Effect of a Shoulder Roll on the Glottic View in Infants

On the day of the surgery, healthy infants will be evaluated by an anesthesiologist for a preoperative clearance and suitability for inclusion in the study. If the infants are eligible, the parents will receive a detailed explanation of the study that is written into the consent form. Written consent will be obtained from those parents who are willing to enroll their children in the study. After consent, the concealed randomization code for the next subject in the study will be opened to determine the sequence of the positioning as described below.

The infants will be unpremedicated. In the operating room, anesthesia will be induced using a standard inhalational induction (that includes, 70 % nitrous oxide and 30 % oxygen followed by 8% sevoflurane). Upon the loss of eyelash reflex, ventilation will be assisted and intravascular (IV) access will be secured. Once IV access is established, Propofol, 3 mg/kg will be administered and the lungs ventilated with 8% sevoflurane in 100% oxygen for 1 minute. The randomization code will then determine the order of the laryngoscopy: either no shoulder roll or a 2 inch shoulder roll first, then the alternative position. For both positions, direct laryngoscopy using a #1 size straight Miller blade will expose the larynx to obtain the optimal glottic view. At this point, the distance from the lateral canthus of the eye of the anesthesiologist to the level of the table will be recorded (distance A) using a standard measure anchored on the operating room table top and a photo of the glottic opening will be taken using a high-quality digital hand-held camera. This photo will be referred to as photo 1. The shoulder roll will either be removed or inserted under the shoulders (based on the randomization) while the anesthesiologist holds the laryngoscopic view of the larynx. The anesthesiologist's head will then move (if necessary) up or down to establish the optimal view of the larynx again and the distance from the lateral canthus of the eye of the anesthesiologist to the table top will again be measured (distance B). A photo of the laryngoscopy view (photo 2) will be taken. The entire laryngoscopy will take less than 30 seconds. If the child desaturates to less than 93%, the study will be aborted and the lungs ventilated. An anesthesiologist, who is blind to the study hypothesis, will evaluate the photos of the glottis view the Percent of Glottic Opening scale (POGO) in 10% increments. The primary outcome will be the distance from the lateral canthus of the anesthesiologist's eye to the level of the table with and without a shoulder roll (distance A and distance B) will be compared using paired t-test. (P<0.05 will be accepted). The secondary outcome will be the glottic views (photos 1 and picture 2) compared using the Kruskall Wallis test.