Head Positions to Open the Upper Airway

Ventilation during basic life support improves survival in cardiac arrest patients significantly. Unfortunately, this is in contrast to the willingness of potential rescuers to perform mouth-to-mouth ventilation. For example, although healthcare professionals would perform mouth-to-mouth ventilation on a 4-year old drowned child in >90% of cases, this likelihood would decrease to ~10% in the case of a young male unconscious patient in a San Francisco public bus. Possibly, lay rescuers would perform assisted ventilation more often if a simple ventilation device were available. However, both the willingness to perform assisted ventilation plus the ability to open and to maintain the airway patent are necessary to ensure efficient ventilation in an unconscious patient with an unprotected upper airway.

Since retention of skills after basic life support classes are notoriously low, a resuscitation tool should incorporate self-explanatory features to improve applicability, and to provide built-in safety. Thus, an option could be to ensure an open airway by the use of a built-in indicator within a ventilating device to confirm correct head extension. One possible approach may be to determine head position angles that make an open airway likely, and integrate these angles into a scale on a ventilating device; however, safe head extension needs to be determined first to prevent harm.

The purpose of this study is to determine head position angles and ventilation parameters reflecting neutral position, maximal extension and a position deemed optimal by an anaesthesiologist in patients undergoing anaesthesia induction for elective surgery in a first step to design a ventilating device to optimise ventilation of an unprotected upper airway. The investigators will ventilate 30 patients with a pillow under the head simulating ventilation in the operating theater, and 30 patients without a pillow under the head simulating ventilation during cardiopulmonary resuscitation.

Dentures will not be removed during assessment. After anaesthesia induction the head will be consecutively flexed in the three positions and measurements performed. Afterwards, general anaesthesia and surgery will ensue. The health risk for this extra minutes of mask ventilation is minimal.

The null hypothesis is that there will be no differences in head position angles and ventilation parameters.