Bag-valve masks (BVMs) provide breathing support during medical emergencies, delivering oxygen to individuals who cannot breathe adequately. Using an adult-sized device on an infant poses significant risks. Understanding the differences in infant physiology and equipment design underscores the necessity of employing the correct tools for safe and effective care.
Fundamental Differences in Infant Respiration
An infant’s respiratory system differs significantly from an adult’s, making them vulnerable during ventilation. Infants have smaller lung volumes and more compliant, easily overstretched lung tissue, lacking the structural maturity found in adult lungs.
Infant airways are smaller and more flexible, increasing their susceptibility to collapse or obstruction. Infants also exhibit a higher respiratory rate and greater metabolic demands relative to their body size. Their respiratory drive is immature, sometimes leading to irregular breathing patterns. These distinctions explain why infants are more prone to respiratory distress and injury.
Equipment Design Mismatch
The design of adult BVMs is incompatible with an infant’s delicate respiratory system. An adult BVM delivers a significantly larger volume of air per squeeze than an infant’s tiny lungs can safely accommodate. Adult BVMs typically have reservoir volumes ranging from 1500–2000 mL, with stroke volumes of 900–1000 mL, whereas pediatric BVMs range from 500–1000 mL with stroke volumes of 450–650 mL. This difference makes it challenging to deliver the precise, small volumes required for an infant.
Adult BVMs often lack an appropriate pressure relief valve or have one set at a higher pressure than is safe for infants. Infant-specific bags include a pressure relief valve calibrated to prevent excessive pressure (usually between 30-45 cm H2O) to protect fragile infant lungs. Adult masks are too large to achieve a proper seal over an infant’s face, leading to air leaks. The resistance and compliance characteristics of an adult bag and valve system are not optimized for an infant’s airway structures.
Serious Risks of Improper Ventilation
Using an adult BVM on an infant can lead to serious complications. One risk is barotrauma, injury to the lungs caused by excessive pressure. This can result in a pneumothorax (air leaks into the space between the lung and chest wall, causing the lung to collapse) or pneumomediastinum (air enters the mediastinum). Another danger is volutrauma, lung injury caused by excessive air volume, leading to overdistension and damage.
Gastric insufflation, where air is forced into the stomach instead of the lungs, is a common concern. This can cause abdominal distension, vomiting, and an increased risk of aspiration (stomach contents entering the lungs). Ineffective ventilation can occur due to an improper mask seal from an oversized mask, leading to air leaks and inadequate oxygen delivery, which can result in hypoxemia (low blood oxygen levels) or hypercapnia (excessive carbon dioxide retention).
Hyperventilation (delivering too many breaths or too much volume) can cause hypocapnia, a reduction in carbon dioxide levels in the blood. This can lead to vasoconstriction, reducing blood flow to the brain. High intrathoracic pressure can also impede venous return to the heart, negatively affecting cardiac output and compromising the infant’s cardiovascular system.
The Criticality of Correct Equipment
Employing appropriately sized pediatric or infant BVMs and masks is important for safe and effective ventilation. These specialized devices are designed with the unique physiology of an infant in mind. They feature smaller bag volumes to deliver precise amounts of air and often incorporate pressure-relief valves to prevent lung injury.
Properly sized masks ensure a secure seal over the infant’s face, preventing air leaks and ensuring effective oxygen delivery. The correct use of these specialized tools, along with proper training in pediatric basic life support, is essential for providing appropriate and life-saving respiratory support for infants.