Probability of acceptable intubation conditions with low dose rocuronium during light sevoflurane anaesthesia in children

Neuromuscular-blocking agents for tracheal intubation in pediatric patients (0-12 years): A systematic review and meta-analysis

BACKGROUND

The benefit of using neuromuscular-blocking agents to facilitate tracheal intubation in pediatric patients remains unclear due to variations in design, treatments, and results among trials. By combining the available evidence, we aimed to establish whether scientific findings are consistent and can be generalized across various populations, settings, and treatments.

METHODS

A systematic search for randomized controlled trials, related to the use of neuromuscular-blocking agents for tracheal intubation in American Society of Anesthesiologists class I-II participants (0-12 years), was performed. We considered all randomized controlled trials that studied whether intubation conditions and hemodynamics obtained by using neuromuscular-blocking agents were equivalent to those that were achieved without neuromuscular-blocking agents. We combined the outcomes in Review Manager 5.3 (RevMan, The Cochrane Collaboration) by pairwise random-effects meta-analysis using a risk ratio (RR) for intubation conditions and mean difference for hemodynamic values (mean [95% Confidence Intervals]). Heterogeneity among trials was explored using sensitivity analyses.

RESULTS

We identified 22 eligible randomized controlled trials with 1651 participants. Overall, the use of a neuromuscular-blocking agent was associated with a clinically important increase in the likelihood of both excellent (RR = 1.41 [1.19-1.68], I²  = 76%) and acceptable (RR = 1.13 [1.07-1.19], I²  = 68%) intubating conditions. There is strong evidence that both unacceptable intubation conditions (RR = 0.35 [0.22-0.46], I²  = 23%) and failed first intubation attempts (RR = 0.25 [0.14-0.42], I²  = 0%) were less likely to occur when a neuromuscular-blocking agent was used compared with when it was not. Higher systolic or mean arterial pressures (mean difference = 13.3 [9.1-17.5] mm Hg, I²  = 69%) and heart rates (mean difference = 15.9 [11.0-20.8] beats/min, I²  = 75%) as well as a lower incidence of arrhythmias were observed when tracheal intubation was facilitated by neuromuscular-blocking agents.

CONCLUSION

The use of a neuromuscular-blocking agent during light-to-moderate depth of anesthesia can improve the quality as well as the success rate of tracheal intubation and is associated with better hemodynamic stability during induction of anesthesia.

Subparalyzing Doses of Rocuronium Reduce Muscular Endurance without Detectable Effect on Single Twitch Height in Awake Subjects

PURPOSE

To test the hypothesis that a low-dose rocuronium acts mainly by means of reducing muscular endurance rather than by reducing momentary force.

METHODS

In a randomized placebo-controlled double-blinded study, eight healthy volunteers were studied in two sets of experiments. In the first set, the subjects made a sustained maximum effort with the dominant hand for 80 seconds while squeezing an electronic handgrip dynamometer at three minutes after intravenous administration of placebo, 0.04 or 0.08 mg/kg rocuronium. Handgrip force at initiation of testing (maximum handgrip force) and after 60 seconds was evaluated. In the second set, the ulnar nerve of the subjects was electrically stimulated every tenth second for at least 10 and a maximum of 30 minutes following the administration of placebo and 0.08 mg/kg rocuronium. Single twitch height of the adductor pollicis muscle was recorded.

RESULTS

There was no significant difference in the effect on maximum handgrip force at time 0 between the three different doses of rocuronium. As compared with placebo, handgrip force after 0.08 mg/kg rocuronium was reduced to approximately a third at 60 seconds (214 N (120-278) vs. 69 (30-166); p=0.008), whereas only a slight reduction was seen after 0.04 mg/kg (187 (124-256); p=0.016). Based on these results, the sustained handgrip force after 0.2 mg/kg at 60 seconds was calculated to be 1.27% (95% CI [0.40, 4.03]) of the maximum force of placebo. No effect on single twitch height after 0.08 mg/kg rocuronium at four minutes after drug administration could be detected.

CONCLUSIONS

Subparalyzing doses of rocuronium show a distinct effect on muscular endurance as opposed to momentary force. The findings support the hypothesis that low doses of rocuronium act mainly by reducing muscular endurance, thereby facilitating, for example, tracheal intubation.

