Placement During CPR
Immediately following the insertion of an endotracheal tube, its correct placement within the trachea must be verified. The most reliable method for this confirmation is quantitative waveform capnography, which non-invasively measures the partial pressure of carbon dioxide (CO2) in the patient’s exhaled breath. Exhaled CO2, known as end-tidal CO2 or EtCO2, is produced by the body’s metabolism and transported to the lungs by the blood.
A clearly visible, sustained waveform provides definitive evidence that the tube is correctly positioned in the airway. This measurement also serves as a real-time indicator of the quality of chest compressions; a low EtCO2 value (typically below 10 mmHg) suggests compressions are not circulating enough blood to the lungs. A sudden and sustained increase in the EtCO2 level is one of the earliest and most reliable signs that the patient has experienced a Return of Spontaneous Circulation (ROSC).