Ultrasound is Superior to Conventional Palpation Method in Identification of the Cricothyroid Membrane in Subjects With Poorly Defined Neck Landmarks: A Randomized Clinical Trial

Inability to secure the airway remains the most frequent cause of anesthesia-related mishaps.Difficult airway management continues to be the major challenge in anesthesia as it is responsible for a third of anesthesia-related claims and is the single largest class of closed claim injury suits. Difficulties in tracheal intubation is the most frequent cause of anesthesia-related morbidity and mortality.

Repeated attempts of tracheal intubations can result in serious soft tissue injury and rapidly deteriorate into a life threatening "cannot intubate-cannot ventilate" (CICV) crisis. The guidelines suggested by the American Society of Anesthesiologists and the Difficult Airway Society for managing the unanticipated difficult airway recommend the performance of a cricothyrotomy(CTY) as the next step for a CICV scenario.

Cricothyrotomy is an infrequently performed life saving procedure when facing a difficult CICV airway.Previous studies quote, the incidence of the CICV scenario to be in the range of 0.01-2 per 10,000 cases. It is therefore imperative that anesthesiologists have the necessary knowledge and skills in successfully managing this life-threatening airway crisis. However, several studies demonstrated that many practicing anesthesiologists and anesthesia trainees (residents/fellows) are uncomfortable with the management of a CICV situation because it is such a rare event. A recent Canadian survey shows that only a quarter of the residents and 40% of practicing anesthesiologists were comfortable with performing a cricothyrotomy. Similar findings were reported in a German national survey of academic teaching hospitals where difficult airway situations, particularly a CICV crisis, were poorly managed and were postulated to have contributed to adverse patient outcomes.Complications of emergency CTY by physicians are common, with rates ranging from 9% to 40%.These complications include failure to cannulate the trachea, false airway passage, severe bleeding, posterior tracheal wall injuries, pneumothorax and esophageal laceration. All of these major complications may be related to improper identification of anatomical landmarks used to identify the correct position of cricothyroid membrane (CTM). The current method of CTY relies solely on digital palpation of these landmarks to accurately identify the CTM.

Several studies have identified independent predictors for patients with difficult airway. These include characteristics such as high body mass index, presence of beard, short bull neck, distorted neck anatomy either due to congenital or acquired pathology such as goiters or radiation to the neck. These are the same factors which may lead to improper identification of neck landmarks for the CTY.

The outcome and accuracy of CTY may be improved with better preparedness and pre-procedural identification of the neck landmarks for CTY before deciding the method of anesthetic. This is especially true in patients with anatomical features of difficult airway, who may be the ones more likely to have a difficult airway or require an emergency CT. In this patient population, incorrect localization of the CTM may lead to significant airway morbidity or failure to quickly establish an airway.