Comparison of the clinical performance of the flexible laryngeal mask airway in pediatric patients under general anesthesia with or without a muscle relaxant: study protocol for a randomized controlled trial

BACKGROUND

The insertion of a laryngeal mask airway (LMA) is difficult in children due to the unique features of their airways. Muscle relaxants have been reported to facilitate LMA insertion in adults; however, there is a lack of evidence supporting this in children. This trial is designed to assess the feasibility of LMA insertion with and without the use of muscle relaxants in pediatric patients under general anesthesia.

METHODS/DESIGN

This is a prospective, double-blind, single-center, parallel-arm, non-inferiority, randomized controlled trial to be conducted with participants aged 2-7 years who are undergoing elective ophthalmic surgery under general anesthesia. Participants are randomly assigned to one of two groups based on whether muscle relaxants are used (MR group, n = 64) or not used (Saline group, n = 64) prior to LMA insertion. The primary outcome is the oropharyngeal leak pressure (OLP) at a fixed gas flow of 3 L/min. The secondary outcomes are intubation time for successful insertion, ease of insertion and mask bagging, intubation attempt for successful insertion, successful insertion rate on the first attempt, fiberoptic view of the LMA position, postoperative complications, and changes in hemodynamic and ventilatory parameters.

DISCUSSION

We will compare the OLPs to determine whether the muscle relaxant provides better conditions for the manipulation of the LMA. This is the first randomized controlled trial to investigate whether muscle relaxants are beneficial to the clinical performance of LMA insertion in pediatric patients under general anesthesia. This trial will be a resource for improving the process and safety of pediatric LMA insertion under general anesthesia.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03487003 . Registered on 18 April 2018.

Optimal dose of rocuronium bromide undergoing adenotonsillectomy under 5% sevoflurane with fentanyl

OBJECTIVE

Adenotonsillectomy is a short surgical procedure under general anaesthesia in children. An ideal muscle relaxant for adenotonsillectomy would create an intense neuromuscular block while having a quick recovery time without postoperative morbidity. We compared the effect of different doses of rocuronium for the tracheal intubation in children under 5% sevoflurane and fentanyl.

MATERIALS AND METHODS

75 children (aged 3-10 years, ASA I) scheduled for adenotonsillectomy were enrolled. Anaesthesia was induced with propofol 2.5 mg/kg, followed by fentanyl 2 μg/kg. After mask ventilation with 5 vol% sevoflurane in 100% oxygen for 2 min, 2 ml of study drug was administered intravenously, i.e., either normal saline (S Group) or one of two doses (0.15 or 0.3 mg/kg) of rocuronium. We assessed conditions during tracheal intubation and also recorded the surgical condition, the time from discontinuation of sevoflurane to extubation and PAED scale, pain scores in PACU.

RESULTS

Rocuronium groups (96% and 100%, respectively; P < 0.01) showed statistically superior clinically acceptable intubating conditions than the saline group (72%). The 0.3 mg/kg rocuronium (80%) treatment clearly resulted in excellent intubating conditions compared with the 0.15 mg/kg group (44%; p = 0.028). There was no significant difference in the time to extubation and surgical condition, and in the postoperative measures of emergence delirium, pain, and recovery time among the three groups.

CONCLUSION

A dose of 0.3 mg/kg rocuronium may provide optimal intubating conditions without delayed recovery in 5% sevoflurane anaesthesia with fentanyl in children undergoing adenotonsillectomy.

CLINICAL TRIALS REGISTRY NUMBER

NCT02467595.

All India Difficult Airway Association 2016 guidelines for the management of unanticipated difficult tracheal intubation in Paediatrics

The All India Difficult Airway Association guidelines for the management of the unanticipated difficult tracheal intubation in paediatrics are developed to provide a structured, stepwise approach to manage unanticipated difficulty during tracheal intubation in children between 1 and 12 years of age. The incidence of unanticipated difficult airway in normal children is relatively rare. The recommendations for the management of difficult airway in children are mostly derived from extrapolation of adult data because of non-availability of proven evidence on the management of difficult airway in children. Children have a narrow margin of safety and mismanagement of the difficult airway can lead to disastrous consequences. In our country, a systematic approach to airway management in children is lacking, thus having a guideline would be beneficial. This is a sincere effort to protocolise airway management in children, using the best available evidence and consensus opinion put together to make airway management for children as safe as possible in our country.

