Resuscitator

In the early days of pre-hospital emergency services, pressure cycled devices like the Pulmotor were popular but yielded less than satisfactory results.

The mask covers the mouth and nose, and has a peripheral seal that fits most face shapes, and is generally held in place by the operator.

It is a small portable device used in the pre-hospital setting to provide emergency ventilation to a patient who is either in respiratory failure or cardiac arrest.

The pocket mask is designed to be placed over the lower face of the patient, creating a seal enclosing both the mouth and nose.

[citation needed] Modern pocket masks have either a built in one-way valve or a disposable filter to protect the operator responder from potentially infectious bodily fluids, such as vomit or blood.

In these early days, perhaps[weasel words] the most advanced piece of equipment carried on these ambulances were devices for delivering supplemental oxygen to patients in respiratory distress.

[citation needed] The Pulmotor and later models, such as the Emerson Resuscitator, used heavy cylinders of oxygen to power a device which forced air into the patient's lungs.

To ensure that the victim's lungs were not injured from being over-inflated, the resuscitator was pre-set to provide what was considered a safe pressure of oxygen.

[clarification needed] Pressure cycling also meant that cardiopulmonary resuscitation was impossible to perform if a patient's respiration was being supported by one of these units.

Due to the limitations imposed by the cycling feature, this meant that patients in need of rescue breathing benefited little from the application of these devices.

[clarification needed] The demand valve could also provide oxygen at any flow rate required to a conscious patient in respiratory distress.

Later medical opinion decided that getting high flow oxygen into a patient's airway was a factor in causing vomiting and aspiration.

Introduced in the 1960s by the Danish company Ambu, this device allowed two rescuers to perform CPR and ventilation on a non-breathing patient with an acceptable chance of success.