A Study of Priming Technique of Rocuronium in Facilitating Intubation

Abstract

Tracheal intubation is usually performed after induction of anaesthesia followed by relaxation of skeletal muscle with depolarizing or nondepolarizing Neuro Muscuc c lar Block Agent (NMBA). The ability to intubate the trachea rapidly and safely is still paramount in all clinical situations. Suxamethonium is still the drug of choice for this purpose. This short-acting depolarizing NMBA is probably the most popular drug used for making intubation quick, easy and atraumatic. But this drug has many side effects like post operative muscle pain, hyperkalemia, malignant hyperthermia, masseter rigidity etc. For these reasons, researchers have concentrated to develop an alternative drug to suxamethonium or an alternative method of using non-depolarizing NMBA (Neuromuscular Blocking Agent) for rapid sequence induction to intubation technique. Rocuronium bromide, an aminosteroid nondepolarizing NMBA, the onset time of which is significantly shorter than equivalent doses of other non-depolarizing NMBA .Priming technique with rocuronium has been investigated by several authors in an attempt to reduce the onset time and also to optimize it's efficacy and reduce the incidence of side-effects. This study was performed to investigate the influence of priming technique on the intubating time and intubation conditions with standard intubating dose of rocuronium (0.6 mg/kg), which may be comparable with standard intubation dose of suxamethonium (1.5 mg/kg). Thus using priming technique Rocuronium with standard intubating dose (0.6 mg/kg) may be suitable alternative to suxamethonium for rapid sequence induction of anaesthesia. So, we can avoid many life-threatening side-effects associated with suxamethonium like, hyperkalemia, massater spasm, malignant hyperthermia and we can also avoid mega-dose of rocuronium (0.9-1.2 mg/kg) used for same purpose. A total number of 90 adult subjects, aged 18-45 yr, ASA I-II, undergoing elective surgery were studied. The selected patients were equally divided into three groups, 30 patients in each group.Following induction with thiopentone (5mg/kg) and Fentanyl (2?gm/kg), patients in group-I (n=30) received suxamethonium 1.5 mg/kg, group-II (n=30) received a priming dose of rocuronium 0.06 mg/ kg followed 3 minutes later by an intubating dose of 0.54 mg/kg and group-III (n=30) received rocuronium 0.6 mg/kg in single bolus injection. Neuromuscular function was assessed at the wrist using acceleration transducer (TOF-watch). In priming group any unpleasant symptoms during priming like visual disturbance, feeling of dyspnoea, difficulty in controlling tongue were closely observed. Intubating conditions were assessed using the intubation criteria of Cooper et al. as excellent, good, fair or poor, based on jaw relaxation, position of the vocal cords and response of the diaphragm to intubation. The main outcome variables were intubating time and intubating conditions.Timing at intubation showed that all of the patients of suxamethonium group (group-I), 86.7% of the priming group (group-II) and nearly three quarter (73.3%) of the single dose rocuronium group (group-III) were feasible to be intubated within 60 second. The difference between the priming and the single dose rocuronium group was not statistically significant in terms of timing of intubation (p = 0.329). While evaluating intubating conditions, no significant difference was also observed between priming group (group-II) and single dose rocuronium group (group-III) in jaw relaxation (p=0.698), vocal cords movement (p=0.646) and response to intubation (p=0.514).The suxamethonium group allowed much earlier intubation compared to other two groups (p = 0.039) and in terms of intubating conditions, smooth intubation was significantly higher in suxamethonium group (Group-I) compared to other two groups (p = 0.043). In terms of unpleasant effects of priming it was observed that 1.1% of the patients of priming group had visual disturbances, 3.3% dyspnoea, 1.1% difficulty in controlling tongue and 2.2% difficulty in swallowing during the priming interval and remaining 92.7% was free of any unwanted sideeffects. Haemodynamic state at intubation and just after intubation demonstrateds that the haemodynamic variables like pulse rate, systolic blood pressure, diastolic blood pressure, oxygen saturation (SpO2) all were within physiological range and almost homogeneously distributed among the three groups and no adverse outcome was noticed. Using priming technique with standard intubating dose of rocuronium 0.6 mg/kg has no beneficial effects on reducing intubation time and providing better intubating conditions over single bolus injection of rocuronium 0.6 mg/kg .So Rocuronium 0.6 mg/kg in single bolus injection can replace suxamethonium for quick endotracheal intubation in surgical procedures of short and medium duration. Journal of BSA, Vol. 21, No. 1, January 2008 3-11