Appropriate sevoflurane concentration to stabilize autonomic activity during intubation with rocuronium in infants: a randomized controlled trial

Background

In infants, sevoflurane is commonly used for induction of anesthesia, following which a muscle relaxant is administered to facilitate tracheal intubation. When rocuronium is used as the muscle relaxant, intubation may be performed before reaching an adequate depth of anesthesia because of its rapid onset. The purpose of this study was to investigate the optimal sevoflurane concentration that would minimize the impact of intubation on hemodynamics and autonomic nervous system (ANS) activity in infants.

Methods

Sixty-one infants aged 1–6 months, undergoing cleft lip repair, were enrolled. Patients were randomly assigned to three end-tidal sevoflurane concentration (E’_Sevo) groups, 3%, 4% and 5%. Anesthesia was induced with 5% sevoflurane with 100% oxygen, and rocuronium (0.6 mg/kg) was administered. The concentration of sevoflurane was adjusted to the predetermined concentration in each group. Mechanical pressure control ventilation via a face mask was commenced. Five minutes after E’_Sevo became stable at the predetermined concentration, tracheal intubation was performed. Immediately after tracheal intubation, ventilation was restarted at the same ventilator settings and continued for 150 seconds. Heart rate (HR) and mean arterial pressure (MAP) were measured 5 times in the 150 seconds after intubation. Normalized units (nu) of high frequency (HF: 0.04-0.15 Hz) and the ratio of low frequency (LF: 0.15-0.4 Hz) to HF components (LF/HF) of HR variability were calculated by MemCalc/Tonam2C™. Normalized units of HF (HFnu) and LF/HF reflect cardiac parasympathetic and sympathetic activity, respectively.

Results

After intubation, HR increased slightly in all groups and MAP increased by 9.2% in the E’_Sevo-3% group. LF/HF increased (p < 0.01) and HFnu decreased (p < 0.01) in all groups 30 seconds after intubation. HFnu was lower (p < 0.001) and LF/HF was higher (p = 0.007) in the E’_Sevo-3% group than in E’_Sevo-5% group. ANS responses to intubation were reduced in a dose-dependent manner.

Conclusions

Sympathomimetic and parasympatholytic responses to intubation in the E’_Sevo-3% group were much greater than those in the E’_Sevo-5% group. During tracheal intubation in infants, 4% or 5% sevoflurane is appropriate for prevention of sympathetic hyperactivation and maintenance of ANS balance as compared to 3% sevoflurane, when a muscle relaxant is co-administered.

Trial registration

The study was registered at UMIN-CTR (UMIN000009933).

Development of a guideline for the management of the unanticipated difficult airway in pediatric practice

BACKGROUND

Most airway problems in children are identified in advance; however, unanticipated difficulties can arise and may result in serious complications. Training for these sporadic events can be difficult. We identified the need for a structured guideline to improve clinical decision making in the acute situation and also to provide a guide for teaching.

OBJECTIVE

Guidelines for airway management in adults are widely used; however, none have been previously devised for national use in children. We aimed to develop guidelines for the management of the unanticipated difficult pediatric airway for use by anesthetists working in the nonspecialist pediatric setting.

METHOD

We reviewed available guidelines used in individual hospitals. We also reviewed research into airway management in children and graded papers for the level of evidence according to agreed criteria. A Delphi panel comprising 27 independent consultant anesthetists considered the steps of the acute airway management guidelines to reach consensus on the best interventions to use and the order in which to use them. If following the literature review and Delphi feedback, there was insufficient evidence or lack of consensus, regarding inclusion of a particular point; this was reviewed by a Second Specialist Group comprising 10 pediatric anesthetists.

RESULTS

Using the Delphi group's deliberations and feedback from the Second Specialist Group, we developed three guidelines for the acute airway management of children aged 1-8 years.

