The effects of low-dose ephedrine on intubating conditions following low-dose priming with cisatracurium

Comparison of Effect of Ephedrine and Priming on the Onset Time of Vecuronium

Background:

Succinylcholine has been the neuromuscular blocking drug of choice for laryngoscopy and intubation, but it has several adverse effects. Nondepolarizing neuromuscular blocking drugs are good alternative provided their onset of action is hastened. Priming technique and use of ephedrine or MgSO₄ pretreatment is good options.

Aims:

To compare the effects of priming and ephedrine pretreatment on the onset time of intubating dose of vecuronium.

Settings and Design:

A prospective, randomized comparative study was done at a state-owned tertiary care teaching hospital.

Materials and Methods:

After obtaining the Institutional Ethical Committee approval and written informed consent, sixty patients of either gender aged 18–60 years, the American Society of Anesthesiologists physical status Class I/II, weighing 40–70 kg, were randomly divided into two groups of thirty each. Group E received 70 μg/kg ephedrine, and Group P received 0.01 mg/kg of vecuronium 3 min before intubating dose of vecuronium. Intubation was done after getting a train of four zero. Intubation time, clinical intubation grade using Cooper's scale, and hemodynamic parameters were noted.

Statistical Analysis Used:

Chi-square test and independent t-test were done with PASW statistics 18 to analyze data.

Results:

The mean time for intubation in ephedrine group (E) was 104 ± 23.282 s and in the priming group (P), it was 142 ± 55.671 s (P = 0.001). All patients had clinically acceptable intubating conditions, and the grades were comparable among groups (P = 0.791). Hemodynamic parameters were comparable between groups at all time frames (P > 0.05).

Conclusion:

Pretreatment with ephedrine 70 μg/kg shortens the onset time of vecuronium for intubation and is superior to the priming technique. Low-dose ephedrine, when used along with propofol induction, provides hemodynamic stability during induction and intubation.

Comparison of etomidate and propofol on intubating conditions and the onset time associated with cisatracurium administration

Background

This study compared intubating conditions and the onset time associated with administration of cisatracurium, a nondepolarizing neuromuscular blocker with a relatively slow onset, according to prior injection of one of two intravenous anesthetic agents: propofol or etomidate.

Methods

Forty-six female patients, undergoing general anesthesia and endotracheal intubation for elective surgery, were randomized to two groups; group P were administered propofol (2 mg/kg) prior to cisatracurium (0.2 mg/kg); group E were administered etomidate (0.3 mg/kg) prior to cisatracurium (0.2 mg/kg). We measured intubating conditions and the onset time according to the types of intravenous anesthetic administered. Measurements of heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP) were taken immediately prior to induction; immediately and 1 min after IV anesthetic administration; and immediately and 1, 2, 3, 4, 5, 7, and 15 min after endotracheal intubation.

Results

Intubating conditions were superior in group E compared with group P (P = 0.009). The average onset time of cisatracurium was more rapid in group E (155.74 ± 32.92 s vs. 185.26 ± 38.57 s in group P; P = 0.008). There were no group differences in SBP, DBP, and HR following intravenous anesthetic drug injection and endotracheal intubation. However, SBP and DBP were substantially higher in group E after endotracheal intubation.

Conclusions

Etomidate improves intubating conditions and provide a more rapid onset time of cisatracurium during anesthetic induction compared to propofol.

The dose effect of ephedrine on the onset time and intubating conditions after cisatracurium administration

Background

The aim of this randomized, double-blind, placebo-controlled study was to evaluate dose effects of ephedrine pretreatment on the onset time and intubating conditions after cisatracurium administration.

Methods

A total of 140 adult patients were randomized into 4 groups to receive either 30 µg/kg ephedrine (Group 30, n = 35), 70 µg/kg ephedrine (Group 70, n = 35), 110 µg/kg ephedrine (Group 110, n = 35), 3 ml normal saline (Group C, n = 35) as pretreatment given 30 s before anesthetic induction. Neuromuscular block was achieved with 0.15 mg/kg cisatracurium, evaluated accelomyographically with train-of-four stimulation. An anesthesiologist blinded to patient grouping assessed the intubating conditions 1.5 min after cisatracurium administration.

