Instruments Used in ENT

The DOHNS instrument station most commonly tests: the Thudichum nasal speculum, Gruber or Hartmann aural speculum, Boyle-Davis gag with Doughty blade, Draffin rods, Jobson Horne probe, Tilley nasal dressing forceps, Negus knot pusher, Denis Browne tonsil holding forceps, Gwynne Evans dissector, Trousseau tracheal dilating forceps, bipolar diathermy forceps, and Merocel nasal pack. For each you should be able to state: the full correct name, what it is used for, and any specific practical point (e.g., "You should never cauterise both sides of the nasal septum with silver nitrate at the same sitting").

Applying silver nitrate to the same area of the nasal septum on both sides simultaneously creates opposing areas of ischaemic necrosis. Without healthy mucosa on either side to support the cartilage, the underlying septal cartilage can become avascular and necrotic, leading to a septal perforation. Therefore, if cauterisation is needed bilaterally, it should be performed on one side first and the other side treated no earlier than 4–6 weeks later, once the first side has fully healed.

Post-thyroidectomy neck haematoma is a rare but life-threatening emergency. Blood accumulates in the enclosed neck compartment, compressing the trachea and causing rapidly progressive airway obstruction. If the patient deteriorates acutely with stridor or respiratory distress, the neck wound must be opened immediately at the bedside — before transfer to theatre — to decompress the haematoma. In wounds closed with staples, the staple remover is the fastest instrument with which to open the wound. A scalpel is an acceptable alternative. The priority is immediate decompression of the haematoma, not a controlled return to theatre.

In monopolar diathermy, the electrical current flows from the active electrode (the diathermy pen or tip) through the patient's body to a grounding pad placed on the skin — the current path through the patient is broad and thermal effects can spread unpredictably. In bipolar diathermy, the current passes only between the two tips of the forceps — the path is confined to the tissue between the tips, making it much safer near vital structures (facial nerve, recurrent laryngeal nerve). In ENT, monopolar is used for skin incisions, broad tissue coagulation, and adenoidectomy (where precision is less critical). Bipolar is preferred for tonsillectomy, middle ear surgery, parotidectomy near the facial nerve, and thyroidectomy near the recurrent laryngeal nerve.

Merocel is made from compressed polyvinyl acetate foam. In its dry state it is firm and compact. When moistened with blood or saline it expands significantly — approximately threefold — to fill the nasal cavity. This expansion exerts radial pressure against the nasal walls and anterior septum, tamponading bleeding points. To insert it correctly: lubricate the pack thoroughly with antibiotic ointment or lubricating gel to ease passage; introduce it along the floor of the nose (not upward, which risks entering the skull base); push it fully to the posterior end of the nasal cavity in a single smooth movement; then apply saline to begin expansion. On removal (typically after 24–48 hours), moisten well with saline first to reduce adhesion before withdrawing.

The Boyle-Davis gag is a self-retaining mouth gag used to keep the mouth open under general anaesthesia during tonsillectomy and adenoidectomy. The cross-bar rests on the lower teeth (or gums in edentulous patients — use gauze padding). A Doughty tongue blade of appropriate size is clipped onto the frame to depress the tongue. The ratchet is adjusted to achieve the desired mouth opening. The whole assembly is then suspended on Draffin bipod rods placed either side of the patient's neck, propping the gag against the patient's chest — this holds it in place and frees both of the surgeon's hands for operating. The endotracheal tube runs between the cross-bar and the tongue blade in the midline.

A standard ENT tonsil pack should contain: a Boyle-Davis gag (with guard and ratchet), a Doughty tongue blade of appropriate size, Draffin bipod rods (usually two pairs), Denis Browne tonsil holding forceps, Gwynne Evans dissectors, a Mollison pillar retractor, bipolar diathermy forceps, straight Birkett artery forceps, curved Negus tonsil artery forceps, a Negus knot pusher, a Yankauer sucker, and curved scissors. For cold steel tonsillectomy an Eve tonsil snare may also be included. Additional items include gauge swabs, silk ties or vicryl ligatures, and a headlight or operating microscope.

Trousseau tracheal dilating forceps are used to dilate the tracheostomy stoma during tube changes, particularly in a fresh (immature) tracheostomy in the first 5–7 days post-operatively when the tract has not yet epithelialised. They are introduced into the stoma in the closed position and then opened to widen the stoma enough to introduce the new tube. They should be kept at the bedside of every patient with a tracheostomy — along with a spare tracheostomy tube of the same size and one size smaller — because accidental decannulation in a fresh tracheostomy is an emergency. Without the dilators, a fresh stoma can close within minutes, preventing tube reinsertion and causing asphyxia.