A survey of practice of tracheal intubation without muscle relaxant in paediatric patients

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.

Guidelines on muscle relaxants and reversal in anaesthesia

OBJECTIVES

To provide an update to the 1999 French guidelines on "Muscle relaxants and reversal in anaesthesia", a consensus committee of sixteen experts was convened. A formal policy of declaration and monitoring of conflicts of interest (COI) was developed at the outset of the process and enforced throughout. The entire guidelines process was conducted independently of any industrial funding (i.e. pharmaceutical, medical devices). The authors were required to follow the rules of the Grading of Recommendations, Assessment, Development and Evaluation (GRADE®) system to assess the quality of the evidence on which the recommendations were based. The potential drawbacks of making strong recommendations based on low-quality evidence were stressed. Few of the recommendations remained ungraded.

METHODS

The panel focused on eight questions: (1) In the absence of difficult mask ventilation criteria, is it necessary to check the possibility of ventilation via a facemask before muscle relaxant injection? Is it necessary to use muscle relaxants to facilitate facemask ventilation? (2) Is the use of muscle relaxants necessary to facilitate tracheal intubation? (3) Is the use of muscle relaxants necessary to facilitate the insertion of a supraglottic device and management of related complications? (4) Is it necessary to monitor neuromuscular blockade for airway management? (5) Is the use of muscle relaxants necessary to facilitate interventional procedures, and if so, which procedures? (6) Is intraoperative monitoring of neuromuscular blockade necessary? (7) What are the strategies for preventing and treating residual neuromuscular blockade? (8) What are the indications and precautions for use of both muscle relaxants and reversal agents in special populations (e.g. electroconvulsive therapy, obese patients, children, neuromuscular diseases, renal/hepatic failure, elderly patients)? All questions were formulated using the Population, Intervention, Comparison and Outcome (PICO) model for clinical questions and evidence profiles were generated. The results of the literature analysis and the recommendations were then assessed using the GRADE® system.

RESULTS

The summaries prepared by the SFAR Guideline panel resulted in thirty-one recommendations on muscle relaxants and reversal agents in anaesthesia. Of these recommendations, eleven have a high level of evidence (GRADE 1±) while twenty have a low level of evidence (GRADE 2±). No recommendations could be provided using the GRADE® system for five of the questions, and for two of these questions expert opinions were given. After two rounds of discussion and an amendment, a strong agreement was reached for all the recommendations.

CONCLUSION

Substantial agreement exists among experts regarding many strong recommendations for the improvement of practice concerning the use of muscle relaxants and reversal agents during anaesthesia. In particular, the French Society of Anaesthesia and Intensive Care (SFAR) recommends the use of a device to monitor neuromuscular blockade throughout anaesthesia.

Management of the child's airway under anaesthesia: The French guidelines

OBJECTIVE

To provide French guidelines about "Airway management during paediatric anaesthesia".

DESIGN

A consensus committee of 17 experts from the French Society of Anaesthesia and Intensive Care Medicine (Société Française d'Anesthésie-Réanimation, SFAR) and the Association of French speaking paediatric anaesthesiologists and intensivists (Association Des Anesthésistes Réanimateurs Pédiatriques d'Expression Francophone, ADARPEF) was convened. The entire process was conducted independently of any industry funding. The authors followed the principles of the Grading of Recommendations Assessment, Development and Evaluation (GRADE®) system to assess the quality of evidence. The potential drawbacks of making strong recommendations in the presence of low-quality evidence were emphasised. Few recommendations were not graded.

METHODS

The panel focused on 7 questions: 1) Supraglottic Airway devices 2) Cuffed endotracheal tubes 3) Videolaryngoscopes 4) Neuromuscular blocking agents 5) Rapid sequence induction 6) Airway device removal 7) Airway management in the child with recent or ongoing upper respiratory tract infection. Population, intervention, comparison, and outcomes (PICO) questions were reviewed and updated as needed, and evidence profiles were generated. The analysis of the literature and the redaction of the recommendations were then conducted according to the GRADE® methodology.

RESULTS

The SFAR Guideline panel provides 17 statements on "airway management during paediatric anaesthesia". After two rounds of discussion and various amendments, a strong agreement was reached for 100% of the recommendations. Of these recommendations, 6 have a high level of evidence (Grade 1 ± ), 6 have a low level of evidence (Grade 2 ± ) and 5 are experts' opinions. No recommendation could be provided for 3 questions.

CONCLUSIONS

Substantial agreement exists among experts regarding many strong recommendations for paediatric airway management.

Using fentanyl and propofol for tracheal intubation during sevoflurane induction without muscle relaxants in children: A randomized prospective study

Context:

Tracheal intubation is frequently facilitated with sevoflurane induction without the use of muscle relaxants in children.

Aim:

The aim of this study was to compare the effects of two different doses of propofol preceded by a fixed dose of fentanyl during sevoflurane induction on quality of tracheal intubation in children.

