Fig. 1. Local infiltration of 5–10 mL of mepivicainec ously at the planned site of trephination.
subcutane-
the general practice setting we have found IV ad- ministration of detomidine HCLa (0.01–0.02 mg/kg) and morphine sulfateb (0.2–0.4 mg/kg) to be simple and effective and is given once and then thereafter as needed to effect. We have found the trephina- tion site in the frontal sinus to be the most useful given that it allows direct access and visualization of the frontal, dorsal conchal, and caudal maxillary sinuses; and indirect access to the ventral conchal and rostral maxillary via fenestration of the ventral conchal bulla, more accurately termed the bulla of the septum sinuum maxillarium or maxillary septum bulla (MSB).4 The site for trephination of the frontal sinus has been described previously.5 Briefly, the trephine is centered 60% of the distance from midline to the medial canthus and 0.5 cm cau- dal to a line connecting both medial canthi. An area surrounding the trephination location is clipped and prepped in a routine manner. Al- though specific nerve blocks to provide local anes- thesia to the part of the skull to be entered have been described, we have found local infiltration of 5–10 mL of mepivicainec subcutaneously at the planned site of trephination to be effective and sim- ple (Fig. 1).6 A C-shaped incision is then made centered around the trephine hole with the base of the ‘C’ located axially (Fig. 2). A linear incision centered over the planned site of trephination is also acceptable. The incision is made to the underlying bone and the resulting flap, including the perios- teum, is dissected off the bone with a periosteal elevator or scalpel (Fig. 3). The trephine hole is then made, while protecting the flap, with either a handheld gault trephine or a sterile hole-saw and a portable drill, both of which are available at local hardware stores (Fig. 4). The diameter of the tre-
Fig. 2. A C-shaped incision is then made centered around the trephine hole with the base of the ‘C’ located axially.
Fig. 3. Following a skin incision to the level of the underlying bone and the resulting flap, including the periosteum, is dissected off the bone with a periosteal elevator or scalpel.