CONCLUSIONS

This paper provides the background, available evidence base, and justification for each step in the resultant guidelines and gives a rationale for their use.

Dose of rocuronium for rapid tracheal intubation following remifentanil 2 μg kg-1 and propofol 2 mg kg-1

CONTEXT

Full relaxation is not mandatory for successful tracheal intubation.

OBJECTIVE

We tried to find the dose of rocuronium that gave acceptable intubation conditions in a rapid sequence intubation with remifentanil and propofol.

DESIGN

A dose-finding study of rocuronium using a modified Dixon's up-and-down method.

SETTING

A single tertiary care teaching hospital.

PARTICIPANTS

Patients undergoing elective surgery under general anaesthesia.

INTERVENTIONS

After premedication with midazolam and glycopyrrolate, anaesthesia was induced using remifentanil 2 μg kg and propofol 2 mg kg, and a predetermined dose of rocuronium was administered. The dose of rocuronium was determined by a modified Dixon's up-and-down method starting from 0.8 mg kg with an interval of 0.1 or 0.05 mg kg. Intubation was performed 60 s after the start of the rocuronium injection. Intubation conditions were graded as excellent, good or poor. Excellent or good were regarded as clinically acceptable.

MAIN OUTCOME MEASURE

A dose of rocuronium needed for acceptable intubation condition in 50% of patients (ED50) during rapid tracheal intubation after induction of anaesthesia with remifentanil and propofol.

RESULTS

Twenty-eight patients were enrolled to obtain six crossovers. The ED50 of rocuronium was 0.20 mg kg (95% confidence interval, CI 0.17 to 0.23 mg kg) by a modified Dixon's up-and-down method.

CONCLUSION

After induction of anaesthesia with remifentanil 2 μg kg and propofol 2 mg kg, the ED50 of rocuronium for acceptable intubation condition was 0.20 mg kg (95% CI, 0.17 to 0.23 mg kg) for rapid sequence intubation. Thus, we recommend that the intubation dose should be 0.8 mg kg.

TRIAL REGISTRATION

Clinical trial registration KCT0000094.

Intubation time required for tracheal intubation with low-dose rocuronium in children with and without atropine

PURPOSE

The purpose of this study was to determine the intubation time needed to facilitate tracheal intubation (Time(EI)) with a low dose of rocuronium (0.3 mg/kg) during propofol induction, and to determine whether this time was reduced by the administration of atropine.

METHODS

Forty-six children, aged 3-10 years, were randomly assigned to receive either saline (control group) or atropine 10 μg/kg (atropine group). Anesthesia was induced with alfentanil 10 μg/kg, propofol 2.5 mg/kg, and rocuronium 0.3 mg/kg. Each Time(EI) at which tracheal intubation was attempted was predetermined according to the up-and-down method. The values of Time(EI) that provided excellent intubation conditions in 50 and 95 % of patients were defined as Time(EI)50 and Time(EI)95, respectively.

RESULTS

Time(EI)50 ± SD was 160 ± 26.2 and 150 ± 13.7 s in the control and atropine groups, respectively. Using isotonic regression, Time(EI)95 in the control and atropine groups was 199 s (95 % CI 198.8-200.7 s) and 171 s (95 % CI 171.3-172.1 s), respectively. Time(EI)95 was significantly higher in the control group than in the atropine group (P < 0.001). HR was significantly higher in the atropine group than in the control group during the study period.

CONCLUSIONS

This study demonstrated that the Time(EI)95 of a low dose of rocuronium (0.3 mg/kg) required for excellent tracheal intubation was 199 s during i.v. anesthesia induction using propofol and alfentanil in children. Also, i.v. atropine (10 μg/kg) before anesthesia induction was able to reduce Time(EI)95 by 28 s.

Neuromuscular blocking agent administration for emergent tracheal intubation is associated with decreased prevalence of procedure-related complications

BACKGROUND

Emergent intubation is associated with a high rate of complications. Neuromuscular blocking agents are routinely used in the operating room and emergency department to facilitate intubation. However, use of neuromuscular blocking agents during emergent airway management outside of the operating room and emergency department is controversial. We hypothesized that the use of neuromuscular blocking agents is associated with a decreased prevalence of hypoxemia and reduced rate of procedure-related complications.