Settings and Design:

This was a prospective randomized study.

Subjects and Methods:

Ninety American Society of Anesthesiologists I-II children aged 2–6 years were randomly assigned to one of two equal groups to receive 2 μg/kg of fentanyl with 2 mg/kg of propofol (Group I) or 2 μg/kg of fentanyl with 3 mg/kg of propofol (Group II) during sevoflurane induction. The intubating conditions and hemodynamic responses were evaluated. The time from sevoflurane induction to loss of consciousness, to intravenous line insertion, and to intubation was measured. The occurrence of any adverse effect was recorded.

Statistical Analysis Used:

Results were analyzed using Student's t-test, paired t-test, and Chi-square test. P < 0.05 was considered statistically significant.

Results:

The incidence of excellent intubating conditions was achieved more significantly in Group II (41/45 patients, 91%) than that in Group I (31/45 patients, 69%) (P = 0.008) (95% confidence interval [CI] =0.39–0.8). Whereas, there were no significant differences between the two groups in terms of the overall acceptable intubating conditions in Group I (40/45 patients, 89%) and Group II (43/45 patients, 96%) (P = 0.81) (95% CI = 0.71–1.31). No patient developed any adverse effect.

Conclusion:

The administration of 3 mg/kg propofol preceded by 2 μg/kg fentanyl provided a higher proportion of excellent intubating conditions compared with 2 mg/kg propofol preceded by 2 μg/kg fentanyl during sevoflurane induction in children without muscle relaxants.

Intranasal dexmedetomidine premedication reduces the minimum alveolar concentration of sevoflurane for tracheal intubation in children: a randomized trial

STUDY OBJECTIVE

To determine the effects of dexmedetomidine premedication on the minimum alveolar concentration of sevoflurane for tracheal intubation (MACTI) in children.

DESIGN

Prospective, randomized, clinical comparison study.

SETTING

Operating room of an academic hospital.

PATIENTS

90 pediatric, ASA physical status 1 patients, aged 3 to 7 years, scheduled for minor elective surgery.

INTERVENTIONS

Patients were randomized to three groups to receive placebo, dexmedetomidine 1 μg/kg, or dexmedetomidine 2 μg/kg approximately 60 minutes before anesthesia. Anesthesia was induced with sevoflurane. Each concentration of sevoflurane for which a tracheal intubation was attempted was predetermined according to modification of the Dixon's up-and-down method, with 0.25% as a step size and held constant for at least 15 minutes before tracheal intubation. All responses ("movement" or "no movement") to tracheal intubation were assessed.

MEASUREMENTS AND MAIN RESULTS

The MACTI of sevoflurane was 2.82% ± 0.17% in the control group, 2.26% ± 0.18% in the 1 μg/kg dexmedetomidine group, and 1.83% ± 0.16% in the 2 μg/kg dexmedetomidine group. Dexmedetomidine premedication (1 and 2 μg/kg) decreased the MACTI of sevoflurane by 20% and 35%, respectively. There were no clinically significant episodes of hypotension or bradycardia in any patients.

CONCLUSION

Intranasal dexmedetomidine premedication produces a dose-dependent decrease in the concentration of sevoflurane needed for tracheal intubation in children.

Dose requirements of remifentanil for intubation in nonparalyzed Chinese children

BACKGROUND

The objective of this study was to determine ED50 and ED95 of remifentanil for intubation combined with propofol in nonparalyzed Chinese children.

METHODS

Forty-seven American Society of Anesthesiologists Class I children aged 4-11 years weighing 14-33.5 kg underwent general anesthesia with 2.5 mg·kg(-1) of intravenous propofol followed by remifentanil in Wenzhou, China. The initial dose of remifentanil was 2.5 μg·kg(-1) injected over 60 s. Intubation was attempted 30 s after the completion of remifentanil injection. Level of difficulty to intubate was graded on a scoring system. If the initial intubation condition was deemed satisfactory, subsequent remifentanil doses were decreased by 0.25 μg·kg(-1). If the intubating condition was deemed unsatisfactory, subsequent remifentanil doses were increased by 0.25 μg·kg(-1). Mean arterial pressure, heart rate, and pulse oximetry were documented before and after induction, immediately after intubation, and 1 min after intubation.

RESULTS

The ED50 of remifentanil used to render a satisfactory intubating condition used in combination with 2.5 mg·kg(-1) of propofol in nonparalyzed Chinese children was 2.30 μg·kg(-1) (95% confidence interval: 2.28-2.31 μg·kg(-1)), and the ED95 is 2.75 μg·kg(-1) (95% confidence interval: 2.59-3.35 μg·kg(-1)). These doses were lower than previously reported.

