The Dangers of Bag Valve Devices
Utilizing a bag valve device to ventilate has been the standard of care in
the pre-hospital environment for the last 50 years. However, because a bag valve device requires constant and
steady manual pumping by the operator, it does not guarantee consistent air delivery. As a result, bag valve
device resuscitation has been linked to a high incidence of hyperventilation, which adversely affects cardiac
arrest patients, patients with traumatic brain injury, and patients in shock. Bag valve devices have also
been linked to gastric insufflation. A new device that mitigates the potential for injury, reduces operator
error, complies with guidelines, and improves the medical responder’s ability to perform other critical tasks
is urgently needed. Ventilating a patient using a bag valve device requires significant concentration and
skill in stressful situations. With every squeeze of the bag, the rescuer is selecting the respiratory rate
and tidal volume. This can be extremely difficult for even the most highly trained professional: Keeping
artificial ventilation rates low is difficult because the high-adrenaline state of the rescuer alters time
perception, and the rapidly refilling bag–ventilation systems set up a reflex in which rescuers are inclined
to deliver breaths as soon as the bag inflates.
Cardiac Arrest
A clinical study observing ventilation rates in cardiac arrest patients
found that emergency medical services (EMS) rescuers who were trained to follow the American Heart
Association (AHA) guidelines were delivering on average 37±4 breaths per minute, not the 10–12 breaths per
minute prescribed by the guidelines. Even after the rescuers were re-trained to deliver 12 breaths per
minute, they were observed delivering an average of 22±3 breaths per minute.
To test the impact of hyperventilation, the same study investigated a
swine model with ventilation delivered at either 12 or 30 breaths per minute. Six out of seven animals in the
group that received 12 breaths per minute survived, while only one of seven that were hyperventilated
survived: a 70% reduction in absolute survival. Hyperventilation results in high intrathoracic pressure
during the decompression phase of cardiopulmonary resuscitation (CPR), which decreases cardiac pre-load and
cardiac output and impedes right ventricular function. Increased tidal volume is also known to adversely
affect cardiac output. The authors of the study believe that “the elevated mean intrathoracic pressures
caused by excessive ventilation inhibited Ventilating a patient using a bag valve device requires significant
concentration and skill in stressful situations. Ventilating a patient using a bag valve device requires
significant concentration and skill in stressful situations. “Keeping artificial ventilation rates low is
difficult because the high adrenaline state of the rescuer alters time perception…” pre-hospital environment
are limited. However, it is important that the rescuer does not
cause further injury by unduly elevating intracranial pressure (ICP) during positive-pressure ventilation.
Positive-pressure ventilation increases intrathoracic pressure and ICP. Hyperventilating a patient or
delivering excessive tidal volumes could be disastrous, as elevated ICP is a leading cause of secondary brain
injury.
Hemorrhagic Shock
“Even after moderate levels of hemorrhage in animals, positive-pressure
ventilation with normal or higher respiratory rates can impair hemodynamics.” Some investigators have now begun to question “the notion that severity of
injury is the lone factor leading to worse outcomes and, in turn, have raised the issue that overzealous
ventilation may also be a contributory factor.” Excessive ventilation raises the mean intrathoracic pressure,
which impedes venous return and decreases pre-load, stroke volume, and, consequently, cardiac output. During
shock, the body’s natural response is to recruit blood volume to the vital organs. Increased intrathoracic
pressure associated with excessive positive-pressure ventilation impedes this
process.
Gastric Insufflation
Gastric insufflation is a major concern when ventilating through an
unprotected airway. A study measuring the differences between a bag valve device and a transport ventilator
used with a mask found that “almost times the amount of air was insufflated into the simulated stomach per
breath when the subjects used a bag valve device. “Aggressive bagging allows air to enter the patient’s
stomach by creating airway pressures that exceed the pressure of the lower esophageal sphincter. Once air
enters the stomach, it begins an adverse cycle in which it becomes more likely that air will continue to be
pumped into the stomach, causing further stomach insufflation, reduced pulmonary compliance, and decreased
lung ventilation. Gastric inflation can lead to regurgitation and aspiration.
The Hidden Cost of Bag Valve
Devices
In addition to the many safety concerns of bag valve devices, bagging
completely incapacitates a medical responder from addressing other injuries, performing compressions,
attending to other patients, or these features are often overly sophisticated and expensive for pre-hospital
use. EMS providers usually rely on 50 psi tanks that are secured in the ambulance. Consequently, the patient
is usually bagged from point of injury to the ambulance and then again when transported from the ambulance to
the emergency department. CPR Medical has developed an efficient, safe, and cost-effective alternative to bag
valve devices that provides the safety, ease of use, and level of respiratory support required in the
(pre)-hospital environment. Sending additional responders to the
scene to address the possible need for respiratory support is not a cost-effective or realistic use of
man-power. In mass casualty situations where responders have to triage the critically wounded, patients who
need to be bagged are likely to be left to die. Equipment that mitigates the potential for injury, reduces
operator error, complies with guidelines, and improves a medical responder’s ability to perform other
critical tasks is therefore critically needed.
The Merger of Ventilatory Capability
The majority of the EMS market relies on either bag valve devices.
Although bag valve devices are simple instruments, skill and vigilance are essential, and even then
consistent air delivery is not assured. It is rugged and highly portable. It is a set-flow, pressure-cycled
15 to 30 cm H2O device. The ventilator is completely self-contained, weighs only 180 gram. It is ideally
suited for situations where the size, weight, portability, and extreme ease of use are a consideration. The
small footprint (48 mm X 100mm) enables easy storage in a medical bag or on an ambulance. Field medics, mass
casualty incident coordinators, and EMS professionals will find the device well suited to their needs. Ideal
adjunct between bag valve devices and expensive transport ventilators. It is a hybrid of both ends of the
market. However, it is easier to use, more compact, and less expensive than most low-end pneumatically driven
models. The device can be used with either a mask or an airway. In a BLS setting, the device can be quickly
set up en out or on the scene with a mask so that ventilations can be given immediately. The flow rate (30
liters per minute) and pressures are designed to minimize gastric inflation. In mass casualty situations
where responders have to triage the critically wounded patients who need to be bagged are likely to be left
to die. Equipment that mitigates the potential for injury, reduces operator error complies, with guidelines
and improves a medical responder’s ability to perform other critical tasks is critically needed. Excessive
ventilation raises the mean intrathoracic pressure, which impedes venous return and decreases preload, stroke
volume and cardiac output.
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