Sellick maneuver revisited

Anesthetists the world over are obsessed with the fear of gastric regurgitation and pulmonary aspiration. Cricoid pressure is widely used to prevent this problem during induction of anesthesia and tracheal intubation, especially in emergency and full stomach situations. Much before the anesthetists realized the usefulness of this technique, vertical pressure applied on the cricoids cartilage was used by Dr. Monro during resuscitation of victims of drowning.[1] Thereafter in 1774, Dr. W. Cullen described this as "a means of preventing gastric distension during lung inflation."[1] Almost 200 years later the efficacy of the technique was described and popularized by Brian A. Sellick in 1961.[2] He provided radiological evidence that the cricoid pressure occludes the esophageal lumen at the level of 5th cervical vertebra. He further demonstrated that the cricoid pressure was effective in preventing gastric regurgitation. With the cricoid pressure in place, there was no run up of saline introduced in the esophagus from a height of 100 cm in a patient undergoing gastro-oesophagectomy.[3] "Sellick's maneuver" as the cricoid pressure came to be called, rapidly replaced the other means of preventing regurgitation and aspiration such as the use of awake intubation, inhaled induction and RSII with 40° head up tilt.[4] Some questions, however, remained unanswered - how much pressure, in which direction, and the best possible time to start applying the pressure. More evidence regarding its efficacy was also needed at that time to accept its universal usage. Later on, it was recommended that a pressure be applied directly backwards on the cricoid cartilage and to begin with it should be a "light pressure" of about 10 Newton while the patient is still awake. The same was to be gradually increased to about 30-40 Newton as the patient lost consciousness.[5] The efficacy of cricoid pressure was re-confirmed by Rice etal., who demonstrated that in human volunteers, application of cricoid pressure, irrespective of the direction of pressure, directly backwards or backwards and lateral, pushes both the cricoid and the hypopharynx immediately behind the cricoid, together as a unit, either against the vertebrae or against the longus colli muscles. In both situations the hypopharynx gets occluded.[6] The technique was soon modified and applied to situations, in which the glottis could not be visualized during direct laryngoscopy, and another name assigned to this technique - backwards, upwards and right pressure (BURP) applied on the thyroid cartilage. BURP maneuver too is popular to this date and a useful technique for tracheal intubation.[78] Despite wide spread acceptance and use, the efficacy and reliability of cricoid pressure were again questioned around the turn of the millennium. The main reasons being that some cases of regurgitation and aspiration were reported even with the cricoid pressure in place.[9] Reports of esophageal rupture, and nausea and vomiting associated with cricoid pressure further strengthened the case against the use of cricoid pressure.[10] The technique of cricoid pressure was indeed even blamed for some incidents of "inability to mask ventilate", failure of tracheal intubation and correct laryngeal mask airway placement.[1112] In the recent past many doubts have been raised for the validity of the efficacy of cricoid pressure, as reviews have shown that there is no evidence of reduced incidence of pulmonary aspiration of gastric contents after cricoid pressure.[131415] With no evidence that cricoid pressure prevents pulmonary aspiration, and reports of increased morbidity directly attributed to the use of cricoid pressure, is it logical to continue the use of cricoid pressure? Avoidance of positive pressure ventilation during apnea after injection of a muscle relaxant prior to tracheal intubation in patients with full stomach ensures there is no gastric distension with oxygen or anesthetic gases, minimizing the chances of regurgitation and resultant aspiration. A large number of anesthesiologists no longer use suxamethonium to facilitate tracheal intubation, thus avoiding the potential rise in intra-gastric pressure attributed to this muscle relaxant which could further increase the incidence of gastric aspiration. In my personal experience, a large number of my anesthesia colleagues are apprehensive about the correct application of cricoid pressure while it is being applied. It is not uncommon to manipulate the larynx while cricoid pressure is being applied and often incorrectly applied pressure makes intubation difficult. In this era of "evidence based medicine" and "protocols," it is high time the anesthetists gave a serious thought to the continued teaching and practice of this technique.