CONCLUSION

When used in combination with 2.5 mg·kg(-1) of intravenous propofol, ED50 and ED95 of remifentanil for adequate intubation in nonparalyzed children were lower than previously reported, at 2.30 and 2.75 μg·kg(-1), respectively.

Pediatric ambulatory anesthesia

Pediatric patients often undergo anesthesia for ambulatory procedures. This article discusses several common preoperative dilemmas, including whether to postpone anesthesia when a child has an upper respiratory infection, whether to test young women for pregnancy, which children require overnight admission for apnea monitoring, and the effectiveness of nonpharmacological techniques for reducing anxiety. Medication issues covered include the risks of anesthetic agents in children with undiagnosed weakness, the use of remifentanil for tracheal intubation, and perioperative dosing of rectal acetaminophen. The relative merits of caudal and dorsal penile nerve block for pain after circumcision are also discussed.

[General anaesthesia in children: a French survey of practices]

INTRODUCTION

The practice of pediatric anesthesia requires a regular update of scientific knowledge and technical skills. To provide the most adequate Continuing Medical Education programs, it is necessary to assess the practices of pediatric anesthesiologists. Thus, the objective of this survey was to draw a picture of the current clinical practices of general anesthesia in children, in France.

MATERIAL AND METHODS

One thousand one hundred and fifty questionnaires were given to anesthesiologists involved in pediatric cases. These questionnaires collected information on various aspects of clinical practice relative to induction, maintenance, recovery from general anaesthesia and also classical debated points such as children with Upper Respiratory Infection (URI), emergence agitation, epileptoid signs or anaesthetic management of adenoidectomy. Differences in practices between CHG (general hospital), CHU (teaching hospital), LIBERAL (private) and PSPH (semi-private) hospitals were investigated.

RESULTS

There were 1025 questionnaires completed. Fifty-five percent of responders worked in public hospitals (CHG and CHU); 77% had a practice that was 25% or less of pediatric cases. In children from 3 to 10 years: 72% of respondents used always premedication and two thirds performed inhalation induction in more than 50% of cases. For induction, 53% used sevoflurane (SEVO) at 7 or 8%. Respondents from LIBERAL used higher SEVO concentrations. Tracheal intubation was performed with SEVO alone (37%), SEVO and propofol (55%) and SEVO with myorelaxant (8%), 93% of respondents used a bolus of opioid. For maintenance, the majority of respondents used SEVO associated with sufentanil; desflurane and remifentanil were more frequently used in CHU. Two thirds of respondents used N(2)O. Depth of anesthesia was commonly assessed by hemodynamic changes (52%), end tidal concentration of halogenated (38%) or automated devices based on EEG (7%). In children with URI, 98% of respondents used SEVO for anesthesia. To control the airway 42% used a tracheal tube, 30% a laryngeal mask and 20% a facial mask. Emergence agitation was an important concern for two thirds of respondents, while epileptoid signs were considered as important by only 20%. Eighty-nine percent of respondents practiced anesthesia for adenoidectomy. Anesthesia was induced by inhalation of SEVO 7-8% (41%), 6% (39%) or 4% (12%), 66% put an intravenous line (less frequently in LIBERAL). 67% of the responders managed adenoidectomy without any device to control the airway (more frequently in LIBERAL), 32% administrated a bolus of opioid (less frequently in LIBERAL).

DISCUSSION

This survey demonstrated that the practices regarding general anesthesia in children are relatively homogenous. Most of the differences appeared between LIBERAL and the others structures; the anaesthetic management for adenoidectomy illustrates these findings.

The effect of adjuvant drugs on the quality of tracheal intubation without muscle relaxants in children: a systematic review of randomized trials

Intubation without prior administration of muscle relaxants is a common practice in children. However, succinylcholine may be considered as the golden standard for optimizing intubating conditions. We conducted a systematic review of the literature to identify drug combinations that included induction of anesthesia with sevoflurane or propofol. Our aim was to select drug combinations that yield excellent intubating conditions ≥80%; we identified six combinations in children aged 1-9 years. Sevoflurane with remifentanil (1 or 2 μg·kg(-1) ), lidocaine (2 mg·kg(-1) ), or propofol (2 mg·kg(-1) ) as the adjuvant shared the following characteristics: premedication with midazolam and/or ketamine, long sevoflurane exposure time, high inspired and endtidal sevoflurane concentration, and assisted ventilation. One combination using sevoflurane with propofol (3 mg·kg(-1) ) without premedication, with shorter sevoflurane exposure time, and spontaneous breathing indicated that propofol may be the adjuvant of choice for a rapid sevoflurane induction. The only adjuvant identified in propofol induction was remifentanil (4 μg·kg(-1) ). No serious adverse events were reported with these combinations.

Optimal dose of propofol for intubation after sevoflurane inhalation without neuromuscular blocking agent in children

BACKGROUND

This study was designed to determine the optimal dose of propofol for excellent intubating conditions in children without neuromuscular blockade at various alveolar concentrations of sevoflurane.