METHODS

Five hundred sixty-six patients undergoing emergent intubations in two tertiary care centers, Massachusetts General Hospital, Boston, MA, and the University of California Los Angeles, Ronald Reagan Medical Center, Los Angeles, CA, were enrolled in a prospective, observational study. The 112 patients intubated during cardiopulmonary resuscitation were excluded, leaving 454 patients for analysis. All intubations were supervised by attendings trained in Critical Care Medicine. We measured intubating conditions, oxygen saturation during and 5 mins following intubation. We assessed the prevalence of procedure-related complications defined as esophageal intubation, traumatic intubation, aspiration, dental injury, and endobronchial intubation.

RESULTS

The use of neuromuscular blocking agents was associated with a lower prevalence of hypoxemia (10.1% vs. 17.4%, p = .022) and a lower prevalence of procedure-related complications (3.1% vs. 8.3%, p = .012). This association persisted in a multivariate analysis, which controlled for airway grade, sedation, and institution. Use of neuromuscular blocking agents was associated with significantly improved intubating conditions (laryngeal view, p = .014; number of intubation attempts, p = .049). After controlling for the number of intubation attempts and laryngoscopic view, muscle relaxant use is an independent predictor of complications associated with emergency intubation (p = .037), and there is a trend towards improvement of oxygenation (p = .07).

CONCLUSION

The use of neuromuscular blocking agents, when used by intensivists with a high level of training and experience, is associated with a decrease in procedure-related complications.

Neuromuscular blocking agents for electroconvulsive therapy: a systematic review

Electroconvulsive therapy (ECT) is the transcutaneous application of small electrical stimuli to the brain to induce generalised seizures for the treatment of selected psychiatric disorders. The clinical indications for ECT as an effective therapeutic modality have been considerably expanded since its introduction. Anaesthesia and neuromuscular blocking agents (NMBAs) are required to ensure patients' safety during ECT. The optimal dose of muscle relaxant for ECT reduces muscle contractions without inducing complete paralysis. Slight residual motor convulsive activity is helpful in ascertaining that a seizure has occurred, while total paralysis prolongs the procedure unnecessarily. Suxamethonium is commonly used, but nondepolarising NMBAs are indicated in patients with certain comorbidities. In this review, we summarise current concepts of NMBA management for ECT.

Role of muscle relaxants in pediatric anesthesia

PURPOSE OF REVIEW

Changes in practice and the development of new anesthetic drugs have influenced the use of muscle relaxants in children. This article reviews these developments, and defines the current role and factors affecting the choice of muscle relaxant drugs in pediatric anesthesia.

RECENT FINDINGS

The introduction of the laryngeal mask airway as a means of controlling the pediatric airway has reduced the need for muscle relaxants. In cases requiring tracheal intubation, however, a balanced anesthetic technique incorporating a nondepolarizing relaxant provides the best intubating conditions with the minimal potential for adverse effects. The introduction of newer less-toxic, shorter-acting anesthetic drugs has reduced the requirement for muscle relaxants during surgery. Moderate anesthesia with sevoflurane-remifentanil or propofol-remifentanil can keep patients immobile without producing hypotension and facilitate controlled ventilation once the effects of the intubating dose of a muscle relaxant have worn off.

SUMMARY

Recent developments in clinical practice have reduced or obviated the need for muscle relaxants in pediatric anesthesia. Muscle relaxants are still indicated for intubation and procedures requiring profound muscle relaxation, and to minimize the amounts of anesthetic drugs given to infants and sick children. Specific relaxants and doses can be chosen to suit the clinical circumstances.

Tracheal intubating conditions and pharmacodynamics following cisatracurium in infants and children undergoing halothane and thiopental-fentanyl anesthesia

BACKGROUND

The aims of the present study were to determine the tracheal intubating conditions, onset time, duration of action, and hemodynamic responses following the administration of cisatracurium 0.15 mg x kg(-1) to infants and children.

