Use of Tragus Pressure in Guiding Emergence From Anaesthesia

More than 70% of general anaesthesia are now performed with laryngeal mask (LMA) as the airway support device with state of the art intra-operative monitoring such as end tidal inhalational anaesthetic agent concentration and fronto-temporal electroencephalographic waves analysis such as the Bispectral index score (BIS) and entropy. The use of LMAs have promised rapid turnover allowing more patients to be operated in the limited operating theatres' time. This comes with the additional price of losing the continuity of advanced monitoring devices in the post anaesthesia units, the best being end tidal carbon dioxide analysis. When patients are brought to the PACU, much of the monitoring of emergence from anaesthesia is fairly done through clinical measures such as motor activity, response to auditory stimuli, tactile taps on shoulder and occasional nociceptive stimuli such as sternal rub. The timing of the responsiveness of these stimuli is unknown and nursing support teams are unable to suggest a frame of time on when the patient would recover. One of the main reasons for this unpredictability is that the recovery is not planned based on the last recorded end tidal anaesthetic agent concentration before leaving the operating theatre to be shifted to PACU, but by an approximation of time since the patient has arrived in PACU and by early signs of recovery such as appearance of forehead wrinkles or motor activities. The incidence of airway events such as laryngospasm, obstruction after removal of airway devices, desaturations from resedation/ apnea and rescue measures such as reintubation/ ambu ventilation needed globally and from our local data is up to 1-5%. The incidence is higher with children and patients with reactive airways, obesity and associated complicating comorbidities. Using BIS monitoring and end tidal agent analysis for each of the 18 post anaesthesia care unit bays for recovering patients scientifically is not a cost-effective initiative. The tragus pressure technique has been known to be appropriate stimuli that has adequate stimulation of reticular activating system (RAS) without producing nociception that can trigger airway events such a laryngospasm. Physiological sleep studies have quoted that tragus pressure can contribute to arousal without causing vagotonic response that is known to occur from 'startle response' or sudden emergence. Through this study we propose to evaluate the consistency in predictability of recovery from general anaesthesia and deep sedation with Ramsay score 3 through application of tragus pressure. The presence of reflex pupillary dilatation and early signs of recovery such as swallowing, gentle grimace and minor peripheral motor movements, we propose, gives a predictable plane of recovery from anaesthesia where the LMAs are removed safely without treading the dreaded stage 2 of excitability of anaesthesia. The proposed method also allows for continued responsiveness of patient with coherent verbal responses to auditory stimuli after safe removal of the airway, thereby minimizing the incidence of airway complication and hence the interventions required for the same. The continued alert responsiveness of the patient also allows for the post anaesthesia unit team to attend to other patients who might need more immediate care.

Inclusion criteria

• ASA 1 and 2
• Surgeries with no risk of aspiration
• Patients with laryngeal mask airway (LMA) insitu on arrival in the PACU
• Surgery duration < 4 hours

Exclusion criteria

• ASA 3 and 4
• Organ failure with decompensation : Eg Heart failure, renal failure, liver failure
• History of psychiatric illness or medications for mood control
• Pregnancy
• Patients for neurosurgery or GCS <12/15
• LMA used for failed intubation or difficult airway protocol
• Patients with no LMA on arrival in the PACU
• Patients who are awake with LMA/ Responding to call on arrival at PACU