METHODS

Sixty-three children, aged 0.5-5 years, were randomized to three groups of end-tidal sevoflurane concentration (ETsevo) 3%, 3.5%, and 4%. Inhalation anesthesia was started with sevoflurane 7% in 100% oxygen. When the patients became unconscious, inspired concentration was adjusted to obtain the target ETsevo for each group. When ETsevo reached the target concentration, a predetermined dose of propofol was given and tracheal intubation was performed. The proper dose of propofol was determined using the 'up-and-down' method.

RESULTS

The median dose (95% confidence intervals) of propofol for excellent tracheal intubating conditions in 50% of children were 1.25 mg/kg (0.84-1.75) at ETsevo of 3%, 0.76 mg/kg (0.35-1.21) at 3.5%, and 0.47 mg/kg (0.26-1.09) at 4%. The frequency of adverse effects was not different between groups during induction and recovery.

CONCLUSION

Propofol 1.5-2 mg/kg provides excellent intubating conditions at 3-4% ETsevo in children without using any neuromuscular blocking agent.

Evidence for the need for anaesthesia in the neonate

Neonates are both capable of experiencing pain and memory formation, albeit implicit memory. During surgical procedures, insufficient ablation of the stress response and possible implicit memory formation of intra-operative events might result in adverse early and long-term outcomes. Neonates deserve the same respect as adult patients. It is thus the responsibility of the anaesthetist to provide sufficient anaesthesia for neonates undergoing surgery. A critical approach in weighing the risks and benefits of exposing a neonate to anaesthesia is prudent, and truly elective surgery should be delayed.

The effect of age on the dose of remifentanil for tracheal intubation in infants and children

INTRODUCTION

This study aimed to determine the age-specific bolus dose of remifentanil (ED(50)) to facilitate tracheal intubation without the use of neuromuscular blocking agents.

METHODS

ASA 1-2 subjects were recruited into three groups of 0-3 months (group I), 4-12 months (group II), and 1-3 years (group III) of age. A sequential up-and-down design determined the remifentanil bolus dose, which was initially started at 3 mcg x kg(-1) and adjusted in 1 mcg x kg(-1) increments (range 1-6 mcg x kg(-1)). Following pretreatment with glycopyrrolate 10 microg x kg(-1) and an induction dose of propofol 5 mg x kg(-1), remifentanil was administered with a blinded study investigator commencing tracheal intubation after 60 s. After tracheal intubation, the time to return of spontaneous ventilation was measured. Logistic regression was used to predict the ED(50) and ED(95) of remifentanil.

RESULTS

Sixty-four subjects were recruited. Tracheal intubation was successful at first attempt in over 90% of subjects in each age group. Satisfactory intubating conditions were achieved in 85%, 63%, and 75% of subjects in groups I, II, and III, respectively. The logistic regression results for ED(50) (95% CI) were 3.1 (2.5-3.8), 3.7 (2.0-5.4), and 3.0 (2.1-3.9) mcg x kg(-1), and ED(95) (95% CI) were 5.0 (3.0-7.0), 9.4 (1.5-17.4), and 5.6 (2.9-8.4) mcg x kg(-1) in groups I, II, and III, respectively. Infants aged 4-12 months (group II) showed a marked variability in dose response; however, the mean ED(50) and ED(95) were not different to groups I and III. Older children had a longer duration of apnea than infants, 331 vs 180 s (P < 0.05).

DISCUSSION

The ED(50) of remifentanil for tracheal intubation was higher in all age groups than previously reported. Ideal intubating conditions were achieved in 50% of subjects with remifentanil doses of 3.1-3.7 mcg x kg(-1). Higher doses will be required for higher success rates and with anticholinergic pretreatment, doses of up to 6 mcg x kg(-1) were tolerated, without adverse effects, in two patients. Further investigation of the variability in dose response in infants and assessment of the safety this technique is warranted.

Effect of Remifentanil on Tracheal Intubation Conditions and Haemodynamics in Children Anaesthetised with Sevoflurane and Nitrous Oxide

This study examined the effect of remifentanil added to inhalation agents on intubating conditions in children (aged one to seven years). As is our routine, all patients were premedicated with 0.004 mg/kg glycopyrrolate intramuscularly 30 minutes before anaesthesia to prevent bradycardia and salivary secretion, and received intravenous 1 mg/kg ketamine prior to transfer into the operating room to facilitate separation of the child from the parents. Laryngoscopy was attempted after ventilation with 8% sevoflurane in 50% nitrous oxide and 50% oxygen for two minutes, and intravenous administration of either a placebo bolus of saline (Group S) or one of two doses of remifentanil, 1 μg/kg (Group R1) or 2 μg/kg (Group R2) given over 30 seconds, commenced at the beginning of the sevoflurane administration. Only 18 of 32 patients (56.3%) in Group S had acceptable intubating conditions compared with 31 of 32 patients (96.9%) in Group R1 and 32 of 32 patients (100%) in Group R2 (P <0.001). Mean blood pressure was lower in Group R1 and R2 compared with Group S (P <0.005). Our routine use of ketamine and glycopyrrolate may have influenced the relative lack of significant hypotension and bradycardia. Sevoflurane, nitrous oxide and remifentanil provided acceptable conditions for tracheal intubation in children and could be an acceptable alternative to intravenous induction and neuromuscular blocking agents.