METHODS

One hundred and eighty-one infants and children aged 1 month to 12 years were randomized to two groups to receive anesthesia with nitrous oxide-oxygen-halothane (group H) or nitrous oxide-oxygen-thiopental-fentanyl (group TF). Intubation conditions were assessed 120 s after cisatracurium administration using a 4-part scale. Neuromuscular transmission was monitored by recording the evoked compound electromyogram of the adductor pollicis.

RESULTS

The proportion of patients with excellent or good intubating conditions was similar in both groups (88 of 90, 98% in group H; 85 of 90, 94% in group TF). However, there was a significantly greater proportion of excellent intubating conditions in group H (79 of 90, 88%) compared with group TF (65 of 90, 72%) (P = 0.01) and recovery time was significantly longer in group H compared with group TF (P < 0.001). There was also a higher proportion of excellent intubating conditions in infants compared with older subjects (P = 0.02) and a shorter onset time (P < 0.001) and longer recovery time (P < 0.001) in younger compared with older patients. Changes in heart rate and arterial pressure were negligible 1 min following the cisatracurium administration.

CONCLUSIONS

Cisatracurium 0.15 mg x kg(-1) produces acceptable intubating conditions at 120 s in the great majority of infants and children. Anesthesia background and age have significant effects on intubating conditions and duration of action of cisatracurium.

Pharmacodynamics of rocuronium 0.3 mg kg(-1) in adult patients with and without renal failure

BACKGROUND AND AIM

The neuromuscular effects of a bolus dose of rocuronium 0.6 mg kg(-1) under propofol anaesthesia in renal failure patients are prolonged compared to healthy patients. The present study aims to describe the neuromuscular effects of 0.3 mg kg(-1) rocuronium under propofol anaesthesia in patients with renal failure and to compare these effects with healthy control patients.

METHODS

With institutional approval and informed consent, 18 healthy patients and 18 patients with renal failure took part in this prospective open label study. The renal failure patients were undergoing either renal transplantation or insertion of a shunt. Rocuronium 0.3 mg kg(-1) was given intravenously after induction of anaesthesia with propofol 1-2 mg kg(-1) and fentanyl 2 microg kg(-1). Propofol 6-12 mg kg(-1) h(-1) was used for maintenance of anaesthesia. Four acceleromyographic responses of the thumb after supramaximal stimulation of the ulnar nerve using surface electrodes at 2 Hz every 15 s were measured and recorded. The onset time, the time to recovery of the first twitch to 25% recovery and the time to a train-of-four ratio of 0.7 were all recorded. Wilcoxon rank sum testing was used to compare the pharmacodynamics and to see if medication, gender or electrolytes influenced the duration of the block. P < 0.05 was significant.

RESULTS

No statistical differences were seen in the neuromuscular blocking effects of rocuronium between the two groups but there was a significant difference (P < 0.00001) in the variability of the total duration of the block.

CONCLUSIONS

Rocuronium 0.3 mg kg(-1) is suitable for use in patients with renal failure when endotracheal intubation and neuromuscular block for a short period of time are needed. Tracheal intubation is facilitated within 4 min and the block can be antagonized within 20 min.

Use of low-dose rocuronium for intubation of children during volunteer surgery abroad

BACKGROUND

Low-dose rocuronium (ROC) might improve safety during volunteer surgery abroad (VSA) by facilitating intubation with a lower halothane concentration than is typically used. We hypothesized that 0.25 mg.kg(-1) of ROC would improve intubation conditions during 3% halothane induction and still allow for rapid return to spontaneous ventilation (SV).

METHODS

During Operation Smile's 2002 mission to Honduras, patients aged 3 months-11 years were randomized to receive ROC 0.25 mg.kg(-1) (n = 19), or placebo (n = 23). Induction was with 3% halothane in 100% O(2), with ventilation assisted and controlled when possible, and normocarbia maintained. An i.v. was placed after induction, and ROC or placebo given. Direct laryngoscopy (DL) was performed 3 min later by a blinded laryngoscopist who assessed conditions according to predetermined criteria.

RESULTS

Adequate intubation conditions occurred in 89 and 87% of patients (P = 0.59), and mean times from DL until the return to SV were 9.8 and 4.3 min (P = 0.003), in the ROC and placebo groups, respectively. For the placebo group, the presence of SV at DL was predictive of inadequate intubation conditions (P = 0.006).