Results

An onset time of 70 s was obtained in the ephedrine groups (Group 30: 155.4 ± 44.7 s, Group 70: 152.6 ± 40.3 s, Group 110: 151.2 ± 51.6 s) compared to Group C (224.6 ± 56.9 s) after 0.15 mg/kg of cisatracurium (P < 0.001). Ephedrine doses of either 70 or 110 µg/kg for pretreatment significantly improved intubating conditions (P < 0.05). Systolic and diastolic blood pressure and heart rate at 1 min after tracheal intubation were significantly increased than other times in all groups (P < 0.001), with no differences among the groups. However, 5 patients in Group 110 experienced marked hypertension (systolic/diastolic blood pressure: > 200/100 mmHg) 1 min after tracheal intubation with no patients in other groups.

Conclusions

We conclude that pre-treatment with ephedrine 70 µg/kg improved intubating conditions 1.5 min after cisatracurium administration and facilitated the onset of neuromuscular block (70 s) without adverse hemodynamic effects.

The effect of low dose ketamine and priming of cisatracurium on the intubating condition and onset time of cisatracurium

Background

Both ketamine and priming may accelerate the onset time of neuromuscular blocking agents. We investigate the effect of low dose ketamine and cisatracurium priming on the intubating condition and onset time of cisatracurium.

Methods

After Institutional Review Board approval, 120 consecutive patients undergoing general anesthesia were randomly assigned to one of 4 groups. All patients were injected one of normal saline (group C), cisatracurium 0.01 mg/kg (group P), ketamine 0.5 mg/kg (group K) and combination of cisatracurium 0.01 mg/kg, and ketamine 0.5 mg/kg (group PK) diluted into a 5 ml solution, followed 3 minutes later by cisatracurium 0.15 mg/kg in group C and K, and 0.14 mg/kg cisatracurium in priming group. Onset time was recorded the electromyographical responses using single twitch and intubating conditions were evaluated at 60 seconds after cisatracurium administration.

Results

The mean onset time was most significantly accelerated in Group PK and was also significantly more accelerated in Group P and K compared with Group C (P < 0.008). It was 112.7 ± 13.2, 91.4 ± 17.9, 84.9 ± 12.7 and 76.4 ± 8.3 seconds in Group C, P, K, and PK, respectively. Intubating conditions were significantly improved in Group P, K and PK than Group C (P < 0.008). Especially, Group PK showed most significant improvement of intubating conditions.

Conclusions

The combination of the low dose ketamine and cisatracurium priming accelerated the onset time and was improved the intubating conditions.

A randomised controlled trial comparing rocuronium priming, magnesium pre-treatment and a combination of the two methods

We investigated whether magnesium sulphate combined with rocuronium priming shortens the onset of neuromuscular blockade, compared with these methods used alone. Ninety-two patients scheduled for general anaesthesia were randomly allocated to one of four groups: controls were given 0.6 mg.kg(-1) rocuronium; patients in the prime group were given 0.06 mg.kg(-1) rocuronium three minutes before a further dose of 0.54 mg.kg(-1) rocuronium; patients in the magnesium group were given an infusion of 50 mg.kg(-1) magnesium sulphate before rocuronium and patients in the magnesium and prime group were given both the magnesium sulphate and the priming dose of rocuronium. Tracheal intubation was attempted 40 s after the rocuronium injection. The time to onset of neuromuscular blockade was the primary outcome; duration of blockade and tracheal intubating conditions were also measured. The group allocation and study drugs were coded and concealed until statistical analyses were completed. The magnesium and prime group had the shortest mean (SD) onset time (55 (16)s; p < 0.001), and best tracheal intubating conditions (p < 0.05). No statistical difference was found for the duration of blockade. As for adverse events, a burning or heat sensation was reported in eight (35%) and six (26%) patients in the magnesium and magnesium and prime groups, respectively. The combination of magnesium sulphate and rocuronium priming accelerated the onset or neuromuscular blockade and improved rapid-sequence intubating conditions, compared with either magnesium sulphate or priming used alone.