Propofol for tracheal intubation in children anesthetized with sevoflurane: a dose-response study

BACKGROUND

Tracheal intubation during sevoflurane induction is frequently facilitated with i.v. propofol. We designed a dose-response study to evaluate the intubating conditions, and the incidence and duration of apnea after i.v. propofol in children.

METHODS/MATERIALS

Sixty healthy children were randomly assigned to 0, 0.5, 1, 2 or 3 mg x kg(-1) i.v. propofol during sevoflurane/nitrous oxide anesthesia. Tracheal intubation was performed approximately 30 s after propofol by an anesthesiologist who was blind to the treatment. The anesthesiologist assessed the responses to laryngoscopy and intubation using a standardized scale. Incidence and duration of apnea after propofol as well as heart rate, and systolic blood pressure before and after laryngoscopy were recorded. Data were analyzed using one-way and repeated measures ANOVA, the Jonckheere-Terpstra test, and logistic regression, with P < 0.05 accepted.

RESULTS

The laryngoscopy score after 3 mg x kg(-1) propofol was less than that after 0 mg x kg(-1) (P < 0.01) and 0.5 mg x kg(-1) (P < 0.05). Incidence of apnea after propofol 3 mg x kg(-1), 8/10, was greater than after 0 mg x kg(-1), 3/14 (P < 0.011) and 0.5 mg x kg(-1), 3/12 (P < 0.03). Duration of apnea after 3 mg x kg(-1) was greater than after 0 and 0.5 mg x kg(-1) (P < 0.01). The risk of apnea increased 1.83 fold for each 1 mg x kg(-1) dose increase in propofol (P < 0.01). Mean heart rate and systolic pressure decreased with the main effect, time.

CONCLUSION

During sevoflurane/nitrous oxide anesthesia, propofol 3 mg x kg(-1) provides superior intubating conditions with an increased incidence of and prolonged apnea compared with 0 and 0.5 mg x kg(-1).

Muscle relaxant use for tracheal intubation in pediatric anaesthesia: a survey of clinical practice in Germany

OBJECTIVES

Aim of this Germany-wide study was to evaluate the use and application customs of neuromuscular blocking drugs (NMBDs) for tracheal intubation in children of age 5 years or younger.

MATERIAL AND METHODS

In the year 2005, a total of 3260 questionnaires were sent out to all heads of anesthesia departments at all types of hospitals as well as ambulatory anesthesia centers in Germany. The fields covered by the questionnaire were regarding institutional size, amount of general anesthesia and specifically pediatric cases, number of intubations and NMBDs used, frequency of use of the individual relaxants and techniques utilized when administering muscle relaxants.

RESULTS

Of the sent-out questionnaires 66.9% could be analyzed: 82% of hospitals use 1-3 muscle relaxants in children; 91% of the ambulatory anesthesia centers use a repertoire of 1-2 neuromuscular blockers for pediatric cases. However, general anesthesia with tracheal intubation in children is often induced without using any NMBD at all. Mivacurium is the predominantly used NMBD for pediatric intubation in Germany. In contrast, the use of succinylcholine is far less in ambulatory anesthesia centers than in hospitals. Despite controversial discussion, precurarization, priming, and timing are still utilized in German anesthesia practice.

CONCLUSION

In Germany, mivacurium, with its favorable pharmacologic profile for short cases, is the predominantly used NMBD for pediatric tracheal intubation. Despite the known adverse effects of intubation without muscle relaxation, this technique is also wide-spread, especially among German anesthetists in ambulatory anesthesia centers. Surveys like these are important to determine a status quo of use and application customs of NMBDs in pediatric anesthesia and provide a basis for numerous other studies.

