The Bag-Valve-Mask (BVM) device, sometimes referred to as an Ambu bag, is a handheld resuscitator used to provide positive pressure ventilation to patients who are not breathing or are breathing inadequately. This device consists of a self-inflating bag, a one-way valve, and a face mask designed to cover the patient’s nose and mouth. The purpose of the BVM is to manually force air or oxygen into the lungs, a procedure often necessary during respiratory failure or cardiac arrest.
The Critical Difference Between One and Two Operators
While a single person can technically operate a Bag-Valve-Mask, the standard for achieving optimal ventilation requires two operators. The primary difficulty in BVM ventilation is the simultaneous need to maintain an open airway and create an airtight seal between the mask and the patient’s face. If the mask seal is poor, the positive pressure delivered by squeezing the bag leaks out rather than entering the lungs. The rescuer must also physically displace the jaw to lift the tongue away from the back of the throat, preventing airway obstruction. Separating these complex tasks between two individuals is why the two-person method is preferred.
The Single-Operator Technique and Limitations
A lone rescuer performing BVM ventilation must manage both the mask seal and the bag compression with only two hands, which severely limits effectiveness. The rescuer typically uses one hand to maintain the airway and the mask seal, employing the one-handed C-E grip. In this method, the thumb and index finger form a “C” shape over the mask, while the remaining three fingers form an “E” shape under the jawbone to lift the face and open the airway. The limitation of this technique is the inability to apply enough consistent force to achieve an effective, leak-free seal. Studies show the single-person technique results in a high percentage of air leakage, often failing to deliver adequate tidal volumes.
Complications of Single-Operator Use
When insufficient air enters the lungs, the rescuer often squeezes the bag harder to compensate. This increases the risk of forcing air into the stomach, a complication known as gastric insufflation. Gastric insufflation can lead to vomiting and subsequent aspiration, making the single-operator approach suboptimal for prolonged or difficult ventilations.
Optimizing Ventilation With a Two-Person Team
The two-person BVM technique is considered the gold standard because it effectively divides the labor into two distinct, manageable roles. The first operator, positioned at the patient’s head, is solely responsible for managing the airway and maintaining the mask seal. Using both hands allows for maximum force and leverage to be applied to the seal and the jaw. This two-handed approach enables advanced techniques like the double C-E grip or the preferred two-thumbs-up technique (V-E clamp). The second operator focuses exclusively on the bag, squeezing it with precise timing and volume. This division of labor provides higher mean tidal volumes and significantly lower mask leakage, leading to more effective ventilation.