CONCLUSIONS

When administering 3% halothane for induction of VSA patients, a high frequency of adequate intubation conditions can be achieved without a relaxant, rendering the known benefits of 0.25 mg.kg(-1) of ROC unapparent. ROC 0.25 mg.kg(-1) does allow rapid return to SV.

Low doses of rocuronium during remifentanil-propofol-based anesthesia in children: comparison of intubating conditions

BACKGROUND

In this prospective double-blind study, intubation conditions were compared at 90 s following two different low doses of rocuronium during remifentanil and propofol anesthesia in children undergoing ambulatory procedures.

METHODS

Forty-four children (ASA I-II, aged 3-12 years) undergoing day case ENT surgery were premedicated with midazolam 0.5 mg x kg(-1). Following atropine 10 microg x kg(-1), remifentanil infusion 0.5 microg x kg(-1) x min(-1) was started. After 60 s, anesthesia was induced with propofol 2.5 mg x kg(-1). Immediately after a bolus dose of propofol, the children received rocuronium doses of 0.15 mg x kg(-1) (group I, n = 22) or 0.3 mg x kg(-1) (group II, n = 22) in a randomized manner, after which an infusion of propofol 6 mg x kg(-1) h(-1) was added to the infusion of remifentanil 0.5 microg x kg(-1) min(-1) for maintenance of anesthesia. Intubating conditions were evaluated 90 s after rocuronium administration applying the Copenhagen Scoring System which included components of laryngoscopy, vocal cord movement and reaction to intubation. Hemodynamic values were recorded at predetermined time intervals.

RESULTS

Excellent, good and poor intubation conditions were 18.2, 40.9 and 40.9% in group I and 40.9, 54.5 and 4.5% in group II. Clinically acceptable intubating conditions (excellent and good) were significantly higher in group II (95.5%) than in group I (59.1%) (P = 0.004). Mean values of heart rate and blood pressure did not differ significantly between groups. No children required any intervention for hemodynamic instability and/or muscle rigidity.

CONCLUSIONS

The results suggest that 0.3 mg x kg(-1) of rocuronium may be a better low dose than 0.15 mg x kg(-1) of rocuronium for clinically acceptable intubating conditions in pediatric ambulatory surgery during remifentanil-propofol-based anesthesia at the doses used in the study.

Optimal rocuronium dose for intubation during inhalation induction with sevoflurane in children

BACKGROUND

We studied 120 children aged 2-7 yr in a prospective, randomized, assessor-blinded fashion to define the optimal rocuronium dose which provides a 95% probability of acceptable intubation conditions (ED95TI) during inhalation induction with sevoflurane.

METHODS

After inhalation induction with 8% sevoflurane in 60% nitrous oxide and 40% oxygen, and loss of the eyelash reflex, we administered rocuronium (0.1, 0.15, 0.22, 0.3, or 0.6 mg kg-1) or placebo. We quantified neuromuscular function by stimulation of the ulnar nerve at 0.1 Hz to produce contraction of the adductor pollicis muscle using accelerometry. Intubation conditions were assessed 2 min after test drug injection. The optimal rocuronium dose was defined as the lowest dose, which allowed acceptable intubation conditions in 95% of children (ED95TI).

RESULTS

Two minutes after injection of placebo or rocuronium, intubation conditions were acceptable in 35, 45, 80, 90, 95, and 100% of children, respectively. Rocuronium 0.07 [CI 0.02-0.11], 0.24 [0.19-0.31], and 0.29 [0.23-0.38] mg kg-1 provided 50, 90, and 95% probability of acceptable intubating conditions. When thumb acceleration was depressed by 50% or more, intubating conditions were considered acceptable in 97% of children. Recovery of the train-of-four ratio to 0.8 averaged 12 (7), 16 (7), 24 (7), 24 (8), and 50 (22) min after the respective dose of rocuronium.

CONCLUSIONS

During inhalation induction with 8% sevoflurane in 60% nitrous oxide, rocuronium 0.29 mg kg-1 (ED95) optimizes intubation conditions for surgery of short duration.