Relative Reliability of the Auditory Evoked Potential and Bispectral Index for Monitoring Sedation Level in Surgical Intensive Care Patients

Sedation is an important adjunct therapy for patients in the intensive care unit. The objective of the present study was to observe correlation between an established subjective measure, the Ramsay Sedation Scale, and two objective tools for monitoring critically ill patients: the Bispectral Index (BIS) and auditory evoked potential. Ninety patients undergoing major surgery scheduled for postoperative mechanical ventilation and continuous sedation with propofol and fentanyl were selected. Electrodes for determining BIS and auditory evoked potential were placed on the foreheads of all patients according to manufacturer's specifications at least six hours after patients’ arrival at the intensive care unit. Ramsay Sedation Scale, BIS, signal quality index, composite A-line autoregressive index (AAI) and electromyographic activities were recorded every five minutes for 30 minutes. BIS and AAI showed good correlation amongst readings (rs=0.697, P <0.07). Both were significantly influenced by electromyographic activities (BIS, rs=0.735, P <0.07; AAI, rs=0.856, P <0.07). Comparison of BIS and AAI revealed an acceptable correlation between electroencephalogram variables and the Ramsay Sedation Scale (BIS, τ=-0.689; AAI, τ=-0.621; P <0.07). In conclusion, the auditory evoked potential and BIS monitors revealed an acceptable correlation with the Ramsay Sedation Scale. However, the BIS and auditory evoked potential monitors do not perform adequately as a substitute in the assessment of sedated intensive care unit patients. These monitors could be used as part of an integrated approach for the evaluation of those patients especially when the subjective scales do not work well in the setting of neuromuscular blockade or may not be sufficiently sensitive to evaluate very deep sedation.

Propofol in paediatric anaesthesia

PURPOSE OF REVIEW

In this review we intend to ascertain trends in propofol administration for paediatric anaesthesia and sedation.

RECENT FINDINGS

Propofol is being 'discovered' by non-anaesthesiologist practitioners of paediatric sedation. However it appears that the drug is not infrequently administered alone for painful procedures, necessitating large doses that result in uncontrolled general anaesthesia with a high potential for adverse events. An elegant technique comprises small doses of short-acting opioid (e.g. fentanyl 1 mug/kg) with low-dose propofol infusion. This does not result in worsening of pre-existing right-to-left intracardiac shunts. The dilemma is to educate non-anaesthesiologists about propofol pharmacokinetics and pharmacodynamics and in particular about the advantages of combined drug therapy. A paediatric target-controlled system for propofol has undergone preliminary clinical evaluation and it is hoped that administration according to pharmacokinetic principles will refine administration to infants and children. Sporadic cases of the propofol infusion syndrome in patients receiving prolonged sedation in intensive care units continue to be reported (characterized by metabolic acidosis, rhabdomyolysis and myocardial failure). It appears that one mechanism may be a deficiency of mitochondrial oxidative processes possibly induced by a dialyzable substance, perhaps a propofol metabolite. Propofol has been used with some success in treating postoperative laryngospasm and for tracheal intubation without muscle relaxants.

SUMMARY

Propofol should be used with extreme caution for prolonged sedation in intensive care unit patients, at dose rates of below 5 mg/kg per h, while maintaining extreme vigilance for signs of developing propofol infusion syndrome. If used correctly propofol is a suitable drug for sedation outside the operating room.

The optimal dose of remifentanil for intubation during sevoflurane induction without neuromuscular blockade in children

The optimal dose of remifentanil needed to produce successful intubating conditions following inhalation induction of anaesthesia using 5% sevoflurane without the use of neuromuscular blocking drugs, was investigated in 25 children aged 3-10 years. Sixty seconds after inhalation induction of anaesthesia using sevoflurane 5% in 100% oxygen, a predetermined dose of remifentanil was injected over 30 s. The dose of remifentanil was determined using the modified Dixon's up-and-down method (0.2 microg x kg(-1) as a step size). The first patient was tested at 1.0 microg x kg(-1) remifentanil. Ninety seconds following the bolus administration of remifentanil, the child's trachea was intubated. The optimal bolus dose of remifentanil required for successful tracheal intubation was 0.56 (0.15) microg x kg(-1) in 50% of children during inhalation induction using 5% sevoflurane in the absence of neuromuscular blocking drugs. Using probit analysis, the 95% effective dose (ED(95)) of remifentanil was 0.75 microg x kg(-1) (95% confidence limits 0.63-1.38 microg x kg(-1)).

[Propofol for paediatric patients in ear, nose and throat surgery. Practicability, quality and cost-effectiveness of different anaesthesia procedures for adenoidectomy in infants]

BACKGROUND

The aim of this study was an improvement in patient comfort, reduction of anaesthesia costs and room contamination by the use of propofol for adenoidectomy.

METHODS

A total of 103 infants (aged 1-5 years) undergoing elective adenoidectomy were randomized for anaesthesia with sevoflurane-nitrous oxide/oxygen (group 1), sevoflurane-air/alfentanil (group 2), alfentanil-propofol under induction with sevoflurane (group 3) or alfentanil-propofol (group 4).

RESULTS

Using propofol, postoperative agitation and emesis were significantly less and the anaesthesia costs as well as the need for analgesics was reduced compared to inhalative anaesthesia.

CONCLUSIONS

The use of propofol for preschool children undergoing ear, nose and throat (ENT) surgery seems to be advantageous because of less postoperative agitation, emesis and costs.

