Ergonomic face mask

Details Ergonomic face mask Ergonomic face mask

2002-03-12

2003-11-25

Dawson, Glenn K. (Department: 3761)

Surgery

Respiratory method or device

Means for supplying respiratory gas under positive pressure

C128S205130, C128S206210, C128S206220, C128S206230, C128S206240, C128S206250, C128S206260, C128S206270, C128S206280, C128S206290

Reexamination Certificate

active

06651661

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a face mask of the type used in airway management in the anesthesiology, critical care, emergency medicine and resuscitation fields, and in particular relates to an ergonomically shaped face mask (EFM) with increased comfort and adherence to the operator's hand.
2. Description of the Related Art
The symmetrical face mask dome was first developed in the middle of the 19th century, and was designed for spontaneously breathing patients. The first face mask was designed for anesthetic purposes, whereby anesthetic gasses were administered passively through the face mask to spontaneously breathing patients in a sitting position. While the dome was sufficient for that purpose, its symmetrical nature presents challenges when providing positive pressure ventilation to a patient who isn't breathing, especially when the operator has only one hand available for the mask.
The face mask used in anesthesia, emergency medicine, critical care and resuscitation is a device through which oxygen or anesthetic gasses are administered under positive pressure to a patient. Positive pressure mask ventilation allows the forceful, active administration of oxygen and/or anesthetic gasses from a source to a non-breathing patient. Typically, the attending physician or rescuer (hereinafter collectively referred to as the operator) uses a bag-mask device and holds the face mask with the left hand and squeezes the bag (develop positive pressure air flow) with the right hand.
Several factors contribute to the success of positive pressure mask ventilation. For example, the patient's facial bone structure affects the quality of the seal between the mask and the face, it being appreciated that an unlimited variety of facial sizes and shapes exist. Accordingly, it is desirable to provide a mask that is capable of forming a reliable seal with several facial structures.
Thus, the specific design characteristics of the face mask also contribute to the success of the mask ventilation. Referring to
FIG. 1
, a conventional symmetrical face mask
10
is illustrated of the type used by anesthesiologists, paramedics, EMS personal, firefighters, ER personal and anybody involved in artificial ventilation. The two primary components of the face mask
10
include a cuff
11
at its base, and a symmetrical dome
22
extending upwardly from the cuff. The cuff
11
makes direct contact with the face of the patient during ventilation. The dome
22
is used by the operator to grip and seal the mask to the patient's face, and typically has a (left-right) symmetrical appearance. The dome
22
has a connector
20
for administering the gas from the source to the patient.
Thus, the ventilation technique also contributes to the success of positive pressure mask ventilation. While bag-mask ventilation is a complex technique that requires considerable skill and practice, the complexity is further increased when attempting to provide performing ventilation using one hand. A good face-mask seal is achieved by applying and corroborating two simultaneous forces. In particular, an upper pressure is applied on the dome and a lower pressure is applied to the patient's jaw. The upper forces are developed as the hand holds the mask with the thumb and index finger around the connector.
Three asymmetrical pressure areas are developed on the dome by the first and second fingers and the palm. The contact area of an operator's left hand on the mask
10
is identified generally by hatching
18
. The tip of the index finger applies pressure to the right side of the dome at location
14
, and the palm applies pressure to the left side of the dome at location
16
. These pressure areas are connected as the left palm makes full contact with the dome (FIG.
1
). The thumb engages the right side of the dome at location
12
. The lower pressure forces are developed by the middle, ring, and small fingers as they pull the patient's jaw and the face mask together. The airway of a patient may be opened by applying a “jaw thrust” maneuver, which is especially critical when the patient is unconscious and the tongue obstructs the airway. If the jaw thrust maneuver is unsuccessful, the ventilation will fail regardless of the quality of seal between the mask and the patient's face.
The application of symmetrical pressure on the face mask is much more difficult when only one hand is used to position the face mask and maintain an open airway while the other hand is being used to squeeze the bag. In the example illustrated, the thumb and the tip of the index finger applies the majority of the pressure on the right side of the mask
10
, while the palm and remaining fingers apply pressure to the left side of the mask. With the hand gripping the mask
10
in this position, it is apparent that a user would naturally apply asymmetrical forces to the symmetrical mask. Considering the asymmetrical forces necessary to be applied with the left hand on a symmetrical face mask, the seal is usually lost on the right side of the mask.
When using conventional face masks with one hand, the operator's hand position is therefore required to be substantially horizontal, with the wrist and forearm twisted out of their natural and relaxed position. In order to generate a sufficient grip in this position, the fingers are forced to assume a “claw-like” posture. This non-neutral position is uncomfortable, tiring, and painful especially when increased force is necessary to obtain and maintain a seal. The user also may need to change his/her grip several times, and may become fatigued, especially with sub-optimal results in ventilation. This can lead to poor oxygenation of the patient and pollution of the operating room with anesthetic gasses. Furthermore, the grip is typically realized between two smooth surfaces, in particular a gloved hand and the symmetrical dome. The situation becomes critical when secretions and blood make the smooth surfaces slippery due to face trauma, vomitus, excessive secretions, and the like.
Due to the difficulties associated with delivering positive pressure mask ventilation with one hand, the Basic Life Support (BLS) for Health Care Providers and the Guidelines 2000 for Cardiopulmonary Resuscitation- CPR and Emergency Cardiovascular Care recommend the two-rescuer use of the bag-mask. In particular, one operator is designated to properly position and hold the mask on the patient's face with two hands, while the other operator is responsible for squeezing the bag. Two hands may therefore be used in applying symmetrical pressures on the symmetrical face mask to ensure an adequate seal. However, this technique is only useful when two trained rescuers are available to manage the ventilation of the patient. In an overwhelming number of cases, however, one rescuer is forced to perform one-hand ventilation.
Improvements to positive pressure ventilation are only partially addressed by prior art. The majority of improvements made to the face mask were primarily aimed at improving the patient's comfort. As a result, face masks were produced having an inflatable and ergonomically shaped cuff that better conform to facial features, such as the chin curve. The quality of the seal between the face mask and the patient's face was still dependent upon a correct ventilation technique with the mask. The prior art fails to address the ergonomic aspect of hand-mask interaction.
For example, European patent application 0427474A2, published May 15, 1991 and entitled “Face masks and face masks components” describes a face mask and face mask components used in ventilation. In particular, a water-activated hydrophilic polyurethane foam provides a cushion to minimize discomfort to the wearer. EP 0427474 A2 acknowledges that, while face plates typically found in conventional face masks are smooth to minimize discomfort to the wearer

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