Electrically Guided Needle Insertion: ICU Study

Background: Critically ill patients occasionally require a tracheostomy tube to breathe. A percutaneous tracheostomy can be performed, where a needle/catheter is inserted into the trachea, followed by insertion of a guidewire and a tube that dilates the tissue, creating a hole for the tracheostomy tube. Although this is a common procedure, it does pose risks to the patient, including accidental puncture of nearby structures. We wish to test a device that alerts the doctor to when the needle tip is in the tracheal lumen. The device has been proven to aid needle insertion in cadavers, but it needs to be tested on live patients. Since many intensive care patients undergo PT, we wish to test our technique on this population.

Study objective: To evaluate the effectiveness of a nerve stimulator in aiding needle tracheostomy in live patients.

Hypothesis: Nerve stimulation equipment will help the physician guide and insert the needle tip into the tracheal lumen faster and with more accuracy than conventional techniques.

Primary outcome: speed and accuracy of needle tip placement in the trachea.

Procedure: This study will involve recruiting consenting adult patients from the University of Alberta Hospital General Systems Intensive Care Unit (ICU) who require percutaneous tracheostomy to insert a tracheal tube. In this population, a tracheostomy is usually performed as a means to provide long-term assisted ventilation without the need for endotracheal intubation. Briefly, the patient is sedated, the skin on their neck disinfected, and a local anesthetic injected into the anterior neck. A bronchoscope is inserted down the endotracheal tube to aid in visualization and localization of needle puncture. The cricothyroid membrane is located by palpating the anterior neck and an incision is made over the membrane. A small needle is inserted through the membrane to act as a guide for a larger needle-catheter assembly. Both needles are removed and a guidewire is inserted through the catheter. Using forceps, the insertion site is widened and a tube to dilate the opening is inserted. The tracheostomy tube is then inserted and the dilation tube and guidewire are removed. The endotracheal tube is removed and the ventilation apparatus is connected to the tracheostomy tube.

We will supply ICU physicians with a commonly used nerve stimulator (Stimuplex HNS 12, B.Braun, Germany) to attach to the needle-catheter assembly used to make the first insertion into the trachea. The nerve stimulator will be connected to a current meter, and a ground electrode will be attached to the body. When the needle tip is in contact with body tissue (i.e., tracheal wall), the electrical circuit will be closed, producing a reading of 1.0 mA on the current reader. Suspension of the needle tip in the airway will interrupt the circuit, producing a reading of 0.0 mA. In addition, an audible signal built into the nerve stimulator will alert the user to a change in current, warning that the needle tip has advanced too far and is in contact with the posterior or lateral tracheal wall.

The physician will perform percutaneous tracheostomy on 20 ICU patients that require endotracheal extubation and insertion of a tracheostomy tube. This will help support our preliminary observations which showed that the nerve stimulator was helpful in guiding needle insertion using human cadavers. By showing that the technique is equally as effective when used on live patients, we can argue that a nerve stimulator or similar device can ensure accurate, quick, and safe needle insertion when accessing the airway percutaneously.

Inclusion criteria: Adult; requires tracheostomy

Exclusion criteria: Failure to provide consent; known upper airway pathologies; known oro-pharyngeal or laryngeal disease, including any swelling, tumour, or infection; previous radiotherapy or operations on the neck; cervical spine fractures.