Comparative evaluation of different doses of propofol preceded by fentanyl on intubating conditions and pressor response during tracheal intubation without muscle relaxants

BACKGROUND

The aim of our study was to determine the optimal dose of propofol preceded by fentanyl for successful tracheal intubation and to see its effectiveness in blunting pressor response in children aged 3-10 years.

METHODS

This prospective, double blind, randomized study was conducted on 60 ASA grade I and II children, between 3 and 10 years undergoing elective surgery who were divided into three groups of 20 each. The children received different doses of propofol (group I, 2.5 mg x kg(-1); group II, 3.0 mg x kg(-1); group III, 3.5 mg x kg(-1)) preceded by a fixed dose of fentanyl (3.0 microg x kg(-1)) 3 min earlier. The tracheal intubating conditions were graded based on scoring system devised by Helbo-Hensen et al. with Steyn modification which includes five criteria; ease of laryngoscopy, degree of coughing, position of vocal cords, jaw relaxation, and limb movement and graded on a 4-point scale. Heart rate (HR), mean arterial pressure (MAP), and oxygen saturation changes were also noted.

RESULTS

Tracheal intubating conditions were acceptable in 25% of the patients in group I, while significantly higher (P < 0.001) in group II (80%) and in group III (90%). The pressor response was not effectively blunted in group I (17% increase in HR), while effectively blunted in groups II and III. A fall in cardiac output was seen in group III indicated by a decrease in MAP (16%) and HR (11%). No airway complications were noted.

CONCLUSIONS

Propofol 3 mg x kg(-1) (group II) preceded by fentanyl 3 microg x kg(-1) is the optimal dose combination in our study. It provides acceptable intubating conditions in 80% patients, blunts pressor response to intubation without significant cardiovascular depression.

Airway management in infants and children

Anaesthesiologists, paediatricians, paediatric intensivists and emergency physicians are routinely challenged with airway management in children and infants. There are important differences from adult airway management as a result of specific features of paediatric anatomy and physiology, which are more relevant the younger the child. In addition, a number of inherited and acquired pathological syndromes have significant impact on airway management in this age group. Several new devices--e.g. different types of laryngeal mask airways in various sizes, small fibre-endoscopes--have been introduced into clinical practice with the intention of improving airway management in this age group. Important new studies have gathered evidence about risks and benefits of certain confounding variables for airway problems and specific techniques for solving them. Airway-related morbidity and mortality in children and infants during the perioperative period are still high, and only a thorough risk determination prior to and continuous attention during the procedure can reduce these risks. Appropriate preparation of the available equipment and frequent training in management algorithms for all personnel involved appear to be very important.

The impact of acoustic stimulation on the AEP monitor/2 derived composite auditory evoked potential index under awake and anesthetized conditions

The AEP Monitor/2 features an auditory evoked potential (AEP) and electroencephalogram (EEG)-derived hybrid index of the patient's hypnotic state. The composite AEP index (AAI) is preferably calculated from the AEP, but in case of low signal quality it is based entirely on the spontaneous EEG. We investigated the impact of auditory input on the AAI in 16 patients with correctly positioned headphones for acoustic stimulation and headphones disconnected from the patient's ears under awake and anesthetized conditions. The AAI and the Narcotrend Index (NI), another EEG-based measure of hypnotic depth, were recorded simultaneously. AAI values under awake and anesthetized conditions were higher with correctly positioned headphones than with headphones disconnected from the patient's ears (P < 0.05) but remained within the range indicating the patient's actual hypnotic state as given by the manufacturer of the monitor. Under awake conditions with correctly positioned headphones we observed frequent fluctuations between AEP-derived and EEG-derived AAI, whereas with headphones disconnected from the patient's ears the AAI calculation was completely EEG based. Acoustic stimulation had no impact on the Narcotrend Index. Although relevant misinterpretations of the patient's hypnotic state as a consequence of a turnover from AEP-derived to EEG-derived AAI values should not occur, an improved harmonization of the two methods of indexing would be desirable.

IMPLICATIONS

The AEP Monitor/2 generates an Index (AAITM) indicating the patient's hypnotic state by analyzing either auditory evoked potentials (AEP) or spontaneous electroencephalographic (EEG) activity. We demonstrate that, though significantly different under AEP-derived or EEG-derived conditions, AAI values remain within the range indicating the patient's actual hypnotic state as given by the manufacturer of the device.

Premedication for tracheal intubation: A prospective survey in 75 neonatal and pediatric intensive care units*

OBJECTIVE

In children, like in adults, tracheal intubation is a painful procedure that may induce hypertension, tachycardia, and other undesirable hemodynamic disorders. Although premature neonates are very sensitive to pain and vulnerable to its long-term effects, the need for sedation before tracheal intubation is still discussed in neonatal units. Our objective was to investigate the practice of premedication before tracheal intubation in neonatal and pediatric units and determine the influence of premedication on intubating conditions.

