Neuromuscular blockers (NMBs) are widely used in anaesthesia practice during endotracheal intubation. The degree of neuromuscular block is usually evaluated by clinical criteria. But the recommendation for application of neuromuscular monitoring to patients receiving NMBs is based on two important issues: first, on the variable individual response to muscle relaxants and second because of the narrow therapeutic window. Adequate muscle relaxation  for intubation corresponds to a narrow range of 90 to 95% receptor occupancy.¹ Inadequate muscle relaxation during intubation can lead to difficulty in securing the airway or multiple attempts leading to laryngeal morbidity like postoperative hoarseness (4-42%) and vocal cord injury.²

Rocuronium is one of the most commonly used non depolarising muscle relaxant for intubation of the trachea. It has been postulated that laryngeal muscles being resistant to the effects of neuromuscular blocking agents,³ require at least twice the ED95 dose.⁴

As it is difficult to quantify the relaxation of the laryngeal muscles, therefore surrogates such as Adductor pollicis longus (APL), orbicularis oculi (OO), corrugator supercilii (CS)⁵ and even flexor hallucis brevis (FHB)⁶ have been utilised, though APL is the preferred site. Neuromuscular transmission can be monitored by various methods like single twitch (ST), double burst stimulation (DBS) and train of four (TOF). Although good clinical research practice (GCRP) states that either ST or TOF can be used as a guide for intubation, TOF is preferable because it is more sensitive to lesser degree of receptor occupancy than single twitch.¹ Observation of evoked TOF responses after a dose of non depolarising  muscle relaxant allows prediction of onset time of paralysis of laryngeal muscles  in individual patients.

In the absence of availability of NMT monitors, timed intubation has been practiced. However, patient factors¹ such as age, gender,⁷ medical condition (ASA physical status), body weight affect the pharmacokinetics and pharmacodynamics of the drug. 

On reviewing the literature, we found that although, clinically acceptable conditions have been obtained with rocuronium 0.6mg/kg in 90 seconds, there have not been many studies to quantify the proportion of patients having excellent conditions and time required thereof for a standard observable endpoint i.e, disappearance of either three (T1) or all twitches (T0) after a TOF stimulus. The literature does not indicate which endpoint provides the best intubating conditions.

Therefore there is a need to ascertain the percentage of healthy routine patients achieving excellent intubating conditions and the time taken to achieve these with rocuronium 0.6mg/Kg using defined monitor i.e, TOF stimulation and associated post operative sore throat if any.