A Bag-Valve-Mask (BVM) device is a handheld tool used in emergencies to help a person breathe when they are unable to do so adequately on their own. Its primary role is to deliver air into the patient’s lungs, supporting their oxygen supply and carbon dioxide removal. Ensuring the correct volume of air is delivered with each ventilation is important for patient safety and the effectiveness of resuscitation efforts. This attention to air volume helps prevent complications and promotes positive patient outcomes.
Understanding Ventilation Goals
The main purpose of ventilation is to facilitate the movement of air into and out of the lungs, which is necessary for the body to take in oxygen and release carbon dioxide. Each breath moves a certain amount of air, a concept known as tidal volume. In emergency ventilation, the aim is to replicate natural breathing as closely as possible, providing just enough air to achieve proper oxygenation and carbon dioxide removal without causing harm to the patient’s lungs.
Achieving this balance is important because both too much and too little air can have negative consequences. The goal is to support the body’s gas exchange process efficiently. This ensures adequate oxygen delivery and effective carbon dioxide expulsion.
How to Determine the Right Air Volume
Determining the correct air volume for BVM ventilations relies on observing the patient’s physical response rather than a fixed numerical value. The primary indicator for adequate ventilation is slight chest rise. This means delivering just enough air to make the chest gently rise, and then allowing it to fall before the next breath. This principle applies across all age groups, though the actual amount of air needed will vary considerably based on patient size.
For an adult, the volume delivered should be sufficient to cause a slight and observable chest rise, typically ranging from 5 to 8 milliliters per kilogram of ideal body weight. For infants and young children, a self-inflating bag with a volume of at least 450 to 500 mL may be necessary to deliver an effective tidal volume and achieve chest rise. In older children or adolescents, an adult-sized self-inflating bag, which typically holds 1000 mL, might be needed to reliably achieve this chest rise. Over-inflating the lungs is a common mistake, which underscores the importance of focusing on gentle chest rise as the guide.
Risks of Improper Ventilation
Delivering an improper amount of air during BVM ventilation carries risks for the patient. Providing too much air, known as over-ventilation, can lead to several complications. One risk is gastric inflation, where air enters the stomach instead of the lungs, potentially causing vomiting and aspiration. Over-ventilation can also result in barotrauma, which is lung injury caused by excessive pressure.
Conversely, delivering too little air, or under-ventilation, also poses dangers. This can lead to inadequate oxygen delivery to the body’s tissues, a condition called hypoxia. Insufficient carbon dioxide removal is another risk, which can worsen the patient’s condition. Both scenarios highlight the importance of careful volume control to prevent further harm during resuscitation efforts.
Essential BVM Technique
Effective BVM ventilation depends on proper technique. An important element is a tight mask seal, which ensures that the delivered air enters the patient’s lungs and does not escape around the mask. For adults, ventilations should be delivered at a rate of approximately one breath every 5 to 6 seconds. Each breath should be delivered slowly and steadily, with a squeeze of the bag lasting about one second, allowing the air to gradually enter the lungs.
Throughout the ventilation process, it is important to continuously observe for a visible chest rise and fall with each breath. This visual confirmation ensures that the air is indeed reaching the lungs and that the correct volume is being delivered. If chest rise is not observed, the rescuer should reassess the mask seal and airway position before attempting another ventilation.