DESIGN

We performed a 10-day prospective survey in 75 neonatal and pediatric intensive care units among the 98 licensed in France. A questionnaire was completed for each intubation performed in each surveyed unit.

SUBJECTS

A total of 204 patients were studied: 140 neonates, 52 infants, and 12 children.

MAIN RESULTS

Data on 204 tracheal intubations were collected from 223 that were performed during the study period (participation rate, 91.4%). Premedication was used before intubation for 37.1%, 67.3%, and 91.7% of neonates, infants, and children, respectively (p <.0001). In the subgroup of neonates, premedication was particularly rare for the youngest and the smallest infants. Midazolam was the principle hypnotic used in neonates, whereas propofol was mainly used in children. Opioids or muscle relaxants were used in 16.2% and 4.4% of the patients, respectively. A low success rate and a high incidence of hypoxemia and bradycardia were correlated with the inexperience of the operator. Premedication did not significantly influence either the success rate or the undesirable events associated with tracheal intubation.

CONCLUSION

Use of premedication before tracheal intubation is limited in neonates and increases according to the age of the patient. Midazolam does not seem to be an accurate choice to improve intubating conditions in neonates and infants. Because tracheal intubation is a technique that requires a skill only developed by regular practice, operators who have limited experience with intubating children should be supported by senior operators.

Endotracheal Tube Cuff Pressure Is Unpredictable in Children

The use of cuffed tracheal tubes in children younger than 8 yr of age has recently increased, although cuff hyperinflation may cause tracheal mucosal damage. In this study, we sought to measure the cuff pressure (P(cuff)) after initial free air inflation (iP(cuff)) and to follow its evolution throughout the duration of 50% nitrous oxide (N(2)O) anesthesia. One-hundred-seventy-four children, aged 0 to 9 yr, fulfilling the following criteria, were studied: 1). weight of 3-35 kg; 2). ASA physical status I or II; 3). elective surgery; 4). anesthesia with tracheal intubation using a cuffed tube and lasting at least 45 min; and 5). gas mixture containing 50% N(2)O. Free air inflation results in variable iP(cuff), with hyperinflation in 39% of cases. Numerous gas removals were required to maintain P(cuff) less than 25 cm H(2)O in 85% of the patients. The number of deflations decreased with the duration of mechanical ventilation and was small after 105 min. No difference was observed among the different cuffed tube sizes. We conclude that iP(cuff) is unpredictable after free air inflation and that numerous gas removals are required to maintain P(cuff) less than 25 cm H(2)O during N(2)O anesthesia in children.

IMPLICATIONS

Free inflation of the tracheal tube cuff, controlled only by the palpation of the pilot balloon, is not reliable and results in extremely variable (and sometimes very high) initial cuff pressures in children. In addition, nitrous oxide anesthesia may result in cuff hyperinflation requiring numerous gas removals.

The use of remifentanil for intubation in paediatric patients during sevoflurane anaesthesia guided by Bispectral Index (BIS) monitoring

We studied the intubating conditions, haemodynamic and endocrine changes following tracheal intubation during sevoflurane anaesthesia guided by Bispectral Index (BIS) monitoring in 40 children who received either remifentanil 1 microg.kg-1 (group R) or saline 1 ml.kg-1 (group S). Acceptable intubating conditions were found in all patients in group R (n = 20), compared to only 12 patients in group S (p = 0.002). There were no intergroup differences in heart rate, systolic blood pressure and plasma concentrations of epinephrine and norepinephrine at any time point and changes in haemodynamic variables throughout the study period were moderate. Titration of sevoflurane delivery to a target BIS of 35 +/- 5 led to almost equal end-tidal sevoflurane concentrations in either group and remifentanil did not affect the BIS. There were no side-effects in either group that required intervention. Intubating conditions during sevoflurane anaesthesia in children were found to be improved by a single bolus dose of remifentanil 1 microg.kg-1.

Management of the paediatric airway: new developments

During the last 2 years, some interesting new devices have been made available to improve airway management in children and infants, and several studies have advanced our understanding concerning risks and benefits of the current practice in the field. Certain risk factors for airway related problems during anaesthesia in children having a cold have been identified, and new aspects of the controversy concerning the use of cuffed endotracheal tubes in children presented. Novel video-assisted systems have been introduced for the management of the difficult airway in paediatric patients, and new applications for well known devices have been suggested, such as the laryngeal mask airway serving as guidance for fibreoptic intubation. Recent studies also demonstrated specific problems with the laryngeal mask airway in infants, as well as the advantages of a new prototypic laryngeal mask airway for children, similar to the ProSeal (LMA International S.A. Group, USA). Furthermore, the following review presents new data about the use of the cuffed oropharyngeal airway, the laryngeal tube, and the Arndt bronchus blocker in paediatric patients.